Ge Florida clentist Volume 66 Spring, 2003 Number 2 ISSN: 0098-4590 CONTENTS Spatial and Temporal Influences of Environmental Conditions on Benthic Macroinvertebrates in Northeast Lake Jesup, Central Florida .......... Arshad Ali, Richard J. Lobinske, . Jan Frouz, and Robert J. Leckel, Jr. 69 Nutrient Composition of Some Insects and Arachnids ........................ Fred Punzo 84 Herbivory and Postgrazing Response in Hypericum cumulicola ........ Lars Brudvig and Pedro F. Quintana-Ascencio 99 Effect of Shear Forces on The Release of Brevetoxins From Karenia SPIT te a ee ek a ce tvabdenkcilsisiwbaserdasaceesateeenesss Dean F. Martin, Robert P. Carnahan, and Joseph J. Krzanowski 109 Temporal Diversity and Abundance of Drift Macrophytes and Associated Organisms in Mosquito Lagoon, Volusia County, Florida .............. Marie-Josée Abgrall and Linda J. Walters 113 Wildlife Mortality on U.S. Highway 441 Across Paynes Prairie, Alachua MPM SRGMEIO Me eR te) UA 8 cosas hisivcndeacisenecadednaecat ows Lora L. Smith and C. Kenneth Dodd, Jr. 128 Distribution of the Introduced Black Spiny-tailed Iguana (Ctenosaura saasles) On Tac Southwestern Coast of Florida .................00ce:..s0c06 Kenneth L. Krysko, F. Wayne King, Kevin M. Enge, and Anthony T. Reppas 141 Seed Dispersal by Gopherus polyphemus at Archbold Biological Station, a ee NNR AISI) coils dest etencbadnah yadedenciadaneaacdtens Jane E. Carlson, Eric S. Menges, and Peter L. Marks 147 ME re aE ah aulaade sd nuaee dnctes' sie Lawrence J. Hribar 155 EKATHSONAy ( MAY 1.9 2003 | _LiBRARIES FLORIDA SCIENTIST QUARTERLY JOURNAL OF THE FLORIDA ACADEMY OF SCIENCES Copyright © by the Florida Academy of Sciences, Inc. 2003 Editor: Dr. Dean F. Martin Co-Editor: Mrs. Barbara B. 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Martin, Co-Editor Volume 66 Spring, 2003 Number 2 Biological Sciences SPATIAL AND TEMPORAL INFLUENCES OF ENVIRONMENTAL CONDITIONS ON BENTHIC MACROINVERTEBRATES IN NORTHEAST LAKE JESUP, CENTRAL FLORIDA (1) (1,2) * , RICHARD J. LosinskE\? , JAN FROUZ AND ROBERT J. LECKEL, Jr. ARSHAD ALI ‘University of Florida, IFAS, Mid-Florida Research and Education Center 2725 Binion Road, Apopka, FL 32703-8504 Institute of Soil Biology, ASCR, Na sadkach 7, Ceské Budeéjovice, CZ-37005, Czech Republic ABSTRACT: The benthic macroinvertebrate community composition and selected water and sediments physico-chemical parameters at 15 permanent sampling stations in northeast Lake Jesup, central Florida, were studied monthly from December 1996 to December 1997. Crustacea (primarily Ostracoda) were numerically dominant (mean 3,645/m ), followed by Oligochaeta (898/m’ ), Gastropoda (mostly Tryonia aequicostata 898/m’), Chironomidae larvae (predominantly Glyptotendipes paripes 383/m ), Chaoboridae larvae (112/m?) and Hirudinea (107/m). Ordination analysis (CCA and variation partitioning) showed that month of sampling and sampling station together explained 64% of benthic community variability; sampling station explained 45% and sampling month 19% of variation. Significant density differences of various taxa were noted between sampling stations, but not between months of sampling. Clustering of benthic community by using TWINSPAN revealed differences between sand and soft organic sediments. CCA indicated sediment type as the most important environmental factor. The highest biomass and species number were recorded on sand substrate, with Isopoda, Nematoda, Polypedilum spp. larvae and Glyptotendipes paripes larvae as the typical inhabitants of sand sediment, whereas Tanypodinae larvae, Chaoboridae larvae and Tryonia aequicostata were typical for soft muck sediment. Key Words: Benthic invertebrates, community, Canonical Correspondence Analysis, Detrended Correspondence Analysis, sediments, physico-chemical conditions * Corresponding author: e-mail: rjlobinske@mail.ifas.ufl.edu 69 70 FLORIDA SCIENTIST [VOL. 66 THE sublittoral and littoral zones of lakes are an important transitional divide between terrestrial and aquatic environments in that they are subject to high variability of environmental influences and often support a diverse benthic community (Hakanson and Jansson, 1983). Qualitative and quantitative composi- tions of benthic organisms are sensitive and complex indicators of nutrient status of the lakes (Brundin, 1949; Prat, 1978; Winnel and White, 1986). However, use of benthos data as bioindicators of eutrophication is often complicated due to high spatial variability because of patchy distributions of benthic community as well as variations due to seasonality (Verneaux and Aleya, 1998; Reid et al., 1995; Kilgour et al., 2000). Some man-made and natural lakes in central Florida produce phenomenal numbers of adult chironomid midges that can cause severe nuisance problems and substantial economical losses (Ali, 1995). Larvae of some nuisance midge species may often occur in the littoral part of the lakes (Rasmussen, 1984). Therefore, a better understanding of environmental factors affecting the spatio-temporal distribution patterns of benthic communities in shallow lakes or in littoral parts of deep lakes is needed. The aim of this study was to investigate spatio-temporal changes of benthic community in a shallow littoral area of a natural lake in central Florida and to relate this pattern to simultaneous spatial and temporal changes of selected environmental variables. METHODs—Study area—The study was conducted in 350 ha northeast portion of eutrophic Lake Jesup (28°44'N, 81°14’W), Seminole County, Florida, north of Davis Point (28°45’N) to the confluence with the St. Johns River. Water depth in the study area was ca. 1 m but fluctuated due to local precipitation; water flow in either direction depended upon relative water elevation between the lake and the St. Johns River. For sampling purposes, fifteen evenly spaced stations were permanently established in the study area and a portable Global Positioning System (GPS) receiver was employed to navigate to each station in a double-hulled pontoon boat. Water, sediment and benthic samples were collected between 0800 and 1200 h on one day during the first week of each month from December 1996 to December 1997. Sampling—Selected water physico-chemical parameters were quantified monthly at each station. Water depth was measured with a graduated pole fitted with a disk at the base to prevent sediment penetration. Secchi disk transparency was assessed with a 20 cm diameter Secchi disk. Dissolved oxygen (Model 54A meter, Yellow Springs Instruments Company, Yellow Springs, OH), specific conductance and water temperature (Model 140 Conductivity-Temperature-Salinity meter, Orion Research Company, Boston, MA) were measured at the middle of water column, and at air-water and sediment-water in- terfaces. Water samples were collected from the middle of the water column at each station with a 2.2 L horizontal Alpha Bottle (Wildlife Supply Company, Saginaw, MI) to determine pH, turbidity and chlorophyll (a, 6 and total). These samples were transported on ice to the laboratory, and then stored at 4°C in the dark until analyzed within 24 hours. For sediment parameters, depth of soft sediments was measured with a graduated pole at each station monthly, while seasonal (December 1996, January, April, July and October 1997) quantitative sediment samples were collected using a sediment corer (Ali, 1984; Ali et al., 1988; Ali and Alam, 1996). Three surficial sediment samples (5 cm deep from sediment-water interface) were collected at stations 3, 6, 9, 12 and 15 and composited. Each composite sample was placed in a labeled polyethylene bag, transported to the laboratory on ice, and subsequently maintained at —10°C until processed and analyzed. To sample benthic organisms, one 15 X 15 cm Ekman dredge sample was collected monthly at each station during the study period. Where necessary, a pole-mounted Ekman dredge was used to insure sufficient substrate penetration. Sediment physical composition (muck, sand, or detritus) was visually No. 2 2003] ALI ET AL—MACROINVERTEBRATES IN LAKE JESUP va determined and recorded. Ekman dredge samples were transferred to 5 gallon plastic buckets for transport to the laboratory. Samples that could not be immediately processed on return to the laboratory were stored at 4°C and processed within 48 h of collection. Laboratory methods—The pH of water samples was measured in the laboratory at room temperature using an Orion Research Company Model 710A pH/ISE meter, and turbidity with a HF Instruments Company (Bolton, Ontario, Canada) Model DRT 1000 turbidity meter. For chlorophyll determination, 1000 ml of each water sample was vacuum filtered through 0.45 um, 47 mm diameter nylon filters (No. 7404-004, Whatman International Ltd., Maidstone, UK) using Buchner funnels. All chlorophyll analyses were done under green light to avoid chlorophyll photo-degradation (Inskeep and Bloom, 1985; Moran and Porath, 1980). Filters were placed in storage dishes, wrapped in aluminum foil to exclude light and stored at — 10°C until analyzed within 4 weeks. Chlorophyll a, b, and total chlorophyll were determined using N,N-dimethylformamide (DMF) extraction and spectrophoto- metric analysis (Inskeep and Bloom, 1985; Moran and Porath, 1980). Filtered water obtained from the chlorophyll analysis was used for the remaining water analyses. Fifty ml of the filtrate was used for Soluble Reactive Phosphorus (SRP) determination using the ascorbic acid method (APHA, 1992). Twenty five ml of the filtrate was acidified with 3 drops 12N HCl and stored in scintillation vials at — 10°C until transported to the University of Florida’s Analytical Research Laboratory (ARL) in Gainesville, FL, for determination of Total Kjeldahl Nitrogen (TKN) and Total Phosphorus (TP). Frozen sediment samples were thawed at room temperature, overlying water carefully decanted off and each was thoroughly mixed in a beaker. Sediment pH was determined with an Orion 710A pH/ISE meter. Fifteen grams of wet sediment from each sample were transferred to extraction flasks with 45 ml of distilled, deionized water and shaken for one hour. The contents of each extraction flask were vacuum filtered through a 0.2um filter and 25 ml of the filtrate used for SRP determination using the ascorbic acid method (APHA, 1992). One gram of wet sediment was placed in a tared beaker and dried at 100°C for 24 h to determine percent dry weight. The remaining wet sediments were dried at room temperature in disposable plastic trays, ground to pass through a 350 um mesh sieve and analyzed for Total Organic Carbon (TOC) using the method of Nelson and Sommers (1982). Samples of remaining dried sediments were sent to ARL, Gainesville, FL, for determination of TKN and TP. Benthic macroinvertebrate samples collected with Ekman dredge were washed through a 350 um mesh sieve in the laboratory. Each washed sample was transferred to a gridded, 30 X 40 cm white pan and examined under 2-4 of a dissecting microscope (Ali et al., 1976). Invertebrates were separated, identified and counted. The following taxonomic keys were used: Annelida to class—Pennak (1989); non- insect Arthropoda to class—Edmondson (1959) and Pennak (1989); Insecta to family—Merritt and Cummins (1996); Chironomidae to lowest practical level—Epler (1995); Mollusca to species—Thompson (1984), Heard (1979) and Pennak (1989); and other invertebrates to phylum—Edmondson (1959). For dry biomass determination, benthic invertebrates were divided into two groups: one group contained only Chironomidae and the other all other invertebrates including Mollusca with their shells in place. Each group was placed in a tared weighing dish and dried at 60°C for 24 h (Dermott and Paterson, 1974). Data analysis—Temporal and spatial analysis of collected data was done by using the computer software Instat version 2.05a. Where necessary, log(n+1) transformations of data were used to improve homoscedasticity. During analysis of data, stations were sorted by descending muck depth and station numbers reassigned from greatest depth (station 1) to least (station 15). These reassigned station numbers were used in all analyses. TWINSPAN (Hill, 1979) was used for clustering of community data and Canoco for Windows 4.0 was used for Detrended Correspondence Analysis (DCA), Canonical Correspondence Analysis (CCA), (ter Braak and Verdonschot, 1995; ter Braak and Smilauer, 1998) and variation partitioning (Borcard et al., 1992). Indirect ordination DCA was used to indicate approximate influence of all investigated environmental parameters, including those measured on seasonal basis (missing data were replaced by most probable values as recommended by ter Braak (1988), these values were obtained by extrapolation from known seasonally measured values). For CCA and variation partitioning, the variables with missing data points (measured on seasonal basis) were excluded. TA FLORIDA SCIENTIST [VOL. 66 TABLE 1. Overall mean (+SD) and maximum and minimum values of selected water and sediment physico-chemical parameters sampled at 15 permanent stations in Lake Jesup, central Florida, December 1996—December 1997. Parameter Mean + SD Maximum Water Depth (m) O9F=203 1.6 0.2 Secchi Disk Transparency (cm) AAs iil 100 25 Temperature (Oe 23.4) 2 Be8 29.4 16.3 Dissolved O> (ppm)! AO Suled 10.9 1.9 Conductance (uS/em)! 1,035 + 338 1,885 565 pH 8.67 + 0.50 9.92 7.00 Turbidity (NTU) 13.2) 22,5%6 32.0 2.6 SRP (ug/l) ay) ee ay 32.0 <0.1 Total P (mg/l) 0.02 + 0.06 0.40 <0.01 TKN (mg/l) ANI ae 748) 12:8 1.0 Chlorophyll a (mg/m?) 74.5 + 33.8 173.6 8.4 Chlorophyll 6 (mg/m?) 1326722 ses 133.8 <0.1 Total Chlorophyll (mg/m) 88.4 + 40.6 288.6 16.5 Sediment Muck depth (cm) 1224 120 0.05) different by repeated measures ANOVA and Tukey-Kramer multiple comparisons post test. Mean depth of muck sediments in the study area was 51 cm, ranging between <1 and 120 cm (Table 1). The lowest value existed at the sand bottom station 15 closest to the St. Johns River. Sediments were slightly acidic, with overall mean pH value of 6.64, ranging between 6.36 and 7.00. Nutrient concentrations in the sediments were high, with mean SRP 6.2 mg/kg, TP 0.8 mg/g, and TKN 12.8 mg/g. These nutrients were at the lowest concentrations at station 15. Mean total organic carbon content value was 9.6% with a range of 0.1% (station 15) to 17.0% (station 1). Sediments in the study area had a high water content, with overall mean of 23.0% dry mass, and ranging from 10% (station 9) to 75% in predominantly sand bottomed station 15 (Table 1). The largest number of invertebrate taxa (overall mean 8.3 taxa/station and cumulative of 17 total taxa collected) and highest macroinvertebrate biomass (overall mean 519.1 g/m”) were recorded at station 15 with sand bottom (Table 2). Among the invertebrate fauna, Crustacea predominated by Ostracoda (3,645/m°) were numerically the most abundant, followed by Oligochaeta (898/m7), the gas- tropod Tryonia aequicostata (584/m*~), Chironomidae larvae (predominantly G/ypto- tendipes paripes, 382/m*), Chaoboridae larvae (112/m*) and Hirudinea (107/m7) (Table 3). Ostracods had the highest frequency of occurrence (93.8% of benthic samples), followed by Oligochaeta (91.0%), larvae of the chironomid subfamily Tanypodinae (75.9%), Chaoboridae larvae (54.8%), Hirudinea (42.5%), and the mollusks Viviparous georgianus (37.9%), and T. aquicostata (30.3%). Other taxa shown in Table 3 occurred in ca. 20% of samples or less. The gastropod V. georgianus, though relatively few in numbers, apparently made the largest con- tribution to total invertebrate biomass due to their large size ranging up to 2 cm in 74 FLORIDA SCIENTIST [VOL. 66 TABLE 3. Overall mean (+SD) density, maximum density (No./ m°), and occurrence frequency (%) of benthic fauna at 15 sampling stations in northeast Lake Jesup, central Florida, December 1996— December 1997. Mean Maximum Occurence Taxa density density frequency (%) Nematoda 65 + 318 3,655 14.3 Annelida Oligochaeta 898 + 3442 39,345 91.0 Hirudinea 107 + 510 6,751 42.5 Mollusca Viviparous georgianus y= NW 1,161 3) 32) Tryonia aequicostata 584 + 2055 12,900 30.3 Physella heterostropha 02 234 43 0.5 Elliptio buckleyi 02 E=Bal 43 0.5 Crustacea Amphipoda HO = 492 122 19.4 Copepoda 72s 3} 473 16.9 Decapoda (eae 8) 215 8.7 Isopoda 8) ae 1S) 172 4.6 Ostracoda 3,645 + 20,119 271,760 93.8 Insecta Hemiptera jig |W) 129 4.1 Chironomus crassicaudatus joan 3) 645 oD Glyptotendipes paripes B82 2292 259 18,361 ed) Polypedilum spp. 0.7 + 6.8 86 1.0 Tanytarsin1 Ikea ©) 172 4.1 Tanypodinae 88 + 115 903 Ta other Chironomidae 0.7 = 70 86 1.5 Chaoboridae 1125 176 15032 54.8 Hydracarina | ay 43 0.5 diameter, measurements made with shells in place. This contribution is reflected in total dry biomass station values being the lowest (stations 4 and 10) where V. georgianus densities were the lowest compared to the other stations (Tables 2, 4). The finding that highest diversity and biomass was associated with sand substrates is in agreement with other lake benthos studies conducted in Florida (Cowell and Vodopich, 1981; Schramm and Jirka, 1989) and elsewhere in South Africa (Cyrus and Martin, 1988). Repeated measures ANOVA with Tukey-Kramer post-tests indicated significant differences (P < 0.05) of distribution between stations for many invertebrate taxa, especially station 15 supported significantly more G. paripes, V. georgianus, Oligo- chaeta, Nematoda, Decapoda, Isopoda and total benthic dry biomass (Tables 2, 4). The majority of taxa collected displayed either significantly higher density in sand substrates and/or were correlated with some sediment properties characteristic for sand substrate, such as decreasing TOC or muck sediment depth or increased sediment dry weight (Table 5). For some of these taxa, such as G. paripes, such habitat preferences have been documented (Provost, 1956; Cowell et al., 1975; McLachlan, 1976; Milleson, 1978; Rasmussen, 1984). Taxa that formed the bulk of the community on muck substrates usually did not display any significant preference for this substrate. The only exceptions were T. aequicostata and Hirudinea, which were significantly (P < 0.05) more abundant in muck sediments than sand. Stations 75 ALI ET AL.—\—MACROINVERTEBRATES IN LAKE JESUP No. 2 2003] ‘Jso} sod suostedwios gydnynur rourery-Aoyny, pure YAONY Somseour poywodar Aq yualaysIp (CO'O < d) Apueoyrusis Jou stam Joya] OURS oY} YJIM UUINJOO YoRe UI SURI] , Q@hIS + 6lLvhe & SS + 6 Qc@L + LE 9 CIC + ILP e 0+ 0 Be 90¢ + ISI Q LSTIT+O06LL 4 LL8 + 668 SI qe 7600S + CIVtT #8® O0F0 eB 0+0 qe cri + £9 eB 6 6Cl+ 9 ques 1962 Sol B Cle + 6IC Ee (Gl sae vl B 6887 = LI eB 0+0 eB OI+L qe 9CI + 6L eB cre = Lt Unc Saat e eB OVE + 88E US VE =2208 on eB . 9¢ = OL eB 070 ve 0-0 BES =esc Be S8t + 8SI RB 6th = 81 eB els + £6S (Ges {3 Gl B €8 + 9C BP 0+=0 ve 0+0 ® COl + 9V eS VeHL eB 6SS + OF Be St + 067 eB 0+0 TT eB 66l: + : 0.05) by ANOVA were detected. This was due to large values of variances occurring between aggregated distributions of the invertebrates sampled. Faunal differences between sand and soft organic sediments were also apparent at the community level. TWINSPAN clearly separated sand sediment station 15 from the other stations (Fig. 1), some muck sites were also ordinated into this cluster. No clear trend was noted between benthic invertebrate densities collected from muck sites. Some trend can be observed temporally; invertebrate samples from sites that contained Amphipoda as characteristic taxa contained summer invertebrate samples more often than other groups (Fig. 1). Figure 2 shows ordination diagrams of community data and environmental variables. Detrended Correspondence Analysis (Fig. 2a) interprets the pattern of all community data variability which is then correlated with environmental variables (indirect analysis). Selection of environmental variables does not affect species position in ordination diagram. In Figure 2a, all environmental variables, including those measured seasonally, were used. Two main gradients can be distinguished; the first (sediment condition gradient) follows the horizontal axis and represented a shift from sand to muck sediment (type of sediment, sediment dry mass, TOC and depth of soft sediment closely correlated with horizontal axis). The second (temporal gradient), was represented by water parameters which were highly variable during the year. To partition between temporal and spatial aspects of variability, two approaches were used. The first used CCA and variation partitioning (Fig 2b—d); the second No. 2 2003] ALI ET AL—MACROINVERTEBRATES IN LAKE JESUP Wi G. paripes larvae V. georgianus Chaoboridae larvae Nematoda Tanypodinae larvae Amphipoda 0 Hirundinea 1 Chaoboridae larvae Amphipoda Copepoda T. aequicostata Ilsopoda Amphipoda 00 01 10 1 |(N=111) |(N=54) |(N=12) |(N=13) 1-Dec 96, Jan-Jun, Sep-Dec 97 1-Jul, Aug 97 1-Oct 97 3-May, Jul, Oct 97 2-Dec 69, Jan-Jul, Sep-Dec 97 2-Aug 97 7-Jan 97 3-Jun 97 3-Nov, Dec 97 3-Dec 96-Apr 97, Jul-Sep 97 13-Jun 97 9-Sep 97 4-Dec 96, Jan-Apr, Jun-Sep, Nov, Dec 97 4-May, Oct 97 15-Dec96-Mar 97, Jul-Dec 97 11-Apr 97 5-Dec 96, Jan-Apr, Jul-Dec 97 5-May, Jun 97 13-Apr 97 6-Dec 96, Feb, Apr, Oct-Dec 97 6-Jan, May-Sep 97 14-Jan 97 7-Dec 96-Feb 97, Apr,Sep-Dec 97 7-May-Aug 97 15-Apr-Jul 97 8-Dec 96, Jan-Apr, Aug-Oct, Dec 97 8-May-Jul, Nov 97 9-Dec 96, Feb, Oct 97 9-Jan, Mar, Apr-Aug 97 10-Jan-Mar, May, Sep-Dec 97 10-Dec 96, Apr, Jul, Aug 97 11-Dec 96, Jan-Mar, May, Sep-Dec 97 11-Jun-Aug 97 12-Dec 96-May 9, Jul, Sep-Dec 97 12-Jun, Aug 97 13-Jul, Aug, Nov, Dec 97 13-Dec 96-Mar 97, Sep, Oct 97 14-May, Sep-Dec 97 14-Dec96, Feb, Apr, Jun-Aug 97 Fic. 1. Cladogram of benthic communities (TWINSPAN) recorded monthly from 15 sampling stations in northeast Lake Jesup, central Florida, December 1996 to December 1997; (0, 2, 5, 20, and 100 were used cut levels). The numbers in each column under each group (group 00—11) are sampling station numbers that are followed by month(s) of sampling. compared correlations between species and environmental variables based either on month or station means (Table 6). To partition overall spatial and temporal effects, the month and site of sampling were used as the only explanatory variables in CCA (ordination diagram not shown). Month and sample station combined explained 64% of benthic community variability, station variation explained 45% and monthly (temporal) variation 19%. This is in agreement with Verneaux and Aleya (1998) who reported influence of spatial and temporal factors on benthic community organization, with spatial environmental variability being prominent. In Figure 2b, only significant (P < 0.05) monthly measured variables determined by forward selection were included in CCA. The general pattern is similar to Figure 2a, where the most important horizontal gradient is represented by presence or absence of sand, with the water parameters representing a vertical, temporal gradient. When effect of time was removed (months used as covariables), the presence or absence of sand sediment became the most important environmental variable (Fig 2c). Considering the sediment condition gradient (Figs. 2b, c), Isopoda, Nematoda, Polypedilum \arvae and G. paripes larvae were characteristic for sand substrates, whereas Tanypodinae larvae and Chaoboridae larvae were typical for soft muck sediment. However, the latter two taxa did not display significant correlations with sediment conditions associated with muck sediments (Table 5). Thus, these taxa were probably tolerant of soft organic sediment (and associated conditions such as low dissolved oxygen in the sediments) rather than having a preference for these sediments. Predator avoidance could also be a factor influencing these organisms. 78 FLORIDA SCIENTIST [VOL. 66 : OP. heterostropha +1 ) E. buckleyi T. aequicostata Ostracoda Hirudinea Hemiptera 8 P. heterostropha _ Tanytarsini ‘. Conductivity ! Hydracarina T. aequicostata : Turbidity\ cc V. georgianus Mud Hydracarina Toc i a rs aig pee Decapoda Muck depth @ceas= eC: ee FEET oa CE ~e an i emda = ONE xT SX Soil dry weight| 127yPodinae Chaoboridae Copepoda Oligochaeta Water pH fa PCT if georgianus : Bd | Chlofophyll b~Tanytarsini ve Hemiptera Decapodal * 2 Nematoda C.crassicaudatus G paripes C. crassicaudatus Secchi Copepoda Chaoboridae QOligochaeta Tanypodinae Ostracoda fo) Dissolved O02 -1.0 +1.0 E. buckleyi a + d E. buckleyi empties . ‘ Dissolved O02 : c, obpediium Water SRPO opepoda Nematoda Polypendilum Isopoda : . P._ heterostropha O Amphipoda V : Tanytarsuu Water SRP “4, 1. aequicostatg avery, Tse fea Hurudinea fey accenna Oligocaheta \ Ostracoda — y Neanda SE Gee : Chaobondae Depth cme ah Fagen 5 rae Sn Soil dry weight Tanypodinae = Amphipoda aD : lsopoda—> 111 bis barre Soil SRP Hydracarina Himudinea ) P. heterostropha rbidity |, paripes T. aequicostata ‘Panytarsini Sand Ostracoda Secchi Decapoda G.paripes C. crassicaudatus Chaobonidae Copepoda Water pH ; Tanypodinae Dissolved O2 | Chlorophyll b C. crassicaudatus Temperature Decapoda ; Conductivity Oligochaeta Depth =1'0 +1.0 Fic. 2. Ordination diagrams of benthic communities and environmental variables recorded monthly from 15 permanent sampling stations in northeast Lake Jesup, central Florida, December 1996— December 1997. a—DCA, b—CCA of significant (P < 0.05) variables selected by forward selection, c—pCCA of spatial variability (months of sampling used as a covariables), significant (P < 0.05) variables selected by forward selection, d—pCCA of temporal variability (sampling station used as covariables) significant (P < 0.05) variables selected by forward selection. For all presented CCA and pCCA analyses, the first ordination axes were significant (P < 0.005). Footnote: 1—Water SRP, 2— Chlorophyll a, 3—Total chlorophyll, 4—Water N, 5—Water P, 6—Chlorophyll 5, 7—Temperature. No. 2 2003] ALI ET AL.—MACROINVERTEBRATES IN LAKE JESUP 719 When the effect of sampling station was removed, water temperature and depth were the most important environmental variables (Fig. 2d). The high importance of temperature for seasonal variation in invertebrate community is in agreement with findings of Thorp and Chesser (1983). The effect of depth is likely to be indirect given by correlation of seasonal changes of water level in the lake with most of other water parameters. Important also were temporal changes in water depth and phyto- plankton abundance (measured by chlorophyll 5 and total chlorophyll concentra- tion). These parameters may also affect some water properties such as Secchi disk transparency, turbidity and pH (Fig 2d). Ordination analysis indicated that the sediment parameters had more influence on spatial variability whereas water parameters were associated with temporal variability; however, many water parameters showed spatial correlations (Fig 2c, Tables 6, 7). The spatial and temporal effect of individual water variables on individual taxa was often not consistent (Tables 6, 7). In only three cases did temporal and spatial correlations significantly follow the same trend, such as the positive correlation between Chaoboridae larvae and dissolved oxygen concentra- tion. This may imply that Chaoboridae larvae reflect oxygen concentration directly and that they are sufficient migrants to follow this gradient. Most often, the response of a taxon to a factor was significant only spatially or temporally (Tables 6, 7). For example, Chaoboridae larval density was significantly correlated (negative correlation) with monthly mean water temperature, but not with spatial variation of temperature. This preference for cooler conditions may be a temporal adaptation by the insect to exploit resources with less interspecific competition or to avoid predators. The lack of spatial correlation of chaoborid larvae with water temperature is not surprising because spatial variability of temperature was negligible at any given time but was substantial temporally. In some cases, opposing spatial and temporal responses to a given factor (sign of correlation coefficients differed) were noted, such as between Amphipoda and specific conductance. There could be several reasons for inconsistent spatial and temporal responses or taxa to individual factors. One may be the difference in temporal and spatial variability as described above for temperature. Another, that correlation was affected by co-linearity with other factors. For some correlations, especially those with low correlation co- efficients, the significance may be a chance occurrence or a statistical artifact. An additional aspect that can complicate evaluation of spatio-temporal patterns is that spatial distribution is strongly affected by previous history. Many benthic organisms are slow migrants or sessile during most of their life cycle and spatial distribution may be affected by not only actual conditions but also conditions when a generation was established. Finally, organisms may be influenced by environ- mental parameters in different ways during their life cycle. The present study also provides baseline data to elucidate changes and possible effects on benthic invertebrate communities and water and sediment conditions in northeastern Lake Jesup resulting from a proposed restoration of historic water flow between the St. Johns River and the lake (Ali et al., 1998). The proposed restoration could result in greater water flows within the northeastern section of the lake, causing scouring of soft, organic sediments and leaving sand substrates in a greater [VOL. 66 FLORIDA SCIENTIST 80 Sl Oe 109°0— 69¢°0— 6£9°0 Ie8'0—- SEM seproqoeryy) Svs 0 SEAT] seutpoddur |, 9€5'0— L6S°0 89S 0- ovArey “dds wuinjipaddjog S060 BpooensO S650 6790 6cL'0 epodos] ISsO— epodadog 89L°0 epodiydury 8eS 0 pivjsoanbav DIUOAA J, 869 0— 909°0 999'0 Snuv1s810a8 SNOADAIALA 6€5°0 vouIpnityy oc9'0 8£9 0 ByovYysOsIIO £09°0 TES O 6£9'0— PpOJPWION| udsOININ snioydsoyg q D snioydsoyg Hd asourjonpuod uashxQ aimeloduiay Aouaredsuery yidog UOXP |, Tyeproly [B10 yAydoroyyg «= fAydoioyyQ = OATOWOYSCCSTNE AA oytoads PoAlOssiq Toe Ysiq 1wys99e¢ Jaye [e101 s1qn[0$ “soreyt ore UOTOeMp otsoddo ut ‘poutjiopun aie JUSIOYJeod UOTIeTaLIOO [eneds se UONIEIIP ours UI SJUSTOYJOOS UOTL[OLOD “1 66] JOquiadeq] 0} O66 JaquId.aq ‘epLOy{ [e.NUI. ‘dnsar aye] JseoyLOU UT suUOTEIS C] Iv poyduwes sayeIQoLIOAUIOIOVU OTYJUNq pue sIojoUreIed Jeoruayo-oorskyd Joyem pojoopas useMjoq (4) SoNTeA JUIIOYJIOD uUOTIeaLIOD (¢] = UW) (sued ATYUOUT) [e1oduIa) ([Q'O > qd) WeoyIUsIs Jo xR, °9 ATAV], 8] ALI ET AL.