Volume 17 March 2005 ISSN: 1528-0470 GULF AND CARIBBEAN RESEARCH Published by The University of Southern Mississippi GULF COAST RESEARCH LABORATORY Ocean Springs, Mississippi Gulf and Caribbean Research Volume 17 Issue 1 January 2005 Argulus yucatanus N. Sp. (Crustacea: Branchiura) Parasitic on Cichlasoma urophthalmus from Yucatan^ Mexico William J. Poly Calif ornia Academy of Sciences DOI: 10.18785/gcr.l701.01 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Poly; W. J. 200 S. Argulus yucatanus N. Sp. (Crustacea; Branchiura) Parasitic on Cichlasoma urophthalmus from Yucatan^ Mexico. Gulf and Caribbean Research 17 (l): 1-13. Retrieved from http://aquila.usm.edu/gcr/voll7/issl/ 1 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf and Caribbean Research Vol 17, 1-13, 2005 Manuscript received July 1, 2004; accepted November 15, 2004 ARGULUS YUCATANUS N. SP. (CRUSTACEA: BRANCHIURA) PARASITIC ON CICHLASOMA UROPHTHALMUS FROM YUCATAN, MEXICO William J. Poly California Academy of Sciences, 875 Howard Street, San Francisco, California 94103 USA, E-mail wpoly@calacademy.org ABSTRACT A new species, Argulus yucatanus, is described based on 14 specimens from Cichlasoma urophthalmus collected in Celestun Lagoon, Yucatan, Mexico. Diagnostic characters include the number of and shape of sclerites in the suction cup support rods, shape of and position of respiratory areas, and modifications on the legs of males. In males, the coxae of the 2nd legs bear an angular lobe with 5-7 erect scales and 13-21 sensilla. The new species is compared to Argulus funduli Krpyer, 1863, A. chromidis Krpyer, 1863, A. cubensis Wilson, 1936, A. rhamdiae Wilson, 1936, and A. various Bere, 1936. RESUMEN Una. nueva especie, Argulus yucatanus, esta escrito de catorce especimenes de Cichlasoma urophthal- mus colectaron del Estero de Celestun, Yucatan, Mexico. Varios caracteres la distinguen con inclusidn del numerd de y de la forma de escleritos en las rayas de las ventosas, de las areas respiratorias y de las modificacidnes en las patas de los machos. En los machos, las segundas parejas de las patas tienen un lobulo angular con 5-7 escamas erguidas y 13-21 sensillas. Argw/Mv/wnr/w/i Krpyer, 1863, A. chromidis Krpyer, 1863, A. cubensis WAson, 1936, A. rhamdiae Wilson, 1936 y A. various Bere, 1936 estan comparado a la nueva especie. Introduction Only 3 species of Argulus have been described from Mexico (Wilson 1936a, Pineda et al. 1995, Poly 2003), namely A. rhamdiae Wilson, 1936, A. mexicanus Pineda, Paramo and Del Rio, 1995, and A. amby stoma Poly, 2003. In addition, 4 other species of Argulus have been listed as components of the Mexican fauna (see Poly 2003). The present study includes a description of one new species from Mexican waters and comparisons of the new species with other species that are either similar to it in some fea- tures or that occur in the region. Also, new data and illus- trations are included for 2 poorly known species, A. chro- midis Kr0yer, 1863 and A. cubensis Wilson, 1936. Materials and Methods All specimens were fixed and stored in 4% formalin in 1994 and were transferred to 70% ethanol in 1998. Six females and 8 males (13 mature, 1 immature male) were examined under dissecting and compound microscopes in a watchglass or as a temporary slide mount (with 70% ethanol and Hoyer’s medium). Drawings were made with the aid of a camera lucida. All measurements were made using an ocular micrometer, and measurements reported below are arranged as follows: range (mean, holotype) with allotype values substituted for females. Width of first antennae refers to the distance from the mesial margin of the basal segment to the farthest extent of bend in the ter- minal spine on the 2nd segment. Two males and one female also were examined using scanning electron microscopy, and preparation procedures were modified slightly from those of Rupp (1990). Specimens were dehy- drated in an ethanol series consisting of 80% (5 min), 90% (5 min), 100% (1st, 5 min; 2nd, 10 min), then critical point dried, mounted on metal stubs with carbon paint, allowed to dry in an oven (60 °C), and sputter coated with gold/pal- ladium. Type specimens were deposited in the American Museum of Natural History, New York (AMNH), in the Museum of Comparative Zoology, Cambridge, Massachusetts (MCZ), and in the author’s collection. The syntypes of A. funduli (ZMUC CRU-6473, 4 males, 2 females [data collected from 2 males and 2 females]), the holotype of A. chromidis (ZMUC CRU-6030, 1 female, poor condition) (both from the Zoologisk Museum, Copenhagen, Denmark), and the syntypes, along with other specimens, of A. cubensis (MCZ 8973 [syntypes], 1 male, 1 female; MCZ 9643 [non-types], 2 females) were examined for comparison with the new species using the methods described above. Information about A. varians was obtained from literature sources (Bere 1936, Bouchet 1985). Results Family Argulidae Rafinesque, 1815 Argulus Muller, 1785 Argulus yucatanus, n. sp. Yucatan fishlouse Figures 1-7, Tables 1-2 Material examined. Holotype — adult male, 2.83 mm total length, AMNH Crustacea 18469, Estero de Celestun (Celestun Lagoon), Yucatan, Mexico, 4 November 1994, 1 Poly collector: FrantiTiek Moravec. Allotype: adult female, 3.33 mm total length, AMNH Crustacea 18470. Other paratypes: 1 adult male, 1 adult female, AMNH Crustacea 18471; 2 adult males, 1 immature male, 2 adult females, MCZ 50725; 3 adult males, 2 adult females (includes SEM specimens), author’s collection; all paratypes collected with holotype. Diagnosis. Two respiratory areas with smaller, circu- lar to ovoid “area” anterior to larger posterior “area;” postantennal spines single; males with 37-46 support rods per suction cup; females with 43-51 support rods per suc- tion cup; usually 2-3 sclerites per rod in males, 3-5 scle- rites per rod in females; mouth tube with 2-5 (usually 4) scales on basal half; bushy fringe of fine setae on margin of labium; basal plate of 2nd maxilla with 3 stout, digitate spines, larger scales on anterior of pad with smaller scales posteriorly, scales round to ovoid with coarse-pectinate margin, 3-8 stout, naked setae on posterior margin of pad; first 2 pairs of legs lacking flagella; posteroventral surface of coxae of 2nd legs of males with an angular, fleshy lobe bearing 5-7 erect scales on posterior margin and 13-21 sensilla; 3rd legs of males with 2 ornamented pegs issuing from cleft on dorsal side of legs; male abdomen much longer and narrower than female abdomen; spermathecae of female ovate, relatively large; testes of male extend entire length of abdomen; caudal rami long, slender, basal in anal sinus. Description. Total length (mm) 2.17-3.38 (2.88, 2.83) in males, 2.80-3.88 (3.40, 3.33) in females. Carapace shape as shown in Figures lA, B, with cephalic region distinctly separated from alae. Carapace length (mean of both alae, mm) 1.30-2.00 (1.73, 1.69) in males, 1.95-2.67 (2.42, 2.39) in females. Maximum carapace width (mm) 1.18-2.00 (1.68, 1.65) in males, 1.75-2.55 (2.21, 2.12) in females. Carapace extending as far as ante- rior margin of to middle of 3rd legs in males, as far as ante- rior margin of 3rd legs to anterior margin of 4th legs in females. Females with eggs in thorax but not in carapace alae. Sensilla and pores scattered on dorsal surface and margins of carapace; fringe of small sensilla with larger sensilla interspersed along cephalic margin of carapace. Pair of compound eyes anteriorly with diameters (left and right eyes, pm) 100-150 (122, left: 110, right: 110) in males, 120-150 (130, left: 130, right: 130) in females. Transverse distance between eyes (pm) 340-510 (421, 420) in males, 480-630 (558, 520) in females. Nauplius eye with one anterior and 2 posterior ocelli. Sclerotized dorsal ridges not forked anterior of eyes. Ventrally, cara- pace with small, posteriorly-projecting spines along outer margin, more numerous anterior of respiratory areas with few spines occurring beyond anterior margin of larger res- piratory area. Respiratory areas consist of smaller, circular to ovoid “area” anterior to larger, posterior ovoid “area” (Figures IC-E); respiratory areas not outlined with pig- ment (possibly lost in preservative). Color in preservative white to light yellow; no other pigmentation present (pos- sibly lost in preservative). Thorax compressed dorsoventrally, 4-segmented, with 2 pairs of posteriorly-projecting spines ventrally. Spines digitate, anterior pair (accessory spines) usually larger than posterior pair (postmaxillary spines). Accessory spines between basal segments of 2nd maxillae. Postmaxillary spines farther apart than accessory spines. Males with ovoid fleshy lobe at posterior of 4th thoracic segment between natatory lobes (Figures 2 A, B). Thorax with coarse-pectinate scales scattered on ventral surface (Figure 2A). Dorsal surface of thorax with sensilla; typically one sensillum at midline of posteror margins of 2nd and 3rd thoracic segments with others variously placed (Figure 2C). Four pairs of biramous swimming legs composed of a precoxa, coxa, basis, exopod, and endopod (Figure 2A). Exopods and endopods with plumose setae. Setae usually absent from coxae of 2nd and 3rd legs; see Table 1 for number of setae on legs. Eirst 2 pairs of legs lacking fla- gella. Endopods of first pair of legs 3 -segmented with 3 setae distally. Endopods of 2nd pair of legs unsegmented. Endopods of 3rd and 4th pairs of legs 2-segmented. Second, 3rd, and 4th legs of males with secondary sexual structures (Eigure 2A). Coxae of male 2nd legs with an angular, fleshy lobe posteroventrally with 5-7 (6, 7) erect scales on posterior margin and 13-21 (17, 19-21) sensilla (Eigure 2D); number of erect scales on angular lobe excludes prostrate coarse-pectinate scales present on ven- tral surface of coxae. Dorsal surface of coxae of male 3rd legs covered with closely-arranged fine-pectinate scales (Eigures lA, 2E). Two ornamented pegs issue dorsally from joint between coxa and basis of male 3rd legs with fine-pectinate feather-like scales posterior and ventral to the pegs (Eigures 2E, E, 3A, B). Pegs with horn dorsally; orifice of pegs containing many bi-pronged and multi- pronged projections from inner wall. Dorsal surface of pre- coxae of male 3rd legs with many small sensilla. Bases of male 4th legs with 2 opposing blunt lobes on anterior sur- face; dorsal lobe with scaled area anteriorly (non-pectinate scales) and small patch of tubercles distally (Eigures 3C, D). Precoxae and coxae of male and female 4th legs with posterior natatory lobes fringed with plumose setae and bearing scales and sensilla. Eemale natatory lobes with more scales and sensilla than those of male. Bases of 4th legs of both sexes larger than bases of other legs. Coarse- pectinate scales on ventral surfaces of precoxae and coxae (Eigure 3E). 2 New Species oe Argulus Figure 1. Argulus yucatanus, n. sp. A) Male, dorsal view (holotype, 2.83 mm total length, AMNH Crustacea 18469). B) Female, dorsal view (allotype, 3.33 mm total length, AMNH Crustacea 18470). C-E) Shape of respiratory areas and distribution of adja- cent spines on: C) holotype (male), D) allotype (female), E) paratype (female, AMNH Crustacea 18471). For clarity, plumose setae were not shown on endopods and exopods of legs (lA, B). Number of setae illustrated on bases is actual number present on these particular specimens (lA, B); dorsal and ventral rows of setae can be seen on the bases of 3rd legs (IB). Eggs in tho- rax shown by dashed lines (IB). Scale: C-E = 200 pm. 3 Poly Figure 2. Argulus yucatanus, n. sp. (males). A) Ventral view of legs, thorax, and abdomen; legs numbered 1-4 on coxae, ss = sim- ple seta, ps = plumose seta, fl = fleshy lobe. B) Distribution of scales on ventral surface of abdomen (ab) and fleshy lobe (fl) between natatory lobes. C) Sensillum at midline of thorax at posterior margin of 3rd thoracic segment (th3), extending over 4th thoracic segment (th4). D) Angular, fleshy lobe on coxa of 2nd leg (ventral view); pc = precoxa, c = coxa, b = basis, ss = simple seta. E) Pair of pegs and fine-pectinate scales covering portions of coxa of 3rd leg (dorsal view). F) Close-up of pegs on 3rd leg (dorsal view). Scale: A, B, D, E = 100 pm; C, F = 10 pm. 4 New Species oe Argulus TABLE 1 Number of setae on coxae and bases of legs of Argulus yucatanus, n. sp. Separate counts of both right and left legs for each individual were included (8 males, 6 females; range followed by mean in parentheses). Most setae were plumose; some setae have small plumes and sometimes appeared simple. There is usually a single, simple seta or sensillum not associated with the others on the coxae and bases of legs 1-3, and these were not included in the counts. Coxa (Ventral) Basis (Ventral) Basis (Dorsal) Leg 1 Male 1-2 (1) 2-4 (3) 0 Female 1(1) 2-3 (3) 0 Leg 2 Male 0-1 (0)^ 1-3 (3) 1-4 (3) Female 0 2-4 (3) 3-5 (4) Leg 3 Male 0 1-2 (2) 0 Female 0 2-4 (3) 3-4 (4) Leg 4 Male 6-10 (8) 4-6 (5) 0 Female 13-23 (20) 6-10 (8) 0 ^Only one of 16 legs from 8 specimens with a seta; setae usually not present on segment Abdomen bilobate. Each lobe with single row of small, coarse-pectinate scales along posterolateral edges and small sensilla near tips and along lateral margins in both sexes. Male abdomen longer and narrower than female abdomen (Figures lA, B). Abdomen length (mm) 0.76-1.09 (0.99, 1.00) in males, 0.68-0.93 (0.83, 0.82) in females; maximum width (mm) 0.45-0.55 (0.50, 0.49) in males, 0.46-0.71 (0.64, 0.65) in females. Anal sinus length (pm) 200-320 (282, 290) in males, 290-340 (318, 320) in females. Caudal rami paired, long, slender, at base of anal sinus; each ramus with 5 stout, naked “setae” (Figure 3F). Spermathecae of female paired, brownish, ovate, relatively large, located anteriorly on abdomen (Figure IB). Abdominal papillae absent on female abdomen. Testes of male occupy much of abdomen, extending entire length of abdominal lobes (Figure lA). Abdomen of male with coarse-pectinate scales on ventral surface anterior of anal sinus (Figure 2B). First antennae 4-segmented. First segment (basal seg- ment) sclerotized, large with stout posteriorly-projecting posterior spine; 2nd segment sclerotized with small recurved spine anteriorly, posteriorly-projecting medial spine, and large recurved terminal spine; 3rd segment fleshy, cylindrical with large, stout seta distally that proj- ects ventrally and several smaller setae; 4th segment fleshy, small, with few setae distally (Figures 4A, B). Width of first antennae (mean of both antennae, pm) 210-280 (256, 255) in males, 280-360 (330, 325) in females. Second antennae 5-segmented, fleshy. First 2 segments larger; remaining 3 thin, cylindrical; basal segment bears posteri- orly-projecting posterior spine. All segments of 2nd anten- nae with several long, stout setae that project distally; some reaching to or beyond junction with next segment. Postantennal spines single (as opposed to double in some taxa), large, rounded or pointed distally (Figures 4A, B). First maxillae modified into suction cups in adults. In males, first maxillae inner diameter (pm) 220-290 (241, left: 230, right: 220) (n = 14, left and right) and outer diameter (pm) 310-420 (352, left: 350, right: 340) {n = 14). In females, inner diameter (pm) 370-450 (428, left: 410, right: 410) (n= 12, left and right) and outer diameter (pm) 500-650 (595, left: 570, right: 570) {n = 12). See Table 2 for number of support rods in suction cups. Number of sclerites per support rod in males 1-4 (2, 2, range 1-3) (n = 596 support rods) and in females 1-5 (4, 4, range 1-5) (n = 549 support rods). Usually 2-3 sclerites per rod in males, 3-5 sclerites per rod in females; lower counts such as one due to missing sclerite(s) or atypical development, uncommon. Number of sclerites variable with position on suction cup; shape of sclerites variable; orientation of rods changes at 2 points on rim of suction cup (Figure 5, see Discussion). Basal (proximal) sclerite usually rod-shaped, longer than other sclerites. Distal scle- rites bowl- or cylinder-shaped. Suction cups with 9-15 (12, 12) sensilla on inside circumference; sensilla with pore at tip and with or without tentacles distally (Figures 6A-C). Short, conical sensilla, with pore distally, on rim of suction cup between basal sclerites of some support rods (Figures 6 A, D). Second maxillae 5-segmented with broad basal plate bearing 3 stout, digitate spines, usually larger space between lateral spine and central spine (Figures 6E, F). Basal plate with elevated pad bearing 3-4 large (anteriorly) and more smaller coarse-pectinate scales and 3-8 stout setae that 5 Poly Figure 3. Argulus yucatanus, n. sp. (males). A) Peg on 3rd leg (dorsal view), rotated partially toward anterior face. B) Anterior face of a peg illustrating detail of ornamentation; note feather-like scales below the peg. C) Ventral view of basis of 4th leg with 2 opposing lobes, one of which has a scaled area anteriorly (non-pectinate scales) and patch of small tubercles distally. D) Dorsal view of basis of 4th leg. E) Coarse-pectinate scale on base of mouth tube; this is the typical coarse-pectinate scale found on ven- tral side of thorax, mouth tube, coxae, and basal plate of 2nd maxillae of both sexes and ventral side of abdomen of males. F) Caudal rami at base of anal sinus of abdomen (dorsal view, male). Scale: A, B, E, F = 10 pm; C = 50 pm; D = 100 pm. 6 New Species oe Argulus Figure 4. Argulus yucatanus, n. sp. A, B) First and 2nd antennae and postantennal spine (ventral view; A, male; B, female). Scale: A, B = 100 pm. extend posteriorly, usually over space between central and lateral posterior spines (Figures 6E, F). Scales and setae/sensilla on ventral surfaces of last 4 segments. Distal segment with 2 sharp claws and 1 blunt, elongate lobe posi- tioned above claws, with small sensillum at tip of lobe. Mouth tube of moderate length, usually not reaching thoracic accessory spines, with 2-5 (usually 4) scales on basal half (Figures 3E, 7A). Labium with fringe of fine setae around mouth (Figures 7 A, B); labrum with embed- ded scales around mouth (Figure 1C). Two pairs of sensil- la on both labium and labrum; 3 other pairs of similar structures on mouth tube (Figure 7B). Pair of serrated mandibles and pair of labial ducts inside mouth tube (Figure 1C). Preoral stylet present, when extended usually reaching as far as area anterior of first antennae nearly to anterior margin of carapace (Figure 4C). Short projections and orifice near tip of stylet (Figure 7D). Host. Cichlasoma urophthalmus (Gunther), Mayan cichlid. Etymology. The specific name, yucatanus, is derived from the state in which the type locality is located (Yucatan, Mexico) and is treated herein as a noun in apposition. Remarks. Male A. yucatanus and A. funduli Krpyer, 1 863 are quite similar in the shapes of the cephalic region, carapace, and abdomen as seen from a dorsal view; how- ever, A. yucatanus can be distinguished from A. funduli by the much lower number of sclerites in the suction cup sup- port rods (2-5 vs. 1 1-26, respectively {n = 4, A. funduli, mean =17; 290 rods)), and A. yucatanus also has fewer support rods per suction cup than A. funduli (37-51 vs. 53-64, respectively {n = 4, A. funduli, mean = 58; 8 suc- tion cups)). Argulus yucatanus has a pair of accessory spines and a pair of postmaxillary spines, whereas A. fun- duli lacks both pairs of spines. Argulus funduli has more TABLE 2 Number of support rods in first maxillae (suction cups) of male and female Argulus yucatanus, n. sp. (numbers for holotype and allotype in bold). ®Not counted Male {n - 8) Eemale {n - 6) Left Suction Cup 37 42 41 44 45 42 46 40 51 46 43 49 48 44 Right Suction Cup 42 44 43 43 43 43 42 — ^ 48 48 46 47 47 46 X = 43; Range = 37-46 x = 47; Range = 43-51 X = 44; Range = 37-51 (male and female) 7 Poly Figure. 5. Argulus yucatanus, n. sp. Suction cup (first maxilla) rim, support rods, and fringe of setae (allotype, AMNH Crustacea 18470, left side); arrows indicate points at which orientation of rods changes; A = anterior, P = posterior, L = lateral, M = medi- al. Note missing sclerites in one rod. Scale: 200 pm. scales on the mouth tube than A. yucatanus. Male A. fun- duli do not have the secondary sexual modification on the coxae of the 2nd legs as do male A. yucatanus. The shape and position of the respiratory areas are similar, but not identical, between the 2 species, and both differ in features of the basal plate of the 2nd maxilla. Argulus varians Bere, 1936 resembles A. yucatanus in shapes of the cephalic region and carapace, absence of fla- gella on legs, and number and shape of sclerites in suction cup rods, but they can be distinguished from each other by the size of and shape of the respiratory areas and differ- ences in the shape of the abdomen. The natatory lobes of female A. varians possess a projection posterolaterally that is not present on the natatory lobes of female A. yucatanus, and the spermathecae of A. varians differ from those of A. yucatanus, following information given in Bere (1936) and Bouchet (1985). Male A. varians differ from male A. yucatanus in the secondary sexual modifications on the legs. Argulus chromidis and A. cubensis both have flagella on the first 2 pairs of legs, round spermathecae, and eggs in the carapace alae of gravid females (in addition to those in the thorax); however, Krpyer (1863) exaggerated the egg distribution in the carapace of A. chromidis in his drawing (the hexagonal pattern on the specimen). In addi- tion, the number of setae on leg segments, shape of respi- ratory areas, shape of body, and features of the 2nd maxil- lae of both species differ markedly from A. yucatanus (Figures 8B, C, E, F). Secondary sexual modifications on the legs of male A. cubensis differ from those of male A. yucatanus. Argulus cubensis has 39-49 support rods {n = 4, A. cubensis, mean = 45; 7 suction cups) and 4-6 scle- rites per rod (mean 4, 217 rods; Figure 8D). Argulus chro- midis lacks armature on the mouth tube, and the single suc- tion cup available for A. chromidis had 42 support rods and 3-5 sclerites per rod (mean = 4; 41 rods; Figure 8A). The brief description of Argulus rhamdiae (based on a single female) does not agree with A. yucatanus in body shape. New Species oe Argulus Figure. 6. Argulus yucatanus, n. sp. A) Conical sensillum (cs) and sensillum (s) on rim (r) and inner margin (im), respectively, of suction cup (male); note pore at tip of sensillum on inner margin of suction cup. B) Sensillum (s) on inner margin of suction cup; r = rim of suction cup (female). C) Sensillum with tentacles distally on inner margin of suction cup (male). D) Close-up of conical sensillum near basal sclerite on rim of suction cup (male); note pore at tip. E) Second maxilla, accessory spine, and post- maxillary spine (male, right side). F) Basal plate of 2nd maxilla and adjacent stalked protozoan parasites at upper right (female, right side). Scale: A, B = 5 pm; C, D = 1 pm; E, F = 100 pm. 9 Poly Figure. 7. Argulus yucatanus, n. sp. A) Mouth tube with 4 scales on basal portion (male). B) Mouth tube; note dense fringe of fine setae along margin of labium and sensilla on mouth tube, labium, and labrum (male). C) Labial ducts (Id) and mandibles (m) inside mouth (female); note openings at tips of labial ducts. D) Tip of preoral stylet with protuberances and opening (male). Scale: A = 50 pm; B, C = 10 pm; D = 1 pm. 10 New Species oe Argulus Figure 8. Argulus chromidis (holotype, female, ZMUC CRU-6030). A) Support rods from anterolateral portion of suction cup (fringe of setae not shown). B) Respiratory areas. C) Basal plate of left 2nd maxilla. Argulus cubensis (syntype, male, MCZ 8973). D) Support rods and fringe of setae from anterolateral portion of suction cup. E) Respiratory areas; note that scalloped appearance is an artifact of preservation and distortion. F) Basal plate of right 2nd maxilla. Scale: A, C, D, F = 100 pm; B, E = 500 pm. characters of 2nd maxillae, shape of sclerites in suction cup support rods, or size and shape of spermathecae according to information given in the original description (see Wilson, 1936a); however, the type specimen of A. rhamdiae could not be located for direct comparison. Discussion Variation in number of and shape of sclerites was observed on A. yucatanus as was noted for several other species (Fryer 1959, Avenant-Oldewage and Oldewage 1995, Poly 2003; Figure 5). In A. yucatanus higher num- bers of sclerites per rod occur in the anterolateral section of a suction cup and the sclerites tend to be more bulbous or round anterolaterally, whereas sclerite numbers are lower posteriorly and on mesial (inner) margin, and scle- rites tend to be more slender. There also is a bilateral divi- sion of the suction cups that can be seen in the orientation of the rods, particularly the basal sclerites, and this has not been pointed out previously for any argulid. The orienta- tion changes at 2 points, anterolaterally and posteromesial- ly, and at one of these points, the thickened, uneven edges of the basal sclerites face one another, whereas at the oppo- site point, the thin edges face (Figure 5). This same type of change in orientation of the rods has been observed in other Argulus spp. (e.g., A. cubensis. Figure 8D), but not all species have this feature (W. Poly pers. obs.). For A. yucatanus the number of rods on each “half’ of a suction cup, as divided by the change in orientation, usually are not equal, with a slightly higher number occurring on the mesial side (means of 24 vs. 20). The bilateral division probably is an expression of normal bilateral symmetry of the body present in many metazoan phyla, although being slightly asymmetrical in this case. Cunnington (1931:262) illustrated 4 suction cup support rods of Argulus carteri Cunnington, 1931, showing the change in orientation at one point on a suction cup (his Plate 15, Figure 14), stat- ing only that “... the apparently meaningless variations of these chitin rays afford additional evidence which it would be unwise to ignore.” Argulus yucatanus is the eighth Argulus species known to occur in Mexico. None of the other Argulus spp. that parasitize cichlids in the Gulf of Mexico and Caribbean region are similar to A. yucatanus. Argulus chromidis was described from a single female specimen, collected at Lake Nicaragua on the gills of a species of “Chromis'' which Gill (1903) pointed out was likely a species of cichlid, whereas Argulus cubensis was discov- ered in Cuba on the cichlid, Cichlasoma tetracanthus (Krpyer 1863, Wilson 1936b). Structures on the bases of the 4th legs of A. yucatanus and A. kosus Avenant- Oldewage, 1994 appear to be nearly identical, and males of both species also have a fleshy lobe between the coxae of the 4th legs. However, there are numerous differences, e.g.. 11 Poly body shape, features of the first and 2nd maxillae, and sec- ondary sexual structures on legs of males, to name a few, that distinguish these 2 species (Avenant-Oldewage 1994, Van As et al. 1999). The pair of pegs on the 3rd legs of male A. yucatanus resemble structures on males of other species, including A. arcassonensis Cuenot, 1912, A. kusafugu Yamaguti and Yamasu, 1959, and A. kosus (Yamaguti and Yamasu 1959, Masson and Delamare Deboutteville 1962, Van As et al. 1999). The parasites of Cichlasoma urophthalmus have been studied by Salgado-Maldonado and Kennedy (1997), Moravec et al. (1998), and Vidal-Martinez et al. (1998). Argulus yucatanus serves as an intermediate host of the nematode, Mexiconema cichlasomae, whose definitive host is C. urophthalmus (Moravec et al. 1999) and was abundant on C. urophthalmus in Celestun Lagoon in 1994 (Moravec et al. 1998). Argulids were reported as a compo- nent of the diet of C. urophthalmus in Celestun Lagoon (Martinez-Palacios and Ross 1988). Celestun Lagoon is estuarine/marine with variable salinities throughout (Martinez-Palacios and Ross 1992, Herrera- Silveira 1994). The lagoon contains a mixture of estuarine and marine fish species, and C. urophthalmus inhabits freshwater as well as brackish to marine habitats (Salgado-Maldonado and Kennedy 1997). Vidal-Martinez et al. (1998) reported Argulus mexicanus from C. urophthalmus in freshwater; possibly their specimens were not A. mexicanus, but rather, A. yucatanus. There are noteworthy points to make concerning A. funduli. Wilson (1902) and others have indicated incorrect- ly that the description of A. funduli was based on a female specimen, but that the specimen illustrated was a male. In the original description, the figure legends were given in both Danish (p. 97 [p. 23 of separate]) and Latin (p. 412 [p. 338 of separate]) with the former referring to a male and the latter to a female. This author agrees that Krpyer’s fig- ure depicts a male specimen (Krpyer 1863, his Plate 2, Figure la). In addition, the original description includes remarks about the length of the carapace of both the male and the female, and the single lot of specimens registered as types of A. funduli contains 6 specimens (collected in the vicinity of New Orleans, Louisiana, USA), including both sexes, in the same state of preservation and represent- ing one species (ZMUC CRU-6473). Therefore, after read- ing a complete translation of the original description, no doubt exists that the description was based on more than one specimen (both male and female), and all 6 specimens are syntypes. After examining the types of A. funduli and comparing them with other descriptions, published illus- trations, and other specimens, it became quite clear that the name A. funduli has been applied incorrectly to other species. Some illustrations of A. funduli in Wilson (1902), Meehean (1940), Cressey (1972), Kabata (1988), and Overstreet et al. (1992) appear to represent species other than A. funduli. Results of an investigation into the taxon- omy of A. funduli will be reported elsewhere. Acknowledgments Special appreciation is expressed to F. Moravec (Institute of Parasitology, Academy of Sciences of the Czech Republic) for his generosity in providing the speci- mens of A. yucatanus for the description. W.G. Dyer (Southern Illinois University) facilitated some of the spec- imen loans and provided lab space and equipment. S. Schmitt and D. Gates (Southern Illinois University, Integrated Microscopy and Graphics Expertise) helped with specimen preparation, examination, and photography. J. Olesen (Zoologisk Museum), M. Siddall (AMNH), and A. Johnston (MCZ) loaned or cataloged specimens, and T.C. Walter (National Museum of Natural History) searched for the type of A. rhamdiae. M.E. Petersen (Zoologisk Museum) kindly translated Krpyer’s original description of A. funduli, and V. Carrero checked the gram- mar of the Spanish abstract. Three anonymous reviewers provided helpful comments on the manuscript. This proj- ect was funded by a grant from the American Museum of Natural History’s Lerner-Gray Fund for Marine Research and by the author. Literature Cited Avenant-Oldewage, A. 1994. A new species of Argulus from Kosi Bay, South Africa and distribution records of the genus. Koedoe 37:89-95. Avenant-Oldewage, A. and W.H. Oldewage. 1995. A new species of Argulus (Crustacea: Branchiura) from a bony fish in Algoa Bay, South Africa. South African Journal of Zoology 30:197-199. Bere, R. 1936. Parasitic copepods from Gulf of Mexico fish. American Midland Naturalist 17:577-625. Bouchet, G.C. 1985. Redescription of Argulus varians Bere, 1936 (Branchiura, Argulidae) including a description of its early development and first larval stage. Crustaceana 49:30-35. Cressey, R.F. 1972. The genus Argulus (Crustacea: Branchiura) of the United States. Biota of Freshwater Ecosystems, U.S. Environmental Protection Agency Identification Manual 2. U.S. Government Printing Office, Washington, DC, USA, viii + 14 p. Cunnington, W.A. 1931. Reports of an expedition to Brazil and Paraguay in 1926-27, supported by the Trustees of the Percy Sladen Memorial Eund and the Executive Committee of the Carnegie Trust for Scotland. Argulidae. Journal of the Linnean Society of London, Zoology 37(252):259-264, 2 pis. 12 New Species oe Argulus Fryer, G. 1959. A report on the parasitic Copepoda and Branchiura of the fishes of Lake Bangweulu (northern Rhodesia). Proceedings of the Zoological Society of London 132:517-550. Gill, T. 1903. The hosts of argulids and their nomenclature. Science, n. ser. 17:33. Herrera-Silveira, J.A. 1994. Spatial heterogeneity and seasonal patterns in a tropical coastal lagoon. Journal of Coastal Research 10:738-746. Kabata, Z. 1988. Copepoda and Branchiura. In: L. Margolis and Z. Kabata, eds. Guide to the parasites of fishes of Canada, Part II, Crustacea. Canadian Special Publication of Fisheries and Aquatic Sciences 101, Department of Fisheries and Oceans, Ottawa, Ontario, Canada, p. 3-127. Krpyer, H. 1863. Bidrig til kundskab om snyltekrebsene. Naturhistorisk Tidsskrift (raekke 3) 2:75-320, 9 pis. (contin- ued, 321-426, 9 pis., 1864) [also published as a separate: Krpyer, H. 1863. Bidrag til kundskab om snyltekrebsene. Thieles Bogtrykkeri, Kjpbenhavn, 352 p., 18 pis.]. Martinez-Palacios, C.A. and L.G. Ross. 1988. The feeding ecol- ogy of the Central American cichlid Cichlasoma urophthal- mus (Gunther). Journal of Fish Biology 33:665-670. Martinez-Palacios, C.A. and L.G. Ross. 1992. The reproductive biology and growth of the Central American cichlid Cichlasoma urophthalmus (Gunther). Journal of Applied Ichthyology 8:99-109. Masson, M. and C. Delamare Deboutteville. 1962. Etudes sur les crustaces branchioures d’ Europe. IT Les caracteres sexuels du male chez Argulus giordanii Brian et chez A. arcassonen- sis Cuenot. Bulletin du Museum National d’Histoire Naturelle (2e Serie) 34:387-396. Meehean, O.L. 1940. A review of the parasitic Crustacea of the genus Argulus in the collections of the United States National Museum. Proceedings of the United States National Museum 88(3087):459-522. Moravec, E, M.I. Jimenez-Garcia and G. Salgado-Maldonado. 1998. New observations on Mexiconema cichlasomae (Nematoda: Dracunculoidea) from fishes in Mexico. Parasite 5:289-293. Moravec, F, V. Vidal-Martinez and L. Aguirre-Macedo. 1999. Branchiurids {Argulus) as intermediate hosts of the dani- conematid nematode Mexiconema cichlasomae. Folia Parasitologica 46:79. Overstreet, R.M., 1. Dykova and W.E. Hawkins. 1992. Branchiura. In: F.W. Harrison and A.G. Humes, eds. Microscopic Anatomy of the Invertebrates, Vol. 9 Crustacea. Wiley-Liss, Inc., New York, NY, USA, p. 385-413. Pineda, R., S. Paramo and R. Del Rio. 1995. A new species of the genus Argulus (Crustacea: Branchiura) parasitic on Atractosteus tropicus (Pisces: Lepisosteidae) from Tabasco, Mexico. Systematic Parasitology 30:199-206. Poly, W.J. 2003. Argulus ambystoma, a new species parasitic on the salamander Ambystoma dumerilii from Mexico (Crustacea: Branchiura: Argulidae). Ohio Journal of Science 103:52-61. Rupp, M.B. 1990. An abbreviated method for preparing Ixodes damini ticks for scanning electron microscopy observation. Journal of Electron Microscopy Technique 15:99-100. Salgado-Maldonado, G. and C.R. Kennedy. 1997. Richness and similarity of helminth communities in the tropical cichlid fish Cichlasoma urophthalmus from the Yucatan Peninsula, Mexico. Parasitology 114:581-590. Van As, J.G., J.P Van Niekerk, and P.A.S. Oliver. 1999. Description of the previously unknown male of Argulus kosus Avenant-Oldewage, 1994 (Crustacea: Branchiura). Systematic Parasitology 43:75-80. Vidal-Martinez, V.M., C.R. Kennedy, and M.L. Aguirre-Macedo. 1998. The structuring process of the macroparasite commu- nity of an experimental population of Cichlasoma uroph- thalmus through time. Journal of Helminthology 72:199-207. Wilson, C.B. 1902. North American parasitic copepods of the family Argulidae, with a bibliography of the group and a systematic review of all known species. Proceedings of the United States National Museum 25(1302):635-742, 23 figs., 2 pis. Wilson, C.B. 1936a. Copepods from the cenotes and caves of the Yucatan Peninsula, with notes on cladocerans. Carnegie Institution of Washington, Publication No. 457:77-88, 18 figs. Wilson, C.B. 1936b. Two new parasitic copepods from Cuban fish. Memorias de la Sociedad Cubana de Historia Natural “Eelipe Poey” 10:107-112. Yamaguti, S. and T. Yamasu. 1959. On two species of Argulus (Branchiura, Crustacea) from Japanese fishes. Biological Journal of Okayama University 5:167-175. 13 Gulf and Caribbean Research Volume 17 Issue 1 January 2005 Fishery and Biology of Blackfin Tuna Thunnus atlanticus off Northeastern Brazil Katia M.F. Freire University of British Columbia Rosangela Lessa Universidade Federal Rural de Pernambuco, Brazil Jorge Eduardo Lins-Oliveira Universidade Federal do Rio Grande do Norte, Brazil DOI: 10.18785/gcr.l701.02 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Freire, K. M., R. Lessa and J. E. Lins-Oliveira. 2005. Fishery and Biology of Blackfin Tuna Thunnus atlanticus off Northeastern Brazil. Gulf and Caribbean Research 17 (l); 15-24. Retrieved from http:// aquila.usm.edu/gcr/voll7/iss 1/2 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf and Caribbean Research Vol 17, 15-24, 2005 Manuscript received July 13, 2004; accepted December 2, 2004 FISHERY AND BIOLOGY OF BLACKFIN TUNA THUNNUS ATLANTICUS OFF NORTHEASTERN BRAZIL Katia M.F. Freire^, Rosangela Lessa^, and Jorge Eduardo Lins-Oliveira^ ^Fisheries Centre, University of British Columbia, 2259 Lower Mall, Vancouver-BC-Canada, V6T 1Z4, E-mail k.mfreire@fisheries.ubc.ca ^Laboratorio de Dindmica de Populagdes, Departamento de Pesca, Universidade Federal Rural de Pernambuco, Rua Manuel de Medeiros, S/N, Dois Irmdos, Recife-PE-Brazil, CEP: 52.171-900 ^Departamento de Oceanografia, Universidade Federal do Rio Grande do Norte, Via Costeira, S/N Parque das Dunas, Natal-RN-Brazil, CEP 59.090-001 ABSTRACT Blackfin tuna, Thunnus atlanticus, is the target species of a handline artisanal fishery off northeastern Brazil in September-January, but it is also caught by anglers and as by-catch in industrial fisheries. The population structure, morphometric relationships, mortality, reproduction, and fishery dynamics were studied during 2 fishing seasons (1996 and 1997). The maximum length and weight observed were 87 cm FL and 10 kg W^, respectively. Males were larger and predominant (1.9:1). The length at 50% maturity was 49.8 cm FL for females and 52.1 cm FL for males. This species uses the area for reproduction, although a spawning peak was not observed. The length at first capture (58.1 cm FL) was higher than the length at 50% maturity. The total, natural, and fishing mortality rates were 2.34, 0.94, and 1.40 yeai~i, respectively. The total length-fork length and the total length- standard length relationships were TL = 1.35369 + 1.0462 FL and TL = 6.37742 + 1.0544 SL, respectively (sexes grouped). The length- weight relationship estimated for both sexes was Wd = 0.00003 FL2-8569. Annual catches decreased from 154 t year-1 the 1970s to 33.5 t yeai—l in the 1990s. It seems that there was not much change in the structure of this stock after 30 years, but the lack of a proper collection system of catch data and the increasing interest in recreation- al fisheries raise reasons for concern. RESUMEN El Atun aleta negra, Thunnus atlanticus, es capturado por una pesqueria artesanal en el noreste de Brasil de septiembre a enero, pero tambien por Pescadores recreacionales y como fauna acompanante en pesquerias indus- triales. La estructura de la poblacion, relaciones morfometricas, mortalidad, reproduccion y dinamica pesquera fueron estudiadas durante dos temporadas de pesca (1996 y 1997). La longitud y el peso maximos observados fueron 87 cm FL y 10 kg W^, respectivamente. Los machos fueron mayores y predominantes (1.9:1). El tamano al 50% de madurez fue 49.8 y 52.1 cm FL para machos y hembras, respectivamente. Esta especie usa la region para reproduccion, aunque un pico de desova no fue observado. El tamano en la primera captura (58.1 cm EL) fue mas alto que el tamano al 50% de madurez. La mortalidad total, natural, y por pesca fueron 2.34, 0.94 y 1.40 ano-1, respectivamente. Las relaciones longitud total-longitud furcal y longitud total-longitud estandar fueron: TL = 1.35369 + 1.0462 EL y TL = 6.37742 + 1.0544 SL, respectivamente (sexos agrupados). La relacion peso-longitud estimada para ambos los sexos fue de = 0.00003 EL2-8569 l^s capturas anuales disminuyeron de 154 t ano-1 en la decada de los 70s a 33.5 t ano-1 en la decada de los 90s. Los resultados parecen indicar que no ha habido mucho cambio en la estructura de este estoque despues de treinta anos, pero la carencia de un sistema apropiado de la obtencidn de datos de captura y el interes de las industrias pesqueras recreacionales son motivo de preocupacidn. Introduction Blackfin tuna, Thunnus atlanticus, occur only in the western Atlantic Ocean, from Martha’s Vineyard/US — 40°N to Rio de Janeiro/Brazil — 22°S, including the Gulf of Mexico and the Caribbean (Collette and Nauen 1983). Zavala-Camin (1991), however, recorded this species as far as 31°S (southern Brazil). Blackfin tuna reach a maxi- mum size of 108 cm, which is much smaller than other Thunnus species (www.fishbase.org). In the Caribbean region, this species supports impor- tant fisheries mainly in Venezuela, Martinique, Guadeloupe, Cuba, and Dominican Republic (FISHSTAT; www.fao.org). Off southern and northeastern Brazil, blackfin tuna are by-catch in longline fisheries targeting Thunnus albacares, Thunnus obesus, Thunnus alalunga, Xiphias gladius, and Carcarhinidae. Bata Formosa, a fish- ing village located in the south of Rio Grande do Norte State, is the only area in Brazil where significant aggrega- tions of T. atlanticus are found close enough to the main- land to justify a handline artisanal fishery from September to January (Cruz and Paiva 1964). This fishery is important to the local economy, where almost 100% of the artisanal catch of ‘albacore’ is Thunnus atlanticus. Catches are con- sumed locally or sold to neighbour states: Parafba and Pernambuco (Tartari 1966). The artisanal fishery targeting blackfin tuna in Brazil cannot be properly analyzed because national and local databases record this species as albacore (‘albacora’) together with 3 other species {T. albacares, T alalunga, and T. obesus). Indeed, Freire 15 Freire et al. (2003), in compiling a national landing database, noted that albacore is caught by both artisanal and industrial fish- eries in 14 out of the 17 Brazilian coastal states. However, blackfin tuna (‘albacorinha’) is recorded as being caught only after 1994 by industrial fisheries in 3 states in south- ern Brazil (Sao Paulo, Rio de Janeiro, and Santa Catarina). No catch is recorded for this species in northeastern Brazil. Information on the biology and fishery of blackfin tuna is available primarily for the Caribbean (Carles 1974, Garcia-Coll 1987a, Carles and Valle 1989, Baez-Hidalgo and Becquer 1994, Taquet et al. 2000, Doray et al. 2004) and for Brazil in earlier periods (Cruz and Paiva 1964, Monte 1964a, b, Cruz 1965, Nomura and Cruz 1966). This study aims to update information on the fishery and population structure of Thunnus atlanticus off north- eastern Brazil. In particular, we document overall catches, yield per boat per trip, length-frequency distribution, sex ratio, basic morphometric relationships, mortality rates, and length at 50% maturity and at first capture. Materials and Methods A sampling program was established in Baia Formosa, Rio Grande do Norte/Brazil (6°22'S and 35°00'W; Figure 1), during September 1996-January 1997 and September 1997-January 1998, the first sampling period following more than thirty years without data collection from com- mercial fisheries — artisanal or industrial. This program was divided into 2 parts: size sampling, where measures of fork length (cm; FL) and gutted weight (kg; = weight with no viscera or gills) of blackfin tuna Thunnus atlanti- cus were taken daily, and biological sampling, where we measured weekly total length (cm; TL), FL (cm), and (kg), determined sex, and collected gonads. All samples were taken in the 5 market places concen- trated in the only landing port of the region. In both sam- pling programs, all individuals caught by each boat were sampled up to an overall total of 30 fishes per sampling day (some boats catch daily only 2-3 individuals). This dataset was complemented with TL and standard length (SL) data from the REVIZEE Program/NE Score (Assessment of Renewable Resources off the Brazilian Exclusive Economic Zone/Northeastern Score) for the period 1998-2000. Catch data per boat per trip for black- fin tuna were obtained from receipts available at the Baia Eormosa Eishing Cooperative (1996-1998) and comple- mented with data from national and local statistical bul- letins (CEPENE, 2000; Ereire, 2003). Erequency distributions of EE were calculated for males and females. TE-EE and W^-EL relationships were estimated for males and females separately, with a log- transformation of and EE for the latter. A SE-TE rela- tionship was calculated for males and females combined, as sex information was not available for specimens with recorded SE. The total instantaneous mortality rate was estimated based on the catch-curve for EE converted to age using von Bertalanffy growth parameters for blackfin tuna estimated using the routine EEEEAN I — Electronic Eength- Erequency Analysis available in EISAT II — EAO- ICEARM Stock Assessment Tools (http://www.fao.org/ fi/statist/fisoft/fisat/index.htm; Gayanilo and Pauly, 1997). This routine identified the growth curve that best fitted the set of length-frequency data for blackfin tuna obtained from the size sampling previously described. The natural mortality rate (M) was estimated based on the following simplified equation: where: E,^ = asymptotic length (TE; cm), K = curvature parameter of the von Bertalanffy growth curve (year“^), and Tc = mean water temperature (°C) (Pauly 1980). A mean sea-surface temperature of 27.2 °C was estimated for the fishing seasons of 1996 and 1997, based on the data available from the International Comprehensive Ocean- Atmosphere Data Set — ICOADS (http://dss.ucar.edu/ pub/coads/). The mean size at first capture was estimated by fitting a logistic curve to the ascending limb of the length-converted catch curve and defining the size at which 50% of the individuals are caught (E^q). Maturity stages were defined macroscopically using the following scale: 1 = immature; 2 = resting; 3 = active; 4 = ripe (actual spawning condition); and 5 = spent (Jolley 1977). The weight of the gonads was measured (0.001 g) and the gonadosomatic index (GSI) was calculated for females and males as: GSI = (Wg x 100)/W(j, where Wg = gonadal weight (g) and = gutted weight (g). The length at maturity was estimated for females and males as the length at which 50% of all individuals are mature. It is worth mentioning here that, although individuals are evis- cerated on board (Nomura and Cruz 1966), this process involves removal of gills and viscera through the opercu- lum, leaving the gonads intact. Hence, it is still possible to determine the sex and reproductive condition of eviscerat- ed fish. Eength-frequency distributions for males and females were compared using a Chi-square test. Sex ratios were tested against the null hypothesis of 1:1 for each month using a Chi-square test. Eength-weight and length-length relationships for males and females were compared using a t-statistic to test for both slope and intercept (Zar, 1984). 16 Blackfin Tuna off Northeast Brazil Figure 1. Location of sampling areas in northeastern Brazil. The black circle corresponds to Baia Formosa (6°22'S and 35°00'W), and the gray circles are areas where samples were collected through the REVIZEE Program/Score NE (MA = Maranhao, PI = Piaui, CE = Ceara, RN = Rio Grande do Norte, PB = Paraiba, PE = Pernambuco, AL = Alagoas, SE = Sergipe, BA = Bahia). RJ = Rio de Janeiro, SP = Sao Paulo, SC = Santa Catarina. In the bottom-right are the countries with the highest catches of blackfin tuna in the Caribbean. All statistical tests were performed with a significance level of 0.05. Results From 1993 to 2001, blackfin tuna catches from the artisanal fleet operating in Baia Formosa ranged from 16.8 to 48.6 tonnes, with an annual mean of 33.5 tonnes. This estimate was obtained considering that 100% of ‘albacore’ catches in that region are actually blackfin tuna. The mean catch of blackfin tuna per boat per fishing trip was 35.3 kg for 1996-1997, with an increasing trend towards the end of the fishing season when the yield reached 50.7 kg. Length- frequency distributions for males and females were statis- tically different ( 2= 71 . 6 ; DF = 23; P< 0.0001), with males reaching a larger size (Figure 2). Analysis of monthly length-frequency distributions indicates that larger individuals reach the region in September and are followed later by a second mode of smaller individuals (Figure 3). The smallest observed indi- vidual was 23 cm FL and the smallest observed weight was 0.8 kg (Table 1). The maximum length and weight 17 Freire et al. Figure 2. Length-frequency distribution for Thunnus atlanti- cus off Baia Formosa, northeastern Brazil (1996-1998). ”males “ "females “ observed were 87 cm FL, and 10 kg respectively. Males predominated in a ratio of 1.9:1 (Table 2). Although this proportion varied during the fishing season, males were always predominant as indicated by the chi-square test, with the exception of the sample collected in January 1997. In this sample, the sex ratio was not significantly dif- ferent from 1:1. The relationships between TL and FL for females and males were not statistically different (tg^gpe “ ~ 336, and P = 0.090; tjj^tercept “ ~ ^ ~ 0.094). The resulting relationship obtained for both sexes combined was: TL = 1.35369 + 1.0462 FL (Table 3). The relationship between TL and SL estimated for the sexes combined was: TL = 6.37742 + 1.0544 SL (Table 3). The relationships between and FL for males and females were statistically different, with males heavier at size (Table 3; tgjQpg = 2.16, DF = 613, and P = 0.031; tjj^tgj-. cept “ 2.24, DF = 614, and P = 0.025). The weight-length relationship for unsexed individuals from our sampling area is: = 0.00003 FL2-8569 (^ = o.92, ^ = 617, P< 0 . 0001 ). The von Bertalanffy growth curve parameters estimat- ed based on the length-frequency distribution was: L. = 92 cm (FL), K = 0.65 year“^ t^ = 0 years. The total instanta- neous mortality rate (Z) estimated was 2.34 year“^ (Confidence interval (Cl) = [L92;2.77]; Figure 4). The natural mortality rate calculated was 0.94 year~^ which implies a fishing mortality of 1.40 year“^ and an exploita- tion rate of 59.7%. The average length at first capture was 58.1 cm FL (sexes grouped; Figure 5). The length at 50% maturity was greater for males (52.1 cm FL) than for females (49.8 cm FL) (Figure 6). The gonadosomatic index (GSI) for females did not show a clear pattern between years (Figure 7). For males, high- est values of GSI were observed in December in both years. Macroscopic identification of maturity stages for females indicates that this species uses the area for repro- duction, with active individuals observed as early as September or October (Figure 8). One month later running ripe individuals were observed, with some inter-annual variation. Discussion Blackfin tuna catches from Baia Formosa were much lower in 2001 (48.6 tonnes) than in 1969-1977 (52 to 296 tonnes, with an average of 154 tonnes year“^; Vasconcelos and Conolly 1980). Current catches are also lower than catches from industrial fisheries off southeastern Brazil (annual average of 172 tonnes year“^ for 1995-2000; Freire 2003). However, the social importance of the arti- sanal fishery is higher, as the local community largely depends on this fishery. The mean yield per boat per fishing trip in 1963 was 34.9 kg (Cruz and Paiva 1964b). The yield increased to 39.3 kg in 1977 (68 boats, Vasconcelos and Conolly 1980) but decreased to 38.5 kg in 1996 (this study). These differ- ences cannot be attributed to changes in gear selectivity; 80-140 cm long handline has been used for the last 40 years with a no. 15 hook attached to the end of the line (Vasconcelos and Conolly 1980; Joao C. Neto, Baia Formosa Fisher’s Association, pers. com.). The only change observed during this period was the introduction of motorized boats in 1967-1968, which could account for the yield per trip being higher in the 1970s than in the early 1960s. Although these boats operate in the same fishing ground as sailboats, 12 to 16 miles from the coast (Vasconcelos and Conolly 1980), their fishing trips are longer (3-5 days versus 1 day for sailboats) and their crew is larger (4 fishers versus 3) (Joao C. Neto, pers. com.), thus producing higher yield per trip. Total blackfin tuna mortality decreased from 3.16 year“^ in 1965 (based on Nomura and Cruz 1966) to 2.66 year“^ in 1977 (based on Vasconcelos and Conolly 1980) and declined again to 2.34 year“^ in 1996, even though the latter twoare not statistically different. More effort should be put into the collection of catch and effort data for this fishery since fishing mortality is estimated at 1.40 year“^ with an exploitation rate of about 60%, which may not be sustainable. On the other hand, a length at first capture greater than the length at 50% maturity may contribute to the future sustainability of this fishery. Although the natu- ral mortality obtained in this study is similar to those for other Thunnus species, there could be a size-dependence as pointed out by Hampton (2000) for T. albacares and T. obesus. Blackfin tuna use the Baia Formosa area for reproduc- tion, although we could not define a distinct reproductive peak using GSI or macroscopically-defmed maturity 18 Blackfin Tuna off Northeast Brazil >, 160 r o c (D 5 . 120 - S 80 - £ 40 - < 0 Sep 96 I h-HiTlTl-H l-l M 23 31 39 47 55 63 71 79 87 160 r 120 - 80 - 40 - 0 23 31 Jan 98 I I I I i_] 39 47 55 63 71 79 87 Fork length (cm) Fork length (cm) Figure 3. Monthly length-frequency distribution for Thunnus atlanticus off Baia Formosa (1996-1998; both sexes combined n = 5315). 19 Freire et al. TABLE 1 Minimum, mean, and maximum size of Thunnus atlanticus off Baia Formosa sampled from September 1996- January 1998. TL = total length (cm), FL = fork length (cm), W^j = gutted weight (kg), SD = standard deviation, N = sample size. TL Unsexed FL Wd TL Females FL Wd TL Males FL Wd Minimum 5inr" 0.8 5U7r" 1.5 53.0 43.0 1.5 Mean 63.8 59.4 3.3 61.2 56.1 2.7 65.2 60.2 3.4 Maximum 90.5 87.0 10.0 74.5 72.5 5.5 90.5 86.0 9.5 SD 6.9 6.2 1.2 5.9 5.9 0.8 7.0 7.3 1.2 N 357 5316 5209 no 237 no 230 457 230 TABLE 2 Number of males and females and sex ratio of Thunnus atlanticus caught off Baia Formosa by month. Jan 1998 was not included as there was no biological sampling. ^Statistically significant at = 0.05. Month Males Females Sex ratio Chi-square ( ^) P Oct 1996 30 15 2.0:1 5.0* 0.0253 Nov 1996 94 53 1.8:1 11.4* 0.0007 Dec 1996 67 31 2.2:1 13.2* 0.0003 Jan 1997 26 20 1.3:1 0.8 0.3771 Sep 1997 33 16 2.1:1 5.9* 0.0151 Oct 1997 104 47 2.2:1 21.5* < 0.0001 Nov 1997 80 44 1.8:1 10.4* 0.0012 Dec 1997 24 11 2.2:1 4.8* 0.0280 Total 458 237 1.9:1 70.3* < 0.0001 TABLE 3 Length-length and weight-length relationships for blackfin tuna Thunnus atlanticus off northeastern Brazil. TL = total length (cm); FL = fork length (cm); SL = standard length (cm); = gutted weight (kg); N = sample size; r^ = coefficient of determination; p = probability. * Linear relationship: Y = a + bX; ** Power relationship: Y = aX'^. Unknown Known a b Sex N r2 P TL* FL 0.21206 1.0678 Females no 0.98 < 0.0001 TL* FL 1.48854 1.0433 Males 230 0.99 < 0.0001 TL* FL 1.35369 1.0462 Unsexed 340 0.99 < 0.0001 TL* SL 6.37742 1.0544 Unsexed 93 0.90 < 0.0001 Wd** FL 0.00004 2.7268 Females 218 0.86 < 0.0001 Wd** FL 0.00002 2.8837 Males 399 0.94 < 0.0001 Wd** FL 0.00003 2.8569 Unsexed 617 0.92 < 0.0001 20 Blackfin Tuna off Northeast Brazil Figure 4. Length-converted catch-curve for Thunnus atlanticus off Baia Formosa (1996-1998; both sexes combined). Confidence interval (Cl) for total instantaneous mortality (Z) = [1.92; 2.77]. Figure 5. Probability of capture by handline for Thunnus atlanticus off Baia Formosa (1996-1997; both sexes combined; L^q = 58.1 cm FL). Fork length (cm) Figure 6. Sexual maturity for females (open squares) and males (solid diamonds) of Thunnus atlanticus off Baia Formosa (1996-1998; ^females “ ”males “ Dashed lines represent length at 50% maturity (49.8 and 52.1 cm FL for females and males, respectively). 