GULF RESEARCH REPORTS i- Published by the GULF COAST RESEARCH LABORATORY Ocean Springs, Mississippi Gulf Research Reports Volume 8 | Issue 1 January 1985 A Survey of Population Characteristics for Red Drum and Spotted Seatrout in Louisiana John M. Wakeman Louisiana Tech University Paul R. Ramsey Louisiana Tech University DOI: 10.18785/grr.0801.01 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Wakemaii; J. M. and P. R. Ramsey. 1985. A Survey of Population Characteristics for Red Drum and Spotted Seatrout in Louisiana. Gulf Research Reports 8 (l): 1-8. Retrieved from http:// aquila.usm.edu/gcr/vol8/issl / 1 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research Reports, Vol. 8, No. 1, 1-8, 1985 A SURVEY OF POPULATION CHARACTERISTICS FOR RED DRUM AND SPOTTED SEATROUT IN LOUISIANA JOHN M. WAKEMAN AND PAUL R, RAMSEY Department of Zoology, Louisiana Tech University, Ruston, Louisiana 71272 ABSTRACT Red drum and spotted seatrout stocks were sampled from seven separate study areas along the Louisiana coast and from one estuaiine area in Texas, with additional intensive temporal (monthly) and microgeogiaphic (range of salinity regimes) samplings being carried out in one Louisiana study area. Condition coeftldcnls, which did not appear to be affected by salinity regimea within the microgeogiaphic sampling area, varied significantly according to study area, with Texas fish showing significantly lower condition coefficients than Louisiana fish, Von Betulanffy growth equations were fitted and annual mortality rales were estimated to obtain preliminary estimates of yields, population numbers, and densi- ties of these species in Louisiana. INTRODUCTION The popularity of red drum, Sciaenops ocellatus (Linnaeus), and spotted seatrout, Cynoscion nebulosus (Cuvier), as game and commercial fish on the Louisiana coast has resulted in increasing tension between sports fishermen and commercial fishermen, and caused concern that populations of these species in Louisiana may be declining (Ferret et al 1980). Other Gulf coast states, facing similar controversies, have recently enacted, or are considering enactment of laws restricting or banning com- mercial fishing for these species. Assessment and effective management of such fish stocks generally requires reasonable estimates of population parameters such as natural mortality, fishing mortality, density, growUi rates, and recruitment. Length-weight rela- tionships and condition coefficients may also provide useful insights concerning the relative well-being of fish stocks in different areas (Bagenal and Tesch 1978). The primary purpose of this study was to evaluate the status of red drum and spotted seatrout populations in Louisiana, to supplement the growing body of data on the biology of these species in the northern Gulf of Mexico (Overstreet 1983a and 1983b), and to provide estimates of the various population parameters needed for more effec- tive management of these important species in Louisiana. MATERIALS AND METHODS Red drum and spotted seatrout populations were sampled from seven study areas along the Louisiana coast, and from one estuarine area in Texas. Most samples con- tained more than 40 individuals of each species. The study areas and the seasons in which they were sampled are indi- cated in Figure 1 . Louisiana study area 4 (Terrebonne Parish) was selected for more intensive temporal and microgeogiaphic sampling. For tliis purpose, four subareas within this study area were established and sampled at approximately monthly intervals Manuscript received April 30, 1985; accepted September 12, 1985. over the course of a year. The four subareas-Cocodrie, Moss Bay, Bay St. Elaine and Terrebonne Bay— are sep- arated in a north-south direction by distances of 4, 9, and 7 km* respectively, and represent different salinity regimes ranging from relatively low at Cocodrie (<10 ppt) to rela- tively liigh at Terrebonne Bay (>25 ppt). Fish were collected by both netting and angling. The majority of fish were taken in a 100-m variable mesh, monofilament gill net (stretched mesh size ranged from 2.5 to 13 cm), which was usually set in a semicircle from the shore, enclosing an area of approximately 0.1 hectares. The enclosed surface was then struck with oars to drive fish into the net. The effectiveness of such netting operations was evaluated on three occasions by blocking off the enclosed area after such “strikes" and using rotenone to ascertain the total numbers of unnetted red drum and spotted seatrout. These evaluations indicated that the netting procedures netted approximately 20% of the catchable red drum and spotted seatrout enclosed within the nets, and that the size distribution of catchable but unnetted fish was similar to that of fish taken in the variable mesh net. Although net- ting success varied widely during the course of the study, the average capture rate was close to two red drum and four spotted seatrout