—MACROINVERTEBRATES IN LAKE JESUP No. 2 2003] €89°0 76S'0 OvAIR] BepLIOgory,) €79'0 ovale] ovurpoddur [, Kei O= 9EL0-— =LO9'0- 6850 €£8'0 oes] “dds winpipadAjog 189 0— NOS V=— C75 Ve 069°0 eae] Sadiipd sadipuajojddjH 16S'0— Tes0 L8S'0 VAIL] SNIDPNDIISSDAI SNULOUOALY D EGLO cOL 0— SOS 0 c69°0 — eroydruaH] y6s 0— LCES'0 079 0— CCS 0 BposeDsO ols: 0- 909'0 epodos] 19¢°0 epodeseq 989° 0— epodrydury 619: 0— 019'0— pjvjsoombav DIUOALT, Peso SNUDIBAOIS snoAvdlalA SOKO = vourpmainy vrs 0— LIS 0 t190 eyaeYyoos|O LOS'0— 9ES 0— 97090 BpoyeUloN] snioydsoyg D snioydsoyg AlIpiqiny, Hd gourjonpuog, ~=uashkxQ aimerodwoy Aouciedsuviy, yideqd UOXR |, [R10L yAydoroyyD DATIOVOY JOA oytoeds PoaTossiq Joye ysiq 1yose¢ INCA aqqnjos “Sore die UOTOaIIp oysoddo ut ‘pouTjopuN are JUSIOYJIOS UONLIALOS [etodtua} se UONIaIp DUIRS UI SJUSIIYJOO UONPIAOD */66] JOQuID00q 01 OGG] JOquID00q ‘eplIop jemuso ‘dnsop aye] IsvoyOU UT SUOTEIS CT IV poTdues sayeAqoWOAUTOJOVU STYUEG PUL ssojouesed jeoruayo-oo1skyd JojeM poyoojas UEMIOg (/) SONA JUSIOYJOOO UONL]aLI09 (G] = Uv) (sURdU UONRIS) [eNeds ([Q' > qd) WUvOYTUSIS JO XLARA “L ITAVL, 82 FLORIDA SCIENTIST [VOL. 66 area of the lake bottom. With the greater abundance and diversity of benthic macroinvertebrates recorded at sand bottom station 15, this could result in greater overall abundance and diversity of macrobenthos in this section of Lake Jesup. ACKNOWLEDGMENTS—This study was supported by a grant from the St. Johns River Water Management District (contract 96G345) and partly by research plan of ASCR, Institute of Soil Biology (Z 6 066 911), Czech Republic. The authors express gratitude to Julie L. Bortles for technical assistance. This is Florida Agricultural Experiment Station Journal Series R-08840. LITERATURE CITED Aut, A. 1984. A simple and efficient sediment corer for shallow lakes. J. Environ. Qual. 13:63—66. . 1995. Nuisance, economic impact and possibilities for control. Pp. 339-364. In: ARMITAGE, P. D., P. S. CRANSTON, AND L. C. V. PINDER (eds.), The Chironomidae: The Biology and Ecology of Non- biting Midges. Chapman and Hall, London. AND M. ALaM. 1996. Nutrient levels at the sediment-water interface in Lake Jesup, Florida. Florida Scient. 59:20—29. , R. J. LOBINSKE, AND J. L. BorTLEs. 1998. Determination of Sediment and Water Column Nutrient Concentrations and Benthic Invertebrate Community Composition and Abundance in Northeast Lake Jesup, Central Florida. Final report to St. Johns River Water Management District. Contract #96G345. 86 pp. , M. S. MuLLa, B. A. FEDERICI, AND F. W. PELSUE. 1976. Seasonal changes of chironomid fauna and rainfall reducing chironomids in urban flood control channels. Environ. Entomol. 6:619-622. , K. R. ReDpDy, AND W. F. Desusk. 1988. Seasonal changes in sediment water chemistry of a subtropical shallow eutrophic lake. Hydrobiologia 159:156—167. APHA. 1992. Standard Methods for the Examination of Water and Wastewater. 18th Edition. Am. Public Health Assoc. Washington, D.C. 1018 pp. Borcarb, D., P. LEGENDRE, AND P. DRAPEAU. 1992. Partialling out the spatial component of ecological variation. Ecology 73:1045—1055. BRUNDIN, L. 1949. Chironomiden und andere bodentiere der Sudswedishe Urgebirgseen. Rep. Inst. Freshwat. Res, Drotingholm 30:1—914. CoweELL, B. C., C. W. Dye, AND R. C. Apdams. 1975. A synoptic study of the limnology of Lake Thonotosassa, Florida. Part 1. Effects of primary treated sewage and citrus wastes. Hydrobiologia 46:301-345. AND D. S. Vopopicu. 1981. Distribution and seasonal abundance of benthic macroinvertebrates in a subtropical Florida lake. Hydrobiologia 78:97—105. Cyrus, D. P. AND T. J. MarTIN. 1988. Distribution and abundance of the benthos in the sediments of Lake Cubhu: A freshwater coastal lake in Zululand, South Africa. J. Limnol. Soc. Southern Africa 14:93-101. Dermott, R. M. anp C. G. PATERSON. 1974. Determining dry weight and percentage dry matter of chironomid larvae. Can. J. Zool. 92:1243-1250. Epmonpson, W. T. 1959. Freshwater Biology. 2nd Edition. John Wiley and Sons. New York, NY. 1248 pp. Eper, J. H. 1995. Identification Manual for the Larval Chironomidae (Diptera) of Florida. (Rev. Ed.). Fla. Dept. of Environ. Protection, Tallahassee, FL. 317 pp. HAKANSON, L. AND M. JANSSON. 1983. Principles of Lake Sedimentology. Springer-Verlag, New York. Hearb, W. H. 1979. Identification Manual for the Freshwater Clams of Florida. Fla. Dept. of Environ. Regulation, Tallahassee, FL. 82 pp. Hut, O. M. 1979. Twinspan—A FORTRAN program for arranging multivariant data in a two way table by classification of the individuals and attributes. Cornell Univ., Ithaca, NY. Kitcour, B. W., R. C. BAILEY, AND E. T. HoweLv. 2000. Factors influencing changes in the nearshore benthic community on the Canadian side of Lake Ontario. J. Great Lakes Res. 26:272—286. No. 2 2003] ALI ET AL—MACROINVERTEBRATES IN LAKE JESUP 83 INSKEEP, W. P. AND P. R. BLoom. 1985. Extinction coefficients of chlorophyll a and b in N,N- dimethylformamide and 80% acetone. Plant Physiol. 77:483—-485. McLacuian, A. J. 1976. Factors restricting the range of Glyptotendipes paripes Edwards (Diptera: Chironomidae) in bog lake. J. Anim. Ecol. 45:105—113. Merritt, R. W. AND K. W. Cummins. 1996. An Introduction to the Aquatic Insects of North America. 3rd Edition. Kendal/Hunt Publishing Company, Dubuque, IA. 862 pp. MiLeson, J. F. 1978. Limnological Investigations of Seven Lakes of the Istokpoga Drainage Basin. Technical Publication 78-1. South Florida Water Management District, West Palm Beach, FL. 170 pp. Moran, R. AND D. PoratH. 1980. Chlorophyll determination in intact tissues using N,N- dimethylformamide. Plant Physiol. 65:478-479. NELSON, W. L. AND L. E. Sommers. 1982. Total carbon, organic carbon, and organic matter. Pp. 539-579. In: Pace, A. L. (ed.), Methods of Soil Analysis. Part 2. Chemical and Microbiological Properties. Am. Soc. Agron., Madison, WI. PENNAK, R. W. 1989. Freshwater Invertebrates of the United States. Protozoa to Mollusca. 3rd Edition. John Wiley and Sons, New York, NY. 628 pp. Prat, N. 1978. Benthos typology of Spanish reservoir. Ver. Int. Ver. Limnol. 20:1647—1651. Provost, M. W. 1956. The Production of Chironomids in the Lakes of the Winter Haven Area. Preliminary Study. Florida State Board of Health, Tallahassee, FL. 36 pp. RASMUSSEN, J. B. 1984. The life history, distribution, and production of Chironomus riparius and Glyptotendipes paripes in prairie pond. Hydrobiologia 119:65—72. Rep, R. A., K. M. Somers, AND S. M. Davin. 1995. Spatial and temporal variation in littoral-zone benthic invertebrates from three south-central Ontario lakes. Can. J. Fish. Aquat. Sci. 52:1406—1420. ScHRAMM, H. L. Jr., AND K. J. JIRKA. 1989. Effects of aquatic macrophytes on benthic macroinvertebrates in two Florida (USA) lakes. J. Freshwat. Ecol. 5:1—12. TER BRAAK, C. J. F. 1988. Canoco—a Fortran program for canonical community ordination by corres- pondence analysis, principal component analysis and redundancy analysis (version 2.1). GLW Technical report LWA-88-02, Wageningen, The Netherlands. 55 pp. AND P. Smilauer. 1998. Canoco Reference Manual and Users Guide to Canoco for Windows: Software for Canonical Community Ordination (Version 4). Microcomputer Power, Ithaca, NY. 352 pp. AND P. F. M. VERDONSCHOT. 1995. Canonical correspondence analysis and related multivariate methods in aquatic ecology. Aquat. Sci. 57:255—289. THOompsSON, F. G. 1984. The Freshwater Snails of Florida. A Manual for Identification. Univ. of Fla. Press, Gainesville, FL. 94 pp. THorpP, J. H. AND R. K. CHESsER. 1983. Seasonal response of lentic midge assemblages to environmental gradients. Holarctic Ecol. 6:123—132. VERNEAUX, V. AND L. ALEYA. 1998. Spatial and temporal distribution of chironomid larvae (Diptera: Nematocera) at the sediment-water interface in Lake Abbaye (Jura, France). Hydrobiologia 373/ 374:169-180. WINNEL, M. H. AND D. S. Wuite. 1985. Trophic status of southeastern Lake Michigan (USA) based on the Chironomidae (Diptera). J. Great Lakes Res. 11:540-548. Florida Scient. 66(2): 69-83. 2003 Accepted: August 27, 2002 Biological Sciences NUTRIENT COMPOSITION OF SOME INSECTS AND ARACHNIDS FRED PUNZO* Department of Biology, Box 5F, University of Tampa, Tampa, FL 33606 ABSTRACT: Although many aspects concerning the nutrient requirements of insectivores are poorly understood, it is important to ascertain the nutrient composition of a wide range of invertebrate prey species so that more informed decisions can be made with respect to the feeding regimes used to maintain insectivores in captivity. In addition, this information is essential for a more comprehensive understanding of the diet composition and optimal foraging decisions of insectivores under natural conditions. In this study I report on the nutrient composition (water content, ash, crude fat, total nitrogen, minerals and trace elements, and fat-soluble vitamins) of 16 species of arachnids comprising 4 orders and 20 species of insects comprising 9 orders. Water content ranged from 58-71%. Crude fat content (as % dry matter, DM) ranged from 11-72%, with typically higher values observed for larval stages of insects as compared to adults. Total nitrogen, neutral detergent fiber, and ash ranged from 3—10% DM, 10-19%, and 2-9%, respectively. The insects and arachnids sampled in this study met the dietary requirements of insectivores with respect to minerals and trace elements including Mg, P, Ca, Cu, Fe, Mn and Zn. Concentrations of vitamins E and A were quite variable among the taxa. In spiders, vitamin E content ranged from 43.2—201.2 IU/kg; vitamin A levels ranged from 144.5-426.3 IU/kg. Scorpions and whipscorpions had significantly lower levels of vitamin E. In insects, vitamin E levels ranged from 17.7— 512.5 IU/kg; vitamin A levels ranged from 11.4—803.2 IU/kg. The values recorded for these fat-soluble vitamins fell below the daily requirements that are known for some insectivores. Key Words: arachnids, insects, nutrient composition INsEcTS and spiders comprise a major portion of the diets of numerous insectivores, including those species maintained in zoos and research laboratories. The ability to keep animals healthy and to breed them under captive conditions depends on diets containing essential nutrient requirements. Although there is a large body of information available on various behavioral aspects of feeding in in- sectivores (Curio, 1976; Price, 1997; Punzo, 1998a, 2000a), little information is avail- able on the actual nutrient composition of arthropods (Scriber and Slansky, 1981; Simpson and Raubenheimer, 1995; Barker et al., 1998). Most of the research on the nutrient composition of arthropods has focused on the mineral content of commercially-raised insects (McFarlane, 1991; Studier and Sevick, 1992; Finke, 2002) with less attention given to other nutritional components such as fat-soluble vitamins, crude fat, and total nitrogen (Barker et al., 1998). In addition, few data are available on the nutrient composition of arachnids (Nentwig, 1987; Foelix, 1996). The purpose of this study is to provide more comprehensive data on the nutrient * E-mail: Fpunzo@ut.edu 84 No. 2 2003] PUNZO—NUTRIENT LEVELS—INSECTS AND ARACHNIDS 85 composition of naturally-occurring insects and arachnids from a variety of mesic and xeric habitats that can be used primarily by individuals involved in field studies on the energy budgets of insectivores in areas where these invertebrates occur. In addition, the data may also be useful for scientists involved in the mass rearing of arthropods, as well as in animal husbandry where the evaluation of the diets of insectivores maintained in laboratories or zoological parks is of paramount importance. MATERIALS AND METHODS—Species and locality information—Table | lists the species of insects and arachnids used in this study, their capture sites, and mean body masses and lengths. Some of the species analyzed (Drosophila melanogaster, Acheta domesticus, Tenebrio molitor) were obtained from laboratory stock cultures maintained in my laboratory for 5—6 years. The other species were collected from areas of the Sonoran (Cochise Co., Arizona) and Chihuahuan (Brewster, Presidio, and Terrell Counties) deserts in Texas, and from various locations in Florida during early summer months (June and July). These months were chosen because they represent periods where arachnids and insects, as well as their animal and plant foods, are in greatest abundance (Punzo, 2000a, 2000b, 2001). Insects and arachnids were collected from trees, shrubs, grasses, rock faces, and ground surfaces using sweep nets, pitfall traps, adhesive boards (type 2874 Stiky Strips, BioQuip, Gardena, CA), Burlese funnels (Model 3464, Carolina Biological Supply, Burlington, NC) ultraviolet (Model 2836) and New Jersey (Model 2856) light traps (BioQuip), and a portable insect vacuum pump (BioQuip, Model 2820A). Laboratory stock cultures of the adult fruitfly Drosophila melanogaster were reared on Instant Drosophila medium (Carolina Biological Supply). Yellow mealworms (Tenebrio molitor, 200-300 mm length) were reared on a diet of wheat bran, oatmeal, and apple and potato slices. House crickets (Acheta domesticus) were fed on a diet consisting of commercial dog chow (Ralston Purina, St. Louis, MO) in combination with oatmeal, spinach leaves, potato slices, and ground bone meal. Insects and arachnids collected in the field were placed on ice, frozen at —20°C within 8 hr of capture, and stored for subsequent nutrient analyses. The body length of all insects and spiders were measured using a Vernier caliper or a Unitron Model 44W dissecting microscope fitted with an ocular micrometer. All body masses were recorded to the nearest 0.1 g using a Sartorius Model 501 electronic analytical balance. Nutrient composition analyses—Duplicate samples were tested for all nutrient analyses. To determine the percentage composition of moisture and total ash content samples were thawed at room temperature and whole specimens were homogenized using a tissue homogenizer (Model RG-70-1936, Carolina Biological Supply, Burlington, NC). Samples (0.5 g) were weighed to the nearest 0.1 g, then dried, and the percent moisture determined as described by Ellis (1984). Samples were then incinerated in a muffle furnace for 14 hr for determination of total ash content. Crude fats were extracted and analyzed according to the AOAC method (1996). Tissue samples were dried and placed in ethy! alcohol to denature the proteins to prevent them from being washed out with the fats during the extraction period. This was followed by extraction with petroleum ether. Chitin was analyzed using neutral detergent fiber (NDF) as described by Stelmock and co-workers (1985). Vitamins A and E were determined using the fluorometric method described by Taylor and co- workers (1976). Tissue samples were homogenized in a solution consisting of 1.0 ml of 25% sodium ascorbate and 5.0 ml of 2 mM EDTA. Samples were then mixed with 5.0 ml of 95% ethanol and 1.0 ml of 50% KOH, and saponified by incubating in a water bath (70°C) for 20 min, then cooled using an ice bath. Fat-soluble vitamins were extracted with 1.0 ml of hexane. A 1.0 ml aliquot of the hexane layer was evaporated under nitrogen, and subsequent saponification, extraction and evaporation procedures were performed under yellow light. Samples were then reconstituted with 0.30 ml of ethanol. A Beckman Model 760C liquid chromatograph with a 10-cm reversed-phase column was used to measure tocopherols and retinol as indices of vitamins E and A, respectively. The mobile phase consisted of 90:10 methanol:water for retinol, and 95:5 methanol:water for tocopherols. The flow rate was 2.5 ml/min. Concentrations of tocopherols were determined with a Beckman fluorescence spectrophotometer (ex- 86 FLORIDA SCIENTIST [VOL. 66 TABLE |. Species of insects and arachnids used in nutrient composition analyses and the sites at which they were collected. Data on mass (g) and body length (mm) are also included; values expressed as means + S.D. (N = 20 specimens for each species/life cycle stage) Species Collection site Mass (g) Length (mm) ARACHNIDA* Araneae (spiders) Araneidae (orbweaving spiders) Argiope aurantia Hillsborough Co., FL 0.62 + 0.18 19:3 235i Micrathena sagittata Polk Co., FL 0.45 + 0.09 8. el Ctenidae Ctenus captiosus Hillsborough Co., FL 0.38 + 0.06 10.8 + 0.9 Deinopidae (ogrefaced spiders) Deinopis spinosa Hillsborough Co., FL 0.23 + 0.04 DIP ase) Filistatidae (crevice spiders) Kukulcania hibernalis Hillsborough Co., FL 0.54 + 0.11 10.6 + 1.7 Lycosidae (wolf spiders) Hogna carolinensis Pinellas Co., FL 3.01 + 0.81 18.7 + 2.8 Trochosa parthenus Hillsborough Co., FL 0.44 + 0.03 7.7 + 0.6 Oxyopidae (lynx spiders) Oxyopes salticus Hillsborough Co., FL 0.29 + 0:02 48 = 14 Theraphosidae (tarantulas) Aphonopelma hentzi Presidio Co., TX 7.63 + 1.05 Bell ae 257) Theridiidae (cobweb weavers) Latrodectans mactans Pinellas Co., FL 0.23 + 0.01 96+ 1.3 Theridion pictipes Hillsborough Co., FL 0.25 + 0.03 3.5) = 1058 Thomisidae (crab spiders) Misumenoides formosipes Presidio Co., TX 0.33 + 0.04 74 + 0.8 Scorpionida (scorpions) Buthidae Centruroides hentzi Highlands Co., FL 2.36722 OG 38.8 + 2.6 Vaejovidae Paruroctonus gracilior Brewster Co., TX 1.89 + 0.43 pee |e) Solifugae (wind scorpions) Ammotrechellidae Ammotrechella stimpsoni Highlands Co., FL Lily 083 7 =a Uropygi (whip scorpions) Thelyphonidae Mastigoproctus giganteus Cochise Co., AZ Dols (STL 41.1 + 2.9 Brewster Co., TX 5.37 + 0.41 44.3 + 1.8 INSECTA? Coleoptera (beetles) Carabidae (ground beetles) Calasoma scrutator (adults) Brewster Co., TX 0.34 + 0.06 92 =k Omophron obliteratum (larvae) Presidio Co., TX O.2 te sOn iu 2.9 + 0.4 (adults) Presidio Co., TX 0.31 + 0.02 8.8 + 0.7 Cerambycidae (longhorn beetles) Coenopaeus palmeri (adults) Presidio Co., TX 0.28 + 0.02 12 es Lycidae (net-winged beetles) Lycus ferandezi (adults) Brewster Co., TX 0.19 + 0.01 4s 10g Scarabaeidae (scarab beetles) Dynastes titylus (larvae) Highlands Co., FL 0.32 + 0.04 8.9 + 5 No. 2 2003] TABLE 1. Continued. Species Pelidnota punctata (larvae) (adults) Tenebrionidae (tenebrionids) Alobates pennsylvanica (adults) Tenebrio molitor (larvae) (adults) Dictyoptera Blatellidae (German cockroach) Blatella germanica (nymphs) Blattidae (American cockroach) Periplaneta americana (nymphs) (adults) Diptera (flies) Drosophilidae (fruit flies) Drosophila melanogaster (adults) Hemiptera Coreidae (leaf-footed bugs) Acanthocephala terminalis (adults) Homoptera Cicadidae (cicadas) Tibicen canicularis (adults) Isoptera Rhinotermitidae Reticultermes hesperus (workers) Lepidoptera Heliconiidae (zebra butterflies) Heliconius charitonius (adults) (larvae) Sphingidae (sphinx moths) Pandora pandorus (adults) (larvae) Neuroptera Chrysopidae (lacewings) Chrysopa carnia (adults) Orthoptera Acrididae (grasshoppers) Schistocerca obscura (nymphs) Gryllidae (crickets) Acheta domesticus (adults) Gryllus assimilis (adults) * All arachnids were adult females. > All adult insects were females. Collection site Hillsborough Co., FL Hillsborough Co., FL Hillsborough Co., FL Laboratory stock culture Lab. stock culture Hillsborough Co., FL Hillsborough Co., FL Hillsborough Co., FL Laboratory stock culture Hillsborough Co., FL Pinellas Co., FL Polk Cox FE Presidio Co., TX Hillsborough Co., FL Hillsborough Co., FL Hillsborough Co., FL Hillsborough Co., FL Hillsborough Co., FL Leon Co., FL Polk Coy FIL Terrell Co., TX Laboratory stock culture Pinellas Co., FL PUNZO—NUTRIENT LEVELS—INSECTS AND ARACHNIDS Mass (g) O27 220303 O28 25)0;05 0.27 + 0.04 0.12 + 0.01 O29 == 0102 0.17 + 0.02 0.24 + 0.03 0:87 = 051 <0.01 <0.01 0.26 + 0.05 1.56 + 0.24 0.06 + 0.01 Orose==s021 121 = "0:08 O72 = Ome 325250 0322 Os 22 OL 0.41 + 0.27 O22-=0:01 0.24 + 0.01 0.25 + 0.01 0.17 = 0.02 87 Length (mm) Lali 273 92 = 05 Oe ae Nall Sey 22 2 IES) 1038 4.8 + 0.6 TES. = OM DDS eet 646) 25) (00)! Bre = O20 YP2 2a 2 Sie as eie4) Ba =2n03 12.4 + 14 18.2 + 2.4 14.4 + 1.6 203025 3:5 10.3 + 0.8 14.7 + 2.8 Ze 2,.8) es IES ene!) Les 3) 88 FLORIDA SCIENTIST [VOL. 66 citation wavelength = 280 nm; emission wavelength > 310 nm). Retinol was determined at 325 nm. External standards were compared to sample extracts for final vitamin concentrations. Vitamin A activity was calculated as 0.3 wg retinol = 1 IU, and vitamin E activity as 1.0 mg a-tocopherol = 1.49 IU, 1.0 mg y-tocopherol = 0.15 IU, and 1.0 mg 6-tocopherol = 0.05 IU. Tissue samples were analyzed for mineral analyses according to the atomic absorption methods described by Perkin-Elmer (1982). Total nitrogen was analyzed using the macro-Kjeldahl method with a copper catalyst (Ellis, 1984). Acid detergent fiber nitrogen (ADF-N), which is an index of chemically- bound nitrogen, was determined using the acid detergent fiber method described by Frye and Calvert (1989). Tissue samples were boiled in an acid detergent solution for 1.5 hr, filtered using Whatman # 54 paper, and rinsed with water. The subsequent filtrate was analyzed by the Kjeldahl method (Ellis, 1984). Statistical procedures—Data were expressed as means + SD. Differences among means within each group were assessed using unpaired f-tests and analysis of variance (ANOVA) (Sokal and Rohlf, 1995). LSD values were calculated using the Tukey test with P < 0.05. RESULTS AND DiscussioN—The water content and nutrient composition (crude fat, total nitrogen, ADF-N, NDF, ash) of the insects and arachnids analyzed in this study are shown in Table 2. There were some significant differences among field- collected and laboratory-reared species for all nutrient categories except NDF. Among the arachnids, the spiders, A. aurantia, M. sagittata, K. hibernalis, H. carolinensis, A. hentzi, L. mactans, T. pictipes, and M. formosipes contained the highest percentage composition of water. No significant differences in water content were found for any of the scorpions, solifugids or whip scorpions analyzed. With respect to the insects, the termite R. hesperus, nymphs of the grasshopper S. obscura, and the crickets A. domesticus and G. assimilis exhibited the highest water content. Presumably, prey with a higher water content would provide more moisture for insectivores, and this would be most important for predators associated with xeric habitats (Punzo, 1998a; Punzo and Henderson, 1999). In this study, the spiders A. hentzi and M. formosipes were collected in the Chihuahuan Desert, although M. formosipes can be found in more mesic habitats. The insects R. hesperus (termite) and one group of the cricket A. domesticus were collected from xeric habitats as well. Crude fat composition also varied among the arachnids and insects sampled in this study (Table 2). This may be due to differences in food procurement ability or reproductive status, although all of the arthropods were collected at the same time of the year. It is also interesting to note that some larval insects, including the beetle P. punctata, the moth P. pandorus, and the butterfly P. charitonius), contained a higher fat content than adults of the same species. This is in agreement with previous studies which showed that larval waxworms (Galleria mellonella) and mealworms (Tenebrio molitor) and the alates of ants and termites had significantly higher fat content than adults or workers (Redford and Dorea, 1984; Pennino et al., 1991). This may be due to the fact that the larval stage of holometabolous insects is concerned primarily with feeding and growth, whereas the adult stage is associated primarily with dispersal and reproduction. In the case of ants and termites, the alates frequently fly over considerable distances in their search for new colony sites and require significant food reserves. Because the caloric value of fats (9 kcal/g) is higher than proteins and carbohydrates (4 kcal/g) (Scriber and Slansky, 1981; 89 PUNZO—NUTRIENT LEVELS—INSECTS AND ARACHNIDS No. 2 2003] gl 0 + TE ce + TTI 10 + £0 20 + £9 obit + €9P qo9 + TCO (TI) (Sinpe) 40JDINAIS DULOSDID) (sapjaoq punois) sepiqeied (sopJo0q) eiaydoajog V LOUSNI qvO+ CE 97+ VOI 10+ 70 eel + LL qo $ + LYVE qvi9 + € 8S (pL) (eepiuoydAjayL) snajunsis snjoosdosysp yy (suotdioos diym) 18Adoi qQsO+ VE 61+ TIT cO0 + 90 vil + ¢9 qe L + 6 6€ gd l + CS9 (OL) (oepryfeysonowumy) iuosduijs vjjayrasjouuup (suoidioos pulm) oesnjIjos gOT+SE€ Tc + vol cO + 90 el I + L9 519 + OSL q99 + 979 (OI) (evpraofaeA) 10119048 snuojI0ANADg glLO + Cf ce + O6ll 10 + VO 29 O + 8S VS + £ 0S qo 8 + 719 (TI) (oeprying) IZjuay saploansjuay (suotdioos) epruordios¢ 970+ CS QG A= {GG 10+ 70 29 0 + 66 got + COV ql't + 1S9 (TZ) (eepistMoy]) sadisouliof saplouawnsi py Gl = EG MS ss €0 + 90 166 = 10)! ql V + 8'E7 156, = 7 OL (Q1) Sadijioid uoiplioy I IC+CEL 97+ CEI 10+ $0 el I + 79 qe & + ELE go 9 + 1C9 (TZ) (CVPUPLOYL) SUPIIDLU SUD]IEPOAIDT we 1 + 6S ce +7 Il cO + LO gl 0 + SE go e + LIV eo 8 + $99 (OL) (ovptsoydessy) ZJuay vuljadouoydy vO = CS TE F SEL 10 = ¢0 ol + 6V Lt = 8'Sp Gh S EVO (pI) (eeptdoAxQ) snoijos sadotxC qgvO + OF vo+rLIl TO + $0 evil + 8S 99 €.