21 Freire et al. 1.6 a) Females 1.4 1.2 C/)i 0 0 lu 0.8 0.6 0.4 Oct 96 Dec 96 Oct 97 Dec 97 Nov 96 Jan 97 Nov 97 1 6r b) Males g 1.2 « 1.0 0.8 0.6 0.4 Oct 96 Dec 96 Sep 97 Nov 97 Nov 96 Jan 97 Oct 97 Dec 97 Figure 7. Variation of the mean gonadosomatic index (GSI) for females (a) and males (b) of Thunnus atlanticus off Baia Formosa (1996-1997; ^females “ ”males “ 293). Whiskers represent mean + standard error. stages. In December, GSI for males was higher than for females, which is not common for tunas, but was also found in T. obesus in the Indian Ocean (Nootmorn 2004). The lack of such a peak of reproduction may be due to the pattern of immigration of this species to this region, with large individuals arriving first, followed by smaller indi- viduals, and/or to its multiple spawning feature, common- ly observed in tunas (Schaefer 2001). This author points out that sea-surface temperatures (SST) higher than 24 °C are associated with spawning activity for all tuna species. Indeed, local SST was in excess of 26 °C during the whole sampling period (http://dss.ucar.edu/pub/coads/), which would reinforce the hypothesis of continuous spawning activity. However, there is no information on the occur- rence of larvae of T. atlanticus in this region, probably due to identification difficulties for Thunnus larvae (Richards et al. 1990). In contrast to Brazil, spawning occurs year round in Cuba, with a clear peak in June-September (Valle-Gomez 1992). In southeastern US, spawning occurs from April to November (Idyll and de Sylva 1963). Males are larger than females, as also observed for nearly all tuna species (Schaefer, 2001), and mature at a slightly larger size. Although a larger maturity size for males is not common in scombrids, length at 50% maturi- ty for Katsuwonus pelamis in both Atlantic and Indian oceans was reported to be larger for males than for females (Cayre and Farrugio 1986, Stequert and Ramcharrun 1996). A detailed histological study would be able to test if this difference is real or possibly attributed to the mis- classification of maturity stages using macroscopic analy- sis. Monte (1964b) pointed out that sexual maturation for both sexes of blackfin tuna occurring in northeastern Brazil in the early 1960s begins at 50 cm FL, with a high- er frequency of ripe females at 56-65 cm FL. These values are higher than the size at 50% maturity estimated in this study. Such reduction in maturity size could result in short- er reproductive life span and reduced fecundity, even though a compensatory increase in mean individual fecun- dity has been observed for some species (Jennings et al. 2001). There are no conclusive data on the length at 50% maturity for the Caribbean, except for an indication of sex- ual differentiation occurring in individuals 39 cm long in Cuba (Carles 1971) and an indication that individuals smaller than 41 cm are immature in Martinique (Taquet et al. 2000). Males were predominant off Baia Formosa in 1996 (1.9:1) as they were in the 1960s (1.6:1; Monte 1964b), with some variation during the fishing season. A predomi- nance of males was also observed off Cuba (1.6:1, Garcia- Coll 1987b) and off Miami (2:1, Idyll and de Sylva 1963). Although the overall sex ratio for most tuna species is 1:1, some concentration of males occur when females are reproductively active (Schaefer 2001), as observed here. In addition to the apparent reduction in the length at 50% maturity for females, their mean size also decreased by about 1.5 cm FL in 34 years. However, smaller and big- ger individuals were sampled in 1996-1997 (23-87 cm FL; this study) than in 1963-64 (51-80 cm FL, Monte 1964b), 1965-1966 (45-79 cm FL, Nomura and Cruz 1966) and 1977 (36.5-81.5 cm FL, Vasconcelos and Conolly 1980). These observed changes cannot be attrib- uted to gear selectivity, as gear has remained the same dur- ing this period. Instead, they indicate actual changes in the population and represent signs of intense exploitation, as observed, for example, for Micropogonias undulatus (Atlantic croaker) in the northwestern Atlantic (Diamond et al. 1999). However, because T. atlanticus is a migratory species, these effects are likely to be a result of local 22 Blackfin Tuna off Northeast Brazil Figure 8. Proportion of the stages of maturity for females of Thunnus atlanticus off Baia Formosa (1996-1997). Sample sizes are presented on the top of each column. exploitation combined with that from other areas in the distribution range of the stock. Some changes have been noted in the population structure, in catches, and in yield of blackfin tuna. Although these changes are not large enough to cause great concern, they should be seen as a warning sign by the national agencies in charge of fisheries management (SEAP — Special Secretary of Aquaculture and Fisheries and IBAMA — Brazilian Institute for the Environment and Renewable Resources) and should promote improved data collection for artisanal fisheries targeting small tunas. The importance of blackfin tuna in the food web of large pelag- ic fish is not well understood, as it is often difficult to iden- tify species or even genera of scombrids found in the guts of billfish, swordfish, dolphinfish, and sharks (Vaske- Junior 2000). There is also an increasing demand for oceanic recreational fisheries in the region (Freire in press), which could ultimately put more pressure on this resource. Thus, it is imperative that our understanding of blackfin tuna be improved sooner rather than later. Acknowledgments We thank Erivan B. Mendonga, Joao C. Neto, Jose Duarte Ribeiro, and Francisco Canide for helping with the collection of length and catch data. Euiana Morals, Patricia Goes, and Marcelo Mendonga, and Kacia Vieira helped with the collection and processing of the biological material, and Fabio Freire with some of the MATFAB programming involved in this paper. Juarez Rodrigues encoded part of the data and shared his knowledge about local fisheries. Jackie Alder, R.E. Matheson, and 3 anonymous reviewers provid- ed valuable comments on the manuscript. The National Council for the Scientific and Technological Development (CNPq/Brazil) granted fellowships for all authors. Literature Cited Baez-Hidalgo, M. and U. Becquer. 1994. Fecundidad del bonito Katsuwonus pelamis (Linnaeus) y la albacora Thunnus atlanticus (Lesson) en Cuba. Revista de Investigaciones Marinas 15:218-222. Carles, C. 1971. Caracteristicas biologico-pesqueras del bonito {Katsuwonus pelamis) y la albacora {Thunnus atlanticus) en la costa nororiental de Cuba. Centro de Investigaciones Pesqueras, Instituto Nacional de Pesca de Cuba, Contribucion 32:1-51. Carles, C. 1974. Edad y crecimiento del bonito {Katsuwonus pelamis) y albacora {Thunnus atlanticus) en la costa norori- ental de Cuba. Resiimenes de Investigaciones del Centro de Investigaciones Pesqueras 1:122-126. Carles, C. and S. Valle. 1989. Analisis de las pesquerias de lista- do {Katsuwonus pelamis) y de atun aleta negra {Thunnus atlanticus) en el Atlantico Occidental. Collective Volume of Scientific Papers, ICCAT 30(l):47-55. Cayre, P. and H. Farmgio. 1986. Biologie de la reproduction du listao (Katsuwonus pelamis) de f Ocean Atlantique. In: Symons P.E.K., PM. Miyake and G.T. Sakagawa (eds.). Proceedings of the ICCAT Conference on the International Skipjack Year Program. ICCAT, Madrid, Spain, p. 252-272. CEPENE 2000. Boletim estatistico da pesca maritima e estuarina do nordeste do Brasil 1999. Centro de Pesquisa e Extensao Pesqueira do Nordeste/IBAMA, Tamandare, 150 p. Collette, B.B. and C.E. Nauen. 1983. FAO species catalogue. Vol. 2. Scombrids of the world. An annotated and illustrated cat- alogue of tunas, mackerels, bonitos and related species known to date. FAO Fisheries Synopsis 125(2): 1-137. Cruz, J.F. 1965. Contribuigao ao estudo da biologia pesqueira da albacora Thunnus atlanticus (Lesson), no nordeste do Brasil. Boletim do Instituto de Biologia Marinha da Universidade do Rio Grande do Norte:33-40. Cruz, J.F. and M.P Paiva. 1964. Sobre a biologia pesqueira da albacora, Thunnus atlanticus (Lesson), no nordeste do Brasil. Boletim do Instituto de Biologia Marinha da Universidade do Rio Grande do Norte 1:1-17. 23 Freire et al. Diamond, S.L., L.B. Crowder, and L.G. Cowell. 1999. Catch and bycatch: The qualitative effects of fisheries on population vital rates of Atlantic croaker. Transactions of the American Fisheries Society 128:1085-1105. Doray, M., B. Stequert, and M. Taquet. 2004. Age and growth of blackfin tuna (Thunnus atlanticus) caught under moored fish aggregating devices, around Martinique Island. Aquatic Living Resources 17:13-18. Freire, K.M.F. 2003. A database of landing data on Brazilian marine fisheries from 1980 to 2000. Fisheries Centre Research Report 11(6):181-189. Freire, K.M.F. in press. Recreational fisheries of northeastern Brazil: inferences from data provided by anglers. Proceedings of the 21st Wakefield Fisheries Symposium, October 22-25, 2003, Anchorage, Alaska, USA. Garcia-Coll, I. 1987a. Composiciones por largo de bonito (Katsuwonus pelamis) y albacora {Thunnus atlanticus) en dos regiones de Cuba. Revista de Investigaciones Marinas VIII:69-81. Garcia-Coll, I. 1987b. Relaciones largo-peso y proporcion de sexos del bonito {Katsuwonus pelamis) y la albacora {Thunnus atlanticus) de Cuba. Revista de Investigaciones Marinas VIII: 83-97. Gayanilo, F.C. and D. Pauly. 1997. FAO-ICLARM stock assess- ment tools (FIS AT). Reference manual. FAO Computerized Information Series (Fisheries), 262 p. Hampton, J. 2000. Natural mortality rates in tropical tunas: size really does matter. Canadian Journal of Fisheries and Aquatic Science 57:1002-1010. Idyll, C.P and D. de Sylva. 1963. Synopsis of biological data on the blackfin tuna Thunnus atlanticus (Lesson) 1830 (Western Atlantic). FAO Fisheries Biology Synopsis 68:761-770. Jennings, S., M.J. Kaiser, and J.D. Reynolds. 2001. Marine fish- eries ecology. Blackwell Science, Oxford, UK, 417 p. Jolley, J.W. 1977. The biology and fishery of Atlantic sailfish Istiophorus platypterus, from southeast Florida. Florida Marine Research Publications 28:1-31. Monte, S. 1964a. Algumas observagoes sobre a reprodugao da albacora, Thunnus atlanticus (Lesson). Boletim do Instituto de Biologia Marinha da Universidade do Rio Grande do Norte 1:1-20. Monte, S. 1964b. Observagoes sobre a estrutura histologica das gonadas da albacora, Thunnus atlanticus (Lesson), no nordeste do Brasil. Boletim do Instituto de Biologia Marinha da Universidade do Rio Grande do Norte 1:17-31. Nomura, H. and J.F. Cruz. 1966. On the length and weight of Thunnus atlanticus (Lesson) from northeastern Brazil. Boletim do Instituto de Biologia Marinha da Universidade do Rio Grande do Norte 3:33-37. Nootmorn, P. 2004. Reproductive biology of bigeye tuna in the eastern Indian Ocean. lOTC, Victoria, Seychelles, 13-21 July 2004. Proceedings no.7:l-5. Pauly, D. 1980. On the interrelationships between natural mortal- ity, growth parameters, and mean environmental tempera- ture in 175 fish stocks. Journal du Conseil International pour I’exploration de la Mer 39:175-192. Richards, W.J., T. 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Collective Volume of Scientific Papers, ICCAT 39(1): 12-26. Vasconcelos, J.A. and PC. Conolly. 1980. A study of some bio- logical aspects of the fishing of blackfin tuna {Thunnus atlanticus, Lesson) in the state of Rio Grande do Norte. Collective Volume of Scientific Papers, ICCAT 9(3):734-738. Vaske-Junior, T. 2000. Relagoes trdficas dos grandes peixes pelagicos da regiao equatorial sudoeste do Oceano Atlantico. Fundagao Universidade do Rio Grande, Departamento de Oceanografia, Rio Grande, Brazil, 144 p. Zar, J.H. 1984. Biostatistical Analysis. 2nd ed., Prentice Hall, Englewood Cliffs, New Jersey, USA, 718 p. Zavala-Camin, L.A., R.T.B. Grassi, R.W.V. Seckendorff, and G.G. Tiago. 1991. Ocorrencia de recursos pesqueiros epipelagicos na posigao 22°irS, 039°55'W, Brasil. Boletim do Instituto de Pesca 18:13-21. 24 Gulf and Caribbean Research Volume 17 Issue 1 January 2005 Coastal Origin of Common Snook^ Centropomus undecimalis, in Florida Bay Heather M. Patterson University of Melbourne Ronald G. Taylor Florida Marine Research Institute Richard S. McBride Florida Marine Research Institute DOI; 10.18785/gcr.l701.03 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Patterson, H. M., R. G. Taylor and R. S. McBride. 2005. Coastal Origin of Common Snook, Centropomus undecimalis, in Florida Bay. Gulf and Caribbean Research 17 (l): 25-30. Retrieved from http:/ / aquila.usm.edu/ gcr/voll7/issl/3 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf and Caribbean Research Vol 17, 25-30, 2005 Manuscript received October 18, 2004; accepted January 2, 2005 COASTAL ORIGIN OF COMMON SNOOK, CENTROPOMUS UNDECIMALIS, IN FLORIDA BAY Heather M. Patterson^, Ronald G. Taylor^, and Richard S. McBride^ ^ Department of Zoology, University of Melbourne, Victoria 3010 Australia, Phone (+61 3) 8344 7986, Fax (+61 3) 8344 7909, E-mail hmpatt@unimelb.edu.au ^Florida Marine Research Institute, Florida Fish and Wildlife Conservation Commission 100 Eighth Avenue SE, St. Petersburg, Elorida 33701-5095 USA ABSTRACT We used the elemental signatures of otoliths to investigate the coastal origin of common snook (Centropomus undecimalis) in Florida Bay, Florida and evaluate current management boundaries. We examined juvenile otoliths from Florida’s Atlantic and Gulf of Mexico (Gulf) populations and determined that there were sig- nificant differences in several elemental ratios (Mn/Ca, Cu/Ca, Sr/Ca, Ba/Ca). In addition, a discriminant function analysis (DFA) indicated a significant separation between the juveniles from each coast and otoliths were never mis- classified by coast, indicating a distinct difference in their otolith chemistry. Using only juvenile otoliths to derive a calibration function, a separate DFA indicated that the adults from Florida Bay likely originated from both coasts of Florida in roughly equal proportions. Although these preliminary results contradict tagging studies, they concur with genetic studies suggesting that both east and west coast populations contribute to the common snook found in Florida Bay. Introduction The effective management of marine species requires some knowledge of the source of recruits to the popula- tion. Despite the importance of such information, discern- ing the origin of individuals can often be quite difficult, as many marine species have larvae or juveniles that can widely disperse, thereby creating demographically open populations (Roughgarden et al. 1988). Conventional tech- niques such as genetics and mark-recapture have often proven inadequate in identifying recruitment source either due to low resolution (e.g., < 1% exchange renders popu- lations genetically homogeneous; Kimura and Maruyama 1971) or logistical problems (e.g., tagging and recapturing larvae/juvenile that can disperse vast distances and suffer high mortality; Thorrold et al. 2002). In this paper we examine the issue of the coastal origins of common snook, Centropomus undecimalis, an economically and ecologi- cally important species, using otolith chemistry. Common snook are long-lived (21 years), late-matur- ing (4-5 years) protandric hermaphrodites that are distrib- uted along the coasts of Florida’s Atlantic Ocean (Atlantic) and Gulf of Mexico (Gulf) (Taylor et al. 1998, 2000). This gamefish supports valuable sport fisheries throughout its range and contributes substantially to Florida’s economy (Tucker et al. 1985). Adult common snook support popular fisheries in the Florida Keys and adjoining Everglades National Park (Figure 1, Tilmant et al. 1989), but the source of recruits to this area remains unknown. Several studies have reported collecting common snook in Florida Bay (Tabb and Manning 1961, Tabb et al. 1962, Roessler 1970). However, none recorded the sizes of the individuals and it is likely that these records are of adults because of the high salinities of the waters in which they were collect- ed. No eggs, larvae, or juvenile common snook were found in several other studies in Florida Bay (Rutherford et al. 1986, Collins and Finucaine 1987, Powell et al. 1989, Ley et al. 1999), suggesting that the major source of recruit- ment to the adult stock in this region originates elsewhere. Tringali and Bert (1996) examined the genetic stock structure of common snook throughout its range and found that Atlantic and Gulf populations were reproductively iso- lated. Their data showed that adult common snook from the western portion of Florida Bay exhibit transitional properties of both populations and suggested that adult common snook in that area were recruited from both coasts of Florida. Tagging studies, however, have indicat- ed that the Atlantic population is the most likely source of common snook in Florida Bay (Peters 1993, Bruger and Whittington, unpublished data). Water masses vary in their chemical composition in both time and space. During otolith growth, elements from seawater can substitute for calcium in the otolith matrix (Campana 1999). Thus, otoliths have the potential to act as natural tags. Otolith trace element signatures have been useful in delineating stocks (Campana et al. 1994, Patterson et al. 1999, 2004), distinguishing juvenile nurs- ery areas (Gillanders and Kingsford 2000, Forrester and Swearer 2002), and examining natal homing and self- recruitment (Swearer et al. 1999, Thorrold et al. 2001). The objective of this study was to further investigate the coastal origin of common snook in Florida Bay as con- siderable research effort has yet to provide a clear under- standing of the source of adult common snook in the Florida Bay assemblage. In addition, we wanted to evalu- ate the current fisheries management boundaries of com- 25 Patterson et al. Figure 1. Map of Florida depicting the three sampling locations: Charlotte Harbor (CH), Tequesta (TQ), and Florida Bay (FB). mon snook in Florida Bay based on our findings. We chose to take a new approach to the issue of common snook ori- gin and examined the chemistry of juvenile common snook otoliths from both Atlantic and Gulf populations, as well as the otolith cores from adult common snook in Florida Bay. Because otolith chemistry primarily reflects the chemistry of the water in which the fish resides (Bath et al. 2000), the elemental composition of the cores of adult common snook otoliths should bear the signatures of their natal estuary. The results of this type of investigation may iden- tify not only the coastal origin of the recruits to Florida Bay, but also may be used to quantify the relative contribu- tions of Atlantic and Gulf stem populations if mixing of these populations occurs. Methods Sample collection Young-of-the-year common snook (n = 20 per loca- tion; 93-250 mm SL) were collected by seine and hook and line during March-July 1999 in the vicinity of Tequesta and Charlotte Harbor on the Atlantic and Gulf coasts of Florida; these 2 locations represented Atlantic coast and Gulf coast common snook populations (Figure 1). The common snook were frozen whole until all the samples from these 2 locations were collected. Adult com- mon snook (n = 20; 306-615 mm SL) from northeastern Florida Bay were captured during September-December 1999 (Figure 1). The otoliths were removed in the field, rinsed, and stored dry. Due to the limited number of adults available, it was not possible to match adults and juveniles by year class. 26 CeNTROPOMUS UNDECIMALIS IN FLORIDA BAY TABLE 1 Mean elemental ratios (± SE) in the otoliths of common snook, Centropomus undecimalis, from each of the 3 sam- pling locations (n = 20). Ratios are given in pmol/mol Ca. Elemental Ratio Florida Bay Tequesta Charlotte Harbor Mg/Ca 125.70 ± 4.73 122.74 + 5.08 130.92 + 5.12 Mn/Ca 4.54 ± 0.41 2.88 + 0.20 4.94 + 0.30 Cu/Ca 0.26 ± 0.022 0.16 + 0.0078 0.19 + 0.013 Zn/Ca 0.72 ± 0.099 0.56 + 0.060 0.52 + 0.034 Sr/Ca 2249 + 115 3094 + 30 3865 + 66 Ba/Ca 2.18 + 0.29 1.40 + 0.41 2.65 + 0.3 Sample preparation and analysis Sample preparation and analysis procedures are simi- lar to those described in Patterson et al. (2004). Juvenile otoliths were polished evenly on all sides with 220 -grit size lapping paper until the remaining core section weighed about 10 mg. Adult otoliths from Florida Bay were first sectioned with a Buehler Isomet low-speed saw and were then polished using the method described above. The weights of the otolith sections used in the analysis did not differ (ANOVA, F2 57 = 2.37, P > 0.05). To remove surface contamination, all the sections were then acid washed in 1% ultrapure HN03 for 15 seconds and triple- rinsed in Milli-Q water. They were then dried in a class 100 laminar flow hood for 24 h and weighed to the nearest 10 pg. The otoliths were then placed in 0.5 ml of 70% ultrapure HNO 3 and dissolved for analysis. The final vol- ume was brought up to 5 ml with Milli-Q water. Blanks were prepared in the same manner to calculate limits of detection (LOD) and for blank corrections. Elemental concentrations of the otoliths were deter- mined using a Perkin-Elmer Elan 5000 inductively cou- pled plasma mass spectrometer (ICP-MS). Preliminary tests indicated that 7 elements (^^Mg, ^^Mn, ^^Ca, ^^Cu, ^^Zn, ^^Sr, and ^^^Ba) were detectable and suitable for ICP-MS analysis. Sample order was blocked so that one otolith from each location was sampled in turn, with the order within each block randomized. Internal standards for each element were used and referenced against ^^Sc, ^^Ge, and ^^^Tb. Instrument drift was monitored by analyz- ing a calibration verification solution every 20 samples; acceptable recovery was ± 10 % of the expected value. Precision was typically < 5% relative standard deviation (RSD) for Ca and Sr and < 10% for trace elements. The EOD for each element was calculated from the prepared blanks as 3 plus the mean blank value with the following results (in pg g-^): 126, 0.43, 0.04, 0.29, ^^Mn 0.08, and ^^Zn 0.04, ^^Cu 0.03. Observed val- ues were well above the EOD. Statistical analysis Elemental data were standardized to Ca and expressed as molar concentrations. The assumption of homogeneity of variances in elemental data was tested using a Cochran’s C-test and data were subsequently In (x±l) transformed. Differences between otoliths from the 2 coastal calibration sites were tested using both univariate (analysis of vari- ance; ANOVA) and multivariate (multivariate analysis of variance; MANOVA) techniques. Eor MANOVAs, Pillai’s trace was used as the test statistic as it is robust, especial- ly when variance-covariance matrices are not si mil ar (Quinn and Keough 2002). ANOVAs were performed for each elemental ratio. A Box’s M-test was used to determine the equality of vari- ance-covariance matrices and a quadratic discriminant function analysis (DEA) and jackknife cross-validation procedure were used to evaluate how accurately otoliths could be assigned to coast. Einally, otoliths from adult common snook collected from Elorida Bay were applied as the test data set to a DEA using otoliths from Tequesta and Charlotte Harbor as the calibration data set to determine to which coastal group the adults were assigned. We acknowledge that this method (DEA) creates a best case scenario and have considered this in our interpretation. Results Three of the 6 elemental ratios of otoliths from the 2 coastal locations differed significantly (Table 1; ANOVA; Mn/Ca: Ej 33 = 39.67, P < 0.05; Sr/Ca: E^ 33 = 126.41, P < 0.05; Ba/Ca: Ej 33 = 114.37, P < 0.05) and MANOVA indicated a significant difference in the multi-element sig- natures of the juvenile otoliths (Ej2 106 ~ 0.0001). In addition, a DEA depicted a clear separation between the coastal groups and otoliths were classified to coast with 100 % accuracy by a cross-validation procedure (Eigure 2). A DEA using the juvenile otoliths as a training data set and the adult cores as the test data set indicated 27 Patterson et al. <\i 0 0 CO > lo o CO O -6 -4 -2 0 2 4 6 8 Canonical variable 1 Figure 2. Canonical plot scores and 95% confidence ellipses from the discriminant analysis of multi-element signatures (Mg/Ca, Mn/Ca, Zn/Ca, Cu/Ca, Sr/Ca, and Ba/Ca) of common snook {Centropomus undecimalis) otoliths from Charlotte Harbor (cir- cles), Tequesta (black squares), and Florida Bay (triangles). that 45% and 55% of the adult cores from Florida Bay were classified as Atlantic and Gulf coasts, respectively. Discussion The geochemical signatures in the otoliths of juvenile common snook collected from the Gulf and Atlantic coasts of Florida were distinct. This difference in otolith chem- istry presumably mainly reflects the differences in water chemistry for each coast, as well as the distinct terrestrial inputs for each estuary (Bath et al. 2000). It was not possi- ble to match the juveniles and adults by year class. Although temporal variation of otolith chemistry within a location has been demonstrated in previous studies (Patterson et al. 1999, Gillanders 2002), it seems likely that overall differences in large water masses such as the Atlantic and Gulf would be temporally persistent to some degree. Indeed, elemental signatures of Gulf red drum (Sciaenops ocellatus) from several different years (1982, 1985 and 1998) were quite distinct from those of Atlantic red drum (1998 and 1999), suggesting the consistent sepa- ration of these water masses and the otolith signatures pro- duced by them (Patterson et al. 2004). We were not expecting to match the adults to estuary of origin as this would require that all potential source estuaries be characterized, a task clearly beyond the scope of this study. Instead, the results presented here are limited to identifying the coastal origin of common snook in Florida Bay and suggest that both the Atlantic and Gulf coastal areas contributed in nearly equal proportions to the adult common snook we examined. Extrapolating beyond our data set to make predictions about the relative contri- bution of each coastal population to the entire Florida Bay assemblage is not prudent at this time given the limited spatial coverage in our calibration data set. However, this preliminary finding does support the idea that both popu- lations contribute to the Florida Bay common snook assemblage. These geochemical results concur with those obtained from a genetic study that demonstrated common snook in western Florida Bay exhibited transitional properties of both Atlantic and Gulf coast stocks, and thus both stocks likely contributed to the Florida Bay assemblage (Tringali and Bert 1996). However, the required type of genetic markers (i.e., microsatellites) and likelihood-based statisti- cal methods for assigning individuals to genetically subdi- vided stocks (e.g., Wasser and Strobeck 1998) postdated their study, so relative contributions of Atlantic and Gulf populations could not be estimated. In contrast, the geochemical and genetic results do not readily agree with the available tagging data demonstrating that tagged common snook from east coast, but not west 28 CeNTROPOMUS UNDECIMALIS IN FLORIDA BAY coast locations have moved into Florida Bay. Of the 19,410 common snook tagged on the east eoast during 1984-1997, 2 were recaptured inside Florida Bay (Bruger and Whittington, unpublished data). In contrast, of the 8,655 common snook tagged on the west coast during 1976-1986, none were reported as recaptured in Florida Bay (Bruger and Whittington, unpublished data). However, the recapture ratios for each coast were not sig- nificantly different. These tagging studies were, therefore, inconclusive regarding the origin of common snook in Florida Bay. Our results derived from the geochemical signatures of common snook otoliths suggest that both Atlantic and Gulf coast populations in Florida contribute to the com- mon snook assemblage found in Florida Bay. The east- west common stock boundary for management of common snook in Florida occurs at Jewfish Creek in the Upper Keys. This boundary places common snook from Florida Bay and the Florida Keys into the Gulf stock. Common snook occurring north of this line are assigned to the Atlantic stock. The evidence reviewed here suggests the position of this boundary may need to be reevaluated or that the Florida Bay /Keys assemblage may need to be con- sidered separately for management purposes. Future efforts should encompass multiple methods (i.e., genetics, otolith chemistry) and a more detailed spatial analysis of fish from both source areas (east and west coasts) and within Florida Bay to account for the likelihood that both coasts are a source of common snook to parts of Florida Bay. Acknowledgements We thank D. Snodgrass, C. Faunce, J. Whittington and G. Poulakis, E. Robillard and N. Julien for their assistance. The manuscript was improved by the comments of M. Tringali and C. Faunce. This work was supported in part under funding from the Department of the Interior, US Fish and Wildlife Service, Federal Aid for Sportfish Restoration, Project Number F-59. Literature Cited Bath, G.E., S.R. Thorrold, C.M. Jones, S.E. Campana, J.W. McLaren, and J.W.H. Lam 2000. Strontium and barium uptake in aragonite otoliths of marine fish. Geochimica Cosmochimica Acta 64:1705-1714. Campana, S.E. 1999. Chemistry and composition of fish otoliths: pathways, mechanisms and applications. Marine Ecology Progress Series 188:263-297. Campana, S.E., A.J. Eowler, and C.M. Jones 1994. Otolith ele- mental fingerprinting for stock discrimination of Atlantic cod (Gadus morhua) using laser ablation ICPMS. Canadian Journal of Eisheries and Aquatic Science 51:1942-1950. Collins, A.B. and J.H. Einucaine 1987. Ichthyoplankton survey of the estuarine and inshore waters of the Elorida Everglades, May 1971 to February 1972. National Marine Fisheries Service, NOAA Tech. Rep. No. 6. Forrester G.E. and S.E. Swearer 2002. Trace elements in otoliths indicate the use of open-coast versus bay nursery habitats by juvenile California halibut. Marine Ecology Progress Series 241:201-213. Gillanders, B.M. 2002. Temporal and spatial variability in ele- mental composition of otoliths: implications for determining stock identity and connectivity of populations. Canadian Journal of Fisheries and Aquatic Sciences 59:669-679. Gillanders, B.M. and M.J. Kingsford 2000. Elemental finger- prints of otoliths may distinguish estuarine “nursery” habi- tats. Marine Ecology Progress Series 201:273-286. Kimura, M. and T. Maruyama 1971. Pattern of neutral polymor- phism in a geographically structured population. Genetical Research 18:125-131. Ley, J.A., C.C. Mclvor, and C.L. Montague 1999. Fishes in man- grove prop-root habitats of northeast Florida Bay: distinct assemblages across an estuarine gradient. Estuarine, Coastal and Shelf Science 48:701-723. Patterson, H.M., S.R. Thorrold, and J.M. Shenker 1999. Analysis of otolith chemistry in Nassau grouper (Epinephelus stria- tus) from the Bahamas and Belize using solution-based ICP- MS. Coral Reefs 18:171-178. Patterson, H.M., R.S. McBride, and N. Julien. 2004. Population structure of red drum (Sciaenops ocellatus) as deteraiined by otolith chemistry. Marine Biology 144:855-862. Peters, K.M. 1993. Snook early life history. In: R.E. Crabtree, T. M. Bert, and R.G. Taylor, eds. Investigations into nearshore and estuarine gamefish distributions and abun- dance, ecology, life history, and population genetics in Florida. FDNR/FMRI Rep. No. F0165-F0296-88-93-C. U. S. Department of the Interior, p. 1-28. Powell, A.B., D.E. Hoss, W.F. Hettler, D.S. Peters, and S. Wagner 1989. Abundance and distribution of ichthyoplankton in Florida Bay and adjacent waters. Bulletin of Marine Science 44:35-48. Roessler, M. A. 1970. Checklist of fishes in Buttonwood Canal, Everglades National Park, Florida and observations on the seasonal occurrence and life histories of selected species. Bulletin of Marine Science 120:860-893. Roughgarden, J., S. Gaines, and H Possingham 1988. Recruitment dynamics in complex life cycles. Science 241:1460-1466. Rutherford, E.S., T.W. Schmidt, and J.T. Tilmant 1986. The early life history of spotted seatrout, red drum, grey snapper, and snook in Everglades National Park. SFRC-86/07. Everglades National Park, Homestead, EL, USA. Swearer, S.E., J.E. Caselle, D.W. Lea, and R.R. Warner 1999. Larval retention and recruitment in an island population of a coral-reef fish. Nature 402:799-802. Tabb, D.C. and R.B. Manning 1961. A checklist of the flora and fauna of northeast Florida Bay and adjacent brackish waters of the mainland collected during the period July 1957 through September 1960. The Marine Laboratory, University of Miami, Contribution Number 354. Tabb, D.C., D. L. Dubrow, and R. B. Manning 1962. The ecolo- gy of northern Florida Bay and adjacent estuaries. Florida State Board of Conservation, Marine Laboratory Technical Series Number 39. 29 Patterson et al. Taylor, R.G., HJ. Grier and J.A. Whittington 1998. Spawning rhythms of common snook in Florida. Journal of Fish Biology 53:502-520. Taylor, R.G., J.A. Whittington, H. J. Grier, and R.E. Crabtree 2000. Age, growth, maturation, and protandric sex reversal in the common snook, Centropomus undecimalis, from the east and west coasts of South Florida. Fishery Bulletin 98:612-624. Thorrold, S.R., C. Latkoczy, RK. Swart, and C.M. Jones 2001. Natal homing in a marine fish metapopulation. Science 291:297-299. Thorrold, S.R., G.P. Jones, M.E. Hellberg, R.S. Burton, S.E. Swearer, J.E. Neigel, S. G. Morgan, and R.R. Warner 2002. Quantifying larval retention and connectivity in marine pop- ulations with artificial and natural markers. Bulletin of Marine Science 70:291-308. Tilmant, J.T., E.S. Rutherford, and E.B. Thue 1989. Eishery har- vest and population dynamics of the common snook {Centropomus undecimalis) from Florida Bay and adjacent waters. Bulletin of Marine Science 44:523-524. Tringali, M.D. and T.M. Bert 1996. The genetic stock structure of common snook {Centropomus undecimalis). Canadian Journal of Fisheries and Aquatic Science 53:974-984. Tucker, J.W., M.P. Landau, and B.E. Faulkner 1985. Culinary value and composition of wild and captive common snook, Centropomus undecimalis. Florida Scientist 48:196-200. Quinn, G.P. and M.J. Keough 2002. Experimental design and data analysis for biologists. Cambridge University Press, Cambridge, UK, 537p. Wasser, PM. and C. Strobeck 1998. Genetic signatures of inter- population dispersal. Trends in Ecology and Evolution 13:43-44. 30 Gulf and Caribbean Research Volume 17 Issue 1 January 2005 Parasites of the American White Pelican Robin M. Overstreet University of Southern Mississippi, robin.overstreet(®usm.edu Stephen S. Curran University of Southern Mississippi DOI; 10.18785/gcr.l701.04 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Overstreet; R. M. and S. S. Curran. 2005. Parasites of the American White Pelican. Gulf and Caribbean Research 17 (l): 31-48. Retrieved from http ; / / aquila.usm.edu/ gcr/vol 1 7/iss 1 /4 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(Dusm.edu. Gulf and Caribbean Research Vol 17, 31-48, 2005 Manuscript received November 3, 2004; accepted January 7, 2005 PARASITES OF THE AMERICAN WHITE PELICAN Robin M. Overstreet and Stephen S. Curran Department of Coastal Sciences, The University of Southern Mississippi, PO Box 7000, Ocean Springs, Mississippi 39566 USA, E-mail robin.overstreet@usm.edu ABSTRACT Metazoan symbionts, including parasites, infecting the American white pelican (AWP) Pelecanus ery- throrhynchos comprise a list of 75 species, 7 of which are new host records. Several new geographic records are also presented, but generally these have a low value because of the migratory nature of the bird. Evidence suggests that some parasites, mostly flies and other arthropods but also nematodes and digeneans, produce detrimental behavioral or pathologic changes in the AWP. Some of the arthropods transmit microbial agents to the pelican. Two digeneans that have the AWP as a definitive host harm and even kill their catfish intermediate host, especially in aquaculture, and another causes abnormalities and mortality in amphibians. Some of the arthropods with low host- specificity can potentially transmit harmful microbial agents to humans and domestic animals. A few avian blood- flukes, intestinal flukes, and nematodes can potentially cause “swimmers itch,” gastroenteritis, and “anisakiasis,” respectively, in humans. Because of the life cycles of some helminths, presence of those worms can provide an indi- cation as to the dietary items of a specific pelican individual, where the individual has been, and how long it has been present in an area. Feather mites, lice, and diplostomoid digeneans serve as good parasites to indicate phylo- genetic relationships among different pelican species as well as relationships among the Pelecanidae and other fam- ilies such as the Sulidae. Introduction The American white pelican (AWP) Pelecanus ery- throrhynchos serves as a host for numerous parasites, sev- eral of them recently or not previously reported. It serves as an acceptable host for many parasites because it migrates over an extensive, defined, geographic range, all the while feeding on a large variety of prey items. Those prey species in turn serve as intermediate hosts for numer- ous parasites of the AWP, and many of those parasites as well as other symbionts without such complicated life cycles have co-evolved with the pelican. Consequently, knowledge about the symbionts, especially the truly para- sitic fauna, provides knowledge about the dynamics of the bird host during certain seasons, in certain regions, or through time. Further, the AWP nests in groups, allowing for easy transference of certain parasites among flock cohorts. Parasites of birds have been used before by several researchers as indicators of the bird’s biology. For exam- ple, digeneans (Bartoli 1989) have indicated host diets, prey preference, habitat where prey was eaten, and host migration, even though digeneans and other parasites of fishes have been used more often than those of birds as well as used for additional categories of biological indica- tions (e.g., Kabata 1963, Margolis 1963, MacKenzie 1983, Lester 1990, Overstreet 1993, 1997). These articles cite criteria one should meet, which vary considerably, depending on the type of question the biological indicator should answer. Analysis of the phytogeny of bird parasites as well as the co-evolution or host-switching with their hosts also have concerned lice (e.g.. Page et al. 2004) and other parasites. That recent study and others involving other host groups (e.g., Nadler and Hafner 1993) have strengthened our understanding of phylogeny by taking advantage of a variety of molecular approaches rather than performing strictly morphological analyses. Molecular techniques now provide additional useful tools to investi- gate a variety of parasitological problems. This article intends to provide a preliminary foray into many of the AWP’s symbionts. “Symbiont” is a general term used here to encompass organisms that cover a com- plete range of benefit and harm to a “host,” whether com- monly referred to as a “parasite” or not (Overstreet 1978). They include organisms ranging from those with only a loose bond, such as a stable fly, to those “true” parasites like the digenean Bolbophorus damnificus, which is spe- cific to pelicans and exhibits a complicated life cycle in which the intermediate hosts but not the pelican host are harmed. For purposes of this study, we usually refer to each of the symbionts, regardless of the degree of host- specificity, ability to harm a host, or other aspects of its association with the host, as a parasite. Some of these neg- atively influence the bird, pose a potential public health risk, or provide useful biological information about the pelican or its associates. The focus of this article is not meant to emphasize disease in the AWP resulting from par- asites but rather to show how parasites may play an impor- tant role in understanding the biology of the bird. Materials and Methods Data for this article have been gathered from prior col- lections made by the authors, specimens borrowed from museums, and the literature. Collections consist of para- sites from a relatively small number of the AWP. Those 31 Overstreet and Curran birds from the Mississippi-Louisiana region were shot or died during their migration in conjunction with the USDA/ APHIS/ Wildlife Services, provided by the Wildlife Rehabilitation & Nature Preservation Society, or collected from aquaculture facilities. A single specimen was shot at the Summer Lake Wildlife Area, Oregon. We compare our data on the AWP with that collected or described from the brown pelican (Pelecanus occidentalis) in Mississippi or elsewhere. Parasites were removed from birds that were either freshly killed or birds that had been collected earli- er and their alimentary tract frozen or fixed in alcohol or formalin. A few birds were examined thoroughly for para- sites in general, and specific organs of others were exam- ined for certain species of parasites. Parasites were pre- pared using a variety of methods common in our laborato- ry, including some described by Cable (1977), Crites and Overstreet (1991), and Overstreet and Curran (2005). In the most recent collections, we placed representative spec- imens in refrigerated 95% molecular grade ethanol or directly into a -70 °C freezer for molecular studies. Results Appendix 1 lists most of the parasites about which we have knowledge and provides the site in the bird, the geo- graphic location of the infection, and principal references, when applicable. When we considered recorded parasite names to represent junior synonyms, we usually included the accepted names only. We also include in the table infections of parasites that we encountered for this study. The list, plus a single unidentified coccidian protozoan, contains 75 species, 9 of which are flies and 1 a flea with very little specificity toward the AWP but important to the bird’s health. About three of the reports represent syn- onyms or misidentifications of binomial species already on the list. That leaves about 62 listed species, not counting the flies and flea, even though some unidentified species probably represent a complex of species. Of the 62, about 24 have not been reported from the brown pelican (e.g.. Dyer et al. 2002). Many are confined to both pelican species (e.g., Dronen et al. 2003), but others infecting both pelicans also infect other birds. About 10, consisting of lice, mites, and helminths, infect the AWP only. Questionable identifications and an indication of whether infections also occur in the brown pelican are noted in Appendix 1. New geographical records are not individual- ly marked. Appendix 1 also lists seven new records for the AWP based in some cases on careful examination of just a few specimens. These are marked with an asterisk. Even with the inclusion of this study, historically few specimens of the AWP from few localities have been thoroughly examined for parasites. And from these few individuals, often the site of infection has not been recorded. As a result, we predict that many additional parasites infect the AWP. For example, the brown pelican hosts the eimerian coccidian protozoan Eimeria pelecani, but no protozoan other than a record of the coccidian Sarcocystis sp. in cysts in the pectoral muscle (Forrester and Spalding 2003) is known yet from the AWP. Discussion Because some parasite identifications were based on single, few, or incomplete specimens and because some identifications or infections required annotation, we men- tion a few relevant points. For the cestodes, no scolex was found among our tapeworm material of Paradilepis cf. caballeroi, so the species could not be identified, but, based on the diagnosis by Forrester and Spalding (2002), we assume P caballeroi is probably correct. There exists some debate about the status of species in Paradilepis and related genera. Parvitaenia heardi (= Glossocercus carib- aensis by Scholz et al. 2002a) was described from the great blue heron (Ardea herodias) in South Carolina by Schmidt and Courtney (1973), with the brown pelican listed as an accidental host. Rysavy and Macko (1971) reported Parvitaenia eudocimi (= Cyclustera ibisae by Scholz et al. 2002a) from the brown pelican in Cuba as well as from the white ibis {Eudocimus albus), for which it was named. They described P. caballeroi from the double-crested cor- morant {Phalacrocorax auritus). Additional well-fixed material of dilepidids from the AWP should allow exact identifications and perhaps reveal the presence of several additional species. For example, Scholz et al. (2002b) found five different dilepidid species in ''Phalacrocorax olivaceus’’' (= the neotropic cormorant, P. brasilianus) in Mexico. For the digeneans, Bolbophorus confusus has been reported by several authors as one of a few diplosto- moideans infecting the brown pelican and AWP. Overstreet et al. (2002) have shown that at least some of those records represent one and in some cases two related species of Bolbophorus. Whether B. confusus, which we consider to be a European species, exists in North America still has to be determined (Overstreet et al. 2002). One of the two species previously reported in part as B. confusus by at least some authors (e.g., reviews by Olson 1966, Overstreet et al. 2002, Appendix 1) was considered as B. damnificus, and it can be readily acquired by the AWP from feeding on infected channel catfish {Ictalurus punc- tatus) (Overstreet et al. 2002, Overstreet and Curran 2004). The other species is referred to as Bolbophorus sp. of 32 Parasites of White Peeican Overstreet et al. (2002). It has been demonstrated to differ from B. damnificus as shown by sequences of four differ- ent gene fragments by Overstreet et al. (2002) and corrob- orated by Levy et al. (2002) using one fragment. Levy et al. (2002) showed that it infected several fishes but not the catfish. Adults of both of the two species can occur in the same individual pelican host (Overstreet et al. 2002). When we sequenced the ITS 1/2 for three preadult specimens from a single AWP in Oregon, the percentage value for DNA sequence similarity with Bolbophoms sp. of Overstreet et al. (2002) was 99% in contrast with 88% when compared with the same fragment of B. damnificus. The three specimens also had a similarity value of 99%, indicating the immature Oregon specimens were Bolbophoms sp. of Overstreet et al. (2002). Also, based on specimens of diplostomoideans we have seen from north- ern North America, we suspect that the report of Diplostomum spathaceum from the AWP in Manitoba by McLaughlin (1974) probably represents a species of Bolbophoms. He found only three helminths, and only D. spathaceum was a digenean. Since it appears superficially similar to the two species of Bolbophoms that are common in the AWP in Canada, we treat the report as a misidentifi- cation. We found another diplostomoid reported as Bursacetabulus pelecanus in the AWP as well as in the brown pelican. Whether it is conspecific with Bursatintinnabulus macrobursus, which we also found in both local pelican species, is being treated by Charles Blend, Overstreet, and Curran (unpublished data). Several host records for digeneans deserve comment. Ribeiroia ondatrae has been reported from various gulls and the muskrat. McNeil (1949) listed the AWP as a host in Washington, Forrester and Spalding (2002) reported it from Florida, and Dyer et al. (2002) reported it from the brown pelican in Puerto Rico. Originally, Price (1931) did not notice the esophageal diverticula and considered the species in a different genus, but Lumsden and Zischke (1963) confirmed their presence in the type material. The presence of this worm in pelicans is important because of the effect of the species on its amphibian intermediate hosts discussed below. Species of Renicola are difficult to differentiate, primarily because eggs obstruct the view of most of the organs. We appear to have two species. Specimens from Mississippi are similar to Renicola tha- pari, but our relatively young specimens appear different enough from the much larger and more fecund specimens described from the brown pelican in Panama (Caballero 1953) and reported later from that host in Florida and Louisiana by Courtney and Forrester (1974) to consider the identification tentative. A portion of a damaged speci- men collected from Oregon seems to represent a different and possibly new species or one of the few renicolids that infect other white pelican species (e.g., Stunkard 1964). The identification of Prosthogonimus ovatus was based on a single specimen from the wash of the oviduct and a small portion of the cloaca, but it was not initially observed in the cloaca. It has a smaller body, suckers, and eggs than Prosthogonimus folliculus from the American bittern {Botaurus lentiginosus), and, based on reported North American species of the digenean, it seems most consistent with the description of P. ovatus, a species known from several birds, both small and large. Actually, we expect specimens that have been reported from different cosmo- politan hosts as P. ovatus to represent a complex of species. Our measurements of what we identified as Austrobilharzia variglandis are slightly smaller than those reported by Stunkard and Hinchliffe (1952) and may rep- resent an atypical infection. In any event, the eastern mud- snail {Nassarius obsoletus) (also known as the mud whelk, Ilyanassa obsoleta), intermediate snail host for A. variglandis, occurs along the northern Gulf of Mexico as well as along the eastern US seaboard, where infections in it have been investigated (Barber and Caira 1995). Gulls appear to be the primary avian host for the species. Gigantobilarzia huttoni (see Leigh 1957) and Dendritobilharzia pulverulenta (see Forrester and Spalding 2003) infect the AWP in Florida and presumably elsewhere, and other blood flukes infect the brown pelican and other pelicans around the world (e.g., Yamaguti 1971). Nematodes in the genus Contracaecum require a tax- onomic revision. There have been six nominal species reported from the AWP, but, considering a synonym and misidentifications, we considered only four species accept- able; occasionally at least three species occur concurrently in an individual bird. The morphological features of the species do not fit all the descriptions corresponding to the names (e.g., Deardorff and Overstreet 1980). In any event, we have seen three species listed in Appendix 1 as concur- rent in the AWP from Mississippi and Louisiana, with C. multipapillatum being the most common in those locali- ties. As the populations of both the AWP and the brown pelican increase, the juvenile infections in the two local mullets (Mugil cephalus and Mugil curema, common sec- ond intermediate hosts) become more abundant, resulting in pelican infections, which in turn commonly reach over several hundred specimens in an individual bird. In Oregon, we have seen C. microcephalum as identified using the work of BaruTt et al. (1978), and only several specimens occurred in the bird. What we call C. micro- cephalum in North America may be a distinct species but closely related to the European form. Contracaecum 33 Overstreet and Curran microcephalum has been reported throughout the world. Heavy infections by a species reported as C. micro- cephalum from Tanzania were held responsible for pelican mortality there (Nyange et al. 1983). The external features of the clitellate glossiphoniid leech Theromyzon sp. from Oregon differed from those described for T. rude, but the species is clearly in the genus. Six young specimens were restricted to the breast, neck, and head area, and none was associated with the cloaca. Mark Siddall and Elizabeth Borda (American Museum of Natural History) are in the process of sequenc- ing material to establish its identity. No leech has been reported previously from the AWP, but Rothschild and Clay (1957) mentioned that leeches occurred in the vent and gular pouch of pelicans. Feather mites are treated below under pylogenetic relationships. We expect several more feather mites infest the AWP than have been reported. For example, nymphs of three species of hypoderatid mites in the subcutaneous tis- sues of the brown pelican were reported in Fouisiana and Florida by Pence and Courtney (1973), and we have seen unidentified, presently unavailable for study, species in the subcutaneous fat around the trachea of the AWP. Adults of these mites inhabit the nests. Also, the trombiculid Womersia strandtmanni has been reported in the brown pelican by Vercammen-Grandjean and Kobebinova (1968). That chigger caused skin lesions in ducks (Clark and Stotts 1960). Based on knowledge of mite infestations in other pelican species, we suspect related or identical species occur on the AWP. Bird health Depending on what one wishes to consider a cause of disease, there could be several of the organisms listed in Appendix 1 that have a direct or indirect negative influence on the health of the AWP. The fleas, ticks, and flies all can pose a threat to the health of the bird, especially weakened young, captured, or disabled individuals. These have low host-specificity with the pelican; for example, there are eight species of flies listed and presumably many more exist. These arthropods have been observed on young indi- viduals in “nesting areas” in large numbers, and often the birds in question died (Johnson 1976). Whether the young were unhealthy and attracted the flies or whether the flies caused the birds to become unhealthy is uncertain, but, in any event, the flies aided in the demise of many individuals. Johnson (1976) found the adult flies annoying young birds that hatched primarily late in the season in Chase Fake National Wildlife Refuge. The young birds were unable to avoid the flies by moving into open areas, and, once a few flies started feeding on a bird’s flesh in the head or else- where, many more became attracted to feed, and these laid eggs in the bird, resulting in even greater numbers. The flies offer additional means of causing disease. Because they are not specific to the pelican, they often leave one individual or one host species and find another. Even though hippoboscid flies have little ability to fly and infest their hosts primarily through direct contact, most other flies like the blowflies and stable flies travel from host to host. Consequently, those that fly the farthest can more readily pick up a bacterial, viral, or some other infec- tion from one wild or domestic host species and transmit it to another host such as the AWP or even a human. The soft tick Ornithodoros capensis presents another problem. This common argasid has been held responsible for causing the parent birds to desert their nests, sometimes for two years. As indicated above, they are not specific to the AWP, but they infect several different aquatic birds. King et al. (1977a) found that three deserted brown pelican nests in Aransas National Wildlife Refuge, Texas, yielded 2,389 adult and nymphal specimens of the tick. This and perhaps another species {Ornithodoros denmarki) proba- bly caused nest desertion by the brown pelican in Gulf of California nests. Scratching and preening behavior occurred from 32-68% of the morning and afternoon observation times in areas where desertion was greatest (King et al. 1977b). Death of the nestlings may result from transmission of a lethal Soldado-like arbovirus from the tick (Converse et al. 1975). Infestations also are known to reduce brood size in Texas (King et al. 1977a, 1977b). We think the actual importance of this tick to the AWP proba- bly depends on air temperature. Infestations have been reported on the AWP in Texas (King et al. in Duffy 1983), where temperatures remain relatively high. We questioned various biologists such as Robert Johnson and Kory Richardson at Chase Fake National Wildlife Refuge, North Dakota, and Marty St Fouis at the region in and near Summer Fake Wildlife Area, Oregon, and northern California, and they never recalled seeing any ticks on the birds or in their nests from these relatively cool nesting grounds. Perhaps other agents also cause pelicans to desert their nests. Rothschild and Clay (1957) mentioned that entire colonies of pelicans in the southern seas have deserted their nests because of Culex pipiens, referred to as a “house-gnat” rather than a mosquito. The complex of mos- quito species in the C. pipiens-gm\xp has been held respon- sible for extinction or shifting ranges of various bird pop- ulations because it transmitted both bird malaria and avian pox virus (e.g., Warner 1968). We do not include the non- specific mosquitos in Appendix 1. 