per set. A total of 402 red drum and 614 spotted seatrout were obtained in the entire study. Fish were sexed, weighed to the nearest gram, and their standard lengths were measured to the nearest O.l cm. To linearize the relationship between weight (W) and standard length (SL), the regression model Log W = log a -f b(log SL) was fitted to weight/length data by sex and by coastal area. Analysis of covariance was used to test for differences between regressions. Condition factors (100 W/SL^) of whole fish were calcu- lated for all fish collected, tested for normality and aver- aged according to sex, season, and coastal study area. Effects of these variables were evaluated by Duncan’s com- parison-of-means test. Similar comparisons were made among mean condition factors of fish from the four sub- areas in Terrebonne Parish to establish any temporal and/or 1 2 Wakeman and Ramsey Figure L. Sampling aieas in Louisiana and in Texas (insert) with seasons when red drum and spotted seatiout were collected from each area (SP = spring, 5 = summer, F = fall, and A = all seasons). microgeographic differences in condition factors for these species. Age and growth were evaluated by two methods: (1) by seasonal and overall length-frequency analyses; and (2) by scale reading. For the latter, plastic scale impressions were prepared from scales taken from the shoulder region of each fish and examined with a microprojcctor. Standard scale-aging criteria (Lux 1971) and published criteria for the scale-aging of sciaenids (Schlossman and Chittenden 1981) were used to identify annuli. Walford plots (Walford 1946) were fitted to obtain esti- mates of asymptotic standard length (L^) and growth coefficients (K) for red drum and spotted seatrout, Tliese estimates were then used to fit von Bcrtalanffy growth equations for these species in Louisiana, RESULTS AND DISCUSSION Weight-Length Rebitioruhtps Analysis of covariance revealed no significant differences (P>0.05) between sexes for the slope or elevation of log weight regressed against log standard length for either species (red drum, F = 1.86; spotted seatrout, F •= 2.25). For this reason, sexes were combined to obtain weight - length regression equations for Louisiana and Texas fish (Table 1). Predicted weights from the Louisiana equations for 30 cm (standard length) red drum and spotted seatrout were 509 g and 414 g, respectively, agreeing closely with Overstreet’s (1983a, b) predictions of 511 g and 409 g for Mississippi red drum and spotted seatrout. However, be- cause the majority of fish collected in tills study were between 1 and 3 years of age, caution sitould be used in applying the equations to older or younger fish. Condition Factors \ Because the condition factor of fish (K^,) is often influenced by season, sex, maturity stage, and age, such parameters are important considerations when condition factors are compared (Everhart et al. 1975). In analyzing Kj. values of fish collected in this study, the Kohnogorov- TABLE 1 Regressions of wei^t (WO in g vs. siandaxd length (SL) in cm for red drum (R) and spotted seatiout (S) collected from Louisiana and from Texas. The recession model is Log W = log a + b (log SL). N = number of fish. State Species N Log a b r^ Predicted weight fox 30 cm fl&h LA R 363 -1.4590 2.8203 .99 509 g LA S 561 -1.6664 2.8996 .98 414g TX R 36 -J.6718 2.9516 .99 488 g TX S 54 -1.5719 2.8204 .97 393 g Red Drum and Spotted Seatrout Populations 3 TABLE 2 Seasonal condition factors ±SE of ted drum and spotted seatrout. R red drum; S = spotted seatrout; N o number of fish. Species Spring (N) Summer (N) FaU (N) Winter (N) R 1.83±.02 (53) 1.99 ±.01 (217) 1.85±.01 (130) S 1.63 ±.02 (51) 1.58±.01 (269) 1.51 ±.01 (266) 1.50 ±.06 (34) Smirnov test statistic (D) was found to be Jess than the critical value of D for all collections. Thus, there was no reason to reject the hypothesis that this characteristic was distributed normally (Sokaland Rohlf 1969). Analysis of variance revealed that the values obtained in this study varied significantly with study area and with season, but not with sex. For this reason, sexes were com- bined to obtain average .seasonal condition factors (Table 2) and mean condition factors for each estuarine study area (Table 3). In both species, high condition factors appear to be associated with seasons immediately prior to spawning. Thus, red drum values were highest in summer prior to the fall spawning period, while those of spotted seatrout were highest in spring immediately preceding their spawn- ing period, which begins in late spring and continues throughout the summer. The low variability for values within each estuarine study area (Table 3) suggests that condition factors may be useful in comparing the relative well-being of subpopula- tions of these species, provided that the fish from each area are collected during the same season. Duncan’s multiple range test indicated that red drum