+ 88 gov + 819 (OI) Snuoylind psoyro4[ eLO+ 1S cl +66 10 + 70 qo l + 67C qvb + VOC 209 + £'£9 (Q) (QBpIsooAT) sisuauljo1v) DUSOH] el 1 + OV 97+ SSI c0O + 60 es | + 88 roe + € 8l eV 8 + SLO (TI) (oepHeIst4) SoUsaqiy DiuBIINYyNY qQsO + It yvo+ell 10 + 70 ro O + OL go S$ + © OV qe 9+ 8S (6) (sepidoutag) vsouids sidouiag qQ“vO+ et 60 + CCI 10 + V0 elLI+vVS 07 + V LY qt 6 + 809 (ZZ) snsoidps snuat) we | + L9 LO + ¢ el 10 + $0 ro O + 8S GLive alae gl lL + S'6S (OI) (eeptuayD) VIDIJI8VS DUaYI_AII ve Il +68 Te + 6ST cO0 + 90 el C + 18 lt + CLS rl + L99 (Q]) (oeprouery) iuDinn adols.ip (siapids) ovouvly VdCINHOVaV ysVv E(GIN N-HdV UdSO.IIU [PIO], Ww] opnio (%) Jae A sotoods Joneyy Aig 1U0010g ‘(aqy asIa}ap [ennou) ON ‘(ussontu Joqy yUdsIO}0p ploe) N-4AV ‘(SO'O > d) Wworajip Apuvoyrusis ore sydiiosiadns yUdIOJJIP YIM ULUNTOS & UTYIIA Sse]D JUOLNU YOR JO] saseys QIAO oft] puv satoodg ‘sasoyjuosed ul UMOYsS (SS) Sozis o[dueg “q's | SURO sv possoidxo vIRG ‘SprlUyoRIY pUL s]OOSUT SNOLIVA JO UOTTISOdWOS JOLIN “7 ATAV, [VOL. 66 FLORIDA SCIENTIST 90 qe O + FC VC+ CII c0 + LO eL Il + 60 LV + 80S als 42 SG (ZI) (sympe) sypuiusa) vjpydar0yjuvop (ssnq po}00j-Jea]) seplol0oD eiajdiwey qvO + 6€ ve +Lvl cO + 60 200 + 6L eo | + VOT el V + © 89 (ry) (sinpe) saspsounjau vplydosoiq (sory way) sepytydosoiq (sary) vindiq go O0 + 9TC CI + 80 10+ 90 wWO+ 1S 397 + 160 ae $ + VIO (OT) (sijnpe) qe 0 + 87 lee CAOIL TO + 90 elas CS XG os Shy qo See 6S (Z1) (sydurku) vunrisawn vjounjdisad (YOVOTYD0O UROTIOWY) sepIneTg BLO Le CC ert EOce 70 Ses ASG GOS 7 CHA) (91) (sydwiAu) voupwias vjjaing (YOROTYIOS URULIAD) sepryjolelg viaydoAjoIiq gol + £€ SiG SGI CO + SO wls+eEL gl € + VLC go S + 19 (9Z) (si[npe) gvO+ OF Te+ Cel 10+ ¢€0 Eb | cee) gvl + le quilss= (C.v9 (PE) (QBAIL]) 10]1]0lU O14qaua J qe 0+ OE ce + 8Cl TO + €0 FOES 9 qo S$ + 6'6C qvl + © 19 (TI) (synpe) vaiupajdsuuad sajvqo]p (SplUOLIqoud}) SepluoLIqous |, goO + CE Li+ 31 CO + SO evo C + 99 ene AP eG go $ + 709 (y1) (sinpe) qh I + 9 €€+ 9Cl 10+ 70 eol + OL qvit + BLT ae 8 + 19 (OL) (eeAre]) YIDJIUNd YJoUplad gvO+ CL Te + Cl 10+ £0 200 + 89 sesGea28 OS q99 + 619 (ZZ) (@BAIeT) sMydj1) Sajspudq (sapJa0q qeieos) seploeqeieos qe l + GE LC + 8 II 10+ 70 es 0 + 99 387 + 8697 qeelee 19 (pI) (synpe) 1Zapunsaf snoAT (Saq}o0q posUIM-Jou) sepIoA'T qol + CE CCT + 11 £0 + L0 el Le 69 5 V2 22.8 OV qg8'S + 66S (OI) (synpe) tauyod snandous0) (saqjooq WIOYsUOCT) sepIoAquuesad qvO+ CE 97+ OTT C0 + 50 vel +Ll9 ol 9 = CS 6P gb + 819 (OL) (sirnpe) gl I + 67 Ic + 8 Ol 10+ 70 el + 6S 386 + TPS go 9 + T09 (QO) (QeAIe[) winjpsajgo uosydowg YysVv HaN N-ACV UdsOMU [eIOL, ye} opnty) (%) JCM satsadg Joneyy Ag Wwsd01eg ‘ponunuod °7 ATAV L 91 PUNZO—NUTRIENT LEVELS—INSECTS AND ARACHNIDS No. 2 2003] PL Se 1G ve + 89 TO + $0 Sa eee Cas HOG Fa 28 + 6°89 (v7) (sinpe) simuassp snqpc4sy 200+ 77 Te + o8I TO + 90 el 1 + 68 2 C + 90C eV +9OTL (ZE) (siNpe) snoisawop vlayop (S}OYOLID) oeprTTAID el | + C6 Cc + 6SI c0 + 90 el C+ 98 ec | + SOL 2h 9 + 699 (OT) (sydurku) panosqo vosa001S149§ (sroddoyssei3) oepipLioy viajdoyuO qvO+ TE 61+ LOI c0 + 70 ee O+CL gd C + 8 6E ql v + © 8S (ZI) (sinpe) viusns vdosdayD (ssuIMooR]) septdosAryD elojdoinoN ql I + 87 Tc + 91T 10 + £0 280 + 69 98 6 + LSS q?v = T19 (OT) (9eAre]) qgvO + TE 91 + 8Ol 10 + V0 eo + BL SF + VIS qd t + 66S (8) (synpe) snuopund vaopung (syjou xuryds) oeprsuryds gl0 + ST 91+ ETT 10+ €0 veel +VS 8 + ESS qv S + €C9 (VI) (9B Arr]) qLIl +e 6¢ + VCI 10+ 70 23 | + 89 ov & + VIS ql v + 809 (OT) (synpe) smiuojlupys sniuoseH (saryiayng v1gdZ) sepItuosTToH viajdopidaT eo O+ TS el + L91 €0 + 60 28 0 + C6 eh CS + SLI ot + VLI (ZZ) snsadsoy sautsaynoyoay SepHuLo}OUulyYy viajdos] qo 0 + 67C Tl + ZOl 10 + £0 vol +vel ql t + VOV qe & + C8S (PI) (SiNpe) srmpnoiuvs UadIgLT (SBpeoId) BepIpeoty viadowoy YsSV Han NACV uosoOMU [eI0], yey op) (%) JoIeM saroedg Jone Ald 1U9010g ‘ponunuoy °7 aTaV |, 92 FLORIDA SCIENTIST [VOL. 66 Simpson and Raubenheimer, 1995), insectivores could maximize their caloric intake and energy budgets by selectively feeding on larval insects when they are available in the field. In captivity, growth rates could be enhanced by utilizing diets high in non-toxic larval insects. In addition, when oxidized, fats provide twice the amount of metabolic water than carbohydrates (Downer and Mathews, 1976) thus enhancing the dietary source of water. This may be especially important for insectivores found in xeric habitats. Among the arachnids, the spiders A. aurantia, C. captiosus, T. parthenus, and O. salticus, and the scorpions C. hentzi and P. gracilior, contained crude fat levels approaching the highest concentrations found in some insects (Table 2). Total nitrogen values ranged from 2.9—10.1% dry matter (DM) for arachnids, and 5.1—9.2% DM for insects (Table 2). Only 3—9% of total nitrogen was measured as chitin-bound nitrogen (ADF-N). This is in agreement with the 3—8% range for ADF-N reported for other species of insects by Barker and co-workers (1998) and Studier and co-workers (1991). Insects have been described as a good source of dietary nitrogen; studies have reported nitrogen values ranging from 3—19% DM in several orders of flying insects (Studier and Sevick, 1992), and 14-23% DM in the cocoons of several lepidopteran species (Studier et al., 1991). Barker and co-workers (1998) reported values ranging from 6.9-8.3% DM for several species of mealworms, 8.8—10.3% DM for juvenile and adults, respectively, of the cricket, Acheta domesticus, 6.6% for the waxworm Galleria mellonella, and 9.0% DM for the fruit fly, Drosophila melanogaster. Ash values ranged from 3.1—8.9% DM in arachnids, and 2.3—9.2% DM in insects (Table 2). Ash is an index of dietary mineral content, and previous studies have reported similar ash levels in other species of insects (Scriber and Slansky, 1981; Studier and Sevick, 1992; Barker et al., 1998). NDF, an index of dietary fiber (in the cell walls of plants and in chitin) com- prised 9.9-17.4% of DM in arachnids, and 10.7—18.5% of DM in insects (Table 2). This is in agreement with values ranging from 12—19% reported for other insect species (Frye and Calvert, 1989; Pennino et al., 1991; Barker et al., 1998). Although some small mammals can digest up to 20% of chitin (Allen and Oftedal, 1989), chitin is typically difficult to digest. However, indigestible chitin can play an important role in nutrient absorption in the gastroinestinal tracts of a variety of insectivores (Van Soest, 1994). The concentrations of selected minerals and trace elements in the arachnids and insects analyzed in this study are shown in Table 3. Significant differences were found between the various taxa for calcium, magnesium, phosphorus, copper, iron, manganese, and zinc. Calcium requirements for birds and mammals range from 0.4—2.5% (Robbins, 1993), with lower requirements reported for insects (Nation, 2002). Only the cockroaches B. germanica and P. americana, the hemipteran A. terminalis, the homopteran T. canicularis, the neuropteran C. carnia, and the orthopterans S. obscura, A. domesticus, and G. assimilis meet these requirements. In general, insects have been reported to be inadequate sources for dietary calctum (Frye and Calvert, 1989; Keeler and Studier, 1992), and all of the arachnids tested in this study as well as most of the insects had low calcium content. No. 2 2003] PUNZO—NUTRIENT LEVELS—INSECTS AND ARACHNIDS 93 All of the arachnids and insects analyzed in this study exhibited Mg and P levels (0.03—0.15% DM and 0.3—0.6% DM, respectively) adequate to meet the dietary needs of birds and mammals (Robbins, 1993) and most insects (House, 1974; McFarlane, 1991; Nation, 2002). Similarly, the trace element requirements of most vertebrates and insects (ranging from 1.0—6.0 mg/kg Cu; 2.4-47.5 mg/kg Mn; 17— 180 mg/kg Fe; 7.1-30.0 mg/kg Zn) (Gordon, 1959; Waldbauer and Friedman, 1991; Robbins, 1993) were met by the taxa sampled in this study (Table 3). Concentrations of vitamin E and A were quite variable among the taxa (Table 4). In spiders, vitamin E concentrations ranged from 43.2—201.2 IU/kg, whereas vitamin A levels ranged from144.5-426.3 IU/kg. Scorpions and whip scorpions had significantly lower levels of vitamin E as compared to the other arachnids. In insects, vitamin E concentrations ranged from 17.7—512.5 IU/kg, and vitamin A concentrations from lows of 11.4 IU/kg in the fruit fly D. melanogaster, and 21.7 IU/kg in the termite R. hesperus, to a high of 803.2 IU/kg in adults of the mealworm, 7. molitor. Vitamin A requirements for domestic carnivores and wildlife range from 6000—15,000 IU/kg while vitamin E requirements range from 20—80 IU/ kg (National Research Council, 1985, 1986; Robbins, 1993). All of the taxa anal- yzed in this study fall well below these levels, indicating that arachnids and insects may provide only a limited dietary source of vitamin E and A for insectivores. Minimum vitamin requirements of insects are poorly understood and are thought to be quite variable depending upon the species and life cycle stage (House, 1974; Nation, 2002). Vitamin E is required for spermatogenesis in male crickets of A. domesticus (House, 1974), and by some female insects to attain sexual maturity and oviposit eggs (Nation, 2002). Vitamin A is required by insects for normal pigmentation and eye function, and has been shown to accelerate growth in the fly Agria affinis and the silkworm Bombyx mori (Waldbauer and Friedman, 1991; Nation, 2002). In conclusion, these data provide a baseline for understanding the nutritional quality of arthropods found in the diets of naturally-occurring insectivores. The nitrogen, ash, minerals, trace elements, and dietary fiber content of arthropod tissues can be quite variable between species, and may reflect seasonal variations in micronutrient environments (Keeler and Studier, 1992). In addition, insects are known to be poor sources of preformed vitamin A and E (Allen and Oftedal, 1989; Barker et al., 1998; Finke, 2002) leading some to suggest that insectivores may be able to convert carotenoid precursors to help meet the dietary demand for this nutrient (Dierenfeld et al., 1995). Although the effects of dietary deficiencies in vitamin E on insectivores are poorly understood, it is a well known antioxidant and is involved in cellular homeostatic processes (Robbins, 1993; Nation, 2002). In captivity, insectivores are typically provided with insect diets that are supplemented with calcium and vitamins A, D, and E, in amounts that vary according to the types of invertebrates in the diet (Finke, 2002). More information is required to understand how wild-ranging insectivores may compensate for nutrient deficiencies that may vary seasonally. ACKNOWLEDGMENTS—I wish to thank M. Chapla, C. Ihlo, and T. Punzo for assistance in the chemical analyses of insects, C. Bradford (Lawrence Laboratories, Vernon, IL) for access and use of equipment for [VOL. 66 FLORIDA SCIENTIST 94 gO El + 8'6CI aoc + 19 q9'T # ESE GW cael hy gee I AYA) gel 0 ldauod “2 eel @ LEl gl 0 + 6S qv + SLE 26 + 99T q0v'T aloo qcl'0 (Vv) ql Sl ee Sel qvl + €9 6 SOS eee Ul ace I qv70 ql l'0 (J) winjps911190 “CO Gevl +c 9OET A910) = 67S li SES el bv + £91 ie Sc 0 qv1'0 1OJDINAIS “J viajdosjoa V.LOASNI gO El + LVI ql0 + 19 qe S + €0P SG ee Ml 26L'0 eS 10 Ll 0 snalun3is "Wy 13Ado1q, qf Ol + EVIT qo 0 + 67 Ge = Ave ely + SOI gee I qlZ0 qv1'0 1uosdujs “y oesnjljos aS VI + 90EI A910) VL S aviv == ILE aoe = 81 GEG qb7'0 Acs 4ONLIDAS q06 + CPTI qo I + 19 ASS ee ec + VOT qSe I 0c 0 q€l'0 Izjuay *D epruordioss qvOl + 9TII 04 LS al€ + VOE 566 Sig KEG| eL1'0 O10 sadisousof JW oO IT + S891 re. + WOt 96 + 9SEI eL beesOrrl 2890 el 0 610 sadyoid * J aly = AWE) ef bv + Tb? el = CNG BG RAGE! ecL'0 eel 0 elZ0 SUDIIDUL “'T a8'SI + 9'VCI q60 + LS ql’ S * OSE YE FEEL ALG eV10 ql l'0 IzZjuay *V aS El + €'601 qvl + 19 GS aah 17s Ae (SS qlew KGS) qv1'0 SNI1DS “O aC | HOnceee Ll qv'9 + OTE NEG al ASG 610 acLO snuayiiod * qe VI + TITEL 6G NG as S + POE oC Ce GUL ace I qlZ0 qvl‘0 SISUUIJOADD * HT ql €l + 68II gl 0 + 19 play =e Lave LO(G Ba SIl q6C T qlZ0 qe l'0 sypUsaqgly “Yy AGO = SISA alc # 69 vse PIs ay cee 91 ql I qvT'0 qvl'0 psouids *q iS SONG! Aa 208, S BGiG) BrGSE AEE OP ql VT 9610 ql 10 snsoudos “Dy el €l + 6891 280 + Tv oy a LVEl sOiGae TSI 2650 LTO axa) DIDIN8DS JW ec 9l + SSLI wleGe ene 9G eis = VILE! a7 Coe LT e8L'0 280°0 GOW DijuDAnND “py ovouvly VGINHOVUV (33/3) UZ (33/3u) UY (3¥/3u) 24 (3¥/8ul) nD (%) d (%) 3N (%) &D ,Soroedg SUOTJVIJUSOUOD [ePIOUTLAY (SO'O > d) WasayJIp AMuLoyTUsIs ore s}dtiosiodns JUaIoIJIp YIM SULUNTOS UTYJIM SSP[D JUSLNU YORI OF saseys a[OAO ajl] puw satsedg ‘q’S | suvoW JO % Sb passaidxa sonjeA °Z a qe], Ul possi] se OWNS oY} oe SazIs a[duresg “s}OaSUT PUR SPIUYORIe IATILIUISIIGAL UT SJUIWUD[O IdeI] PUL S[PIOUTUIOIOVU PoJdoJ9G “¢ ATAV 95 PUNZO—NUTRIENT LEVELS—INSECTS AND ARACHNIDS No. 2 2003] J Age] Ul parst] se exe] | ee OL + LSI Bey? se (LS go6 + © 6LI ol Ct + 16 »eVl 0 eo s0¢ I STJIVUISSD “£) xD tl + SOF! 569 + 6ST qe IT + I Col 3060 + 88 208 O 2910 58C | SNITSIWUOP “Y soak = 1 C9L ASL == (SOS gl LI + OL8T ol I + $6 20L 0 al JL Als |! 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ST]DULUAI] “Y vio diwoy 29 OI + C IST ANG == '2 JL) ol IC + £ 867C 501 = C8 alE\E 1 eS 1 O qvl 0 LIJSDBOUDJIU “(J viadiq vee SI + VLSI 388 + V8 AG WAS = Sell 30+ 76 ell 0 291 0 JG | DUDIIAIUD *d we Cl + (CII »oL9 + 90D el SC + S691 ol + 78 2180 2S | 0 ac Gal DIUDULIIS “J viaidoAqoiq qe tl + 6 6701 qe l + V9 ql 9 + 69€ vee + 8 OL qOt | aC O qcl 0 (Vv) qo Il + S VEL gl 0 + 89 gl bv + L8E ey © + SLI ql Vl g8c 0 gel 0 (J) Hojo *T gd Ol + LIEl gh Il + €9 goo + LSE wt + OSI g8t I q9C 0 qt lO poiupapasuuad “pv go 8 + S8CI gdO0+ 6S qd t + SCE leg == Ol gee. | gcc O qvl 0 (Vv) qd Il + 8 0EI qo | +99 qoS + GOL et + CLI qaeul ave 0 qt 1 0 (1) pyojound ‘d SL + 687Cl gL Il + 79 qgB& + OVE vo + LOL Gaal aoc O gel O Sg Mae q9 Ol + S CEI gh I + $9 gl + LEE vol + 8ST qS& | glc 0 ql l 0 IZopud.soaf “7 (3¥/3u1) UZ (3¥/3W1) UIA | (33/3) 24 (3y/3u) nD (%) d (%) 3 (%) &D (Soloeds SUOTIBIJUQOUOD [BIOUTIAY ‘ponunuoy “¢ aTaV 96 FLORIDA SCIENTIST [VOL. 66 TABLE 4. Fat soluble vitamins in representative arachnids and insects. Sample sizes are the same as listed in Table 2. Values expressed as means + S.D. Species and life cycle stages (for each vitamin within a column with different superscripts are significantly different (P < 0.05). Species’ ARACHNIDA Araneae A. aurantia M. sagittata C. captiosus D. spinosa K. hibernalis H. carolinensis T. parthenus O. salticus A. hentzi L. mactans T. pictipes M. formosipes Scorpionida C. hentzi P. gracilior Solifugae A. stimpsoni Uropygi M. giganteus INSECTA Coleoptera C. scrutator O. obliteratum (L) (A) C. palmeri L. ferandezi D. titylus P. punctata (L) (A) A. pennsylvanica T. molitor (L) (A) Dictyoptera B. germanica P. americana Diptera D. melanogaster Hemiptera A. terminalis Homoptera T. canicularis Isoptera R. hesperus Lepidoptera H. charitonius (A) (L) Vitamin E (U/kg) D012) Ons 568) Be Se? Wil a2 5? 64.3 + 4.9> 68.5 + 7.9° 102:4 alge se 92.4 + 8.8° 69.5 + 6.7° AB ONE H3o 151.8 + 5.6° 134.7 + 6.3° TD Aor B10 548 35.2 = 408 62.5 + 8.1° 2046.8" Zi On SalG A) a= 54° 19.3 + 6.3! 305) = 398 DR Agia AVS ANG as 6.0% 39.4 + 6.63 (gp as 62h AN) 2) 6a" YG de A 37 7c JOM a 923 = 8.4? DB 6 I+ 36.7 + 6.6% A032 aA Vitamin A (IU/kg) A012 £199.37 197.6 + 19.3° 307.6 + 27.4° 144.5 + 20.5” 201.5 + 19.4? 239.7 + 30.5° 219.9 + 18.6° 152.3) owe 291.1 + 23.4° 441.3 + 20.5? 426.3 + 31.4? 266.8 2 1g 42 234.6 + 18.2° 228.8 + 21.5° 378.2 = 05,54 247 8s 2nSe 725.) = Aan 509.6 + 41.7! RWG t= Se 417.7 + 18.6° 353.7 + 26.89 684.2 + 40.1° 428.6 + 35.8° 209.5 + 12.6° 657.4 + 22.6° 771.8 + 33.68 803.2 + 44.78 438.2 + 20.6° 425.5 = 24.16 11.4 + 2.68 562.2 + 41.1! 548.7 + 28.4' 217 Soe 109.3 + 10.2' 161.4 + 114° No. 2 2003] PUNZO—NUTRIENT LEVELS—INSECTS AND ARACHNIDS 97 TABLE 4. Continued. Species’ Vitamin E (IU/kg) Vitamin A (IU/kg) P. pandorus YD 2 DES 104.3 + 13.6 Neuroptera C. carnia AAiecteiife BO7sie Si ie Orthoptera S. obscura Gif sy lel Se 739.8 + 36.42 A. domesticus 1Ogp == NOB” 754.6 + 64.28 G. assimilis IOLA z= oe TIDE se AG SE ? Taxa as listed in Table 2. mineral and vitamin analyses, and J. Koehler, D. Martin, and anonymous reviewers for comments on an earlier draft of the manuscript, and B. Garman for consultation on statistical analyses. Financial support was provided by a Faculty Development Grant from the University of Tampa. LITERATURE CITED ALLEN, M. E. AND O. T. OFTEDAL. 1989. Nutritional consequences of insectivory. Pp. 416-417. Jn: Proc. Fifth Internatl. Theriol. Congr., Rome [Abstract]. AOAC. 1996. Official Methods of Analysis of Aoac International. 16th ed. AOAC International, Gaithersburg, MD. BarKER, D., M. FITZPATRICK, AND E. S. DIERENFELD. 1998. Nutrient composition of selected whole invertebrates. Zoo Biol. 17:123—134. Curio, E. 1976. The Ethology of Predation. Springer-Verlag, Heidelberg, 250 pp. DIERENFELD, E. S., D. BARKER, J. WALBERG, AND H. C. Furr. 1995. Vitamin A and insectivore nutrition. Verh. ber Erkrg. Zootiere 37:245—249. Downer, R. G. H. AND J. R. MATHEwS. 1976. Patterns of lipid distribution and utilization in insects. Am. Zool. 16:733-745. Exuis, R. L. 1984. Meat and meat products. Pp. 431-443. In: WiLLiaMs, S. (ed.). Official Methods of Analysis of the Association of Official Analytical Chemists. Assoc. Analyt. Chem., Arlington, VA. Finke, M. D. 2002. Complete nutrient composition of commercially raised invertebrates used as food for insectivores. Zoo Biol. 21:269-285. Foe.ix, R. F. 1996. The Biology of Spiders. Oxford Univ. Press, NY, 330 pp. Frye, F. L. AND C. CALVERT. 1989. Preliminary information on the nutritional content of mulberry silk moth (Bombyx mori) larvae. J. Zoo Wildlife Med. 20:73-75. Gorbon, H. T. 1959. Minimal mineral requirements for the German roach, Blatella germanica Linnaeus. 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Live mass, water concentration, nitrogen, and mineral levels in some insects from south-central lower Michigan. Comp. Biochem. Physiol. 103:579-595. , J. KELLER, AND S. H. Sevick. 1991. Live mass, water content, nitrogen, and mineral levels in some insects from south-central lower Michigan. Comp. Biochem. Physiol. 103A:579-595. TAYLOR, S. L., M. P. LANDEN, AND A. L. TappeL. 1976. Sensitive fluorometric method for tissue vitamin analysis. Lipids 11:530—538. van Soest, P. J. 1994. Fiber and physiochemical properties of feeds. Pp. 140-155. Jn: vAN Soest, P. J. (ed.). Nutritional Ecology of the Ruminant. Cornell Univ. Press, Ithaca, NY. WALDBAUER, G. P. AND S. FRIEDMAN. 1991. Self-selection of optimal diets by insects. Annu. Rev. Entomol. 36:43-63. Florida Scient. 66(2): 84-98. 2003 Accepted: September 10, 2002 Biological Sciences HERBIVORY AND POSTGRAZING RESPONSE IN HYPERICUM CUMULICOLA (1,2) (1), Lars BRUDVIG AND PEDRO F. QUINTANA-ASCENCIO Archbold Biological Station, 123 Main Drive, Venus, FL 33960 Department of Natural Resource Ecology and Management, 253 Bessey Hall, Iowa State University, Ames, IA 50011 ABSTRACT: We describe patterns of mammalian herbivory and examine possible fitness consequences of herbivory on Hypericum cumulicola, an herbaceous perennial endemic to Florida scrub. We noted the presence or absence of mammalian herbivory on 1841 H. cumulicola individuals, from 23 populations in two study sites. At Archbold Biological Station, we found the presence of herbivory to be positively correlated to the number of conspecific neighbors, and negatively correlated with time- since-fire. At Arbuckle Tract of Lake Wales Ridge State Forest, presence of herbivory was affected by habitat (scrub or roadside) and negatively associated with the number of conspecific neighbors. We performed a clipping treatment on naturally occurring H. cumulicola individuals to simulate mammalian herbivory. The results indicated that H. cumulicola appears to undergo compensatory regrowth following defoliation. The one-year fitness consequences of herbivory appear to be neutral although the long-term fitness consequences of herbivory on the perennial H. cumulicola can not be known from this study. We hypothesize that in addition to disturbance tolerance (through increased regrowth rate), patchy distribution and low density may reduce the impact of mammalian herbivory on H. cumulicola. Key Words: compensatory growth, Florida scrub, herbivory, Hypericum cumulicola, overcompensation HERBIVORY reduces plant biomass, and can affect growth and reproduction (McNaughton, 1983; Bergelson and Crawley, 1992a,b). In intensive grazing systems, selection pressure should favor plant individuals with traits allowing them to attenuate the negative effects of tissue loss. Belsky and co-workers (1993) grouped such adaptations as (1) strategies that allow the plant to avoid herbivory, such as escape from discovery through non-apparent, patchy distribution and chemical and mechanical defenses and (2) overcompensatory growth following an herbivory event. Compensatory response can be divided into three classes (Maschinski and Whitham, 1989): overcompensatory growth, compensatory growth and undercompensatory growth. In overcompensation, grazed plants produce more fruits and seeds than control plants. Compensation occurs when grazed and control plants produce similar numbers of fruits and seeds. Undercompensation occurs when grazed plants produce fewer fruits and seeds than control plants. Overcompensa- tory growth has been controversial, with studies in support of this phenomenon (McNaughton, 1983; Paige and Whitham, 1987; Paige, 1992, 1999) and studies * E-mail: archbold@archbold-station-org 99 100 FLORIDA SCIENTIST [VOL. 66 finding no support for it (Belsky, 1986, 1987; Bergelson and Crawley, 1992a,b; Bergelson et al., 1996). An array of compensatory responses has been documented, with undercompensatory growth and overcompensatory growth at the extremes (Maschinski and Whitham, 1989). One explanation for compensatory growth is that rapid regrowth following defoliation is an evolved response of the plant to minimize the effects of structural damage, which can come from many sources including fire, trampling, and herbivory (Belsky, 1986; Belsky et al., 1993; Rosenthal and Kotanen, 1994). A meta-analysis of the impact of herbivory on plants in different resource conditions indicates that overcompensation is more likely in high resources for monocots and in low resources for dicot herbs (Hawkes and Sullivan, 2001). This work examines mammalian herbivory on Hypericum cumulicola, a perennial herbaceous species restricted to sandy gaps in the Florida rosemary scrub. The study consists of two parts: (1) an observational study, relating mammalian (presumably deer Odocoileus virginianus seminolus and rabbit Sylvilagus flori- danus floridanus) herbivory rates on H. cumulicola to demographic parameters and environmental variables, and (2) a clipping experiment testing H. cumulicola com- pensatory response to herbivory. The objectives of this study are to explore patterns of mammalian herbivory across different populations of H. cumulicola and to examine possible fitness consequences. MeEtTHODs—Study species—Hypericum cumulicola ((Small) P. Adams) is a small, short-lived, perennial herb endemic to the Lake Wales Ridge of Polk and Highlands Counties in central Florida (Quintana-Ascencio et al., 1995). Though largely limited to gaps in Florida rosemary scrub, H. cumulicola can also be found along roads and firelanes and, infrequently, in well-drained openings in scrubby flatwoods. H. cumulicola branches from the base and grows to heights of 20-70 cm. Vegetative in the winter and spring, most plants become reproductive during the summer, growing reproductive stalks (1-17) with up to thousands of flowers and fruits per plant. Fire kills H. cumulicola individuals, but populations are able to recover through persistent seed banks and/or dispersal from nearby populations (Quintana-Ascencio et al., 1998). Fruit production, recruitment rates, and survivorship are highest for the first few years after fire, with these traits decreasing with increased time-since-fire (Quintana-Ascencio and Morales-Hernandez, 1997; Quintana-Ascencio et al., 2003). Study Sites—We conducted this study at Archbold Biological Station (Archbold) and the Arbuckle Tract of Lake Wales Ridge State Forest (Arbuckle) in south-central Florida. All study sites at Archbold were in Florida rosemary scrub. We organized the Archbold sites by time-since-fire based on records of natural, accidental, and prescribed fires kept since 1967 (Main and Menges, 1997). Study sites at Arbuckle encompassed a larger range of H. cumulicola habitats. These habitats included natural (rosemary scrub and oak scrub), and human disturbed (roadside and tram). The rosemary scrub and oak scrub patches in Arbuckle were within areas burned in the last decade. However, the large size of Florida rosemary (Ceratiola ericoides), an obligate seeder, in the Florida rosemary scrub sites indicated that fire did not reach these Florida rosemary scrub patches. Rosemary scrub occurs on sandy, well-drained soils of ridges and knolls and is characterized by sometimes large, open gaps in the vegetation (Abrahamson et al., 1984). Florida rosemary (Ceratiola ericoides) often dominates the shrub layer. Other species often present include oaks (Quercus spp.), and palmettos (Serenoa repens and Sabal etonia). The sub-shrub Licania michauxii, lichens (Cladonia spp.), spike moss (Selaginella arenicola), and several herbaceous species including H. cumulicola grow in open gaps in the vegetation. Oaks (Quercus spp.), and palmettos (Serenoa repens and Sabal etonia) are dominant species in oak scrub. Though not characterized by them, oak scrub sometimes does contain scattered open gaps, which support similar vegetation as the gaps in rosemary scrub. Roadside sites were No. 2 2003] BRUDVIG AND QUINTANA-ASCENCIO—HERBIVORY 101 on active sand roads, which contain H. cumulicola populations. Tram sites lie on berms of old railroad lines. Tram sites are characterized by large gaps and a lower water table than the surrounding areas. Though the railroad tracks are no longer present, the berms now lie along side sand roads. Fire plays a major role in determining Florida scrub community composition and dynamics (Menges and Hawkes, 1998; Menges, 1999). Fires in oak and rosemary scrub are often heterogeneous, producing gaps in the unburned vegetation. Gap specialists (such as H. cumulicola) are most abundant shortly after fire, but become less abundant as shrubs and lichens increase with time-since-fire. Thus, gap specialist species residing in oak and rosemary scrub depend on fire for their persistence. Sampling methods of the observational study—At Archbold, in August 2001, we noted the mammalian herbivory on 956 H. cumulicola plants from 15 rosemary scrub patches, representing a gradient of time-since-fire (4 to 34 years after fire), patch size, and north-south distribution along the station. Within each patch/site, we sampled at least 70 individuals in a stratified random fashion along 1 m wide belt transects, if greater than 100 plants were present at the site. If fewer than 100, the entire population was included in the sample. At Arbuckle, we sampled 885 individuals from 8 sites: 2 oak scrub sites (n = 236), 2 rosemary scrub sites (n = 201), 2 road sites (n = 236), and 2 tram sites (n = 212). We recorded, for each plant sampled, maximum height, number of conspecifics within 15 cm, number of reproductive structures (flowering buds, flowers and fruits), and presence or absence of mammalian herbivory. Presence of mammalian herbivory was associated with complete branch removal. Insect herbivory was also present on some H. cumulicola individuals but was not recorded and was readily distinguished from mammalian herbivory as branches, flowers or fruits eaten by insects were not entirely removed. We conducted forward stepwise (Wald) logistic regressions to determine the significance of the association of time-since-fire, and number of conspecific neighbors (data log-transformed) to the presence of herbivory in H. cumulicola at Archbold. We conducted forward stepwise (Wald) logistic regressions to determine the significance of the association of habitat, and number of conspecific neighbors (data log- transformed) to the presence of herbivory in H. cumulicola at Arbuckle. We then tested the significance of contrasts among habitats. Clipping experiment—We selected three Archbold rosemary scrub patches with known populations of H. cumulicola and of varying time since fire (15, 8, and <1 years since fire) for the clipping experiment. Three levels of simulated herbivory were imposed on the plants between 18 and 19 August 2001, with 10 individuals sampled per treatment, per patch. Control plants had no clipping imposed, 50% treatment had one clipping made on ~half of reproductive stalks, and 100% treatment had one clipping made on each reproductive stalk. These clipping treatments mimicked the amount and type of tissue removal observed in plants with naturally occurring herbivory. We imposed clipping on a haphazardly chosen piece of stalk, at the point of the first branching event (only one stalk was present in 5 of 30 plants under the 50% herbivory treatment; clipping was imposed on this stalk). Within gaps at each scrub patch, we sampled plants along 1 m wide belt transects, running at a random distance from the edge, per- pendicular to the longest axis of open sand in the gap. At 1-m increments along the belt transect, the three closest plants (without prior herbivory) were chosen for sampling. For each sampled plant, we recorded the height of the tallest stalk (pre- and post-clipping), cumulative height of the stalks (pre- and post-clipping), and the number of reproductive structures (pre- and post-clipping). Treatments were assigned left to right with respect to the tape, in a rotational fashion. At completion of sampling, plants were enclosed in cages made of wire chicken cooping, successfully preventing the subsequent occurrence of natural herbivory. We resampled the treated plants between 15 and 17 September 2001. For each plant, height of the tallest stalk, cumulative height of stalks, and number of reproductive structures were recorded. Maschinski and Whitham’s (1989) definitions of