34 Parasites of White Peeican Lice are much more specific to the pelican than are the flies; in fact some lice species apparently infect no other bird except the AWR They feed on blood and can occur in the thousands on birds that cannot adequately preen them- selves, such as weakened young, captured, and disabled individuals. When someone encounters a pelican with large numbers of lice, the person should assume that the individual bird is in poor health. On one specimen of a brown pelican from Mississippi in September 1993 with a distorted bill, we observed thousands of specimens of lice, primarily of Pectinopygus occidentalis but some of Colpocephalum occidentalis, on its head, back, and wing feathers. The same occurs with the counterparts R tordoffi and C. unciferum on the AWR In fact, we observed feath- er mites associated with the lice on the brown pelican. The “pouch louse,” Piagetiella peralis, is a biting louse that cannot be controlled by normal preening because it occurs in the gular pouch. The healthy AWR usually keeps an infestation in check, but weakened individuals often exhib- it hemorrhagic ulcerative stomatitis and inflammation of the mouth (Wobeser et al. 1974, personal observations). The effect may be serious, and infestations are readily transmitted to young during nesting when infested parents are feeding them. Not all individuals of P. peralis infest the inner surface of the gular pouch, where its large numbers can cover the entire surface along the lower mandible and on the roof of the mouth without producing severe lesions. On 250 examined young birds, Johnson (1976) found them in the pouch of all, and 53 of a subset of 90 had some at the base of the neck, bottom of the feet, and axil of the wings. He noted that such external infestations appeared to subside after the birds reached 2-3 weeks of age. Wobeser et al. (1974) reported a large number of immature lice over the entire body of a dying young juvenile. In the only examined adult from Oregon, we found, in addition to those in the pouch, numerous immature specimens tightly lodged along the shaft of the primary wing feathers and a few younger specimens among the breast feathers. None was associated with pathological alterations. Whether helminth infections harm the AWR depends on factors such as the number of worms present, prior state of the bird’s health, and bird age. Individuals of some members of the anisakid nematode genus Contracaecum often occur in the hundreds in the proventriculus and adja- cent organs of the AWR. Oglesby (1960) estimated over 1,100 individuals from a single AWR that had died in Florida. These were tentatively identified as C. micropapil- latum, a species that Deardorff and Overstreet (1980) found in low numbers concurrent with considerably larger numbers of C. multipapillatum and Contracaecum rudol- phii in other specimens in Mississippi and Louisiana. Adult and fourth stage individuals typically associate with an ulcer where they attach and perhaps feed on the host response tissue. The secretions and excretions by juvenile worms are probably more responsible for local inflamma- tion and necrosis than those by adults (Liu and Edward 1971, Fagerholm et al. 1996). We have seen ulcers both with a well-delimited conspicuous fibrotic protective cap- sule, allowing the nematodes to feed on inflammatory cells without disturbing the adjacent stomach tissue, and with- out such encapsulation. When without the capsule, the lesion is typically associated with extensive inflammation. After the bird host feeds, the nematodes often detach from the ulcer and entwine among the prey material. When indi- viduals of various species of Contracaecum were found present in large numbers, some observers (Owre 1962, Huizinga 1971, Fagerholm et al. 1996) suggested that they help macerate or digest the prey as an initial stage in the host’s digestive process. Contracaecum multipapillatum and related species also have been suggested as being asso- ciated with mortality or poor health of the bird host. Morbidity of hosts of all ages can be suspected when at least some individuals of a relatively large worm burden penetrate through the mucosal layer, when infections have an associated secondary microbial infection, or when an individual is starved (e.g., Oglesby 1960, Owre 1962, Fagerholm et al. 1996). Dyer et al. (2002) also suggested that the same species may have contributed to the emacia- tion and death of brown pelicans in Ruerto Rico. Grimes et al. (1989), who tested the effects of four anthelmintics on Contracaecum spp. and two digenean species in the brown pelican, mentioned unpublished data by Courtney, who demonstrated that nestling pelicans with 95% of the nema- todes removed by treatment showed higher weight gains than untreated controls. Digeneans can also harm the AWR. As with some of the other agents indicated above, the pathological effect often depends on the number of individuals and other fac- tors such as a secondary bacterial infection. Phagicola longus, a small species, probably affects the AWR that nests along the coast because a marine snail and mullets act as intermediate hosts. For example, nestling brown pel- icans 4-5 weeks old from Louisiana contained over 18,000 specimens of P longus along the small intestine and ceca, many in the mucosa and lamina propria. Mesostephanus appendiculatoides, present in lower numbers (e.g., averag- ing 1,112 specimens per bird from the Floridian Gulf of Mexico coast) attached to the villar tips and occasionally penetrated the epithelium (Humphrey et al. 1978, Greve et al. 1987). It was acquired from coastal silversides as well as mullets. Both digeneans, also occurring in the AWR, dis- torted host tissues and produced an inflammatory response 35 Overstreet and Curran but did not kill birds in captivity. As few as 15 specimens of the larger Ribeiroia ondatrae deep in the proventricular mucosa produced necrosis, possibly contributing to mor- tality of the brown pelican (Dyer et al. 2002). According to Rebecca Cole (personal communication, National Wildlife Health Center, Madison, Wisconsin), a heavy infection of Pholeter anterouterus along the intestine of an AWP in Florida killed the bird, possibly in conjunction with an acid fast bacterial infection. The diet of fish allows the potential for harmful effects in addition to helminth infections. Because fish bio-accu- mulate various pesticides and other toxic agents, pelicans and other piscivorous birds can further accumulate such compounds (e.g., Forrester and Spalding 2003). Well-doc- umented cases of the brown pelican with bioaccumulation of high levels of DDT and other pesticides in the late 1950’s and early 1960’s and then other pesticides in 1975 resulted in thin eggs and loss of fledged offspring. The reduced production of young decimated the brown pelican population in the northern Gulf of Mexico and other areas, and a return of successful breeding colonies took several years (Johnsgard 1993). A condition of far less concern involves older individuals feeding on physically dangerous items. Lesions commonly observed by us in the stomach suggest that punctures by spines such as those on pectoral and dorsal fins of catfish and other prey can develop sec- ondary infections and perhaps produce death when the prey is not eaten head-first. Catfish spines killed two adult AWP (Forrester and Spalding 2003); one lacerated the jugular vein and the other perforated the esophagus and stomach. Johnson (1976) observed two young birds, one of which died, with penetrating fish vertebrae lodged in their throat. Related to this kind of damage was a case of poten- tial death resulting when an AWP engulfed a wooden- han- dled ice-pick (Mattis and Deardorff 1988). The bird with the pick had difficulty standing, remained in a squatting position with a contracted neck, could not fly, and could no longer feed or be force-fed. Once the bird was x-rayed and the condition diagnosed, the pick was shown to have entered down the esophagus handle first and perforated that organ, so that the pick could be removed from its lodg- ment and the bird saved only by human intervention. Health of intermediate hosts Not only can the AWP be harmed by a few species of helminth parasites, but a few of the helminths that have lit- tle effect on the pelican can be transmitted by the pelican and have a drastic influence on the intermediate host pop- ulation. Good examples include two diplostomatid dige- neans that infect catfish and a cathaemasiid digenean that infects amphibians. These diplostomatids, Bolbophoms damnificus and Bursacetabulus pelecanus, both can pro- duce mass mortalities of the channel catfish, at least in aquaculture conditions (Overstreet et al. 2002, Overstreet and Curran 2004). The problem with B. damnificus is more confusing than originally presumed by fish farmers and managers because more than one species of Bolbophoms infects the AWP (Overstreet et al. 2002), with a single indi- vidual bird capable of harboring at least two of those species. Only one of these is known to infect the catfish. For the two indicated species that infect the catfish, their eggs are released with the pelican’s feces into the aquacul- ture ponds. The miracidia (infective larvae) of both infect the appropriate snail host, and, after development of at least two asexual stages of the digeneans and ultimate pro- duction of large numbers of infective cercariae, individuals of the cercaria of each species are shed in large pulses available to infect the catfish. Those for B. damnificus enter the fish and finally lodge and encyst, typically in the muscle adjacent to the dermis in the caudal region, and those of B. pelecanus end up unencysted in the vitreous humor of the eye. Infection by B. damnificus also results in pathological alterations in the kidneys (Overstreet and Curran 2004). The snails and up to millions of associated cercariae occur along the shallow sides of fish-ponds where young catfish occur and receive massive infections, often resulting in death (e.g., Terhune et al. 2002). We have exposed catfish to the cercariae of B. damnificus in the lab- oratory and produced death of the fish after periods rang- ing from minutes to days, depending on the dose of cer- cariae (Overstreet et al. 2002, Overstreet and Curran 2004). How many cercariae of B. pelecanus are necessary to harm the catfish was not established, but infections of another diplostome, Austrodiplostomum compactum, which matures in various cormorant species, infected the vitreous humor as well as the brain and spinal cord and also killed the catfish. For it to kill the host necessitated a larger number of the penetrating cercaria than did B. damnificus in short-term laboratory infections. Thousands of very young worms could infect the nerve tissue of the fish (Overstreet and Curran 2004). Consequently, the AWP does not necessarily serve as the only avian source of dige- neans that can cause catfish mortalities and it is not the only scourge of the fish farmers wanting to rid their ponds of pelicans. The AWP and different cormorants eat catfish from the ponds, whether the catfish are infected or not. The example involving harm to amphibians concerns the cathamaesiid digenean Ribeiroia ondatrae. The metacer- caria of this species produced limb malformations in a wide range of amphibians (frogs, toads, newts, and sala- mander) in wild and experimental hosts (Johnson et al. 2002), with survivorship declining significantly with 36 Parasites of White Peeican increasing cercarial exposure (Johnson et al. 2001). Unlike the examples of diplostomids where the pelicans and cat- fish are the only known hosts, R. ondatrae infects a few different vertebrate definitive hosts in addition to pelicans as well as numerous amphibian second intermediate hosts and several snail species of the planorbid genus Planorbella as first intermediate hosts. A similar problem involving harm to the intermediate host concerned recreational fishermen and those interested in the AWP from the late 1920s until many years after in Yellowstone Lake, Wyoming. The pelican colony on Molly Island had to be protected because the birds there transmit- ted the tapeworm Diphyllobothrium cordiceps to the local trouts. When Behle (1958) wrote on the AWP, he indicted that the Park Service officials then felt that the value of the birds offset the loss of available fish. Health of humans and domestic animals As indicated above, some of the flies can transmit microbial infections to pelicans and other hosts, including humans. For example, the blood-feeding stable fly Stomoxys calcitrans, as summarized by Roberts and Janovy (2000), can transmit the flagellates Trypanosoma evansi and members of the Trypanosoma brucei-covapltx, the agents of surra and sleeping sickness in large mam- mals, as well as epidemic relapsing fever, anthrax, brucel- losis, swine erysipelas, equine swamp fever, African horse sickness, and fowl pox. This species also serves as the intermediate host for the nematode Habronema micros- toma in horses. These infections are in addition to the bit- ing that causes severe discomfort in humans and death in livestock. Some of the other flies can also transmit various agents. The possibility of the lice transmitting an agent has not been investigated, but that by pelican-ticks has been studied minimally (Forrester and Spalding 2003). One can say in general that transmission of numerous avian virus- es, many of which are transmitted by arthropods, can have a serious negative influence on domesticated and wild birds and mammals as well as on humans (Perdue and Seal 2000 ). The argasid soft tick Ornithodoros amblus, which acquires short blood meals off the brown pelican and other seabirds in nesting islands off Peru, has been associated with the birds deserting their eggs and young. It possibly transmits infectious agents to the birds. At least two arboviruses, “Huacho” and Salinas,” are transmitted by the tick. Although the effect on the birds was not established, Duffy (1983) reported that humans suffered swelling, itch- ing, occasional gangrene, and even death following multi- ple tick bites. Helminths also can be spread by the AWP to humans. For example, when the bird infected by the schistosome Austrobilharzia variglandis defecates in marine waters containing the eastern mudsnail (Nassarius obsoletus), the snail can get infected by the miracidia (larval stage hatched from the worm’s egg) and this larva undergoes asexual reproduction, ultimately producing many thousands of cer- cariae. The cercaria is the invasive stage shed from the snail that infects the AWP or a variety of gulls and shore birds (e.g.. Barber and Caira 1995). If it invades a human rather than the bird, it does not develop, but rather it estab- lishes a host sensitivity response such that future invasions result in a hypersensitivity reaction in the skin of one who inhabits water containing the cercaria. As the host’s defense responses react against the challenging doses of the cercaria, allergins are released from the cercaria that cause an inflammation. This reaction, called “swimmer’s itch” or “clam digger’s itch,” is painful enough to keep people from entering beaches and other bodies of water that contain infected snails; and, consequently, public swimming areas often are closed, producing a local eco- nomic hardship. Patients are seldom severely harmed, but the hypersensitivity reaction keeps most from revisiting the location. Unlike the two-host schistosome life cycle, most helminths utilize a series of at least two intermediate hosts plus the definitive host. For example (e.g., Huizinga 1967), when a bird with the nematode C. multipapillatum defecates in near shore or freshwater habitats, some cyclopoid and presumably other copepod species feed on the released larval nematode, supporting development to a stage (third stage) or condition (exsheathed second stage) infective to a fish intermediate host. The larva, or more appropriately the “juvenile,” can develop only in certain fish species. When other fish, or in some cases inverte- brates, are eaten by animals other than the AWP or other avian definitive hosts, the worm migrates to the body cav- ity, becomes encapsulated, and remains infective to a peli- can that feeds on the animal. Small fish intermediate hosts can be killed by the worm. Our original research based on non-human animals suggested that if humans ate this fish (e.g., primarily the striped mullet but also the red drum, Sciaenops ocellata, and other fishes), the worm would be digested (Deardorff and Overstreet 1980). However, later research involving RMO (Vidal-Martmez et al. 1994) showed that in some cases, presumably involving a warm period of acclimation, the worm could produce “anisakia- sis.” The term “anisakiasis” defines a disease in warm blooded mammals including humans caused by various ascaridoid species in the family Anisakidae and not just those in the genus Anisakis. Because of the recent increase in brown and white pelican infections following reduced 37 Overstreet and Curran levels of DDT and related compounds, the potential risk is increasing. During that same period of depletion and recovery, the striped mullet in the northern Gulf of Mexico was overfished for the Japanese caviar industry and other needs. The reduced numbers of both avian and fish hosts subsequently reduced infections of C. multipapillatum in mullets, pelicans, and cormorants, but with increases in those hosts, heavy infections are recently beginning to return (unpublished observations). A public health risk also occurs for those eating inad- equately cooked American species of mullet infected with Phagicola longus, a digenean infecting a snail that feeds on eggs shed with host feces by the AWP or a few other birds; the fish becomes infected from the cercaria shed from the snail (Overstreet 1978, Deardorff and Overstreet 1991). Unlike the nematode that infects warm-blooded hosts as a juvenile, P. longus matures in the warm-blooded host, often causing grossly appearing gastroenteritis in herons and raccoon hosts (Overstreet 1978, Richard Heard and Overstreet, personal observations). Indicators of biological activities As described in abbreviated detail above, helminths undergo a complex life cycle involving two or more differ- ent hosts. The AWP is the final, or definitive, host for those listed in Appendix 1. The cycle in different helminth groups differs, and that for each species differs from all others in some ways, usually by the specific hosts involved. Knowledge of these life cycles and life history patterns can provide important biological information on feeding habits and migratory patterns of the host individu- als. For example, Phagicola longus, Mesostephanus appendiculatoides, and Contracaecum multipapillatum all infect the striped mullet, Mugil cephalus, as the second intermediate host. When these parasites are observed in a pelican, one knows that the pelican has been feeding on mullet along the coast. In contrast, B. damnificus and B. pelecanus infect the channel catfish in fresh water, usually far from the coast, and the presence of one or the combina- tion of both in the pelican indicates that it was feeding on the catfish. Of course there exists a variety of other helminths from both habitats, but most do not occur in large numbers. By looking at the relative numbers of these freshwater and coastal parasites as well as the presence or absence of each species, one can get a good indication of where the bird has been and how long ago the bird was feeding on what and in what habitat. Since there is a loss of individuals with time, there is a greater likelihood of a recent infection if there is a heavy infection of a species that can occur in large numbers (e.g., those species indict- ed above). Moreover, this indication of a recent infection can be strengthened when some individuals of certain species possess few or no eggs, indicative of recent acqui- sitions. If specimens of parasites from coastal and inland habitats are both present, evaluation of all these features should provide the necessary feeding and migratory infor- mation. Humphrey et al. (1978) treated the differences in community structure of the above helminths in the brown pelican from the east and west coasts of Florida and from Louisiana. They pointed out the eventual decline in P. longus in adult brown pelicans could result from a possible immune response established during a tissue dwelling stage occurring in the fledgling pelicans. They also specu- lated on the community structure being influenced by a change from mullet as a dietary item when young birds no longer depended on food from their parents. Kinsella et al. (2004), who collected helminths from the AWP in Florida, noted that most of the helminths from their 29 birds had been acquired in the marine habitat, even though many of the birds were collected inland. The community of helminths in the AWP would probably provide a good model to demonstrate an interactive community (Holmes and Price 1986), especially since the parasites have such a diverse array of effects on the bird populations. Even though few birds were examined critically by either Dronen et al. (2003) or us and little can be deter- mined from incomplete data on prevalence or intensity, we can surmise that the endohelminths from the AWPs from the Mississippi-Louisiana region had a greater richness than in the counterparts from the Galveston Bay, Texas, area. Ten endohelminths reported from six AWPs from Texas compared with 19, or at least 20 considering syn- onyms, from Mississippi/Louisiana and with 33 from Florida, where the sample size was much larger (Forrester and Spalding 2002, Kinsella et al. 2004). In all cases, the worms were derived from a combination of freshwater and marine intermediate hosts. In Texas, the brown pelican, a bird that has a more restricted home range than the AWP, had 23 species, a number comparable with those we observed in the AWP but still considerably less than the number of endohelminths that occur in the brown pelican from Florida and presumably Mississippi. We are also interested in knowing what parasites are residents in intermediate hosts in specific habitats. Specific intermediate hosts and cycles for many helminths have not been discovered. The presence of preadult specimens of Bolbophorus sp. of Overstreet et al. 2002 in an AWP on the Summer Lake Wildlife Area, Oregon, suggests that the bird acquired the infection in or near the Area. 38 Parasites of White Peeican Indicators of phylogenetic relationships Different tools have been used to discern phylogenet- ic relationships within and among avian families, includ- ing pelicans. For example, Cracraft (1985) presented a closer morphological relationship, based on an extensive cladistical analysis, between Pelecanidae and Sulidae (gannets and boobies) than between pelecanids and the cormorants or anhingas, once thought to be more closely related to the pelecanids than any other birds. But Warheit et al. (1989), using just the number of ossicles per ring in the sclera of the eye’s corneal hemisphere, separated the pelicans farther from the sulids than the other bird groups. Then, first using DNA-DNA hybridization (e.g., Sibley et al. 1988) and later using DNA sequences of mitochondrial 12S and 16S rRNA genes (1.7 kb) (Hedges and Sibley 1994), the biologists also separated those groups similarly to the arrangement of Warheit et al. (1989). Siegel-Causey (1997) concluded, as did Sibley and colleagues, that the originally designated Pelecaniformes was paraphyletic (having more than one unrelated ancestor), with none of the several studies supporting a monophyletic (single orig- inal ancestor) origin of the order. Only the relationship between the pelicans and shoebills appears consistent with all the molecular data. The author also considered the molecular studies in an elementary stage, with answers requiring a re-examination of traditional morphological characters. Nevertheless, preliminary parasitic data on infections with closely related species of feather mites, diplostome digeneans (species of Bursacetabulus and Bursatintinnabulus), and cyathocotylid digeneans (species of Mesostephanus) seem to support a close relationship of the pelicans with the sulids. Appendix 1 indicates that many of the AWP parasites also occur in or on the brown pelican. There are a few groups of ectoparasites such as feather mites and lice and endoparasites such as diplostome digeneans and tetraboth- riid cestodes that contain counterparts that differ between the two North American pelicans. These and related para- sites allow us a better insight into the phylogenetic rela- tionship between the two pelican species as well as among all pelicans and among the Pelecanidae and other bird groups. Feather mites have been demonstrated to be good par- asitic tools to indicate relationships within and among bird groups (e.g., Mironov 1999). For example, members of the genus Scutomegnina (Avenzoariidae) on the Pelecanidae and Sulidae show a closer relationship among each other than those from birds of either family show to the mites on cormorants and anhingas (Mironov 2000). Moreover, Mironov (personal communication. Zoological Institute, Russian Academy of Sciences, St. Petersburg, Russia) con- siders specific mites from the AWP in general more simi- lar to those on other white pelicans than to those on the local North American brown pelican. For example, Scutomegninia gaudi, originally described from Pelecanus onocrotalus, also occurs on the AWP, but Scutomegninia remipes occurs on all the “subspecies” of the brown peli- can (Mironov 2000), and Megalloptes major occurs on the brown pelican (Mironov and Perez 2000). We expect Megalloptes triphyllurus will be found on the AWP, since it occurs on other white pelican species. Alloptellus pele- canus, already known from Pelecanus onocrotalus, P cris- pus, and P rufescens (see Peterson and Atyeo 1972), prob- ably also occurs on the AWP. We predict a species of Plicatalloptes to be found on the brown pelican that is dif- ferent from P. pelecani. Presumably, several more mite species will be discovered on the AWP. Because of the large number of named and presumably unnamed feather mites showing various degrees of host-specificity in mem- bers of Pelicaniformes, this group of parasites seems the perfect group with which to assess phylogenetic relation- ships among the birds. Since feather lice — like feather mites — are different among brown, white, and other pelicans that have been studied, we predict this group will also provide a powerful insight into the phytogeny of members of the genus Pelecanus. For example, in North American hosts, Colpocephalum unciferum, Pectinopygus tordojfi, and Piagetiella peralis infest the AWP in contrast with Colpocephalum occidentalis, Pectinopygus occidentalis, and Piagetiella busaepelecani, which occur on the brown pelican. Initially (Kellogg 1896), C. unciferum was thought to infest both pelicans, but it was later shown to be different from the material on the brown pelican. Additional related species infest other pelican species and other related species. A cladistical analysis of the species should reflect phylogenetic relationships among all pele- caniforms, including the ancestral association among the different pelicans. Of the Pelecaniformes, pelicans and frigate birds are infested by members of Colpocephalum, but birds in several other orders are also infested (Emerson 1972). Members of Pectinopygus infest some birds in every pelecaniform family except Phaethontidae (trop- icbirds), with several species on pelicans, boobies, and gannets as well as frigate birds, cormorants, and anhingas. Members of Piagetiella infest only pelicans and cor- morants (Price 1970). Members of the diplostomoid digenean genus Bursacetabulus are known from pelicans and a gannet only. Bursacetabulus pelecanus infects the brown pelican (Dronen et al. 1999) and the AWP, and Bursacetabulus morus infects the northern gannet (Moms bassanus). 39 Overstreet and Curran Additionally, two other nominal species in the genus Bursatintinnabulus are reported from the same hosts (Tehrany et al. 1999), although we question the taxonomic status of those latter worms. Six genera of cestodes in the family Tetrabothriidae have shown the genus Tetmbothrius to be pleisiomorphic (^ancestral) (Hoberg 1989, Hoberg et al. 1997). Members of the genus suggest an archaic association of the species among the Pelecaniformes, Procellariiformes, and Sphenisciformes as well as with marine mammals. Evaluating species infecting Phalacrocoracidae seems to illuminate the relationships among the cormorants (Hoberg 1987). Acknowledgments This article is based on an oral presentation in the “American White Pelican Symposium” of Twenty-ninth Annual Meeting of the Pacific Seabird Group at the Santa Barbara Museum of Natural History, Santa Barbara, California, 20-23 February 2002, organized by D.W. Anderson, University of California-Davis, and T. King, USDA/ APHIS. Many people assisted with this study. We thank T. King and D. LeBlanc, USDA/APHIS/ Wildlife Services, Mississippi State, Mississippi, and Port Allen, Louisiana, respectively, along with assistance of B. Dorr and B. Harrel; R. Gaude, Louisiana State University, Louisiana Extension Service; M. St. Louis, R. Klus, and M.J. Hedrick of the Summer Lake Wildlife Area, Oregon Department of Fish and Wildlife; K. Richardson and R. Johnson, previously of the Chase Lake National Wildlife Refuge, North Dakota; and Wildlife Rehabilitation & Nature Preservation Society, Pass Christian, Mississippi, either for pelican specimens or for help obtaining such specimens. We also thank E. Hoberg and P. Pilitt of the US National Parasite Collection, Beltsville, Maryland, R.A. Cole of the National Wildlife Health Center, Madison, Wisconsin, and C. Vaucher and A. de Chambrier of the Museum of Natural History, Geneva, Switzerland, for loaning specimens; S.V. Mironov, Zoological Institute, Russian Academy of Sciences, St. Petersburg, Russia, for identification of feather mites; C. Blend and W. Grater of the Gulf Coast Research Laboratory for sequencing speci- mens of Bolbophorus sp. from Oregon; and R. Palmer, A. Bullard, R. Blaylock, K. Wilkie, M.-M. Bakenhaster, and K. Overstreet for technical assistance. 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Yeh, L.S. 1954. On a new trematode Allechinostomum renale sp. nov. (Trematoda: Echinostomatidae), from Pelecanus ery- throrhynchos . Journal of Helminthology 28:159-164. 43 Partial list of metazoan parasites from the American white pelican. Parasite Site Location^ ID^ Y/N^ Principal references Cestoda (Tapeworms) Cyclustera ibisae intestine FL, TX ID? Y Forrester and Spalding 2003, Dronen et al. 2003, Kinsella et al. 2004 Diphyllobothrium cordiceps intestine WY, MT N Leidy 1872, Woodbury 1932, Scott 1955, Post 1971 (U o m o^ s o (N o o o o (N (N 13 13 t/3 C/3 B S 3 s in o^ -S o ^ § . — ; c/3 ^ o 23 § Vi Q m o o c/3 3 3 c/3 3 o O > o GO Oh o Oh 3 s o Vh Q 3 r^H s £ X X X X X X X Q Q 1 > X < < WY, WY MB Q r 00 U P ^ S Eli X H -V E §■ o ~C3 CQ 2 =2 "2 CQ < hH Q Z &H &H S£ p P o bX) fH P -S P Ph O O P p ^ ■■s O B P o p o p p s p •pj .y o ^ CG 5G ?3 § S P> C3 K bx »C3 Si p bx I Co S P 5 h s -C3 P •S s CG s c /3 Cj s s; .bo P SI Q .bo 6 ~ ~ 1 Co Co ^ O ex C 3 ^ ^ ^ ^ ^ ^ 5g Co s S § g Co s Co S Px P p Q p ■ 2 a p a a Co -2 S 'S q 1 -p eb .§ .§ Q 5 h sa •Sh 4-4 -2 Px Px - 2 a -s 1 •2 es eb C) p a "St c:) q bx q q q q * q APPENDIX 1 (continued) Parasite Site Location^ ID^ Y/N^ Principal references Digenea (Flukes) (continued) Renicola sp. kidneys OR N Present study o o o o (N (N "S 13 c/3 a W) a a3 in 13 c/3 C S cn o o (N bX) 03 Oh 00 0^ 03 Oh 00 c/3 O g ^ g ^ P -P :3 0^0 P-H 2 J ^ J ^ oo" 3 §) 'B xi (D p. > o o iv tp tp Q o- o- -p p p p Ph o' 00 o p > O -p § o o p p Q p p> Ss o c/3 r-H _P ^ OJO g OX) P c/3 -1 Vh P > o -p p p p S c/3 p > o ffi m ON >4-H P V, § ^ P P ^ Q m S o § (N O OX) o "2 T3 c3 P ^ p. Q 00 p § § 2:; p 3 to NO ^ NO P P ^ g 3 (N Ph NO NO ON P o p Oh P TO P P p J! m o o (N P P P P o m o o (N OX) p p Ph 00 -P P P OX) O p p p ^ Q Pop ^ ^ £ o- Q o- Q p p SP ^ I S p o o- < J X tP H < Q < oo" 00 oo" tp XI oo" tp tp ^ X O H p p p P P P C/T C^ c/3 C^ c/3 p P 3 c/3 P OX) 3 c/3 P OX) 3 3 C/3 P OX) 3 c/T p c/T p p 'Cl p 'C p 'C p 'C _p p P p p p p p p p p *p *p p -p p op p p -p p c/3 P c/3 P > Ph > Ph > > Ph > o O o o O o o o u c/3 u c/3 Oh Oh c/3 Oh Ph P Ph p Ph Ph P Ph X H p p P OX) p X Ph O o -p p p o a: J3 P -P o t2 "p gn ^ goo X s J3 •&H s g s p S g P CO •S? "s p u s ■3 I I p s p CO s g ?3 NJ NJ S NJ CO S g t NJ P s St Ph Ph S St stomach Cyathostoma phenisci trachea, lung MS Y Present study O) 0 a ’■3 a o o HH Q a> u S3 c2 Si IS '3 a 'u f<^ 5 ? S ^ _0 s s o .S a ^ Oo c?" ? I ^ I ^ H§ K ^ cj CH3 C -o o O o CO o -O Oh >3 Oh OJ C/3 £ ^ !3 O p: Cu Co S I S O o o o CO o o K C) Oi ^ ^ E^ ^ E? § ^ K NO IT) ON -O OX) OX) o ffi no" ON 00 ^ r^ NO O (U ^ o .a ’5=^ Oh F3; ^ ON ON 0^ > 03 O NO IT) ON 03 O IT) ON ON O £ B £ I ^ u £ OO ON ^ 00 ^ ON Oj- C3N NO ^ IT) ON o c/3 03 a o CIh J .Sh ro -== ^ OX) O OX) o P K ? 03 o 03 O »3 < ta cd GO O 1— H GO U o o o a m < H" X' o < < _3 u hJ a) U H _3 FL FL FL FL FL OR Q GO KS u PQ 03 GO GO 3a Q GO 3 FL GO Q GO 3a GO go" s 3 3 3 3 o 3 3 3 3 43 ’h 3 3 c/3 C/3 5^ 3 -HH i3 3 > O 3 > O d 3 > O Oh C/3 3 d 3 > O ^H 3 X 3 ^H 3 X 3 ^H 3 X 3 ^H Oh ^H Oh ^H Oh 3 ^H Oh C-M ^3 icm ^3 icm 03 O 03 a CO c/3 <3 J3 <3 o o Oh O OX) ■a g -' ;§. OX) a ^ ^ 2 3 S 43 u CO ?3 - a ^ Oh C) cO 43 Oh £ } o s I •S tS £ Oh Siphonaptera (Fleas) Ceratophyllus niger body and nest BC Y Holland 1985 APPENDIX 1 (continued) Parasite Site Location^ ID^ Y/N^ Principal references Hippoboscidae (Louse Flies) Icosta albipennis body USA Maa 1969 (listed as probably accidental, pelican species not identified) Olfersia sorida body USA? ? Maa 1969 X X X X X X X o^ co^ co^ 03 03 (O 03 1-H p p p P P p P o o o o o o o c/3 c/3 c/3 c/3 c/3 c/3 c/3 P p P P P P P X -p 40 40 40 40 40 o o o o o o o i— 5 i— 5 i— ) i— 5 i— 5 i— ) i— 5 Q Q Q Q Q 00 o^ 3 Q OX) 3 X H CO ’cO B ^ o ■S' « 3 a C/!} (D S .6 (U O t/3 (D CIh X o- Q 00 (N o o _o to 0 _ § o 1 s 1 1 ^ 1-2 CO CO ^ c a O o cn TO o cO > o ^ TO CO OX) a cO o. 00 od a > o o o i-H 0) o 2 § § £ X o p o • iij CO cO TO T3 CO CO p p a a U U a TO p P hJ u EIh 0^ 0^ 0^ 0^ TO TO TO TO o o o o X) X) X) X) 0^ 0^ 0^ TO OO TO o o o 3 I a CO 'p 'in £ P ^ § & a < I ^ ^ ^ TO ^ 1 I O u CO 4) dominat- ed all transects, comprising more than 75% of the samples (Table 1). The phi values decreased in each transect of other sampled bays. In UBA, and mainly in UBM bay, a predominance of fine and very fine sand, associated with silt+clay was observed (Table 1), except at transect I in UBM (phi = 1.5). The organic matter content in the sub- stratum was lowest in the offshore region (transect I and II) of the 3 bays, whereas I was the highest in the other tran- sects (Figure 2). There was a clear water temperature difference among transects during spring and summer. Water temperature at transects I through III was lower than at transects IV through VI (Figure 3). During other seasons, the mean 50 Ecology of Rock Shrimp in Brazil TABLE 1 The mean diameter of the sediment (phi), quantity of mud (% silt+clay) and mean number of Sicyonia dorsalis by trawl (n) at each transect at each bay sampled during 1998 and 1999. Transects Bays phi (0) Mar Virado % mud n phi (0) Ubatuba % mud n phi (0) Ubatumirim % mud n I 4.3 46.8 4.2 3.2 16.0 0.3 1.5 2.6 0.1 II 5.7 75.3 3.5 3.99 21.2 0.8 3.8 23.9 0.6 III 6.2 88.3 6.7 5.3 61.9 00 bo 4.4 35.7 17.3 IV 5.9 81.2 1.5 5.7 76.3 15.7 4.9 49.6 1.4 V 5.8 79.7 6.0 4.8 47.3 3.9 4.0 22.2 7.6 VI 5.4 64.4 11.7 3.6 36.8 9.0 4.4 33.4 5.2 Total 5.6 6.4 5.4 water temperature values were homogeneous. Variation in the mean bottom salinity within each bay is shown in Figure 4. Differences in salinities between bays is substan- tial with the lowest mean values recorded in MV. In gener- al, higher salinity ranges were found at transect I, whereas lower salinities were found at transects IV and VI (Figure 4). A total of 2,498 shrimps was obtained, 1,385 during the first year, and 1,113 during the second year. The analy- sis of shrimp distribution reveals they are contagiously dis- tributed in the studied area (P < 0.01). For the pooled sam- ple, the absolute abundance was highest in UBA (922), fol- lowed by MV (804) and UBM (772). The comparison of shrimp abundance among bays, years, transects and sea- sons is shown in Table 2. No significant difference in abun- dance was found between years or among bays {P < 0.05; Table 2). ■ MV 12- HUBA ^ 10 - I II III IV V VI Transects Figure 2. Mean values (±sd) of organic matter content in sed- iments (%) at each sampled transect in bays studied. MV = Mar Virado, UBA = Ubatuba, UBM = Ubatumirim. Sicyonia dorsalis was more abundant along transects VI in MV bay and IV in UBA Bay than along other tran- sects. In UBM, catches were highest along transect III. In general, the lowest number of specimens were collected along transects I and II, at each bay (Figure 5). Significant differences were obtained among transcripts (P < 0.05, Table 2). The highest shrimp abundance occurred during spring (October to December) 1998 and early summer (January and February) and the early summer and late spring (November and December) 1999. These periods had sig- nificantly higher shrimp than other seasons (P < 0.05, Table 3). Conversely, lowest abundances occurred during fall and winter. There was a good fit between S. dorsalis and 5 envi- ronmental variables, and this relationship is explained by Abundance = 11.78 - 1.67 (bottom temperature) - 4.63 (bottom salinity) - 0.03 (% organic matter) - 0.13 (depth) + 0.97 (phi) (r = 0.30, P= 1.0001 E-^, n = 432). Water temperature and salinity were negatively associated and mud content (phi) was positively associated with the num- ber of individuals. However, no correlation was observed between organic matter content and depth in the distribu- tion of this species (P > 0.05, Table 4). The analysis indi- cated that more individuals were collected in conditions of higher percentage of silt and clay, bottom temperature between 19 and 22 °C and salinity between 30 and 34 psu) (Table 1, Figure 6). Also, there greater numbers of S. dor- salis in depths < 15m in spring and summer (Figure 7), fol- lowing a decrease in bottom water temperature (Figure 3). In fall and winter, there was more homogeneity in the spa- tial distribution of S. dorsalis, however the abundance was lower than other seasons. 51 Bottom temperature (°C) Bottom temperature (°C) Costa et al. Summer Transects Winter Transects Figure 3. Boxplots showing mean, standard deviation, season in 1998 and 1999. Autumn Transects and minimum temperature values (°C) for each transect and MV UBA UBM Transects within bay Figure 4. Boxplots showing mean, standard deviation, maximum and minimum salinity values (psu) for each transect within each bay in 1998 and 1999. MV = Mar Virado, UBA = Ubatuba, UBM = Ubatumirim. 52 Ecology of Rock Shrimp in Brazil TABLE 2 Results of the analysis of variance of the mean catch (data logjQ-transformed) of Sicyonia dorsalis by year, bay, transect or season. Source df MS F P Bay 2 2.21 2.47 0.0855 Transect (bay) 15 6.42 7.20 0.0001 Year 1 1.24 1.38 0.2403 Season 3 37.71 42.27 0.0001 Season x Year 3 9.23 10.34 0.0001 Discussion Castro-Filho et al. (1987) showed that the study region is strongly influenced by 2 types of water currents: coastal waters (CW) and tropical waters (TW). These currents occur during fall and winter, causing an increase in water temperature and salinity to over 21 °C and 35 psu, respec- tively. Also, another current occurs throughout late spring and summer, the South Atlantic Central Water (SACW), causing decreases in water temperature (< 20 °C) and bot- tom salinity (< 35). The incursion of the TW into the upper- most water layers and the dislocation of the CW towards the ocean during the fall and winter cause vertical mixing and thus eliminate the existing seasonal thermocline, caus- ing the SACW to recede towards the offshore region. The intrusion of SACW was detected in this study during spring and summer at 10 and 15 m isobaths. Our results indicate that fluctuations in the seasonal and bathy- metric distribution of S. dorsalis were influenced by varia- tion in water temperature caused by these currents. When intruding into the bays, SACW causes a decrease in water temperature and confinement of the shrimp in shallower areas (< 15m). Similar results were also reported for the shrimp Xiphopenaeus kroyeri (Heller, 1862) by Nakagaki and Negreiros-Fransozo (1998), Rimapenaeus constrictus (Stimpson, 1874) by Costa and Fransozo (2004), and the “argentinean” shrimp Pleoticus muelleri Bate, 1888 by Costa et al. (2004), all in Ubatuba bay. In contrast, during late summer and autumn, when bottom- water temperature increased, a few specimens were captured in shallower areas. It may be inferred that the elevation of water temper- ature during these periods caused the migration of shrimp to the outer areas of the bays In spite of the association found between the abun- dance of S. dorsalis and low salinity conditions, there is no evidence of a direct influence of salinity in the distribution of this species. Past biological studies on S. dorsalis were restricted to bathymetric distribution, and occurrences on sediment type (Williams 1984, Sanchez and Soto 1985, DTncao 1995). Only Gunter (1950) and Fransozo et al. (2002) have focused on the influence of salinity and stated that S. dorsalis were captured in areas where salinity was > 33.5 psu. However, Gunter (1950) found only 10 indi- viduals 8.05 km offshore in the Gulf of Mexico in Texas, and Fransozo et al. (2002) found 35 individuals in Fortaleza bay, Ubatuba, Sao Paulo. According to our results and the bathymetric distribution mentioned for this species, we suggest that it prefers areas with values above 30 psu. Perez Farfante (1985) also pointed out that other congeneric species such as S. brevirostris Stimpson 1871 and S. ingentis (Burkenroad, 1938) occur in waters of high salinity (33 to 35 psu) and that these shrimps do not depend upon estuarine waters for their life cycle. Transects Figure 5. Mean number of shrimp by bay and transect during 1998 and 1999. MV = Mar Virado, UBA = Ubatuba, UBM = Ubatumirim. 53 Costa et al. TABLE 3 Monthly catch of Sicyonia dorsalis with each bay in 1998, 1999, and total catch for each season. Results of the ANOVA are shown for each season. Abundance followed by the same letter in the column (Season) do not differ statistically (P > 0.05). MV = Mar Virado; UBA = Ubatuba; UBM = Ubatumirim. Month Year MV 98 99 Bays UBA 98 99 UBM 98 99 Total 98 99 Season Total January 1 112 20 61 8 35 29 208 Summer/98 = 58 a February 9 64 10 80 2 28 21 172 Summer/99 = 394 b March 3 8 5 3 0 3 8 14 April 1 0 2 2 2 32 5 34 Fall/98 = 38 a May 2 4 1 4 5 2 8 10 Fall/99 = 45 a June 2 0 11 0 12 1 25 1 July 8 4 21 6 25 3 54 13 Winter/98 = 251 b August 44 4 34 26 23 1 101 31 Winter/99 = 66 a September 32 4 34 12 30 6 96 22 October 40 19 44 31 21 7 105 57 Spring/98 = 1038 c November 85 50 31 26 81 98 197 174 Spring/99 = 608 be December 240 68 296 162 200 147 736 377 Total 467 337 509 413 409 363 1385 1113 2498 The abundance of S. dorsalis in the bays does not dif- fer statistically, although it was higher in UBA bay, fol- lowed by MV bay. This probably results from the higher content of silt and clay in those areas. The more sorted sed- iments in the other sites, as for transect III in UBM and transect VI in UBA, are apparently preferred by this species, and appear to favor establishment of populations. Similar results were obtained by Sanchez and Soto (1987) for a population of S. dorsalis in the Gulf of Mexico and Perez Farfante (1985) for the geminate species, S. disdor- salis (Burkenroad, 1934), in the eastern Pacific where shrimps were found associated with muddy sediments. In transects where the number of shrimps was highest, besides the prevalence of silt + clay, we observed that these sites are located in a more sheltered area of each bay. Because of the particular hydrodynamics acting on these areas, water currents are weak at transects VI in MV bay, TABLE 4 Results of a multiple linear regression among environ- mental factors and the number of Sicyonia dorsalis. Environmental factors t P bottom temperature (°C) -2.951 0.0033 bottom salinity (psu) -2.918 0.0037 depth (m) -0.808 0.4200 organic matter -0.338 0.7360 phi (f) 3.585 0.0004 at transects III and V in BM and transects III, VI, and mainly IV, in UBA bay. This favors the deposition of fine sediments, and consequently allowing settlement of S. dor- salis. 10 -, — ^ — I — ^ — I — ^ — I — ^ — I — 16 - 19 19-22 22-25 25-28 28-31 Temperature (°C) Figure 6. Plot of the mean number of shrimp in each salinity and water temperature class per trawl. 54 Ecology of Rock Shrimp in Brazil Figure 7. Distribution of the mean (±sd) number of shrimp by depth class per trawl by season (S = summer, A = autumn, W = winter, P = spring). The spatial distribution of many penaeidean shrimps is mainly influenced by texture and organic content of the substratum (Dali et al. 1990). However, the organic matter content of sediments does not seem to affect the distribu- tion of S. dorsalis for this area. The data obtained in the present study has confirmed the influence of texture of the sediment, therefore the distinct features of the sediment in each bay contributes in a significant way to the occurrence of the shrimps along the studied region. The distribution of the penaeids species Metapenaeus macleayi (Hasweell, 1879), Penaeus monodon Fabricius, 1798, Penaeus escu- lentus Haswell, 1879, P. semisulcatus De Haan, 1884 and R. constrictus are more influenced by grain size than by the availability of food (Ruello 1973, Brandford 1981, Somers 1987, Costa and Fransozo 2004). Although water temperature and sediment type offer a most convincing explanation for distributional patterns of S. dorsalis, it is important to realize that other factors such as diurnal and nocturnal variation, competition and predation may also influence its distribution. Acknowledgments We are grateful to the Fundagao de Amparo a Pesquisa do Estado de Sao Paulo for providing financial support (#94/4878-8, #97/12108-6, #97/12106-3, #97/12107/0 and #98/3134-6). We are also thankful to the NEBECC co- workers for their help during field work, to Dr. E. Trinca (Biostatistics Department, Biosciences Institute, UNESP) for her statistical support, and to E.A.M. Ereire for his assistance with the map illustration. All collections in this study were conducted in compliance with current applica- ble state and federal laws. Literature Cited Bauer, R.T. 1992. Repetitive copulation and variable success of insemination in the marine shrimp Sicyonia dorsalis (Decapoda, Penaeoidea). Journal of Crustacean Biology 12:153-160. Bauer, R.T. 1996a. Role of the petasma and appendices masculi- nae during copulation and insemination in the penaeoid shrimp Sicyonia dorsalis (Crustacea: Decapoda: Dendrobranchiata). Invertebrate Reproduction and Development 29:173-184. Bauer, R.T. 1996b. A test of hypotheses on male mating systems and female molting in decapod shrimp using Sicyonia dor- salis (Decapoda: Penaeoidea). Journal of Crustacean Biology 16:429-436. Branford, J.R. 1981. Sediment and the morphometric equation for Penaeus monodon and Penaeus indicus from of the Red Sea. Estuarine, Coastal and Shelf Science 13:473-476. Castro-Filho, B.M., L.B. Miranda, and S.Y. Myao. 1987. Condigoes hidrograficas na plataforma continental ao largo de Ubatuba: variagoes sazonais e em media escala. Boletim do Instituto Oceanografico 35:135-151. Costa, R.C. 2002. Biologia e distribuigao ecologica das especies de camaroes Dendrobranchiata (Crustacea: Decapoda) na regiao de Ubatuba (SP). Doctoral Thesis, Instituto de Biociencias, UNESP, Botucatu, Sao Paulo, Brazil, 178 p. Costa, R.C. and A. Fransozo. 2004. Abundance and ecologic dis- tribution of the shrimp Rimapenaeus constrictus (Crustacea: Penaeidae) in the northern coast of Sao Paulo State, Brazil. Journal of Natural History 38:901-912. Costa, R.C., A. Fransozo and A.P Pinheiro. 2004. Ecologic dis- tribution of the shrimp Pleoticus muelleri (Decapoda: Penaeoidae) in the Southeastern Brazil. Hydrobiologia 529:195-203. Costa, R.C., A. Fransozo, F.L.M. Mantelatto, and R.H. Castro. 2000. Occurrences of shrimps (Natantia: Penaeidea and Caridea) in Ubatuba bay, Ubatuba, Sao Paulo, Brazil. Proceedings of the Biological Society of Washington 113:776-781. 55 Costa et al. Costa, R.C., A. Fransozo, G.A.S. Melo, and F.A.M. Freire. 2003. An illustrated key for Dendrobranchiata shrimps from the northern coast of Sao Paulo state, Brazil. Biota Neotropica 3:12p. [Available at http://www.biotaneotropica.org.br/ v3nl]. Dali, W., B.J. Hill, PC. Rothlisberg, and D.J. Staples. 1990. Behavioural responses to the environment. In: Blaxter, J. H. S. and A.J. Southward, eds. The biology of the Penaeidae, Vol. 27 Advances in Marine Biology. Academic Press, San Diego, CA, USA, p. 333-355. DTncao, F. 1995. Brazilian rock shrimps of the genus Sicyonia (Decapoda: Sicyoniidae). Nauplius 3:101-125. Fransozo, A., R.C. Costa, F.L.M. Mantelatto, M.A.A. Pinheiro, and S. Santos. 2002. Composition and abundance shrimp species (Penaeidea and Caridea) in Fortaleza bay, Ubatuba, Sao Paulo, Brazil. In: Modern Approaches to the Study of Crustacea, (ed. Escobar Briones and F. Alvarez. Kluwer Academic Press, Mexico, p. 117-123. Gunter, G. 1950. Seasonal population changes and distributions as related to salinity, of certain invertebrates of the Texas Coast, including the commercial shrimp. Contributions in Marine Science 1:1-52. Hakanson, L. and M. Jansson. 1983. Principles of lake sedimen- tology. Springer- Verlag, Germany, 315 p. Nakagaki, J.M. and M.L. Negreiros-Fransozo. 1998. Population biology of Xiphopenaeus kroyeri (Heller, 1862) (Decapoda: Penaeidae) from Ubatuba bay, Sao Paulo, Brazil. Journal of Shellfish Research 17:931-935. Negreiros-Fransozo, M.L., A.L.D. Reigada, and J.M. Nakagaki. 1999. Diel varitations in decapod catch rate and size of cap- tured individuals in a subtropical area of Brazil. In: J.C. Von Vaupel Klein and F.R. Schram, eds. The Biodiversity Crisis and Crustacea, A. A. Balkema, Rotterdam, Brookfield, The Netherlands, p. 643-656. Perez Farfante, I. 1985. The rock shrimp genus Sicyonia (Crustacea: Decapoda: Penaeoidea) in the eastern Pacific. Fishery Bulletin, US 83:1-79. Perez Farfante, I. and B. Kensley. 1997. Penaeoid and sergestoid shrimps and prawns of the world. Keys and diagnoses for the families and genera. Editions du Museum national d’Histoire naturalle, Paris, Prance, 233p. Ruello, N.V. 1973. The influence of rainfall on the distribution and abundance of the school prawn Metapenaeus macleayi in the Hunter river region (Australia). Marine Biology 23:221-228. Sanchez, A.J. and L. A. Soto. 1987. Camarones de la superfamil- ia penaeoidea (Rafinesque, 1815) distribuidos en la platafor- ma continental de suroeste del Golfo. 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Biostatistical analysis. 4th ed. Prentice Hall, UK, 663 p. 56 Gulf and Caribbean Research Volume 17 Issue 1 January 2005 Distribution of Myodocopid Ostracods in Tampa Bay Florida^ and Association with Abiotic Variables Stephen A. Grabe Environmental Protection Commission of Hillsborough County, Florida DOI; 10.18785/gcr.l701.06 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Grabe, S. A. 2005. Distribution of Myodocopid Ostracods in Tampa Bay, Florida, and Association with Abiotic Variables. Gulf and Caribbean Research 17 (l); 57-68. Retrieved from http://aquila.usm.edu/gcr/voll7/issl/ 6 This Article is brought to you for free and open access by The Aquila Digital Community It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf and Caribbean Research Vol 17, 57-68, 2005 Manuscript received September 13, 2004; accepted January 21, 2005 DISTRIBUTION OF MYODOCOPID OSTRACODS IN TAMPA BAY, FLORIDA, AND ASSOCIATION WITH ABIOTIC VARIABLES Stephen A. Grabe Environmental Protection Commission of Hillsborough County, 1900 9th Avenue, Tampa, Florida 33605 USA. Present address: Janicki Environmental, Inc., 1155 Eden Isle Dr, NE, St. Petersburg, Florida 33704 USA, Phone 727-895-7722, E-mail SGrabe@JanickiEnvironmental.com AfiST/MCr My odocopid ostracods were identified from > 600 benthic samples collected from Tampa Bay, Florida, during 1995 to 2001, as part of an annual synoptic survey of the benthos. At least 24 taxa were present. Parasterope pollex was the most abundant (76%) and most frequently collected (48%) species; Rutiderma darbyi (28%) and Eusarsiella disparalis (16%) were the next most frequently collected species. Logistic regression and “center of abundance” calculations were used to identify habitat “preferences” for the most frequently occurring species. With the exception of P. pollex, these were more likely to occur in coarser sediments, in more saline waters, and at greater depths than the mean for Tampa Bay. Parasterope pollex occurred over the widest ranges of salinity and sediment types, although it preferred medium to fine sand-sized sediments; P. pollex was also the species most tolerant of low dissolved oxygen concentrations. Introduction Materials and Methods Myodocopid ostracods are common inhabitants of estuarine and marine sediments, although species-specific quantitative ecological information is often lacking. The different families of myodocopids appear to serve different roles in energy transfer. Filter feeding is believed to be typ- ical of the Cylindroleberidae, detritivory of the Philomedidae; the Cypridinidae include scavengers, and both the Sarsiellidae and Rutidermatidae appear to be predators (Cannon 1933, Kornicker 1975, Vannier et al. 1998). Many species are capable of migrating into the water column (Schram 1986, Alldredge and King 1985), where they may serve as prey for zooplankton (Vannier et al. 1998) and fish (Hobson and Chess 1976). At least 34 species of myodocopid ostracods have been identified as occurring in shallow, near-shore waters of peninsular Florida, including the Gulf of Mexico (GOM) (Kornicker 1977, 1983, 1984a, 1984b, 1986a, 1986b, Kornicker and Iliffe 1989, Horsley 1990, Grabe et al. 1995, Kornicker and Grabe 2000). With the exception of work done in southwest Florida (Grabe et al. 1995), these papers primarily address the taxonomy of myo- docopids. Ecological information on myodocopids is often ancillary to the species descriptions. This study examines the spatial distribution and taxo- nomic composition of myodocopid ostracods in Tampa Bay, Florida, one of the largest estuaries in Florida (> 1,000 km^ ; Clark and Macauley 1989). Habitat prefer- ences are quantified for the more frequently occurring species. Representative specimens from these collections are deposited in the US National Museum. The study employed a stratified (by 7 bay segments) probabilistic design (Larsen et al. 1994; Coastal Environmental, Inc. 1994). Hexagonal grids were random- ly superimposed over the Tampa Bay estuarine system. Within each hexagon, the sampling location was randomly determined, with a known probability of inclusion. Bay segments included Boea Ciega Bay, Hillsborough Bay, Lower Tampa Bay, the Manatee River, Middle Tampa Bay, Old Tampa Bay, and Terra Ceia Bay (Figure 1). Although the program commeneed in 1993 and continues to the present, ostracods were analyzed only from 610 samples collected during 1995 to 2001 (Figure 1). All sampling occurred during late July-early October. Benthic infauna, hydrographic profiles, and sediments were collected using the standard EMAP techniques adopted by USEPA for the Louisianan Provinee (Holland 1990). At eaeh station, the water column profile for tem- perature (°C), dissolved oxygen (DO; mg/1), and salinity (psu) was measured with a Hydrolab Surveyor 3. Sediment samples were eollected with a 0.04 m^ Young sampler. A core was removed from each sample and stored, on ice, for subsequent characterization of the sedi- ment. Benthie samples were stored, on ice, after adding a solution of magnesium sulfate to relax the organisms. Samples were later sieved (0.5 mm mesh) and then fixed in a 10% solution of borax-buffered formalin and Rose Bengal. Ostracods were not a taxon of interest to the bay- wide benthie monitoring program. However, the myodocopid ostracods were removed from most of the samples collect- ed during 1995 to 2001 and identified to the lowest practi- cal taxonomic level. 57 Grabe Figure 1. Location of sampling stations for myodocopid ostracods in Tampa Bay, Florida, 1995-2001. Bay segments are BCB (Boca Ciega Bay), HB (Hillsborough Bay), LTB (Lower Tampa Bay), MR (Manatee River), MTB (Middle Tampa Bay), OTB (Old Tampa Bay), and TCB (Terra Ceia Bay). Subareas are AR (Alafia River), HR (Hillsborough River), LMR (Little Manatee River), MCB (McKay Bay), and PR (Palm River). 58 Distribution of Myodocopid Ostracods in Tampa Bay TABLE 1 Mean, median, and range of selected abiotic variables by relative depth, from Tampa Bay, Florida 1995-2001. Variable Mean Median Range Depth (m) 2.8 2.5 0.1-13.2 Silt+Clay (%) 8.4 4.4 0.1-91.8 Temperature-Surface (°C) 28.9 29.0 21.6-39.2 Temperature-Bottom (°C) 28.7 28.7 21.6-39.2 Salinity-Surface (psu) 25.2 26.1 2.4-35.9 Salinity-Bottom (psu) 26.1 26.9 4.3-36.0 Dissolved Oxygen-Surface (mg/1) 6.2 6.1 1.1-13.2 Dissolved Oxygen-Bottom (mg/1) 5.2 5.4 0.2-14.0 Sediments were analyzed to determine the pereentage of silt+clay (%SC) particles < 63 pm diameter. An aliquot of sediment was wet sieved through a 63 pm mesh sieve and dried to a constant weight (Strobel et al. 1995). Data collected by Long et al. (1994) from Tampa Bay were used to estimate a relationship between %SC and mean grain (cj)) using TableCurve 2D (SYSTAT 2002): %SC = 1/(0.0097 + 1.575 (adjusted = 0.947) (j) was then estimated for each %SC value from the 1993- 2001 samples. Sediments were then categorized (e.g., medium sand, mud) according to the Wentworth scale breakpoints for (j) (cf. Percival and Lindsay 1997). The percent similarity of species associations were examined using the Sorensen coefficient for presence- absence (Clarke and Warwick 2001). Logistic regression was used to characterize habitat preferences for the 10 most frequently occurring species (cf. Huisman et al. 1993, Peeters and Gardiniers 1998, Ysebaert et al. 2002). Forward stepwise multiple logistic regression (SPSS, Inc. 2000) was used to identify abiotic variables best able to predict the occurrence of the 10 species. Logjg {n+ 1) transformed abiotic variables used in this analysis include depth (m), salinity, temperature, DO, and %SC (arc sine (ASN)). TableCurve 2D (SYSTAT 2002) was used to develop univariate Gaussian logistic regression equations so that the “optimum” value and the “tolerance” (preferred range) could be calculated (Peeters and Gardiniers 1998). McFaddens’s Rho^ was used as a measure of goodness-of- fit (McFadden 1974, Hensher and Johnson, 1981). Values are similar to, but generally lower than, the coefficient of determination. Hensher and Johnson (1981) suggest that values between 0.2 and 0.4 represent a good fit. Results of these analyses should be treated cautiously as the sample sizes are small relative to those used by Peeters and Gardiniers (1998) and Ysebaert et al. (2002). Center of abundance calculations were also made: S(species abundance abiotic variable)/!! species abun- dance. Results and Discussion Study area Sample depths during the study ranged from 0.1 to 13.2 m, although the median depth was 2.5 m (Table 1). Near-bottom salinities in Tampa Bay during the summer- fall period are typically in the polyhaline (18-30 psu) range (Table 1). Sediment types in Tampa Bay included coarse sands (including shell hash; <1.7 %SC), medium sands ( 1.7 < 4.51 %SC), fine sands ( 4.51< 11.35 %SC), very-fine sands (> 11.35 < 25.95 %SC), and mud- sized sediments (> 25.95 %SC). Tampa Bay sediments are predominantly medium to fine sand-sized sediment, although mud-sized sediments are located in tributaries and portions of Hillsborough Bay (Figure 2). Near-bottom DO concentrations in the bay are generally above 4 mg/1, although mesohaline and polyhaline very fine sand and mud habitats were often hypoxic. Overview of the mydocopid assemblage At least 20 species of myodocopids have been identi- fied to date from Tampa Bay. The 2 most abundant and fre- quently occurring species were Parasterope pollex and Rutiderma darby i (Table 2). Most taxa occurred in < 1% of the samples and represented < 0.1% of the individuals col- lected. The Sorensen coefficient showed that P. pollex and Eusarsiella disparalis were most similar in their co-occur- rence (coefficient = 36), followed by E. texana- Asteropterygion oculitristis (32) and E. texana-P pollex (31). 