and spotted seatrout from the Port Aransas area of Texas (collected during sum- mer 1983) were significantly (p<0.05) less robust than Louisiana fish collected during the same season (Table 3). Analysis of condition factors of fish from coastal study area 4 revealed no significant differences between the four subareas sampled, indicating that the salinity regimes (low, <10 ppt; intermediate, 10-25 ppt; and high, >25 ppt) represented within this microgeograpldc range have little effect on the robustness of these euryhaline species. Condition factors for both species from study area 4 did. TABLE 3 Regional condition factors ±SE of ted drum and spotted seatrout fiom Louisiana study areas 2-7 and from Texas. Study Area Red Drum Spotted Seatrout N K, N Kc L2 (56) 2.05 ±.02 (64) 1.71 ±.02 L3 (49) 1.96 ±.02 (50) 1.35 ±.02 L4 (100) 1.94±.02 (296) 1.53±.01 L5 (43) 1.94 ±.02 (51) 1.49 ±.02 L6 (55) 2.04 ±.02 (54) 1.57±.0I L7 (11) 1.93±.04 (SI) 1.61 ±. 01 Texas (37) 1.82 ±.02 (55) 1,41 ±.02 however, vary significantly with season, following the same seasonal trends shown in Table 2. Length Ftequencies, Age and Growth Standard -length distribution (2-cm intervals) of all Louisiana red drum and spotted seatrout collected in this study are shown in Figure 2. Modes could be discerned in red drum length frequencies at 22 cm, 32 cm, 44 cm, and 56 cm. Comparison with other age-length information for red drum (Pearson 1929, Matlock 1984) indicates that these modes probably represent age classes I, II, 111, and IV, respectively. As might be expected in a species with an extended spawning period, age classes were not so clearly evident in length distributions of spotted seatrout. Nevertheless, apparent modes could be discerned at 10 cm, 26 cm, 34 em, and 44 cm. Based on age-length data for spotted seatrout from the Gulf coast (Guest and Gunter 1958) and from the eastern U.S. coast (Mercer 1984), the latter three modes probably represent age classes 11, III, and IV, respectively. It should be noted, however, that Pearson’s (1929) back- calculated age-lengths for spotted seatrout indicate a slower growth rate than is indicated here, and if his estimates were followed these modes would more likely represent classes III through V. Length frequencies during each season were also deter- mined, and modes from these seasonal distributions were STAMDARD LENGTH (cm) Figure 2. Length distribution of all Louisiaiu red drum and spotted seatrout collected in this study. Roman numerals indicate probable age class modes. 4 Wakeman and Ramsey graphed to provide an indication of growth of each species during their first three years (Figure 3). The plots indicate red drum standard lengtlis to be 22 cm at age 1 and 38.5 cm at age 2, while the indicated standard lengths of spotted seatrout at these ages are 17,5 cm and 30 cm, respectively. The curvilinearity of the growth curves in Figure 3 suggests decreased growth rates in both species during winter Aging by scale analysis was hampered in both species by the presence of false annuli wliich were often difficult to distinguish from true annuh. Reading of red dnim scales was further hindered by calcified deposits wliich tend to obliterate annuli as the fish grow. The consistency of our age determinations by scale reading was evaluated by ran- domly selecting 50 scale impressions of each species for re- examination. The second reading showed 76% agreement with the first reading for spotted seatrout, but only 32% for red drum. SPRING SUMMER FALL WINTER Figure 3. Yearly growth of red drum and spotted seatrout during their first three years as estimated from changes in seasonal length distribution modes. Closed circles indicate seasonal length distribu- tion modes and dashed curves represent extrapolations of tines con- necting the seasonal modes. Yeariy increments from the y-intercept are represented by X. Despite these inconsistencies, the mean lengths of each age class (as determined by number of annuli identified) were similar to the modal age-class lengths identified from length-frequency analysis (Table 4). Thus, scales can appar- ently be used to age spotted seatrout and red drum from Louisiana populations, but the procedure is difficult and time consuming. Figure 4 shows Walford plots fitted to the year-end standard lengths for each species. The Walford equations for these plots are: red drum: SL^^j = 22 + 0.75 SL^ spotted seatrout: = 17.5 + 0.71 SL^ where SL^ and are standard lengths at ages t and t+l, respectively. Because the Walford plots are based on only two points, they should be used with caution. More- over, growth of these species is probably not isometric over larger size ranges, so asymptotic weights estimated from these equations (Table 5) ace probably underestimates. By comparison, Condrey et al. (1984) estimated an asymptotic length of 65.5 cm for Gulf coast spotted seatrout, while Figure 4. Watford’s growth transformation for Louisiana