compensatory growth involve only the differences in fruit and seed production, between grazed and ungrazed plants. This study also looks at changes in plant height, as height has been found to be the best predictor of fecundity in H. cumulicola (Quintana-Ascencio et al., 2003). We conducted univariate analysis of covariance to test for significance of differences among clipping treatments on H. cumulicola. We tested for significance of treatment, site, and their interactions 102 FLORIDA SCIENTIST [VOL. 66 TABLE 1. Coefficients of forward (Wald) logistic regression models of presence of herbivory in H. cumulicola at Arbuckle State Forest, and Archbold Biological Station. Source of variation Beta Se df P Arbuckle Constant =—O:713 0.110 1 <0.001 Tram-Road 0.608 0.283 1 0.031 Tram-Oak scrub 3.058 0.275 1 <0.001 Oak scrub-Road —2.450 0.234 1 <0.001 Rosemary scrub-Tram — 1.084 0.274 1 <0.001 Rosemary scrub-Road —0.476 0.239 1 0.046 Rosemary scrub-Oak scrub 1.974 0.229 1 <0.001 Ln(neighbors) —0.496 0.110 1 <0.001 Archbold Constant 1.023 0.144 1 <0.001 Years since last fire —0)126 0.011 1 <0.001 Ln(neighbors) 0.141 0.052 1 0.007 on change in maximum height, cumulative stalk height, and number of reproductive structures over the month-long treatment. We statistically controlled for differences in initial size using original maximum height, original cumulative stalk height, and initial number of reproductive structures as covariates, respectively. We adjusted and compared linear models describing the relationship between height and number of reproductive structures for individuals with and without herbivory (or clipping). All statistical analyses were performed using SPSS 10.1.0. ResuLts—Observational study—Across all rosemary scrub patches at Arch- bold, the presence of herbivory on H. cumulicola was positively correlated to number of conspecific neighbors within 15 cm, and negatively correlated with years- since-last fire (Table 1, Fig. 1). Presence of herbivory on H. cumulicola at Arbuckle was affected by habitat and negatively correlated to the number of conspecific neighbors within 15 cm (Table 1, Fig. 2). Presence of herbivory was significantly different among all habitats in the following descending order: oak scrub, rosemary scrub, road, and tram (Table 1, Fig. 2). Clipping experiment—Clipped plants (at both the 50% and 100% treatments) did not differ significantly from unclipped plants with respect to final height of the tallest reproductive stalk, final accumulated height of reproductive stalks, or number of reproductive structures during the one month treatment period (Tables 2-4). Final height, when adjusted by the pre-clipping height of the tallest stalk, was still not significantly affected by clipping treatments (Table 2). Similarly, final number of reproductive structures, when statistically adjusted by the initial number of re- productive structures, was not significantly affected by clipping treatments (Table 4). To test how closely the clipping regime mimicked natural herbivory in H. cumulicola, we compared growth function models describing the association between the number of reproductive structures and the height of the plant for both H. cumulicola individuals with natural herbivory and experimentally clipped individuals. There was a significant correlation between plant height and number of reproductive structures (logarithmic transformed), with 1 > 0.465 for all curves. No. 2 2003] BRUDVIG AND QUINTANA-ASCENCIO—HERBIVORY 103 Number of neighbors 90 80 O10 70 01 M2 m>2 Percentage of plants with herbivory 3 40 30 20 10 0 NX 1997-1999 1993 1986 1967-1985 Year of last fire Fic. 1. Percentage of plants with herbivory in 2001 by year of last fire and number of conspecific neighbors in Rosemary scrub patches at Archbold Biological Station. There was always overlap among standard errors of the slopes for individuals with and without herbivory or clipping (Table 5). DiscussionN—Hypericum cumulicola responded to biomass removal with compensatory growth (sensu Maschinski and Whitham, 1989), as experimentally grazed and ungrazed plants did not produce significantly different numbers of reproductive structures. Additionally, experimentally grazed and ungrazed plants did not show significantly different stalk heights. Although H. cumulicola did not exhibit overcompensatory growth, increased growth (and reproductive structure production) rate was present in clipped plants, resulting in compensatory growth. We do not see any immediate reproductive consequences of simulated herbivory on H. cumulicola, as clipping did not reduce or increase fruit yield. Though, as H. cumulicola is a perennial, the long-term fitness consequences of herbivory can not be known from this study. In previous studies, Bergelson and Crawley (1992 a,b) and Bergelson and co- workers (1996) found no evidence for overcompensatory growth following mammalian herbivory in Jpomopsis aggregata, despite previous findings which supported overcompensatory growth in J. aggregata (Paige and Whitham, 1987; Paige, 1992; 1994; 1999). Despite the contention by Bergelson and co-workers (1996) that there is no compelling evidence for overcompensatory growth in I. aggregata, or any other plant species, the debate continues to rage. Hawkes’ and Sullivan’s (2001) review indicates that resource availability differentially affects plant recovery after herbivory in monocot and dicot herbs. These authors argue that these differences among functional groups may explain, at least in part, contradictory evidence on plant response to herbivory in the literature (Hawkes 104 FLORIDA SCIENTIST [VOL. 66 © (o) Number of neighbors “NI oO OO 1 on Oo oOo Oo S2 M>2 Percentage of plants with herbivory AAS oO 30 20 10 0 Tram Road Oak scrub Rosemary scrub HABITAT Fic. 2. Percentage of plants with herbivory in 2001 by habitat and number of conspecific neighbors at Arbuckle State Forest. and Sullivan, 2001). Our present study lends support to those who argue for compensatory growth (Bergelson et al., 1996; for example), as we saw no evidence in support of overcompensatory growth in H. cumulicola. Our study raises the question of which general anti-herbivory strategies (see Belsky et al., 1993) are employed by H. cumutlicola, if any. These are grouped into strategies or circumstances that allow a plant to avoid herbivory and strategies that allow a plant to recover from herbivory. This study shows that H. cumulicola exhibits increased growth rate following an herbivory-like disturbance (clipping). Although it has been proposed that there is a resource tradeoff between herbivory tolerance and herbivory avoidance strategies (van der Meijden et al., 1988; Rosenthal and Kotanen, 1994; Strauss and Agrawal, 1999), H. cumulicola may avoid herbivory in addition to tolerating it. Apparency theory (Feeny, 1976) hypothesizes that if the distribution of a plant species is patchy, it can be harder for herbivores to find and plants may avoid discovery. This may explain a circumstance reducing herbivory in H. cumulicola, as it resides predominantly in the rosemary scrub phase of sand pine scrub, which is patchy in distribution throughout the Florida scrub ecosystem (Abrahamson et al., 1984). The observational experiment at Archbold showed a strong correlation between herbivory rates and time-since-fire, with H. cumulicola receiving the highest herbivory rates in recently burned areas. Herbivory rates have been shown to be higher in woody species in recently burned areas as herbivores favor the green vegetative resprouts that woody species grow after being burned (see for example Singer and Harter, 1996). However, one might not expect a perennial herb killed by fire and that does not have large storage organs to show this trend. Why, then, would herbivory rates be higher in recently burned areas for an herbaceous species, No. 2 2003] BRUDVIG AND QUINTANA-ASCENCIO—HERBIVORY 105 TABLE 2. Results of an ANCOVA of final maximum height of Hypericum cumulicola with clipping treatment and site as fixed factors, and initial maximum height as covariate. Source of variance df Mean square F Je Clipping treatment 2 4.5 0.8 0.468 Site 2 2.6 0.4 0.643 Initial maximum height 1 355 6.1 0.016 Clipping treatment*Initial height 2 2.8 0.5 0.623 Site* Initial height yy oe) 0.5 0.582 Clipping treatment*Site 4 10.0 ted 0.156 Clipping treatment*Site*Initial height 4 11.8 2.0 0.099 Error V2 5.8 which produces green shoots every year? One possibility is that H. cumulicola may be a focal forage species, that is, mammalian herbivores are actively seeking out H. cumulicola for consumption. If this were the case, plants in recently burned areas should be most highly consumed, as H. cumutlicola individuals are most productive and most abundant in recently burned areas (Quintana-Ascencio and Morales- Hernandez, 1997). Herbivores would concentrate their foraging in these areas. However, due to the small and patchy population sizes of H. cumulicola, it makes more sense that H. cumulicola is a supplementary forage species, with the following situation taking place: In recently burned areas, most woody species rapidly resprout new shoots (Menges and Kohfeldt, 1995), which are heavily browsed by herbivores (Singer and Harter, 1996). In addition, several herbaceous species, including H. cumutlicola, increase their densities after fire (Menges and Kimmich, 1996, Quintana-Ascencio et al., 2003). Herbivores may be attracted by all these species, but feed on H. cumulicola, once they have reached the site. As time- since-fire increases and woody species resume their normal aboveground vegetative state and herb abundance declines, herbivores are no longer attracted to the area and H. cumulicola is not consumed. A study of habitat preferences within pine flatwoods using infrared-triggered cameras indicated that white-tailed deer and all other mammals captured on film were present more frequently in a 24 months post- fire site than in an adjacent site 48 months post-fire (Main and Richardson, 2002). TABLE 3. Results of an ANCOVA of final cumulative stalk height of Hypericum cumulicola with clipping treatment and site as fixed factors, and initial cumulative stalk height as covariate. Source of variance df Mean square I P Clipping treatment y) 26.1 0.1 0.874 Site yy SMES 2.0 0.150 Initial stalk height 1 OZ 0.5 0.469 Clipping treatment* Initial stalk height 2 6.5 0.03 0.967 Site*Initial stalk height 2 190.7 1.0 0879 Clipping treatment*Site 4 89.2 0.5 0.765 Clipping treatment*Site* Initial stalk height 4 66.8 0.3 0.847 Error TZ 193.7 106 FLORIDA SCIENTIST [VOL. 66 TABLE 4. Results of an ANCOVA of final number of reproductive structures of Hypericum cumulicola with clipping treatment and site as fixed factors, and initial number of reproductive structures as covariate. Source of variance df Mean square F P Clipping treatment 2 0.2 0.6 0.524 Site 2 0.6 1.7 0.195 Initial number of reproductive structures 1 6.2 16.3 <0.001 Clipping treatment* Initial fruits y 0.2 0.5 0.630 Site*Initial fruits 2 0.3 0.9 0.416 Clipping treatment*Site 4 0.6 1.5 0.219 Clipping treatment*Site* Initial fruits 4 0.5 163) 0.261 Error 71 0.4 The presence of mammals increased to levels observed in the 24 months post-fire site after 8 weeks following a prescribed fire in the site previously 48 months post- fire (Main and Richardson, 2002). The proportion of H. cumulicola plants with herbivory at Arbuckle was higher in rosemary scrub and oak scrub sites than it was in road and tram sites. This can be looked at in two ways, which are difficult to distinguish since habitats are identical for each case. First, herbivory rates were higher in natural sites than in man-made sites. Second, there was more herbivory away from roads than near roads. The reason for this is unclear, but may be due to mammalian herbivores (deer and rabbits) favoring covered areas (such as scrubby sites) with places to hide, over open areas (such as roadside and tram sites). This study has shown that herbivory is correlated to number of conspecifics. This correlation was negative at Arbuckle and positive at Archbold, in 2001. H. cumulicola survivorship in Florida rosemary scrub has been shown to be positively correlated to number of conspecifics (1995: p < 0.001 slope = 0.369, 2001: p < 0.001 slope = 0.185; Quintana-Ascencio and Morales-Hernandez, 1997; Quintana- TABLE 5. Parameters (and their standard error) of growth functions (In y = a + b * x) of height and number of reproductive structures (logarithmic transformed) of individuals clipped (before and after a month of treatment), untreated (control), with herbivory, and without herbivory (from the observational study, vegetative individuals not included). Treatment r a S.e. b S.e. n Pre-clipped (all) 0.538 1.848 O25 0.06 0.006 90 Pre-clipped (control) 0.642 1.846 0.361 0.06 0.009 30 Post-clipped (control) 0.565 2.167 0.402 0.06 0.009 30 Post-clipped (clipped) 0.463 1.481 0.382 0.07 0.010 60 Arbuckle Without herbivory 0.643 1.012 0.113 0.08 0.003 557 With herbivory 0.565 0.693 0.210 0.08 0.005 238 Archbold Without herbivory 0.629 0577 0.129 0.100 0.003 483 With herbivory 0.465 0.126 0.207 0.104 0.006 341 No. 2 2003] BRUDVIG AND QUINTANA-ASCENCIO—HERBIVORY 107 Ascencio, unpublished data). This raises a paradox, as high density areas may have higher survival despite higher herbivory. However, neither herbivory nor conspecific density have a consistent impact on H. cumulicola survival. Instead, it appears that other microhabitat attributes are ultimately determinant of H. cumulicola survival, to the point where favorable habitat allows plants to overcome the ill-effects of herbivory and competition by conspecific neighbors. ACKNOWLEDGMENTS—We are grateful to Eric Menges for his insight and assistance throughout the course of this experiment and preparation of the manuscript. We also thank Jane Carlson, Ann Cox, Richard Lavoy, Anne Malatesta, David Matlaga, Felipe Serrano, Carl W. Weekley, and Alaa Wally for field assistance, Christine Hawkes, D. F. Martin, Joyce Maschinski and Carl W. Weekley for friendly criticism of the manuscript, and Roberta Pickert for her help with GIS. This work was supported by Archbold Biological Station, The National Science Foundation (DEB98-15370), and The Florida Division of Forestry’s Plant Conservation Program. LITERATURE CITED ABRAHAMSON, W. G., A. F. JOHNSON, J. N. LAYNE, AND P. A. PERONI. 1984. Vegetation of the Archbold Biological Station, Florida: an example of the Southern Lake Wales Ridge. Florida Scient. 47:209-250. Apams, P. 1962. Studies in the Guttiferae. Il. Taxonomic and distribution observations on North American taxa. Rhodora 64:231—242. Bexsky, A. J. 1986. Does herbivory benefit plants? A review of the evidence. Amer. Natur. 127:870—892. . 1987. The effects of grazing: confounding of ecosystem, community, and organism scales. Amer. Natur. 129:777-783. , W. P. Carson, C. J. JENSEN, AND G. Fox. 1993. Overcompensation by plants: herbovore optimization or red herring? Evol. Ecol. 7:109-121. BERGELSON, J. AND M. J. CRAWLEY. 1992a. Herbivory and [pomopsis aggregata: the disadvantages of being eaten. Amer. Natur. 139:870—8872. AND M. J. CRAwLEy. 1992b. The effects of grazing on the performance of individuals and populations of scarlet gilia, Jpomopsis aggregata. Oecologia 90:435—-444. , T. JUENGER, AND M. J. CRAWLEY. 1996. Regrowth following herbivory in Jpomopsis aggregata: compensation but not overcompensation. Amer. Natur. 48:744—755. Feeny, P. O. 1976. Plant appearance and chemical defense. Pp. 140. Jn: WALLACE, J. (ed.). Recent advances in phytochemistry, vol. 10: Biochemical Interactions Between Plants and Insects. Plenum, New York. Hawkes, C. V. AND J. SULLIVAN. 2001. The impact of herbivory on plants in different resource conditions: a meta-analysis. Ecology 82:2045—2058. Man, K. N. AND E. S. Mences. 1997. Archbold Biological Station Fire Management Plan. Archbold Biological Station. Lake Placid, Florida, USA. Main, M. B. AND L. W. RICHARDSON. 2002. Response of wildlife to prescribed fire in southwest Florida pine flatwoods. Wild. Soc. Bull. 30:213—221. MASCHINSKI, J. AND T. G. WHITHAM. 1989. The continuum of plant responses to herbivory: the influence of plant association, nutrient availability, and timing. Amer. Natur. 134:1—19. McNaucuton, S. J. 1983. Compensatory growth as a response to herbivory. Oikos 40:329-336. Mences, E. S. 1999. Ecology and conservation of Florida scrub. Pp. 7—22. Jn: ANDERSON, R. C., J. S. FRALISH, AND J. M. BASKIN (eds). Savannas, Barrens and Outcrop Plant Communities of North America. Cambridge University Press, Cambridge, MA. AND N. Kouretprt. 1995. Life history strategies of Florida scrub plants in relation to fire. Bull. Torrey Bot. Soc. 122:282-297. 108 FLORIDA SCIENTIST [VOL. 66 AND J. Kimmicu. 1996. Microhabitat and time-since-fire: effects on demography of Eryngium cuneifolium (Apiaceae), a Florida scrub endemic. Amer. J. Bot. 83:63-78. AND C. V. HawkEs. 1998. Interactive effects of fire and microhabitat on plants of Florida scrub. Ecol. Appl. 8:935—946. Paice, K. N. 1992. Overcompensation in response to mammalian herbivory: from mutualistic to antagonistic interactions. Ecology 73:2076—2085. 1994. Herbivory and /pomopsis aggregata: differences in response, differences in experimental protocol, a reply to Bergelson and Crawley. Amer. Natur. 143:739-749. 1999. Regrowth following ungulate herbivory in Jpomopsis aggregata: geographic evidence for overcompensation. Oecologia 118:316—323. AND T. G. WHITHAM. 1987. Overcompensation in response to mammalian herbivory: the advantage of being eaten. Amer. Natur. 129:407-416. QUINTANA-ASCENCIO, P. F., E. S. MENGES, AND M. E. K. Evans. 1995. Highlands scrub Fe renee Hypericum cumulicola. (South Florida Ecosystem Recovery part 1) U.S. Fish and Wildlife Service. Vero Beach, FL. , R. W. DoLan, AND E. S. MENGES. 1998. Hypericum cumulicola demography in unoccupied and occupied Florida scrub patches with different time-since-fire. J. Ecol. 86:640—651. AND M. MorALES-HERNANDEZ. 1997. Fire-mediated effects of shrubs, lichens and herbs on the demography of Hypericum cumulicola in patchy Florida scrub. Oecologia 112:263—271. , E. S. MENGES AND C. W. WEEKLEY. 2003. A fire-explicit population viability analysis of Hypericum cumulicola in Florida rosemary scrub. Conserv. Biol. Jn press. ROSENTHAL, J. P. AND P. M. KoTANneNn. 1994. Terrestrial plant tolerance to herbivory. Trends Ecol. Evol. Biol. 9:145-148. SINGER, F. J. AND M. K. HARTER. 1996. Comparative effects of elk herbivory and 1988 fires on northern Yellowstone National Park grasslands. Ecol. Appl. 6:185—199. StTRAusSS, S. Y. AND A. A. AGRAWAL. 1999. The ecology and evolution of plant tolerance to herbivory. Trends Ecol. Evol. Biol. 14:179-185. VAN DER MEIDEN, E., M. WuN, AND H. J. VERKAAR. 1988. Defense and regrowth, alternative plant strategies in the struggle against herbivores. Oikos 51:355-—363. Florida Scient. 66(2): 99-108. 2003 Accepted: September 13, 2002 Environmental Chemistry EFFECT OF SHEAR FORCES ON THE RELEASE OF BREVETOXINS FROM KARENIA BREVIS (2) (3) DEAN F. Martin“)*, ROBERT P. CARNAHAN, AND JOSEPH J. KRZANOWSKI ‘Institute for Environmental Studies, Department of Chemistry, College of Engineering, Department of Pharmacology and Therapeutics, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 ABSTRACT: The forces associated with a culture of Karenia brevis with a magnetic stirrer were calculated and related to the release of toxins by the affected organism. Even under seemingly mild conditions (3.5 rpm with a 2.5 cm stirring bar) enough shearing energy was provided to release toxins. Parameters calculated were: the Reynolds Number, tangential velocity, mean velocity gradient, and the power. Key Words: Red tide, Karenia brevis, HABs, Florida, Reynolds Number RED TIDE is the discoloration of water in the marine environment associated with the proliferation of organisms, and is a world-wide phenomenon. In Florida, red tides are associated with the unarmored dinoflagellate Karenia brevis (formerly Gymnodinium breve Davis or Ptychodiscus brevis). Typically the outbreaks have been observed on the west coast of Florida from Cape Sable to Cape San Blas. Blooms of Karenia brevis have been associated with mass mortalities of marine animals, more than 100 species having been identified (Steidinger and Ingle, 1972; Steidinger, 1983; Steidinger and Melton Penta, 1999). The dinoflagellate causes deaths directly through the production and release of neurotoxins called brevetoxins (Steidinger and Ingle, 1972; Lin et al., 1981; Baden, 1989) and indirectly through oxygen deprivation when large numbers of the dinoflagellates die (Simon and Dauer, 1972). Presumably, the brevetoxins are released when K. brevis cells are destroyed. It has been a matter of conjecture as to the conditions under which this will occur. Heavy metal ions, notably from copper salts, can destroy K. brevis cells (Rounsefell and Nelson, 1966). Available evidence showed that allelochemicals can account for the destruction of K. brevis cells (Taft and Martin, 1986; Martin and Taft, 1998). And presumably physical effects could be responsible. The release of toxins in the surf, for example, has not seemed reasonable, considering that the surf on the west coast of Florida, in contrast with the east coast, is not considered to be a high energy surf. The present study examines the forces involved when a culture of Karenia * E-mail: dmartin@churnal.cas.usf.edu 109 110 FLORIDA SCIENTIST [VOL. 66 TABLE 1. Summary of calculated parameters for stirring of Karenia brevis culture*. Parameter Calculated value Reynolds Number 400 Tangential velocity 7 cm/sec Mean velocity gradient 28 sec! Power 2.19 x 10°“ ft-Ib/sec * 50 mL culture in a 250 mL Erlenmeyer flask stirred with a 2.5 cm bar at a rate of 3.5 rpm. brevis was subjected to mild stirring with a magnetic stirrer. Previous research (Derby, 2002; Derby et al., 2002) demonstrated toxin release under these mild conditions. Thus, it seemed pertinent to calculate what forces were involved under these experimental conditions. MetTHops—Standard methods (Streeter and Wylie, 1985) were used to calculate the various parameters, given the following characteristics of the experiment. A 50-mL sample of a culture of Karenia brevis was placed in a 250 mL Erlenmeyer flask equipped with a 2.5 cm magnetic stirrer and stirred at the rate of 3.5 rpm. The base of the flask was 7.0 cm in diameter, and the height of the medium was 1.6 cm. Toxicities of control (unstirred) and test samples (stirred) had been tested using a Microtox® 500 system (Derby, 2002; Derby et al., 2002). RESULTS AND Discussion—The calculated parameters are listed in Table 1. Certain general comments seem appropriate. First of all, the Reynolds Number is used in fluid mechanics as a criterion of laminar flow. The number is the ratio of pvd/t of the inertial force pvd to viscous force tt, where p is the fluid density, v is the velocity, and d is a characteristic of the medium (Streeter, 1966; Streeter and Wylie, 1985). In a pipe, laminar flow would be characterized by a Reynolds value of less than 2000 and turbulent flow by a value greater than 3000 (Streeter, 1966). The calculated value of the Reynolds Number in our case was 400, which is diagnostic of a comparatively low degree of laminar flow. In contrast, the tangential velocity of 7 cm/sec is comparatively high and indicates a degree of shear force, despite the casual observation that a stirring rate of 3.5 rpm with a 2.5-cm magnetic stirrer does not seem to produce a visually impressive stirring rate. The casual observation is misleading, however, and the significant degree of shear force is confirmed by the mean velocity gradient. This parameter is a measure of mixing, and the calculated value was 28. It is recognized that this value is low in comparison with values of the order of 200, which are fre- quently encountered in water treatment coagulation situations, but it is a signi- ficant value, especially when taken with the values of the two other parameters. Finally, the power level, 2.19 x 10 * ft-lb/sec is quite low. In summary, the calculations of the parameters listed in Table 1 indicate that laminar flow occurs with a degree of shear force of comparative low power that was sufficient to cause release of brevetoxins in separately reported experiments (Derby, 2002; Derby et al., 2002). Specifically, we measured the effect of a culture of No. 2 2003] MARTIN ET AL.—SHEAR FORCES AND BREVETOXIN RELEASE et Karenia brevis on the bacterium Vibrio fischeri using a Microtox™ analyzer (Derby et al., 2002). Non-stirred cultures provided a toxicity value of —20 + 0.15% (the minus sign is indicative of stimulation of growth), whereas the cultures that were stirred (as described in Table 1) for 24 hours, had a toxicity value of 45 + 1%, in- dicating that half the bacteria were eliminated in a five-minute test. Thus, while the power level was low, the shear effect was evidently significant, and allows us to understand the result more clearly. Other workers (Hemmert, 1975; Asai et al., 1982) have noted that red tides in the near-shore environment are associated with such unpleasant respiratory effects as non-productive cough, asthma-like symptoms, air hunger and the like, associated with release of brevetoxins and conversion to aerosols. The process whereby the red tide cells are destroyed remained uncertain, and perhaps still does. However, the action of fish gills could be consistent with laminar flow and shear effects such as we have observed and report here. On the other hand, when Karenia brevis cells are in a wave that is washing ashore, it is not so evident that the laminar flow conditions match those we have described, and further consideration of this matter seems in order. ACKNOWLEDGMENT—We are grateful to Mrs. Barbara B. Martin for serving as Editor for this paper. LITERATURE CITED Asal, S., J. J. KRZANOWSKI, W. H. ANDERSON, D. F. Martin, J. B. Potson, R. F. Lockey, S. C. BUKANTZ, AND A. SZENTIVANYI. 1982. Effects of the toxin of red tide, Ptychodiscus brevis, on canine tracheal smooth muscle: a new asthma triggering mechanism. J. Allergy Immunol. 69:418-428. BADEN, D. G. 1989. Brevetoxins: Unique polyether dinoflagellate toxins. FASEB J. 3:1809-1819. DersBy, M. L. 2002. The Study of the Allelopathic Agent, Nannochloris sp., Interaction with the Florida Red Tide Karenia brevis. Dissertation. University of South Florida, Tampa, FL. , M. GALiiano, J. J. KRZANOWSKI, AND D. F. Martin. 2002. Studies of the effect of ep-APONIN from Nannochloris sp. on the Florida red tide Organism Karenia brevis. Toxicon, in press. HEMMERT, W. H. 1975. The public health implications of Gymnodinium breve red tides, a review of the literature and recent events. Pp. 489-497. Jn: LoCicgro, V. R. (ed). Proc. First Intern. Conf. On Toxic Dinoflagellate Blooms. Massachusetts Science and Technology Foundation, Wakefield, MA. Lin, Y. Y., M. Risk, S. M. Ray, D. VAN ENGEN, J. GoLik, J. C. JAMES, AND K. NAKANISHI. 1981. Isola- tion and structure of brevetoxins B from the “‘red tide’ dinoflagellate Ptychodiscus brevis (Gymnodinium breve). J. Am. Chem. Soc. 103:6773-6775. Martin, D. F. AND W. H. Tarr. 1998. Management of the Florida red tide—revisited. Florida Scient. 61: 10-16. ROUNSEFELL, G. A. AND W. R. NELSON. 1966. Red-Tide Research Summarized to 1964 Including an Annotated Bibliography. Spec. Sci. Rpt-Fish. No 535, Bureau of Commercial Fisheries, Fish and Wildlife Service, U. S. Sept of Interior, Washington D. C. Simon, J. L. AnD D. M. Dauer. 1972. A quantitative evaluation of red tide induced mass mortalities of benthic invertebrates in Tampa Bay, Florida. Environ. Letters 3:229-234. STEIDINGER, K. A. 1983. A re-evaluation of toxic dinoflagellate biology and ecology. Prog. Phytocol. Res. 2:147-188. AND R. M. INGLE. 1972. Observations of the 1972 summer red tide in Tampa Bay, Florida. Environ. Letters 3:271-278. AND H. L. MELTON Penta. 1999. Harmful microalgae and associated public health risks in the Gulf 2 FLORIDA SCIENTIST [VOL. 66 of Mexico. U.S. E.P.A. Gulf of Mexico, U.S. E.P.A. Grant # MX004729-95-0. Environmental Protection Agency, Washington D. C. STREETER, V. L. 1969. Pipe flow, McGraw-Hill Ency. Sci. Techn. 10:239-241. AND E. B. Wy ig. 1985. Fluid Mechanics. 8" ed. McGraw-Hill Book Co., Inc. New York, NY. Tart, W. H. anp D. F. Martin. 1986. The potential for managing a Florida red tide. J. Environ. Sci. Health A21;107—127. Florida Scient. 66(2): 109-112. 