59 Grabe MCB ' ‘ ■ PR Figure 2. Map depicting the distribution of sediment types in Tampa Bay, Florida. Site codes are found in Figure 1 legend. Selected taxa Cylindroleberidae. Amboleberis americana has been reported in the Atlantic Ocean from North Carolina to Brazil as well as in the Caribbean and the COM; it has also been reported from the Pacific coast of central America (Kornicker 1986b). In Tampa Bay, this species was most often found from the central bay to the GOM, generally proximal to the main shipping channel (Figure 3). Logistic regression showed that the probability of occurrence increased with salinity and depth and decreased as %SC increased (Table 3). This species preferred the greatest depths of the 10 species (Table 4). It was also collected over the narrowest range of salinities (Table 4). The optimal sed- iment type appeared to be coarse sand (%SC < 1.7). A sin- gle ovigerous specimen was found with 21 eggs (Table 5); Horsley (1990) reported a maximum of 37 eggs. Asteropterygion oculitristis has been found off coastal Georgia (Darby 1965) and is reported to range to Texas in 60 Distribution of Myodocopid Ostracods in Tampa Bay TABLE 2 Taxonomic inventory, frequency of occurrence (%FO), percent composition (%COMP), and mean numbers m ^ (standard error (s^), ±1) of myodocopid ostracods collected from Tampa Bay, Florida, 1995-2001 {n = 610). % FO % COMP Mean (s^, ±1) # m“^ Cylindroleberidae Amboleberis americana (Muller 1890) 4.1 0.1 2.2 (0.6) Asteropella sp. 0.2 <0.1 <0.1 <0.1) Asteropella maclaughlinae Kornicker 1981 1.0 <0.1 <0.3 (0.1) Asteropterygion oculitristis (Darby 1965) 12.1 0.3 6.0 (0.9) Parasterope pollex Kornicker 1967 48.2 76.4 1,621.0 (230.2) Prionotoleberis salmoni Kornicker 1986 0.5 <0.1 0.2 (0.1) Philomedidae Harbansus paucichelatus (Kornicker 1958) 4.6 0.2 3.9 (1.3) Pseudophilomedes ambon Kornicker 1984 0.2 <0.1 <0.1 (<0.1) Pseudophilomedes darbyi Kornicker 1989 6.2 0.2 4.5 (1.0) Rutidermatidae Rutiderma darbyi Kornicker 1983 28.4 19.8 420.1 (50.3) Rutiderma mollitum Darby 1965 1.8 0.6 12.2 (6.6) Sarsiellidae Eusarsiella sp. 1.8 <0.1 0.7 (0.3) Eusarsiella childi Kornicker 1986 8.4 0.7 15.7 (6.8) Eusarsiella cresseyi Kornicker 1986 1.6 <0.1 0.5 (0.2) Eusarsiella disparalis (Darby 1965) 15.7 0.6 12.2 (2.5) Eusarsiella elofsoni Kornicker 1986 0.5 <0.1 0.1 (0.1) Eusarsiella ozotothrix (Kornicker and Bowen 1976) 0.3 <0.1 0.2 (0.2) Eusarsiella radiicosta (Darby 1965) 0.8 <0.1 0.5 (0.3) Eusarsiella spinosa (Kornicker and Wise 1962) 3.4 0.1 1.3 (0.3) Eusarsiella tampa Kornicker and Grabe 2000 2.0 0.1 1.4 (0.5) Eusarsiella texana (Kornicker and Wise 1962) 11.8 0.8 17.4 (7.7) Eusarsiella zostericola (Cushman 1906) 1.5 <0.1 1.0 (0.5) Family /genera undetermined Mean density (Total myodocopid ostracods) 0.8 <0.1 0.2 (0.1) 2,121.9 (235.6) the GOM (Kornicker 1986b). In Tampa Bay it was prima- rily found in Middle and Lower Tampa bays (Figure 3). Logistic regression showed that probability of occurrence increased with depth and DO and decreased as %SC increased (Table 3). The optimum habitat appeared to be salinities > 25 psu and sediments of coarse to fine sands (< 8 %SC) (Table 4). In coastal SW Florida, A. oculitristis abundance was positively associated with %SC (where %SC ranged up to about 25%) and was negatively associ- ated with the sorting coefficient (Grabe et al. 1995). Brood sizes ranged from 11 to 18 (Table 5). Parasterope pollex has been reported from bays and estuaries from Nova Scotia, Canada, south to the Chesapeake Bay and along the Gulf coast of Florida to depths of about 13 m (Kornicker 1986b, Grabe et al. 1995). Parasterope pollex was the most widespread myodocopid in Tampa Bay (Figure 3) and it was the only species com- monly collected in the upper portions of the bay. Bay- wide, P. pollex was collected in almost half of the samples, and it was present in 69% of the Old Tampa Bay samples. Densities ranged to 67,350 m“^ in Hillsborough Bay and averaged > 3,000 m~^ in Old Tampa Bay, 2,500 in Hillsborough Bay and 1,600 bay-wide. This frequen- cy of occurrence and the mean densities are lower than those reported by Hulings (1969) for a bay in Massachusetts. Parasterope pollex was found in 90% of his samples from Hadley Harbor (near Martha’s Vineyard), and seasonal means for adults ranged from 2,360-,440 This species was collected in Tampa Bay over the widest ranges of salinity and %SC (Table 3). Grabe et al. (1995) found that P. pollex abundance in SW Florida was 61 Grabe Figure 3. Distribution of A) Amboleberis americana^ B) Asteropterygion oculitristis, and C) Parasterope pollex in Tampa Bay, Florida, 1995-2001. associated with fine sand-sized sediments; in this study the optimal sediments were the medium to fine sand-sized sed- iments that predominate in Tampa Bay (Table 4). Parasterope pollex was also the species most tolerant of low DO concentrations (Table 4). Logistic regression showed that depth, DO and %SC were the most important variables explaining the occurrence of P. pollex (Table 3). Brood sizes ranged from 4-12 (Table 5). Horsley (1990) summarized data from several studies and estimated that the maximum number of eggs for the largest (1.44 mm CL) female would only be seven. Philomedidae. Harbansus paucichelatus is reported to occur from North Carolina into the COM and to Belize in the Caribbean Sea (Kornicker 1984a). In Tampa Bay, H. paucichelatus was found in the middle to lower portions of the bay, including Terra Ceia Bay (Figure 4). Logistic regression showed that salinity and %SC were key vari- ables affecting its occurrence (Table 3). This species pre- ferred coarse to fine sand-sized sediments and polyhaline salinities (Table 4). Horsley (1990) collected this species most often from medium and fine sand-sized sediments. Brood sizes ranged from 3-6 (Table 5). Pseudophilomedes darbyi has been reported from North Carolina south into the GOM as far west as Texas (Kornicker and Iliffe 1989). In Tampa Bay, P. darbyi was found mainly in Middle and Lower Tampa Bay but did penetrate into Old Tampa Bay (Figure 4). Logistic regres- sion showed this species’ presence to be positively associ- ated with salinity and depth and negatively associated with %SC (Table 3). Pseudophilomedes darbyi preferred the second deepest waters of the 10 species; it prefers the nar- rowest range of salinities and coarse to medium sands (Table 4). Brood sizes ranged from 3-7 with a median of 4 (Table 5). Rutidermatidae. Rutiderma darbyi occurs from North Carolina to south Florida and the Bahamas and into the GOM (Kornicker 1983). It was widespread throughout Middle and Lower Tampa Bay and penetrated midway into both Old Tampa Bay and southern Hillsborough Bay (Figure 4). Logistic regression showed an association with depth, salinity and %SC (Table 3). Although a Gaussian response curve could not be fitted for %SC, the probabili- ty of occurrence was 0.7 at 0 %SC (coarse sands) and approached 0 at 15 %SC (very fine sands). Horsley (1990) found R. darbyi to be more common in medium and fine sands. Brood sizes were small and ranged from 2-6 eggs (Table 5). Kornicker (1986b) reported that the Rutidermatidae generally brood 3-4 eggs regardless of size. Sarsiellidae. Eusarsiella childi was described by Kornicker (1986a) from specimens collected in SW Florida and has been reported from the GOM at depths to 12.8 m. Although E. childi was most frequently found in the lower bay, it did penetrate into Old Tampa Bay and Hillsborough Bay; there was also a single occurrence in upper Boca Ciega Bay (Figure 5). Logistic regression showed that %SC and salinity were the key abiotic vari- ables (Table 3). Eusarsiella childi appeared to inhabit the narrowest range of sediment types, preferring coarse sands (Table 4). This contrasts with observations off Marco 62 Distribution of Myodocopid Ostracods in Tampa Bay TABLE 3 Summary of forward stepwise logistic regression analyses for the association between selected abiotic variables and the 10 most frequently occurring myodocopid ostracod species. McFadden’s LlO LlO LlO LlO Rho^ Constant Temperature Salinity Depth DO ASN%SC Cylindroleberidae Amboleberis americana Coefficient 0.23 -25.4 NS 14.8 2.9 NS -31.6 Odds Ratio >2 X 10 ^ 19 0 Asteropterygion oculitristis Coefficient 0.11 -5.9 NS NS 2.8 3.4 -7.1 Odds Ratio 16 27 <1 Parasterope pollex Coefficient 0.02 - 1.0 NS NS NS 1.4 -1.4 Odds Ratio 4 <1 Philomedidae Harbansus paucichelatus Coefficient 0.12 -15.2 NS 9.2 NS NS -28.0 Odds Ratio 9,793 0 Pseudophilomedes darbyi Coefficient 0.24 -7.5 NS 4.3 -3.1 NS -25.7 Odds Ratio 1,039 21 0 Rutidermatidae Rutiderma darbyi Coefficient 0.24 -7.5 NS 4.3 3.1 NS -25.7 Odds Ratio 1,039 21 0 Sarsiellidae Eusarsiella childi Coefficient 0.16 -11.5 NS 7.4 NS NS -39.3 Odds Ratio 1,643 0 Eusarsiella disparalis Coefficient 0.02 -1.3 NS NS NS NS -5.2 Odds Ratio < 0.1 Eusarsiella spinosa Coefficient 0.09 34.3 -26.6 NS 2.4 NS NS Odds Ratio Eusarsiella texana 0.04 0 10 Coefficient 3.8 - 8.2 3.1 NS 2.1 NS Odds Ratio 0 22 8 Island in SW Florida where E. childi abundance was posi- tively associated with %SC (where % SC ranged up to about 25%) (Grabe et al. 1995). Eusarsiella childi also tended to occur at shallower depths than many of the other species. Brood sizes ranged from 3-14 (Table 5). Horsley (1990) reported a range of 1-10 eggs in 5 specimens. Eusarsiella disparalis was described from coastal Georgia (Darby 1965) and ranges from North Carolina to just north of Tampa Bay (Kornicker 1986a). Eusarsiella disparalis is widespread in Tampa Bay, ranging from the mouth of the bay to the mouths of the Hillsborough and Alalia rivers in Hillsborough Bay (Figure 5). Logistic regression showed that %SC was the most important abi- otic variable affecting its presence or absence in Tampa Bay (Table 3). A preferred salinity regime could not be defined using logistic regression. Eusarsiella disparalis was collected over the second widest salinity range after P. pollex, and was the species that most often co-occurred 63 Summary of habitat characteristics for the 10 most frequently occurring myodocopid ostracods in Tampa Bay, Florida, 1995-2001. COA = center of abun- dance (R = range); OPT = optimum (TOL = tolerance). NR = Gaussian logistic regression equation could not resolve either an “optimum” or a “tolerance” range. in in a\ NO q p q in c^ 1 NO 1 cn On 1 p NO 1 o NO 1 00 1 ON 1 cn 1 (N ON 1 in 00 ON X 00 q f'p q ON q ON q ON oo q ON 1 cn 3 1 'St 3 (N 3 in 'St in in 3 'St m 3 1—1 in NO 3 3 in O m 3 p d 00 3 p d o m 3 --H (N in in in 'St NO (N in p in p in NO q NO CO B in in in P NO P in q in NO in q in q NO X O H X O H X O H X O H X o H X O H X O H X o H X o H X o H < H < H < H < H < H < H < H < H < H < H O O Oh O Oh O Oh O Oh O Oh O Oh O Oh O Oh O Oh O Oh Q U o U O U o u o U o U o u o U o u o u o in NO q o o o (N a\ (N q q q CO in (N 1 o o o\ in p 1— H NO in 00 (N ON in q in 00 'St q in NO 'St 1 m o ON 1 00 ON NO (N 1 1 'St 1 o 1 1 5S 1 in 1 H 1 o 1 ■sst" H t-H H H H 1— ^ o c4 O in o O o (N o q O p O p d o d q ON (N cn p NO p ON p 00 p (N r-H (N q ON p CO 3 'St cn (N rn in q ri q (N 'St (N X H R X R X R X R X R R X R X R O H X R &H < H < H < H < H < H < H < H < H < H < H O Ph O Oh o Oh O Oh O Oh O Oh O Oh o Oh o OLh o Oh Q U O U o u O u o U o U o U O u o u o u o CO rvi q q q o p q q 1— H ON q in q 'St NO 1— H q q q CO q 00 CO q 1— H 1 o p 1 CO NO 1 q (N 1 p ON 'St 'Sl" NO d CO (N q d d ON 1 p t-H d 00 3 d 1— H d 3 00 d 1 q CO 1 (N d 1 (N CO d o o q d d q d q d d o t—H q d o d q q q r-H CO q q CO q CO p q d q in q d q in (N d 'St d 'St d CO d CO d (N d (N d in d 'St d 'St d X O H o H O H X o H X O H X o H X O H X R R O H < H < H < H < H < H < H < H < H < H < H o Oh O Oh o Oh o Oh O Oh o Oh O Oh O Oh O Oh O Oh u o U o u O U o U o u o U o U o U o U o 'Sj- q q q p P NO CO q 'St CO ON q q ON q q CO CO q" 'St 'St CO q p in CO p CO CO NO in CO (N CXj in in 'St CO in 'St CO (N CO 'sJ- CO NO CO CO 1 ON in CO 1 q d (N 1 oo NO (N CO d T— H 1 (N d 1 q (N w CO 1 'St w 1 q CO 1 00 d w 00 / V in d q ^ ^ d ' — ^ oo q d ON d d O CO d q 00 t-H q 00 (N d P 1— H t/) s w p d CO q d CO q CO (N w o ON (N q (N CO CO ON (N 'St q q CO (N 00 00 in ON oo d d in 00 NO H (N d (N d (N d (N d (N d (N d (N d (N d (N d (N d hH g X R X R X O H X o H X o H X o H X o H X o H X o H X R d < H < H < H < H < H < H < H < H < H < H O Oh O Oh O Oh o Oh o OLh o Oh o Oh O Oh o Oh o Oh u o u o U o u o u o u o u O U O u o u o •a s ^ SI I ^ u s C) K •S I C) :§ s rs ^ -o s s ■s' I ^ 25% (the maximum reported in the study, Grabe et al. 1995). Brood sizes ranged from 2-13 (Table 5) whereas Horsley (1990) reported a maximum brood of 8 eggs. TABLE 5 Mean and range of brood sizes of myodocopid ostra- cods from Tampa Bay, Florida {n = number of speci- mens). Species (n) Mean Range Cylindroleberidae Amboleberis americana (1) 21 NA Asteropterygion oculitristis (4) 15 11-18 Parasterope pollex (30) 8 4-12 Philomedidae Harbansus paucichelatus (15) 4 2-6 Pseudophilomedes darbyi (7) 5 3-10 Rutidermatidae Rutiderma darbyi (55) 3 2-6 Rutiderma mollitum (3) 3 2-4 Sarsiellidae Eusarsiella childi (45) 8 3-14 Eusarsiella cresseyi (7) 5 4-7 Eusarsiella disparalis (26) 7 4-11 Eusarsiella spinosa (4) 5 2-7 Eusarsiella tampa (5) 6 4-8 Eusarsiella texana (25) 6 2-12 65 Grabe Figure 5. Distribution of A) Eusarsiella childi^ B) E. disparalis, C) E. spinosa, and D) E. texana in Tampa Bay, Florida, 66 Distribution of Myodocopid Ostracods in Tampa Bay Conclusions At least 20 species of myodocopid ostracods were identified from > 600 samples collected from Tampa Bay during 1995-2001. Numerical dominants included P. pollex and R. darbyi, and the most frequently occurring species included P. pollex, R. darbyi, and E. disparalis. Of the 10 most frequently occurring species, most were more likely to occur in coarser sediments, in more saline waters, and at greater depths than the mean for Tampa Bay. Given that many were described from coastal waters, the abiotic preferences reported here suggest that most of these ostra- cods penetrate the bay from the GOM. Whether there is a seasonal effect on the distribution is unknown since only wet season samples have been analyzed. However, bay salinities are noticeably higher during the dry season (Lewis and Estevez 1988), and ostracods may be more widespread when salinities are higher. Additionally, the observation that species such as A. americana tend to be found near the main shipping channel suggests that enhanced influx of Gulf waters via the shipping channels (Lewis and Estevez 1988) could facilitate immigration of neritic species. In contrast, P pollex is a typical “bay species,” less frequently collected in the lower reaches of the bay. Accordingly, P. pollex shows greater affinity for lower salinities, finer-grained sediments, and lower DO than the species presumed to originate in the GOM. Acknowledgements This project was supported by both the Environmental Protection Commission of Hillsborough County (EPCHC) and the Tampa Bay Estuary Program. Appreciation is extended to L. Kornicker for identifying/verifying the identifications of some of these ostracods and for review- ing the draft manuscript. 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Potter, R.P. Thomas, J.M. Lazorchak, G.B. Collins and R.L. Graves, eds. 1995. Environmental monitoring and assessment program (EMAP). Laboratory methods manual — Estuaries. Vol. 1: Biological and physical analyses. EPA, Office of Research and Development, Narragansett, RI, USA. EPA/620/R-95/008. United States Environmental Protection Agency. Office of Research and Development. Narragansett, RI, USA. SYSTAT 2002. Table Curve 2D ver. 5.01. Richmond, CA, USA. Vannier, J., K. Abe, and K. Ikuta. 1998. Peeding in myodocopid ostracods: Punctional morphology and laboratory observa- tions from videos. Marine Biology 132:391-408. Ysebaert, T., P. Meire, P.M.J. Herman, and H. Verbeek 2002. Macrobenthic species response surfaces along estuarine gra- dients: Prediction by logistic regression. Marine Ecology Progress Series 225:79-95. 68 Gulf and Caribbean Research Volume 17 Issue 1 January 2005 Manatee Occurrence in the Northern Gulf of Mexico^ West of Florida D. Fertl Geo-Marine, Inc. AJ. Schiro Texas A6’M University, Galveston G.T. Regan Marterra Foundation, Inc. C.A. Beck U. S. Geological Survey N. Adimey U.S. Fish and Wildlife Service et al. DOI: 10.18785/gcr.l701.07 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Fertl, D., A. Schiro, G. Regan, C. Beck, N. Adimey, L. Price-May, A. Amos, G. Worthy and R. Crossland. 2005. Manatee Occurrence in the Northern Gulf of Mexico, West of Florida. Gulf and Caribbean Research 17 (l): 69-94. Retrieved from http://aquila.usm.edu/gcr/voll7/issl/7 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf and Caribbean Research Vol 17, 69-94, 2005 Manuscript received August 31, 2004; accepted January 31, 2005 MANATEE OCCURRENCE IN THE NORTHERN GULF OF MEXICO, WEST OF FLORIDA D. Fertl^, A.J. Schiro^, G.T. Regan^, C.A. Beck^, N. Adimey^, L. Price-May^, A. Amos^, G.A.J. Worthy^, and R. Crossland^ ^Geo-Marine, Inc., 550 East 15th Street, Plano, Texas 75074 USA ^Marine Mammal Research Program, Texas A&M University at Galveston, 4700 Avenue U, Building 303, Galveston, Texas 77551. Current address: 206 Fourth Street S.W., Ruskin, Florida 33570 USA ^Marterra Foundation Inc., PO. Box 646, Gulf Shores, Alabama 36547 USA ‘^US Geological Survey, Florida Integrated Science Center, Sirenia Project, 412 NE 16th Avenue, Room 250, Gainesville, Florida 32601 USA ^US Fish and Wildlife Service, Jacksonville Field Office, 6620 Southpoint Drive, South #310, Jacksonville, Florida 32216-0958 USA ^Center for Coastal Studies, Texas A&M University at Corpus Christi, 6300 Ocean Drive, Corpus Christi, Texas 78412 USA ^University of Texas Marine Science Institute, 750 Channelview Drive, Port Aransas, Texas 78373 USA ^Physiological Ecology and Bioenergetics Lab, Department of Biology, University of Central Florida, 4000 Central Florida Boulevard, Orlando, Florida 32816-2368, USA ABSTRACT Reports of West Indian manatees (Trichechus manatus) in the US Gulf of Mexico west of Florida have increased during the last decade. We reviewed all available manatee sighting, capture, and carcass records {n = 377) from Alabama, Louisiana, Mississippi, and Texas since the early 1900s; only 40 of these were previously published. Manatees were reported most often in estuarine habitats, usually either near a freshwater source or natural or indus- trial warm-water springs/runoffs during winter months. The recent increase in manatee records may be due to a combination of increased public awareness and dispersal of manatees, most likely seasonal migrants from Florida. We caution that the presence of artificial warm-water sources outside of the manatee’s traditional range may attract an increasing number of manatees and could increase the incidence of cold-related mortality in this region. Introduction The West Indian manatee {Trichechus manatus) oceurs patchily along coastal areas throughout the Gulf of Mexico (GOM) and Caribbean Sea, the southeastern United States, and the northern and eastern waters of South America (Lefebvre et al. 2001). Historically, manatees were found along the entire GOM Coast from the Suwannee River in Florida to the Bay of Campeche, Mexico, and considered common in south Texas (Gunter 1941, Powell and Rathbun 1984, Lefebvre et al. 2001). Records of manatee sightings, carcasses, and captures west of Florida are limited, but have increased in recent years. Materials and Methods All available historical and current (up to August 2004) sighting, carcass, and capture records (excluding archeological data) of manatees in the northern GOM, west of Florida were compiled for this report. Our goal was to provide a comprehensive document that included records collected from numerous widely scattered resources. Powell and Rathbun (1984) and Rathbun et al. (1990) provided the most recent reviews of manatee records in this area. Resources used to provide new data included marine mammal stranding networks in each state west of Florida, current literature, as well as files of the Sirenia Project (US Geological Survey), Fish and Wildlife Research Institute (Florida Fish and Wildlife Conservation Commission [FWC]), and the US Fish and Wildlife Service [USFWS]. Since the occurrence data were com- piled from a variety of sources, the precision and accuracy of the data also varied. We corrected any errors noted in published accounts. When only geographic descriptions were given, we determined coordinates as near as possible to the physical description. The locations with geographic coordinates were not assumed to be correct and were veri- fied. If coordinates did not fit the description, the record was verified for accuracy and then moved as close to the original geographic description as possible. The October 2001 sighting of a manatee 144.8 km south of Mobile Bay in open water was excluded from Appendix I and any tab- ulations, since it was not attributable to any state waters. This sighting is included in the map, and information is presented in the discussion. Manatees are physically and behaviorally distinctive from all other marine mammals. 69 Fertl et al. Therefore, species identification by the general public could usually be confirmed with a general description. Confirming multiple sightings of the same manatee or dif- ferent animals is problematic, and unless a manatee has distinguishing marks (e.g., propeller scars), it is impossible to identify single individuals (Beck and Reid 1995). Results We compiled 377 records from US waters west of Florida; these were 339 sightings, 30 carcasses, and 8 cap- tures. Sighting and carcass records are presented in Appendices I and II, while captures are presented in the state summaries. Forty of the 377 records were previously published. Louisiana {n = 147) and Alabama (n = 132) accounted for the majority of the occurrence records (39% and 35%, respectively). All sighting, carcass, and capture records are plotted in Figure 1 along with major waterways and intermittent wetland habitat which serve as possible transit pathways for manatees. Alabama Alabama’s records consisted of 128 sightings, 4 car- casses, and no captures (Appendices I, II, Figure 1). Two of these records were previously published. The years with the most records were 1995 (20 sightings), 2000 (23 sight- ings and 1 carcass), and 2002 (22 sightings and 1 carcass). June had the most information in = 29). Sighting size var- ied from 1 to 1 1 manatees; single individuals were most frequent. Cow/calf pairs (including multiple parrs) made up 14 sightings (Appendix I). An occurrence record noted by Caldwell and Caldwell (1973) near Gulf Shores was excluded since the type (sighting or carcass) was not noted. The Alabama Marine Mammal Stranding Network (AMMSN) received reports of a lone manatee on 13, 16, and 25 December 1991. On 13 January 1992, an adult male manatee was found dead on the east shore of Mobile Bay (Appendix II, AMMSN number SHCM 119). There was no immediate, obvious indication as to the cause of its death; however, the animal had large and round fecal obstructions in the intestine consistent with possible expo- sure to cold. In fact, water temperature in the bay recorded two weeks earlier was 1 1 °C. This assessment is consistent with description of cold stress syndrome described by Buergelt et al. (1984) and Bossart et al. (2003). Due to the proximity in sighting dates with the actual carcass recov- ery, this was likely the same individual sighted during December 1991 (Appendix I). On 26 February 2002, a 260 cm dead male manatee was found in Mobile County, on the south shore of Dog River (Appendix II, AMMSN SHCM 350). A field necrop- sy revealed that the entire intestinal tract was black inside, and the large intestine contained solidified masses resem- bling charcoal briquettes. The cause of death was cold stress, again consistent with the descriptions provided in Buergelt et al. (1984) and Bossart et al. (2003). On 11 September 2003, 11 manatees were sighted in McReynolds Lake at the Mobile-Tensaw River Delta. Two of the 11 were matched to manatees known from the Crystal River population in northwest Florida; both were males, one known since 1982, and the other since 1987 (Sirenia Project files). Mississippi Mississippi’s records consisted of 27 sightings, 3 car- casses, and two captures (Appendices I, II, Figure 1). Ten of these were previously published. The greatest number of sightings was recorded in 1979 (5 sightings and one cap- ture) and 2001 (4 sightings and 1 carcass). February (n = 7) and August (n = 6) had the most records. Single individ- uals were most frequently sighted. Two of the three com- piled carcass records indicated that the animals died from starvation and/or cold stress. Powell and Rathbun (1984) reported one carcass and 24 manatee sightings in Mississippi between 1978 and 1981; 16 of these sightings occurred near Biloxi Bay between 28 November 1979 and 19 January 1980, but no further details were provided. A 1.8 m individual was caught in a trawl and released alive on 3 December 1981 in Graveline Bayou (30.33333, -88.66666) (Gunter and Perry 1983, Powell and Rathbun 1984). One male mana- tee, “Beauregard,” was rescued by Sea World of Florida in January 1979 at Gulfport Harbor (30.35000, -89.16667) and relocated to Florida. He was rehabilitated in captivity and released in February 1985. Using a satellite tag, Sirenia Project biologists tracked him upon release (Gunter and Corcoran 1981, Powell and Rathbun 1984, Rathbun et al. 1990). “Beauregard” was tracked from the Homosassa River to the Suwannee River in Florida (Rathbun et al. 1990). Powell and Rathbun (1984) noted that Gunter & Corcoran (1981) erroneously reported the capture date to be 7 January 1979. Louisiana Louisiana’s records consisted of 131 sightings, 15 car- casses, and one capture (Appendices I, II, Figure 1). Eight of these were previously published. The years with the most records were 1995 (23 sightings and 3 carcasses) and 2002 (24 sightings and 2 carcasses). Eighty-nine percent (n = 130) of the 147 records provided seasonal informa- tion; June and July had the most records with 21 and 31, 70 Manatee Occurrence in the Northern Gule oe Mexico T" S9* Pensacola Bay Carcass Sighting Capture Major Waterway Intermittent Wetland Habitat Mautfcal Miles Gulf of Mexico Figure 1. Distribution of manatee records (« = 378) from 1853-2004 in the northern Gulf of Mexico, west of Florida. Maps are separated, east and west of the Mississippi River delta, for visual clarity and resolution. Major waterways and intermittent wet- land habitats (shaded areas lacking resolution to depict small waterways) are depicted; these demonstrate potential pathways of manatee movement. 71 Fertl et al. respectively. Single individuals were most frequently sighted, though occasional sightings of cow/calf pairs were made (Appendix I). On 22 July 1995, a single manatee was sighted about 4.8 km southeast of Breton Sound Marina in a canal near Hopedale, Louisiana. This individual was later uninten- tionally hit and killed by an oil well crew boat (> 25 m in length) (Appendix II). The carcass (LA9501) was collect- ed by the Louisiana Department of Wildlife and Fisheries, photographed, buried, and later recovered by the Louisiana Marine Mammal Stranding Network. Photographs were subsequently matched to an animal previously pho- tographed in Tampa Bay, Florida, in February 1995 (Anonymous 1996). Another individual was seen repeatedly for several weeks in November 1995 in the 21 °C warm- water efflu- ent of the Michoud Power Plant (Appendix I). On 31 January 1996, following a sharp drop in air temperature, a dead manatee was observed floating out of a waste-water discharge pipe on the south shore of the lake (Appendix II); this was probably the same animal sighted in November. The necropsy revealed that the animal had been feeding up to the time of death. The cause of death was determined to be entrapment in the discharge pipe and subsequent drowning (J. Valade, personal communication, US Fish and Wildlife Service, 6620 Southpoint Drive South, Suite 310, Jacksonville, FL 32216-0958). A manatee photographed on 10 August 1999 in Bayou Lacombe was later matched to a carcass (no assigned spec- imen number) recovered in Bayou Patout on 14 December 1999 (Appendix II). Assuming travel along the complex coastline of Louisiana, this is a distance of about 417 km, and included crossing the mouth of the Mississippi River delta. It is possible that this individual made its way through the intricate bayou system of Louisiana, though this is speculative. On 8 September 1999, a 3.3 m individual was caught in a trawl and released alive west of the Mississippi River near West Pointe a la Hache (29.54322, -89.80227). Texas Texas’ records consisted of 53 sightings, 8 carcasses, and 5 captures (Appendices I, II, Figure 1). Twenty-one of the 66 records were previously published. The most records were from 1995 (20 sightings and 1 capture) and 2001 (12 sightings and 1 carcass). Eighty-six percent {n = 57) of the 66 records provided seasonal information; October and November had the most records with 14 and 12, respectively. Single individuals were most frequently sighted, and there were repeated sightings of a cow/calf pair in the Galveston Bay area in 1995. Six of the 21 published records were live captures from the southern Texas coast (Laguna Madre and Rio Grande) (Gunter 1941). Manatee sightings listed in Table 1 of Powell and Rathbun (1984) are in error, in that True (1884) mentions only one manatee for the GOM Coast. It was Gunter (1941) that is the correct source for a number of sightings (depending on interpretation, about 8 sight- ings, with some captures) in southern Texas. It appears that the numbers for those two source documents were trans- posed. The captures took place during 1853-1855 at Brazos, but sources did not specify Brazos Island or Brazos Santiago Pass. Specimen USNM 1375 at the US National Museum, Washington, DC, is one of those indi- viduals. Between 3 and 8 September 1995, a manatee cow/calf pair was sighted feeding on unidentified seagrasses in west Galveston Bay (Appendix I). There were repeated reports of these animals being sighted within 3 km of this location for the next week (Schiro and Fertl 1995). On 15 September 1995, the pair was seen near the west end of Galveston Island (Appendix I) (about 9 km east of San Luis Pass). Fishermen also sighted a cow/calf pair near North Deer Island on 18 September 1995 (Appendix I). All of these sightings were likely of the same pair. On 25 October 1995, a manatee was sighted at the Barney Davis Power Plant located on the Laguna Madre near the town of Flower Bluff. A second sighting was made 31 October 1995 at the Naval Air Station at Ingleside. On the morning of 2 November 1995, a manatee was observed throughout the day, several kilometers away at the Rockport Harbor and boat basin. Estimated body length was 305 cm, and the individual was determined by ventral observation to be a female. A notch on the right side of the tail, white marks above both eyes and a barnacle behind the right eye were noted. On 6 November 1995, a manatee with the same markings was swimming in a debris-strewn drainage ditch at the Koch Refinery on the Ea Quinta Channel, Corpus Christi. The manatee later moved into the Ea Quinta Channel heading towards the Central Power and Eight plant. Water temperature at that time was about 20 °C. On 8 November 1995, the same manatee was sight- ed and videotaped near the Texas State Aquarium (Appendix I). The final sighting was on 12 November 1995 in Port Aransas at the University of Texas Marine Science Institute (UTMSI) boat basin. The manatee remained in the basin throughout the day feeding on turtle grass {Thalassia testudinum), shoal grass (Halodule wrightii), and mangrove seeds. A scrape mark was observed behind the eye where the barnacle had been. The manatee was last observed and videotaped near dark at the far end of the Port Aransas Municipal Harbor (Appen- 72 Manatee Occurrence in the Northern Gule oe Mexico dix I). This was the last known sighting of this individual. Throughout late November and early December 1995, a single manatee was repeatedly sighted in Buffalo Bayou, just west of downtown Houston. This individual was most often observed at the warm-water outfall of a municipal wastewater treatment plant. On occasion, however, the manatee was seen leaving the canal, moving into the Houston Ship Channel. On one occasion, the individual was sighted 16 km downstream by a tow boat captain but was resighted the next day in its original location (Russel 1996). USFWS and Texas Parks and Wildlife Department (TPWD) personnel captured the manatee on 7 December 1995. The female manatee (313 cm) was moved to Sea World of Texas in San Antonio for temporary holding and nicknamed “Sweetpea.” Genetic analysis determined that she was a Florida manatee (R. Bonde, personal communi- cation, US Geological Survey, Florida Integrated Science Center, Sirenia Project, 412 NE 16th Avenue, Room 250, Gainesville, FL 32601, Garcia-Rodriguez et al. 1998). “Sweetpea” was later transferred to Sea World in Orlando, Florida and spent the winter rehabilitating at Homosassa Springs State Wildlife Park in Citrus County, Florida (Weigle et al. 2001). She was satellite-tagged and released at the headwaters of the Homosassa River on 23 April 1996 (Weigle et al. 2001). Once released, she swam north- ward along the west coast to the Florida Panhandle, spend- ing most of the spring and summer at sites around Apalachee Bay (Weigle et al. 2001). After moving west to Apalachicola Bay in September, she reversed her course and began heading south along the west coast, visiting var- ious locations before reaching Marathon in the Florida Keys in November 1996 (Weigle et al. 2001). “Sweetpea” then took a northeast turn along the Florida Keys and win- tered in south Miami. “Sweetpea’s” tag stopped transmit- ting in mid-March 1997 in Brevard County on Florida’s central east coast. Her last known location was where the Banana River joins the Indian River (Weigle et al. 2001). Her entire tag assembly, including belt, was recovered on 17 March 1999 in the Indian River, just south of Sebastian Creek (middle of Atlantic Coast of Florida) (Sirenia Project files). The belt had been cut (possibly by a pro- peller; however, this was not confirmed). She has not been sighted since. We believe that the manatee seen in late October and early November 1995 in Corpus Christi could be “Sweetpea”, based on fluke notches, similar size, and same sex, but confirmation is not possible. On 14 July 2001, TPWD personnel sighted a manatee in the Rockport area (Appendix I). During the last week of July 2001, a manatee was spotted in the UTMSI boat basin in Port Aransas (Appendix I). On 11 September 2001 a manatee estimated to be about 2.13 m in length was sighted in the Hampton’s Landing Boat Basin in Aransas Pass (Appendix I). On 23 September 2001, a manatee, estimat- ed to be about 1.83 m in length, was sighted in the inlet between the Texas State Aquarium and the Lexington Museum in Corpus Christi, Texas (Beaver 2001). On 3 October 2001, a manatee was videotaped near the Texas State Aquarium. Scars were observed on the left dorsum of the animal; however, the photograph quality was too poor to attempt a match to any known individual using identify- ing marks. This manatee spent time around the dock at the aquarium. Observers were able to determine that the indi- vidual was a male. A manatee was seen 1 1 Oct and 26 Oct near Portland (Appendix I), roughly 9.66 km from the aquarium. On 14 November 2001, a manatee was spotted at Valero Refining Company in Corpus Christi (Appendix I). When last seen, it was heading west towards Koch Refinery and the end of the Tule Lake Channel. On 29 November 2001, the manatee appeared emaciated to on- site biologists. A rescue attempt was initiated on 30 November 2001, but personnel from USFWS, Sea World, and UTMSI were unsuccessful in attempts to locate the manatee on 30 November 2001. The sightings from 29 and 30 November were in the inner harbor, where there are some warm-water outfalls. A manatee was seen again 5 and 12 December near Portland, in the same area as the 1 1 October 2001 sighting. Each of the reported sightings in November and December indicated that the manatee was becoming more lethargic and emaciated. On 12 December 2001, a cold front hit the area and dropped the air temper- atures to about 7 °C. Repeated trips to the area where the manatee had been sighted yielded no further sightings of the individual. During this same time period in October 2001, anoth- er individual was found dead and floating at Sargent Beach (Matagorda County), just off the Intracoastal Waterway, 241.4 km west of Port Aransas (Appendix II). The water temperature was about 23 °C. This manatee was a male, 3.05 m in length, and contrary to the editor’s note associ- ated with Beaver (2001), this could not be the same indi- vidual as reported above in the Port Aransas area. A tissue sample was collected from this individual and submitted for genetic analysis. This specimen matched the Florida manatee haplotype (R. Bonde, personal communication, Garcia-Rodriguez et al. 1998). Most recently, from late June to mid-August 2004, there were several sightings of manatees in south Texas (Appendix I). Seven sightings of one or perhaps even 2 individuals were reported in the area of Port Aransas and Corpus Christi Bay. 73 Fertl et al. Discussion Manatees occurring west of Florida and to the north of Mexico generally are considered to be strays originating from populations in either Florida or Mexico (e.g., Gunter 1941, Lowery 1974, Powell and Rathbun 1984, Domning and Hayek 1986). Many manatees in Florida make season- al movements northward in spring and southward in the fall (Moore 1951a, Powell and Rathbun 1984). Coinciding with these movements, manatees in Mexico move north into Tamaulipas (near the US/Mexico border) during the rainy season (May through September) (Lazcano-Barrero and Packard 1989). The most likely source of emigrants along the GOM coast would be manatees that over-winter in the headwaters of the Crystal and Homosassa rivers, as well as perhaps the Tampa-Ft. Myers region (Bonde and Lefebvre 2001). This is supported by the photographic matches made to manatees sighted in Alabama and Louisiana, as well as genetic analyses of tissue samples from two individuals found in Texas. Researchers have documented wide-ranging move- ments by some West Indian manatees. Data for some indi- viduals in Florida suggest a traditional long-range season- al migration along the Atlantic coast (Reid et al. 1991, Deutsch et al. 2003). Annual movements in excess of 1,700 km (round trip) have been documented for one radio- tagged manatee on the Atlantic coast. “Chessie” moved between Florida and the Chesapeake Bay in multiple years and one year migrated as far as Rhode Island (Deutsch et al. 2003). “Gina,” a manatee photo-identified as a calf and juvenile in the Homosassa River on the GOM coast of Florida, has been living in the Bahamas since about 1996 (Reid 2000, Lefebvre et al. 2001). A manatee hit by a crew boat in Louisiana was photo-identified in the Tampa Bay area (Anonymous 1996, FWC files), a minimum coastal distance of 618 km. Two manatees were sighted in the Dry Tortugas in 1982 (Reynolds and Ferguson 1984), and a wayward manatee radio-tagged at Crystal River in north- west Florida was rescued just six weeks later off the Dry Tortugas in 1998 (Sirenia Project files). Hartman (1979) also mentioned sightings of manatees in the Dry Tortugas. The impetus for wide ranging movements is not always apparent but is likely in response to environmental cues; for males, it may be a strategy for mate- searching as well (Deutsch et al. 2003). We found manatees to be most common in estuarine and river mouth habitats and rare in the open ocean. This observation mirrors their natural history, although data col- lection is heavily skewed to coastal observations. This habitat preference has been noted by other sources (Moore 1951b, Hartman 1979, Rathbun et al. 1982). Occasionally manatees may wander into deep waters. Schwartz (1995) commented on the rare occurrence of open ocean sightings off North Carolina. A manatee was sighted about 12.87 km off the Louisiana coast in early July 1979 (Gunter and Corcoran 1981). More recently, a manatee was sighted on 15 October 2001 about 144.8 km south of Mobile Bay, in waters over the Mississippi Canyon in Minerals Management Service’s Lease Block Mississippi Canyon 85 during oil and gas exploration operations (Anonymous 2001; T. Pitchford, personal communication, Florida Fish and Wildlife Conservation Commission, Marine Mammal Pathobiology Laboratory, 3700 54th Avenue, South, St. Petersburg, FL 33711; Sirenia Project files). The exact location of the manatee was not recorded, but the center coordinates for this 3 square mile block are -87.94482, 28.91394, with a bottom depth greater than 1,524 m (Sirenia Project files), not 914.4 m as reported by Anonymous (2001). The manatee was sighted for a few days around operating vessels and was even observed to feed on algae growth on the bottom of the vessel. Efforts were underway to attempt a rescue, but the manatee disap- peared when several large sharks were seen in the vicinity. The manatee was last sighted on 17 October 2001, and its fate remains unknown. During the warm season, adult males are considered to range over wider areas than females and subadults (Bengtson 1981, Deutsch et al. 2003). Based on five man- atees captured or stranded in South Carolina and Georgia, Rathbun et al. (1982) suggested that extralimital animals would mostly be males. Information on the age or sex for most of the individuals in this review was not available; however, we were able to determine that all age and sex classes appear to make extended range movements. Interestingly, 7% of all the occurrence records were of cow/calf pairs. Deutsch et al. (2003) found that subadults in the Atlantic subpopulation demonstrated strong philopa- try to specific warm-season ranges that they had occupied as calves, and some followed the same migratory patterns as their mothers. Access to warm water, freshwater, and food is required by manatees (Hartman 1979). Temperature is the overriding factor in determining the geographic extent of suitable habitat to manatees (Smith 1993). The vulnerabil- ity of manatees to cool ambient water temperatures is well- documented (Moore 1951b, O’Shea et al. 1985, Miculka and Worthy 1995). Manatee deaths attributed to exposure to cold were recorded as early as the 19th century (Moore 1951b, O’Shea et al. 1985, Ackerman et al. 1995). Data suggest that manatees possess metabolic rates that are only 25-30% of predicted values (Gallivan and Best 1980, Irvine 1983, Miculka and Worthy 1995), resulting in a lack 74 Manatee Occurrence in the Northern Gule oe Mexico of cold tolerance. Young manatees (< 300 kg) are even more susceptible to cold than adults because they are apparently incapable of increasing metabolic rate at low temperatures (Miculka and Worthy 1995), possibly result- ing in hypothermia and death. To offset these metabolic insufficiencies, manatees respond to cold weather by relo- cating to thermal refuges, either natural spring or warm- water industrial effluents. As noted by Moore (1951b), large springs have immense flow averages that can supply water at 22 °C much faster than the air can chill it. Mothers introduce their offspring to warm- water refuges during the prolonged period of dependence common to the species (Hartman 1979, Deutsch et al. 2003). This suggests the possibility that in the future there may be increased dependence on warm-water sites along the northern GOM. We observed signs similar to those described as cold-stress in many of the manatees found dead west of Florida. Several of the winter sightings were at natural warm springs and industrial warm-water effluents. Residents near some warm-water springs in Alabama report regularly seeing manatees over the past 40 years. They consider these sightings unremarkable. There are probably other localized areas along the northern GOM coast where forage is available and water temperatures might be high enough and consistently reliable to support manatees through the winter. For example, manatees have been seen near power plant and wastewater treatment plant effluents in both Louisiana and Texas, particularly during winter months. Additionally, the USFWS (2001) noted that canals and boat basins, where warmer water temperatures persist as temperatures in adjacent bays and rivers decline, might also be used as temporary thermal refuges. Manatees in this study were often observed in such habitats. Gunter (1941) reported that all manatees observed in Texas at the time were seen during the summer months and that manatee presence would be precluded in any part of Texas during midwinter. Powell and Rathbun (1984) sug- gested that sightings have declined in frequency and that all have occurred during the summer. While there were many records for summer, we noted a considerable num- ber of more recent winter sightings as well. These individ- uals concentrated their movements in boat basins and at power plant effluents. In addition, the public is more aware of the sensitivity of manatees to cold than in the past. Access to freshwater also influences the movements of manatees. Manatees are attracted to freshwater from natural sources such as rivers and springs, as well as from anthropogenic sources such as wastewater or storm-water outfalls, drainage pipes, and garden hoses (O’Shea and Kochman 1990, Lefebvre et al. 2001, Weigle et al. 2001). Osmoregulatory studies demonstrate that while manatees can cope with brackish water environments, they cannot survive prolonged exposure to the marine environment unless they can visit freshwater sources on a regular basis (Ortiz et al. 1998). Seagrasses are a main component of a manatee’s diet in coastal areas (Lefebvre et al. 2000); although Florida manatees are generalists, feeding on a wide variety of aquatic vegetation, emergent or terrestrial vegetation, algae, grass trimmings from mowing, and fish carcasses (e.g., Powell 1978, Smith 1993, Baugh et al. 1999, Lefebvre et al. 2000, 2001). Some seagrass-associated invertebrates may be incidentally consumed during forag- ing on vegetation (e.g., Mignucci and Beck 1998); howev- er, they may also be preferentially ingested (Courbis and Worthy 2003). Lefebvre et al. (2000) suggested that Florida manatees benefit the most by eating available for- age in proximity to their refuges or travel routes. Seagrass beds of Thalassia and Halodule are more extensive from Mobile Bay to Florida Bay than in the rest of the GOM (Handley 1995). These seagrasses west of Mobile Bay exist only in isolated patches and in narrow bands to Aransas Bay, Texas (Handley 1995). Freshwater sub- merged aquatic vegetation also occurs throughout GOM estuaries and river deltas (Handley 1995). Manatee grass {Syringodium filiforme) and shoal grass {Halodule wrightii) are the dominant seagrasses found in the shallow water on the northern side of the barrier islands of Mississippi (Handley 1995). Coastal Louisiana has a large amount of submerged aquatic vegetation, with only a small portion of this being seagrasses (Handley 1995). The only remaining seagrass beds in coastal Louisiana exist in Chandeleur Sound (Handley 1995). There is a wide distri- bution of seagrasses, predominantly shoal grass and wid- geon grass {Ruppia maritima), in the Galveston Bay estu- ary (Handley 1995). Seagrasses are prevalent in Laguna Madre (Onuf 1995). Seagrass meadows are increasing in upper Laguna Madre; however, they are on the decrease in lower Laguna Madre (Onuf 1995). There are small patch- es of shoal grass and widgeon grass {Ruppia maritima) in the Corpus Christi Bay area (McCullough 2001, Pulich et al. 1997) and patches of red turf algae {Gelidium spp.) and sea lettuce {Ulva spp.) (L. Price-May, personal observa- tion). We compiled various reports of manatees feeding west of Florida. One manatee in Port Aransas, Texas was observed to feed on loose sea grasses such as turtle grass {Thalassia testudinum), shoal grass, cordgrass {Spartina spp.), mangrove seeds, and other vegetable material. A manatee cow-calf pair was seen feeding on seagrasses (unidentified species) in Galveston Bay, Texas. Additionally, one manatee sighted in the Natalbany River 75 Fertl et al. (Louisiana) was feeding on lilies (unidentified species), a second was sighted in Lake Maurepas (Louisiana) in a Hydrilla (Hydrilla spp.) bed, while another in open water off the southwest tip of the Chandeleur Islands was feed- ing on a weed line at the water’s surface. There is evidence that manatees can be temporarily independent of warm water, perhaps moving to nearby sea- grass beds to feed (Bengtson 1981, Shane 1984, Deutsch et al. 2003). Some of the animals reported in the present study in the vicinity of New Orleans, Houston, and Port Aransas (described in detail earlier) were often observed leaving warm-water refuges, only to return several hours later, perhaps having consumed food. Periodic movements from wintering sites at Blue Springs, Florida, and at power plants have been noted (Bengtson 1981, Irvine 1983, Deutsch et al. 2003). As suggested by Smith (1993), it is probable that manatees may leave warm-water areas only after air and adjacent water temperatures have risen in the afternoon and only after cold fronts have passed. Several Alabama manatees were sighted in warm-water refuges without food resources; however, nearby waters could sup- ply an abundance of food. Irvine (1983) noted that mana- tees would leave warm-water refuges to feed in cooler waters only if they can shortly return to the warmer water temperatures to digest their food. Traveling manatees use warm-water refuges along their migratory routes during both the early spring and late fall in a ‘stepping-stone’ strategy, which may permit them to migrate earlier in the spring as well as remain at sites later into the fall (Reid et al. 1991, Deutsch et al. 2003). Individuals may disperse during intervening periods of mild weather with warmer temperatures (Moore 1956, Hartman 1979, Shane 1984, Reid et al. 1991). Numerous sightings, for example in lakes St. Catherine and Pontchartrain in Louisiana, northern Mobile Bay in Alabama, and Corpus Christ! Bay /Laguna Madre in Texas, suggest repeated use of certain areas. Individual manatees in Florida and Georgia are known to return to the same winter ranges each year, and some may also return to the same summer ranges (Rathbun et al. 1982, 1990, Koelsch 1997, Deutsch et al. 2003). Seasonal site fidelity has also been noted for some radio-tagged manatees fre- quenting southeastern Georgia (Zoodsma 1991). It is not known whether the manatees mentioned in this paper were the same individuals returning annually to the same area. More attempts to photo-identify these strays would pro- vide additional information. Studies also should be con- ducted to characterize the habitat in these areas to deter- mine what might attract individuals and ensure proper management strategies. The reasons are not known for the large number of extralimital sightings of this species along the GOM. Collard et al. (1976) noted that as the health of northern GOM estuaries and their associated flora improves, the excursion range of manatees may broaden. Bonde and Lefebvre (2001) suggested that the increase in sightings might have been made possible by man-made sources of warm waters (such as industrial effluents), as well as a decade of relatively warm winters. Storm events and a cli- matic trend of warmer winters and summers may also help to explain increased extralimital movements by manatees (Lefebvre et al. 2001). In Texas and Louisiana, we noted a peak in 1995 of the number of manatee sightings west of Florida. The 1995 hurricane season was a notably active one for major storms, with 19 named storms (the mean is nine), 11 of which became hurricanes (the mean is five) (Williams and Duedall 1997). It was not a record but a close second to the 1933 season of 21 storms (Williams and Duedall 1997). Langtimm and Beck (2003) deter- mined significant annual variation in adult manatee sur- vival in years when intense hurricanes and a major winter storm occurred in the northern GOM. Many of the mana- tee sightings we compiled for west of Florida occurred after four hurricanes and three tropical storms entered the GOM in 1995; several of these storms directly impacted Florida and the Yucatan Peninsula. As noted by Langtimm and Beck (2003), a storm might cause manatees to emi- grate from Florida either voluntarily (in response to cooled surface waters which follow in the wake of a hurricane and can persist for days) or involuntarily (e.g., by strong long- shore currents or high-energy waves). For example, a man- atee was sighted in Theodore Channel in Alabama during Hurricane Opal in October 1995. The growing public awareness of the manatee also may be a sufficient explana- tion for the increased number of reports (Rathbun et al. 1982, Schwartz 1995, Lefebvre et al. 2001, Schleifstein 2004). Lastly, the increase in extralimital sightings west of Florida is probably due to animals moving from the south- ern Big Bend coast, where their numbers have increased (Rathbun et al. 1990, Bonde and Lefebvre 2001). From this review, it is obvious that small numbers of manatees occasionally migrate through the northern GOM from Florida and possibly Mexico. Because of these move- ment patterns, environmental planners and managers need to consider the likelihood that manatees may be affected by a variety of human activities in coastal waters (as well as deeper waters, on occasion) of the northern GOM. Increased attention also must be given to the protection of habitat resources throughout the manatee’s travel corridors (Smith 1993). For example, Handley (1995) notes that losses of seagrasses in the northern GOM have been exten- 76 Manatee Occurrence in the Northern Gule oe Mexico sive, varying 20-100% for most estuaries. As in Florida, alterations to both natural and industrial warm-water refuges along the rest of the GOM coast have significant implications for manatees (USFWS 2001). For example, human activities in the vicinity of these springs and the use of aquifer waters are a threat to the availability and suit- ability of spring waters to manatees. If the volume of water flowing from springs decreases, available and accessible habitat and water temperature around springs may drop, increasing manatees’ exposure to cold waters and its asso- ciated health risks. The status of manatees as an endan- gered species makes the loss of individual manatees bio- logically significant. We hope that this compilation will stimulate further investigations of manatee distribution west of Florida in the northern GOM and serve as contin- ued encouragement for people to report occurrences of manatees to appropriate personnel. To that end, it is requested that future manatee observations be reported to the appropriate authorities in each state and to the USFWS’ Jacksonville Field Office, which is charged with the daily management of the Florida manatee and holds the recovery lead for the species. A secure, electronic database is maintained to record and track all manatee sightings, rescues, and deaths outside the state of Florida. To con- tribute data to the manatee sighting and stranding network contact the USFWS office at 904-232-2580, extension 123 to receive a username and password. A yearly summary for all out-of-state manatee activity is sent to all manatee stranding network partners. Acknowledgments Regional stranding networks from Alabama, Mississippi, Louisiana, and Texas, as well as the FWC’s Marine Pathobiology Lab provided a great deal of assis- tance. We thank B. Kimmy and S. O’ Hare with the Alabama Marine Mammal Stranding Network; I. Maxit, S. Shively, and G. Lester with the Louisiana Natural Heritage Program (Louisiana Department of Wildlife and Fisheries); J. Siegel and M. Solangi of the Marine Life Oceanarium in Gulfport, Mississippi; K. Rademacher and K. Mullin at National Marine Fisheries Service in Pascagoula, Mississippi; L. Clark and B. Bloodsworth with the Texas Marine Mammal Stranding Network; and T. Pitchford and K. Arrison with the Marine Mammal Pathobiology Laboratory (FWC). We also thank D. Hockaday for providing unpublished reports. B. Ackerman, C. Deutsch, D. Domning, L. Lefebvre, J. Litz, S. Pomes, V. Reggio, and S. Tarr provided follow-up infor- mation and assisted with locating references. B. Ackerman, R. Bonde, L. Lefebvre, and S. Wright provided insightful comments on earlier drafts. I. Moreno and M. Grushka assisted with the manuscript preparation. We are especially grateful to B. Ackerman and L. Lefebvre for their constant encouragement to complete this paper, G.L. 