red drum and spotted seatrout showing predicted asymptotic standard length (Lqo) for each species. Year-end standard lengths were obtained from Figure 3. TABLE 4 Standard lengths (cm) of various age classes of red drum and spotted seatrout. MODAL LENGTH represents modes from standard length distributions in Figure 4. MEAN LENGTH (ANNULI) represents means of age groups identified by scale analysis. Estimated yeu-end lengths are from Figure 3. Spotted Seatrout Red Drum AGE CLASS I 11 HI TV I II III IV MODAL LENGTH _ 26.0 34.0 44.0 22.0 32.0 44.0 56.0 MEAN LENGTH (ANNULI) 16.0 23.0 30.0 36.0 21.0 29.0 44.0 57.0 EST. YEAR-END LENGTH 17.5 30.0 - 22.0 38.5 - Red Drum and Spotted Seatrout Populations 5 TABLE 5 Von BerlaUnffy equations for growth in length of red drum and spotted seatiout. Standard lengths (SL) in cm were derived from the von Bertalanffy equations with assumed to be ^ero. Estimated weights were calculated from Louisiana weight-length regressions in Table 1*0^ = instantaneous growth coefficients. Red Drum Spotted Seatrout Equation: It = 88,0 (l-^5-2fiT7(t+to)) It = 61.2 (i_e-3864(t’to>) SL(cm) W(g) Gx SL{cm) W(g) Gx SL and W at age 1 22 210 17.5 87 SL and W at age 2 38.5 1026 1.582 30.0 414 1.559 SL and W at age 3 50.9 2261 .790 38.9 879 0.753 SL and W at age 4 60.2 3635 .475 45.3 1366 0.441 SL and W at age 5 67.2 4941 .307 49.8 1798 0.275 Asymptotic SL & W 88.0 10593 61.3 3285 Matlock (1984) estimated an asymptotic length of 106.5 cm for Texas red drum. Despite some ongoing criticisms of its suitability (Knight 1968, Schnule 1981), the von Bertalanffy growth equation is still widely used in fisheries research, and its parameters are commonly implemented in yield-pei-recruit analysis. For this reason, von Bertalanffy equations for growth in length were estimated from the Walford plots and tenta- tively used to project standard lengths for each species for ages 1 througli 5 (Table 5). Predicted weiglits in Table 5 were obtained from the length-weiglu regressions for each species. Yearly growth rates (G^) were calculated from the pre- dicted year-end weight of each age group. The equation for yearly growth rate is: G^=(lnWj-lnWi^l)/l where Wj is weiglit in grams at age i and t is time in years (Bagenal and Tesch 1978). Yearly values for each spe- cies decreased with Increased age (Table 5) following the usual pattern for growth in fishes (Paloheimo and Dickie 1966), The G^ values indicate that red drum and spotted seatrout in Louisiana both show rapid growth rates, particu- larly during their first two years when average daily weight increases are close to 0,4% of body weight. Sex Ratios and Mortality Rates Analysis of sex ratios of various age classes (t-test, a = 0.05) showed that red drum sex ratios did not differ signi- ficantly from 50:50 over the entire length range collected (16-85 cm, SL). However, as standard length of spotted seatrout increased, there was a marked increase in the proportion of females (Figure 5). No male seatrout over 40 cm SL were collected. Similar increases in the propor- tion of females with increased size have been previously noted in Mississippi (Overstreet 1983a) and Florida (Tabb 1961) populations of spotted seatrout. Annual mortality rates of these species can be estimated from the age frequency data if the following assumptions are made (Rounsefell and Everhart 1953): (1) ages have been accurately deciphered; (2) natural and fishing mortal- ity rates were uniform and constant during the time period covered by all age groups collected; (3) annual recruitment was constant over the time period represented by the sample; and (4) the age distribution of samples are repre- sentative of the true age distribution. Although these assumptions could not be established with any degree of certainty, age frequencies from this study were used for preliminary estimations of total mortal- ity for Louisiana populations of red drum and spotted sea- trout. The method of Robson and Chapman (1961) was used to obtain estimates of the annual survival rate (s) and the instantaneous mortality coefficient (Z) for each species (Table 6). If male and female seatrout are considered sep- arately, the estimated annual survival rate of female spotted seatrout (0,36) is approximately double that of males (0.16), a phenomenon which may have an important influ- ence on the fishery. The estimated annual survival rate for red drum was also 0.16. Previous estimates of survival rates of these species tend to be somewhat higher than those obtained in this study. Tatum (1980) estimated annual sur- vival for spotted seatrout populations in Alabama to be as high as 0.50, while Rutherford (1982) estimated an annual STANDARD LENGTH MIDPOINTS ICMl Figure 5. Changes in sex ratios of spotted seatrout with respect to body length. 