2003 Accepted: September 17, 2002 Biological Sciences TEMPORAL DIVERSITY AND ABUNDANCE OF DRIFT MACROPHYTES AND ASSOCIATED ORGANISMS IN MOSQUITO LAGOON, VOLUSIA COUNTY, FLORIDA MaARIE-JOSEE ABGRALL AND LINDA J. Watters! Department of Biology, University of Central Florida, Orlando, FL 32816 Asstract: In terms of biomass, drift algal communities are often the dominant organisms in estuaries. On the east coast of central Florida, drift communities have been studied primarily in the southern reaches of the Indian River Lagoon system. To determine the abundance and diversity of floating drift macrophytes and associated fauna in Mosquito Lagoon, the northernmost region of the Indian River Lagoon, monthly observations were run for a 2-year period, beginning in April 1998. For each 24-hr sampling period, all drift was collected every 4 hr, brought into the laboratory, sorted by species, and weighed. Environmental data (salinity, wind speed, water motion, water and air temperatures) was also recorded every 4 hr. During the two-year survey, 26 species of drift macrophytes were collected in Mosquito Lagoon. Red algae of the genus Gracilaria and the seagrass Halodule wrightii were found in the greatest abundances, representing 51.7% and 23.7%, respectively, of all macrophyte biomass collected. Invertebrates and fishes (e.g. the code goby Gobiosoma robustum) were, at times, found in high densities attached or closely associated with these topographically complex, drift communities. No correlations between macrophyte abundance and wind speed or flow rate were found. Additionally, no consistent temporal patterns of macrophyte abundances were observed. Key Words: drift algae, Gracilaria, Halodule wrightii, Indian River Lagoon, Canaveral National Seashore MANY species of macroalgae incorporate drifting into their life-histories as mechanisms for dispersal and survival in areas where predators or storm events are common (e.g. Norton and Mathieson, 1983; Bushing, 1994). For some species of algae, dislodged fragments can rapidly attach to benthic organisms or to sand (e.g. Walters and Smith, 1994; Smith and Walters, 1999; Walters and Beach, 2000). Dis- lodged fragments of other species of macroalgae never reattach, but can survive long periods of time floating or tumbling over the benthos (Kain and Norton, 1990; Astill and Lavery, 2001). Clumps of drift algae may remain viable for months, de- composing only when physical conditions change or the clumps are washed above the high tide line (Highsmith, 1985; Virnstein and Carbonara, 1985). Many mobile and sessile invertebrates and a few fish species (1.e. the code goby Gobiosoma robustum and the gulf pipefish Syngnathus scovelli) are frequently found in high densities attached or closely associated with these topographically complex, drift algal communities (e.g. Kulczycki et al., 1981; Lewis, 1987; ' Corresponding Author: ljwalter@pegasus.cc.ucf.edu 113 114 FLORIDA SCIENTIST [VOL. 66 Virnstein and Howard, 1987; Ingolfsson and Olaffson, 1997; Knowles and Bell, 1998; Brooks and Bell, 2001). For example, Norkko and co-workers (2000) counted over 1100 mobile invertebrates/g algal dry weight on mixed species clumps of drift algae in the Baltic Sea. Kulczycki and co-workers (1981) counted 6300 amphipods in a 600 g sample of drift algae in a Florida estuary. Numerous species of anemones, molluscs, amphipods, echinoderms, sponges and bryozoans have also been observed moving offshore in the California current system on kelp blades (Bushing, 1994). For sessile organisms, the colonization of drift macroalgae occurs either by larval recruitment onto drift macrophytes or settlement on attached plants that sub- sequently break off and enter the drift (Jackson, 1986). Abgrall (2002) looked at the importance of the drift alga Gracilaria on the dispersal of the sessile bryozoan Bugula neritina and found that Bugula larvae settled in large numbers on drift individuals, but avoided attached plants of the same species. Both positive and negative interactions have been documented between drift macrophytes and associated fauna (e.g. Kingsford, 1992). Drift algal mats can act as floating rafts or marine tumbleweeds that aid in the dispersal of fishes and invertebrates (Highsmith, 1985; Virnstein and Howard, 1987; Holmquist, 1994; Helmuth et al., 1994; Kingsford, 1995; Brooks and Bell, 2001; Abgrall, 2002). Dispersal potentials over 1.0 km/d have been estimated for Tampa Bay, FL (Brooks and Bell, 2001). Predation on invertebrates by fish is frequently significantly reduced in drift algae clumps due to high habitat complexity and increased number of refuges (Kulczycki et al., 1981; Aarnio and Mattila, 2000). Additionally, some invertebrates can forage directly on drift macrophyte hosts or it’s epiphytes (Zimmerman et al., 1979). Negative faunal impacts of individuals in contact or close proximity to drift algal clumps include: 1) losses associated with being in drift clumps that become stranded by ebbing tides (Highsmith, 1985; Virnstein and Carbonara, 1985), and 2) mortality due to low levels of dissolved oxygen. For example, in the northern Baltic Sea, researchers have found hypoxic conditions and reduced biodiversity in soft-bottom communities under ephemeral mats of drift algae (Norkko, 1998; Norkko et al., 2000). Likewise, Astill and Lavery (2001) found hypoxic conditions and increased ammonia levels under drift algae within 24 hr of the arrival of the macroalgal mats in the Swan-Canning Estuary in western Australia. Alternatively, Sundbaeck and co-workers (1996) did not find any adverse effects of the green alga Enteromorpha covering benthic microbial mats. In the Indian River Lagoon (IRL), on the east coast of central Florida, algal biomass exceeds seagrass biomass in many places, especially during the winter and spring months (Thompson, 1978; Benz et al., 1979; Virnstein and Carbonara, 1985). Epiphytic, free-standing attached, and drift forms of many algal species can all be found in these waters (Walters et al., 2001). In particular, Virnstein and Carbonara (1985) found that in the southern reaches of the IRL near Fort Pierce, FL, drift algae, primarily Gracilaria spp., was temporally and spatially very abundant, and in some sheltered, shallow water locations in spring months, drift algae biomass exceeded 15,000 g/dry wgt/m*. The goal of the present study is to better understand the diversity of flora and fauna that moves in the surface drift in Mosquito Lagoon, the northernmost part of the IRL. This is the first time temporal diversity of drift has No. 2 2003] ABGRALL AND WALTERS—DRIFT MACROPHYTES i Fic. 1. Map of the east coast of central Florida and the Indian River Lagoon system (left), and map of the location of Fellers House Field Station in Canaveral National Seashore (right). been quantified in these waters. For this study, monthly 24-hr observations were made for a 2-year period, beginning in April 1998. MetTHops—AIll drift collections were made in northern Mosquito Lagoon, immediately seaward of the University of Central Florida Field Station dock (28°54'N; 80°49'W) (Fig. 1). This site is directly south of Eldora State House in Canaveral National Seashore. At its southern end, Mosquito Lagoon is connected to the Indian River via Haulover Canal; at its northern end, it is connected to the Atlantic Ocean through Ponce de Leon Inlet (Fig. 1). At this site, the average depth is 1.5 m. Throughout the year, salinity ranges from 30-46 ppt, mean water temperature ranges from 17—28 degrees C, and 122—142 cm of rain falls on an annual basis (Walters et al., 2001, unpublished data). Waters in Mosquito Lagoon are moved by both the wind and tides; the former dominates and it is classified as a wind-driven system (Walters et al., 2001). Twenty-four hour surveys were run once a month for two years, beginning in April 1998. On each sampling date, all floating macrophytes and associated organisms were collected from our nets every four hours. Twelve collectors were created from 0.1 cm fiberglass screen mesh that was sewn together with 100 Ib. test fishing line to create 84 cm long X 33 cm diameter nets (Fig. 2). Groups of three collectors were attached to two 160 cm PVC pipes (diameter: 1.9 cm) with cable ties (Fig. 2). The first collector was attached 50 cm from the end of the PVC pipe and the remaining two collectors were then spaced 30 cm apart. To keep the opening of each net circular, the open end of each collector was reinforced with 116 FLORIDA SCIENTIST [VOL. 66 cenererer ce recorder 3 collectors Fic. 2. Design of drift macrophyte collectors. 20 X 33 cm wide strips of rigid plastic mesh (Vexar: 0.6 cm mesh openings) covered by fiberglass screen mesh. Two BL-3 styrofoam buoys helped maintain the opening of the nets near the surface of the water (Fig. 2). Four sets of algal collectors were arranged in a square (Fig. 2). Six nets were placed parallel to the shore with their open ends facing north and south and the other six were placed perpendicular to the shore with their openings facing east and west (Fig. 2). Each PVC pipe of the set had its ends loosely attached to two 160-cm PVC poles (diameter: 2.5 cm) submerged 45 cm perpendicular to the substrate, allowing the surface algal collectors to move up and down with the tides. These PVC poles were placed at a distance of 180 cm seaward of the dock and 165 cm from each other. They remained in the water for the two years of this study. Accumulated drift organisms were removed from the nets every 4 hours during each 24-hr sampling period. All organisms were sorted to species and identified. Counts were made for invertebrates, seeds and fishes for each 4-hr period. After sorting collected macrophytes (macroalgae, seagrasses), all were blotted dry, and weighed. Wet weights were made by first spinning off excess water with a salad spinner for 45 s and then weighing the algae or seagrass biomass on an electronic, top-loading balance (Ohaus Scout II, Model SC2020). The number of attached, sessile organisms on each piece of drift was also recorded and removed before the algal biomass was weighed. Algal identifications were made using two reference collections made for Mosquito Lagoon, one from winter 1998 and one from summer 1998. Dr. Clinton Dawes, University of South Florida, confirmed the identification of all specimens from these collections. Immediately before removing accumulated drift every four hours, environmental data were collected at the study site. The maximum flow rate in water adjacent to the collectors was determined using four pre-calibrated maximum velocity flow recorders (Bell and Denny, 1994). One device was placed on each vertical PVC pole of the drift collectors (Fig. 2). Salinity was measured using a refractometer, water and air temperatures were measured using a mercury-filled glass thermometer, and the wind speed was recorded using a Kestrel 2000 wind gauge. Spearman’s correlation coefficient tests (a= 0.05) were used to determine if there was a significant linear relationship between the abundance of collected drift macro- phytes and the wind speed and between drift abundance and maximum flow rate on each sampling date. ResuLts—During the two-year field survey, 26 species of drift macrophytes were collected in our nets in Mosquito Lagoon. Red algae of the genus Gracilaria and the seagrass Halodule wrightii were found in the greatest abundances, representing 51.7% and 23.7% respectively, of all macrophyte biomass collected No. 2 2003] ABGRALL AND WALTERS—DRIFT MACROPHYTES a7 Spyridia filamentosa ) = Enteromorpha spp. | 1.5% 1.5% Dasya baillouviané Cladophora sp. 12.5% Gracilaria spp. 51.7% 23.7% Fic. 3. Overall percentage of drift macrophytes found in nets during monthly 24-hour collections for a 2-year period, beginning April 1998. The species Gracilaria armata, G. tikvahiae, G. cylindrica, G. blodgettii, G. compressa, and G. verrucosa are grouped under the genus Gracilaria. Enteromorpha compressa, E. intestinalis, and E. prolifera are grouped under the genus Enteromorpha. Other = Acanthophora spicifera (0.7%), Hypnea spinella (0.5%), Agardhiella subulata (0.2%) and Chondria littoralis (0.1%). (Fig. 3). Among the various species of Gracilaria collected, G. armata and G. tikvahiae were most commonly found. Various size fragments of G. verrucosa, G. compressa and G. blodgettii were also found on some sampling dates. Represent- ing 12.5% of all macrophytes collected, the green alga Cladophora sp. was fre- quently found entangled with Gracilaria. The red alga Dasya baillouviana was not observed as drift or attached in Mosquito Lagoon in 1998. However, in 1999 and 2000, large clumps of this feathery alga were collected, representing 7.7% of the total biomass (Fig. 3). Among the species of Enteromorpha collected (1.5% total biomass), E. intestinalis was most frequently found. Enteromorpha compressa and E. prolifera were collected on a few occasions. Spyridia filamentosa was found primarily as an epiphyte on other algae and accounted for 1.4% of the total biomass (Fig. 3). The red alga Acanthophora spicifera, Hypnea spinella, Agardhiella subulata and Chondria littoralis were rarely collected and combined represented 1.5% of the total biomass (Fig. 3). No consistent temporal patterns were observed over the course of the 2-year study. Most Gracilaria biomass was recorded during April 1998 (Fig. 4). At this time, a mean amount of 185.1 g was collected every 4 hours (Fig. 4). Smaller peaks of Gracilaria abundance were found in August 1998 (9.6 g/ 4 hr) and February 1999 118 FLORIDA SCIENTIST [VOL. 66 Grams per 4 hr Apr-98 Jun-98 Aug-98 Oct-98 Dec-98 Feb-99 Apr-99 Jun-99 Aug-99 Oct-99 Dec-99 Feb-00 Apr-00 —@— Gracilaria spp. Fic. 4. Mean abundance of drift macrophytes (+S.E.) found in nets during monthly 24-hr collections for a 2-year period. Gracilaria spp. includes G. armata, G. blodgettii, G. compressa, G. cylindrica, G. tikvahiae (two morphs), and G. verrucosa. (3.1 g/ 4 hr) (Fig. 4). With the exception of December 1999, Halodule wrightii was found every month, with greatest abundances during July 1999 (59.4 g/ 4 hr) and August 1999 (10.1 g/ 4 hr) (Fig. 5). The macroalga Cladophora sp. was not ob- served in the nets in 1998, but was found in 1999 and 2000 (Fig. 5). Cladophora sp. was generally found during the winter months, especially February 2000 (40.5 g/ 4 hr) (Fig. 5). The abundance of Acanthophora spicifera, Enteromorpha spp., and Spyridia filamentosa also varied temporally (Fig. 6). No consistent temporal patterns were observed for either flow rate or wind speed during the monthly 24-hr collections (Fig. 7). Despite high wind speeds recorded in April 1998 (7.1 + 1.87 m/s), June 1998 (8.9 = 1.0 m/s), November 1999 (13.0 + 1.0 m/s), and February 2000 (6.7 + 2.6 m/s), there was no significant linear correlation between overall abundance of drift biomass and wind speed (Spearman’s correlation coefficient test: p value = 0.306). Thus, an increase in wind speed did not predict the abundance of macrophyte biomass during the monthly survey or the subsequent month. Likewise, the months with highest maximum flow rates did not correlate with the months with largest macrophyte biomass (Spearman’s correlation coefficient test: p value = 0.435). Thunderstorms occurred during collections in August 1998, July 1999, August 1999 and September 1999. These storms (maximum duration: 2 hours) potentially impacted the abundance of drift macrophytes during these sampling periods. However, neither strong winds nor increased flow rates were recorded during these collections. Invertebrates and fishes were found in nets during the 24-hr collections and as with the drift macrophytes, faunal abundances varied temporally and no consistent patterns were observed (Tables 1-3). Sessile invertebrates were infrequently collected attached to drift (Table 1). The bryozoan Scrupocellaria bertholleti was No. 2 2003] ABGRALL AND WALTERS—DRIFT MACROPHYTES 119 Macrophytes (g) per 4 hr ies) ie.2) (oe) io, ) ic.) a nN iow Oo a loa} S S a ON Oo io) Oo Oo On Oo ion fon) Oo i=) (S im i= on = Q we) a S on $ 9 2 < 5 z fo) A ts < 5 < ) A x < —@— Halodule wrightii —& Cladophora sp. —t— Dasya baillouviana Fic. 5. Mean abundance of drift macrophytes (+S.E.) found in nets during monthly 24-hr collections for a 2-year period. occasionally found attached to Gracilaria sp. Other sessile invertebrates collected in the drift included the feather duster worm Sabella melanostigma (primarily attached to Gracilaria sp.), Spirobis sp. attached to the red alga Hypnea, and the stoloni- ferous ascidian Perophora viridis attached to Gracilaria and Hypnea fragments (Table 1). Unattached invertebrates either moving on the surface alone or associated, but not attached to drift plants, included members of a wide range of taxa. Huge numbers of the comb jelly Mnemiopsis mccradyi were found in October and November 1998, April, May, July, and October 1999, and March and April 2000 (Table 1). A few snails (Littorina irrorata) and one sea slug (Doriopsilla pharpa) were collected crawling on fragments of Gracilaria sp. Many crustaceans, includ- ing isopods, amphipods, shrimp and crabs were collected in nets with drift algae (Table 2). The number of isopods (valiferans, anthurideans, and flabelliferans), amphi- pods (gammarids and caprellids), and the shrimp Palaemonetes sp. were extremely variable over time (Table 2). December 1999 was the only sampling date when all three small crustacean taxa were found in large quantities (Table 2). Porcelain crabs (Megalobrachium soriatum), blue crabs (Callinectes sapidus), and hermit crabs (Clibanarius vittatus) of various sizes were also collected in nets and their numbers varied over time (Table 2). Various species of fish and fish larvae were observed in nets during the 24-hr collections (Table 3). Total numbers of these fish varied temporally (Table 3). More than 50% of the code gobies (Gobiosoma robustum) were collected during April and August 1998, two dates when large amounts of drift algae were also collec- ted (Fig. 3). The spotted sea trout Cynoscion nebulosus, the pinfish Lagodon rhomboides, the pigfish Orthopristis chrysoptera, and the seahorse Hippocampus sp. were infrequently found in nets (Table 3). 120 FLORIDA SCIENTIST [VOL. 66 Macrophytes (g) per 4 hr (oo N° .2 © ,© >. © EL °° EE” © EEL °° IE, © EEL ©, © EE © EEE © EEE © EEE © 2 EE © DEE © DE © 2 SRFRRRRFRKRFRFRFRKRRRAERRES ES es A S&S Se © Ga Hh fr & S&S Oo F&F F&F AD SF Be OE & So. Pao) ce oe aaeas 5B s op YP 6 FS B&B woOS a ke SB FB BSB OD YF 6 DS & DO a. 2g F228 07 A525 f¢S FF ZR OF 6 See —®— Acanthophora spicifera —& Enteromorpha spp. —t— Spyridia filamentosa _| Fic. 6. Mean abundance of drift macrophytes (+S.E.) found in nets during monthly 24-hr collections for a 2-year period. Enteromorpha spp. includes E. compressa, E. intestinalis, and E. prolifera. A few fragments (<5 individuals total) of coastal, upland angiosperms, including the glasswort Salicornia perennis and the sea purselane Sesuvium portulacastrum, were found in September and October 1999. This coincides with stormy weather on these sampling dates. Several seeds of the black mangrove Avicennia germinans were also collected, mostly in November 1999 (Table 1). Discussion—In terms of biomass, drift algal communities are often the dominant communities in sandy bays and estuaries (e.g. Eiseman and Benz, 1975; Norton and Mathieson, 1983, Virnstein and Carbonara, 1985). This is especially true in the Indian River Lagoon system, where hard substratum for attachment of algae is extremely limited (Virnstein and Carbonara, 1985; Walters et al., 2001). In these waters, attached algae were only found on oyster shells, mangrove roots and man- made substrates, including jetties, pilings, floats and seawalls (Eiseman and Benz, 1975; pers. obs.). While most macroalgae begin their lives as attached individuals, macroalgae do not need to be attached to survive (Kain and Norton, 1990). Based on observations made by Eiseman and Benz (1975), almost any species of macroalgae observed in the Indian River Lagoon may be found in the drift community at some time. They found 31 species of drift macroalgae. Twenty-six species of drift macrophytes were observed in the present study and drift clumps were frequently composed of multiple species. Similar to findings in the southern reaches of the IRL (Virnstein and Carbonara, 1985), we found Gracilaria sp. dominated the drift community in the northern IRL. However, our values do not come close to the biomass measures they report: 15,000 g/ dry weight/m7 (Virnstein and Carbonara, 1985). Although the collection locations were similar in depth, our site was over 100 km further north and significantly cooler No. 2 2003] ABGRALL AND WALTERS—DRIFT MACROPHYTES 121 18 16 16 + 2 \ r | f = eT +12 2 a. | B waa 7 S 2 4 slr ss 3 10 ERO pe 2 ks L z J 7 8 ee ee 8 + 2 Fe + 6 Bue + E = zt I4 7 4+ t > + 2 Pheer Ss oO} wae HH tt ++ Ht OO i.2) [o-2) [°.2) [oe] [o/2) fon) a [oy Oo (oy lop (=) S Se SR RR EO DS OS = | el) 3 i>) a) (S| on rR >) He) i ewe Se ee a Ola ee —@— Flow rate (cm/s) —k—wind (m/s) | Fic. 7. Mean maximum flow rate (+S.E.) and wind speed (+S.E.) recorded during monthly 24-hr collections during the 2-yr study. Wind speed data was not collected in March 1999 due to equipment failure. in winter months (Walters et al., 2001). Additionally, we only collected surface drift, while Virnstein and Carbonara (1985) collected drift throughout the water column. The abundance of the green alga Cladophora sp. was much greater in the present study than in previous collections (Eiseman and Benz, 1975; Fig. 3). Although present in the southern IRL, the red algae Jania adherens and Laurencia sp. and the brown algae Rosenvingea intricata and Dictyota dichotoma were not collected in Mosquito Lagoon (Eiseman and Benz, 1975; Virnstein and Carbonara, 1985). Representing 7.7% of the total biomass collected, the red alga Dasya baillouviana appeared to be an important new addition to the drift algal community in the Indian River Lagoon system (Fig. 3). Only a few epiphytic individuals of this genus were previously recorded (Benz et al., 1979). Virnstein and Carbonara (1985) found that the drift alga abundance varied significantly over time. They also found most high-density carpets of drift algae (thickness: 15—30 cm) between mid-December and early May, and by late July, drift algae near Fort Pierce, FL was sparse and mostly decomposed (Virnstein and Carbonara, 1985). They suggested that, in the spring, drift algae may be trapped by the fast-growing seagrass beds, forming large, stationary accumulations (Virnstein and Carbonara, 1985). Reduced light penetration, higher temperatures, increased pre- cipitation, greater freshwater runoff, and competition with seagrasses for nutrients may have also been responsible for the decline of drift algae during the summer months (Benz et al., 1979; Virnstein and Carbonara, 1985). Similar temporal dif- ferences were found in our collections (Figs. 4—6). Collection dates with high abundances of drift algae were also dates with high abundances of both sessile and mobile invertebrates and fishes (Figs. 4-6, Tables 1-3). Although we can not eliminate the potential that some mobile species, such as the blue crab Callinectes sapidus, were collected because they were attracted to the [VOL. 66 FLORIDA SCIENTIST 122 val li 608< 6€ EI [eo L, 0 0 OS< 0 0 00-Tudy 0 0 0s< 0 0 00-Yore| 0 0 OI 0 0 00-Arenig9,j I 0 6 0 0 0o-Arenue 0 0 0 0 0 66-oquisceq, El 0 I 0 0 66-OqUISAON 0 0 007< 0 0 66-10q40190 0 0 0 0 0 66-Jequiaydag 0 0 Gil 0 0 66-3snsny 0 0 os< 0 0 66-Aqne 0 0 € 0 0 66-ounL 0 0 0Os< 0 0 66-ACI 0 0 0s< 0 0 66-Thdy 0 0 Z 0 0 66-Alenigoy 0 0 So 0 0 66-Arenues 0 0 ¢ 0 0 86-Joquisceq 0 0 os< 0 0 86-JOqUIDAON 0 I 007< 0 0 86-19q0190 0 Z 07 0 0 86-Joquiajdag 0 v 8 Ce 0 S6-snsny 0 0 8 0 v 86-Aqne 0 0 0 0 0 86-ouns 0 0 0 0 0 86-AP 0 0 9 LI 6 86-Tudy Spoos “ON S[TENPIAIpUl “ON SJENPIAIPUI "ON S[TENPIAIPUI “ON SOTUO[OD “ON 21eq (QAOIZSUPU Ye) ({reus podonse3) (Ayal quiod) (ajeayoAyod sJ0}snp-J9yed}) (ueOZOAIQ) 172]/0Y4142q SUuDUILAIS DIDAOAAL DUIAO] JIT 1dppszIU Sisdommaupy DUBIJSOUDJAU DIJIGVS D1IAD]JIIOdNAIS DIUUIIIA “pojuasaid are sye}0} IY-pZ ‘Peplooal aI9M STeNPIAIPUI G< YOIYM UI satoads |[e 10,J “suOTOaT[OO IY-pz ATYUOW SuLINp sjou UI puNoJ suULIodsoIsuR puUP SoJeIGOVIOAUI JO JOqUINN] “| ATAV], 123 ABGRALL AND WALTERS—DRIFT MACROPHYTES No. 2 2003] 961 [BIOL I] 6 8 0 0 0 I 0 0 + 00-Tdy 0 0 0 TA 0 ++ ++ OO-YoreA] 0 G 0 I + 4 ++ 00-Areniqe,j 0 0 0 CI 0) ++ ++ QO-Arenue 0 0 0 I eee ++ eee 66-Joquisceq 0 0 0 0 ++ 0 0 66-JOQUIDAON 0 0 0 0 0 0 0 66-10q0190 0 0 0 0 + 0 0 66-Joquiaydag 0 0 0 6 0 0 + 66-snsny 0 0 0 € ++ 0 0 66-Aqnf © I 0 ¢ ++ 0 0 66-ounL 0 0 0 I + 0 0 66- API 0 0 Z ik 0 eee 0 66-udy 0 0 i I 0 0 0 66-Areniqa{ 0 0 I v 0 ++ 0 66-Arenue ys 0 I 0 € ++ + 0 86-oquiacaq 0 I 0 iG aah 0 0 86-OqUIDAON (6 I 0 Z sid 0 = 86-19q0190 Y (C € Life ++ 0 ae 96-oquiajdas I I 0 OL 0 0 0 So-snsny 0 0 0 € 0 0 + 86-Aqne 0 0 0 0 0 0 0 g6-oune 0 0 0 0 0 0 0 86-API 0 0 0 SI 0 ++ 4 86-Tudy (qeio JIULIOY) (qeio onyq) (qeio ule[aoiod) (duiiys provuad) (duiys ssvi3) spodiydury spodos] aed SNID]IIA snpidps Wnj]DIAOS ‘ds SHIDUId ‘ds SIJUOWMIDIDd SHLADUDGI).) SIJIOUTID WNIYIDAGO]DBI ‘Ioy1930) podnoss ore ovpryjaideD pue vopuewluey siaploqgns ay} Jo SJOqUIOU pur so1dads 0) poynusp! jou o19M spodiydury “1oyje30) podnoss aie vsopIT[oquiy puv ‘voplNy UY ‘VIOJIATVA SIOPAOgnNS oy} JO saquoW pur soldads 0} payNuept JOU 319M spodosy] ‘so1dads JoYIO ][e JO} posn o1oM sJUNOD ‘WUepuNqe = ++ puR ‘May = + ‘oUOU = (J SB popsOSaI pur (‘ds sajauotanjpg Cuunys sseis oy) ‘spodrydure ‘spodos!) suedovjsnio Jd[[BUIS OJ PopIOSI SEM S[eNPIAIPUL JO DOUdSqe 10 DOUdSdIg “SUOTIDET[OO IY-pZ ATYJUOW SuLINp sjou UT PUNO] suBdOvISNID *7 ATAV], [VOL. 66 FLORIDA SCIENTIST 124 ooNnmooonrooco7ccooceooonoococo © oo =) VAIL] USL oo oc ooo © @ © © © © © ©. oS] .S.ete4on— oO (as1oyeas) ‘ds sndupooddiyy Sooqoom ooqooclcmU6UOhUMN OF Oh. 6S 6S. ho Lh SSeS = = So (ysyodid) ‘ds snyjpusud¢g OSonmooqoqooqqocqcucCcmmw6WlCc CO Cc Oh h6O ULhDS L6S LOLS FS Ser o (ysysid) psa]dosaays S1JS14d0YJAQ GSaoor7aqoqooqcocluUccdlhclhlUhcOlUwO Uh CO LO LOLS SS log) oS (ysyurd) saploquioy UOpOBVT OS oqo oqornodoqoqooc od © © © © © Oo 2 Ce Sogo n (ino vas panods) snsojnqau uolgsOucD N log) Ooo roqoqoqocqo ct © © = © © Oo Ojo [qn S Ol (Aqo3 apod) WIN]SNgod DULOSO1GOH) [eIOL 00-Tudy OO0-YoeI 00-Areniqe,f Qo-Arenue ¢ 66-Joquia.00q, 66-JOqUISAON 66-4990190 66-Zoquiaidas 66-}sn3snVy 66-A[nf 66-9uns 66-ARI 66-Tudy 66-Alenigo] 66-Arenue er 96-oquisceq 86-1OQUIDAON 86-49q0190, 96-Joquiajdag Q6-Isn3sny 86-AIng Q6-ounr 86- AP 86-dy aeq “SUOTIDAT[OO IY-pZ A]TYJUOW SuLINp s}ou UT puNo}J soysy Jo JOqUINNY “¢€ ATAV] No. 2 2003] ABGRALL AND WALTERS—DRIFT MACROPHYTES 25 structure of the collectors, much of the high diversity of fauna is likely due to the fact that the drift macrophytes provided refuge from predators (e.g. Lenanton et al., 1982; Norkko et al., 2000). Protection may have been both physical (i.e. topographical complexity) and via secondary metabolites associated with the macrophytes (e.g. Walters and Wethey, 1991). Although some marine algae may produce chemicals that are toxic to settling larvae (Walters et al., 1996), this anti- fouling protection may be lost when the alga enters the drift (Abgrall, 2002). Abgrall (2002) found that larvae of the bryozoan Bugula neritina avoided attached Gracilaria armata, but settled in large numbers on drift forms of the same species. Rafting on drift macrophytes can significantly impact the dispersal potential for some animals. For example, Abgrall (2002) examined the impact of rafting on Gracilaria armata on the dispersal potential for the arborescent sessile bryozoan Bugula neritina. Larvae of Bugula are approximately 167 microns, ciliated spheres that move passively with the current (Walters and Wethey, 1996). The larvae are also non-feeding and have approximately 24 hours before stored food reserves are depleted (Woollacott and Zimmer, 1971). Near the study site in Mosquito Lagoon, water movement averaged 5 cm/s (pers. obs.). Thus, larvae of B. neritina could potentially disperse 0.43 km from the source in 24 hr. If larvae settle on drift macrophytes, over 15-d period, they could potentially disperse 7.3, 12.9 or 87.5 km at wind speeds of 0.4 m/s, 3.5 m/s, and 6.7 m/s, respectively (Abgrall, 2002). Thus, rafting would significantly increase dispersal of this bryozoan. Likewise, Brooks and Bell (2001) found that drift clumps of Hypnea cervicornis acted as mobile corridors across a seagrass bed landscape for amphipods, enabling them to disperse over 1.1 km/d. In summary, 26 species of drift macrophytes were collected in the surface drift in Mosquito Lagoon during the two-year survey. Although no consistent temporal patterns were evident, Gracilaria spp. and the seagrass Halodule wrightii dominated the drift biomass. Invertebrates and fish were, at times, found in high densities attached to or closely associated with these topographically complex, drift communities. No correlations were found between macrophyte abundance and wind speed or macrophyte abundance and maximum flow rate. ACKNOWLEDGMENTS—We thank the University of Central Florida, the National Park Service, the Museum of Natural History Lerner-Gray Fund for Marine Research, and the American Women’s Fishing Association for supporting this research. Canaveral National Seashore Superintendent R. Newkirk and Resource Management Specialist J. Stiner provided access to this beautiful and unique habitat. Field assistants we wish to acknowledge include F. Croteau, K. Holloway-Adkins, D. Byron, E. Flores, P. Sacks, J. Sacks, B. Macllrath, A. Roman, K. Johnson, and M. Love. Additionally, we especially grateful to Dr. C. Dawes for algal identifications, Drs. K. Beach, I. J. Stout, W. Taylor and P. Sacks for reading drafts of this manuscript, Dr. F. Snelson for fish identifications, and to Dr. L. Hoffman for statistical advice. LITERATURE CITED AARNIO, K. AND J. Mattia. 