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University of Elorida, Gainesville, PL, USA, 202 p. 79 hM Q a 2 'u o O) o o 'S O) < 4-1 o 2 o ;n O) ■M Lm o a a> u o o O) ;m W) a ’■3 •Sf o^ a\ d d d d d d d d d d d d d d d d d d d d d d d d d d d ^H d d d d d d d d d d d d d d d d d d d d d d d d d d d ^ ^ ^ ^ 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 d d d d d d X X X 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 Sh -d 43 d d d d d d d d d d d d d d d d d d d d d d d d d d d P GO GO 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 04 o d d d d d d d d d d d d d d d d d d d d d d d d d d d O o d d d d d d d d d d d d d d d d d d d d d d d d d d d 2 [> 2 d hH d 1— H 1— H 1— H 1— H 1— H 1— H m 1— H 1— H 1— H ^H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 04^ Z O) m m m o m o m m o o m m cn X O m § oo 00 X in § 00 § in m § m X in in m i-H X 00 X 00 § 00 in B m (N in oo d- in d- 00 o (N (N m in o d- in d- in i—H d- o d- O d- o^ in o 00 (N (N X d- 00 d- H o o 00 00 m H (N m (N m (N (N in in in m o^ ’5i) a\ XI 00 00 '^H in X r- q y—i ■^H q H X q H 1— H o^ H q q o^ in in in c^ q 1— H d A OO 00 00 00 oo 00 oo 00 00 00 oo 00 00 w hQ 00 00 00 1 00 1 oo 1 00 1 00 1 00 1 00 00 o«p oo 00 o«p oo o«p oo 00 1 00 1 00 1 oo 1 00 1 00 1 oo 1 00 1 00 1 o«p 00 00 O) a\ o m r- m m o m o m m r- cn r-- r- o m m r- r-- r- in r- 'P (N 00 X oo m in m o m m X X 00 i-H X o 00 X m X X X i-H X d m § (N Tj- (N oo m in oo t-H 00 oo (N (N X d- (N r- oo O C3n H C3n H in (N ■HH o 00 m m m d- m m in 00 X 00 00 a\ m m 00 00 00 C3^ o^ o^ in d- ’■S q (N 7l- d- in (N (N (N m (N in m (N m in in X d- X X in 00 (N (N (N q d- d -1 H d d d d d d d d d d d d d d d d d d d d d d d d d d 1— H d M m m m CO m m m m cn m m m m m m m m m m cn m m m m m m m m o o^ o^ 00 o^ S' S -i d S X) W) t/D d d o d « o O H PQ _ d S 3 o ^ 3 2 2 d iH d d Oh 43 U O O) O) bX) -o ,d • ^ ^-hH C/^ (1^ d (D O d 43 2 d > 43 Oh d d Q d o d PQ d _d d 2 Vh d d 4^ d Q 2 0:h Ca Q^ bX) bX) o o Q Q d d -d O 2 a bX) _d 2 PQ Vh d d d r2* p5 <1^ d 4^ d O d o a t> m 5^ Qp d d d d 73 d d PQ 4^ d o 2^ O U h-H ^ ^ ? d -d d d -- Qi^ d vh PQ £ :d 2 c* 2 Q o ^ a o ^ u - & s ^ (U d Q m -8 2 2 d ^ a & 5 d d d a u a 73 d u d d .d PQ PQ o: o o > 'd 73 ^ 0^ .> 2 73 73 ^ ^ ^ Ch <0 > H f~\ > > > > > > > T— H S-H >> o (U > > o o o o o o o CO ;h C4 c3 cd H- 5 O Q Q Q 2 2 GO O O o o o 2 2 o ns C4 C4 C4 < 2 2 >— 5 m t-H cn X in t-H t-H >— 5 ON ON X X X r-H T— H d- in X 00 X U <; O d- (ON 00 (N (N m m 1— H (N (N m d- oo ON T— H ^-H r-H (N X r-H m ON (N (N y^ d 2 o 00 d 43 bX) ffi _d ’d d o^ in ffi d _o d d o o d d d X) in b-. ffi 73 d tP o 04 d Date Location description Latitude Longitude No. Individ. Source ALABAMA (continued) week of 25 Jun 1995 mouth of Fowl River, western shore side 30.45133 -88.10817 2 (c/c) unpub. data 4 Jul 1995 Tensaw River, Hurricane Bayou 30.83750 -87.90467 1 unpub. data 14 Sep 1995 Tensaw River, south end of Gravine Island 30.77283 -87.92933 4 unpub. data +3 +3 +3 +3 +3 +3 +3 +3 +3 +3 +3 +3 +3 +3 +3 +3 a +3 +3 +3 +3 +3 d d d d d d d d d "c^ d d d d d d d d d d -a -13 -o -73 73 -^3 -13 73 73 -13 -a 73 33 33 33 33 33 33 33 33 33 33 33 33 33 -d ..d .d ..d .d rd .d rd -d xi .d xi 43 X5 43 43 43 43 43 43 43 43 Xi 3 3 3 3 3 3 3 3 3 3 3 35 35 d d d d d d d d d d d d Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh C C C C C C C C C C C C C C C C C C d d d d d d d d d d d d d 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 d d d d d d d d d d d d d o o o "o m ^ in ^ ^ CN O m m o o o o O t-- o r- m m O m m m m r- r- m m o in m m o o o o X m 00 00 in 00 00 00 m X X i—H X X X 00 00 in X X o^ oo § m m m m d- in r- o o 00 m o m T— 1 X X in in (N ON (N (N T— i d- d- o o o o (N 00 m m H (N (N 1— H (N o X H X X m m o > o > o > o > o o (D Vh C4 34 < u 34 < On 'o ON 3 tJ) o < OX) o < 34 O GO 34 i— 5 o ON ON (N o o in OO in 00 d- d- X in in i— 5 (N (N d- (N X (N (N (N m (N (N (N 00 (N (N (N ON (N d- cb cb B cb cb g g cb cb cb g cb cb cb cb cb cb cb cb cb g B B g cb cb cb g cb g tb cb tb tb "cb cb tb tb tb tb tb tb tb tb tb tb tb tb tb tb tb cb cb tb tb tb tb tb tb tb 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 33 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 3 3 3 :3 O 3 35 35 35 3 3 35 O 3 35 O 3 :3 3 3 3 35 3 3 35 3 3 35 3 :3 Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh O O o o O i3 O O O O O O O i3 O o O o O O O O i3 O O O O i3 O o o o o o o 3 o o o o o o o O o o o o o o o o 3 o o o o 3 o o S a a o o HH Q 2 lo lo k I w fi hH d CO CO X CO CO in in 3t 3t QJ m CO CO o- o- CO CO o CO CO CO CO o CO CO CO o CO o CO CO m 00 m t-H 00 H 00 in 00 00 o CO CO o in 00 00 X i-H X 00 o CO X o in 00 CO X P X 00 00 3t 3t 04 O 04 04 00 o 00 CO CO 04 in 00 00 in 04 00 CO in in in 00 a\ o o a\ 00 00 o^ o^ 04 04 CO 3t 3t 1— H 04 o CO X X o 04 CO X 04 04 04 CO X o W) r-; q q q q q oo 1— H 1— H q q 04 04 q q X q q q q q q q q 1— H q 0 00 00 o6 00 00 00 00 00 oo 00 00 oo 00 00 00 00 w hQ 00 00 00 00 oo 00 00 00 00 oo 00 00 oo 00 00 00 00 00 oo 00 00 00 q oo GO q q q q q O) r- o o r- r- o CO CO o CO o CO o o r- o CO r- CO O CO O O CO O X H in in X X X o CO CO in CO in 00 in o X in 00 X 00 O 1— H 00 m o CO o S o^ 00 04 04 X X in 3t o in o o o^ 04 04 00 00 o 04 o^ m X o H 04 04 X X CO X X a\ 3l- o o^ oo CO o^ 3t r- o^ § O X X 00 04 o oo '■^ 04 04 in in in in in 3t 04 04 oo 00 3j- 3t in in CO X 04 04 00 3t a\ X X 3t 3t 3i- in cb hQ d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d CO CO CO m CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO CO S o o X) m a> I PQ o CIh :3 (U Dh C3 O <1^ o r^H fi ^ >> (U £ S c« c c3 u Br 00 o -13 O -C H c^ c a U Oh S 00 o o lU X! H !h C^ (U C 3 o a PQ Sh O c5 03 a 33 H < o o Q o X > psi psi Q< •S -a tp X) 2 ^ c o c/3 C3 03 PQ ^ C3 t3 S I ■§ ,D B C3 _g S c3 o 2 33 l3 C3 'c3 s 0 01 bX) 33 2 Sh Vh 5 <3 <3 O 2 S cn rin s 33 S3 C3 C3 C/D c <3h o Ob o tS cb s! « .2 2S ^ U I PLh c3 Cb b^ C3 Ob I ^ (N 03 PQ r2 O U "S I! ^ C3 ffi >. ■3 :2 - -8 (/3 i3 Ob C3 o ’B u B bX) c3 .2 ^ 33 C3 Ob 33 ;=3 33 pb ^T< fTi >, bO bO S3 cb O O O PQ Q Q PQ o B o S I a ^ ^ -S PQ § m J o ■psP 2 03 c/3 Pa PQ Ob Ob s cb O C3 o o O o o O O O O o o Q (3 (3 04 04 04 04 04 04 04 04 04 04 04 O o o 1—5 1— s i— 5 •—5 i— ) I—) i— ) •—5 35 O O »— 5 Cb 04 04 04 CO in in o^ •— 5 •— ) 1—) Q t-H 04 04 04 04 04 04 04 m X On ^ o bX) (N O OX Q 2 O vh*^ bX)bX)bX)bJOcb '^C3bX):333535(lb cnoolno^co'sOO^'-^t^t^^ (cn^oxoxmox^oxoxm^^ox o ox S3 cb OX 00 bX) o Q o C3 cb XI Date Location description Latitude Longitude No. Individ. Source ALABAMA (continued) 1 Apr 2002 Perdido Pass area 30.28033 -87.54833 1 unpub. data 17 Apr 2002 Perdido Bay, Old River, under bridge to Ono Island 30.28033 -87.53617 1 unpub. data 18 Apr 2002 Perdido Bay, Old River by Ono Island 30.28033 -87.53617 1 unpub. data p p p p p p B B p B p p p p B B p B p p B p B p p B p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p -p -TP -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p -p pp PP PC pc pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp pp X) p P p p p p p p p p p p p p p p p p p p p p p p p p p p p p CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP CP p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p p o m r-- m m o m CO m (N o t-H m o 00 (N cn in cn in NO NO H NO m NO NO 00 m NO o T—i 00 00 NO m (N in (N m (N m NO in NO cn ON m ON NO m ON ON m 00 P- C-- NO m (N (N 00 m ON (N p- m m in m ON (N in P- (N in (N P- m (N o o m NO NO m in CO p- ,-H P- 00 (N p- (N p- NO NO ON in in ON (N in ON in C-; NO H r-; q q q q in q q in in q q O) q q q q 00 oo 00 00 00 00 oo 00 00 oo 00 00 oo 00 00 00 oo 00 00 00 00 00 00 00 00 oo 00 00 oo 00 00 oo 00 o m O o r- (N o o m m o r- o ON (N ON o NO o ON CO o 00 in m o 00 in o NO o in 00 H m in NO NO NO o m (N o m m 00 o m (N 00 (N in o in ON ON (N o (N ON ON in in 00 00 NO ON (N in p- OO ON NO NO o NO 00 o o 00 r- o o 00 r- (N p- 00 00 00 P- o cn oo in 00 OO NO ON m (N p- (N m ON (N (N (N in in (N in in NO m (N (N NO p- m (N (N in NO p- (N (N P- d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d m m m m m m m m m m m m m m m m m m m m m m m m m m cn m m m 00 U o Ph (N % I s I to c/3 P >> p o p o p >> PQ d p p 0*^ U p C/!i p p p HH U C/!) p 3 Bk p p 1 C/} cd Oh P O 'B o l+H o p 1 P P3 P P p p Bk p p PL| P o p 1 p ‘o _p ’c/3 P B c/3 P o o OX) p o Xh 3 c/3 P o P d P _p 'c/3 P O 3 c/3 p o Qh p a PQ p p cn p d PQ 2 OX) o Q 0) o o s s o o X) o 3 u o C .CO O >H O j_, op S 03 (U ^ s D 5 O J PQ 'o 'o ^ s ir! ^ (U c« D c3 g Ph o o 3 a PQ Oh 0^ 03 03 ■§ Q Oi .P CIh -O U U ^ t ^ c 3 o U iP c3 ^ 3 "cO PQ o o a o C3 C/3 o I ^ § 03 O o hJ a iP y ^a ’h-i c3 O PP ^ c/3 't; T3 o CO o U u .a 'p p u p OX) p o p p p PQ PQ p p y p p o [jp <-! Vh P •—5 i— 5 1— > i— 5 P P •—5 (N P- in NO 00 o 1—5 •— ) P- (N H (N m (N NO (N ^ ^ ^ ^ (N O o OX) OX) OX) OX) (N p p p p (N (N (N (N < < < < ^ ON o ^ ^ (N (N m p- (N t) o 00 (N m m m o m o s s (N o o o o — H cn in p- p- P- p- p- § P- p- o (N O o o o o o o o (N (N (N (N (N (N P P P P P P P P P P P P i— 5 •—5 1—5 i— 5 p- 1—) 1—5 (N in 00 o (N in 00 m S a a o o HH Q o QJ ■M ’So o cb cb 3 3 bp bp X X o o Oh Oh o o O O c/3 -3 ^ o »n m M PLh o o >N d* cb PQ 3 d p M o 3 .d ^ 3 X >N P Cb o M s C3 PQ P. P _> '■^ a o p rM 3 d X o 3 d bX) O Q Cm c/3 o PQ O P 3 c/3 3 3 hQ C/3 P 3 o cb P 3 .-O d <13 bt bt bt bt 00 oo 00 00 CPN (PN ON ON ■(— H o o o o o O O o hO X X JG X X X X 3 3 3 3 d d d d bp bp bp bp o o o o cb cb cb cb 3 3 3 3 o o o o Ph Ph Ph Ph 00 ^ Qs, ^ ON 00 2 S 2 ° T— H ON ON 2 § O x> 3 5 O C3 u o a ci U Qi bp bp bp bp bp cb cb cb cb cb cb cb cb cb cb cb O O O o O 3 3 3 3 3 3 3 3 3 3 3 cb cb cb cb cb bp bp bp bp bp bp bp bp bp bp bp M 1 M 1 1 p 3 p 3 3 X d X X X X d d d d d l-H l-H o o O o o o o o o o o 00 Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh (PN o o P o o o o o o o o o o o o o o Oh Ph Ph O o O o o O o o o o o o o NO NO o (N 00 m o 00 o o bt in bt (N (PN i(— H r- in O m O in 00 00 t-H o m NO NO bt (N in m (N in m m bt bt in 00 (N NO in NO NO 00 o 00 00 NO 00 00 bt 00 bt (N NO NO 00 (N q (N (N o o in q q in m H bt q OO q q q 00 00 (PN (PN (PN ON 00 00 00 (ON (ON CPN ON (ON (ON 00 00 00 00 00 00 00 00 00 1 00 1 00 1 00 1 00 1 00 00 00 o«p o«p 00 00 00 00 o«p o«p o«p m o (PN o o NO NO in (ON NO O (ON r- bt m m bt (PN m o O NO in o 00 (N m bt in m m 00 00 o NO oo o in m NO (N 00 H O 00 r- 00 m m NO NO 00 NO in in NO in (N NO H ON in m bt m m NO m 00 m 00 »n in cn m m m in bt bt m m m (N m cn m m bt NO (d (d d d d d d ON d d d d d d d d d d d d m m m m cn m m (N m m m m m m m m m m m cn ^ 55 oi os M i! i: HH O O § S ^ GO cb O O -o a o o GO ’Sh Oh 3 o »n d d o 3 O 3 a cb o cb ^ O c /3 _0 Cb Ip O cb u ffi d d o O O bX) n 3 3^ O O Cd cb a cb o o d a cb o PQ Oh 2 ’i ^ I GO 3 3 t bp g o 3 o Cl, l'“ O D O ^ Hh'' 3 OJ PLh Oh .3 Ch S Cb c /3 § s Oi I u cb (D 3 cb Oh

M o 2 3 (D o bp" o o o GO 'Oh 1m O bp bp cb bt bt 00 o O (PN o O (N (N P 3 H- > 3 1—5 P Q bt NO rM (N (N m (PN (PN CPN CPN Q\ r- ON (PN CPN CPN H o^ C C C cd Cb Cb Cb H-5 :3 1—5 1—5 1—5 OO H- 5 H— H m in ^ I g o o ^ 00 (N ON ^ CO 2 «!' = - O S PQ ^ ■13 o o 3 3 ^ d c/5 ^ 3“ 3 m -3 ON ON C3N (ON O o Oh 3 o o o' o 3 S fi^ O ^ d 3 2 2 o GO UN ON ON ON u 'o o ^ o c/3 bp <0 bp tx O o 2 3 d'' o 3^ S X o cb (U PQ 3 o s G-h o X 3 o 2 cb d* ^ 2 ^ 2 X S W § M ^ S T o M (P (P M 3 ^ Cb d o 3 PQ p > d p 3 d o d O d >N Cb PQ p cb PQ o o p c/3 Cb Oh $ X 3 o 2 p X p 2 2 O NO NO GO (N ^ > O bX) bXX o o < < O CO bX) o < o (N ON (ON ^ ON bX) 3 < ^ 3 ON ON (ON bX) O < r- (N o 2 o 2 o U bp o cb O O O d o o p bp o cb O o PQ o o bp o cb P bX) O ■p X c/3 Cb 3 o p p bp p d o Oh P bl- oc ON bt 00 Date Location description Latitude Longitude No. Individ. Source MISSISSIPPI (continued) 8 Feb 2001 Horn Island 30.23000 -88.68000 1 unpub. data 7 Jul 2001 Moses Pier, Gulfport Harbor 30.35364 -89.07972 1 unpub. data 30 Oct 2001 Gulfport small craft harbor, next to Mississippi Aquarium 30.33714 -89.09977 1 unpub. data d d d d d d d d d d d d -a -d -d -d -d -d rd rd xS rX, rXl d d d d d d Oh Oh Oh Oh Oh Oh d d d d d d d d d d d d S o 1 o o m dn Oh 03 d o 3 c o a ^ .a c I •-H ^ c3 O -Td ’B a o c/3 C/3 bX) d 00 ^ O c3 ^ U o^ o 73 d d Vh (U II d- 00 On d d -o d -a d d lo o Ph 0 0 0 0 d\ a\ ON ON o^ o^ ON ON T— H T— H T— H ; ; ; ; d d d d d d d d d d d d d d d d xi -O -d d d d d Pxi P^ 00 00 00 00 00 o^ ON ON ON H H H ^ ^ ^ ^ ^ ^ d d d d d d d d -d -d -d -d GO GO GO GO b b b b d d d d d d d d d d d d d d d d d d d d -o -o -o 73 -o 73 73 73 rXl rd> -d Xi .d dG d d d d d d d d d d Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh d d d d d d d d d d d d d d d d d d d d NO CO ON d- in (N 00 (N 0 (N NO NO in (N 0 CO NO 0 in Tj- CO NO NO CO d- ON in ON r- 0 0 ON ON NO in NO 00 in (N CO 0 ON in 0 ON (N (N in H CO (N 0 (N 00 NO (N (N in 0 CO 0 in d- r-- (N NO 00 in 00 ON 0 ON 0 ON (N NO (N d- d- CO ON CO CO 00 CO 00 ON 00 00 d- ON 06 ON 06 ON ON ON d d d d d d d d ON d d d ON d ON 00 00 00 00 00 00 00 ON ON ON ON ON ON ON ON ON 00 ON ON ON 00 ON 00 H NO 00 r- 1— H in CO (N 00 r- in ON CO in 0 0 (N 0 NO CO 0 CO CO NO in 0 r- NO (N ON d- 0 0 (N d- 0 in m NO 0 0 (N 0 NO ON 00 NO in d- NO 00 0 H ON NO CO CO H (N in (N ON ON d- r- CO d- 0 r- in d- (N m d- CO CO CO (N 0 NO CO (N (N CO d- CO (N CO NO (N 00 0 (N d d d d d d d d ON d d d d d d d ON d On d ON d d CO CO CO CO CO CO CO CO (N CO CO CO CO CO CO CO (N CO (N CO (N CO CO a Jo 0 d d c /1 PQ <0 X 0 ‘C C/3 > "-M > 4:3 u 'B 0 C3 0 IpH c/5 C/1 d To in 'o CIh hH C/2 HH o o Ph -o d d O <0 d <0 _d ■S d u o o (N > O (N (N (N CO CO CO ■d" 0 0 0 0 (ON 0 (N 0 (N 0 CN (N (N X 3 X d CO 00 Q <10 lx 00 X d •— ) 0 (N 00 00 T— H (N (N 00 1C IS 2 2 < o 00 --H in in in 00 in 00 NO 1— H 0 0 00 00 ON ON 00 00 > (ON (ON ON ( 3 N ON 00 0 ON ON u X < X < d d <— > (ON X 00 Vh 0 Vh X < to 0 (N (On (N C /0 to CO (N (N f— ^ (N (N ON 0 (N d d d- 00 m o^ o^ > o a i:^ -2 a 2 p P P P P c5 2 2 2 2 2 2 2 O) o 73 73 73 73 73 73 73 73 xi rCl xi -p -d -p -P S-I :3 :3 :3 :3 3 33 p p p P p p p 0 Oh Oh Oh Oh Oh Ph Ph Ph Ph Ph Ph Ph Ph o C a C C a P p p P P P P P 'S o fi hH d 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H 1— H QJ p- m in in p (N On p cn cn in Tt (N (N Tt o^ Tt a\ Tt (N in w m Ti- r- Tt cn cn in p 00 § cn (N in in o H H Tt o § r-- o § Tl- p in (N en Tt Tt cn (N Ti- 00 C3n 00 Tt o a\ o a\ o in 00 Tl- • mm o O in o in (N in en in H 00 Tt Tt Tt o^ (N (N (N p (N Tt C3n T— H Tt in o P 00 Tt m cn m cn cn O) p cn 00 in in in r- On o^ o^ in in 00 p d d d d d d d d d d d d d d d d d d d d d d d d d d d d w a\ a\ 00 a\ o^ a\ 00 00 00 a\ 00 a\ 00 00 00 00 00 00 OO 00 00 OO O) r- o^ p H Tt (N p OO o CTn in in (N (N (N r- o Tt o^ o C3\ o^ o p 00 in O in (N p o 00 Tt p p p (N p O P p- in (N i(— H cn in o in (N O (N 00 Tt (N (N 00 cn cn cn 00 00 § r-- OO § in r- m P (N o o in O o^ (N o in 00 o o h-H H H Tt t-H in o (N P (N (N (N cn cn cn cn (N cn 00 cn o^ o (N O o O (N o cn (N o o (N d d d d d d d d d d d d d d d d d d d d d d d d d d d d (N m m m cn cn cn (N cn cn (N cn (N cn cn cn cn cn cn cn cn cn cn cn cn cn cn cn Tt o^ o^ in o^ o^ in o^ o^ in in o^ o^ in o^ a\ in ON ON in ON ON in ON ON in ON ON in ON ON in ON ON in ON ON in ON ON in ON ON in ON in ON ON in ON ON in ON ON in ON ON in ON ON in ON ON in ON ON o in ON ON p ON P ON ON p ON ON H p P P P o^ o^ p p p p 1—5 in p p 1—5 P P 1—5 2 1—5 >5 2 1—5 o 2 1—5 o H 2 (N 2 1—5 P H 2 O 2 O cn 2 O ON ON H > o > o 2 (N > o 2 (N > o 2 > o 2 00 1— H o o Q O (N X o O 00 (N 00 O (N o o O o vq d d d d d d d d d X d d X d d d d d d d cn o o o o o o 00 o 00 O 00 o^ a\ o o o o 00 o o o o in o o in (N 00 (N m m ov m VO (N m in m m 00 o VO (N (N 00 (N 00 m 00 00 in in in VO m ov (N d- (N o (N VO O in o VO o m in 00 (N m 00 O m X t-H m H 00 VO m ov VO (N in 00 00 m (N m (N o (N (N o (N ov cn O m m m (N m m d d d d d d d d d d d d d d d d d d d d d m m cn m m m m (N m (N (N m (N m m m m m m m m d o 3 u d o d ■§ -d H > Td O s 4h o P 73 C C3 d o a c3 X o 73 c3 33 c/3 c3 Oh -a d d d d O -e d ffi d d I— ( d o d o d d o PQ d o d PQ d X) d d X o d o CIh 2 o d .3 ■ o 00 3 d < O (N 3 d •— > (OV (d B d < O (OV (N (OV d (N (OV (N (N a\ o^ o^ 03 o o d d d ov (OV ov ov (OV ov ov ov (OV ov ov (OV ov ov ov ov ov ov U U Vh d >— 5 OX) o 00 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 -o -o -o -o -o -o -o -a -a -13 O) o xi S-I 3 3 3 3 3 =5 3 3 3 0 Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh o a C C a C C C C a C c/) 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 -o -o -o -o -o -o -a -o -o 73 73 73 73 73 73 xi xi xi X) 3 3 3 3 3 3 3 3 3 :3 3 3 3 3 3 Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh Oh C C C C C C C C a C C C C a C 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 S a a o o HH Q 2 -3 fi hH o (N QJ IT) o^ X X X X H o cn O 7t o O o o o o O O IT) X o^ o^ a\ o^ t-H 7l- o\ (N X a\ (N 7l- m m o o o X o O 00 X X X X 00 00 (N in 00 r- Tj- r- (N in X m § in m m 7l- X X 7l- 7l- m T— i X 00 (N in o^ o^ (N in 7l- X in m a\ a\ OX) (N cr\ r-; r^ r^ in 'xt-_ in o o (N in 00 (N 00 00 oo 'x|- o o G A rn d d d d d d d d d cn d d d d d d d d d d d w a^ a^ o^ 00 00 00 a^ o^ a\ 00 a\ a^ o^ 1 o^ 1 00 oo o«p a\ 00 00 00 00 a\ o\ O) r^ o o in , (N o 7j- o^ 00 X o m r- Tt o 00 <3 o o^ (N r^ o^ a\ in r- 00 o o m o^ m o^ 00 in 7l- r- X (*n o r^ m X o o in r^ X o o m 7l- o^ in On X (N O o^ 00 IT) H 00 m (N m o 00 X r- (N r-H a\ Tj- Tf H m o^ Ti- Tt '■^ (N 00 r- IT) in 00 in X (N (N 7l- o^ (N 00 (N (N 00 o (N 1— H (N r- en m CO d d d d d d d d d d d d d d d d d d d d d d d d d hJ m (N (N (N (N (N m (N (N (N m m (N m (N m cn (N m m m cn (N cn m o^ o^ o^ > 0 (N 1 o^ o^ o^ > o 00 (N o^ o^ o^ o^ o o^ o^ o^ O O o^ CM CM o o o i/-\ o CM O CM CM CM CM CM o CM CM (N O O CM Sn C3 C3 o CM o CM 71 s s CM 0^ d d i— ) d d 1—5 On o^ 00 00 (N 3 •— > 00 Date Location description Latitude Longitude No. Individ. Source LOUISIANA (continued) 20 Jul 2002 between Tchefuncte River and Causeway near Mandeville 30.38997 -90.15536 1 unpub. data 23 Jul 2002 Sunset Point (2 miles from harbor). Mandeville, 30.34100 -90.09500 2 unpub. data Lake Pontchartrain C3 d d d d d d d d d d d d d d d d d d d d d d d d d d d d C3 C3 d d d d d d d d d d d d d d d d d d d d d d d d d d d 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 73 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 43 d d d d d d d d d d d d d d d d d d d d d d d d d d d d d Oh Oh Oh Oh Oh Oh Oh dn Oh Oh Oh dn dn dn dn dn dn dn dn dn dn dn dn dn dn dn dn dn dn d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d d '-H (N o o O o o O O in o O O NO O Tt Tl- en O en O O O O O O O O o o o o o o en o (N in in (N ON NO en T— 1 o o 00 o »n § in in in in in in § en o r- ON 00 Tt r-- (N en Tt en § in 00 § Tt § in o^ ON ON ON ON ON O ON en in NO in en 00 NO (N NO o en in o ON Tt ON ON o o o o o o o (N o 00 en in 00 O o 00 00 NO in ON 00 ON o o o in 00 o d d d d d d d ON d ON ON d ON d d ON ON d ON d ON ON 00 d d d d a\ d o^ 1 o^ 1 ON 1 ON 1 ON 1 ON 1 ON 1 00 1 ON 1 00 1 00 1 ON 1 00 1 ON 1 ON 1 00 1 00 1 ON 1 00 1 ON 1 00 1 00 1 00 1 ON 1 ON 1 ON 1 ON 1 00 1 ON 1 o m en (N 00 (N in en ON 00 ON o o o o o o o o NO en en Tl- NO (N 00 00 o (N o r- en O O o (N 1*^ ,-H r-H t-H (N NO Ti- en o ON O ON en o i-H (N o in o d- Tj- Ti- Tt Tt Ti- Ti- in Ti- (N r- en (N (N Tt (N OO NO NO so Ti- in (N NO Ti- m m en m m en en o en (N (N en (N en en (N (N (N (N en (N (N so en en en en (N en d d d d d d d ON d d ON d d d d d d d d d d d ON d d d d d d m m m m m en en (N en en (N en en en en en en en en en en en (N en en en en en en I (U =3 u C3 a u § ^ c« o a a O S/J cd ’§ C3 a a PlH u a ,_r ^_r ffi d D a 'o ‘o a ’o D o GO '> Oh Oh Qh ’> d D 73 D D D D 73 c/3 § C/3 C C/3 C (/3 a d cb D O 00 O cn O GO ^'d I -!= O "S c£ o3 O O o o 3 c B 23 ^ 22 3 s I l| ’S "S £ 2 _d 'o d s d d ^ D ^ d d Oh Oh ^ d "5 £ X D O D "d d c/3 o o o Oh o cd d .a d 73 o PQ .a s .a d o C3 PQ D d C3 U Dh o ”5 d o 73 D s I D d 73 o 13 bp 43 d bJO 73 .S c3 C4 (D O D -d d D 73 d C3 13 73 D 73 d o di D c3 D PQ .22 ^ 'd C) h- 1 13 o o -d 43 OO 00 -S ’B tn tn o o o^ OO o C3 ffi > D 73 d c3 (N O o (N (N (N (N CM (N (N d d d d I— ) I— ) H-5 1—5 en T^ Ti- NO (N (N cs (N cs cs cs (N (N CM rvl (N O CS o o o o o o O O O O (N O o (N O o o en en o (N (N (N bX) CM bJO (N bJO (N bX) rs bX) (N CM CL (N rs L4> O (N 3 1—5 ON bJO d < d < rs d < d < ON d < ON d < 00 (N C4 D C4 D GO D GO ON o o Vh CL < d d H-5 (N r- (N GO ON cs 00 en en en en en en en en en en O O O en o O o o o o <-4 o (N o (N cs d rs d O o CM (N o (N (N (N bX) cs bX) rs bX) d d d d d 1—5 d 1—5 3 3 1—5 3 1—5 3 1—5 d < d < d < 1—5 H-5 ON SO 1—5 en o NO cs in (N NO (N Tl- en (N cs m o o (N Oh D 00 O ON ON 00 00 00 o^ ON ON "—I s / in in in in in in c/3 ON ON ON ON ON ON tj- d d D ON ON ON ON ON ON in o^ d d o c X X X O X X X 1—5 C3 d C3 a a a 3j- a\ a 33 ON a cd 33 'vl- ON a 0^ 33 33 c 03 N a a a a a a a d D QD 33 d D QD 33 d D QD 33 d D QD 33 d D QD 33 a 1 QD 33 C3 C3 C3 C3 a a a d d D 33 a a a a a 03 a rH rH rH rH rH a rH -o -o 33 33 33 33 03 d d 33 33 33 33 33 33 33 03 03 03 03 C3 33 03 X X X X X J3 Vh D a ;h D a Vh D a C 03 C3 X J3 X X X X X O O O O O X O d d d d d 3 d o d o d d d Vh ?-H ?-H Vh 5 -h d ?-H CD CD CD CD CD CD > > > ^H CD CD CD CD CD CD CD X a a a a CD a d C d d d d P o o P o o P o o D d C d d d d d D D D D D d D d 3 d d d d Oh (Oh Oh QD d O d d d d d 00 00 00 00 00 d 00 a < < a a a a a fi hH d “ “ “ “ “ “ z (N z “ “ “ “ “ “ “ “ (N (N “ “ Z D in O (N 00 m 00 (N 00 NO CD NO (N o o 00 o cn n cn cn n in 00 ON NO 3l- (N o 00 NO NO NO NO (N in cn n cn cn cn cn ON Tj- § r- m NO o CD (N § § in § cn n cn cn cn ON o in in NO (N (N 3l- NO (N o in 00 o n oo 00 cn oo W) ON o NO 00 00 cn (N (N (N (N (N ON (N cn q q q n (N n Sh A ON d ON ON d d [d [d [d [d [d [d [d [d in [d in in in 3j-‘ [d w hQ 00 ON 00 00 1 ON 1 ON 1 ON 1 ON 1 ON 1 ON 1 ON 1 ON 1 ON 1 ON 1 ON 1 ON 1 ON 1 ON 1 ON 1 (3N 1 ON 1 C3N 1 ON 1 ON 1 D CD cn ON 00 00 cn cn n cn cn O ON 00 Tj- O oo in (N O 00 m 00 ON ON 00 NO o n cn cn n O (N cn d o in cn o in cn ON in 00 (N ON NO O NO T— 1 o n cn cn cn O in Tt r- in (N 00 NO 3l- (N 00 r- H 1— H in 00 cn n 00 in O ON '■HH NO cn (N 00 cn cn ON ON NO in Tj- o o NO in O (N in q q C3 ON ON ON ON d d in in NO NO NO NO 00 NO ON ON On ON NO hJ (N (N (N (N cn cn (N (N (N (N (N (N (N (N (N (N (N (N (N (N (N (N (N (N S a a d d PQ 3 O o ^> t: o Oh a I a m cr -S Oh O r- D > 3 o ''^ .a^ _ .^£ 'p. LIh s .a HH O t: o ^ hJ S o X) c^ tX) c c^ s ^ -o c c/3 -d CN CN ^ i ^ 0-^0 ’d' S 'd I W I c/3 c/3 HH C l-H ^ ^ H'l Vh’' rd -o c c^ c/3 O 73 c^ C c^ c^ Oh d o 00 d W) -o s tX) c ’T3 d Oh (7J C 3 tX) c^ Vh o PQ c o 03 o I ^ (T) d ^ ^ § a sp C hJ I ^ s I C3 U 3 ^ ^ 2^ d d 73 CD c/3 ^ Si HH ID -rt o3 <1) d ^a iJi 5 O o G-h o D 03 ^ O *5 ^ Shh O D c/3 . i? c rd Q ^ hd -C ^ C3 § d D ^5 O 00 IZ; CIh d o 'O r-- o^ D c3 d < HH Q Z &H &H CD (N > O Z s o n- (N n- (N S '3- O O (N (N >5 >5 o tX) r7 i:3 C3 (N cd 3 < O >— 5 1— H NO (N (N m NO ON ON ON ;h D rH Vh o ON ON s 1 m in D d n d c^ ON in (N ON ON (N ON ON ON 3l- ON ON 3l- ON D ON o 1—5 > o s ON T— H D D Z a 1—5 d d CD D c3 c3 ON in 00 in in ON ON in in in ON in ON ON ON ON in ON m r—i On ON ON 1 , ON ON ON r~\ . ■rH i-H r^ D ON ON i— H D CD CD CD o — N tX) GO 00 1 D 00 in D 00 00 D 00 00 rd D o o O in < cn D 00 O) 0 a a o o HH Q 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 O) u 73 73 73 73 73 73 73 73 73 73 -p -p -P -P -P -P -P rCl -P -P Sh 3 3 3 3 3 3 3 3 3 3 a Ph Ph Ph Ph Ph Ph Ph Ph Ph Ph 0 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 in o^ o^ +3 73 s § i5 (N 73 w X)-Q-0-C)-0 ,o ,o ,o ^3:3333^333 OhOhOhOhOhJS OhOhOh 33333'^333 33333 PQ 333 3 3 3 B 3 3 3 3 3 3 3 3 3 73 73 73 73 73 73 73 73 -P ao ao -P -P -P -P -P 3 3 3 3 3 3 3 3 Ph Ph Ph Ph Ph Ph Ph P 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 P T3 _ a> 3 . 3 m 0 (N m 00 3 - 0 0 r- m m r- 3 - (N 0 VO 00 0 r- OV OV VO 00 0 0 m m 3 - 0 m 0 m in 0 VO VO m m VO VO vo OV in (N 0 m r- 3 - in 3 - in 00 m OV VO 00 m in 00 3 - 0 § in H VO m m VO (N ov 3 - § 0 0 in in 00 m 0 00 § 0 in m ov VO 00 0 0 0 (N ov ov 3 - in VO 00 00 (N in m 00 ov in in m 00 (N in in VO in 3 - 3 - cn 3 - VO 3 - o^ cn cn (N q cn cn q q q (N (N q q q q cn rn rn rn q q q cn q q q q q q q q q q 'sd in in 3 - a\ Ov Ov Ov ov GJv Ov Ov ov ov ov q q q q q q q q q q q q q q q q q q q q q ov 1 0 00 m (N (N m <3 <3 3 - m ov m m VO (N ov 00 in 3 - cn in m in cn 0 VO VO m 0 0 0 0 VO m m Q VO 00 m 3 - (N in VO 3 - 0 00 1 — H 7—1 cn cn 3 - 'sO (N 0 00 ov 3 - 0 VO VO 00 0 0 0 i-H VO 0 00 0 in 0 00 (N 00 00 in 0 3 - t-H in cn cn in 0 H H (N H m m m m 0 0 0 3 - m 00 i-H m m in t-H (N 0 3 - m OV 3 - m m OV 00 cn cn 00 o^ VO 00 q 00 00 00 00 00 r- r- in q 00 00 00 00 00 00 00 00 00 00 00 VO 00 00 00 in 00 00 00 in 06 ov ov ov 06 vd (N (N (N (N (N (N (N (N (N (N (N (N (N (N (N (N (N (N (N (N (N 3 0 ffi 3 ffi 3 3 c/D rH c/D 3 c/D 3 q 73 c/D 3 & s 3 3 3 c/D _3 ’3 c-V P s 3 c /3 3 3 3 0-1 00 ^ I ^ I X) ^ (U CLh 33 O O 0^ ^ -I 3 3 Q c£ ^ u 3 3 b d) 3 3 PQ & o U 3 _o 3 u < 13 > 3 3 x: U > 3 C/D O ^ I O ^ ^ s •3 3 H H 3 b & ^ 3 B c/li I d) d) tj S < •3 t: :S ^ 3 Oh 3 3 PQ 3 O C/D d) 13 o d) o 3 B ’o 00 d) 3 < s _3 3 O" < 3 X 4 h o 3 3 3 O 3 bJO <£ 3 3 a I 3 -a § 10 - 3 ; s g, s -j ^ g 3^-3 §03 00 OO X _ d) ^ 2 c/3 d) B ^ 0 ^ Oh 1 ^ ffi 3 3 3 or < d) cb c/3 3 3 OO X b H Oo Vh Vh 3 3 d) d) 3 3 O U 3 3 Oh S O U 30 _3 ’3 ta d) 73 b 'p 3^3 -^ 3 ^ 3 ^ tn ^ tn O b o Oh ^ Oh Vh ^ 03 O 3 d) O d) 3 73 3 73 73 3 3 rin rin tn tn O O Oh Oh Sh Vh 3 3 d) O 3 3 73 3 3 3 3 30 3 hJ O 73 O 3 B 13 g 3 Oh B u 3 b d) p 3 Oh 3 I O 3 ffi I 3 3 . 3 3 Oh Oh ■a £ a < < a 3 d) d) j3 j3 3 t /3 C3 c/3 b 3 Oh bB § I P 3 2 3 J ^ o o >> >> o o I" ci ^ I c« O^ S =2 3 (U l 4 H o 3 3 rin s 3 3 B 3 < jy3 'o 3 _o 3 bBl ffi 3 3 O O c/3 C/D 3 d) Oh 3 3 O 3 r 3 in ov ov in ov ov in ov ov in ov ov in ov ov in ov ov in ov ov in ov ov in ov ov in ov ov in ov ov in ov OV VO ov 0 0 1— H 0 0 > > > ov (N Q-i P (N > > > (N CO 0 0 d> 0 > > > 0 0 0 0 0 d) 1 . to to 0 0 0 CO d) 0 0 0 0 0 0 ^7- 0 d) /-s b^ HH# 3 •— S (D 00 d) /H 0 0 d) Q 00 in VO Xh Xh Xh (N (N r- u Cu HH 3 - cn VO 3 - ov 0 w CN (N (N cn (N VO 00 (N VO 2 Cy ’-H (N cn CN cq o a U u ID D pq D o ba o Q O D o S QJ O X o D o X D D U u X X c 3 bO S m d B oo . X ^ X o X X ’> ’> bl) C3 a X X bH X a a a X vn X B X oo r-; CO cn t/3 X U X x X CO CO CO o G cb G a U H-» CS X < X < 2 X Ch X a> X d CD z d CD z CO "o Q d CD C3 C3 X X X CD _CD X X On o o 'o’ o o PLh z X z r- a a> Ui X cn r- cn PLh a s s CN vn X s s s cb o bX) M-179 o o o o s § A c /2 a s fl u ffi 00 N/A u ffi in u ffi 00 a CO cb 13 CO u X (N 00 s u X X c3 13 U x" D Cb D PQ GO O CD X X X CD On ’B B t>X) vn I r-- c 3 ^ u Vm 0 O to 2 c3 c3 ^ OD Pl, c3 'o ^ 1 O ^ 5.2 ^ ■ c 3 ’O o c3 c3 c3 73 O OD OD o o c3 PP PP PP CD c3 q O o c 3 Oh O u o o s pp CD o „ o . tZr 5^ o 73 o o _ , >. CO ^ pp ^ h2 o ^ O c 3 PP g (D W) O S u ^ o o pp OD (X3 1 r- 2 CD 0 P3 0 P-H 0 z Ph CD _> C3 CD 2 HM CD CD P3; CD Z c3 CO (O s (D Z Ui 0 C3 p2 B 0 bO CCS C3 c3 c/3 c3 (D c/3 0 CCS £ z 1 0 P3 CD c3 ffi 03 C/0 QD Z 0 c3 CD C3 C3 z CD 03 CD s ’B Z 03 00 P-H vm 0 C3 73 c3 C3 H 0 0 CO c3 cS >7 cd z 0 P-H 0 % 73 C3 Ph c3 0 1 »-H 0 0 'o m Z z CD C3 0 0 < CD 03 z 0 OD C3 PP w P3; 2 pp H C3 m o (On 0 0 0 > z r- 0 00 00 0 NO 0 'Ct NO S 0 r-- 3 OD PQ 3 CD O q 3 3 C/5 1 ^ .3 q g c^ '£h q 3 c/5 _3 o O < HH Q &H &H 250 pg L“^ (Table 3). Weeks Bay had the highest Chi a concentration peaking at over 200 pg L“^ at the Turkey Branch site, but also exceeding 100 pg L“^ at several other sites (Figure 2). In contrast, Chi a in Apalachicola Bay and Pensacola Bay never exceeded 20 pg L“^ and had ranges and means similar to each other (Figure 2). One common finding in all 3 systems was that Chi a tended to peak at the mid-estuarine sites on a given date (Figure 2). DIN concentrations ranged from below detection to 148 pM, exhibiting a typical spatial pattern with highest concentrations at the freshwater sites decreas- ing along the freshwater to marine estuarine gradient (Figure 3). Weeks Bay had by far the highest DIN concen- trations, with peak concentrations at the Upper Magnolia River site, ranging 94.2 to 148 pM (Figure 3). As with Chi a, Apalachicola and Pensacola Bays had similar but much lower DIN concentrations, rarely exceeding 20 pM. DIP concentrations were generally low in all estuaries, never exceeding 1 pM (Table 3), and there were no obvious DIP- salinity gradients (data not shown). Cyanobacterial abun- dance varied by over 3 orders of magnitude from 0.004 to 5.8 X 10^ L“^ and, similar to bulk Chi a, were generally most abundant at the mid-estuarine sites (Figure 4), peak- ing at salinities near 5-10 psu in Weeks Bay, 10 psu in Pensacola Bay, and 22 psu in Apalachicola Bay (Figure 5a). Similar to DIN and Chi a concentrations, mean cyanobacterial abundance was highest in Weeks Bay and lower in Apalachicola and Pensacola Bays (Table 3, Figure 4). However, in contrast with DIN, the freshwater sites had the lowest cyanobacterial abundances, usually one or 2 orders of magnitude lower than nearby estuarine sites. This pattern was most evident in Pensacola Bay (POl) and Weeks Bay (Weeks Creek, Magnolia River). At the marine sites, cyanobacteria abundances were lower than at the mid-estuarine sites, but not nearly as low as the freshwater sites. In Apalachicola Bay, only the East Bay site had high cyanobacterial abundances, averaging 2.3 X 10^ L“^ 2 to 3 times higher than the other sites. In contrast. Weeks Bay and Pensacola Bay had high cyanobacterial abundances at most estuarine sites, peaking at 5.8 X 10^ L“^ and 4.6 X 10^ L“^, respectively. Although there were only 3 sampling dates, there was a consistent temporal pattern in Weeks Bay and Pensacola Bay (Figure 4). In general, cyanobacterial abundance peaked during summer when temperatures are warmest (ca. 30 °C). In Pensacola Bay, peak abundances occurred during August, whereas, in Weeks Bay, a similar peak occurred during July (there was no August sampling in Weeks Bay). This temporal pattern was not evident in Apalachicola Bay where cyanobacterial abundances were similar on all dates; however, this may be due to inade- quate sampling earlier in the summer, as the first sampling date was not until September. In order to gauge the importance of the cyanobacteri- al component of the phytoplankton community, we con- verted cyanobacterial abundance to equivalent Chi a con- centration using a factor of 3.4 fg chi a celL^ (see Murrell and Lores 2004). Cyanobacterial Chi a was then normal- ized to the total Chi a concentration and plotted as a func- tion of salinity (Figure 5b). This analysis showed that cyanobacteria contributed a large fraction of the total Chi a, especially in the low- to mid-salinity zone of the all 3 estuaries. In Weeks Bay, for example, many values were at or near 100%, suggesting that virtually all of the phyto- 98 Mean values and ranges for salinity, DIN, DIP, Chi a, and cyanobacterial abundances during 2001. Range O (N in (N 00 ON m in ON o q .2 q q in q q oo i-H cn 4 (N (N 1 3 (N 4 2 4 in 4 in 4 (N 4 w 1— H o H O o O O 0 O 42 ON o d d d d d d d d d d d O a biD NO 00 o 00 NO in m in q q q NO q q q q q U <1^ d d d d (N d d rn ?s Range 1 O) r-; (N 1 cn .6-6.2 q 00 1 q q in H 1 q in NO 1— H 1 O) q in t-H 1 q q 00 in ON 7 q q rn in 7 q q 1 ON s (N 1— H 1— H 1— H (N d u W) 3 fl a ij ON q q q 'Ol- (N q q q q ON NO cn NO (N 1— H d On in d in in in (N (N (N 00 (N m ON ON in m in o O a> o ob 3 W) o < C4 O 00 o O > o ob 3 H- 5 Oh O > o tb O (N o o NO m ON GO r- 4 (N 00 (N 'o o s 3 Lm o o c/3 CQ =s rin d c/3 44 o >N VI Qh a <0 03 C3 < m Oh m m Murrell and Callrey ^JliJv HAug □ Sept ^ Oct □Nov Figure. 2. Chi a concentration at all sites and dates sampled during the study: a) Apalachicola Bay, FL; b) Pensacola Bay, FL; c) Weeks Bay, AL (note different scaling). The sites were arranged in order of increasing mean salinity for each system as list- ed in Table 2. plankton was comprised of cyanobacteria. In the other 2 systems, this fraction was not usually so high, but fre- quently exceeded 50%. Interestingly, when averaged across all sites and dates, the percentage of cyanobacterial Chi a was similar in all 3 systems; 31% for Apalachicola Bay, 39% for Pensacola Bay, and 36% for Weeks Bay. However, these global means can be considered biased low because the freshwater sites are clearly unsuitable habitat for cyanobacteria, where they contribute virtually 0% to total Chi a. Including only estuarine sites (mean salinity > 2, Table 2), the mean cyanobacterial contribution to total Chi a increased to 32%, 47% and 43%, respectively. Discussion The physical settings of the 3 estuarine systems (Table 1) have important similarities (e.g., rainfall, water depth) and differences (e.g., estuarine area, watershed area, freshwater flow) which help provide a context for interpreting the biological and chemical data. Apalachicola Bay is the largest system, with the largest watershed and is least impacted by anthropogenic nutrient inputs, as indicat- ed by the low mean DIN at the freshwater source (mean 17.4 pM). Bay wide mean Chi a and cyanobacterial con- centrations were lower than those of the other 2 estuaries. Apalachicola Bay has a strong marine influence and a rel- 100 Cyanobacteria in Gulf of Mexico estuaries ^ July ■ Aug □ Sept g Oct □ Nov a) Apalachicola Bay b) Pensacola Bay c) Weeks Bay Figure 3. Dissolved inorganic nitrogen (DIN) concentration at all sites and dates sampled during the study: a) Apalachicola Bay, FL; b) Pensacola Bay, FL; c) Weeks Bay, AL (note different scaling). The sites were arranged in order of increasing mean salin- ity for each system as listed in Table 2. atively short residence time (6 d), explaining the high mean salinity (24.2). The rapid Gulf exchange probably acts to dilute nutrient, Chi a, and cyanobacterial concentra- tions. Pensacola Bay is intermediate in size, with moderate anthropogenic impacts from the watershed. Exchange with the GOM is narrowly constricted at Pensacola Pass, con- tributing to its relatively long residence time (25 d) and a lower mean salinity (12.9) than Apalachicola Bay. At the Escambia River site (POl) DIN averaged 12.5 pM, some- what lower than the Apalachicola River mean; however, non-riverine sources of DIN (e.g. sewage treatment plants, urban storm-water runoff) are relatively more important in Pensacola Bay, given the relatively high human population (ca. 300,000 people) surrounding the bay. This may in part explain the higher bay-wide mean DIN, Chi a, and cyanobacterial concentrations in Pensacola Bay compared to Apalachicola Bay. Weeks Bay has a much smaller watershed and estuar- ine area, nearly 2 orders of magnitude smaller than Apalachicola Bay or Pensacola Bay, and on the marine end exchanges with Mobile Bay estuary rather than the GOM proper, explaining the low mean salinity (5.7) we observed. The rate of water exchange between the 2 bays is strongly dependent on river discharge and wind forcing (Schroeder et al. 1990), but the mean freshwater residence 101 Murrell and Callrey ^ July ■ Aug □ Sept g Oct Nov Figure 4. Cyanobacterial abundance at all sites and dates sampled during the study: a) Apalachicola Bay, FL; b) Pensacola Bay, FL; c) Weeks Bay, AL. Within each system, the sites were arranged in order of increasing mean salinity as listed in Table 2. time is short (6 d) similar to Apalachicola Bay. It has high anthropogenic nutrient loading as evidenced by high fresh- water DIN concentrations averaging 51 pM in the Fish River and 127 pM in the Magnolia River. It also has the highest bay wide mean Chi a concentrations and cyanobac- terial abundances. Mean cyanobacterial abundances were about 350% higher than Apalachicola Bay and 50% high- er than Pensacola Bay. In this study, peak cyanobacterial abundances ranged from about 3 X 10^ (Apalachicola Bay) to nearly 6 X 10^ Lr^ (Weeks Bay) and are among the highest reported in the literature (Table 4). Cyanobacteria have been enu- merated in a wide range of estuarine and near-coastal envi- ronments, ranging from tropical (e.g., Phlips et al. 1999) to northern latitude systems (e.g., Kuosa 1988). Cyanobacteria abundances in these systems vary consider- ably, but highest abundances always tend to occur during summer, and lower latitude systems tend to have higher peak abundances than higher latitude systems. Because the time frame of this study was restricted to one summer-fall period, we acknowledge that the results may not be representative of longer-term patterns. As men- tioned earlier, freshwater flows were below long-term averages, which likely caused higher salinities and lower water column stratification than expected to occur during more normal flow conditions. While interannual variation in such factors likely affect the location and extent of high cyanobacterial abundances, it seems clear from longer- 102 Cyanobacteria in Gulf of Mexico estuaries Figure 5. Distribution of cyanobacteria as a function of salinity: a) cyanobacterial abundance, and b) cyanobacterial percent' age of bulk Chi a. The 3 estuaries are distinguished by different plot symbols. term datasets (e.g., Marshall and Nesius 1996, Phlips et al. 1999, Murrell and Lores 2004) that high cyanobacterial abundances are a common summer-time feature of estuar- ies. It is further clear from this study that cyanobacteria can be an important component of the phytoplankton com- munity in these GOM estuaries, despite considerable vari- ability in hydrology and anthropogenic impacts. Assuming a nominal cellular Chi a content, cyanobacteria contribute from 30 to 50% of the total Chi a in all 3 estuarine systems. This percentage agrees well with the 2+ year average of 43% reported for Pensacola Bay (Murrell and Lores 2004), and is among the highest reported in the literature. For example, in San Francisco Bay, cyanobacteria mean 15% (maximum 38%) of total Chi a (Ning et al. 2000). In the Neuse River estuary, cyanobacteria represented 18% of total Chi a based on HPLC pigment analysis (Pinckney et al. 1998). In the York River estuary, pico-phytoplankton comprised 7% of Chi a over an annual cycle, peaking at 14% during summer (Ray et al. 1989). In the Kiel Bight, cyanobacteria contributed up to 52% of the total Chi a dur- ing summer (Jochem 1988), while in Southhampton estu- ary cyanobacteria contributed 10% or less to bulk Chi a (Iriarte and Purdie 1994). It should be noted that normaliz- ing cyanobacteria to Chi a likely underestimates their true contribution to phytoplankton carbon biomass and produc- tivity, given that cyanobacteria have relatively low chloro- phyll content per unit of carbon compared to eukaryotic algae, particularly diatoms (MacIntyre et al. 2002). One pattern noted by Iriarte and Purdie (1994) was that the relative importance of picoplankton appears to diminish with increasing trophic state, ultimately con- 103 Murrell and Callrey TABLE 4 Peak abundances of cyanobacteria reported from various estuaries and inland seas. When available, temperature and salinity data at the time of collection are included and the month of the year the sample was collected. Location Temp °C Salinity psu Peak Abundance (cells X lO^L-i) Month Reference St. Lawrence River (Canada) 21 0.1 17 Jun Bertrand and Vincentl994 North Inlet (SC, USA) NA NA 55 Sep Lewitus et al. 1998 Southampton (UK) 19-20 34 130 Jul Iriarte and Purdie 1994 Yangtze River (China) 25-30 200 Jul Vaulot and Xiuren 1988 Long Island Sound (NY, USA) 24.3 NA 232 Aug Carpenter and Campbell 1988 San Francisco Bay (CA, USA) 22 20 234 July Ning et al.2000 Gulf of Finland 12-13 6 243 Jun Kuosa 1988 Kiel Bight (Baltic Sea) 22 14 260 Jul- Aug Jochem 1988 York River Estuary (VA, USA) 28 22 750 Sep Ray et al. 1989 Chesapeake Bay (VA, USA) 26 NA 920 Jul Affronti and Marshall 1994 Chesapeake (MD & VA, USA) NA NA >2000 Jul Marshall and Nesiusl996 Apalachicola Bay (FL, USA) 25 24 3100 Sep This Study Pensacola Bay (FL, USA) 29 11 4600 Aug Murrell and Lores 2004, This Study Weeks Bay (AL, USA) 30 6 5800 Jul This Study Florida Bay (FL, USA) NA 35 >5000 Oct Phlips et al. 1999 Mississippi River Plume (USA) NA 8 >5000 Jul Dortch 1998 tributing < 5% when Chi a concentrations exceed 5 pg In this study, cyanobacteria appeared to dominate the phy- toplankton well beyond this 5 pg threshold. The estu- arine sites with the smallest cyanobacterial contribution (excluding freshwater sites) were the highly eutrophic sites (e.g. Weeks Bay) where total Chi a concentrations exceed- ed 100 pg L“^. Instead, phytoplankton at these sites were comprised of small diatoms (up to 6 X 10^ L“^) and cryp- tophytes (up to 2.6 X 10^ L“^). However, such highly eutrophic conditions are relatively rare in COM estuaries, and seasonal maxima for Chi a more typically range from 10 to 20 pg (Pennock et al. 1999). In this range, the potential for cyanobacteria to dominate the phytoplankton is quite likely, given that an abundance of 5 X 10^ cor- responds to 17 pg Lr^ Chi a (assuming 3.4 fg Chi a cell“^). Therefore, data from this and related studies (e.g., Phlips et al. 1999, Murrell and Lores 2004) appear to challenge the generalized pattern observed by Iriarte and Purdie (1994), showing that cyanobacteria can be dominant in COM estu- aries and can represent nearly 100% of the Chi a, especial- ly during summer. While there are several reports of cyanobacterial abundances in estuaries, cyanobacterial growth rates and productivity are more rarely quantified. However, studies conducted in several estuaries, including Chesapeake Bay (Affronti and Marshall 1994), Long Island Sound (Carpenter and Campbell 1988), the South China Sea (Agawin et al. 2003), and Santa Rosa Sound (Juhl and Murrell in press) have consistently found that peak specif- ic growth rates range from 1 to 1.5 d~^ (1.4 to 2.2 divisions d“^). One consistent finding in these and related studies is a strong temperature-dependence on cyanobacterial growth, being repeatedly noted in estuarine (Carpenter and Campbell 1988, Ray et al. 1989, Iriarte and Purdie 1994, Juhl and Murrell in press) and oceanic environments (Li 1998). Based on these observations, it is clear that estuar- ine cyanobacteria actively grow during warm periods and significantly contribute to bulk productivity. Furthermore, given their characteristically low chlorophyll content rela- tive to carbon (MacIntyre et al. 2002), cyanobacterial con- tribution to bulk phytoplankton productivity probably exceeds their contribution to bulk Chi a. Thus, cyanobac- teria appear to be major mediators of carbon flow in sub- tropical estuarine systems and deserve further study to bet- ter quantify their role in estuarine productivity. The size structure of the phytoplankton community has a profound influence on the pathways by which organ- ic matter is transferred through aquatic food webs. Perhaps most importantly, cyanobacteria in the 1 to 2 pm size range cannot be directly consumed by mesozooplankton and demersal fish species. For example. Nival and Nival (1976) found that even naupliar stages of the ubiquitous genus Acartia was unable to efficiently collect and consume par- ticles less than 3 pm in size. Similarly, Durbin and Durbin 104 Cyanobacteria in Gulf of Mexico estuaries (1975) found that the Atlantic menhaden (Brevoortia tyrannus), a major phytoplanktivorous fish in estuaries, was unable to consume phytoplankton less than 13-16 pm in size. So the route by which cyanobacteria become avail- able to higher trophic levels requires one or more interme- diate trophic steps (i.e. the microzooplankton), with respi- ratory losses of carbon and energy at each step. The exis- tence of such trophic linkages has been demonstrated, in particular between cyanobacteria and microzooplankton (Caron et al. 1991, Ayukai 1992, Lessard and Murrell 1998, Juhl and Murrell in press), and between microzoo- plankton and mesozooplankton (Lonsdale et al. 1996, Sipura et al. 2003). However, the inefficiency of such indi- rect pathways, when compared to more direct pathways, constrains the degree to which cyanobacteria can ultimate- ly support production of top predators. In summary, this study found high abundances of chroococcoid cyanobacteria in 3 estuaries along the north- eastern GOM. Cyanobacterial abundances peaked in the oligohaline reach of each system and appeared to positive- ly covary with the degree of eutrophication. While cyanobacteria have long been known to play a dominant role in oceanic environments, their role in estuaries is not as well understood. 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Parsons. 1972. A practical manual for seawater analysis. Eisheries Research Board of Canada Bulletin Number 167, Ottawa, Canada. Utermol H. 1958. Zur Vervollkommnung der quantitativen Phytoplankton-Methodik. Mitt, int Verein. Limnol. 9: 1-38. Vaulot, D. and N. Xiuren. 1988. Abundance and celluar charac- teristics of marine Synechococcus spp. in the dilution zone of the Chanjiang (Yangtze River, China). Continental Shelf Research 8:1171-1186. 106 Gulf and Caribbean Research Volume 17 Issue 1 January 2005 Ecology of the Mayan Cichlid; Cichlasoma urophthalmus Giinther, in the Alvarado Lagoonal System^ Veracruz^ Mexico Rafael Chavez-Lopez Universidad Nacional Autonoma de Mexico Mark S. Peterson University of Southern Mississippi^ mark.peterson(®usm.edu Nancy J. Brown-Peterson University of Southern Mississippi nancy.brown-peterson(® usm.edu Ana Adaka Morales-Gomez Universidad Nacional Autonoma de Mexico Jonathan Franco-Lopez Universidad Nacional Autonoma de Mexico DOI; 10.18785/gcr.l701.13 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Chavez-Lopez, R., M. S. Peterson, N. J. Brown-Peterson, A. Morales-Gomez and J. Franco-Lopez. 2005. Ecology of the Mayan Cichlid, Cichlasoma urophthalmus Gunther, in the Alvarado Lagoonal System, Veracruz, Mexico. Gulf and Caribbean Research 17 (l): 123-131. Retrieved from http://aquila.usm.edu/gcr/voll7/issl/13 This Article is brought to you for free and open access by The Aquila Digital Community It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf and Caribbean Research Vol 17, 123-131, 2005 Manuscript received July 18, 2004; accepted September 20, 2004 ECOLOGY OF THE MAYAN CICHLID, CICHLASOMA UROPHTHALMUS GUNTHER, IN THE ALVARADO LAGOONAL SYSTEM, VERACRUZ, MEXICO Rafael Chavez-Lopez, Mark S. Peterson^, Nancy J. Brown-Peterson^, Ana Adalia Morales-Gomez, and Jonathan Franco-Lopez Laboratorio de Ecologia, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autonoma de Mexico, Av. de los Barrios No 1, Los Reyes Iztacala, Tlalnepantla, Mexico C.P 54090 A.P. Mexico ^Department of Coastal Sciences, The University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, Mississippi 39564 USA ABSTRACT The Mayan cichlid, Cichlasoma urophthalmus, has a wide distribution in southeastern Mexico where it inhabits rivers and coastal lagoons. In the Alvarado lagoonal system, Veracruz, it is distributed towards the north in Camaronera Lagoon. The Mayan cichlid shows an affinity for oligohaline to mesohaline sites with submerged vegetation, well-oxygenated, deep, and transparent water. The major abundance and biomass of this species was obtained during December to February. The diet of Mayan cichlids consists principally of plant detrital material and algae. Length-frequency distribution shows 2 size classes during both the dry and rainy seasons, corresponding to reproductive fish and young of the year; during the nortes season there is only one modal size class of fish between 60-100 mm SL. Individuals with developed gonads are found throughout the year, although most reproductive adults are found between April and December. The highest Gonadosomatic Index (GSI) values coincided with the peak in reproductive activity between May and July. The fecundity ranged from 1,556-3,348 eggs/female, and there was no relationship between female size and fecundity. RESUMEN El ciclido maya, Cichlasoma urophthalmus, tiene una distribucidn amplia en el sureste de Mexico, donde habita rios y lagunas costeras. En el sistema lagunar de Alvarado, Veracruz, esta especie se distribuye hacia el norte prin- cipalmente en la Laguna Camaronera. Esta especie muestra afinidad por sitios oligohalinos y mesohalinos con veg- etacion sumergida, bien oxigenados, profundos y de aguas transparentes. La mayor abundancia y biomasa de C. uroph- thalmus fue obtenida durante Diciembre a Eebrero. La dieta del ciclido maya consistio principalmente de detritus veg- etal y algas. La distiibucion firecuencia-longitud mostro dos clases de talla durante las temporadas de secas y Iluvias, correspondientes a individuos reproductores y menores de un ano; durante la temporada de nortes se encontro solo una clase de talla modal entre 60-100 mm LS. Los individuos con gonadas desarrolladas se encontraron a lo largo del ano, aunque los adultos mas reproductivos se encontraron entre Abril y Diciembre. El valor mas alto del fndice Gonadosomatico (IGS) coincidid con el pico de actividad reproductiva entre Mayo y Julio. La fecundidad se registrd entre 1,556-3,348 huevos/hembra y no hubo relacidn entre la talla de las hembras y su fecundidad. Introduction The family Cichlidae is of freshwater origin with about 1300+ species worldwide (Nelson 1994). Members of this family are notorious for their capacity to colonize diverse habitats such as rivers, estuaries, lakes and coastal lagoons, representing a notable adaptation to a wide range of physical, chemical and biological environmental vari- ables. The genus Cichlasoma comprises 118 species from the New World (Alvarez del Villar 1970, Astorqui 1971, Kullander 1983, 2004). At least 39 species are found in Mexico, where Cichlasoma is the most diverse genus of the freshwater ichthyofauna (Alvarez del Villar 1970). The Mayan cichlid, Cichlasoma urophthalmus, occurs in fresh and brackish waters of the Atlantic watersheds from the Rio Coatzacoalcos basin southward through Mexico, including the Yucatan Peninsula and Isla Mujeres, into Belize, Guatemala, Honduras and Nicaragua (Miller 1966, Martmez-Palacios and Ross 1992, Greenfield and Thomerson 1997). The Mayan cichlid has been recorded in the State of Veracruz in the southern Gulf of Mexico (GOM) in the Panuco, Sarabia, Chachalacas, Papaloapan, Coatzacoalcos, and Achotal Rivers. In the Alvarado lagoonal system, 3 genera and at least 7 species of cichlids have been report- ed, with the Mayan cichlid being the species with highest abundance and greatest ecological importance among the freshwater species of the system (Chavez-Lopez 1998). Mayan cichlids have been reported in river-lagoonal sys- tems associated with Terminos Lagoon, Campeche (Amezcua-Linares and Yanez-Arancibia 1980). They have also been reported from the Champoton River basin, Campeche, the Grijalva-Usumacinta River basin. Tabasco, the Yucatan Peninsula and Isla Mujeres in Quintana Roo (Miller 1966, Resendez-Medina 1981, Caso-Chavez et al. 1986, Martmez-Palacios 1987), and on barrier reefs in Belize (Greenfield and Thomerson 1997). In Mexico, the Mayan cichlid is exploited commer- cially in the artesanal fishery and has a potential for aqua- culture in freshwater areas (Miller 1966, Martmez- 123 ChAvez-Lopez et al. Camaronera Lagoon ^ ^Buen Pais Alvarado Lagoon Alvarado 95°42'W 18°52 N — GULF OF MEXICO 0 .25 1 2 3 km Figure 1. Sampling stations during June 2000-July 2001 in the Alvarado lagoonal system, Veracruz, Mexico. Inset map shows approximate geographic location of the study area. Palacios and Ross 1992, Ross and Beveridge 1995). In the local markets, it has been preferred over introduced species such as tilapias, and the price was 20-40% higher than that for introduced species in Campeche (Resendez-Medina 1981), where this species has been sold along with marine species. It has been shown that the Mayan cichlid is extremely adaptable throughout its range and that aspects of its life history vary depending on environmental conditions; for example, see Loftus (1987), Martmez-Palacios et al. (1990), Martmez-Palacios and Ross (1992), Faunce and Lorenz (2000), Faunce et al. (2002), and Bergmann and Motta (2004). The purpose of the present study is to pro- vide additional information on the biology and reproduc- tion of Mayan cichlids in the Alvarado lagoonal system in Veracruz, Mexico. Materials and Methods Field collections and processing of specimens Mayan cichlids were collected on 12 dates from June 2000 to July 2001 at 12 stations in the Alvarado lagoonal system, Veracruz, Mexico (Figure 1). Physicochemical data taken at each station included depth (cm), Secchi transparency (cm), salinity (psu), temperature (°C), dis- solved oxygen (mg/1), and turbidity (NTU); percent sub- merged aquatic vegetation (SAV) cover was estimated visually. For analysis, monthly collections were divided into seasons following Raz-Gusman et al. (1992), where the dry season was March through June, the rainy season was July through October, and the nortes season was November through February. Fish were captured at each station using a single haul of a 30 m long x 2 m high seine constructed with 6.35 mm mesh. Total area sampled with each seine haul was 756.25 m^. Fish were fixed in 10% buffered formalin and also injected in the abdominal cavity in the field to retard the digestive process. Fish were washed in fresh water after one week in formalin and then stored in 70% ethanol. Species identification followed Alvarez del Villar (1970) and Resendez-Medina (1981). Each fish was measured to the nearest mm standard length (SL), weighed (WW) to the nearest g, and the gonads were removed and weighed to the nearest 0.1 g. Seasonal feeding of Mayan cichlids was determined by analyzing the stomach contents of 35 fish from each season. Stomach contents were separated to the lowest taxonomic level possible, weighed (0.0 Ig) and analyzed according to the gravimetric method (Hyslop 1980). Gonadal maturity classes were established by extract- 124 Ecology of the Mayan cichlid ing a 1 mm thick portion of the ovaries or testes. Semi-per- manent preparations were examined microscopically to determine the class of gonadal development following Murphy and Taylor (1990). The Gonadosomatic Index (GSI) was determined using the formula GSI = [gonad weight/(total wet weight -gonad weight)/100]. The total number of vitellogenic oocytes (> 0.42 L x 0.30 W mm) in the ovaries of mature females (87 mm-146 mm SL, 28.6-66.7 g) were counted to estimate fecundity. Statistical Analysis The relationships between SL and WW of male and female Mayan cichlids and between fecundity and female SL and weight were examined using linear regression analyses. A regression of GSI vs. body weight was used to verify that GSI was an appropriate index of spawning pre- paredness. The GSI data were arc sine transformed and then compared by gender across months with ANOVA. If a significant F-value was determined, pairwise Sidak tests were used to separate mean values. A Mann- Whitney U- test was used to compare each of seven physicochemical variables between stations with and without Mayan cich- lids. Diet was compared among seasons using the Bray- Curtis similarity coefficient C^, with 0 = most dissimilar diets and 1 = identical diets (Marshall and Elliott 1997). Differences in length-frequency distributions among sea- sons were compared with pairwise Kolgomorov-Smimov 2- sample Chi-square tests. The relationship between the physicochemical vari- ables and Mayan cichlid abundance was also examined using Principal Component Analysis (PCA) in a 2 step procedure (Peterson and VanderKooy 1997). Lirst, the sta- tions were ordered based on the seven physicochemical variables with PCA of the correlation matrix, with varimax rotation to maximize the loading results. A Scree Test was used to determine the number of components, and stan- dardized scores of the factors were plotted for each sta- tion/month period against the meaningful components. Second, these station/month coordinates were coupled with the abundance of the Mayan cichlid for that specific collection station. Any variable with a correlation > 0.50 was considered when interpreting a component. All calcu- lations were made using SPSS software (Versions 10.0 or 11.5, Chicago, IL) and the results were considered signifi- cant if P < 0.05. Results Abundance Mayan cichlids were captured in 59 of 128 collections (46.1%) from the 12 stations in the Alvarado lagoonal sys- tem. The frequency of capture was similar among the sta- tions except for the Blanco River station (# 4), where the Mayan cichlid was taken during only 4 of 12 collections, and in the estuarine zone of Papaloapan River (stations 1-3) where the species was not collected. Adult Mayan cichlids ranged from 87 to 146 mm SL and had the greatest abundance in Camaronera Lagoon {n = 672, representing 52.7% of the total fish caught) and in the Aneas, Arbolillo, and Buen Pais stations (# 6,7, 8, 9) on the internal margin of the barrier separating the lagoon from the ocean. Abundance was greatest between November to Lebruary (nortes season) and lowest in April. Mayan cichlids were most abundant at stations containing SAV (Table 1); such as stations 10 and 11 in Camaronera Lagoon {n = 639, 49.4%), stations 8 and 9 in Buen Pais Lagoon {n = 200, 15.2%), and at the Arbolillo station (# 7) in Alvarado Lagoon (n = 216, 16.4%). Habitat Relationships The Mayan cichlid showed affinity for mesohaline stations, which were most common during the nortes and dry seasons and least common in the low salinity rainy sea- TABLE 1 Abundance of Cichlasoma urophthalmus expressed as a percentage of the individuals collected, as percentage in sta- tions with < 50% coverage with submerged aquatic vegetation (SAV), as percentage in stations with about 50% cov- erage with SAV, and as a percentage in stations with > 50% coverage with SAV. Sampling stations correspond to stations on Figure 1. Sampling Stations 12 11 10 9 8 7 5 6 4 2 3 1 TOTAL Overall abundance 3.3 32.4 17.0 15.2 7.4 16.4 0.5 6.3 1.5 100.0 Stations with SAV < 50% 3.3 0.5 15.4 0.4 4.3 1.5 25.4 SAV = 50% 0.8 16.9 1.2 18.9 SAV > 50% 31.6 0.1 15.2 6.9 1.0 0.1 0.8 55.7 125 ChAvez-Lopez et al. TABLE 2 Comparison of physicochemical factors (x ± s) between habitats with with and without Cichlasoma urophthalmus. Significant difference* (P < 0.05) determined by a Mann-Whitney U test. Parameter All stations Stations with C. urophthalmus Stations without C. urophthalmus Submerged Vegetation (%)* 41.35 + 34.47 57.24 + 30.59 30.12 + 32.74 Depth (cm) 99.11 + 82.90 83.36 + 30.96 110.25 + 104.00 Secchi transparency (cm) 43.9 + 21.93 45.11 + 16.35 43.05 + 25.22 Salinity (psu)* 5.72 + 5.70 7.13 + 5.32 4.72 + 5.79 Dissolved Oxygen (mg/1)* 9.39 + 1.76 9.72+ 1.70 9.16 + 1.77 Temperature (°C) 27.8 + 2.92 27.96 + 2.92 27.7 + 2.94 Turbidity (NTU) 17.35 + 14.86 15.63 + 10.63 18.6 + 17.20 son. Stations with Mayan cichlids exhibited greater SAV (Z = 4.42, P < 0.001), higher salinity (Z= 3.16, P < 0.001), and slightly higher dissolved oxygen (Z = 1.78, P = 0.076) than stations without Mayan cichlids (Table 2). There were no differences among the other variables measured (all P > 0.05). The SAV was composed mainly of Ruppia maritima with various percentages of the algae Gracillaria verru- cosa and Rhizoclonium hieroglyphicum in Camaronera and Buen Pais Lagoons; other stations with SAV had only beds of R. maritima. There were no statistically significant dif- ferences in temperature, depth, transparency, and turbidity between stations where Mayan cichlids were present vs absent {P > 0.05; Table 2), but Mayan cichlids tended to occur at shallower and less turbid stations (Table 2). The PCA analysis extracted 3 axes that accounted for 66.26% of the total variation in the physicochemical data (Table 3). The first component represents transparency (+), salinity (+), dissolved oxygen (+) and turbidity (-). The second component represents SAV (-) and depth (-^), and TABLE 3 Physicochemical variables correlated with the 3 princi- pal components with eigenvalues > 1. The percent of variance explained by each component is in parenthe- sis. Variables with correlations > 0.50 are used in iden- tifying the components. PC-I PC-II PC-III (30.15%) (20.07%) (16.04%) Depth (cm) 0.084 0.858 0.121 Submerged Vegetation (%) 0.185 - 0.660 0.376 Secchi transparency (cm) 0.683 0.414 0.191 Salinity (psu) 0.737 -0.192 0.008 Dissolved Oxygen (mg/1) 0.688 - 0.093 -0.350 Temperature (°C) 0.018 - 0.039 0.902 Turbidity (NTU) -0.753 - 0.067 -0.155 the third component represents water temperature (+). The analysis indicates that stations of shallow depth, greater SAV {Ruppia maritima) cover, high salinity, high dis- solved oxygen, high transparency, and low turbidity had the greatest numbers of Mayan cichlid captured (Figure 2). These stations were located in Camaronera Lagoon, usual- ly during the nortes and dry seasons. Size Distribution Length-frequency histograms were constructed for each season (Figure 3). There were clear bimodal size dis- tributions for the rainy season (20-40 mm and 101-120 mm SL) as well as the dry season (1-40 mm SL and 81-120 mm SL), indicating numerous small Mayan cich- lids. In contrast, the highest frequencies in the nortes sea- son corresponded to 60-100 mm and 120-160 mm SL, with no small fish being collected. Comparison of SL size distributions among seasons, pooled by gender, indicated that there was no significant difference between dry and rainy seasons (Z = 1.322, P = 0.061) or between rainy and nortes seasons (Z = 0.685, P = 0.737). However, the dry and nortes season SL size distributions were different (Z = 1.958, P = 0.001). Log^Q SL vs logjQ WW for all females was signifi- cant (F = 1600.59, r = 0.94, P < 0.001, n = 210) and explained by logjg WW = -1.460 + 2.984 logjg SL. For males, logjqSL vs log^g WW was significant {F = 1938.99, r = 0.96, P < 0.001, n = 168), and explained by log^o WW = -1.240 + 2.752 log^q SL. Diet The Mayan cichlid was predominately herbivorous in the Alvarado lagoonal system (Table 4), with a total of 19 food types identified. All fish had plant material in the stomach, and the percentages varied by season from a low of 74.41% in the dry season to a high of 98.3% in the 126 Ecology of the Mayan cichlid Figure 2. Three-dimensional plot of the stardardized factor scores for the stations and months of collection and the abun- dance of Cichlasoma urophthalmus arranged on principal components I and II based on seven physicochemical vari- ables. Black lollypops are where Mayan cichlids were collect- ed, whereas gray lollypops are where no Mayan cichlids were collected. nortes season. Mayan cichlids supplemented its herbivo- rous diet with 18 other food types ( 2 . 12 % of the diet) in the rainy season, 4 other food types (1.83% of the diet) in the nortes season, and 6 other food items (26.6% of the diet) in the dry season. The dry season diet was unique in that it was composed of a number of animal taxa, particularly mollusks (20.1%), crustaceans (3.75%) and fish scales (2.07%). The diets of Mayan cichlid were most similar between the rainy and nortes seasons (C^ = 0.9816), There was reduced diet similarity between the rainy and dry sea- sons (C^ = 0.6716) and between the nortes and dry seasons (q = 0.6705). Reproduction Males, females, and juvenile Mayan cichlids were found in all collections in the Alvarado lagoonal system. Overall, the sex ratio of mature individuals was 1.16:1 (female: male). Gonadal recrudescence was first observed in individuals >100 mm SL in April, although individuals as small as 60 mm SL showed gonadal development in July. A comparison of GSI and gonad-free wet weight for females (r^ = 0.107, P < 0.001, n = 314) and males (r^ = 0.068, P < 0.001, n = 247) showed that while there is a sig- nificant, positive relationship between GSI and body weight, GSI explains < 10.7% of the variation in weight. Thus, GSI can be used as an index of spawning prepared- ness for this species. Female GSI varied significantly across sampling dates (Fjj 314 = 12.177, P < 0.001). The GSI indicates maximal ovarian development from May-July, with a GSI peak in May (Figure 4). Elevated GSI values were also seen in June-July 2000, verifying that maximal female reproductive activity occurs at the end of the dry season (May-June). However, there was a small peak in female GSI in December. The highest GSI values in May and June corresponded to females 120-160 mm SL. In contrast, male GSI values were significantly different over time (Fj^ 247 “ 3.062, P < 0.001) and showed much greater variability over the season than did those of females (Figure 4). Male GSI peaks occured in May-July in both years and in January 2001, similar to peaks seen in females. The large variation in GSI most likely indicates that individuals were in all stages of gonadal development each month, suggesting a protracted reproductive season. During all months, individuals with undifferentiated and immature or regressed (stage I) ovaries were collected, and these individuals made up the majority of the females collected (Figure 5). Fish with ovaries in stages II and III were captured from May-July and December-February, while reproductive individuals (stage IV) were captured from May-July and December, with the greatest percent- ages found in June and July in both 2000 and 2001 (Figure 5). Females ranging from 87-145 mm SL had fecundity Figure 3. Size distribution of Cichlasoma urophthalmus by season in the Alvarado lagoonal system, Veracruz, Mexico. Dry season was March through June; the rainy season was July through October; and the nortes season was November through February. 127 ChAvez-Lopez et al. TABLE 4 Seasonal diet composition (% weight) of Cichlasoma urophthalmus in Alvarado lagoonal System. Food items Rainy season Nortes season Dry season Plant organic matter 97.28 98.17 67.16 Fish scales 0.62 0.54 2.07 Algae 0.58 0 0.48 Tanaidacea 0.57 0 0 Ruppia maritima 0.48 0.20 5.77 Annelids 0.13 0 0 Crustacea 0.10 0.084 3.75 Insects 0.074 0 0.67 Nematodes 0.06 0 0 Molluscs 0.048 0.99 20.10 Animal organic matter 0.016 0 0 Hydrobiidae 0.007 0 0 Amphipoda 0.005 0 0 Isopoda 0.002 0 0 Diptera 0.001 0 0 Fish eggs 0.001 0 0 Acari 0.0002 0 0 Fisaria sp. 0.0001 0 0 Cladocera 0.0001 0 0 values from 1,556 to 3,348 eggs/female. There was no cor- relation between fecundity and SL of females (Fecundity = 1,916.92 + 2.780 SL; r = 0.0835, n = 14, P = 0.74), as small females often had a greater number of oocytes com- pared with large females. Discussion Mayan cichlids were closely associated with habitat characterized by SAV and salinities between 3 and 13 psu in the Alvarado lagoonal system. This explains why the majority of the Mayan cichlids collected were taken in the nortes season and greater abundance was observed in Camaronera and Buen Pais Lagoons. Mayan cichlids were absent from the three Papaloapan River stations that have zero or low salinity throughout the year. The results of the present study agree with Caso-Chavez et al. (1986), who reported a greater number of Mayan cichlids in zones influenced by the ocean and with the presence of seagrass in Terminos Lagoon, Mexico. Mayan cichlids are also reported to have the greatest abundance in salinities up to 25 psu in the Mexican Caribbean (Martmez-Palacios and Ross 1992) and Florida (Faunce and Lorenz 2000). In fact, water temperature and salinity are not likely to limit their range in non-native habitat types in south Florida except in really cold winters, because at 25 °C, salinity tolerance is 2000 2001 Month Figure 4. Plot of the gonadosomatic index (GSI; x ± s^) by month of female (n = 314) and male (n = 247) Cichlasoma urophthalmus from the Alvarado lagoonal system, Veracruz, Mexico. No collections were made in August and October 2000. >37 psu (Stauffer and Boltz 1994). There were 2 size class distributions of the Mayan cichlid documented in the Alvarado lagoonal system. During the nortes season, mainly pre-adults and adults (61-160 mm SL) were captured, as has been reported in other Mexican locations (Caso-Chavez et al. 1986, Martmez-Palacios and Ross 1992). In contrast, the size class distribution was bimodal during the dry season, rep- resenting both juvenile recruits (10-20 mm SL) and repro- ductive adults (81-120 mm SL). The bimodal pattern shift- ed to larger sizes in the rainy season, with fish between 40-60 mm SL being most numerous, followed by a cohort of fish between 140-160 mm SL. We propose 2, non- exclusive explanations for the lack of larger Mayan cich- lids collected in our study. First, the populations may suf- fer from overfishing as has been documented in the Celestun Lagoon, Mexico (Martmez-Palacios and Ross 1992); the minimum commercial size for this species in the Alvarado lagoonal system is 150 mm SL. Second, larg- 128 Ecology of the Mayan cichlid Figure 5. Monthly ovarian classes of Cichlasoma urophthalmus in the Alvarado lagoonal system, Veracruz, Mexico. Individual sample sizes by month are provided above each histogram. No collections were made in August and October 2000. er fish have been shown to migrate to deeper water habitats in Florida systems (Faunce et al. 2002), and we suggest our inability to collect larger Mayan cichlids is due in part to our shallow water sampling techniques and we used rela- tively small seines. In fact, we did not collect individuals in spawning or post-spawning condition during this study, which may suggest that Mayan cichlids select other sites in the lagoonal system or immediately offshore to complete their reproduction. For example, Mayan cichlids have been observed breeding in seawater over sand on the barrier reef behind St. George Cay (Greenfield and Thomerson 1997), a different habitat type than those sampled in the Alvarado lagoonal system. Mayan cichlids with large (x = 1.72 mm) diameter oocytes were captured in Celestun Fagoon, Mexico, where mean salinity ranged from 16-24 psu (Martmez-Palacios and Ross 1992); these diameters are much higher than any value measured in the Alvarado lagoonal system. The diet of Mayan cichlids was principally herbivo- rous but varied seasonally, most likely in response to prey availability. Although plant material was the main food item, diet in the dry season was composed of a consider- able portion of crustaceans, insects, and mollusks, similar to findings by Chavez-Fopez (1998). Mayan cichlids col- lected in Thalassia testudinum grassbeds in Terminos Fagoon, Mexico, were mainly ingesting plant and detrital matter, with sponges and cirripeds as incidental food (Caso-Chavez et al. 1986). In contrast, Mayan cichlids (96-200 mm SF) in the Celestun Fagoon, Mexico, were classified as carnivorous, feeding mainly on small inverte- brates (palaemonid and penaeid shrimp) with little algae or seagrass (Martmez-Palacios and Ross 1988). Finally, Bergmann and Motta (2004), based on diet and trophic morphology, indicated that Mayan cichlids in southern Florida were generalists, feeding on fish and snails, and that being generalist and opportunistic feeders enhanced its colonization success in non-native environments. It appears the reproductive season is more prolonged in coastal Mexican lagoons, likely caused by factors such as temperature and day length (Noakes and Baton 1982, Munro et al. 1990). Although Mayan cichlids have a pro- tracted reproductive period in the Alvarado lagoonal sys- tem, we found females with mature eggs only between May and July. Caso-Chavez et al. (1986) reported that reproductive activity was maximal in June and no repro- ductive females were collected after September in Terminos Fagoon, Mexico. Martmez-Palacios and Ross (1992) indicated that the reproductive season began in mid-April and ended by mid-November in the Yucatan Peninsula. In contrast, the reproductive season in Florida appears to occur only in April and May (Foftus 1987, Faunce and Forenz 2000). The reproductive season in 129 ChAvez-Lopez et al. Mexico (Martmez-Palacios and Ross 1992) stopped when temperatures dropped below 24 °C, from late-November to March, whereas in Florida, reproduction stopped in October at 23 °C (Faunce and Lorenz 2000). In the Alvarado lagoonal system, we did not find mature females in the coldest months of the year (January and February) when water temperature had decreased to 23 °C. Our data are comparable with all other reports that sexual maturation occurs by 100 mm SL in Mayan cich- lids. In the Yucatan Peninsula, Mexico, the minimum size for female maturity is 102 mm SL, enabling females to reproduce during their first spring as they approach their first birthday (Martmez-Palacios and Ross 1992). Females in Terminos Lagoon, Mexico, reached sexual maturity at 60 mm SL (Caso-Chavez et al. 1986). We also found mature females as small as 60 mm SL but only in July toward the end of the reproductive season. In contrast, Mayan cichlids from northern locations in Florida reach 50% sexual maturity at 127.2 mm SL (Faunce and Lorenz 2000), suggesting there may be latitudinal variation in size at maturity as reported for other cichlid species (Turner and Robinson 2000). Surprisingly, we found no relationship between female size and fecundity for Mayan cichlids in the Alvarado lagoonal system, although a significant positive relationship has been previously reported for this species in Celestun Lagoon, Mexico (Martmez-Palacios and Ross 1992). The small sample size for fecundity estimates may contribute to the lack of a significant relationship. Even when a significant relationship is seen between fish size and fecundity, size explains only 33% of the variation in fecundity (Martmez-Palacios and Ross 1992). Nonetheless, the range of fecundity values we obtained overlap the low end of the range reported by Martmez- Palacios and Ross (1992; 2085-6615 ova/female, 113-198 mm SL) and were based on smaller fish (87-146 mm SL) than those in the Yucatan. Camaronera Lagoon, the northern part of the system, had the highest salinity between April and June (dry sea- son), when the majority of reproductive activity occurs and when nest construction and parental care occurs in Florida populations (Faunce and Lorenz 2000). The rainy season begins in July and the salinity decreases to 5 psu in this zone as the water levels begin to increase. This coincides with the termination of parental care and the migration of juveniles to other areas to find lower salinity and warmer temperatures (34 °C in Alvarado Lagoon). In the lower salinities common during the rainy season, juveniles are in an almost isotonic aquatic medium at salinities which facilitate the best growth of Mayan cichlids < 1 year old (Martmez-Palacios et al. 1990). Furthermore, the abun- dance of adults decreases in the shallow areas of the lagoonal system during the rainy season, suggesting they may move to deeper areas with higher salinities. In spite of the wide distribution of Mayan cichlids in the southeast of Mexico, until now little was known regarding the state of natural populations. Some popula- tions of Mayan cichlids that inhabit cenotes (sinkholes) in the Yucatan Peninsula are considered species of special concern in Mexico (Diario Oficial de la Federacion 2002). However, Mayan cichlids were suggested as a native aqua- culture resource in Mexico, with presumed lack of a nega- tive effect on native biodiversity (Ross and Beveridge 1995). In contrast, Mayan cichlids are one of the most abundant exotic species established in southern Florida (Trexler et al. 2000), where they severely impact native substrate spawners like largemouth bass (Micropterus salmoides), warmouth {Lepomis gulosus), and spotted sun- fish (L. punctatus) through nest building, habitat alteration, and egg predation. Since Mayan cichlids outnumber native species in northern Florida Bay, more research is needed on community level impacts in brackish water. Thus, a greater understanding of the life history of the species in low salinity systems in its native range may aid manage- ment of introduced populations in south Florida. Acknowledgments This work is based on a senior thesis by A. A. Morales- Gomez. Graduate students, C. Hurtado, I. Sayago, and G. 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Transactions of American Pisheries Society 123:101-107. Trexler, J.C., W.P. Loftus, P. Jordan, J.J. Lorenz, J.H. Chick, and R.M. Kobza. 2000. EmpMcal assessment of fish introduc- tions in a subtropical wetland: An evaluation of contrasting views. Biological Invasions 2:265-277. Turner, G.P. and R.L. Robinson. 2000. Reproductive biology, mating systems and parental care. In: M.C.M. Beveridge, and B.J. McAndrew, eds. Tilapias: Biology and Exploitation. Kluwer Academic Publishers, Dordrecht, The Netherlands, p 33-58. 131 Gulf and Caribbean Research Volume 17 Issue 1 January 2005 Seasonal and Spatial Patterns in Salinity^ Nutrients^ and Chlorophyll a in the Alvarado Lagoonal System^ Veracruz^ Mexico Angel Moran-Silva Universidad Nacional Autonoma de Mexico Luis Antonio Martinez Franco Universidad Nacional Autonoma de Mexico Rafael Chavez-Lopez Universidad Nacional Autonoma de Mexico Jonathan Franco-Lopez Universidad Nacional Autonoma de Mexico Carlos M. Bedia-Sanchez Universidad Nacional Autonoma de Mexico et al DOI; 10.18785/gcr.l701.14 Follow this and additional works at; http://aquila.usm.edu/gcr & Part of the Marine Biology Commons Recommended Citation Moran-Silva; A., L. A. Martinez Franco, R. Chavez-Lopez, J. Franco-Lopez, C. M. Bedia-Sanchez, F. C. Espinosa, F. G. Mendieta, N. J. Brown-Peterson and M. S. Peterson. 2005. Seasonal and Spatial Patterns in Salinity, Nutrients, and Chlorophyll a in the Alvarado Lagoonal System, Veracruz, Mexico. Gulf and Caribbean Research 17 (l); 133-143. Retrieved from http:// aquila.usm.edu/gcr/voll7/issl/14 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contactJoshua.Cromwell@usm.edu. Gulf and Caribbean Research Vol 17, 133-143, 2005 Manuscript received January 29, 2003; accepted December 7, 2004 SEASONAL AND SPATIAL PATTERNS IN SALINITY, NUTRIENTS, AND CHLOROPHYLL a IN THE ALVARADO LAGOONAL SYSTEM, VERACRUZ, MEXICO Angel Moran-Silva, Luis Antonio Martinez Franco, Rafael Chavez-Lopez, Jonathan Franco-Lopez, Carlos M. Bedia-Sanchez, Francisco Contreras Espinosa^, Francisco Gutierrez Mendieta^, Nancy J. Brown-Peterson^, and Mark S. Peterson^ Laboratorio de Ecologia, Universidad Nacional Autonoma de Mexico, Facultad de Estudios Superiores Iztacala. Av. de los Barrios No.l, Los Reyes Iztacala, Tlalnepantla, Estado de Mexico, C.P. 05490 Mexico, E-mail amorans@servidor.unam.mx ^Laboratorio de Ecosistemas Costeros, Universidad Autonoma Metropolitana Unidad Iztapalapa, Mexico ^Department of Coastal Sciences, The University of Southern Mississippi, 703 East Beach Dr, Ocean Springs, Mississippi 39564 USA ABSTRACT Ten monthly collections, distributed among three seasons, were taken from July 2000 to June 2001 in the Alvarado lagoonal system, Veracruz, Mexico. Variables measured in situ included dissolved oxygen, salinity, and water temperature. Water samples were collected to determine concentrations of ammonium, nitrates, nitrites, orthophosphates, total phosphorus and chlorophyll a. Collections representing the rainy season were taken in September and October, those for the nortes season were taken in November, December, and January, and dry sea- son collections were taken during February, March, May June, and July. There was seasonal and spatial variation in nutrient concentrations, and they were related to the discharge of the rivers; concentrations increased during the rainy and nortes seasons. Other factors affecting water quality included the constant discharge of organic materials into the system, resuspension of sediments during the nortes season and the biological activity within the system that assimilated the nutrients in the water. The Alvarado lagoonal system has three separate zones based on physic- ochemical characteristics; Camaronera Lagoon, Buen Pais Lagoon and the urban zone of Alvarado Lagoon, and the river zone in Alvarado Lagoon. RESUMEN Se realizaron diez muestreos durante el periodo comprendido entre Julio de 2000 a Junio de 2001, dis- tribuidos a lo largo de tres estaciones climaticas, en el sistema lagunar de Alvarado, Veracruz, Mexico. Los paramet- ros que fueron registrados in situ incluyendo oxigeno disuelto, salinidad y temperatura de agua. A1 mismo tiempo se colectaron muestras de agua para determinai- en laboratorio las concentraciones de amonio, nitratos, nitritos, orto- fosfatos, fosforo total y clorofila a. Los meses de colecta que abarcaron las temporada de Iluvias fueron tomadas en Julio, Septiembre y Octubre, para Nortes Noviembre, Diciembre, y Enero, y por ultimo, la temporada de secas que correspondieron los muestreos de Febrero, Marzo, Mayo, y Junio. Los nutrientes presentan una variacion espacio- temporal presentando relacion con: la descarga de los rios, incrementandose su concentracion durante la tempora- da de Iluvias y Nortes; las constantes descargas de agua provenientes de diversas actividades humanas, como son la agricultura y los asentamientos humanos; la resuspension de los sedimentos durante la temporada de Nortes; y la gran actividad biologica de estaos sistemas que permiten la rapida transformacion de la materia organica en nutri- entes. El sistema lagunar de Alvarado presenta tres zonas diferentes basadas en sus caracteristicas fisicoquimicas: Laguna de Camaronera, Laguna de Buen Pais y la zona urbana de Laguna de Alvarado, y la zona de rios en Laguna de Alvarado. Introduction Coastal lagoons are productive aquatic systems with a large amount of energetic input. They frequently show ele- vated concentrations of nutrients (Mee 1978), and many are considered eutrophic. Annually, the constant wind- driven movement of the water column resuspends sedi- ments, which furnishes nutrients to the water column through the biogeochemical cycle and the transformation of materials that were in the sediments (Colombo 1977). Rivers and their drainages provide additional nutrients. These nutrients can exhibit large seasonal variation, with the highest concentration generally found following a rainy period. Minimal concentrations are detected after the spring phytoplankton bloom, although even in those months, the concentration of nutrients is higher than that in the adjacent coastal zone (De la Lanza and Arenas 1986). In Mexico, estuarine lagoonal systems represent 30 to 35% of the coastal areas, and 42 of the 134 lagoons are found along the coast of the Gulf of Mexico (GOM) and the Caribbean Sea (Contreras 1985). The estuarine systems along the GOM are generally bordered by well developed 133 MorAn-Silva et al. marsh zones, and the ocean influence is accentuated (Kennish 1986). However, in the southern GOM, estuarine systems are generally bordered by mangroves and the degree of oceanic influence varies greatly. In these systems, many factors such as salinity show great seasonal variation. It is common to encounter a gradient where the salinity is higher near the inlets and decreases towards the rivers. Typically, three seasons (rainy, dry and nortes) define the hydrological behavior of the southern GOM systems (Gomez 1974, Villalobos et al. 1975, Lankford 1977, Botello 1978, Contreras 1988). The rainy season usually occurs from June through September and is characterized by consistent rainfall and large terrestrial runoff, resulting in frequent floods, turbid waters and additional pressures due to the influence of drainage from the land (Contreras 1985). During this season there are brief times of calm weather, characterized by cessation of the rains, high tem- peratures and elevated rates of evapotranspiration. During these periods, extraordinary photosynthesis occurs, with values occasionally exceeding 700 mgC/m^/h and elevated concentrations of chlorophyll <3 of 100 mg/m^ (Contreras 1994). The dry season is typically from March through June and has minimal rainfall and river flow (Villalobos et al. 1975, Contreras 1983). The dry season is characterized by elevated temperature, clear water and relative stability in phytoplankton diversity, and the lagoon is generally affected by the dominance of ocean water mass. The high- er salinity found during the dry season may be due to evap- oration and the reduced influence of the rivers (Villalobos et al. 1966, Contreras 1983). During the nortes, or winter season (October-February), there are strong winds blow- ing from the north off the GOM and temperatures are low (Herrera and Comin 1995, Barreiro and Aguirre 1999). Autotrophic processes dominate over heterotrophic processes, and there is a considerable quantity of dissolved organic material including organic phosphorus. The Alvarado lagoonal system is a typical coastal estuary along the southern GOM that supports a variety of different activities, such as fishing, transportation and urban development. A previous study on the hydrography and productivity of this system identified 5 distinct areas, determined by water temperature and chlorinity, within the lagoon: areas with marine influence, areas with freshwater influence, a gradient area, a calm area and the coastal adja- cent area (Villalobos et al. 1966). These authors also estab- lished that the hydrological and biological characteristics of the lagoon were clearly defined by the rainy and dry seasons. The lagoon is polyhaline with a tendency towards being mesohaline during the dry season and becomes almost totally freshwater during the rainy season (Villalobos et al. 1975). The biological productivity in the system is high, and primary production and the number of phytoplankton cells are inversely related to the phyto- plankton biomass and the postlarval stages of shrimp (Villalobos et al. 1975). More recently, Moran-Silva et al. (1996) reviewed the general hydrological behavior of the Alvarado lagoonal system. They concluded that the hydro- logical conditions are a direct result of the fluvial dis- charges and found the lagoon to be predominantly oligoha- line. Higher salinity values were found only during the dry season or near the inlets and water temperature varied sea- sonally. The shallow depth throughout the system, in com- bination with the winds, allows mixing and aeration of the water column despite the high primary production observed. High nutrient concentrations were found near river mouths, mangroves, and submerged vegetation, pre- sumably through degradation of organic material and resuspension of the sediments. However, the Moran-Silva et al. (1996) study did not examine the seasonal differences in nutrients in the system. Thus, the principal objective of this work is to describe, analyze and characterize the sea- sonal-scale patterns of the salinity, physicochemical and nutrient variables and their relationship with chlorophyll a during the dry, rainy and nortes seasons in the Alvarado lagoonal system, Veracruz, Mexico. Study Area The Alvarado lagoon system is located in the coastal plain of the GOM, 63 km southeast of the port of Veracruz, between 18°46 and 18°42N and 95°34 and 95°58 W (Figure 1). Lankford (1977) considered the system to be a drowned river valley. The lagoonal system consists of 3 smaller lagoons with a total length of about 27 km and a surface area of 6,200 ha. Alvarado Lagoon, the main body of water, continues to the west into Buen Pais Lagoon, which is connected to Camaronera Lagoon through a nar- row channel to the west. The primary connection to the ocean is Alvarado Inlet, situated at the northeast of the sys- tem. A small, 400 m wide outlet to the ocean was con- structed in 1982 in Camaronera Lagoon. The Papaloapan River discharges into Alvarado Lagoon from the southeast. Tidal influence does not diminish the outflow of this river, and mean daily flow into the lagoon is 40 million m^ (Contreras 1985). This system is classified as a positive estuary, because the surface water evaporates at a lesser rate than water is added by the river flow (McLusky 1981). This characteristic is in contrast to many lagoonal systems that are hypersaline due to high evaporation and low fresh- water input. The climate of the area is tropical and humid, and pre- cipitation during the summer ranges from 110 to 200 cm. The mean annual temperature varies between 22-26 °C, 134 Seasonal and Spatial Patterns in Water Quality 95 * 42 ^^ Camaronera Lagoon GULF OF MEXICO Buen Pais iLagoon • a Alvarado Lagoon Alvarado Figure 1. Map of sampling locations in the Alvarado Lagoon system, Mexico. with temperature oscillations between 5-7 °C between each season (Garcia 1973). The prevailing southeast winds have a maximum velocity of 14.4 msec ^ except for October, when winds from the north and northeast range from 90-129.6 msec“^ (Contreras 1985). The lagoon is almost entirely surrounded by man- groves with the typical zonation pattern of red mangrove, Rhizophora mangle, bordering the water and black man- grove, Avicennia germinans, and white mangrove, Laguncularia racemosa, immediately interior. Other spo- ratically occurring aquatic vegetations include wild celery, Vallisneria americana\ cordgrass, Spartina sp.; and cattail, Typha sp.; while the dominant submerged aquatic vegeta- tion (SAV) is Ruppia maritima (Moran-Silva et al. 1996). During the rainy season, the water lily, Eichhornia cras- sipes, invades the lagoon. Materials and Methods Twelve stations were established throughout the Alvarado lagoonal system (Figure 1) to detect the influ- ence of rivers, inlets, SAV and urban discharges. We defined groups for each system: Camaronera group includes stations 10-12; Buen Pais group includes stations 8-9; the Alvarado Lagoon group (urban dominated) includes stations 5-7; and finally the river dominated group includes stations 1-4 in Alvarado Lagoon. Sampling occurred at about 30 d intervals between July 2000 and June 2001. Water temperature (°C) was measured with a mercury thermometer, salinity (psu) with a YSI model 33 salinometer and dissolved oxygen (D.O., ml/1) with a YSI model 51b meter during each collection. Surface water samples were collected at each station for nutrient concen- tration determination. Methods follow Contreras (1994) for ammonium (NH 4 , mg-at/1), nitrate (NO 3 , mg-at/1), nitrite (NO 2 , mg-at/1), phosphate (PO 4 , mg-at/1), and total phosphorus (P-TOT, mg-at/1). Determination of chloro- phyll a (chi a, pg/1) follows techniques in SCOR- UNESCO (1980). The samples were kept on ice for 48 h prior to analysis (Strickland and Parsons 1972, Wetzel and Likens 1990). We used correlation analysis to examine the relation- ship between nutrient concentration and chi a (Daniel 1977). Dendrograms were constructed of temporal and spatial classification with Euclidian distance (values range from 0 , when entities are identical, to infinity) using the monthly salinity data from each station. Classification of the system using salinity followed the procedure of Carriker (De la Lanza 1994). For all analyses we used the Community Analysis Program (ANACOM) 3.1 (De la Cruz, 1994), and results were considered significant if P < 0.05. 135 MorAn-Silva et al. Results Physicochemical variables Salinity varied among all stations from 14.2 psu dur- ing the dry season in June to 0.0 psu during the rainy sea- son in September. The lowest salinity values were always associated with the rivers (0-7.1 psu), whereas the highest values were found in Camaronera and Buen Pais Lagoons (Figure 2a). Salinities at the Alvarado Lagoon stations showed the highest values in March. Dissolved oxygen varied from 12.8 ml/1 in Camaronera Lagoon to 4.13 ml/1 in the stations of the river group. The highest D.O. values were found during the dry season, and values for all stations peaked in May (Figure 2b). The D.O. values at the Alvarado Lagoon group sta- tions fluctuated more than those from the other stations. Water temperature varied seasonally, with annual vari- ation ranging from 21.6 °C during the nortes season to 32.2 °C during the rainy season (Figure 2c). Water temper- ature tended to be higher in the Alvarado Lagoon zone and lower in the stations with river discharge throughout the year. Nutrients Ammonium was the dominant form of inorganic nitrogen, representing 60.98 to 88.3 % dissolved inorganic nitrogen (DIN). The highest ammonium concentration was 42.43 pg-at/1 during the dry season in Buen Pais Lagoon, and the lowest was 2 pg-at/1 during the dry season in Camaronera Lagoon (Figure 3a). In general, the highest ammonium values were found at the river group stations and in Buen Pais Lagoon. The highest nitrite concentration was 3.54 pg-at/1 during the dry season at the river stations. Undetectable amounts of nitrite were found during the dry season in Buen Pais and during the rainy season in the Alvarado Lagoon group (Figure 3b). Nitrite peaked in the Alvarado Lagoon group (urban zone) at the end of the nortes season. Nitrates were highest during the nortes sea- son in the urban and rivers zones (7.9-10.6 pg-at/1), and lowest (0.67 pg-at/1) in Camaronera Lagoon during the nortes season (Figure 3c). A smaller peak of nitrate was evident in all stations at the end of the dry season. Camaronera Lagoon had the greatest range in total phosphorus, with highest values during the rainy season (18.8 pg-at/1) and lowest values during the nortes season (3.5 pg-at/1; Figure 4a). Highest values for all stations occurred during the rainy periods (Figure 4a). The values of orthophosphates were highest at the end of the dry sea- son (4.5-6.2 pg-at/1) and lowest during the rainy season (0.37-0.48 pg-at/1) at all stations (Figure 4b). Chlorophyll a Chlorophyll a values fluctuated during the annual cycle, with lowest values during the dry season (4.3-18.8 pg/1) and highest values in the nortes season (11.5-92.6 pg/1). Buen Pais Lagoon exhibited the greatest fluctuation in chi a (Figure 4c). Overall, the river group stations had the lowest chi a values (5.1-32.1 pg/1). Correlations between chi a and the physicochemical and nutrient meas- urements differed seasonally, but there were no significant correlations between chi a and any other variable meas- ured (Table 1). During the rainy season, there was a mod- erately positive correlation between chi a and salinity and D.O., and a strong negative correlation with ammonium and nitrite. During the nortes season, total phosphorus showed a strong, negative correlation with chi a. Salinity had a moderately positive correlation with chi a during the dry season, while total phosphorous and phosphates were moderately negatively correlated. Spatial-temporal variation The variability of most of the parameters was reflect- ed principally in salinity, which was rapidly modified by the rain and tidal influence. Using salinity in a cluster analysis, three principal groups were evident (Figure 5a). Group 1 consists of the months of September and October, representing the rainy season, when the system was oligo- haline with salinities ranging from 0 to 3.8 psu. Group 2 consists of the months November, December, January and February, corresponding to the nortes season when the salinity begins to increase, ranging from 0 to 1 1.5 psu. The third group corresponds to the dry season (March, May and June 2001), with the highest salinity values (2 to 14.5 psu), resulting in a mesohaline system. However, July is isolated from the other groups. This month corresponded to the rainy season, while June 2001 was more similar to the dry season due to a lack of rain during that year. When cluster analysis was applied to the collection stations, the analysis resulted in three groups separated by marine or freshwater influence (Figure 5b). The first group consisted of stations located in Camaronera Lagoon (12 and 11) that receive direct tidal influence through the inlet and had the highest salinities (up to 21 psu). The second group has stations separated into 2 sub-groups, with sta- tions 8-10, representing the eastern portion of Camaronera Lagoon and Buen Pais Lagoon, as one sub-group and sta- tions 5-7, the urban dominated stations, as the second sub- group. The first sub-group receives some tidal influence and had mean salinities ranging from 6.33 to 8.75 psu, while the second sub-group consisted of lower salinity sta- tions located along the eastern shore of Alvarado Lagoon with a marked influence from urban zones. The final major 136 Seasonal and Spatial Patterns in Water Quality ramamnpra _n_BuenPais _ _a- - Rivers _x - Urban Figure 2. Plot of mean monthly salinity (A), dissolved oxygen (B), and water temperature (C) over the course of the study pooled by sampling stations within each of the four groups. group contained all the stations associated with the river group (1-4) and can be defined as an oligohaline zone. Discussion It is well known that the variability of the hydrologi- cal variables and nutrients is especially marked in lagoon- al systems. This is due to many factors, like the dynamics in the circulation of the lagoon as affected by the tides, the winds, and the shallow depth. Furthermore, constant resus- pension of sediments, regeneration processes originated by microbial activity in the sediments, river flow, and human activities contribute to nutrient variation (Colombo 1977, Snedaker and Brown 1982). As expected, the low salinity values found during the rainy season were a result of the increased freshwater inflow into the lagoonal system (Botello 1978). Similarly, the months corresponding to the dry season (March, May and June in this study) had the highest salinity throughout the system, due to reduced river flow. However, the months 137 MorAn-Silva et al. A B C 0 Camaronera —n—Buen Pais . . Rivers _>^ _ Urban Figure 3. Plot of mean monthly ammonium (A), nitrite (B), and nitrate (C) over the course of the study pooled by sampling sta- tions within each of the four groups. during the nortes season (December, January and February) had salinity values similar to the dry season. Thus, the Alvarado lagoonal system can be considered oligohaline during the rainy season and mesohaline during the nortes and dry seasons. However, the stations close to the river mouth remained oligohaline during the dry sea- son, indicating a weak marine influence in the lagoon (Moran- Silva et al. 1996). Seasonal differences in salinity have been noted previously in other Mexican lagoons, such as the Celestum Lagoon (Herrera-Silveira and Comin 1995) the Tampamachoco Lagoon (De la Lanza et al. 1998), and the Alvarado lagoonal system (Moran-Silva et al. 1996). The lowest D.O. concentrations were encountered in September, which corresponds to the end of the rainy sea- son, when there is an increase in suspended organic mate- rial. When organic material is resuspended, microorgan- isms begin decomposition, removing oxygen from the water column (Kennish 1986). The highest D.O. concen- trations were found associated with seagrass beds, similar 138 Seasonal and Spatial Patterns in Water Quality A B C 20 18 1 16 g 14 S 12 t 10 I « « |5 4 2 0 7 S 5 O) ? Q. 1 0 120 100 1“ TO > 60 JZ Q. P O 40 £ o 20 Dry season Rainy season Nortes season Dry season / \ \ \ / i \ / :) \ 13 / 1 */ X‘* ^ / / p / r ^ -- jA f '/ // ' 7 * fy A ^ % A* ♦ %■ / V / ti <$> / '/ / .Jl L. J y> > / / !] \ \ T / / \ \ / ✓ X/ / \ . \ \ / 1 /✓ V 'A V \ H — /yV -K- -r-\K JulOO Sep 00 Oct 00 Nov 00 Dec 00 Jan 01 Feb 01 Mar 01 May 01 JunOI e Camaronera —n—Buen Pais . .a- . Rivers _a. _ Urban Figure 4. Plot of mean monthly total phosphorus (A), orthophosphate (B), and chlorophyll a (C) over the course of the study pooled by sampling stations within each of the four groups. to reports by Contreras and Gutierrez (1989) for other sys- tems in the state of Veracruz. Overall, D.O. concentrations remained relatively heterogeneous and could be related to photosynthetic activity, seasonality, mixing of water and tidal activity (Botello 1978, De la Lanza and Cantu 1986), or to the presence of SAV throughout the system. With respect to nutrients, the form of ammonia in this type of system comes from degradation of organic materi- al, submerged vegetation and waste from organisms (Tiejten 1968, Botello 1978, De la Lanza and Arenas 1986). Ammonium was the predominant form of inorgan- ic nitrogen during all the seasons. Similarly, Kennish (1986) found that ammonium was the predominant form of inorganic nitrogen in estuarine waters. This agrees with reports by Contreras and Castaneda (1992) and Contreras (1983) for the Tampamachoco Lagoon and the lagoonal system of Carretas-Pereyra, respectively. Maximal ammo- nium values were observed in Buen Pais Lagoon during the dry season, no doubt enhanced by the increasing tem- perature that favors a greater degradation of organic mate- 139 MorAn-Silva et al. A B influence Figure 5. Dendogram based on Euclidean distance of monthly (A) and station (B) salinity values. Station numbers correspond to stations in Figure 1. Cam-Camaronera Lagoon; B.P.-Buen Pais Lagoon; Arb., Rastro, Aneas — urban areas on the north side of Alvarado Lagoon; Blanco-Bianco River, Alvarado Lagoon; Pap.-Papaloapan River, Alvarado Lagoon rials found in the sediments as well as increased waste from organisms in the water column. However, Kennish (1986) indicated that the concentrations of the nitrogenous components can be augmented with the river flow. We observed a similar increase in the river group stations dur- ing September, a time of high river flow in Alvarado Lagoon. Day et al. (1998) reported a similar situation in Terminos Lagoon, showing augmentation of nutrient con- centrations during times of high discharge from the rivers. Buen Pais Lagoon had generally higher values of ammonium than the other two lagoons within the system, with a peak in March. This may be due to slower water cir- culation in this lagoon relative to the others in the system (Villalobos et al. 1975). In contrast, the urban areas of Alvarado Lagoon did not have an increase in nitrogen in March, although there were peaks in June and December. Alvarado Lagoon is impacted by urban discharges from the Port of Alvarado, which tend to increase the nitrogen concentration in the water (Barreiro and Aguirre 1999). This was particularly evident for nitrate during the nortes season. The Lagoon showed notable hydrological variation on spatial as well as temporal scales. For instance, eutrophica- tion was noted in semi-isolated areas such as within canals, which had minimal effects of circulation, yet the rest of the Lagoon was not eutrophic. On a temporal scale, the dry and wet seasons result in changes in salinity and nutrients with consequent variation in the habitat during the annual cycle. 140 Seasonal and Spatial Patterns in Water Quality TABLE 1 Seasonal correlation coefficients (Pearson’s r) between chlorophyll a and various water chemistry variables in the Alvarado lagoonal system. No values were signifi- cant at P < 0.05. Variables Rainy Nortes Dry Salinity (psu) 0.55 -0.04 0.43 Dissolved oxygen (ml/1) 0.59 -0.15 0.02 Temperature (°C) 0.35 -0.24 0.29 Ammonium (pg-at/1) -0.65 0.29 0.10 Nitrite (pg-at/1) -0.14 0.27 -0.20 Nitrate (pg-at/1) -0.74 -0.13 0.15 Phosphate (pg-at/1) -0.15 0.14 -0.37 Total phosphorous (pg-at/1) -0.20 -0.62 -0.47 The nutrient concentrations reached during the rainy sea- son were more elevated than during the dry season. The Alvarado lagoonal system had the highest phos- phorus concentration during the rainy season. While this nutrient comes principally from organic material, it is also produced through autochthonous processes such as biotur- bation and remineralization of the sediments and remixing by currents (Groen 1969). Total phosphorus was highest during September throughout the lagoonal system, no doubt due to the effects of increased river runoff and resus- pension of the sediments (Groen 1969). Concentration decreased gradually to the lowest point during the dry sea- son. A peak of orthophosphates in June may be related to the decrease in chi a concentration during this month, as phytoplankton utilize orthophosphates (Contreras and Castaneda 1992). Overall, Camaronera Lagoon had the lowest concentration of phosphates, probably because cur- rents are minimal, resulting in little resuspension of the sediment where the majority of phosphates are stored (De la Lanza 1996). In Alvarado Lagoon, phosphates were higher during the nortes and dry seasons compared to the rainy season, and variation was not as great as in the other lagoons. The variation in phosphate that was observed is probably a direct result of river input. The agricultural land and associated fertilizers within the drainage basin of the Papaloapan River are important sources of phosphates (Correll et al. 1992), which can be transported into the lagoon through erosion and runoff. A global characteristic of lagoonal phytoplankton is their high productivity. For this reason, we consider coastal lagoons as ecosystems with characteristics intermediate between the ocean and the rivers (Margalef 1969). Since algae are the only organisms that remain constant with respect to other cellular components that are ecologically important, chi a concentration can be used to better under- stand the dynamics of the system (Marshall 1987). Unfortunately, the coefficients of correlation did not show a significant relation between the concentration of chi a and the physicochemical variables. There is usually a strong relationship between nutrient concentration and chi a concentration, as has been previously discussed (Contreras 1994). We found an increase from undetectable chi a in July to moderate levels (14-42 pg/1) in September and October, similar to findings in other Mexican lagoon- al systems (Contreras et al. 1992, Contreras and Castaneda 1992, Barriero and Aguirre 1999). Interestingly, the high- est correlation between D.O. and chi a was found during this time, when chi a began to increase from a dry season low, suggesting an increase in productivity. During November and December, chi a again decreased in most areas of the lagoon, and chi a values were higher from January through March, with a peak in February. The high chi a values in Buen Pias Lagoon during February (96.2 pg/1) indicate a hypereutrophic system at that time. The February peak corresponds to the end of the nortes season, a time when Li et al. (2000) found an association of phy- toplankton blooms with a peak of nutrients. The decrease in chi a during May and June may be related to the increase in phosphates and inorganic phosphorus during this time. Barreiro and Aguirre (1999) found that an increase in nitrate during the rainy season is necessary for a phyto- plankton bloom to commence during the dry season. Our data show a dramatic increase in nitrate during November and December, which may be related to the bloom, and a subsequent increase in chi a in February. The predomi- nance of blooms during the dry season may also be related to calmer water conditions during this time (Marshall 1987). Overall, the pattern of chi a was relatively similar among stations and lagoons, with peaks and low points occurring during similar times. Spatial patterns of chi a respond to local conditions (Barreiro and Aguirre (1999), and the estuarine currents can distribute the phytoplankton biomass asymmetrically (Li et al. 2000). For instance, phy- toplankton populations from the ocean may enter the lagoon on incoming tides (Revilla et al. 2000), which may explain the increased chi a concentration near the inlet in Camaronera Lagoon during September, January and February. On the other hand. Revilla et al. (2000) found that the major concentration of chi a in estuaries was found in discharge areas that did not receive a direct tidal influ- ence. Similarly, Day et al. (1998) found a major concentra- tion of chi a in Estero Fargo (mean annual value 8 pg/1) in comparison to Terminos Lagoon (3 pg/1). However, our 141 MorAn-Silva et al. data show that the chi a concentration was low at stations located at the Papaloapan and Blanco rivers, where there is major discharge but minor tidal influence. In terms of spatial distribution, it is possible to distin- guish areas directly influenced by terrestrial sources due to elevated quantities of phosphorus. These are interpreted as areas within the lagoonal system with a greater density of primary producers, compared to other zones where differ- ent factors, such as circulation, river influence, or winds do not permit the accumulation of phytoplankton. The persist- ence of these phytoplankton overloaded areas is the direct cause of natural eutrophication or eutrophication originat- ed by urban activities. Natural eutrophication is a result of geographic properties, accumulation of sediment, etc., while anthropogenic eutrophication is a result of uncon- trolled use of fertilizers, deforestation, and addition of con- taminants and human wastes to the lagoonal system. The continued urban development along the internal coast of the Alvarado Lagoon exacerbates the anthropogenic inputs to the system. Finally, there has been a change in the bot- tom use in the discharge area of the Papaloapan River that has altered the hydrological dynamics. Our results suggest that habitats within the lagoonal system have high heterogeneity that is driven by variation in salinity and water temperature. This variation is the result of the influence of river discharge and tidal exchange. In addition, these difference may also relate to the bathymetry, the presence of SAV or the proximity of mangroves. However, our results do not correspond to those reported by other authors. Villalobos et al. (1966) described 5 natural areas based on the influence of the rivers and the ocean, whereas in this work, we define only 3 such areas, which are a function of river discharge, prox- imity to ocean inlets and the influence of urban discharges. Our findings concur with Lozano (1993) who found that an increase of anthropogenic activities, in conjunction with poor planning, contributed to local and regional changes in hydrological characteristics of the freshwater sources to the Alvarado lagoonal system. Salinity characteristics of the Alvarado lagoonal sys- tem vary seasonally. Our work has reinforced the observa- tions of Villalobos et al. (1975) who described the season- al salinity variation. Furthermore, two earlier studies on the Alvarado lagoonal system found that salinity varied more than other variables (Sevilla and Chee 1974) and was lowest during the rainy period (Sevilla and Chee 1974, Chee 1981). It appears that the amount of rainfall and sub- sequent river discharge is one of the forces driving the vari- ability of the system. Thus, to better understand the hydrol- ogy of the Alvarado lagoonal system this information is required. Acknowledgements We thank the students from the Ecology Laboratory at FES-Iztacala as well as the fishing community at Alvarado Port, Veracruz, Mexico, for their assistance with this proj- ect. The authors thank Dr. W. Boynton of Chesapeake Biological Laboratory for comments on an earlier version of this manuscript. Literature Cited Barreiro, G.M.A. and L.A. Aguirre. 1999. Distribucion espacio- temporal de la biomasa fitoplanctonica en el sistema lagunar Pom-Atasta, Campeche, Mexico. Revista de Biologia Tropical 47 (Supplement 1) 27-35. 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Primary productivity of mangroves. In: O.R. Zaborsky, ed. CRC Handbook on Biosolar Resources, Volume 1. CRC Press, Boca Raton, PL, USA, p. 477-485. Villalobos, P.A., C.J. Suarez, G. De la Lanza, P.M. Aceves, and J. Cabrera. 1966. Considerations on the hydrography and pro- ductivity of Alvarado Lagoon, Veracruz, Mexico. Proceedings of the Gulf and Caribean Pisheries Institute 19:75-85. Villalobos, E.A, S. Gomez, V. Arenas, J. Cabrera, G. De la Lanza, and P. Manrique. 1975. Estudios hidrobiologicos en la Laguna de Alvarado (Pebrero-Agosto 1966) Anales del Instituto de Biologia. Universidad Nacional Autonoma de Mexico. Serie Zoologia (l):l-34. 143 Gulf and Caribbean Research Volume 17 Issue 1 January 2005 Long-Term Fish Assemblage Dynamics of the Alvarado Lagoon Estuary Veracruz^ Mexico Rafael Chavez-Lopez Universidad Nacional Autonoma de Mexico Jonathan Franco-Lopez Universidad Nacional Autonoma de Mexico Angel Moran-Silva Universidad Nacional Autonoma de Mexico Martin T. O'Connell University of New Orleans DOI; 10.18785/gcr.l701.15 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Chavez-Lopez, R., J. Franco-Lopez, A. Moran-Silva and M. T. O'Connell. 2005. Long-Term Fish Assemblage Dynamics of the Alvarado Lagoon Estuary, Veracruz, Mexico. Gulf and Caribbean Research 17 (l): 145-156. Retrieved from http://aquila.usm.edu/gcr/voll7/issl/15 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf and Caribbean Research Vol 17, 145-156, 2005 Manuscript received January 26, 2004; accepted December 13, 2004 LONG-TERM FISH ASSEMBLAGE DYNAMICS OF THE ALVARADO LAGOON ESTUARY, VERACRUZ, MEXICO Rafael Chavez-Lopez, Jonathan Franco-Lopez, Angel Moran-Silva, and Martin T. O’Connell^ Laboratory of Estuarine Ecology, Eacultad de Estudios Superiores Iztacala, Universidad Nacional Autonoma de Mexico, Av. de los Barrios No.l, Los Reyes Iztacala, Tlalnepantla, Estado de Mexico, C.P. 05490 Mexico, E-mail rafaelcl@servidor.unam.mx ^ Pontchartrain Institute for Environmental Sciences, 2000 Lakeshore Drive, University of New Orleans, New Orleans, Louisiana, 70148 USA, E-mail moconnel@uno.edu ABSTRACT The fish assemblages of Alvarado Lagoon Estuary (a complex of coastal lagoons in the state of Veracruz, Mexico) have been surveyed intermittently by different researchers over the last 40 years. Assessing long- term trends in fish assemblage composition for this ecosystem is problematic due to differences in sampling efforts among the survey periods (1966-1968, 1987-1988, 1989, 1989-1990, 1990-1991 and 2000-2001) and by the inherent ecological variability of estuaries. To overcome these data limitations and better understand fish assem- blage change over time, we used robust, simulation-based analyses to compare collections from the different sur- veys. The 107 fish species collected from the Alvarado Lagoon Estuary in these surveys represent 4 ecological guilds: marine stenohaline, marine eury haline, estuarine, and freshwater fishes. The occurrence frequency of fish species representing each guild did not change significantly among the survey periods: the chi-square deviation sta- tistic ( ^ = 8.53) was not significantly larger than the average value for 1000 simulated matrices ( ^= 138.64;P = 1.00). A non-metric multidimensional scaling (MDS) based on Bray-Curtis similarities of fish species presence- absence data showed that the 1966-1968 survey period was the least similar to the other survey periods. Eor the 1966-1968 survey, the range of Bray-Cuitis inter-survey similarities was 40.4-58.6 {n = 5). By comparison, the remaining range of inter-survey similarities was 61.5-81.7 {n = 10). Average taxonomic distinctness (A"^) and vari- ation in taxonomic distinctness (A"^), two sample size-independent measures of diversity, were calculated for all sur- vey periods. Although and A"^ for all survey periods were within the simulated 95% confidence limits for expect- ed values, these values for the 2000-2001 survey period were less than the average A"^ and A"^ values for the entire species pool. This suggests that the fish assemblage collected during the latest survey reflects a loss of both wide- spread higher taxa (reduced A"^) and that the higher taxa lost are those with only a few representative species in the assemblage (reduced A"^). These assemblage data show that fish assemblages of Alvarado Lagoon Estuary have not experienced significant changes over 40 years, but differences among the earliest (1966-1968), the latest (2000-2001), and the remaining survey periods indicate a recent decline in diversity. RESUMENUos ensamblajes de peces del sistema lagunar de Alvarado (un complejo de lagunas costeras del Estado de Veracruz, Mexico) han sido investigados intermitentemente por diferentes grupos durante los ultimos 40 anos. La determinacion de las tendencias a largo plazo de estos ensamblajes ha sido problematica debido a las diferen- cias en los esfuerzos de muestreo empleados entre los periodos de investigacion (1966-1968, 1987-1988, 1989, 1989-1990, 1990-1991 y 2000-2001) y por la variacion ecologica inherente a los estuarios. Para evitar estas lim- itaciones de los datos y presentar una explicacion apropiada de los cambios de los ensamblajes de peces respecto al tiempo, se uso un analisis de simulacion para comparar las colectas de los diferentes periodos de trabajo. Las 107 especies colectadas en el sistema lagunar de Alvarado representan 4 gremios ecologicos: marino estenohalino, mari- no eurihalino, estuarino y dulceacuicolas. La frecuencia de ocurrencia de las especies de peces que representan cada gremio no cambio significativamente entre los periodos de investigacidn: El estadistico de desviacion chi cuadrada ( ^ = 8.53) no fue significativamente mas grande que el valor promedio para las 1000 matrices simuladas ( ^ = 138.64; P = 1.00). La prueba de escalamiento multiple dimensional no-metrico (MDS) se ejecuto considerando los datos de presencia-ausencia y las similitudes calculadas por el mdice de Bray-Curtis, esta prueba mostro que el periodo 1966-1968 fue menos similar a los otros periodos de colecta. Para el periodo 1966-1968, el rango de simil- itudes Bray-Curtis entre investigaciones fue de 40.4-58.6 {n = 5). En comparacion, el rango de similitudes restante entre investigaciones fue de 61.5-80.7 (n = 10). La distincion taxonomica promedio (A"^) y la variacidn de la dis- tincion taxonomica (A"^), dos medidas de la diversidad independientes del tamano de muestra, fueron calculadas para todos los periodos de investigacion. Aunque los valores de A"^ y A"^ para todos los periodos de investigacion estuvieron dentro de los limites de confianza de 95% para los valores esperados, estos valores fueron menores para el periodo 2000-2001 respecto a los valores promedio de A"^ y A"^ para el conjunto complete de especies. Esto sug- iere que el ensamblaje de especies colectado en el ultimo periodo de investigacion refleja una perdida de taxa supe- riores (A"^ reducida) y que los taxa superiores perdidos son aquellos con pocas especies representativas en el ensam- blaje (A+ reducida). Estos datos muestran que los ensamblajes de especies del sistema lagunar de Alvarado no han sufrido cambios significantes durante los ultimos 40 anos, pero las diferencias entre el primer y ultimo periodo de investigacidn y los otros periodos indican una declinacion reciente en la diversidad. 