2000. Predation by juvenile Platichthys flesus (L.) on shelled prey species in a bare sand and a drift algae habitat. Hydrobiologia 440:347-355. ABGRALL, M.-J. 2002. Settlement preferences, recruitment, and dispersal potential of the bryozoan Bugula neritina on drift macroalgae in Mosquito Lagoon, Volusia County, Florida. M.S. Thesis, University of Central Florida, Orlando, FL. 79 pp. 126 FLORIDA SCIENTIST [VOL. 66 ASTILL, H. AND P. S. LAvery. 2001. The dynamics of unattached benthic macroalgal accumulations in the Swan-Canning Estuary. Hydrol. Process. 15:2387—2399. BELL, E. C. AND M. W. Denny. 1994. Quantifying “‘wave exposure’’: a simple device for recording maxi- mum flow velocity and results of its use at several field sites. J. Exp. Mar. Biol. Ecol. 181: 9-29. Benz, M. C., N. J. EISEMAN, AND E. E. GALLAHER. 1979. Seasonal occurrence and variation in standing crop of a drift algal community in the Indian River, Florida. Bot. Mar. 22:413-420. Brooks, R. A. AND S. S. BELL. 2001. Mobile corridors in marine landscapes: enhancement of faunal exchange at seagrass/sand ecotones. J. Exp. Mar. Biol. Ecol. 264:67-84. BusHING, W. W. 1994. Biogeographic and ecological implications of kelp rafting as a dispersal vector for marine invertebrates.The Fourth California Islands Symposium, pp. 103-110. EIsEMAN, N. J. AND M. C. BENZ. 1975. Studies of the benthic plants of the Indian River region. Pp. 89— 103. In: Indian River Coastal Zone Study, Annual Report 1974-1975, Vol. 1, Harbor Branch Foundation, Inc., Fort Pierce, FL. HELMUTH, B. S., R. R. VEIT, AND R. HOLBERTON. 1994. 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Florida Scient. 66(2): 113-127. 2003 Accepted: September 24, 2002 Biological Sciences WILDLIFE MORTALITY ON U.S. HIGHWAY 441 ACROSS PAYNES PRAIRIE, ALACHUA COUNTY, FLORIDA (1,2) (2) Lora L. SMITH AND C. KENNETH Dopp, JR. “Joseph W. Jones Ecological Research Center, Route 2 Box 2324, Newton, Georgia 39870 U.S. Geological Survey, Florida Caribbean Science Center, 7929 NW 7\st Street, Gainesville, Florida 32653 ABSTRACT: Wildlife mortality was documented for one year on a 3.2 km section of U.S. Highway 441 in Alachua County, Florida, prior to construction of a wildlife barrier/underpass system. A total of 1,821 vertebrates, representing 62 species, were recorded dead on the road during 105 sampling days; counts were conducted weekly for 52 consecutive weeks. The most common species killed were green treefrog (Hyla cinerea; n = 296), southern leopard frog (Rana sphenocephala; 230), Florida water snake (Nerodia fasciata pictiventris; 1/94), pig frog (Rana grylio; 145), and green water snake (Nerodia floridana; 1/9). U.S. Highway 441 at Paynes Prairie appears to have one of the highest levels of snake road mortality ever reported; dead snakes were observed at a rate of 1.854 individuals per km surveyed (336 km surveyed/623 snakes killed). Key Words: Paynes Prairie, Reptiles, Amphibians, Snakes, Roads, Mortality THERE have been numerous reports of significant mortality of amphibians and reptiles on U.S. Highway 441 across Paynes Prairie in Alachua County, Florida [Beck, 1938; Carr, 1940; 1974; Hellman and Telford, 1956; Kauffeld, 1957; Franz and Scudder, 1977; unpubl. data Florida Department of Transportation (FDEP), Gainesville, FL]. Anecdotal accounts suggested that there was a declining trend in snake populations in the vicinity of the road, most likely related to long term road mortality (Carr, 1974). In addition to mortality of individual animals, the roadway was thought to act as a nearly impenetrable barrier to snake movements (Franz and Scudder, 1977). Although snakes and frogs comprised the majority of kills on U.S. 441, more than 60 species of vertebrates have been reported killed on this 3.2-km stretch of highway (unpubl. data FDEP, Gainesville, FL). In January 2000, the Florida Department of Transportation (FDOT) began construction of a barrier wall and underpass system (ecopassage) to reduce wildlife mortality by physically preventing access to the roadway and by directing snakes and other vertebrates through culverts beneath the road. Prior to construction of the ecopassage system, we conducted a year-long survey to determine pre-construction mortality levels. These data, and those of a post-construction survey, will be used to evaluate the effectiveness of the ecopassage system in decreasing or preventing vertebrate mortality. A concurrent monitoring study at existing and new culverts will determine whether snakes and other vertebrates use culverts to pass under the roadway. Results of the pre-construction road mortality study are presented here. 128 No. 2 2003] SMITH AND DODD—PAYNES PRAIRIE ROADKILL 129 Paynes Prairie is a large highland freshwater marsh along the central Florida Ridge in Alachua County. Highland marshes are shallow wetlands characterized by unstable drainage patterns (Kushlan, 1980). Depending on rainfall and drainage, Paynes Prairie may be a dry prairie, marsh, or shallow lake. Water on the prairie flows east where it drains into Alachua Sink. The prairie basin encompasses an area nearly 5,000 ha in size and was designated as a State preserve in 1970. The prairie is transected by two major roads, Interstate 75 (I-75) and U.S. Highway 441 (U.S. 441). U.S. 441 was built in 1923 and was expanded from two to four lanes in 1957. Fill for the roadway was taken from the adjacent marsh, which created shallow canals that parallel the road. The highway is ca. 50 m wide (including a grassy clear zone, paved lanes, and grassy median) and it traverses 1.8 km of the prairie basin. There are four box culverts beneath the highway for drainage (2- 1.8 X 1.8 m and 2- 2.4 X 2.4 m). The current speed limit on Hwy 441 is 97 km/h (65 mph). MetTHOoDs—The study took place from August 19, 1998 through August 13, 1999. Surveys consisted of a researcher walking the entire 3.2-km length of the road on three consecutive days per week for 52 weeks. The start date each week was chosen using a computer-generated random numbers table based on Julian date. On day 1, a researcher went out and spray painted all dead animals found, and on days 2 and 3 (sample days) all unmarked roadkills were counted and subsequently marked. By marking dead animals, we were able to obtain a count of the number of dead animals that had accrued during two 24-hour periods per week. The road was divided into 100-m sections for a length of 3.2 km. The area surveyed consisted of the entire road surface (north and southbound lanes) and extended 3-4 m onto the grassy shoulders (1 pass on each side of the road). The median also was surveyed on foot or mountain bicycle (1 pass). Surveys were conducted at dawn and all live and dead animals were recorded. Dead animals were marked with spray paint so that they were not counted more than once. The paint used was both lead and toluene-free (Forestry Suppliers, Jackson, MS). Locations of animals also were recorded, e.g., north or southbound lane, right-of-way, median, and 100-m section. Environmental data were collected midway across the prairie basin and near the south rim. Air temperature (AT), water temperature (WT), relative humidity (RH), and barometric pressure (BP) were measured with computer data loggers (Onset Computer Corporation, Bourne, MA). Water level and rainfall data at Alachua Sink, located in the northwest portion of Paynes Prairie, were provided by FDEP. At the beginning of the study (August 1998) the water level on the prairie was 59.90’ NGVD (National Geodetic Vertical Datum). Water levels peaked in early October at 60.72’ following rains associated with Tropical Storm Georges and declined steadily thereafter, and reached a 12-month low of 56.62’ at the end of the study (Fig. 1). Total rainfall for the year was 924 mm (unpubl. data FDEP, Gainesville, FL). Data Analysis—Kill rates were calculated as the number of kills per 24-hour sampling period (day 2 and 3). A genmod procedure (SAS, 2001) was used to examine interactions between environmental variables (rainfall, AT, WT, BP, and RH), water level (NGVD) and road kill counts for reptiles and amphibians. Mean AT, WT, BP, and RH and total rainfall for the 24-hour period prior to the road survey were used in calculations. Traffic counts for the 3.2-km section were conducted by the Florida Department of Transportation for one 24-hour period per month through the course of the study. ResuLTts—During the 24-hour surveys (n = 105), 1,821 dead vertebrates rep- resenting 62 different species were counted (Table 1). Most of the kills could be identified to the species level (87.4%); however, 7.4% could only be identified to the generic level, and 5.2% could only be categorized by class. Most of the roadkills 130 FLORIDA SCIENTIST [VOL. 66 —a—NGVD —e— Rainfall 62 y 200 = a 60+ + 150 g > ot ae ve ro 58 100 = 2 56 - +50 € 54 po Tf tpt tt t+ 0 OP ASONODJFMAMJJIA Month Fic. 1. Mean monthly water levels and rainfall totals on Paynes Prairie, Alachua County, Florida from August 1998—August 1999. were frogs (45.7%) and snakes (34.2%), whereas turtles, birds, mammals, and alligators comprised 20% of the sample. The green tree frog (Hy/a cinerea) was the most commonly observed species (n = 296), followed by the southern leopard frog (Rana sphenocephala; 230), Florida water snake (Nerodia fasciata pictiventris; 194), pig frog (Rana grylio; 145), and green water snake (Nerodia floridana; 119). These five species represented 54% of all animals killed. An additional 1,545 dead vertebrates (500 frogs, 669 snakes, 1 lizard, 187 turtles, 17 alligators, 126 birds, 45 mammals, including an additional 16 species) were counted on day | of the surveys. The total road length surveyed was 336 km (3.2 km X 105 24-hour sampling units); the number of roadkills per km was 5.41. The 24-hour kill rate (mean number of kills per 24-hour sampling unit) for all vertebrates was 17.3 (SD = 15.5; range = 0-79) (Table 2). Roadkills occurred in all months of the year; however, seasonal patterns in the kill rates were evident. With the exception of birds, most road kills occurred from April through November (Fig. 2). Very high kill rates for frogs and snakes were ob- served in July and August 1999 (15.8 snakes/day and 30.2 frogs/day, respectively). The monthly kill rates for the five most common species are presented in Figs. 3a and 3b. Among the frogs, green treefrogs were most abundant in June, July and August 1999, whereas most pig frogs were killed in April and May. The majority of the pig frogs observed in April and May (88%) were subadults that may have been dispersing after completing metamorphosis in response to declining water levels on the prairie. Southern leopard frogs were killed in the greatest numbers from November through February, although large numbers also were killed in August 1999. The greatest number of Florida water snake kills occurred in August 1998, when water levels were at their highest for the period of record. Large numbers of green water snakes were recorded in July and August 1999. Three gravid green water snakes with 8-24 fully developed young were killed in mid-July. Approximately 50% of the green water snakes killed in July and August were neonates (<30 cm snout-vent length). The kill rate for birds was highest in March (3.6 birds/day) and November (3. 1/ day). The most common birds killed were those that inhabited shrubs along the right-of-way, including yellow-rumped warbler (Dendroica coronata; 19.4%) and No. 2 2003] SMITH AND DODD—PAYNES PRAIRIE ROADKILL iin common yellowthroat (Geothlypis trichas; 7.9%). Two wetland species, the common moorhen (Gallinula chloropus) and least bittern (/xobrychus ixilis) comprised 13.7% of the sample. A black-bellied plover (Pluvialis squatarola) was found dead on the road in May 1999 (on day | of the survey week); this represents the first record of this species for the Preserve. Mammals represented only 1.5% of the sample. Raccoons (Procyon lotor), opossums (Didelphis virginianus), and round-tailed muskrats (Neofiber alleni) represented the majority of mammals killed (66.7%). A summary of the interactions between environmental variables and the num- ber of road kills is presented in Table 3. The variables AT and WT were highly correlated, therefore, only AT was used in the analysis. Significant interactions were detected between BP, RH, and NGVD and number of roadkill frogs. There was a significant relationship between RAIN and turtle kills and NGVD and snake kills. Although there was no clear pattern between the environmental variables measured in this study and the daily kill rate, the numbers of snakes and frogs observed from year to year on the prairie probably is related to local weather conditions (see Main and Allen, 2002). For example, Carr (1974) recalled finding more than 700 snakes on the road and right-of-way following a hurricane in 1941 (at least two thirds of which were injured or dead). Hellman and Telford (1956) also described an event where more than 200 juvenile mud snakes were killed following a 1950 hurricane. The average annual daily traffic volume on U.S. 441 across Paynes Prairie (including both north and southbound traffic) was 12,165 + 994 (FDOT, 1999). Peak traffic in the northbound lanes occurred between 0700 and 0730 hrs and in the southbound lanes from 1630-1700 hrs (Fig. 4). Daily traffic volumes ranged from 11,120 in September 1998 to 14,139 in November 1998. We found no relationship between traffic volume and mean monthly kill rate (t = 0.85, P = 0.417, df = 12, 1” = 0.067). However, traffic data were collected just one day per month and did not necessarily correspond with road sampling. Most carcasses were located on the paved surface of the road (93.9%), whereas only a few were found on the grassy right-of-way (4.56%) and median (1.5%). Carcasses were not evenly distributed on the paved surface of the road, e.g., bicycle, outside, or inside lanes (y? = 65.09; P < 0.0001); most were located in outside lanes. Although kills of most taxa were concentrated in the outside lanes, alligators and birds were more evenly distributed on the roadway (Fig. 5). Nearly twice as many frogs were found in the west (southbound) lanes as compared to east (northbound) lanes, and the reverse was the case for turtles. The number of snake kills was slightly higher in the northbound lanes. The kills were not evenly distributed along the length of the roadway (y° = 9.75; P < 0.005) and it seems likely that the number of kills per 100-m road section was related to the adjacent habitat. The greatest number of kills occurred adjacent to flooded pasture at the base of the north rim of the prairie and the fewest kills occurred in sections which were adjacent to open water habitat. Only 26 live animals were observed during morning road surveys. Eleven were simply basking on the right-of-way [e.g., American alligator (A/ligator mississip- piensis) and Florida cottonmouth (Agkistrodon piscivorus)]; however, the re- mainder was observed attempting to cross the road. Of the 15 vertebrates that tried to 132 FLORIDA SCIENTIST [VOL. 66 TABLE 1. Vertebrate species recorded dead on U.S. Highway 441 across Paynes Prairie, Alachua County, Florida, August 19, 1998—August 13, 1999. Scientific Name Common Name Total Frogs Bufo terrestris southern toad 6 Hyla cinerea green treefrog 296 Hyla squirella squirrel treefrog 1 Hyla sp. unidentified hylid Ae, Rana grylio pig frog 145 Rana sphenocephala southern leopard frog 230 Rana sp. unidentified ranid 62 unidentified frog Da Total: 833 Crocodilians Alligator mississippiensis American alligator 12 Turtles Apalone ferox Florida softshell 4 Chelydra serpentina common snapping turtle 8 Kinosternon bauri striped mud turtle 77 Kinosternon subrubrum eastern mud turtle WS Pseudemys floridana peninsula cooter 16 Pseudemys nelsoni Florida redbelly turtle 13 Sternotherus odoratus common musk turtle 26 Terrapene carolina bauri Florida box turtle 1 Trachemys scripta scripta yellowbelly slider 4 unidentified turtle y28) Total: 187 Snakes Agkistrodon piscivorus conanti Florida cottonmouth 68 Crotalus adamanteus eastern diamondback rattlesnake 1 Elaphe guttata guttata corn snake 3 Elaphe obsoleta quadrivittata yellow rat snake 3 Farancia abacura mud snake 33 Nerodia fasciata pictiventris Florida water snake 194 Nerodia floridana Florida green water snake 119 Nerodia taxispilota brown water snake 1 Opheodrys aestivus rough green snake 2 Regina alleni striped crayfish snake 67 Seminatrix pygaea black swamp snake 83 Storeria dekayi victa Florida brown snake 11 Tantilla relicta neilli central Florida crowned snake 1 Thamnophis sauritus sackenii peninsula ribbon snake 2D) Thamnophis sirtalis sirtalis eastern garter snake 1 unidentified snake i Total: 623 Birds Agelaius phoeniceus red-winged blackbird 1 Bubulcus ibis cattle egret 4 Ceryle alcion belted-kingfisher 1 Coccyzus americanus yellow-billed cuckoo 1 No. 2 2003] TABLE |. Continued. SMITH AND DODD—PAYNES PRAIRIE ROADKILL 133 Scientific Name Common Name Total Cathartes aura turkey vulture 1 Dendroica coronata yellow-rumped warbler i} Dendroica palmarum palm warbler 1 Dumetella carolinensis gray catbird 1 Fulica americana American coot 2 Gallinago gallinago common snipe 1 Gallinula chloropus common moorhen 10 Geothlypis trichas common yellowthroat 11 Ixobrychus exilis least bittern 9 Melospiza georgiana swamp sparrow 10 Mimus polyglottos northern mockingbird 1 Otus asio eastern screech owl 1 Porzana carolina sora 2 Quiscalus major boat-tailed grackle 2) Rallus limicola Virginia rail 1 Sialia sialis eastern bluebird 1 Spizella passerina chipping sparrow 3 Sayornis phoebe eastern phoebe 1 Tachycineta bicolor tree swallow 4 Thryothorus ludovicianus Carolina wren 3 Zenaida macroura mourning dove 1 unidentified bird 39 Total: 139 Mammals Canis familiaris domestic dog 1 Myotis austroriparius southeastern myotis 1 Dasypus novemcinctus nine-banded armadillo 1 Didelphis virginianus opossum 6 Neofiber alleni round-tailed muskrat 5 Procyon lotor raccoon 7 Sigmodon hispidus hispid cotton rat 1 unidentified mammal 5 Total: Zi Grand Total: 1,821 cross the road, seven were injured or killed, five turned away from the road and returned to the prairie, and three crossed successfully. The three animals that successfully crossed the road were a red fox (Vulpes vulpes), a Florida box turtle (Terrapene carolina bauri), and a common snapping turtle (Chelydra serpentina). The red fox crossed quickly during a break in heavy traffic, whereas the two turtles crossed on weekend days, when traffic volume was quite low. Boat-tailed grackles (Quiscalus major) were the most common diurnal scavengers observed in the vicinity of the road. They were seen feeding on the carcasses of a Florida water snake, common musk turtle (Sternotherus odoratus), and green treefrog. Nine boat-tailed grackles and one turkey vulture (Cathartes aura) were found dead on the road and presumably were hit while foraging on 134 FLORIDA SCIENTIST [VOL. 66 TABLE 2. Total number of kills and kill rates for vertebrates on U.S. Highway 441 across Paynes Prairie, Alachua County, Florida, from August 1998—August 1999. Number Killed Kills/km 24-hour Kill rate Frogs 833 2.48 793 Alligators 12 0.04 0.11 Turtles 187 0.55 1.78 Snakes 623 1.85 5.93 Birds 139 0.41 132) Mammals DF 0.08 0.26 Total 1821 5.42 17.33 the roadway. Nocturnal scavengers could include Florida cottonmouth, raccoon (Procyon lotor), and opossum (Didelphis virginianus), all of which were found dead on the road. Discussion—Based on the mean kill rate determined in this study (17.3 vertebrates/day), the estimated mortality for the year (1998-1999) was 6,314 animals (2,894 frogs; 2,164 snakes; 650 turtles; 482 birds; 95 mammals; and 40 B Alligators & Mammals @ Birds O Turtles § Snakes wm Frogs 30 - Zoe @® & =F = 5 15- <= x 10- _ \ N N ; \ N (ep) é Months Fic. 2. Monthly distribution of road kills on U.S. Highway 441 across Paynes Prairie (August 1998—August 1999). No. 2 2003] SMITH AND DODD—PAYNES PRAIRIE ROADKILL 135 @ Hci Z Rut Ror 14 2 2 40. ~ = 8, < = aa 5 re) = Ses? | y Y) Gy D J F M A M J J A £ 6 ~ < | =) 5 | “ oI LLL aA Bini oe) Foes A om ved JCA Month Fic. 3. (a) Monthly distribution of Hyla cinerea (Hci), Rana sphenocephala (Rut), and Rana grylio (Rgr) kills on U.S. Highway 441 across Paynes Prairie, Alachua County, Florida. (b) Monthly distribution of Nerodia fasciata pictiventris (Nfa) and Nerodia floridana (Nfl) kills on U.S. Highway 441 across Paynes Prairie, Alachua County, Florida. alligators). Although these estimates should be interpreted with caution because of the high degree of variation in the kill rate among sampling periods, we suspect they may be an underestimate of actual mortality levels. Scavengers undoubtedly consumed some of the sample and some animals may have left the roadway after being hit. Prior to our survey, staff at Paynes Prairie State Preserve documented more than 25,000 dead vertebrates on U.S. 441 over a nine-year period (unpubl. data FDEP, Gainesville, FL). Again, we suspect that these numbers are an underestimate of the true mortality levels, because the FDEP surveys were opportunistic rather than systematic. Furthermore, these surveys were conducted from moving vehicles and smaller vertebrates probably went unseen. Nonetheless, these estimates are im- pressive. To our knowledge, U.S. 441 at Paynes Prairie appears to have one of the highest levels of mortality of road-killed snakes ever reported; snakes were observed at a rate of 1.854 individuals per km surveyed (336 km surveyed/623 snakes killed). This rate is much greater than that reported for Paynes Prairie by Franz and Scudder (1977), who observed 0.295 snakes/km over a 58-month period. The difference in the 136 FLORIDA SCIENTIST [VOL. 66 TABLE 3. Interactions between environmental variables and number of road kills for frogs, turtles, and snakes on U.S. Highway 441 across Paynes Prairie. Data were collected two days per week from 18 August 1998-13 August 1999. Environmental variables included: AT = air temperature, WT = water temperature, BP = barometric pressure, RH = relative humidity, NGVD = national geodetic vertical datum, RAIN = rainfall. Mean AT, WT, BP, and RH and total rainfall for the 24-hour period prior to the road survey were used in calculations. Frogs Turtles Snakes Variable N F Value Pe E F Value Pr > F F Value Pr >F AT 103 ZAY 0.1445 0.14 0.7130 |essy2 0.2203 BP 103 11.64 0.0010 0.79 0.3764 0.44 0.5094 RH 103 48.29 <0.0001 223 0.1394 0.05 0.8318 NGVD 103 5.87 0.0174 0.42 0.5183 AD 0.0429 RAIN 103 0.65 0.4216 6.23 0.0145 0.91 0.3421 observation rates between the two surveys may be due to the fact that Franz and Scudder (1977) conducted surveys from a moving vehicle, whereas we walked the entire paved roadway, median, and right-of-way. Furthermore, the daily traffic volume on U.S. 441 has more than doubled since the Franz and Scudder study (FDOT, unpubl. data.), thus more snakes are likely being killed than in the past. In other snake roadkill studies, observation rates were lower still. For example, Dodd and co-workers (1989) reported an observation rate of only 0.007 snakes/km in northwestern Alabama and observation rates of 0.010 and 0.016 have been reported for roads in New Mexico (Campbell, 1953; Price, 1983). Rosen and Lowe (1994) reported slightly higher values for snakes in the Sonoran Desert 0.0322 (3.22 DOR/ 100km). Bernardino and Dalrymple (1992) found large numbers of dead snakes on a stretch of road through a seasonally inundated prairie in Everglades National Park (784 dead snakes in one year on an 11.5-km stretch of highway). However, the number of survey passes conducted in this study is not reported. Main and Allen (2002) recorded 0.0103 DOR snakes/km along a 48 km highway corridor in Lee County, Florida. Unfortunately there is no way to make a direct comparison between our results and those of past studies to determine if snake numbers on Paynes Prairie are declining. However, anecdotal accounts seem to suggest that this may be the case. For example, Beck (1938) reported finding 588 dead Florida green water snakes in just six visits to the road. Carr (1974) describes the observation of more than 700 snakes on U.S. 441 across Paynes Prairie following a 35.5-cm rain event in 1941. There have been no recent accounts of such concentrations of snakes along the roadway. Roadkills have long been used as a source of information about the distribution and biology of species (Fitch, 1949; Campbell, 1953; van Gelder, 1973; Case, 1978; Sullivan, 1981). The long-term study on snake movements on the prairie performed by Franz and Scudder (1977) and our more recent survey provides the opportunity to make general comparisons of changes in species composition over time. For example, we recorded 15 species of snakes as compared to 12 found by Franz and Scudder (1977) during their 5-year survey. All of the five “new” species recorded in our study were rare (<5 occurrences). Two of the five species, the eastern No. 2 2003] SMITH AND DODD—PAYNES PRAIRIE ROADKILL 137 —@— N bound —m~—S bound Number of Cars Time of Day Fic. 4. Average hourly traffic volume on U.S. Highway 441 at Paynes Prairie State Preserve, from September 1998—August 1999 (FDOT, 1999). diamondback rattlesnake (Crotalus adamanteus) and the Florida crowned snake (Tantilla relicta neilli) are upland species that were found on the rim of the prairie. Franz and Scudder’s (1977) survey was confined to the prairie basin, thus explaining the lack of these species in their sample. A third species, the corn snake (Elaphe guttata guttata), also typically occurs in terrestrial habitats, but two of the three specimens found in our study were located in the prairie basin. A fourth species, the rough green snake (Opheodrys aestivus) inhabits vegetation lining streams or lakes (Conant and Collins, 1998). Both of these species might be expected to use edge habitat created by the road. The fifth ““new”’ species recorded in our study, the brown water snake (Nerodia taxispilota) is a highly arboreal aquatic species that typically occurs along the banks of rivers or streams; its occurrence on the prairie basin is somewhat unusual. The only species reported by Franz and Scudder (1977) that was not found in our study was the eastern kingsnake (Lampropeltis getula). Franz and Scudder found only one eastern kingsnake in 1975; however, Carr (1940) and Kauffeld (1957) described the ease with which this species was collected in the past. Most observations of eastern kingsnakes occurred prior to the highway being widened to four lanes in 1957. Prior to 1957, the road shoulder contained exposed lime rock that may have offered ideal habitat for kingsnakes or their prey (Franz, 1998). Five species—the Florida banded water snake, Florida green water snake, striped crayfish snake (Regina alleni), black swamp snake (Seminatrix pygaea), and mud snake (Farancia abacura)—dominated the sample during the Franz and Scudder (1977) surveys, although the ranking within this group varied among years. The most obvious difference between our survey and that of Franz and Scudder is the increase in numbers of Florida cottonmouth killed. This species represented <5% of the sample in all 5 years of the Franz and Scudder study, whereas it represented nearly 16% of our sample. Again, changes in the habitat along the right-of-way may favor this species. Striped crayfish snake numbers were quite variable in the Franz and Scudder survey (53.6% of the sample in 1974 versus 2.6% of the sample in 1975). Striped crayfish snakes represented approximately 11% of our sample, but immediately prior to the study (Spring 1998), during a period of extremely high water, large numbers of striped crayfish snakes were killed (Weimer, 1998). 