145 ChAvez-Lopez et al. Introduction Coastal lagoons are interface ecosystems that have a rich biodiversity of organisms due to their position between river drainages and the continental shelf. The environmental gradients within coastal lagoons typically allow for numerous species with various life cycles, result- ing in the formation of communities whose structures are influenced by physical and chemical factors. These ecosystems are dynamic and vary seasonally, which influ- ences the presence of organisms from marine or freshwa- ter origin and creates an environment that is critical for commercially important species such as molluscs, crus- taceans, and fishes (Beck et al. 2001, Blaber 2002). The Alvarado Lagoon Estuary is a complex of coastal lagoons located in southern Veracruz, Mexico. The Papaloapan, Blanco, and Acula rivers drain into the estu- ary, which in turn drains north into the Gulf of Mexico near Alvarado Port. The largest of these river basins, the Papaloapan River Basin, is more than 500 km long, covers an area of 46,517 km^, and has an annual discharge of 47 million m^. The combination of numerous freshwater sources and multiple connected lagoon complexes forms a rich coastal ecosystem in the Alvarado Lagoon Estuary (Chavez-Lopez 1998). However, environmental and eco- logical changes due to anthropogenic factors such as over- exploitation of the resources, industrial contamination, and construction of dams have contributed to the progressive decrease in the quality and ecological value of estuaries (Whitfield and Elliot 2002). This increasing alteration of environmental quality and quantity contrasts with the recent classification of lagoonal systems as strategic areas for the conservation of biodiversity (CONABIO 1998, Zarate-Lomeh et al. 1999). If the biodiversity of the Alvarado Lagoon Estuary is to be protected, it is necessary to determine which organisms are consistently present in the ecosystem and which appear to be declining in response to increased anthropogenic impacts. Although the fish assemblages of the Alvarado Lagoon Estuary have been surveyed intermittently over the last 40 years by various researchers, these data have never been analyzed as an entirety to assess possible changes in fish biodiversity over that period. We compared fish collec- tion data for 6 surveys (1966-1968, 1987-1988, 1989, 1989-1990, 1990-1991 and 2000-2001) to determine if the fish assemblages had changed among the survey peri- ods. More specifically we addressed the following ques- tions: 1) Did the frequency of marine stenohaline, marine euryhaline, estuarine, and freshwater fishes change signif- icantly among surveys?, 2) Did assemblages remain simi- lar throughout the 40 year period as determined by Bray- Curtis similarity indices?, and 3) Did biodiversity decline significantly over the same period as determined by com- parisons of average taxonomic distinctness and variation in taxonomic distinctness (two sample size-independent measures of biodiversity)? Study Area The Alvarado Lagoon Estuary is comprised of the Alvarado, Buen Pais, and Camaronera lagoons and the estuarine zone of the Papaloapan River (Eigure 1). This estuarine system has a total surface area of 6,200 ha, with a mean depth of 2.5 m in the central zone of the lagoon and 14 m in the channel of the Papaloapan River. Water tem- peratures from April to September range between 27-33 °C, while during winter months (December to Eebruary) water temperatures reach as low as 22 °C. The salinity varies from 0-10 psu between July and October (rainy season), although during this period salinities are higher at the artificial inlet in Camaronera Lagoon. Erom November through June (nortes and dry seasons) salinities average 16 psu in Camaronera Lagoon and 22 psu at the mouth of the Papaloapan River, whereas the rest of Alvarado and Buen Pais lagoons have salinities ranging from 0-8 psu. Materials and Methods We compiled fish assemblage data for the Alvarado Lagoon Estuary from previous research reports that described past fish surveys (Resendez 1973, Chavez- Lopez 1998). Resendez (1973) provided a list of species collected between 1966 and 1968 using various fishing gear but did not provide precise information on capture methods, abundance, biomass, or physico-chemical vari- ables. Chavez-Lopez (1998) included a list of species as well as abundance, biomass, and ecological variables of the assemblage from November 1987 to August 1991. Our own monthly collections from June 2000 to August 2001 provided the latest data from the Estuary. We sampled fish- es at 12 stations which included various habitat types: sub- mersed aquatic vegetation {Ruppia maritima) (stations 2, 3, 4, and 6), old oyster reefs (station 5), river mouths (sta- tions 7 and 10), the estuarine zone of the Papaloapan River (stations 11 and 12), a station near the artificial inlet that did not have submersed aquatic vegetation (station 1), and 2 stations located near Alvarado Port with urban influence (stations 8 and 9; Eigure 1). Our fish sampling method consisted of a single seine haul with a 30 m long x 2 m high seine with 19 mm mesh, resulting in an effective col- lection area of 27.5 x 27.5 m (756.2 m^). Seines were oper- ated perpendicular to shore at all stations except 11, where 146 Long-term fish assemblage dynamics Figure 1. Map of the Alvarado Lagoon Estuary showing sampling stations for 6 fish surveys conducted during the following periods: 1966-1968, 1987-1988, 1989, 1989-1990, 1990-1991 and 2000-2001. the same area was sampled in a circular pattern. The mean depth of all stations was 0.98 m. All organisms were fixed in 10% formalin and later washed in tap water and pre- served in 70% ethanol. Species identification and common names were verified based on Resendez (1973, 1981, 1983), Fischer (1978), Arredondo and Guzman (1987), Hubbs et al. (1991), Hoese and Moore (1998), and Nelson et al. (2004). From the lists of fishes, we constructed a presence- absence matrix of species based on the 6 collection peri- ods: 1966-1968, November 1987-September 1988, February-September 1989, November 1989 to June 1990, November 1990 to August 1991, and June 2000 to June 2001 (Table 1). All seasons are represented in each collec- tion period except 1989 when no collections were made during the nortes season (November through February). We classified fishes of the Alvarado Lagoon Estuary into 4 ecological guilds: marine stenohaline (M), marine euryha- line (ME), estuarine (E), and freshwater (F). These guilds were based on descriptions in Castro- Aguirre et al. (1978), Chavez-Lopez (1998), and Ross et al. (2001). If a fish specimen could not be identified to species level, it was recognized as “sp.” under its genus epithet and included in the list as a separate species. We used EcoSim software (v. 7.58) to determine if the occurrence frequency of marine stenohaline, marine euryhaline, estuarine, and freshwater fishes differed significantly among surveys. A matrix rep- resenting the number of species from each guild collected from each survey was compared to a matrix representing expected values. For this comparison, expected frequen- cies were represented as the mean frequencies of each guild across all surveys. A chi-square statistic was generat- ed to quantify the level of deviation between the observed and expected matrices. Once this statistic was calculated, EcoSim was used to create 1000 simulated matrices based on a randomization of the observed matrix. For this case, randomization of frequencies was designated to operate across surveys but not across guilds. In other words, if Guild A consistently had roughly twice as many species as Guild B for all 6 surveys, then all simulated matrices reflected this reality. A chi-square deviation statistic was calculated for the comparison of each of these 1000 simu- lated matrices to the expected mean frequencies. The resulting 1000 chi-square statistics were plotted as a fre- quency diagram and compared with the original observed- expected chi-square statistic. If the observed frequencies of species in guilds deviated significantly from random, the original observed-expected chi-square statistic should be greater than at least 950 chi-square statistics generated by the simulated matrices {P = 0.05). 147 ChAvez-Lopez et al. TABLE 1 Fish species collected from the Alvarado Lagoon Estuary during 6 separate surveys from 1966 to 2001. Each species was assigned to one of 4 ecological guilds: marine stenohaline (MS), marine euryhaline (ME), estuarine (E), or freshwater (F). Species occurrence in a collection is denoted by an X with non-occurrences denoted by an 0. Species Ecological Guild 1966-1968 1987-1988 1989 1989-1990 1990-1991 2000-2001 Dasyatis sabina ME X X X X X X Elops saurus ME X X 0 X X X Myrophis punctatus MS X 0 0 0 0 0 Harengula jaguana MS X 0 0 0 0 0 Opisthonema oglinum ME 0 X X X X X Brevoortia gunteri ME X 0 0 X 0 0 Brevoortia patronus ME 0 0 0 X 0 0 Dorosoma cepedianum E 0 X X X X 0 Dorosoma petenense E X 0 X X X 0 Anchoa hepsetus MS 0 X 0 0 0 0 Anchoa mitchilli ME X 0 X X X X Cetengraulis edentulus MS 0 X 0 0 X 0 Sy nodus foetens MS 0 0 0 X 0 0 Astyanax fasciatus E 0 0 0 0 0 X Ictiobus meridionalis E X 0 0 0 0 0 Arius felis ME X X X X X X Cathoropus melanopus E X X X X X X Bagre sp. ME 0 0 0 X 0 0 Bagre marinus ME X X 0 X X X Rhamdia guatemalensis E 0 0 0 0 0 X Opsanus beta ME X X 0 X X X Gobies ox strumosus ME X 0 0 0 0 0 Hemirhamphus bmsiliensis ME 0 0 X 0 0 0 Hyporhamphus roberti ME 0 X X X X X Strongylura marina ME X X X X X X Strongylura notata ME 0 X X X X X Strongylura timucu MS 0 0 0 0 0 X Poecilia mexicana E X X X X X X Belonesox belizanus E X 0 0 0 0 X Menidia beryllina ME 0 0 0 0 X X Membras vagrans MS 0 X 0 0 0 0 Thyrinops sp. E X 0 0 0 0 0 Syngnathus louisianae ME 0 X 0 0 X 0 Syngnathus scovelli ME X 0 0 0 X X Microphis brachyurus ME X 0 0 0 0 X Ophisternon aenigmaticum E X 0 0 0 0 0 Prionotus punctatus MS 0 X 0 X X 0 Centropomus undecimalis ME X X 0 X X X Centropomus parallelus ME X X X X X X Centropomus poeyi ME X 0 0 0 0 0 Centropomus ensiferus ME 0 0 X 0 0 X Centropomus pectinatus ME 0 X X X X X Caranx latus MS X 0 0 X X X 148 Long-term fish assemblage dynamics Table 1 (continued) Species Ecological Guild 1966-1968 1987-1988 1989 1989-1990 1990-1991 2000-2001 Caranx hippos MS X X 0 0 X X Caranx crysos MS 0 0 0 0 0 X Selene vomer MS X 0 X X X X Caranx bartholomei MS X 0 0 0 0 0 Hemicaranx amblyrhynchus MS 0 X X 0 X 0 Trachinotus carolinus ME 0 X X X X 0 Trachinotus falcatus ME 0 0 X X X X Oligoplites saurus ME 0 X X X X X Lutjanus synagris MS 0 0 0 0 0 X Lutjanus apodus MS X X 0 0 0 0 Lutjanus griseus MS X X X X X 0 Lutjanus jocu MS 0 X 0 X X 0 Eucinostomus gula MS 0 X 0 0 0 0 Eucinostomus melanopterus ME X X X X X X Diapterus rhombeus ME X X X X X X Diapterus auratus ME X X X X X X Gerres cinereus MS 0 X X 0 0 0 Eugerres plumieri MS X X X X X X Haemulon plumieri MS 0 0 0 0 X 0 Conodon nobilis MS X 0 0 0 0 0 Pomadasys croco MS X 0 0 0 X X Archosargus rhomboidalis MS 0 X 0 X X 0 Archosargus probathocephalus ME X X 0 X X 0 Lagodon rhomboides MS X X 0 X X 0 Cynoscion nothus MS X 0 0 0 0 0 Cynoscion nebulosus MS X 0 0 0 0 0 Bairdiella ronchus ME X 0 0 X X 0 Bairdiella chrysoura ME X X X X X X Stellifer lanceolatus ME 0 X X X X X Micropogonias furnieri ME X X X X X X Chaetodipterus faber MS 0 0 0 X 0 0 Cichlasoma octofasciatum E X 0 0 0 0 0 Cichlasoma salvini E 0 0 0 0 0 X Vieja fenestrata E X 0 0 0 0 0 Cichlasoma urophthalmus E 0 X X X X X Cichlasoma synspillum E 0 0 0 X 0 X Cichlasoma champotonis E 0 0 0 0 0 X Cichlasoma helleri E 0 X X X X 0 Cichlasoma sp. E 0 0 0 0 0 X Petenia splendida E 0 X X X X X Oreochromis aureus E 0 X X X X X Oreochromis niloticus E 0 X X X X X Mugil curema ME X X X X X X Mugil cephalus ME X X X X 0 X Mugil gaimardianus MS 0 0 X 0 0 0 Agonostomus monticola E 0 0 0 0 0 X Sphyraena barracuda MS 0 X 0 0 X X Polydactilus octenemus MS X X X X 0 0 149 ChAvez-Lopez et al. Table 1 (continued) Species Ecological Guild 1966-1968 1987-1988 1989 1989-1990 1990-1991 2000-2001 Lupinoblennius nicholsi E X 0 0 0 0 0 Gobionellus oceanicus E 0 X X X X X Gobioides broussonetii E X 0 0 X X X Lophogobius cyprinoides E 0 0 0 0 0 X Bathygobius soporator E X X 0 0 0 X Guavina guavina E 0 X X X 0 0 Evorthodus lyricus E X X 0 0 0 0 Lythripnus sp. E 0 0 X 0 0 0 Gobiomorus dormitor E X 0 0 0 X X Dormitator maculatus E X 0 0 X X X Eleotris pisonis E 0 0 0 0 0 X Erotelis smaragdus E 0 X 0 X X X Trichiurus lepturus MS X 0 0 X X 0 Citharicthys spilopterus ME X X X X X X Achirus lineatus ME X X X X X X Trinectes maculatus ME X 0 0 0 0 0 To determine if the species composition of assem- blages changed over time, we used PRIMER (v. 5) soft- ware to generate a non-metric multidimensional scaling (MDS) diagram. This diagram shows the relative similari- ty of fish assemblages in ordinate space based on pair-wise Bray-Curtis similarities of presence-absence data. Fish assemblages that are more similar appear closer together in the diagram. We also used PRIMER to calculate average taxonom- ic distinctness (A"^) and variation in taxonomic distinctness (A"^) for all survey periods. These 2 statistics are sample size-independent measures of diversity where the taxo- nomic distance between every pair of species in a given assemblage is the basis for determining relative diversity (Warwick and Clarke 1995). More specifically, average taxonomic distinctness (A"^) is the mean taxonomic dis- tance apart of all species pairs in an assemblage, and vari- ation in taxonomic distinctness (A^) is the variance of the taxonomic distances between each species pair about their mean (Clarke and Warwick 2001). A detailed description of the properties that make these 2 statistics sample-size independent, and therefore useful for extracting meaning- ful information from simple presence-absence data, is pro- vided in Clarke and Warwick (2001). To calculate these statistics for each survey, the total list of species collected for all surveys was used. Based on classification from Nelson (1994), we identified the following taxonomic cat- egories for each species: species, genus, family, order, superorder, subdivision, division, subclass, class, and grade. Each of these categories represents a “node” in determining taxonomic distances between species pairs. We used this taxonomic species list in combination with the original presence-absence species data to run a TAXDTEST analysis in PRIMER. This analysis produces “funnel plots” where A"^ and A"^ for each survey are plot- ted in comparison with the mean and 95% confidence lim- its of A"^ and A"^ calculated for 1000 simulated matrices of presence-absence species data. Values of A"^ and A"^ for observed data that fall outside of the 95% confidence lim- its represent significant differences in diversity from expected. For this TAXDTEST analysis, the weighting option of using taxonomic richness was chosen. For this option, the weighting of inter-category distances is calcu- lated using the species richness information from the orig- inal presence-absence species data. Results A total of 107 fish species was collected during the 6 analyzed surveys (Table 1). Of these, 15 species occurred in every survey: Atlantic stingray {Dasyatis sabina), hard- head catfish (Arius felis), dark sea catfish (Cathoropus melanopus), Atlantic needlefish {Strongylura marina), shortfin molly (Poecilia mexicana), fat snook {Centropomus parallelus), fiagfin mojarra {Eucinostomus melanopterus), rhombic mojarra (Diapterus rhomb eus), Irish pompano {Diapterus auratus), striped mojarra (Eugerres plumieri), silver perch {Bairdiella chrysoura), whitemouth croaker {Micropogonias furnieri), white mul- let (Mugil curema), bay whiff {Citharicthys spilopterus), and lined sole (Achirus lineatus; Table 1). A total of 37 species were collected in only a single survey over the 6 150 Long-term fish assemblage dynamics TABLE 2 Frequency of species representing 4 ecological guilds (marine stenohaline, marine euryhaline, estuarine, and fresh- water) collected from the Alvarado Lagoon Estuary during 6 surveys conducted over 33 years (1968-2001). Survey Period Marine Stenohaline Marine Euryhaline Estuarine Freshwater 1966-1968 16 26 8 7 1987-1988 16 26 7 6 1989 7 24 8 4 1989-1990 12 31 9 6 1990-1991 15 30 8 6 2000-2001 9 29 13 9 survey periods. Of these, 15 species occurred only in the 1966-1968 survey and may have since become extirpated from the estuary: speckled worm eel {Myrophis punctatus), scaled sardine (Harengula jaguana), southern buffalo {Ictiobus meridionalis), skilletfish {Gobies ox strumosus), an unidentified silverside {Thyrinops [Atherinella] sp.), obscure swamp eel {Ophisternon aenigmaticum), Mexican snook (Centropomus poeyi), yellow jack (Caranx bartholomei), barred grunt (Conodon nobilis), silver seatrout {Cynoscion nothus), spotted seatrout {Cynoscion nebulosus). Jack Dempsey {Cichlasoma octo fas datum), blackstripe cichlid {Vieja fenestrata), highfin blenny (Lupinoblennius nicholsi), and hogchoker (Trinedes mac- ulatus){TsLb\e 1). When these species were divided into ecological guilds, marine euryhaline species dominated the Alvarado Lagoon Estuary during all survey periods (Table 2). The mean number of marine euryhaline species collected across the 6 surveys was 27.67 species (range = 24-31), Figure 2. Non-metric multidimensional scaling (MDS) dia- gram of fish species assemblage differences among the 6 fish surveys. Distances in diagram represent relative Bray-Curtis similarity values. Assemblages closer to each other are more similar. Representation of assemblage relationships is at the highest level of accuracy (stress = 0.01). whereas marine stenohaline, estuarine, and freshwater species averaged 12.50 (7-16), 8.83 (7-13), and 6.33 (4-9) species, respectively (Table 2). The occurrence frequency of fish species representing each ecological guild, though, did not change significantly among the survey periods. The chi-square deviation statistic calculated for the observed matrix ( ^ = 8.53) was not significantly larger than the mean value for 1000 simulated matrices ( ^ = 138.64; P = 1.00). The number of species representing each guild did not differ significantly from average over the 6 survey peri- ods. A non-metric multidimensional scaling (MDS) dia- gram based on Bray-Curtis similarities of fish species pres- ence-absence data showed that the 1966 survey period was the least similar to the other survey periods (Figure 2). The assemblage representing the 2000-2001 survey period was somewhat separated from the 1987-1988, 1989-1990, and 1990-1991 surveys, but this separation was similar to the degree of separation from these surveys exhibited by the 1989 survey period (Figure 2). For the 1966-1968 survey, the range of Bray-Curtis inter-survey similarities was 40.4-58.6 {n = 5; Table 3). By comparison, the remaining range of inter-survey similarities was 61.5-81.7 {n= 10; Table 3). Average taxonomic distinctness (A"^) and variation in taxonomic distinctness (A"^) for all survey periods were within the simulated 95% confidence limits for expected values (Figures 3 and 4). Both the and A"^ values for the 2000-2001 survey period, though, were less than the mean A"^ and A"^ values for the entire species pool (Figures 3 and 4). The only other values that were less than average (and only slightly) were the A"^ values for the 1987-1988, 1989, and 1990-1991 survey periods (Figure 3). Discussion Fish assemblages in the Alvarado Fagoon Estuary have not changed significantly over the last 40 years. This 151 ChAvez-Lopez et al. TABLE 3 Bray-Curtis inter-survey similarities for fish assemblages collected during 6 survey periods from the Alvarado Lagoon Estuary. Bray-Curtis indices typically range from 0-100 with higher values representing greater similar- ity between assemblage pairs. Survey Period 1966-1968 1987-1988 1989 1989-1990 1990-1991 2000-2001 1966-1968 - - - - - - 1987-1988 50.0 - - - - - 1989 40.4 70.1 - - - - 1989-1990 56.6 73.9 69.4 - - - 1990-1991 58.6 78.9 67.3 81.7 - - 2000-2001 55.5 61.5 61.5 64.4 72.7 - conclusion, though, needs to be considered in context of the loss of several species since 1966-1968 and an appar- ent more recent (since 1991) overall decline in biodiversi- ty in this ecosystem. Unfortunately, the highly variable nature of estuarine ecosystems precludes simple diagnoses of significant changes in fish assemblages (O’Connell et al. 2004). In these ecosystems, inter-habitat movement, especially by migrating estuarine fishes, creates temporal- ly dynamic fish faunas that are difficult to accurately assess without complete long-term data (Thompson and Fitzhugh 1985; Peterson and Ross 1991; Poff and Allan 1995). While the data and analyses presented here cannot definitively show a statistically significant change in fish- es relative to ecological guilds or assemblages, the results suggest past and potentially future ecological changes in the fishes of this estuary. The consistent occurrence of marine euryhaline fishes in collections over time reflects the salinity-tolerant nature of this ecological guild. Of the group of 15 species that were collected from all 6 surveys, 12 were marine euryha- line. The remaining 3 species consistently collected were C. melanopus (estuarine/freshwater), P. mexicana (fresh- water), and E. plumieri (marine stenohaline). Marine eury- haline fishes were the most suited to withstand the variety of events that have influenced the hydrological dynamics of Alvarado Lagoon Estuary since 1966. An artificial inlet Number of species Figure 3. Average taxonomic distinctness (A+) of fish assemblages collected during the 6 surveys relative to the mean A+ (dot- ted line) and the 95% confidence intervals (solid lines) for 1000 simulated fish assemblages. Simulated fish assemblages were generated from a total species list representing all fishes collected over all surveys. 152 Long-term fish assemblage dynamics was opened in Camaronera Lagoon in 1979 with hopes of increasing the salinity in this area of the system to increase shrimp production. Rosales-Hoz et al. (1986) reported a change from 4 to 25 psu in Camaronera Lagoon after the opening of the artificial inlet. Villalobos et al. (1975) found that discharge from the rivers was the principal influence on the hydrological and salinity patterns in the 1960s. Stratification of the system occurred from the estuarine zone of the Papaloapan River to the central region of the Alvarado Lagoon. The lagoon was almost entirely oligoha- line in the 1960’s, with slight salinity increases provided by the tides during the dry season. In contrast, during the 1980s, the majority of Camaronera Lagoon was mesoha- line (Raz-Guzman et al. 1992). The artificial inlet at Camaronera Lagoon was dredged in 1990, but by 1996 excessive sedimentation began, greatly restricting the cir- culation of marine waters into the lagoon. An El Nino event in 1998 resulted in increased freshwater inflow into the lagoonal ecosystem, as was reported for other coastal lagoons (Garcia et al. 2001, Kupschus and Tremain 2001, Mol et al. 2001). Thus, during this time period a large part of the lagoonal ecosystem had oligohaline and freshwater characteristics, with mesohaline conditions only found in the dry season near the inlets. These conditions were sim- ilar to those reported in the 1960s (Resendez 1973; Villalobos et al. 1975). Given this variability, marine eury- haline fishes have a considerable advantage over fishes in the other 3 ecological guilds. Neither freshwater nor marine stenohaline fishes could consistently withstand such changes in salinity. Estuarine fishes, though capable of tolerating a wide range of salinities, would be more prone than marine euryhaline species to local anthro- pogenic disturbances such as the opening of the artificial inlet and subsequent dredging. The entirety of their life cycles occurs in closer proximity to these impacts than marine euryhaline fishes. A similar response was seen in the Eake Pontchartrain Estuary, another degraded Gulf of Mexico ecosystem. Atlantic croaker {Micropogonias undu- latus), an estuarine species, experienced relatively greater declines than other fishes during a period of increased local shell dredging. More transient marine species that used the estuary less frequently, though, were not as impacted (O’Connell et al. 2004). The 15 fish species that were never collected after the 1966-1968 survey reflect the extent to which Alvarado Lagoon Estuary has changed over nearly 3 decades of mul- tiple anthropogenic impacts. By comparison, the degraded Eake Pontchartain Estuary lost only 3 species between 1954 and 2000 (O’Connell et al. 2004). While some of these “losf ’ species may be fishes that under normal con- ditions rarely occur in the estuary (e.g., there was a total of 37 species that were collected in only a single survey), it is Number of species Figure 4. Variation in taxonomic distinctness (A+) of fish assemblages collected during the 6 surveys relative to the mean A+ (dotted line) and the 95% confidence intervals (solid lines) for 1000 simulated fish assemblages. Simulated fish assemblages were generated from a total species list representing all fishes collected over all surveys. 153 ChAvez-Lopez et al. noteworthy that the survey with the most of these single occurrences was 1966-1968 (Table 1). The fact that this group of 15 single-occurrence species contains members of all 4 ecological guilds (6 marine stenohaline, 3 marine euryhaline, one estuarine, and 5 freshwater) suggests no single cause can explain the possible extirpations. For example, the loss of the freshwater cichlid species C. octo- fasciatum and V.fenestrata would more likely be related to habitat alteration in nearby rivers, while the absence of marine stenohaline species such as H. jaguana and C. bartholomei in later surveys may reflect responses to local salinity changes. This loss of species over time was not enough to sig- nificantly change the occurrence frequency of species in each of the 4 guilds. The marine euryhaline guild consis- tently had the greatest species representation in the Estuary while the number of species for the remaining 3 guilds fluctuated at lower species numbers; the highest number of non-marine euryhaline species in any one survey period was 16 (marine stenohaline in 1966-1968 and 1987-1988) while the lowest number of marine euryhaline species in any one period was 24 in 1989. A lack of significant change over time in the numbers of species in these guilds reflects the stability and tolerance of the dominant group, the marine euryhaline species. Whether natural or anthro- pogenic factors are influencing fish assemblages, the eco- logical guilds that will respond most closely to the impacts in this estuary happen to possess fewer species. Thus, if and when degradation starts to affect fishes, we should not expect to notice a significant change by examining the sys- tem using a broad-scale approach such as comparing eco- logical guilds. Had we discovered significant changes at this level of analysis, we could assume a much more severe impact had affected this ecosystem. Using the more precise approach of MDS, though, we developed a clearer understanding of how similar the sur- veys were to each other and how this loss of species affect- ed the assemblages. In the MDS diagram (Figure 2), the 1966-1968 survey clearly stands apart from the other 5 surveys and this is supported by the Bray-Curtis similarity index data (Table 3). The long horizontal “leap” from the single survey on the left of the diagram to the clump of sur- veys on the right indicates the largest assemblage change occurred between the 1966-1968 and 1987-1988 survey periods (Clarke and Warwick 2001). For the 5 more recent surveys, it appears that the estuarine assemblages have reached a new compositional “mean” and any assemblage changes since 1987 seem centered about this mode. This “cyclicity” (Matthews 1998) in later surveys implies 2 sit- uations: 1) recent assemblages have stabilized at a species compositional mode that is different from 1966-1968 and 2) recovery to an assemblage like that collected in the 1966-1968 survey is unlikely without massive restoration efforts. It should also be noted that within the cyclicity of the later 5 surveys, the 1989 and 2000-2001 surveys appear the furthest from the implied mode (in the diagram, 1989 is below the mode, 2000-2001 is above). While these positions might only reflect annual differences in species composition (e.g., a low rainfall year attracting more marine stenohaline fishes into the estuary), the position of the 2000-2001 assemblage may reflect the beginning of yet another compositional shift as occurred between 1966-1968 and 1987-1988. Further surveys could confirm whether the estuarine fish assemblage has stabilized (i.e., exhibits cyclicity) or is changing again (i.e., moving away from the recent compositional mode). When compared with the other 5 surveys, the and values for the 2000-2001 period indicate that assem- blage diversity is decreasing, though the change is not yet significant (Figures 3 and 4). In the funnel plot diagrams this latest survey is the only period where both and A"^ values are less than the calculated overall mean values (Figures 3 and 4). The implication is that the estuarine assemblage is at the beginning stages of yet another com- positional change that involves the loss of species diversi- ty. The relatively (though not significantly) depressed A"^ value for the 2000-2001 period translates into an assem- blage that is less taxonomically diverse than the other assemblages (e.g., fewer species per genus, fewer genera per family, etc.). Measuring and comparing A"^ (which is the variation of A"^) allows for an even finer analysis of rel- ative diversity. It is possible that 2 assemblages will have similar A"^ values even when one has mostly species-rich genera while the other has many higher taxa (e.g., families, orders, etc.) represented by only one or a few species (Clarke and Warwick 2001). Therefore, when both A"^ and A"^ values are relatively low (as for the 2000-2001 period) it suggests a reduction in both the normal array of higher taxa (reduced A"^) and a loss of those higher taxa with only a few representative species in the assemblage (reduced A"^). As with the MDS results, the fact that this latest sur- vey reflects a unique situation of lowered diversity relative to previous surveys should raise concerns that the fish assemblage in Alvarado Fagoon Estuary may once again be irreversibly transforming to another compositional mode. This work represents one of relatively few published studies on fish assemblages from the southern Gulf of Mexico (Castaneda and Contreras 1994). Information on species composition from other coastal lagoons and estu- aries in Mexico shows that the Alvarado Fagoon Estuary is typical, with only 3 other lagoon systems possessing high- 154 Long-term fish assemblage dynamics er fish diversity (Castaneda and Contreras 1994; Perez- Hernandez and Torres-Orozco 2000; Raz-Guzman and Huidobro 2002). In general, the Gulf of Mexico in this region is subjected to a variety of impacts, particularly the region in south-central Veracruz. Oil and gas exploration began on the continental shelf off Alvarado in 2000 and has since moved steadily closer to the lagoon ecosystem. Population growth, changes in land use practices, an increase in the cattle industry, and unregulated fishing have negatively impacted the lagoon ecosystem, which has resulted in the disappearance of valuable habitats for fish- es. Furthermore, large-scale climatic phenomena like El Nino effects and Global Warming (Blaber 2002, Whitfield and Elliot 2002) have influenced the hydrological charac- teristics of the system as well. The combination of these effects will no doubt continue to result in the deterioration of the integrity of the habitats of the lagoon system and the species that occupy them. Thus, this study documenting changes in assemblage composition of fishes over a 40- year period may be an important baseline data for future comparisons documenting additional anthropogenic changes in the Alvarado Lagoon Estuary. Acknowledgments The authors offer special thanks to N.J. Brown- Peterson for translating this paper from Spanish and M.S. Peterson and N.J. Brown-Peterson for their comments and suggestions. Graduate students C. Hurtado, I. Sayago, G. Gonzalez, and our colleagues J. Montoya, C. Bedia, A. Rocha, and A. Ra mir ez helped collect the biological mate- rial from the Alvarado system. 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Terms of reference towards an integrated management policy in the coastal zone of the Gulf of Mexico and the Caribbean. Ocean & Coastal Management 42:345-368. 156 Gulf and Caribbean Research Volume 17 Issue 1 January 2005 Trophic Relationships of Demersal Fishes in the Shrimping Zone Off Alvarado Lagoon^ Veracruz^ Mexico Edgar Pelaez-Rodriguez University of Southern Mississippi Jonathan Franco-Lopez Universidad Nacional Autonoma de Mexico Wilfredo A. Matamoros University of Southern Mississippi Rafael Chavez-Lopez Universidad Nacional Autonoma de Mexico Nancy J. Brown-Peterson University of Southern Mississippi, nancy.brown-peterson(® usm.edu DOI: 10.18785/gcr.l701.16 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Pelaez-Rodriguez, E., J. Franco-Lopez, W. A. Matamoros, R. Chavez-Lopez and N. J. Brown-Peterson. 2005. Trophic Relationships of Demersal Fishes in the Shrimping Zone Off Alvarado Lagoon, Veracruz, Mexico. Gulf and Caribbean Research 17 (l): 157-167. Retrieved from http://aquila.usm.edu/ gcr/voll7/issl/ 16 This Article is brought to you for free and open access by The Aquila Digital Community It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf and Caribbean Research Vol 17, 157-167, 2005 Manuscript received November 22, 2004; accepted February 4, 2005 TROPHIC RELATIONSHIPS OF DEMERSAL FISHES IN THE SHRIMPING ZONE OFF ALVARADO LAGOON, VERACRUZ, MEXICO Edgar Pelaez-Rodriguez, Jonathan Franco-Lopez, Wilfredo A. Matamoros^*, Rafael Chavez-Lopez, and Nancy J. Brown-Peterson^ Laboratorio de Ecologia, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autonoma de Mexico, Av. De los Barrios No 1, Los Reyes Iztacala, Tlalnepantla, Mexico C.P. 54090 A.R Mexico Corresponding author: Department of Biological Sciences, The University of Southern Mississippi, Box 5018, Hattiesburg, Mississippi 39406-5018, and ^Department of Coastal Sciences, The University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, Mississippi 39564 USA ABSTRACT The diet of demersal piscivorous fishes captured as bycatch of the commercial shrimping fleet off the Alvarado lagoonal system, Veracruz, Mexico, was studied. Nine collections distributed throughout the nortes (windy), wet, and dry seasons were made from November 1993 to January 1995. Sampling yielded a total of 646 fishes representing 10 families and 14 species, of which 44.9% had empty digestive tracts and were excluded from analysis. Trichiurus lepturus and Synodus foetens were the most abundant demersal predators in the collections. Differences in food consumption of the 7 most abundant predators were observed among the 3 seasons, with the greatest variety of prey (20 species) taken during the nortes season and the lowest variety (9 species) during the dry season. Five distinct trophic guilds were determined based on an index of relative importance of prey. Prey type and location of prey within the water column helped determine guild classification. The occurrence of different trophic guilds may allow for decreased competition for food resources on the continental shelf off Alvarado, Mexico. RESUMEN Se estudio la dieta de los peces piscivoros demersales capturados como fauna acompanante del camaron en la flota de barcos camaroneros del sistema de lagunas de Alvarado, Veracruz, Mexico. Se obtuvieron nueve cole- cectas que abarcaron las temporadas de nortes, Iluvias y secas desde noviembre de 1993 hasta enero de 1995. Las muestras produjeron un total de 646 peces representados por 10 familias y 14 especies; 44.9% fueron encantrados con el tracto estomacal vacfos y no fueron analizados. Trichiurus lepturus y Synodos foetens fueron los depredadores demersales mas abundantes en nuestras muestras. Se observaron diferencias en el consumo de alimen- to en las tres temporadas. La temporada de nortes mosh'o la mayor variacidn de presa (20 especies), y la menor variacidn se observd en la temporada de secas (9 especies). Cinco distintivos gremios troficos fueron identificados basados en el indice de importancia relativa de la presa. El tipo de presa y la localizacion de las presas en la colum- na de agua permitieron determinar la clasificacidn de los gremios. La existencia de diferentes gremios troficos per- mite una disminucidn en la competencia por recursos alimenticios en la plataforma continental del Alvarado, Mexico. Introduction Shrimp trawling is one of the most important fishing industries in Mexico. In the southern Gulf of Mexico off Veracruz, a serious decline in the Mexican shrimping industry was observed from 1980 to 1991. In 1980, the shrimping industry reported a production of 5000 metric tons/year of penaeid shrimp (Grande and Diaz 1981), whereas in 1991 production using the same capture effort was only 1500 metric tons/year (SEMARNAP 1997). Currently, catches oscillate between 2000 and 3000 metric tons/year off Veracruz (Uribe-Marinez 2003). Worldwide, overfishing both by commercial and recreational fishers has reduced the abundance and biomass of apex predator species (Tegner and Dayton 1999, Jackson et al. 2001, Coleman et al. 2004) as well as non-targeted species (Burrage et al. 1993, Steele et al. 2001), leading to altered food webs in estuaries, coral reefs, and kelp forests (Jackson et al. 2001). Data from several localities of the world show that in some types of fisheries more than 90% of the total catch (biomass) is discarded as waste bycatch (Alverson et al. 1994, Erzini et al. 2001, Kennelly and Broadhurst 2002). Studies have shown that the fish to shrimp ratio in temper- ate and subtropical areas of Mexico is 5:1 metric tons/yr, while the ratio in tropical areas is 10:1 metric tons/yr (Grande and Diaz 1981). Eurthermore, shrimp trawling disturbs extensive areas of benthic habitat, affects the ben- thic macrofauna, and dramatically changes the diversity and abundance of demersal fish fauna (Alverson et al. 1994, Kaiser 1998, Rogers et al. 1999). Eittle is known about the trophic structure and other ecological processes of the biotic community in the shrimping area off the Alvarado Eagoon, Veracruz, Mexico. This study was designed to examine the abun- dance and trophic interactions of demersal predatory fish- es that are part of the bycatch in this area of high shrimp trawling effort. A common method of establishing trophic 157 PelAez-Rodriguez et al. structure is by the determination of trophic guilds (Luczkovich et al. 2002). Trophic guilds, defined as the grouping of species that share similar resources in a com- petitive complex (Root 1973, Blondel 2003), were deter- mined in this study through analysis of stomach contents of trawl-caught fishes. Methods Study Area The study area is located immediately offshore of the Alvarado Lagoon system in the central portion of the state of Veracruz, Mexico, between 18°45'N, 95°40'W and 19°00'N, 95°42'W. Three well defined seasons character- ize the region: the wet season from June through September, the nortes (windy) season from October through January, and the dry season from February through May (Contreras 1985). Highest precipitation occurs during the rainy season and oscillates between 1 100-2000 mm over the year (Garcia 1973). The Alvarado area is characterized by extensive coastal vegetation including mangroves and seagrasses and a series of lagoons and rivers that brings considerable fresh water and organic matter to the continental shelf, particularly during the rainy season. Sample collection and processing We collected demersal fishes, known from the litera- ture to be piscivores, from boats of the Alvarado shrimping fleet on 9 occasions from November 1993-January 1995, covering all 3 seasons. There were 4 collections during the nortes season, 3 collections during the wet season and 2 collections during the dry season. Boats in the fleet were equipped with a 20 m beam trawl with a 5.5 m mouth opening that was constructed with 3.85 cm mesh. Towing speed was 5-6 km/h, covering a distance of 1.8-18.5 km per sampling event. Fishing depths ranged from 30-90 m, with a mean depth of 50 m. A 30 1 subsample of the bycatch (representing 25-27 kg of fish) was obtained using the methods described by Guzman (1991) and Pelaez-Rodriguez (1993) from trawls fished for 4 h between 0800-0730 local time (Central Time Zone). Formaldehyde (10%) was injected into the oral and anal areas and then fish were immersed in the formalde- hyde solution (Laevastu 1971). Fishes were labeled, bagged, and transported to the laboratory where samples were rinsed with tap water and preserved in 70% methanol within 48 to 72 hours. Species were identified with Hoese and Moore (1977), Fisher (1978), and Castro-Aguirre (1978). Fish were measured (standard length, SL, mm) and weighed to the nearest 0. 1 g. Stomachs were extracted, and their contents were identified to the lowest possible taxon using hard parts such as otoliths, scales, jaw bones and cra- nial bones (Windell and Stephen 1978). Prey items were blotted with desiccant paper and weighed to the nearest 0.001 g; empty stomachs were noted but not included in the analysis. Stomach contents of the 7 most abundant predators captured were used for analysis. Prey items were classified as pelagic, benthic, or benthic-pelagic according to knowledge of their general occurrence within the water column (Carpenter 2002). Data analysis Abundance and biomass of the predator species were compared among seasons for each subsample with analy- sis of variance (ANOVA) and pairwise Sidak post-hoc tests to separate mean values if a significant F-test was deter- mined. Species richness (S) was determined seasonally based on the abundance of the demersal, predatory fishes captured. Additionally, percent contribution of each species in terms of abundance and biomass were calculat- ed by season. The importance of each prey species for each of the 7 most abundant fishes was evaluated by pooling data for each season and then calculating the index of relative importance (IRI; Pinkas et al. 1971), defined as IRI = %F(%N + %W), where %F - frequency of occurrence of a food item, %N - numerical percentage of a food item in the stomachs, and %W = percentage by volume of the food item in the stomachs (Pinkas et al. 1971). IRI values were standardized to %IRI for comparison (Cortes 1997). A Bray-Curtis dissimilarity matrix was calculated based on %IRI values, and this matrix was used to construct a dendrogram using the unpaired grouping mean average (UPGMA) method (Field et al. 1982). ANOVA was calcu- lated using SPSS (SPSS Inc, ver 11.5, Chicago, IL). Values were considered significantly different if P < 0.05. Results Predator abundance and seasonality Fourteen species of demersal fishes belonging to 10 families were collected during the study, yielding a total of 646 individuals with a total biomass of 54 kg (Table 1). The families Synodontidae (4 species) and Sciaenidae (2 species) contributed almost half of the total species. Of the total catch, only 362 fishes or 56.1% contained prey in their stomachs. Three species have not been previously reported for the Alvarado area; they include Rachycentron canadum, collected only during the nortes season, and Synodus poeyi and Trachinocephalus myops, reported for both the nortes and wet seasons (Table 1). Overall, 158 Trophic Relationships of Demersal Fishes off Alvarado TABLE 1 Composition of the demersal fish fauna collected from commercial shrimp nets off the Alvarado Lagoon system during the nortes, dry and wet seasons. Abbreviations are presented for the 7 most abundant species. Nortes Dry Wet Total Abundance Biomass Abundance Biomass Abundance Biomass Abundance Biomass Species (ind) (g) (ind) (g) (ind) (g) (ind) (g) Muraenidae Gymnothorax nigromarginatus 5 685.3 7 635.9 6 709.1 18 2030.3 Ophichthidae Myrophis punctatus Synodontidae 2 147.0 3 192.5 6 334.7 11 674.2 Synodus foetens (Syfo) 67 14811.7 32 3119.3 25 1761.0 124 19692.0 Synodus poeyi 25 868.4 32 717.2 57 1585.6 Trachinocephalus myops 8 369.4 15 849.8 23 1219.2 Saurida brasiliensis (Sabr) Fistulariidae 15 75.7 5 47.9 66 291.5 86 415.1 Fistularia tabacaria Priacanthidae 2 84.1 2 42.1 4 126.2 Priacanthus arenatus 15 1518.6 2 373.3 6 568.7 23 2460.6 Rachycentridae Rachycentron canadum Sciaenidae 2 1208.0 2 1208.0 Cynoscion arenarius (Cyar) 5 639.3 8 560.9 6 1100.6 19 2300.8 Cynoscion nothus (Cyno) Sphyraenidae 25 2316.5 13 619.5 22 1853.7 60 4789.7 Sphyraena guachancho (Spgu) Trichiuridae 5 586.0 10 445.5 13 1612.7 28 2644.2 Trichiurus lepturus (Trie) Scombridae 43 4154.0 19 1514.9 87 6700.5 149 12369.4 Scomberomorus cavalla (Scca) 31 540.0 6 1449.2 5 315.2 42 2304.4 Totals 250 28004.0 174 8958.9 291 16856.8 646 53819.7 Species collected 14 10 13 14 Trichiurus lepturus was the most common predator species captured during the study, with a total of 149 individuals, and was the dominant species during the wet season. Synodus foetens and Saurida brasiliensis were the second and third most abundant predatory fishes captured, while Cynoscion nothus, Scomberomous cavalla, Spyraena guachancho and C. arenarius rounded out the top 7 species (Table 1). The wet season showed the highest abundance of predatory fishes in the shrimp bycatch, but it ranked sec- ond in biomass, with 291 specimens and 17 kg. The nortes season accumulated the highest biomass of bycatch preda- tors, 28 kg, but occupied the second place in predator fish abundance with 250 specimens. The lowest values of abun- dance and biomass were found during the dry season with a total of 174 specimens that yielded 9 kg (Table 1). However, there were no significant differences among sea- sons for either abundance (ANOVA, ^2 6 ~ P - 0.100) or biomass (ANOVA, F2 5 = 0.95, F = 0.438), sug- gesting a relatively stable and constant bycatch of predato- ry fishes in the shrimp trawl fishery in the area. Seasonally, richness of predatory bycatch fishes was greater in the nortes season followed by wet and then dry seasons (Table 1); a similar pattern was seen in total abun- dance as well. Synodus foetens, T lepturus and S. brasilien- sis were important contributors numerically and/or in terms of biomass to the total species complement (Tables 1 and 2). Synodus foetens was first and T. lepturus second in the nortes and dry seasons in terms of abundance and biomass. In the wet season T. lepturus and S. brasiliensis were the first and 2nd most abundant species, whereas T. lepturus and C. nothus contributed more to biomass (Table 2). 159 PelAez-Rodriguez et al. TABLE 2 Percent contribution of abundant predatory fishes by season in terms of abundance and biomass in the shrimping zone off the Alvarado Lagoon, Veracruz, Mexico. Nortes Dry Wet Species Abundance Biomass Abundance Biomass Abundance Biomass Synodus foetens 26.80 52.89 30.48 34.82 8.59 10.45 Trichiurus lepturus 17.20 14.83 18.09 16.91 29.90 39.75 Cynoscion nothus 10.00 8.27 12.38 6.91 7.56 10.99 Scomberomorus cavalla 12.40 1.93 5.71 16.18 1.72 1.87 Saurida brasiilensis 6.00 0.27 4.76 0.53 22.68 1.73 Sphyraena guachancho 2.00 2.09 9.52 4.97 4.47 9.57 Cynoscion arenarius 2.00 2.28 7.62 6.26 2.06 6.53 Synodus poeyi 10.00 3.10 10.99 4.25 Priancanthus arenatus 6.00 5.42 1.90 4.17 2.06 3.37 Gymnothorax nigromarginatus 2.00 2.45 6.67 7.10 2.06 4.21 Trachinocephalus myops 3.20 1.32 5.15 5.04 Myrophis punctatus 0.80 0.52 2.86 2.15 2.06 1.99 Fistularia tabacaria 0.80 0.30 0.69 0.25 Rachycentron canadum 0.80 4.31 Predator size and diets The modal SL for S. foetens was smaller in the nortes season than in the dry or wet seasons, whereas modal SL for T. lepturus was largest during the wet season (Table 3). However, the range in sizes for these 2 species overlapped for all 3 seasons. The modal SL for S. guachancho was larger in the nortes season compared to the dry or wet sea- sons, and the size range for the nortes season did not over- lap with the other 2 seasons (Table 3). The remaining 4 predator size ranges and modal SL did not change much by season (Table 3). This suggests that potential ontogenetic diet shifts imbedded within seasons probably did not affect analyses of trophic spectrum. Twenty-four prey species, including 20 fishes, three decapod crustaceans, and one cephalopod, were identified from the stomach contents of the top 7 predators. Among the fish prey, Bregmaceros cantori and Microdesmus lanceolatus have not been previously reported from the shelf off Alvarado Lagoon (Table 4). For the 7 predator species, the lowest number of prey types consumed (9) occurred during the dry season, while the highest number of prey types (20) was found during the nortes season. Prey types varied among predators and changed seasonally (Table 4). Synodus foetens was the second most abundant preda- tory species overall and had the largest variety of prey, with a total of 17 taxa (Table 4). This species fed on the greatest diversity of prey during the nortes season, and its prey occurred throughout the water column (Figure 1). Fifty-one percent IRI of the prey was benthic and included TABLE 3 Summary statistics on fish standard length (range and mode, cm) by season for the 7 predators used in the diet analysis. Species Nortes Dry Wet Range Mode Range Mode Range Mode Sphyraena guachancho 29.3-34.2 30.0 16.5-19.1 18.0 18.0-20.8 19.0 Synodus foetens 12.3-21.7 18.0 20.6-35.7 29.0 17.6-43.5 32.0 Trichiurus lepturus 32.0-58.6 46.0 39.4-51.8 47.0 45.6-89.7 64.0 Cynoscion arenarius 18.5-23.4 20.0 17.5-19.40 18.0 18.5-24.6 21.0 Cynoscion nothus 15.6-19.0 17.0 14.2-18.0 16.0 16.2-21.6 19.0 Saurida brasiliensis 7.4-8.9 8.0 52-1.6 6.0 8.4-11.0 9.0 Scomberomorus cavalla 24.5-27.3 25.0 22.6-28.4 24.0 21.5-27.6 25.0 160 Trophic Relationships of Demersal Fishes off Alvarado TABLE 4 Seasonal food composition and %IRI for 7 demersal fishes off Alvarado, Veracruz. Species Nortes Dry Wet Prey type %IRI Prey type %IRI Prey type %IRI S. guachancho Anchoa hepsetus 68.44 Bregmaceros cantori 66.15 Anchoa hepsetus 22.02 Cynoscion nothus 1.82 Saurida brasiliensis 8.56 Saurida brasiliensis 57.6 Bregmaceros cantori 8.94 Loligo pealei 25.29 Loligo pealei 20.38 Saurida brasiliensis 15.34 Loligo pealei 5.46 S. foetens Anchoa hepsetus 21.17 Anchoa hepsetus 51.26 Saurida brasiliensis 19.36 Saurida brasiliensis 2.03 Upeneus parvus 48.74 Upeneus parvus 8.29 Upeneus parvus 12.92 Loligo pealei 19.33 Loligo pealei 7.44 Bregmaceros cantori 17.70 Harengula clupeola 14.55 Pristipomoides aquilonaris 1.76 Trachurus lathami 2.64 Diplectrum bivittatum 23.17 Micropogonias fumieri 2.99 Syacium gunteri 3.57 Pristipomoides aquilonaris 9.16 Trichiurus lepturus 6.24 Diplectrum bivittatum 8.57 Engyophrys senta 0.56 Symphurus plagiusa 1.46 Haemulon aurolineatum 3.14 Serranus atrobranchus 13.01 Eucinostomus gula 0.90 T lepturus Anchoa hepsetus 49.48 Upeneus parvus 33.28 Anchoa hepsetus 36.43 Upeneus parvus 15.11 Harengula clupeola 24.01 Upeneus parvus 1.19 Pristipomoides aquilonaris 13.72 Loligo pealei 42.71 Pristipomoides aquilonaris 1.49 Harengula jaguana 12.2 Diplectrum bivittatum 0.55 Harengula clupeola 5.85 Synodus foetens 0.23 Loligo pealei 2.43 Bregmaceros cantori 2.54 Farfantepenaeus sp. 1.21 Saurida brasiliensis 8.81 Cynoscion nothus 0.38 Myrophis punctatus 7.19 Loligo pealei 8.27 Farfantepenaeus sp. 32.89 C. arenarius Saurida brasiliensis 27.05 Upeneus parvus 76.21 Saurida brasiliensis 33.96 Upeneus parvus 35.47 Diplectrum bivittatum 23.79 Upeneus parvus 24.11 Pristipomoides aquilonaris 15.21 Loligo pealei 41.93 Loligo pealei 0.65 Farfantepenaeus sp. 21.62 C. nothus Pristipomoides aquilonaris 37.91 Bregmaceros cantori 95.49 Bregmaceros cantori 51.59 Bregmaceros cantori 31.92 Farfantepenaeus sp. 4.51 Saurida brasiliensis 20.41 Saurida brasiliensis 13.15 Trichiurus lepturus 6.05 Trichiurus lepturus 4.16 Farfantepenaeus sp. 21.94 Microdesmus lanceolatus 0.15 Loligo pealei 12.70 S. brasiliensis Bregmaceros cantori 78.42 Bregmaceros cantori 67.62 Bregmaceros cantori 75.16 Loligo pealei 21.58 Loligo pealei 32.38 Loligo pealei 24.84 S. cavalla Anchoa hepsetus 94.08 Anchoa hepsetus 69.67 Anchoa hepsetus 25.52 Bregmaceros cantori 5.92 Upeneus parvus 30.33 Diplectrum bivittatum 53.52 Loligo pealei 20.95 161 PelAez-Rodriguez et al. Nortes Syfo Sabr Cyar Cyno Spgu Trie Scca Figure 1. Percentage of prey occurring in the pelagic, benthic-pelagic, and benthic zones of the water column for 7 demersal fishes off the Alvarado Lagoon system, Veracruz, Mexico, during the nortes, dry, and wet seasons. Synodus foetens (Syfo), Saurida brasiliensis (Sabr), Cynoscion arenarius (Cyar), Cynoscion nothus (Cyno), Sphyraena guachancbo (Spgu), Trichiurus lep- turus (Trie), Scomberomorus cavalla (Scca). Sample size for each species in the figure by season is found in Table 1. 162 Trophic Relationships of Demersal Fishes off Alvarado Upeneus parvus. Diplectrum bivittatum, Pristipomoides aquilonaris, Eucinostomus gula, Micropogonias fumieri, Symphurus plagiusa, and S. brasiliensis. Species from the pelagic zone contributed 41.5 %IRI of stomach contents and included Anchoa hepsetus, Harengula clupeola, and Trachurus lathami. A smaller percentage of the diet, 10.5 %IRI, was composed of Loligo pealei and Haemulon aurollineatum from the benthic-pelagic zone. During the dry season, S. foetens fed about equally on A. hepsetus from the pelagic zone and on U. parvus, a bottom dweller. During the wet season, the diet of S. foetens was dominat- ed by benthic prey (80.6 %IRI) which included S. brasiliensis, D. bivittatum, T lepturus. U. parvus, P. aquilonaris, Engyophrys senta, Syacium gunteri, and B. cantori. The benthic-pelagic zone contributed 19.3 %IRI to the diet; the only prey was L. pealei (Table 4). Saurida brasiliensis was the smallest piscivorous pred- ator in the study and showed no differences in seasonal prey consumption (Table 4, Figure 1). This species also had the least diverse diet, with the benthic B. cantori accounting for 67-78 %IRI of the diet each season. A benthic-pelagic species, L. pealei, made up the rest of the diet (Table 4). Neither Cynoscion arenarius nor C. nothus consumed any pelagic prey during the course of this study (Figure 1). Both species had the greatest diversity of prey items dur- ing the nortes season. During both the nortes and dry sea- sons, > 80 %IRI of the diet was composed of benthic species such as U. parvus, Earfantepenaeus sp., P. aquilonaris, B. cantori, and S. brasiliensis, whereas the remaining diet was composed of the benthic-pelagic L. pealei (Table 4). The diet of C. arenarius was dominated by benthic species during the wet season, as was the diet of the congener C. nothus (Figure 1). While the 2 Cynoscion species fed within the same areas of the water column, there were differences in the prey they captured. For instance, B. cantori was an important component of the diet of C. nothus throughout the year, yet this prey was never eaten by C. arenarius (Table 4). Similarily, U. parvus dominated the diet of C. arenarius but was never taken by C. nothus (Table 4). Sphyraena guachancho consumed only 5 prey items, yet there was marked seasonal variation in the dominant prey items (Table 4). For instance, the pelagic A. hepsetus dominated the diet in the nortes season, while no pelagic species were consumed during the dry season when the benthic B. cantori dominated the diet (Table 4, Figure 1). During the wet season, benthic prey such as S. brasiliensis was dominant in the diet. Trichiurus lepturus was the most abundant predator species captured during the study and the only species to feed throughout the water column year round (Figure 1). During the wet season, benthic (48 %IRI) and pelagic (36.4 %IRI) species constituted the majority of the diet (13 species) of T. lepturus; prominent taxa included Earfantepenaeus sp., S. brasiliensis, and A. hepsetus (Table 4). In contrast, the pelagic species A. hepsetus, Harengula jaguana, and H. clupeola dominated the diet during the nortes season (67.5 %IRI). During the dry sea- son, T. lepturus fed on 3 prey species, one from each sec- tion of the water column. The benthic-pelagic L. pealei (42.7 %RI) dominated the diet (Table 4, Figure 1). Scomberomorus cavalla consumed only 5 prey types during the course of the study. The pelagic A. hepsetus dominated the diet during both the nortes (94.1 %IRI) and dry (69.7 %IRI) seasons and also accounted for 25 %IRI of the diet during the rainy season (Table 4). While benth- ic prey were taken throughout the year and dominated the diet in the rainy season (Figure 1), 5. cavalla fed on differ- ent benthic species during each season (Table 4). Species/season dietary patterns Five distinct trophic guilds were delimited (Figure 2). Fishes in feeding guild A consumed mainly pelagic prey like A. hepsetus, H. jaguana, and H. clupeola, whereas fish in guild B consumed not only pelagic species but transi- tioned to feeding on benthic-pelagic species like L. pealei (Figure 2). Fishes in guild C were characterized by feeding on a mixture of benthic-pelagic and benthic prey like Earfantepenaeus sp., S. brasiliensis, U. parvus, Myrophis punctatus, and L. pealei (Figure 2). Fishes in feeding guilds D and E tended to focus on more benthic prey like S. brasiliensis, Earfantepenaeus sp., U. parvus, and B. can- tori. In general, the species/season trophic patterns identi- fied by guild analysis did not follow clear patterns, most likely due to body size-mouth gape differences and to sea- sonal prey availability. For example, C. nothus, S. brasiliensis and C. arenarius exhibited no seasonal differ- ences in trophic guild, and C. nothus and C. arenarius were assigned to different guilds (Figure 2). This suggests minimal differences in prey across seasons for these species. In contrast, members of guilds A and B were com- prised of different species and seasons with no clear pat- terns (Figure 2). Some species/season diets clustered together, and others did not. It was clear, however, that some species shifted from pelagic to benthic prey with sea- son. For example, S. guachancho fed on pelagic species during the nortes and wet seasons but shifted to benthic prey during the dry season. However, the modal SL and size ranges for S. guachancho were virtually identical dur- ing the dry and wet seasons (Table 3), suggesting the sea- sonal shift in prey is not related to ontogenic feeding dif- 163 PelAez-Rodriguez et al. Pelagic prey Benthic prey 0.87 - w E w (0 '■B (0 ■f I* OQ 0.05 - Spgu(N) Syfo(D) Trie (N) Syfo (N) Scca (W) Cyar(W) Cyar(D) Sabr(N) Sabr(D) Cyno (W) Cyno(N) Scca (N) Scca (D) Trie (W) Spgu (W) Trie (D) Cyar (N) Spgu (D) Sabr (W) Cyno (D) Syfo (W) Species/season Figure 2. UPGMA cluster analysis of %IRI based on Bray Curtis dissimilarity index for 7 demersal fishes off Alvarado Lagoon Veracruz, Mexico. Sphyraena guachancbo (Spgu), Synodus foetens (Syfo), Trichiurus lepturus (Trie), Scomberomorus cavalla (Scca), Cynoscion arenarius (Cyar), Cynoscion nothus (Cyno), Saurida brasiliensis (Sabr). N = nortes season, W = wet season, and D = dry season. Letters indicate trophic guilds identified from the cluster analysis. ferences. Similarily, S. foetens and T. lepturus were found in 3 different guilds based on season, suggesting differ- ences in size may not be as important as other factors determining prey selection. Synodus foetens fed on pelag- ic, benthic-pelagic, and benthic prey during all seasons, and T. lepturus fed on pelagic and benthic-pelagic prey. These 2 species were the most abundant species examined during this study and contributed the highest portion of biomass. Discussion Stomach content analysis is used widely to determine food composition, feeding strategies, trophic position, energy flow of predator and prey (Hyslop 1980), trophic structure (Luczkovich et al. 2002), and trophic partitioning (Ross 1986). Our analysis indicates the examination of stomach contents of top carnivores is an excellent way to evaluate the relationship between predators and food source in the shrimp grounds of Veracruz, Mexico. The diets reported here for the 7 most abundant pred- ators are generally similar to previous reports (Naughton and Saloman 1981, Mericas 1981, Divita et al. 1983, Sheridan et al. 1984, Cruz-Escalona et al. 2005), with some notable exceptions. While fish (in particular A/ic/ioa) were important in the diet of T. lepturus in both this study and in the northern Gulf of Mexico (GOM) (Mericas 1981, Sheridan et al. 1984), the seasonal dominance of squid in the diet (42.7 %IRI during the dry season) has not been previously reported. The diets of both C. arenarius and C. nothus captured off Veracruz differed from previous reports for the species (Sheridan et al. 1984, Sutter and Mcllwain 1987) in that no pelagic prey were noted in the present study, while Anchoa was a major component of the diet of both species in the northern GOM (Sheridan et al. 1984). Furthermore, Bregmoceros, common in the diets of other predators captured in the present study, was not found in either Cynoscion species, although this prey species was previously reported as an important compo- nent of the diet (Sheridan et. al 1984). While the diet of S. brasiliensis was dominated by fish as expected, squid was a more important component of the diet of (21.5-31.3 %IRI) than the 9% frequency of occurrence previously reported by Divita et al. (1983). The predominantly pisciv- orous diet of S. foetens agrees with previous reports from the northern GOM (Divita et al. 1983) and the Veracruz, 164 Trophic Relationships of Demersal Fishes off Alvarado Mexico, area (Cruz-Escalona et al. 2005), although the complete absence of penaeid shrimp in the diet is in con- trast to reports from the northern GOM (Divita et al. 1983). Our results showed patterns of resource partitioning and indicated that the 7 most abundant species examined in our study had proportioned diets based on where in the water column their prey was found. This tendency towards resource partitioning coincides with findings by Abarca- Arenas et al. (2004), who found similar evidence of resource partitioning in the Alvarado area based on the entire fish community. Macpherson (1981) and Livingston (1982) stated that in a trophic system, resource partitioning always will be observed; the pattern can be observed at the temporal level or in some cases at the diel level, even when competition among species exists Five trophic guilds were clearly identified in our study based on the level of the water column in which the prey was obtained. Two guilds fed mainly on pelagic prey, 2 fed more on benthic prey, and one fed more on benthic-pelag- ic prey. Noteworthy is the large number of prey items con- sumed by the latter guild, demonstrating capacity to feed throughout the water column and to maintain generalist prey consumption habits. Formation of the guilds did not appear related to body size, but rather to prey availability. Based on stomach con- tents, prey selection varied among the 3 seasons. Sedberry (1983) studied a community of demersal fishes on the con- tinental shelf of the middle Atlantic Bight and also docu- mented seasonal prey-shifting that appeared to be inde- pendent of predator size. The dry season showed the fewest taxa of prey taken, and the nortes season showed the most. With predator abundance remaining constant year-round and prey sources varying, guild structure was most likely affected. Although measurements were not made of abundance and diversity of prey beyond those obtained via stomach contents, our results suggest that prey in the nortes and wet seasons are more diverse than prey in the dry season, thus affecting the trophic guilds (sensu Darnell 1961). Seasonal nutrient flux may influence prey availability in the study area and thus the structure of trophic guilds. Nutrients in the Alvarado Lagoon system are largely dependent upon influx from the Papaloapan River. The river deposits the largest amount of nutrients into the sys- tem during the wet and nortes seasons (Moran-Silva et al. 2005), resulting in higher productivity levels (Abarca- Arenas et al. 2004) and a general increase in the amount of exploitable resources in the system (Contreras 1985, Soberon and Yanez-Arancibia 1985). Thus, it was not a surprise that our study found the largest variety of prey and the highest abundance of predators during these 2 seasons. Anthropogenic factors can affect the guild structure as well. Shrimp trawling is an important commercial activity off Alvarado (Grande and Diaz 1981). The effects of by- catch removal on the local demersal fish community have not been measured; however, evidence suggests that large- scale fishing affects the structure of fish communities by reducing the abundance of prey and predators and by reducing the size of predators (Pope and Knights 1982, Rice and Gislason 1996, Jennings et al. 1998, Rogers et al. 1999). In the Alvarado area, information is lacking regard- ing fishing activities and the life history and ecology of piscivorous fishes and their prey; thus, it is difficult to esti- mate the effect of the shrimp fishery and its bycatch on the trophic dynamics of the area. However, intense fishing activity in tropical waters can cause reduction in species richness and dominance of the smaller targeted and non- targeted fishes in the assemblage (Rogers et al. 1999). Our data suggest that a similar reduction in larger species may have occurred near Alvarado. For instance, large, poten- tially commercially important species such as R. canadum, F. tabacaria, S. guachancho, and S. cavalla composed only 11% of the total bycatch. Dominance of S. foetens and T. lepturus, 2 non-target species with the greatest variety of prey, suggests trophic adaptability and generalization may be important in this heavily fished system. 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Handbook No. 3, Blackwell Scientific Publications, Oxford, England, p. 219-226. Yanez-Arancibia, A. 1985. Recursos demersales de alta diversi- dad en las costas tropicales: Perspectiva ecologica. In: A. Yanez-Arancibia, ed. Recursos pesqueros potenciales de Mexico: La pesca del camaron. Progreso Universidad de Alimentos. Instituto de Ciencias del Mar y Limnologia, Instituto Nacional de Pesca, Universidad Nacional Autonoma de Mexico, Mexico, p. 17-38. 167 Gulf and Caribbean Research Volume 17 Issue 1 January 2005 Selected Life-History Observations on the Cayman Gambusia^ Gambusia xanthosoma Greenfield, 1983 (Poeciliidae) Michael A. Abney Georgia Power Company Richard W Heard University of Southern Mississippi^ richard.heard(®usm.edu Chet R Rakocinski University of Southern Mississippi DOI: 10.18785/gcr.l701.09 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Abney, M. A., R. W. Heard and C. E Rakocinski. 2005. Selected Life-History Observations on the Cayman Gambusia, Gambusia xanthosoma Greenfield, 1983 (Poeciliidae). Gulf and Caribbean Research 17 (l): 107-111. Retrieved from http : //aquila.usm.edu/ gcr/ vol 1 7/iss 1 /9 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf and Caribbean Research Vol 17, 107-1 11, 2005 Manuscript received June 7, 2004; accepted December 10, 2004 SHORT COMMUNICATION SELECTED LIFE-HISTORY OBSERVATIONS ON THE CAYMAN GAMBU- SIA, GAMBUSIA XANTHOSOMA GREENFIELD, 1983 (POECILIIDAE) Michael A. Abney Richard W. Heard^, and Chet F. Rakocinski^ ^Georgia Power Company, Environmental Services Laboratory, 5131 Maner Road, Smyrna, Georgia 30080 USA ^Department of Coastal Sciences, The University of Southern Mississippi, Gulf Coast Research Laboratory, 703 East Beach Drive, Ocean Springs, Mississippi 39564 USA Introduction The Cayman gambusia (Gambusia xanthosoma Greenfield, 1983) is an uncommon species within the G. punctata species group, endemic to North Sound, Grand Cayman Island, BWI. Since the original description (Greenfield 1983) only phylogenetic information has been published and little is known of its habitat, feeding ecolo- gy, or reproductive life history (Wildrick and Greenfield 1985, Rauchenberger 1988). Originally described from a brackish-water (30 psu) mosquito control ditch, the species also occurred throughout marine mangrove habitat and inland saline ponds adjacent to North Sound, Grand Cayman Island (see Figure 1). Here we present informa- tion on the habitat, diet, reproduction, life history, and par- asites of the Cayman gambusia. Materials and Methods We made collections and recorded environmental data of Cayman gambusia during 4 separate collecting trips: August 1996, January 1997, June 1997, and August 1999 (Figure 1). We recorded water temperature (°C), salinity (psu), pH, sediment type (i.e., detritus, ironshore rock, mud, sand, silt) and submerged structure (i.e., mangrove roots) at the time of sampling. Samples of Cayman gambu- sia were taken using either a 4.7 m long, 3 mm stretch- mesh seine; a 47 x 25 cm wide, 1 mm mesh kicknet; or a 2.5 m diameter, 1 cm mesh cast net. Presence/absence observations were made in areas inaccessible to sampling gear. Specimens were fixed in 10% Formalin, labeled, and returned to the laboratory where they were transferred to 70% ethanol. We examined diet, reproductive characteristics, and parasites of preserved specimens from the Little Salt Creek collection made on 25 January 1997, the only collection with gravid specimens. All males were measured to the nearest 0.01 mm standard length (SL) and examined for maturity based on anal-fin morphology (Turner 1941). Males were considered mature if the formation of the gonopodium was complete. Figure 1. Locations of Cayman gambusia presence at Grand Cayman Island, BWI. 107 Abney et al. TABLE 1 Environmental variables recorded at the time of sampling for Cayman gambusia from each location between August 1996 and August 1999. n/a = not available. Location Date Salinity (psu) Temperature (°C) D.O. (mg/1) pH Depth (m) Cayman Kai 8-14-99 39.2 32.6 3.50 n/a 1.2 Duck Pond Cay 8-10-99 37.5 33.9 5.4 n/a 0.3 Little Salt Creek 1-25-97 36.7 25.6 3.93 n/a 0.5 Little Sound 8-13-99 n/a n/a n/a n/a 1.0 NW Mangrove- 1 8-12-99 38.2 32.1 4.5 n/a 0.8 NW Mangrove-2 8-12-99 37.1 31.6 2.36 n/a 0.8 Sea Pond 8-21-96 34.1 28.3 4.60 8.0 1.0 Sea Pond 1-15-97 25.9 29.4 8.42 9.1 1.0 West Bay 6-13-97 30.7 29.6 1.22 8.3 0.5 Developmental stages were determined according to Haynes (1995), wherein ova and embryos were classed into 1 1 distinct morphological stages. Maturity in females was determined by the presence of a blastodisc (stage 4) or later stage embryo. Embryos of each stage and somatic tis- sues were dried separately overnight at 60 °C and weighed to the nearest 0.01 mg. Total embryo dry weight was deter- mined by summing the dry weights of all embryos from stages 4 through 11. For each specimen, the mean embryo dry weight was determined by dividing the total embryo dry weight by the number of embryos in the brood. Reproductive allotment (RA), an index of the resources invested by an individual female into the production of a single brood, was estimated according to Reznick and Endler (1982). Digestive tract contents of mature females were identified to the order or class taxonomic level. Pearson correlations were performed among 4 female reproductive traits and somatic dry weight using SPSS software (SPSS 11.0). Somatic dry weight and all repro- ductive traits except mean stage were log^g transformed prior to analysis. Significance levels were adjusted for multiple testing using the Sequential Bonferroni correction (Peres-Neto 1999). A strong negative relationship between embryo weight and mean stage of development would indicate lecithotrophy (i.e., mother does not supplement pre-fertilization yolk nutrients during embryo develop- ment), whereas a slope of zero or a shallow slope would indicate some matrotrophy (i.e., mother supplements pre- fertilization yolk nutrients during embryo development). Results and Discussion Based on many collections made over the course of 4 extensive surveys of ponds throughout the Cayman islands. Cayman gambusia appears to be confined to the North Sound on the western end of Grand Cayman Island, near mangroves. Specimen collection was difficult due to dense mangrove prop roots and at most locations only presence/absence could be noted. Habitat was either near or within shallow (0. 5-1.0 m) fringing mangroves with muddy detritus substratum along the edges of North Sound and in associated mosquito control ditches and connected pond systems. Other fishes co-occurred including 2 poe- ciliid species. Cayman limia {Limia caymanensis) and Caribbean gambusia (G. puncticulata puncticulata), and various non-poeciliid species such as tarpon {Megalops atlanticus), hardhead silverside (Atherinomorus stipes), crested goby {Lophogobius cyprinoides), gray snapper {Lutjanus griseus), and sheepshead minnow (Cyprinodon variegatus). Based on the presence of many piscivorous wading birds (e.g., egrets, herons), avian predation was likely, although differences in the intensity of predation among locations and seasons were not known. Physico-chemical conditions varied among the 8 col- lection sites and between seasons (Table 1), probably due to habitats having variable direct or indirect connections to the relatively high salinity of North Sound. The salinity ranged from 25.9 to 39.2 psu, and water temperature ranged from 25.6 to 33.9 °C. Of the 36 males collected from Eittle Salt Creek on 25 January 1997, 28 were mature; SE of mature individuals ranged from 18.00 to 31.48 mm (x = 25.37 mm). Of the 58 females collected and dissected, 27 were gravid; SE of mature individuals ranged from 21.90 to 38.60 mm (x = 28.58 mm). Variation existed among gravid females in mean embryo dry weight (range 1.80-3.92 mg; X = 2.70), number of embryos per brood (range 1-11; X = 3.89) and RA (range 1.74-13.54; x = 8.27) (Table 2). 108 Life History of Gambusia xanthosoma TABLE 2 Variation in female reproductive traits based on 27 gravid Cayman gambusia specimens from Little Salt Creek on 25 January 1997. s^ = standard error. Minimum Maximum Mean ± s^ Standard length (mm) Tr% wm 28.58 + 0.77 Somatic dry weight (mg) 46.09 322.26 118.48+ 11.60 Mean stage 4 11 6.74 + 0.36 Mean embryo dry weight (mg) 1.80 3.92 2.70 + 0.11 Number of embryos 1 11 3.89 + 0.47 Total embryo dry weight (mg) 2.73 25.98 10.20 + 1.21 Reproductive allotment 1.74 13.54 8.27 + 0.50 None of the gravid females exhibited superfetation, (i.e., the presence of multiple, non-successive developmental embryo stages. Turner 1940). Somatic dry weight was cor- related with all 4 reproductive traits: larger females tended to have more and larger embryos at more advanced stages of development (Table 3). However, as a result of doing multiple statistical tests, only total embryo weight remained significantly related to somatic weight (adjusted P < 0.05) after Sequential Bonferroni corrections were applied. Total embryo weight was strongly correlated with the number of embryos present, even after correction. The lack of any detectable correlation between mean embryo weight and mean stage suggested the presence of matrotrophic provisioning (Table 3; r=0.1, P>0.25). However, because of the limited data available, the possi- bility of spatio-temporal variation in facultative matrotro- phy and in the amount of female provisioning still exists (Trexler 1985). Such facultative matrotrophy was observed in Caribbean gambusia (Abney and Rakocinski 2004) and Cayman limia (M.A. Abney, unpublished data). Diet Observations In addition to pollen grains and seed pods, 9 taxonom- ic classes representing 21 orders of prey groups were iden- tified from 27 females (Table 4). The Diptera was repre- sented by the subgroups Brachycera, including some Cyclorrhapha, and multiple species of Nematocera. The Hemiptera was represented by multiple taxa, including the family Naucoridae. Hymenopterans included wasps (Apocrita) and ants (Formicidae). Individual species iden- tified were the ischyrocerid amphipod Erichthonius cf. brasiliensis, the oniscid ispopod Littorophiloscia cf. cule- brae (Philosciidae) and the tanaid Hargeria rapax (Lep- tocheliidae). Benthic, pelagic, and terrestrial prey were often found within the same specimen suggesting an opportunistic and generalist feeding behavior, typical of gambusiines (Meffe and Snelson 1989). Parasite Observations Several helminth parasites were noted from 40 adult female Cayman gambusia (38 preserved, 2 fresh caught) at the Salt Creek site. The widely occurring and relatively non-host specific ectoparasitic monogenean, Neobene- denia melleni (MacCallum), was observed attached to the head of a Cayman gambusia collected 27 January 1997 (Bullard et al. 2000). The body cavity of one Cayman gambusia contained the third stage larva of Contracecum sp., a nematode whose adult stage occurs in the digestive tract of piscivo- rous birds seen during collections. At least 2 different TABLE 3 Correlations among female reproductive traits based on 27 gravid Cayman gambusia specimens from Little Salt Creek on 25 January 1997. All variables except Mean stage are correlated logjQ scale. Bold values indicate signif- icant before sequential Bonferroni correction; asterisks indicate significant after correction for multiple tests. Mean stage Mean embryo dry weight Number of embryos Total embryo dry weight Somatic dry weight 0.284 0.405 0.504 0.628* Mean stage -0.148 -0.056 -0.130 Mean embryo dry weight -0.285 0.043 Number of embryos 0.941* 109 Abney et al. TABLE 4 Digestive tract contents of 27 gravid Cayman gambusia collected from Little Salt Creek on 25 January 1997. Number of digestive tracts with prey frequency ranges are given. Prey Type Prey Frequency Range 1 2-4 5-10 10-100 100-250 250-500 Foraminiferida 2 15 5 2 Gastropoda spp. 1 1 Polychaeta spp. 3 1 Araneae 2 Prostigmata 4 Oribatida 3 Pseudoscorpiones 2 "Planktonic" Ostracoda 4 2 "Harpactacoid" Copepoda 2 1 1 Amphipoda 2 Decapoda 1 Isopoda 2 Stomatopoda (larvae) 2 Tanaidacea 2 Coleoptera 3 1 Diptera 3 11 1 Hemiptera 6 2 Hymenoptera 7 9 3 Orthoptera 2 Thysanoptera 1 Insecta 9 Osteichthyes 2 1 Pollen grain 1 Seed pod 6 species of digenean parasites, too immature to be identi- fied, were observed in the intestines of Cayman gambusia. Status Cayman gambusia is a distinctive poeciliid species that appears to be restricted to the central mangrove area of North Sound, Grand Cayman. Collections made over the course of 4 extensive surveys of ponds throughout the Cayman islands failed to produce this species from any other areas. This unique species of Gambusia is of special concern in light of its low prevalence and pressures imposed upon the mangroves of Grand Cayman, by both the threat of development as well as large catastrophic tropical storms that frequent this region. Acknowledgments A. Bullard, F. Burton, P. Bush, B. Johnson, S. LeCroy, J. McLelland and W. Price assisted with specimen collec- tion. We thank the Cayman Islands Department of Environment and Marine Conservation Board for allowing and facilitating collections, especially P. Bush and C. McCoy. This research was supported by the National Trust for the Cayman Islands. Additional support to MAA was provided by Sigma Xi and the University of Kentucky. Literature Cited Abney, M.A. and C.F. Rakocinski. 2004. Life-history variation in Caribbean gambusia (Gambusia puncticulata puncticulata, Poeciliidae) from the Cayman Islands, British West Indies. Environmental Biology of Fishes 70:67-79. Bullard, S.A., G.W. Benz, R.M. Overstreet, E.H. Williams Jr., and J. Hemdal. 2000. Six new host records and an updated list of wild hosts for Neobenedenia melleni (MacCallum) (Monogenea:Capsalidae). Comparative Parasitology 67:190-196. Greenfield, D.W. 1983. Gambusia xanthosoma, a new species of poeciliid fish from Grand Cayman Island, BWI. Copeia 1983: 457-464. no Life History of Gambusia xanthosoma George, D. and P. Mallery. 2000. SPSS for Windows Step by Step. A Simple Guide and Reference 9.0 Update. 2nd Edition. Allyn and Bacon Press, Boston, MA, USA, 357 p. Haynes, J.L. 1995. Standardized classification of poeciliid devel- opment for life-history studies. Copeia 1995:147-154. Meffe, G.K. and F.F. Snelson Jr. 1989. An Ecological Overview of Poeciliid Fishes. In: G.K. Meffe and F.F. Snelson, Jr., eds. Ecology and Evolution of Livebearing Fishes (Poeciliidae). Prentice Hall, Englewood Cliffs, NJ, USA, p. 13-31. Peres-Neto, PR. 1999. How many statistical tests are too many? The problem of conducting multiple ecological inferences revisited. Marine Ecology Progress Series 176:303-306. Rauchenberger, M. 1988. Historical biogeography of poeciliid fishes in the Caribbean. Systematic Zoology 37:356-365. Reznick, D.N. and J.A. Endler. 1982. The impact of predation on life history evolution in Trinidadian guppies (Poecilia retic- ulata). Evolution 36:160-177. Trexler, J.C. 1985. Variation in the degree of viviparity in the sail- fin molly, Poecilia latipinna. Copeia 1985:999-1004. Turner, C.L. 1940. Superfetation in viviparous cyprinodont fish- es. Copeia 1940:88-91. Turner, C.L. 1941. Morphogenesis of the gonopodium in Gambusia ajfinis affinis. Journal of Morphology 69:161-185. Wildrick, D.M. and D.W. Greenfield. 1985. A unique gambusiine karyotype and its relevance to the systematics of the Gambusia punctata species group. Copeia 1985:1053-1056. Ill Gulf and Caribbean Research Volume 17 Issue 1 January 2005 First Report of the Mayan Cichlid^ Cichlasoma urophthalmus (Gunther 1 862 ) Collected in the Southern Littoral Zone of Lake Okeechobee^ Florida Wilfredo A. Matamoros University of Southern Mississippi Keith D. Chin South Florida Water Management District Bruce Sharfstein South Florida Water Management District DOI; 10.18785/gcr.l701.10 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Matamoros, W. A., K. D. Chin and B. Sharfstein. 2005. First Report of the Mayan Cichlid, Cichlasoma urophthalmus (Gunther 1862) Collected in the Southern Littoral Zone of Lake Okeechobee, Florida. Gulf and Caribbean Research 17 (l): 113-115. Retrieved from http://aquila.usm.edu/ gcr/voll7/issl/ 10 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf and Caribbean Research Vol 17, 113-115, 2005 Manuscript received December 13, 2004; accepted January 3, 2005 SHORT COMMUNICATION FIRST REPORT OF THE MAYAN CICHLID, CICHLASOMA UROPHTHALMUS (GUNTHER 1862) COLLECTED IN THE SOUTHERN LITTORAL ZONE OF LAKE OKEECHOBEE, FLORIDA Wilfredo A. Matamoros^, Keith D. Chin^, and Bruce Sharfstein^ ^Department of Coastal Sciences, The University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, Mississippi 39564 USA, E-mail wilfredo.matamoros@usm.edu ^Lake Okeechobee Division, South Elorida Water Management District, 1480-9 Skees Road, West Palm Beach, Elorida 33411 USA. Email kchin@sfwmd.gov, bsharfs@sfwmd.gov Introduction The Mayan cichlid, Cichlasoma urophthalmus (Gunther 1862), is a native freshwater fish of tropical America. Its natural distribution ranges from southern Veracruz in Mexico to Nicaragua, including the entire Yucatan peninsula (Miller 1966, Kullander 2003). Mayan cichlids in their native region have been found in both fresh and brackish waters (Miller 1966). Several studies have documented their ability to thrive in a wide range of salinities (Martinez-Palacios et al. 1990, Chavez-Lopez et al. 2005) and water temperatures (Stauffer and Boltz 1994). Mayan cichlids generally prefer well-oxygenated habitats with deep, transparent water and submerged aquatic vegetation (Chavez-Lopez et al. 2005), but also have been observed to withstand virtual anoxia for more than two hours in the laboratory (Martinez-Palacios and Ross 1986). Their robustness has allowed this species to thrive in many different aquatic habitats in the south Florida region including Florida Bay (Loftus 1987), Naples on the west coast (Faunce et al. 2002), Lake Osbourne in West Palm Beach (Fuller et al. 1999), and as far north as Charlotte Harbor (A. Adams, pers. comm.. Mote Marine Laboratory, Sarasota, FL). It remains unclear how this species was initially introduced to Florida, but it is speculated that it was accidentally released from private aquariums. Loftus (1987) and Trexler et al. (2000) note that although initial densities of Mayan cichlids in Florida Bay fluctuated when first introduced, they have since reached higher numbers and have become established in that region. Here we report the collection of five juvenile Mayan cichlids in Lake Okeechobee, a large, shallow subtropical lake (26°60'N, 80°50'W) (Figure 1). These specimens were collected on 4 and 10 November 2003 in the southern lit- toral zone of Lake Okeechobee at a site off the southwest tip of Torry Island (26°42'N, 80°44'W). The lake stage of this densely vegetated area is highly variable. Nico (in press) reported a single collection of 16 juvenile Mayan cichlids in 2001 from a backwater area in the rim-canal along the NE portion of Lake Okeechobee (Figurel); an area that is hydrologically isolated from the lake proper, except for several navigation locks and water control struc- tures. Materials and Methods Five specimens were collected with a 1 m^ aluminum throw trap during fish surveys by the South Florida Water Management District (SFWMD). After deployment of the trap, vegetation was harvested using rakes, aquatic weed cutters, and/or manual removal of plants. Fish were col- lected with a 600 pm mesh “D-shaped” dip net. Net sweeps were repeated until six consecutive sweeps yielded zero fish. Fish were placed in plastic Whirl-Pak™ bags and kept on ice. Standard lengths (SL, mm, ± 0.01) were measured using a digital micrometer and specimens were weighed (wet weight, ± 0.0 Ig). Fish were then fixed in 10% formalin and then transferred to 70% ethanol. One specimen each was submitted to the Florida Museum of Natural History, Gainesville, Florida, and to the Ichthyology Museum at the University of Southern Mississippi. To assess diet, we removed and examined the digestive tracts of two additional specimens. Gut contents and prey items were identified to lowest possible taxonom- ic category. Results Cichlasoma urophthalmus specimens were collected and identified based on the following combination of char- acteristics: shape of body and snout, dark bands on body side, intense dark blotch at the caudal fin base, dorsal spine count of XV (range from XV-XVII), anal fin spine count of V (range is V-VI), and conical shape of teeth (identifi- cation verified by Nico). The range of fish {n = 5) collected was 18.71 to 34.94 mm (x = 25.07 mm SL) and wet weight ranged from 0.16 to 1.17 g (x = 0.51 g). Four of the five Mayan cichlids were collected from dense beds of Hydrilla verticillata, an exot- ic submerged aquatic plant (Havens 2003). The remaining individual was captured in a giant bulrush stand (Scirpus 113 Matamoros et al. Flncida, USA I SpMinorn I Figure 1: Map of Lake Okeechobee, Florida, noting collection sites of this study and those of Nico 2001. californicus). Other fish collected included the golden top- minnow (Fundulus chrysotus), bluefin killifish (Lucania goodei), flagfish {Jordanella floridae), eastern mosqui- tofish {Gambusia holbwoki), least killifish {Heterandria formosa), and sailfin molly (Poecilia latipinnd). Digestive tract analysis of two specimens (18.71 and 22.32 mm SL) yielded more than 99% detritus, fish scales the posterior half of an unidentified amphipod, and partial- ly digested remains of a terrestrial insect. Discussion Although the mode of introduction of Mayan cichlids in Florida cannot be determined conclusively, it is evident this species is capable of expanding its range. Mayan cich- lids were reported in southern Florida for the first time in 1983 from samples collected in Everglades National Park (Loftus 1987). It was determined from that study that Mayan cichlids were restricted to the Taylor Slough drainage basin; however, Shafland (1996) reported that Mayan cichlids had spread and become abundant in sever- al canals and rivers of southern Florida, including the C- 111, and the more northern C-7 canal. Faunce et al. (2002) have also reported Mayan cichlids in Naples, on Florida’s west coast, and further north and east in West Palm Beach. Opportunistic feeding behavior and a tolerance to a wide range of salinities are characteristics that may facili- tate the success of the Mayan cichlid in new habitats and enhance its spread into new locations in Florida. Arthington and Mitchel (1986) have suggested that this species is a generalist feeder. Bergman and Motta (in press) support this claim with fish collected from Big Cypress National Preserve concluding that the Mayan cichlid demonstrates a generalist diet throughout its ontogeny and primarily consumes detritus, vegetation, gas- tropods, crustaceans, insects, and fish. Caso-Chavez et al. (1986) and Chavez-Lopez et al. (2005) found that Mayan cichlids ate mostly plant material and supplemented their diet with crustaceans, insects, and mollusks. In contrast, in Mexico, the Mayan cichlid has been classified as a carni- vore because it appears to prey primarily on small animals (Martinez-Palacios and Ross 1988). 114 Mayan Cichlids in Lake Okeechobee The distribution and feeding ecology of the Mayan cichlid in Lake Okeechobee is largely unknown, although our limited gastro-intestinal tract analysis would seem to support generalist feeding behavior, at least for juveniles. The systematic collection of juvenile Mayan cichlids in the southern end of Lake Okeechobee, Nice’s (in press) col- lection from the NE rim-canal, and anecdotal accounts of captures by fishermen from widely distributed locations throughout Lake Okeechobee suggest this species is ubiq- uitous in the system. However, we have yet to observe any recruitment, spawning, or nesting behavior; key factors that define an established community (Loftus 1987). An adult Mayan cichlid was recently captured in the Kissimmee River, a major tributary that flows into the northwestern corner of the lake (L. Glenn, pers. comm., SFWMD, West Palm Beach, FL). To our knowledge, this is the most northern specimen collected in the Fake Okeechobee watershed. Further research on the potential impact of Mayan cichlids on native fish populations and its role in the troph- ic structure of Fake Okeechobee is warranted since the species appears to have the potential to become a common member of the littoral zone community. The distribution of invasive fish species such as the Mayan cichlid in south Florida is highly variable and is possibly a function of habitat preference, spatial relationship of sampling area to point of introduction, and ambient temperature changes (Trexler et al. 2000). For Mayan cichlids in the Everglades, Trexler et al. (2000) reported that annual minimum tem- perature affected species abundance, and that introduced species required time to expand from their point of intro- duction. Further investigation may provide insight into how and where the Mayan cichlid was introduced to Fake Okeechobee, and how to monitor and regulate its popula- tion growth. Acknowledgments We thank T. East for her assistance in the field and laboratory and A. Rodusky for his field assistance and review of this manuscript. Special appreciation is given to F.G. Nico and F. Glenn for their assistance in the identifi- cation of our specimens. Literature Cited Arthington, A.H. and D.S. Mitchel. 1986. Aquatic invading species. In: R.H. Groves and J.J. Burdon, eds. Ecology of Biological Invasions. Cambridge University Press, Sydney, Australia, p. 34-56 Bergmann, G.T. and P.J. Motta. (in press). Diet and morphology through ontogeny of the nonindigenous Mayan cichlid 'Cichlasoma (Nandopsis)’ urophthalmus (Gunther 1862) in southern Florida. Environmental Biology of Fishes. Caso-Chavez, M., A. Yanez-Arancibia, and A.L. Lara- Dominguez. 1986. Biologia, ecologia y dinamica de pobla- ciones de Cichlosoma urophthalmus (Gunther) (Pisces: Cichlidae) en habitat de Thalassia testudinium y Rhizophora mangle, Laguna de Terminos, sur de del Golfo de Mexico. Biotica 11:79-111. Chavez-Lopez, R., M.S. Peterson, N.J. Brown-Peterson, A.A. Morales-Gomez, and J. Franco-Lopez. 2005. Ecology of the Mayan cichlid, Cichlasoma urophthalmus Gunther, in the Alvarado lagoonal system, Veracruz, Mexico. Gulf and Caribbean Research 17(1):. Faunce, C.H., H.M. Patterson, and J.J. Lorenz. 2002. Age, growth, and mortality of the Mayan cichlid {Cichlasoma urophthalmus) from the southeastern Everglades. Fishery Bulletin 100:42-50. Fuller, P, F.G. Nico, and J.D. Williams. 1999. Nonindiginous fishes introduced to inland waters of the United States. American Fisheries Society, Special Publication 27, Bethesda, MD, USA, 620 p. Havens, K. 2003. Submerged aquatic vegetation correlations with depth and light attenuating materials in a shallow subtropi- cal lake. Hydrobiologia 493:173-186. Kullander, S.O. 2003. The Cichlids. In: R.E. Reis, S.O. Kuhander, and C.J. Ferraris Jr., eds. Check list of the fresh- water fishes of South and Central America. EDIPUCRS, Porto Alegre, Brazil. Loftus, W.F. 1987. Possible establishment of the Mayan cichlid, Cichlasoma urophthalmus (Gunther) (Pisces: Cichlidae), in Everglades National Park, Florida. Florida Scientist 50: 1-6. Martinez-Palacios, C.A. and F.G. Ross. 1986. The effects of tem- perature, body weight and hypoxia on the oxygen consump- tion of the Mexican mojarra, Cichlasoma urophthalmus (Gunther). Aquaculture and Fishery Management 17:243-248. Martinez-Palacios, C.A. and F.G. Ross. 1988. The feeding ecol- ogy of the Central American cichlid Cichlasoma urophthal- mus (Gunther). Journal of Fish Biology 33:665-670. Martinez-Palacios, C.A., F.G. Ross, and M. Rosado- Vallado. 1990. The effect of salinity on the survival and growth of juvenile Cichlasoma urophthalmus. Aquaculture 91:65-75. Miller, R.R. 1966. Geographical distribution of Central American freshwater fishes. Copeia 1966:773-802. Nico, F.G. (in press). Changes in the Fish Fauna of the Kissi mm ee River Basin, Peninsular Florida: Non-Native Additions. In: J.N. Rinne, R.M. Hughes, and B. Calamusso, eds. Historical changes in large river fish assemblages of America. Special Publication, American Fisheries Society Special Publication, Bethesda, MD, USA. Shafland, PL. 1996. Exotic fishes of Florida, 1994. Reviews in Fisheries Sciences 4:101-122. Stauffer Jr., J.R. and S.E. Boltz. 1994. Effect of salinity on the temperature preference and tolerance of age-0 Mayan cich- lids. Transactions of the American Fisheries Society 123:101-107 Trexler, J., W.F. Loftus, F. Jordan, J. J. Lorenz, J. H. Chick, and R.M. Kobza. 2000. Empirical assessment of fish introduc- tions in a subtropical wetland: an evaluation of contrasting views. Biological Invasions 2:265-277. 115 Gulf and Caribbean Research Volume 17 Issue 1 January 2005 Recent Observations of the Whale Shark (Rhincodon typus) in the Northcentral Gulf of Mexico Eric R. Hoffmayer University of Southern Mississippi James S. Franks University of Southern Mississippi^ jim.franks(®usm.edu John P. Shelley University of Southern Mississippi DOI; 10.18785/gcr.l701.11 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr & Part of the Marine Biology Commons Recommended Citation Hoffmayer, E. R., J. S. Franks and J. R Shelley. 2005. Recent Observations of the Whale Shark (Rhincodon typus) in the Northcentral Gulf of Mexico. Gulf and Caribbean Research 17 (l): 117-120. Retrieved from http://aquila.usm.edu/gcr/voll7/issl/l 1 This Short Communication is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf and Caribbean Research Vol 17, 117-120, 2005 Manuscript received December 20, 2004; accepted January 7, 2005 SHORT COMMUNICATION RECENT OBSERVATIONS OE THE WHALE SHARK {RHINCODON TYPUS) IN THE NORTHCENTRAL GULF OF MEXICO Eric R. Hoffmayer^, James S. Franks^, and John P. Shelley^ ^Center for Fisheries Research and Development, Gulf Coast Research Laboratory, and the ^Department of Coastal Sciences, The University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, Mississippi 39564 USA, E-mail eric.hoffinayer@usm.edu Introduction The whale shark {Rhincodon typus Smith, 1828) is the world’s largest fish, reaching 15 meters (m) and 18 metric tons (Colman 1997) and is found in all tropical and warm temperate seas (Compagno 2001). The whale shark is list- ed as ‘vulnerable’ by the International Union for the Conservation of Nature and Natural Resources (lUCN 2004) and is included in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES 2004). Tittle is known about whale sharks in the Gulf of Mexico (Gulf). Only reports on the occurrence of whale sharks off Texas (Baughman 1950, Baughman and Springer 1950, and Hoffman 1981) and accounts of the occurrence and feeding in the northcentral Gulf (Gudger 1939, Springer 1957) are available. Due to the lack of information on whale sharks in the Gulf, we developed a survey (http://www.usm.edu/gcrl/whale- shark_survey) to compile records of recent sightings and associated observations that are summarized here. Materials and Methods Details of whale shark sightings were obtained from recreational fishers, charter fishing operators, and divers by personal interview or the internet survey. Information requested from individuals who sighted whale sharks included date, location (e.g., GPS coordinates, direction and distance from a coastal landmark, or identifier number of specific offshore petroleum platforms), estimated total length (TF, ft), number of individuals, behavior (e.g., swimming, feeding), and associated fishes. Sightings greater than two years old were not included in the data- base unless sufficient documentation (e.g., log entry) of their validity was provided. Results Interviews provided information for 26 sightings involving 46 whale sharks between July 2002 and November 2004. Additionally, four large aggregations (30-100 individuals) of whale sharks were also reported; however, information reported for the aggregations was scant and not included in the data analysis. Nineteen sight- ings were of individual whale sharks, with seven sightings consisting of two to seven sharks. The seasonal distribu- tion and the number of whale sharks are shown in Figure 1. Sightings occurred in waters with depths from 20 to 1,000 m. Most whale sharks (80%) were observed swim- ming horizontally near the surface of the water, while the others were observed in vertical profile, apparently suc- tion-feeding on small prey. All observations occurred between May and November with 83% of the sightings occurring between July and October (Figure 2). There was a prevalence of sightings southwest of the Mississippi River Delta during summer and northeast of the Delta during the fall (Figure 1). Many sightings (63%) occurred at or near petroleum platforms (Figure 3). Estimated size (feet converted to meters) ranged from 3.7 to 10.7 m TF (n = 41, Figure 4). Gender was not noted. Ten teleost and two shark species were observed with whale sharks during 69% of the sightings (Table 1). Tunas were the most commonly reported, particularly blackfin, Thunnus atlanticus, skipjack, Katsuwanus pelamis, and yellowfin, Thunnus albacares. The authors and colleagues caught blackfin and skipjack tuna from large schools of tuna associated with two whale sharks in September 2002. Discussion The information reported here represents recent accounts of whale shark sightings in the northcentral Gulf. These data plus unpublished accounts (K. Mullins, NOAA Fisheries, Pascagoula Facility, per. comm.) suggest that whale sharks occur frequently in the northern Gulf during warmer months, entering the northcentral Gulf from the west or southwest in the late spring/early summer. They appear to move northeastward during the fall, and are per- haps absent during the winter. These apparent seasonal patterns are based only on surface observations. We assume there is no seasonal variability in vertical position of this species within the Gulf and thus no bias in these observations. Although whale sharks are considered to be 117 Hoffmayer et al. go-w j 63°W Mississippi Alabama Florida Louisiana 30"N' -30° N O Mississippi River Detia Legend 2e*N- Gulf of Mexico Number of Whale Sharks Fall Summer K3 X-2 • 1-2 3-g • 3-3 30-100 # 30-100 Spring Bathymetry 01020 40 60 80, hKI iiometers 3-9 30-100 0-200m 200-500nn 50O-25COm >3500m -23°N 90‘W as^w Figure 1. Locations of whale shark, Rhincodon typus, sightings in the northcentral Gulf of Mexico between 2002 and 2004. Some symbols may overlap due to the proximity of individual sightings. Only the smallest symbol for spring is shown. highly migratory throughout much of their range (Eckert and Stewart 2001), available data provide no insight into whether whale sharks in the northern Gulf are transient or comprise a resident population. Aggregations of whale sharks (up to 30 individuals) were previously reported in the northern Gulf (Gudger 1939; W. Driggers, NOAA Fisheries, Pascagoula Facility, per. comm.). The significance of whale shark aggregations is unknown, but Colman (1997) reported that aggregations may occur in areas with dense prey. The four large aggre- gations as well as the majority of other sightings reported here occurred at or near petroleum platforms, which func- tion as fish aggregating devices (Franks 2000). However, the predominance of sightings at petroleum platforms is likely attributable to the use of platforms as preferred recreational fishing destinations. Whale sharks themselves attract other fishes (Gudger 1941, Baughman and Springer 1950, Hoffman et al. 1981, Clark and Nelson 1997), and we report the highest diversity of pelagic fishes document- ed in association with whale sharks. Although most whale sharks in this study were observed swimming horizontally, it was not always evident that they were feeding. However, 20% of the whale sharks were observed suction-feeding while in vertical profile, similar to reports by Gudger (1941), Springer (1957) and Hoffman et al. (1981). Springer (1957) reported five whale sharks feeding vertically on small fishes in a school of blackfin tuna in the northcentral Gulf. Running-ripe male and female blackfin tunas caught during the author’s 2002 whale shark encounter regurgitated small clupeids on deck. However, we could not determine if the whale sharks were feeding on clupeids or the spawn of the tuna. Colman (1997) suggested that whale sharks and associated fishes may feed on the same prey, and Heyman et al. (2001) reported whale sharks feeding on snapper spawn, suggest- ing that this feeding behavior may also be occurring here. Seasonal distribution of whale sharks in the northcen- tral Gulf may be influenced by hydrologic/oceanographic features (e.g., Foop Current, Mississippi River plume, con- vergent zones, upwellings, temperature discontinuities). 118 Whale Shark Observations in Gule oe Mexico May June July Aug Sept Oct Nov Month Figure 2. Percent occurrence by month of whale sharks, Rhincodon typus, observed in the northcentral Gulf of Mexico from July 2002 to November 2004. Numbers above his- tograms indicate sample size, and numbers in parentheses indicate the number of sightings. Figure 3. An estimated 8 m whale shark, Rhincodon typus, near a sport fishing boat at a petroleum platform in the northcentral Gulf of Mexico on October 30, 2003. Such features provide optimal conditions for the produc- tion of plankton (Govoni et al. 1989, Richards et al. 1993), a food source of whale sharks (Colman 1997). These fea- tures also aggregate primary consumers such as crus- taceans, small fishes, and jellyfish which are also known prey of whale sharks (Gudger 1941, Colman 1997, Heyman et al. 2001), thereby creating spatially discrete feeding areas. Finally, Wilson et al. (2001) noted that whale sharks may time their seasonal movements to coin- cide with localized productivity events or behavioral changes in their prey. The individuals reported here ranged from 3.7 to 10.7 m TL and 56% appear to be immature as Joung et al. (1996), Beckley et al. (1997) and Wintner (2000) reported Size class (m) Figure 4. Length frequency plot of whale sharks, Rhincodon typus, observed in the northcentral Gulf of Mexico from July 2002 to November 2004. Numbers above histograms indicate sample size. that maturity occurs at 9.0 m TL and 10.5 m TL for males and females, respectively. These data, along with Baughman’s (1955) reported collection of an aborted whale shark egg case off Texas, imply that the Gulf may be a whale shark nursery area, as was suggested by Gudger (1939). Limited data are available on life history, movement, and habitat requirements of whale sharks in the northcen- tral Gulf. Furthermore, their designation as “vulnerable” by lUCN and their listing by CITES demonstrate the need for greater understanding of this species throughout its range. Hoffmayer et al. (in press) proposed a plan of research, which includes population surveys, biological assessments, and habitat use evaluation to advance the sci- entific understanding of whale sharks in the Gulf for the develop of future management plans and protection meas- ures for the species. Acknowledgments We extend our appreciation to numerous recreational fishers for their reports of whale shark sightings. Keith Mullin and W. Diggers (NOAA Fisheries, Mississippi Laboratories, Pascagoula Facility) and S. Schindler shared information on whale shark sightings in the Gulf. Kelly Lucas, A. Criss, K. Shultz, and M. Partyka assisted with development of the distribution map and T. Flowers pro- vided the image of the whale shark in Figure 3. We acknowledge our colleagues with the offshore Sargassum Project and the crew of the RV Tommy Monro. This work was supported in part by the Mississippi Department of Marine Resources, Mississippi Gulf Coast Billfish Classic, and Release Marine. 119 Hoffmayer et al. Literature Cited Baughman, J.L. 1950. Random notes on Texas fishes. Part I. Texas Journal of Science 2:117-138. Baughman, J.L. 1955. The oviparity of the whale shark, Rhincodon typus, with records of this and other fishes in Texas waters. Copeia 1955:54-55. Baughman, J.L. and S. Springer. 1950. Biological and economic notes on the sharks of the Gulf of Mexico, with especial ref- erence to those of Texas, and with a key for their identifica- tion. American Midland Naturalist 44:96-152. Beckley, L.E., G. Cliff, M.J. Smale, and L.J.V. Compagno. 1997. Recent strandings and sightings of whale sharks in South Africa. Environmental Biology of Eishes 50:343-348. CITES. 2004. Convention on International Trade in Endangered Species of Wild Eauna and Elora. http://www.cites.org. Clark, E. and D.R. Nelson. 1997. Young whale sharks, Rhincodon typus, feeding on a copepod bloom near La Paz, Mexico. Environmental Biology of Eishes 50:63-73. Colman, J.G. 1997. A review of the biology and ecology of the whale shark. Journal of Fish Biology 51:1219-1234. Compagno, L.J.V. 2001. Sharks of the world: an annotated and illustrated catalogue of shark species known to date. Volume 2: Heterodontiformes, Lamniformes, Orectolobiformes. FAO Species Catalogue for Fishery Purposes No. 1, Rome, Italy, 269 p. Eckert, S.A. and B.S. Stewart. 2001. Telemetry and satellite tracking of a whale sharks, Rhincodon typus, in the Sea of Cortez, Mexico and the north Pacific Ocean. Environmental Biology of Fishes 60:299-308. Franks, J.S. 2000. Pelagic fishes at offshore petroleum platforms in the northern Gulf of Mexico: Diversity, interrelationships, and perspective. Mechanisms and effects of the aggregation of tuna by fish aggregating devices (FADs). Peche thoniere et dispositifs de concentration de poisons, Colloque Caraibe-Martinique, Martinique, French West Indies, 28:502-515. Govoni, J.J., D.E. Hoss, and D.R. Colby. 1989. The spatial distri- bution of larval fishes about the Mississippi River plume. Limnology and Oceanography 34:178-187. Gudger, E.W. 1939. The whale shark in the Caribbean Sea and the Gulf of Mexico. Scientific Monthly 68:261-264. Gudger, E.W. 1941. The food and feeding habits of the whale shark {Rhincodon typus). Journal of the Elisha Mitchell Science Society 57:57-72. Heyman, W., R. Graham, B. Kjerfve, and R.E. Johannes. 2001. Whale sharks Rhincodon typus aggregate to feed on fish spawn in Belize. Marine Ecology Progress Series 251:275-282. Hoffman, W., T.H. Fritts, and R.P Reynolds. 1981. Whale sharks associated with fish schools off south Texas. Northeast Gulf Science 5:55-57. Hoffmayer, E.R., J.S. Franks, and J.P Shelley. In press. Whale sharks {Rhincodon typus) in the northcentral Gulf of Mexico: a rationale for research. Proceeding of the Gulf and Caribbean Fisheries Institute 57. lUCN. 2004. International Union for the Conservation of Nature and Natural Resources, http://www.redlist.org. Joung, S.J., C.T. Chen, E. Clark, S. Uchida, and W.Y.P Huang. 1996. The whale shark, Rhincodon typus, is a livebearer: 300 embryos found in one ‘megamamma’ supreme. Environmental Biology of Fishes 46:219-223. Richards, W.J., M. F. McGowen, T. Leming, J. T. Lamkin, and S. Kelly. 1993. Larval fish assemblages at the Loop Current boundary in the Gulf of Mexico. Bulletin of Marine Science 53:475-537. Springer, VJ. 1957. Some observations on the behavior of schools of fishes in the Gulf of Mexico and adjacent waters. Ecology 38:166-171. Wilson, S.T., J.G. Taylor, and A.F. Pearce. 2001. The seasonal aggregation of whale sharks at Ningaloo Reef, Western Australia: Currents, migrations, and the El Nino/ Southern Oscillation. Environmental Biology of Fishes 61:1-11. Wintner, S.P 2000. Preliminary study of vertebral growth rings in the whale shark, Rhincodon typus, from the east coast of South Africa. Environmental Biology of Fishes 59:441-451. 120 Gulf and Caribbean Research Volume 17 Issue 1 January 2005 Introduction to Special Section on Research Activities at the Iztacala Campus of the Universidad Nacional Autonoma de Mexico^ Mexico Mark S. Peterson University of Southern Mississippi^ mark.peterson(®usm.edu Nancy J. Brown-Peterson University of Southern Mississippi^ nancy.brown-peterson(® usm.edu DOI: 10.18785/gcr.l701.12 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Recommended Citation Peterson, M. S. and N. J. Brown-Peterson. 2005. Introduction to Special Section on Research Activities at the Iztacala Campus of the Universidad Nacional Autonoma de Mexico, Mexico. Gulf and Caribbean Research 17 (l): 121-121. Retrieved from http://aquila.usm.edu/gcr/voll7/issl/12 This Editorial is brought to you for free and open access by The Aquila Digital Community It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf and Caribbean Research Vol 17, 121, 2005 INTRODUCTION TO SPECIAL SECTION ON RESEARCH ACTIVITIES AT THE IZTACALA CAMPUS OF THE UNIVERSIDAD NACIONAL AUTONOMA DE MEXICO, MEXICO Mark S. Peterson and Nancy J. Brown-Peterson Special section co-editors Department of Coastal Sciences, The University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS 39564 USA In fall 2002, we had the opportunity to initiate a long-term collaboration with colleagues from the Iztacala campus of the Universidad Autonoma de Mexico (UNAM), whose research interests focus on coastal and nearshore fishes and deca- pod crustaceans of Veracruz state, Mexico. This is an undergraduate campus with a strong Biology department whose fac- ulty also maintain research programs despite limited sources of funding and a heavy teaching load. During the course of our initial visit, we realized that there is a wealth of unpublished undergraduate student research on understudied fish species. We developed a collaborative partnership in November 2002 between the faculty advisors from the Biology department at UNAM-Iztacala, the Department of Coastal Sciences, The University of Southern Mississippi and non-prof- it funding organizations interested in research in the Gulf of Mexico and Caribbean Sea. We selected exceptional senior and Masters theses from the Biology department at UNAM-Iztacala which were processed and submitted for peer-review in Gulf and Caribbean Research (see Peterson and Brown-Peterson 2004). The following publications are a continuation of the partnership. Acknowledgments Partial funding for this program stems from two Academic Exchanges between the Universidad Nacional Autonoma de Mexico - Iztacala and The University of Southern Mississippi (USM) to MSP and NBP. Extramural funding for trans- lation and publication came from Environmental Defense, the Harte Research Institute, and the USM College of Science and Technology. Maria Quimis-Ponce conducted the initial translations of the majority of the theses for this special sec- tion of Gulf and Caribbean Research. We particularly thank Dr. D.J. Grimes (USM) and J. Eranco-Eopez (UNAM- Iztacala) for providing funds for the Academic Exchange in 2002 and Dr. S. Chavez-Eopez and J. Eranco-Eopez (UNAM- Iztacala) for funds in 2003. We thank S.D. Hard, Managing Editor, for her assistance with this special section, and her exceptional technical ability. Literature Cited Peterson, M.S. and N.J. Brown-Peterson. (2004). Introduction to special section on research activities at the Iztacala campus of the Universidad Nacional Autonoma de Mexico, Mexico. Gulf and Caribbean Research 16:77-78. 121