138 FLORIDA SCIENTIST [VOL. 66 m@ ROW BL OUT OCL F..9 (Cows 4S Brive "aii Taxonomic Group = MED % of Total Fic. 5. Location of kills by lane on U.S. Highway 441 across Paynes Prairie, Alachua County, Florida. F = frogs, C = alligators, T = turtles, S = snakes, B = birds, M = mammals; ROW = grassy right-of-way, BL = bicycle lane, OUT = outside traffic lane, CL = center line; IN = inside traffic lane, MED = grassy median. Given the extremely high traffic volume on Highway 441, we suspect that virtually all animals that attempt to cross the road during peak traffic hours are killed, regardless of minor fluctuations in daily traffic levels. The few animals observed crossing the road successfully in this study did so during non-peak hours or were extremely swift-footed (e.g., red fox). It seems likely that slow-moving species such as most aquatic snakes, ranid frogs, or turtles would be especially susceptible to being hit by motor vehicles. Franz and Scudder (1977) monitored the fate of 132 snakes attempting to cross U.S. 441 at night. They found that only eight of the snakes survived, and that they did so by returning to the prairie, roughly where they left it. In addition, they reported finding very few snakes in the median during their weekly surveys, and suggested that few snakes were able to successfully reach the median. The low number of carcasses found in the median during our study further supports this conclusion. The majority of the species killed on U.S. 441 at Paynes Prairie were ‘common’, widely distributed species and road mortality is unlikely to impact these species at more than a local level. However, since the road may present an impenetrable barrier to some species, there may be important demographic and genetic consequences (Forman and Alexander, 1998). There has been concern in the scientific community about the effects of roads on wildlife for a number of years (Stoner, 1925; Dickerson, 1939). However, the magnitude of the impacts of roads on animal populations has proven difficult to quantify, primarily because impacts cannot be assessed without corresponding data on species abundance. Transportation managers and engineers have conceived of a variety of ways to prevent or reduce highway-related wildlife mortality because animals killed on roads represent a drain on adjacent populations, and because of increasing public pressure to do something about the problem. These efforts are most advanced in Europe, where the problems associated with road-related wildlife mortality have long been recognized (Langton, 1989; ALASV, 1994; Percsy, 1995). Rather than simply cata- loguing mortality, biologists are now in a position to recommend solutions based on carefully collected life history data, particularly on habitat use and activity patterns. These data will prove more vital in the design of ecopassages and barriers to reduce or prevent road-related mortality. No. 2 2003] SMITH AND DODD—PAYNES PRAIRIE ROADKILL 139 ACKNOWLEDGMENTS—This study was funded by the Florida Department of Transportation and we thank Gary Evink and Pete Southall for their support of the project. We are grateful to Jack Gillen, Dan Pearson, and Jim Weimer with the Florida Department of Environmental Protection for providing environmental data and unpublished roadkill counts for Paynes Prairie. We also thank Dick Franz and Sylvia Scudder for making their unpublished data available to us. Elizabeth Domingue assisted in the preparation of the study plan. David O’Neill, Elizabeth Domingue, Marissa Scott, and Theresa Cessenich assisted in field surveys. Salvaged roadkill specimens were donated to the Florida Museum of Natural History at the University of Florida (GFC Collecting Permit # WS98348). Tom Webber, Candace McCaffery, and Laurie Wilkens helped with the identification of birds and small mammals. LITERATURE CITED ALASV (Arbeitsgruppe unter Leitung der Abteilung Strafenbau des Verkehrsministeriums). 1994. Amphibienschutz. Leitfaden fiir Schutzmafnahmen an StraBen. Schrifttenreihe der Stra- Benbauverwaltung Baden Wiirttemberg, Heft 4. Beck, W. M. 1938. Notes on the reptiles of Payne’s Prairie, Alachua County, Florida. Florida Nat. 11: 85-87. BERNARDINO, F. S. AND G. H. DALRYMPLE. 1992. Seasonal activity and road mortality of the snakes of the Pa-hay-okee wetlands of Everglades National Park, USA. Biol. Conserv. 62:71-75. CAMPBELL, H. 1953. Observations on snakes DOR in New Mexico. Herpetologica 9:157—160. Carr, A. F. 1940. A contribution to the herpetology of Florida. Univ. Fla. Biol. Sci. Ser. 3, 1-118. . 1974. The Reptiles. Time-Life Books, New York, NY. Case, R. M. 1978. Interstate highway road-killed animals: a data source for biologists. Wildl. Soc. Bull. 6:8—13. CONANT, R. AND J. T. Couns. 1998. A Field Guide to Reptiles and Amphibians: Eastern and Central North America. Houghton Mifflin Company, Boston, MA. Dickerson, L. M. 1939. The problem of wildlife destruction by automobile traffic. J. Wildl. Manage. 3:104-116. Dopp, C. K., JR., K. M. ENGE, AND J. N. Stuart. 1989. Reptiles on highways in north-central Alabama, USA. J. Herpetol. 23:197—200. Fitcu, H. S. 1949. Road counts of snakes in western Louisiana. Herpetologica 5:87—90. FLORIDA DEPARTMENT OF ENVIRONMENTAL PROTECTION (FDEP). 1989-1997. unpublished data. FLORIDA DEPARTMENT OF TRANSPORTATION (FDOT). 1999. Station Counts AADT History, unpublished traffic counts for SR 25, Alachua County, FL. FORMAN, R. T. T. AND L. E. ALEXANDER. 1998. Roads and their major ecological effects. Annu. Rev. Ecol. Syst. 29:207-231. FRANZ, R. AND S. J. ScuppER. 1977. Observations of snake movements on a north Florida highway. Unpublished Report. Florida State Museum. University of Florida. Gainesville, FL. . 1998. Florida Museum of Natural History, University of Florida, Gainesville, FL. Pers. Commun. HELLMAN, R. E. AND S. R. TELFORD. 1956. Notes on a large number of red-bellied mudsnakes, Farancia a. abacura, from northcentral Florida. Copeia 1956:257—258. KAUFFELD, C. 1957. Snakes and Snake Hunting. Hanover House, Garden City, NY. KUSHLAN, J. A. 1980. Freshwater marshes. Pp. 324-363. In: Myers, R. L. AND J. Ewe (eds). Ecosystems of Florida. University of Central Florida Press, Orlando, FL. LANGTON, T. E. S. (ed.). 1989. Amphibians and Roads. ACO Polymer Products, Ltd. Shefford, England. Main, M. B. AnD G. M. ALLEN. 2002. Landscape and seasonal influences on roadkill of wildlife in southwest Florida. Florida Sci. 65:149-158. Percsy, C. 1995. Les Batraciens sur nos Routes. Ministére de la RégionWallonne, Service de la Conservation de la Nature et des Espaces verts. Brochure technique No. 1. Wallonne, Belgium. Price, A. H. 1983. Roadriding as a herpetofaunal collecting technique and its impact upon the herpetofauna of New Mexico, unpublished report to Endangered Species Program, New Mexico Department of Game and Fish. 140 FLORIDA SCIENTIST [VOL. 66 Rosen, P. C. AND C. H. Lowe. 1994. Highway mortality of snakes in the Sonoran desert of southern Arizona. Biol. Conserv. 68:143—148. SAS. 2001. SAS User’s Guide. SAS Institute Inc., Cary, NC. STONER, D. 1925. The toll of the automobile. Science 61:56—57. SULLIVAN, B. K. 1981. Distribution and relative abundance of snakes along a transect in California. J. Herpetol. 15:247-248. VAN GELDER, J. J. 1973. A quantitative approach to the mortality resulting from traffic in a population of Bufo bufo L. Oecologia 13:93—95. WEIMER, J. 1998. Florida Department of Environmental Protection, Paynes Prairie State Preserve, Micanopy, FL. Pers. Commun. Florida Scient. 66(2): 128-140. 2003 Accepted: September 25, 2002 Biological Sciences DISTRIBUTION OF THE INTRODUCED BLACK SPINY-TAILED IGUANA (CTENOSAURA SIMILIS) ON THE SOUTHWESTERN COAST OF FLORIDA KENNETH L. Krysko™, F. WAYNE Kino”, Kevin M. EnceE™, AnD ANTHONY T. Reppas‘” “Florida Museum of Natural History, Division of Herpetology, P.O. Box 117800, University of Florida, Gainesville, FL 32611 Florida Fish and Wildlife Conservation Commission, Joe Budd Wildlife Field Office, 5300 High Bridge Road, Quincy, FL 32351 ABsTRACT: The black spiny-tailed iguana (Ctenosuara similis) was introduced onto Gasparilla Island in southwestern peninsular Florida ca. 30 years ago. Since then, this exotic species has undergone both natural and human-mediated range expansion, and it is presently found in Placida, Cape Haze, Gulf Cove, Cayo Costa, Keewaydin Island, and Little Marco Island. Although C. similis is primarily herbivorous, it will feed opportunistically on small animals, including insects, crabs, rodents, fishes, nestling birds, bird eggs, and hatchling sea turtles. Because of the possible ecological impacts of C. similis on Florida’s native flora and fauna, population monitoring and/or eradication efforts should be conducted on C. similis. Key Words: Iguana, Ctenosaura similis, Ecology, Florida, Gasparilla Island, Keewaydin Island THE IGUANID genus Cfenosaura consists of 13 species native to central and southern Mexico, the Yucatan Peninsula, and Central America (K6hler et al., 2000). Ctenosaurs or spiny-tailed iguanas have been introduced into the United States in southern Texas and southern peninsular Florida (Eggert, 1978; Behler and King, 1979; Wilson and Porras, 1983; Stiling, 1989; Conant and Collins, 1991; Dalrymple, 1994; Angell, 1996; Butterfield et al., 1997; Bartlett and Bartlett, 1999; McKercher, 2001). The black spiny-tailed iguana (Cfenosuara similis) was first reported to have an established population along Old Cutler Road in Miami-Dade County (Eggert, 1978). However, Wilson and Porras (1983) stated that this population was misidenti- fied and consisted of the Mexican spiny-tailed iguana (C. pectinata). Nonetheless, recent surveys on and near Gasparilla Island on the southwestern coast of Florida have identified established populations of C. similis that are undergoing natural and human-mediated range expansion. Herein, we present records of C. similis from Charlotte, Collier, and Lee counties, Florida. MetHops—Gasparilla Island, an approximately 10.5-km long barrier island southwest of Port Charlotte, is separated from the mainland by Charlotte Harbor and Gasparilla Sound. Gasparilla Island is connected to the mainland at Placida via the Boca Grande Causeway, which stretches over two small uninhabited causeway islands and three bridges before reaching Gasparilla Island. The approximate 141 142 FLORIDA SCIENTIST [VOL. 66 TABLE 1. Black spiny-tailed iguanas (Ctenosaura similis) collected from southwestern peninsular Florida. County Location Date Collector(s) Voucher This Study Lee Gasparilla Island 25 June 2002 K.L. Krysko, F.W. King, UF 133211-17 K.M. Enge Lee Gasparilla Island 27 June 2002 K.L. Krysko, F.W. King, UF 133254 K.M. Enge Other Specimens Charlotte | Gasparilla Island June 1994 P.E. Moler UF 91662 Collier Keewaydin Island, 20 June 2000 S.M. Bertone UF 128412 Rookery Bay Estuarine Research Reserve ee Gasparilla Island 2 June 2000 K. Mebert UF 121140-43 northern one-third of Gasparilla Island is situated in Charlotte County, whereas the southern two-thirds is in Lee County. Records of C. similis are based on recent captures and observations during three survey days on the southwestern Florida coast between December 2000 and June 2002. Additional records were gathered by querying the Department of Environmental Protection (DEP) personnel and exotic species database (Florida Department of Environmental Protection, 2002). Captures were made during the daytime using noose carpets and blowguns with tapered corks. Because only C. pectinata has been previously reported from Gasparilla Island (Angell, 1996; Bartlett and Bartlett, 1999; McKercher, 2001), the possibility of encountering this species was also considered, and we attempted to verify species identification via observation if an individual was not collected. Ctenosaura similis and C. pectinata are closely related species but differ in a number of morphological and molecular characters (KGhler and Streit, 1996; Kohler et al., 2000). Ctenosaura similis has 0-2 (usually zero) scales separating the dorsal and caudal crests, two complete rows of intercalaries between whorls of enlarged caudal scales near the base of the tail, and some (usually a high) degree of dark dorsal crossbands (Kohler and Streit, 1996). Ctenosaura pectinata has 2—14 scales separating the dorsal and caudal crests, three complete rows of intercalary scales between whorls of enlarged caudal scales near the base of the tail, and no dark dorsal crossbands. Identification of juveniles is more problematic, as both species tend to be green to gray with dark crossbands. However, the number of scales separating the dorsal and caudal crests, as well as the intercalary characters, hold for all age classes and were used for species identification of juveniles. Voucher specimens and photographs were deposited in the Florida Museum of Natural History (FLMNH), University of Florida (UF collection). RESULTS—We recorded >200 C. similis on Gasparilla Island. Eight specimens were collected (Table 1) consisting of juveniles and adults of both sexes. We observed at least two individuals on each Boca Grande Causeway island (26°48.907'N, 082°16.439'W and 26°49.543’'N, 082°16.223'W) and three individ- uals on the mainland at Placida (26°49.790'N, 082°16.172'W). No C. pectinata were recorded in our surveys. Five additional C. similis from Gasparilla Island and one from Keewaydin Island, Collier County, were found in the UF collection. Eighteen individuals from Gasparilla Island and one from Cayo Costa were recorded in the DEP exotic species database (Florida Department of Environmental Protection, 2002), and numerous individuals were recorded from Keewaydin Island (Bertone, 2002). No. 2 2003] KRYSKO ET AL.—SPINY-TAILED IGUANA 143 DiscussiIoN—Because no C. pectinata were recorded in our surveys, we believe that the Gasparilla Island population was misidentified in earlier reports. McKercher (2002) assumed C. pectinata was the species found on Gasparilla Island based entirely on the field guide identification by Bartlett and Bartlett (1999), yet she collected no voucher specimens during her study. Photographs labeled as C. pectinata by Angell (1996) and Bartlett and Bartlett (1999) are misidentified and clearly C. similis. Four individuals labeled as green iguanas (/guana iguana) in the DEP exotic species database are undoubtedly C. similis as described in their remarks (Florida Department of Environmental Protection, 2002). Despite the fact that ctenosaurs on Gasparilla Island have been consistently identified as C. pectinata, there is no evidence that C. pectinata ever existed in this area. Ctenosaura similis on Gasparilla Island appears to have originated from a single introduction. In the late 1970s—early 1980s an island resident brought back from Mexico three C. similis (McKercher, 2001; Amen, 2002; Middleton, 2002), which were raised by his children for the next few years before being released near the Range Light House (Amen, 2002; Middleton, 2002). The ctenosaurs remained localized for several years but began to reproduce and slowly spread from the point of introduction (Middleton, 2002). Presently, our data illustrate a large, well- established population of C. similis throughout the entire island, on both Boca Grande Causeway islands, and on the mainland at Placida. Individuals have also been found dead-on-road (DOR) after being hit by vehicles on the Boca Grande Causeway bridges (McKercher, 2002), suggesting that the species reached the mainland naturally. Additionally, individuals have been taken from Gasparilla Island to the mainland by workers (Middleton, 2002), which could assist in a more rapid range expansion of C. similis on the mainland. Middleton (2002) found a ctenosaur under the hood of her car after driving home from Gasparilla Island State Park on a cold afternoon. Individuals have now been reported from Cape Haze north of Placida (Middleton, 2002), Gulf Cove, Cayo Costa to the south of Gasparilla Island (Florida Department of Environmental Protection, 2002), and Keewaydin Island in the Rookery Bay Estuarine Research Reserve ca. 80 km south of Gasparilla Island (Bertone, 2002) (Table 1). Ctenosaura similis was probably transported purposely to Cayo Costa, which is accessible only by boat. Ctenosaura similis on Keewaydin Island also appears to have originated from a single introduction. A private landowner on Keewaydin Island released 5—30 C. similis on his property on the southern end of the island in the summer of 1995 (Bertone, 2002). No C. similis were reported until April 1998, when island residents began reporting ctenosaurs causing landscape destruction ca. 1 km north of the introduction site (Bertone, 2002). In the summer of 1998, numerous hatchling and adult C. similis were reported from the southern tip of the island north to Johns Pass on the northern half of the island ca. 8 km north of the introduction site (Bertone, 2002). Presently, C. similis is found on the entire Keewaydin Island and adjacent Little Marco Island. The range expansion and ecological status of C. similis should be of particular interest to conservationists in Florida. Ctenosaura similis has been reported to produce 5-8 clutches annually (Ojasti, 1996), each consisting of 12-88 (mean 43) 144 FLORIDA SCIENTIST [VOL. 66 eges (Wiewandt, 1982). One specimen (UF 131496) collected by us on 27 March 2002 at Crandon Park on Key Biscayne had 82 well-developed eggs in her oviducts. Ctenosaurs are primarily herbivorous but will feed opportunistically on small animals, including insects, crabs, rodents, fishes, nestling birds, bird eggs, and hatchling sea turtles (Evans, 1951; Fitch et al., 1971; Alvarez del Toro, 1982; Smith, 1990; Smith et al., 1992; Rodriguez-Juarez and Cepeda, 1998; Arndt, 1999; Durtsche, 2000; McKercher, 2001). Ctenosaura similis on Keewaydin Island pose a threat to eggs and nestlings of the least tern (Sterna antillarum) (Zambrano, 2002), a threatened species in Florida. On 16 June 1998, Rookery Bay National Estuarine Research Reserve staff observed an adult C. similis chasing baby and adult least terns on the beach on the southern tip of Keewaydin Island (Bertone, 2002). Least terns, Wilson’s plovers (Charadrius wilsonia), and snowy plovers (C. alexandrinus) nest on the northern end of Gasparilla Island, which is also inhabited by ctenosaurs (Douglass, 2002). Keewaydin Island is also used by nesting loggerheads (Caretta caretta) (Meylan et al., 1995), but their eggs are probably safe from ctenosaurs because of the depth at which they are laid. On Gasparilla Island, C. similis occupies the same habitats and feeds on the same native vegetation as gopher tortoises (McKercher, 2001). It also utilizes tortoise burrows but has not been observed to cohabit with tortoises (McKercher, 2001). If C. similis ever becomes established in Cape Coral, Lee County, it could impact the largest population of burrowing owls (Athene cunicularia floridana) in Florida (Millsap and Bear, 2000) by competing for burrows or even preying upon nestlings. Although C. similis is considered an attraction by some residents and visitors on Gasparilla Island, the species has also proven a nuisance, as evidenced by the lizard foraging on native plants and the thousands of dollars spent each year by homeowners because of damage to their houses and landscape vegetation (Angell, 1996; McKercher, 2001). We believe that the C. similis populations and _ their ecological impacts should be monitored and efforts should be initiated to control populations in areas where detrimental impacts on sensitive native flora and fauna are documented. ACKNOWLEDGMENTS—We would like to thank Reggie Norman, Ken Alvarez, Chris Angel (Gasparilla Island State Park), and Patty Middleton (Boca Grande Lighthouse Museum) for assistance, allowing us to collect specimens, and historical data; Elizabeth McKercher and Konrad Mebert for miscellaneous information; Josiah H. Townsend and Reggie Norman for assistance in obtaining literature; Terry Hingtgen (Florida Park Service) for DEP data; and Steve Bertone (Rookery Bay National Estuarine Research Reserve) and Paul Moler (Florida Fish and Wildlife Conservation Commission) for information and specimens from Keewaydin Island. Paul Moler and Jeff Gore reviewed this manuscript. LITERATURE CITED ALVAREZ DEL Toro, M. 1982. Los Reptiles de Chiapas. Instituto de Historia Natural, Tuxtla Gutierrez. 248 pp. AMEN, B. 2002. Florida Department of Environmental Protection, Gasparilla Island State Park, Boca Grande, FL. Pers. Comm. ANGELL, K. 1996. Nightmare of the iguana? Boca Beacon 17(40):1+4. No. 2 2003] KRYSKO ET AL.—SPINY-TAILED IGUANA 145 ArnptT, R. G. 1999. Predation by the black iguana (Cfenosaura similis) on the painted ghost crab (Ocypode gaudichaudii) in Costa Rica. Florida Scient. 62:111—114. BartTLeTT, R. D. AND P. P. BARTLETT. 1999. A Field Guide to Florida Reptiles and Amphibians. Gulf Publishing, Houston, TX. 280 pp. BEHLER, J. L. AND F. W. Kinc. 1979. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, New York, NY. 719 pp. BERTONE, S. M. 2002. Florida Department of Environmental Protection, Rookery Bay National Estuarine Research Reserve, Naples, FL. Pers. Comm. BUTTERFIELD, B. P., W. E. MESHAKA, JR., AND C. Guyer. 1997. Nonindigenous amphibians and reptiles. Pp. 123-138. Jn: Stmpertorr, D., D. C. SCHMITZ, AND T. C. BROwn (eds.). Strangers in Paradise: Impact and Management of Nonindigenous Species in Florida. Island Press, Covelo, CA. CONANT, R. AND J. T. CoLiins. 1991. A Field Guide to Reptiles and Amphibians of Eastern and Central North America (3rd Ed.). Houghton Mifflin Co., Boston, MA. 450 pp. DALRYMPLE, G. H. 1994. Non-indigenous amphibians and reptiles in Florida. Pp. 67-71, 73-78. In: ScumiTz, D. C. AND T. C. BROWN (project directors). An Assessment of Invasive Non-indigenous Species in Florida’s Public Lands. Florida Dept. Environ. Protect. Tech. Rept. No. TSS-94-100, Tallahassee. Douc ass, N. J. 2002. Florida Fish and Wildl. Conserv. Comm., Lakeland, FL. Pers. Comm. DurtTscHE, R. D. 2000. Ontogenetic plasticity of food habits in the Mexican spiny-tailed iguana, Ctenosaura pectinata. Oecologia 124:185—195. EacerT, J. 1978. The invasion of the wish willy. Florida Wildl. 31:9-10. Evans, L. T. 1951. Field study of the social behavior of the black lizard, Ctenosaura pectinata. Amer. Mus. Novitates No. 1493:1—26. Fircu, H. S., A. V. Fitcu, AND C. W. Fircu. 1971. Ecological notes on some common lizards of southern Mexico and Central America. Southwest. Natur. 15:397—399. FLORIDA DEPARTMENT OF ENVIRONMENTAL PROTECTION. 2002. Florida Park Serv. District 4 Wildl. Database. KOHLER, G. AND B. Streit. 1996. Notes on the systematic status of taxa acanthura, pectinata, and similis of the genus Crenosaura (Reptilia: Sauria: Iguanidae). Senckenbergiana Biologica. 75:33-43. , W. SCHROTH, AND B. StreIT. 2000. Systematics of the Crenosaura group of lizards (Reptilia: Sauria: Iguanidae). Amphibia-Reptilia 21:177-191. McKercuer, E. 2001. Ctenosaura pectinata (Iguanidae) on Gasparilla Island, Florida: Colonization, habitat use and interactions with Gopherus polyphemus. M.S. Thesis, Univ. Florida, Gainesville. LST pp: . 2002. U.S. Geological Survey, Gainesville, FL. Pers. Comm. MEYLAN, A., B. SCHROEDER, AND A. Mosier. 1995. Sea turtle nesting activity in the State of Florida 1979- 1992. Florida Mar. Res. Publ. No. 52. 51 pp. MIDDLETON, P. 2002. Boca Grande Lighthouse Mus., Boca Grande, FL. Pers. Comm. Mititsap, B. A. AND C. BEAR. 2000. Density and reproduction of burrowing owls along an urban development gradient. J. Wildl. Manage. 64:33-41. Osasti, J. 1996. Wildlife utikzation in Latin America: Current situation and prospects for sustainable management. Rome: Food and Agriculture Organization of the United Nations. FAO Conservation Guide 25, 237 pp. RODRIGUEZ-JUAREZ, C. AND J. L. O. CepeDA. 1998. Ctenosaura pectinata (brown iguana). Diet. Herpetol. Rev. 29:100. SmitH, G. W. 1990. Survey of sea turtle nesting on Ambergris Cay, Belize. Unpubl. Rept. to Belize Audubon Society and Belize Fisheries Department. 8 pp. , K. L. Eckert, AND J. P. Gipson. 1992. WIDECAST Sea Turtle Recovery Action Plan for Belize (Eckert, K. L., ed.). CEP Technical Report No. 18. UNEP Caribbean Environment Programme, Kingston, Jamaica. 86 pp. STILING, P. 1989. Exotics: biological invasions. Florida Wildl. 43(5):13-16. Wiewanpt, T. A. 1982. Evolution of nesting patterns in iguanine lizards. Pp. 119-141. Jn: BURGHARDT, G. M. ANDA. S. RAND (eds.), Iguanas of the World. Noyes Publ., Park Ridge, NJ. 146 FLORIDA SCIENTIST [VOL. 66 WILson, L. D. AND L. Porras. 1983. The ecological impact of man on the South Florida herpetofauna. Univ. Kansas Mus. Nat. Hist. Spec. Publ. No. 9, Lawrence, KS. 89 pp. ZAMBRANO, R. 2002. Florida Fish and Wildl. Conserv. Comm., West Palm Beach, FL. Pers. Comm. Florida Scient. 66(2): 141-146. 2003 Accepted: October 1, 2002. Biological Sciences SEED DISPERSAL BY GOPHERUS POLYPHEMUS AT ARCHBOLD BIOLOGICAL STATION, FLORIDA (2) ) Jane E. Cartson“*, Eric S. MencES™, AND PETER L. Marxks® “Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803 USA Archbold Biological Station, P.O. Box 2057, Lake Placid, FL 33862 USA © Department of Ecology and Evolutionary Biology, Cornell University, 427 Corson Hall, Ithaca, NY 14853 USA ABSTRACT: We investigated the potential for the gopher tortoise (Gopherus polyphemus) to act as an agent of seed dispersal at Archbold Biological Station, Florida. Scat dissections, as well as foraging observations, were used to determine the seed species and plant taxa consumed by the tortoises during June and July 2001. The diet of the gopher tortoise consisted mainly of grasses and sedges, and these, as well as Pinus elliott, Galactia sp., Vaccinium myrsinites, and Gaylussacia dumosa, comprised the majority of the plant matter identified in the scat. Germination tests were performed on digested and undigested seed of the two most abundant seed species found in the scat, the exotic grass Paspalum notatum (bahiagrass) and its native congener, P. setaceum. The percent germination of digested P. notatum seeds was significantly lower than the germination of undigested P. setaceum (<1% vs. 27%). In contrast, many seeds of P. setaceum germinated after digestion, and there was no significant difference between digested and undigested seeds of this species. Gopher tortoises disperse seeds of the exotic P. notatum but suppress immediate germination. They disperse the native grass P. setaceum, which is able to germinate immediately after tortoise digestion. Key Words: Gopher tortoise, Paspalum notatum, Paspalum setaceum, Lake Wales Ridge, diet, herbivory, seed survival THE GOPHER tortoise (Gopherus polyphemus) lives in upland xeric habitats throughout most of the Southeastern Coastal Plain of the United States (Auffenberg and Franz, 1982). Like all other members of the genus Gopherus, gopher tortoises dig and maintain burrows, which protect inhabitants from extreme temperatures, fire, desiccation, and predators (Cox et al., 1987). Gopher tortoise burrows provide habitat for over 350 different vertebrate and invertebrate species, and because of this, the tortoise is considered a keystone species (Cox et al., 1987; Jackson and Milstrey, 1989). The burrows and adjacent mounds of extracted sand also influence the vegetation in these communities by providing favorable microsites for certain plant species (Kaczor and Hartnett, 1990). Though these and many other aspects of the tortoise’s natural history have been well studied, the potential role of the gopher tortoise as a seed disperser has been largely uninvestigated. Seed dispersal by reptiles, or saurochory, is not entirely uncommon, yet has received considerably less attention than dispersal syndromes associated with other * E-mail: jcarlss3@|su.edu 147 148 FLORIDA SCIENTIST [VOL. 66 vertebrates, such as birds and mammals (Moll and Jansen, 1995; Traveset, 1998; Traveset et al., 2001). A growing body of evidence suggests a number of turtles and tortoises play a role in seed dispersal. Two species of herbivorous turtles in Costa Rica (Moll and Jansen, 1995), and the box turtle (Terrapene carolina) (Braun and Brooks, 1987) are known to disperse viable seeds. Furthermore, the germination of seeds was enhanced by passage through the gut of the Galapagos tortoise (Geochelone nigra) (Rick and Bowman, 1961) and Gopherus berlandieri (Rose and Judd, 1982). The herbivorous diet and foraging habits of G. polyphemus, as well as evidence that other tortoises disperse seeds, suggest that the gopher tortoise could very well be dispersing viable seeds. Furthermore, as grasses make up the greatest portion of the tortoise’s diet (Garner and Landers, 1981; MacDonald and Mushinsky, 1988), it is likely that grass seeds would be the most frequently consumed, and therefore, would possess the greatest potential to be dispersed. In a study of the diet of gopher tortoises in a sandhill community, seeds were found in 90% of the examined scat samples, and many of these seeds were identified as grass seeds (MacDonald and Mushinsky, 1988). Gopher tortoises may be agents of dispersal for wiregrass (Aristida sp.), which burns readily and is an important fuel for ground fires in the southeastern U.S. (Auffenberg, 1969). In this way, the gopher tortoise’s role as a seed disperser may contribute to the maintenance of the fire-adapted communities in which it is found. Though it is known that gopher tortoises frequently consume seeds, the viability of seeds found in scat is almost entirely unknown. Ximenia americana, or tallowwood, is the only species to have been tested and found to germinate post- gopher tortoise digestion (Hayes and LeCorff, 1989). However, in Hayes and LeCorff’s study, no comparisons were made between the germination of undigested and digested tallowwood seeds, and hence, it remains unknown if tortoise digestion alters germination percentages in tallowwood seeds, or in seeds of any species. Furthermore, the fleshy tallowwood fruits, which become ripe in the fall, have only been found in the scat of tortoises located in southern Florida (Hayes and LeCorff, 1989). In order to determine if gopher tortoise digestion alters the germination of seed species commonly found in the scat, as well as to examine its overall diet, we addressed the following questions: 1) What plant foods do gopher tortoises eat at Archbold Biological Station in the months June and July? 2) Which seed species are most frequently found in scat? 3) Do the most frequently consumed seeds germinate after passing through a gopher tortoise gut? 4) Is seed germination increased or decreased after passage through the tortoise? Stuby SirE—Archbold Biological Station is located on the southern end of the Lake Wales Ridge, 12.9 km south of Lake Placid in Highlands County, Florida. The normal maximum and minimum temperatures for June and July are 33.4° C and 20.1° C, with 20.6-cm rainfall. All data for this study were collected on the 2,081 ha main property. We studied gopher tortoises along firelanes running through or near various xeric and upland vegetation types: flatwoods, scrubby flatwoods, southern ridge sandhill and human-modified old-field vegetation communities (see Abrahamson et al., 1984, for descriptions of native habitat types). Invasive grasses such as Paspalum notatum (bahiagrass), Panicum sp. and Sporobolis No. 2 2003] CARLSON ET AL.—SEED DISPERSAL 149 indica dominated two human-modified old fields on the property. The 10 to 15 m wide firelanes were typically mowed twice a year and often had ruderal species of grasses and forbs growing along the edges, in addition to species typical of adjacent vegetation types. MeTHops—Data on the diet and seed consumption of the gopher tortoise were obtained through the dissection and analysis of field-collected scat. We collected 91 scat samples in June and July 2001. We located gopher tortoises during 14 hour search intervals between 1000 and 1700 hours along firelanes through or adjacent to scrubby flatwoods, flatwoods, southern ridge sandhill and human modified old- fields. These time periods and locations were chosen in accordance with the periods of highest activity and the preferred habitat of tortoises at Archbold Biological Station (Douglass and Layne, 1978). The tortoises were followed or placed in a wire enclosure until defecation occurred, which usually took place in less than a half-hour. We collected fifty samples in this manner from 34 individuals; the other 41 scat samples were found post-deposition, in the absence of a tortoise, and were collected only if they were completely intact and relatively fresh. We dissected all scat samples within one week of collection and identified plant fragments and seeds to the lowest taxonomic level possible using an on-location herbarium and a reference collection of common plant species found along firelanes and within the adjacent habitat on the station (nomenclature follows Wunderlin [1998]). The leaf and stem matter of grasses and sedges were difficult to tell apart in the scat and were combined into a Poaceae/Cyperaceae category. Though the majority of the grass-like leaves were positively identified as grasses, the presence of some questionable specimens made it necessary to combine the two families. Each plant taxon was counted on a presence or absence basis for each scat, and from this, we calculated the absolute frequency of occurrence of each taxon in the 91 scat samples. To supplement scat analysis, we observed tortoises foraging along firelanes for periods of 10—20 minutes (n = 24) and recorded all plants consumed by the tortoises. The frequency of occurrence in an observation period was calculated using the same method as the scat samples. In order to facilitate comparisons, each observation period was equivalent to one scat sample in that we counted the consumption of a plant taxa only once per observation period. These observations provided information on food plants that were difficult to identify in tortoise scat and also gave another estimate of the plants consumed by the gopher tortoise. We sorted and counted all seeds found in scat samples. For each seed taxon, we calculated the relative frequency of occurrence in the scat samples (number of occurrences of each taxon/total number of occurrences * 100) and the relative density (number of individuals in each taxon/total number of seeds * 100). When 20 or more seeds were found in a single scat sample, we placed seeds on moistened filter paper in petri dishes (10 seeds per dish) within 24 hours of their discovery and monitored subsequent germination. Only two seed species were found in sufficient numbers to be used in the germination trials, Paspalum notatum and P. setaceum. At the outset of each trial, we placed an equal number of fresh, undigested conspecific seeds into petri dishes, to determine if there was a difference in percent germination of digested and undigested seeds. We checked for germination and watered regularly; tests were run outdoors in June-August on a covered veranda. Each of the seven germination tests ran for 45 days, and in the data analysis, we combined all tests on a single species. Germination percentages were compared between digested and undigested seeds using a Fischer’s Exact Chi-square test. RESULTS—Grasses and sedges dominated the summer diet of the gopher tortoise; the leaves of Poaceae/Cyperaceae were present in 97% of the scat samples (Table 1). Three grass species were identified by seed, and these included Paspalum notatum (bahiagrass) and P. setaceum (slender paspalum). In terms of plant fragments, a total of 20 plant genera were found in the 91 scat samples. Slash pine (Pinus elliottii) needles were present in almost 50% of the samples, and Galactia sp. and Vaccinium myrsinites were each found in more than 25% of the scat samples. Of the remaining groups, the most important were Quercus geminata and 150 FLORIDA SCIENTIST [VOL. 66 TABLE |. Frequency of the plant taxa found in Gopherus polyphemus scat (n = 91) or during a 10— 20 minute foraging observation (n = 24). Each plant taxon was counted only once per scat sample and/or once per foraging observation. Taxa with asterisks are grasses identified by seed; the presence of their leaf matter was included in Poaceae (Cyperaceae). Nomenclature follows Wunderlin (1998). Frequency in Frequency in Foraging Plant Taxon Scat (n = 91) Observations (n = 24) Poaceae (Cyperaceae) 96.7% 70.8% Paspalum notatum™ 19.8% — Paspalum setaceum™ 14.3% — Pinus elliottii 48.4% 8.3% Galactia sp. 39.6% 4.2% Vaccinium myrsinites 30.8% 8.3% Quercus geminata 16.5% — Gaylussacia dumosa 15.4% — Roots 12.1% 8.3% Selaginella arenicola 9.9% — Diodia teres TAGe 16.7% Smilax auriculata 5.5% — Mpyrica cerifera 35% aa Digitaria sp." 3.3% — Quercus myrtifolia 2.2% — Unknown herb 2296 — Chamaesyce maculata 2.2% 4.2% Quercus minima 1.1% — Carya floridana 1.1% — Lyonia lucida 1.1% — Lyonia fruticosa 1.1% — Opuntia humifusa 1.1% — Ximenia americana 1.1% — Froelichia floridana — 4.2% Pityopsis graminifolia — 4.2% Tephrosia chrysophylla — 4.2% Mimosa quadrivalvis — 4.2% Licania michauxii (fruit) — 4.2% Commelina erecta — 4.2% Gaylussacia dumosa. Nine genera were found in only one, two or three scat samples. In 89% of the scat samples, all of the plant matter was identified. A comparison of the species composition of observed forage versus species composition of scat revealed many similarities and some notable differences (Table 1). Grasses and sedges were by far the most frequently observed plant taxa eaten by gopher tortoises, consumed in 17 of the 24 observation periods. The exotic bahiagrass was the most commonly consumed plant species, observed in eight of 24 obser- vation periods, and we watched tortoises ingest the seed heads of this species during four of eight observations. The top five taxa of the foraging observation periods were also found in the scat, but their relative frequencies in the scat examinations and the foraging observations were often quite different. Foraging observations showed the highly digestible Diodia teres to be far more frequently consumed than the scat dissections indicated. Furthermore, tortoises were observed eating six plant species No. 2 2003] CARLSON ET AL.—SEED DISPERSAL jl TABLE 2. The seed taxa found in Gopherus polyphemus scat. For each taxon, the relative frequency of occurrence in the scat samples and the relative density were calculated. Relative Frequency Relative Density Seeds Found in Scat (n = 52) (n = 1538) Paspalum notatum 34.6% 72.9% Paspalum setaceum 25.0% 12.6% Diodia teres 13.5% 1.6% Unknown seeds 7.7% 2.2% Digitaria sp. 5.8% 2.3% Pinus elliottii 5.8% 0.3% Chamaesyce maculata 3.8% 8.1% Quercus geminata 3.8% 0.2% that were never identified in scat samples (Table 1). Each of these taxa was recorded only once during the 24 foraging observation periods. Strong evidence exists that gopher tortoises were capable of dispersing plant seeds (Table 2). We found 1538 seeds in total, with seeds occurring in 45% of the scat samples. The vast majority, 85%, of seeds found were Paspalum notatum and Paspalum setaceum. The third most commonly found seed came from the low- growing forb Diodia teres; this species accounted for 1.6% of all the seeds and was found in a total of seven scat samples. Few of the other seeds were notably dense or frequent in the scat. Four unknown seed types were each encountered in 2 or fewer scat samples. Germination results showed that the percent germination of digested Paspalum notatum seeds was significantly lower than that of the undigested seeds (p < 0.001 X° = 137.4 df = 1; Table 3). Only one of the 460 digested P. notatum seeds germinated, whereas 122 of 460 undigested seeds germinated. In contrast, passage through the gut of the gopher tortoise did not appear to greatly alter the germinability of the seeds of the native P. setaceum (p = 0.18 X° = 1.83 df = 1; Table 4). DiscussloN—Grasses predominated in the diet of gopher tortoises at Archbold Biological Station, in agreement with results from studies elsewhere (Garner and Landers, 1981; MacDonald and Mushinsky, 1988). Paspalum notatum was found to be frequently consumed along roadsides in this and other studies (Garner and Landers, 1981). Galactia species were the most frequently consumed forbs in MacDonald and Mushinsky’s (1988) study as well as this study, and these and other legumes were the most important forbs according to Garner and Landers (1981). Tortoises may preferentially consume these herbaceous plants because they have high nutritional value, being relatively rich sources of calcium and protein (Garner and Landers, 1981). Differences in the results of this and other studies on gopher tortoise feeding can largely be attributed to the short duration of this study compared to the year-long studies of other researchers. Though this study occurred during the season of peak activity for gopher tortoises (Douglass and Layne, 1978), annual fluctuations in IZ FLORIDA SCIENTIST [VOL. 66 TABLE 3. Germination percentages of digested and undigested Paspalum notatum seeds. Each trial consisted of all of the P. notatum seeds found in one scat as well as an equal number of undigested seeds. There was a significant difference between the percent germination of digested seeds and that of undigested seeds for all the trials combined (n = 460 p < 0.001). Percent Percent No. of Seeds Germination of Germination of Dates per Treatment Digested Seeds Undigested Seeds 7/18-9/1 200 0 18.5 7/29-9/12 100 0 52.0 7/29-9/12 100 1 13.0 7/29-9/12 60 0 333 Total: 460 0 PADD) plant species abundance and subsequent presence in the diet were not captured in this two-month study. Furthermore, this study was conducted solely along firelanes, and hence it may over-represent the food plants of tortoises that frequently feed near roads and firelanes, as opposed to tortoises that spend more time away from the road. Of the two seed species with the greatest potential to be dispersed by the tortoise (owing to their being the most commonly ingested in this study), only Paspalum setaceum, a native grass, was found to germinate after passing through the gopher tortoise gut. Paspalum notatum, or bahiagrass, is an introduced species that is now widespread throughout the southern United States. This species is adapted to heavy grazing in neotropical grasslands and has been shown to survive and even have increased germination after being digested by cattle (Gardener et al., 1993). However, after passage through gopher tortoise guts, bahiagrass seeds did not germinate. These seeds may still be viable and may in fact have been induced to dormancy by gut passage, as in a palm species ingested by box turtles in the Florida Keys (Liu et al., 2003). Digestion by vertebrates can alter germination rates and timing of plant species, with some species having accelerated and (less commonly) delayed germination (Traveset, 1998; Traveset et al., 2001). Longer experiments are needed to determine the effects of gopher tortoise digestion on bahiagrass. In contrast, Paspalum setaceum, which is native in gopher tortoise habitats, appears to be adapted to survive the rigors of tortoise digestion and germinate shortly after this passage. Germination responses among congeneric plant species to the same herbivore species often are often inconsistent (Traveset, 1998), as was the case in this study. Estimates of the home ranges and movements of Gopherus polyphemus (Auffenberg and Iverson, 1979; McRae et al., 1981; Smith et al., 1997), in combination with a 13 day average seed passage time (Bjorndal, 1987), make it possible to consider the general magnitude of the distances seeds may be moved by tortoises. McRae and others (1981) found the majority (95%) of tortoise feeding and daily activity to be within 30 meters of the burrow for most of the year. Movement between burrows is not uncommon, however, and may serve to occasionally increase the dispersal distance. A number of additional factors, such as the sex of the indi- vidual, time of year, local food resource quality (Smith et al., 1997) and the sur- rounding habitat (McRae et al., 1981) also may play a role in determining the No. 2 2003] CARLSON ET AL.—SEED DISPERSAL 153 TABLE 4. Germination percentages of digested and undigested Paspalum setaceum seeds. Each of the three trials ran for 45 days and consisted of all of the P. setaceum seeds found in one scat plus an equal number of undigested conspecifics. The difference between the total percent germination of digested and undigested P. setaceum seeds was not significant (n = 110 p = 0.18). No. of Seeds Percent Germination Percent Germination Dates per Treatment of Digested Seeds of Undigested Seeds 6/28—8/12 50 20.0 MAY 7/12-8/26 36 5.6 47.2 7/18-9/1 24 0 4,2 Total: 110 10.9 gS) distance a seed may be displaced from its parent. To date, spatial aspects of seed dispersal by gopher tortoises remain uninvestigated. It is not unusual for a local organism to spread the seeds of an exotic plant over a wide area, as is the case with some exotic Lonicera species dispersed by birds in the eastern United States (Hutchinson and Vankat, 1998). Though this mode of invasion is not always considered, especially in cases involving non-avian species, the seed dispersing capabilities of birds, mammals or reptiles could be a serious hindrance to successfully excluding certain exotics from a natural habitat. In the case of P. notatum and gopher tortoises, however, the exotic seeds do not germinate after tortoise digestion. If tortoise-dispersed bahiagrass seeds are still viable, their ger- mination appears delayed by passage through gopher tortoise guts. Effects of gopher tortoises on the demography of plants they disperse will require more study. ACKNOWLEDGMENTS—We thank Carl Weekley, Pedro Quintana-Ascencio and other members of the summer 2001 research labs at Archbold for their support and guidance early on in the project, David Matlaga for his assistance in the completion of the lab work, and Joe Yavitt, Steve Morreale, and Hong Liu for their helpful comments on earlier versions of the manuscript. This project was supported in part by Archbold Biological Station. Work on the gopher tortoise was done under Florida Fish and Wildlife Conservation Commission Special Purpose Permit # WX01402, issued to Jane Carlson. LITERATURE CITED ABRAHAMSON, W. G., A. F. JOHNSON, J. N. LAYNE, AND P. A. PERoNI. 1984. Vegetation of the Archbold Biological Station, Florida: an example of the southern Lake Wales Ridge. Florida Scient. 47: 209-250. AUFFENBERG, W. 1969. Tortoise Behavior and Survival. Rand McNally & Company, Chicago, IL. AND J. B. Iverson. 1979. Demography of terrestrial turtles. Pp. 541-569. Jn: HARLESs, M. AND H. Mortock (eds.), Turtles: Perspectives and Research. John Wiley and Sons, New York, NY. AND R. FRANZ. 1982. The status and distribution of the gopher tortoise (Gopherus polyphemus). Pp. 95-126. In: North American Tortoises: Conservation and Ecology. Wildlife Research Report 12. U.S. Fish and Wildlife Service, Washington, D.C. BJORNDAL, K. A. 1987. Digestive efficiency in a temperate herbivorous reptile, Gopherus polyphemus. Copeia 1987:714-720. BRAUN, J. AND G. R. Brooks, Jr. 1987. Box turtles (Terrapene carolina) as potential agents for seed dispersal. Amer. Midl. Nat. 117:312-318. Cox, J., D. INKLEY, AND R. Kautz. 1987. Ecology and habitat protection needs of gopher tortoise (Gopherus polyphemus) populations found on lands slated for large-scale development in Florida. 154 FLORIDA SCIENTIST [VOL. 66 Florida Game and Fresh Water Fish Commission Nongame Wildlife Program Technical Report No. 4. Tallahassee, FL. Douc ass, J. F. AND J. N. Layne. 1978. Activity and thermoregulation of the gopher tortoise (Gopherus polyphemus) in southern Florida. Herpetologica 34:359-374. GARDENER, C. J., J. G. McIvor, AND A. JANSEN. 1993. Survival of seeds of tropical grassland species subjected to bovine digestion. J. of Appl. Ecol. 30:75-85. GARNER, J. A. AND J. L. LANDERS. 1981. Food and habitat of the gopher tortoise in southwestern Georgia. Proc. Ann. Conf. Southeast. Assoc. Fish Wildl. Agencies. 35:120-134. Hayes, M. P. AND J. LECorrFr. 1989. Gopherus polyphemus (Gopher Tortoise) Food. Herpet. Rev. 20:55. HUuTCHINSON, T. F. AND J. L. VANKAT. 1998. Landscape structure and spread of the exotic shrub Lonicera maackii (Amur honeysuckle) in Southwestern Ohio forests. Amer. Midl. Nat. 139:383-390. Jackson, D. R. AND E. G. MILstrey. 1989. The fauna of gopher tortoise burrows. Pp. 86—98. Jn: DIEMER, J. E., D. R. Jackson, J. L. LANpeErsS, J. N. LAYNE, AND D. A. Woops (eds.), Proceedings of the Gopher Tortoise Relocation Symposium. Florida Game and Fresh Water Fish Commission Nongame Wildlife Program Technical Report No. 5. Tallahassee, FL. Kaczor, S. A. AND D. C. Hartnett. 1990. Gopher tortoise (Gopherus polyphemus) effects on soils and vegetation in a Florida sandhill community. Amer. Midl. Nat. 123:100-111. Liu, H., S. G. PLatt, AND C. Bora. 2003. Seed dispersal by the common box turtle (Terrepene carolina) in subtropical pine rockland of the lower Florida keys. Oecologia. In Preparation. MacDonaLp, L. A. AND H. R. MusHInsky. 1988. Foraging ecology of the gopher tortoise, Gopherus polyphemus, in a sandhill habitat. Herpetologica 44:345-—353. McRae, W. A., J. L. LANDERS, AND J. A. GARNER. 1981. Movement patterns and home range of the gopher tortoise. Amer. Midl. Nat. 106:165-179. MOLL, D. AND K. P. JANSEN. 1995. Evidence for a role in seed dispersal by two tropical herbivorous turtles. Biotropica 27:121-127. Rick, C. M. AND R. I. Bowman. 1961. Galapagos tomatoes and tortoises. Evolution 15:407-417. Rose, F. L. AND F. W. Jupp. 1982. Biology and status of Berlandier’s tortoise (Gopherus berlandieri). U.S. Fish Wildl. Res. Rep. 12:57-—70. SmiTH, R. B., D. R. BREININGER, AND V. L. LARson. 1997. Home range characteristics of radiotagged gopher tortoises on Kennedy Space Center, Florida. Chelo. Conserv. Biol. 2:358—362. TRAVESET, A. 1998. Effects of seed passage through vertebrate frugivore’s guts on germination: a review. Perspective in Plant Ecol., Evol., and Syst. 1:151-—190. , N. Riera, AND R. E. Mas. 2001. Passage through bird guts causes interspecific differences in seed germination characteristics. Functional Ecology 15:669-675. WUNDERLIN, R. P. 1998. Guide to the vascular plants of Florida. University Press of Florida, Gainesville. 806 pp. Florida Scient. 66(2): 147-154. 2003 Accepted: October 9, 2002 REVIEW Gary Mullen and Lance Durden, eds. Medical and Veterinary Entomology. Academic Press, San Diego, CA. 2002. xvi + 597 pp, clothbound, $99.95. STUDENTS of medical and veterinary entomology in the United States have been without a modern, up-to-date textbook for almost twenty years. After a nine-year gestation, Messrs. Mullen and Durden have midwifed a remarkable volume. Like many births, the labor was long and difficult, but the child all the more precious and beautiful to behold. The book is a well-organized team effort. Twenty-five contributing authors submitted chapters in their areas of expertise. Over 100 other people served as reviewers, or supplied photographs, illustrations, or literature (the Acknowledgments run almost three pages). The book begins with a short Preface, in which the editors explain how and why the book was written and the format of each chapter (there are 24 chapters). The first two are an Introduction (Chapter 1), and a discussion of Epidemiology of Vector-Borne Diseases (Chapter 2). The Introduction gives the reader suggestions for background reading, a short history of medical-veterinary entomology, and briefly presents some related areas, such as forensic entomology, contamination of foodstuffs, and phobias. This chapter has one of the most extensive bibliographies, with 242 references. The second chapter, on epidemiology, covers transmission cycles of arthropod-borne pathogens, modes of transmission, interseasonal maintenance, vector incrimination, and surveillance. Each of the remaining 22 chapters is devoted to a group of medically or veterinarily important arthropods. These chapters are organized in an identical manner: taxonomy, morphology, life history, behavior and ecology, public health importance, veterinary importance, prevention and control, and references and further reading all are taken in turn. New terms are introduced with italic type. For most chapters, the number of references given does not exceed 50. This is not due to paucity of information, but rather to the need to maintain the book at a reasonable length. With the exception of the Introduction, each chapter in this book could well merit its own volume of similar length. The chapters are presented more or less in phylogenetic order of taxonomic group discussed, beginning with Cockroaches (Chapter 3), then covering Lice (Chapter 4), and True Bugs (Chapter 5). A surprise awaits the reader at Chapter 6. Beetles are usually given short shrift in medical entomology texts. Here they receive their own fourteen-page treatment. Chapter 7 is devoted to Fleas. The next ten chapters (8 to 17) are given to a detailed treatment of flies (Diptera). Chapter 8 is a general introduction to flies and some families of minor importance are presented. Chapters 9 to 17 then cover in detail one of the major groups of medically or veterinarily important Diptera, viz., Psychodidae (Chapter 9), Ceratopogonidae (Chapter 10), Simuliidae (Chapter 11), Culicidae (Chapter 12), Tabanidae (Chapter 13), Muscidae (Chapter 14), Glossinidae (Chapter 15), Oestroidea (Chapter 16), and Hippoboscoidea (Chapter 17). Another surprise is found at Chapter 18. This chapter thoroughly discusses the Lepidoptera of medical and veterinary importance. This is 3) 156 FLORIDA SCIENTIST [VOL. 66 another group that generally receives little attention in texts. Not only are the usual urticating caterpillars included, but also there is an excellent presentation of the lachryphagous (tear-feeding) and haematophagous moths of Southeast Asia. Ants, wasps, and bees (Hymenoptera) occupy Chapter 19. Arachnids have five chapters devoted to them. Chapter 20 covers scorpions, Chapter 21 the solpugids, Chapter 22 covers spiders, Chapter 23 the mites, and Chapter 24 the ticks. This coverage of arachnid groups is unusual for a medical or veterinary entomology textbook. Treatment of arachnids comprises about 20% of the chapters and about 24% of the pages in this text. The chapter on mites is the longest of all. The book ends with taxonomic and subject indices. This book includes some truly remarkable illustrations. I counted 424, many of them in color. Particularly fascinating are photos of the lachryphagous moths. The cover illustration, a photomicrograph of the spinose ear tick, is an excellent choice. The text is free of typographic errors, and the layout, with profuse illustrations, makes for easy reading. Current topics, such as West Nile virus and Lyme disease, are included in the appropriate chapters. A wealth of information is summarized in the many tables found throughout the text. My complaints about the book are few and trivial. One photograph in chapter 19 appears to be slightly out of focus. Chapter 21, on solpugids, is only two pages long and perhaps should have been combined with the chapter on scorpions. An author index (for literature cited) would have been a nice addition to the book. The editors have produced a book that will serve not only students, but also professionals in several disciplines, indeed anyone who encounters arthropods of medical or veterinary importance in their work. Medical and Veterinary Entomology is without doubt the finest book available in English on the subject today. The last medical entomology textbook published in the United States went through seven editions and was in print for over sixty years. I am confident this new work will equal or exceed the old.—Lawrence J. Hribar, Florida Keys Mosquito Control District, Marathon, lhribar@keysmosquito.org. INSTRUCTION TO AUTHORS This information is available at two web sites: (1) IES site: http:www.chumalcas.usf.edu (click on “Centers and Institutes”, then select “Institute for En- vironmental Studies”, then select “Florida Scientist’). (2) FAS site: http://www.floridaacademyofsciences.org (select “Florida Scientist’). It is possible to search for papers and abstracts of papers for the past six years: Go the FAS site (above), select “Allen Press”. When the link is complete, select “Advanced Search” and follow the directions. 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