6 Wakeman and Ramsey TABLE 6 Annual survival rate (s) and instantaneous mortality coefficient (Z) for spotted seatrout and red drum as estimated from collected age frequencies. Postulated instantaneous fishing mortality coefficients (F) and instantaneous natural mortality coefficients (M) are based on the assumption that fishing mortality is 90% of total mortality (see text). Species s Z F M Spotted seatrout 0.32 1.139 1.025 0.11.4 Red dtUm 0.16 1.833 1.650 0.183 survival rate of about 0.25-0.30 for spotted seatrout in Everglades National Park. Matlock (1984) indicates an an- nual survival rate of 0.20 for 7‘exas red drum populations. We were unable to obtain estimates of fishing mortality rates versus natural mortality rales from our data. Natural mortality, however, tends to be relatively low' in heavily exploited fish species, with fishing mortality usually com- prising 85-90% of total mortality after such fishes attain vulnerable age (Rounsefell and Everhart 1 953). Pauly’s (1980) analysis of interrclationsliips between natural mor- tality, growth, and mean environmental temperature in 175 fish stocks also indicates that, for rapidly growing, long- lived species at temperatures characteristic of the Louisiana coast, natural mortality mi^t be expected to be relatively low compared with fishing mortality. For this reason, the postulated instantaneous coefficients for fishing mortality (F) and natural mortality (M) of red drum and spotted sea- trout in Louisiana (Table 6) are based on the assumption that mortality due to fishing is approximately 90% of total mortality in these species. Population Numbers and Densities If an estimate of the annual catch (C) is available, the annual fishing mortality rate (f) can be used to obtain an estimate of the total number of fish of vulnerable size in a population. The appropriate equation isN = C/f, where our postulated value for f is 0.9 (1-s). Approximately 450 thousand kg of red drum and 600 tliousand kg of spotted seatrout are taken annually from Louisiana waters by commercial fishermen (Adkins et al. 1979, Ferret et al. 1980). Since the recreational /commercial fishing ratio for both species has been estimated to be about 90:1 (Adkins el ai. 1979), the total yearly harvest in Loui- siana is about 40 million kg of red drum and about 55 mil- lion kg of spotted seatrout. Dividing these biomass values by the mass of the average fish taken in this study, we ob- tained the following estimates of total catch (C) for each species: red drum; C = 40 million kg/0.525 kg = 76 million spotted seatrout: C = 55 million kg/0.385 kg = 143 million. Inserting these values into the equation, N = C/f, the following preliminary estimates of total number of fish of vulnerable age in Louisiana waters were obtained: red drum: N = 76 million/0.756 = 100.5 million spotted seatrout: N = 143 million/0.612 = 233.7 million. It is important to note that these population estimates are conservative since they are based on the assumption that fishing mortality is relatively high compared to natural mortality for these species in Louisiana. If fishing mortality is low for these species, as was suggested by Iversen and Moffet (1962), population estimates would be almost an order of magnitude gre^iter. Barrclt (1970) calculated the total water area of coastal Louisiana to be J .376 million hectares. Thus, the expected average densities based on our preliminary estimates of population numbers in Louisiana are : red drum: 100.5/1.376 = 73.5 individuals per hectare, and spotted seatrout: 233.7/1.376 = 169.8 individuals per hectare. A 100-m net, such as was used to collect fish in this study, encloses an area of approximately 0.1 hectare when set in a semicircle from the shore. If many such sets are made, the average number of fish enclosed in each set should include about 7 red drum and about 17 spotted seatrout- Because our rotenonc studies indicated that this netting procedure captures approximately 20% of the vulnerable-sized fish enclosed, an average set should capture 1.5 red drum and 3.4 spotted seatrout. These estimates are very close to our overall stratified sampling capture averages Figure 6. Yield curves (with = 1,2, and 3) aa a function of F for red drum (top) and spotted seatrout (bottom). The closed squares indicate the cunent estimated position of the Louidana fishery and the open squares indicate the estimated position if standard length at first capture were set at 30 cm. Red Drum and Spotted Seatrout Populations 7 from many sets at many diverse locations throughout the coastal region of Lxjuisianaj an observation which tends to support our population estimates for these species. Yield per-Recruit Estimates Beverion and Holt's (1966) tables of yield functions pro^ vide isopleths of yield per recruit as a function of size at first capture and exploitation rale for a series of values of M/K ranging from 0.25 to 5.0. Using the estimated M/K values from the present study (M/K - 0.35 for spotted seatrout; M/K = 0.64 for red drum), and assuming the size at first capture to be 20 cm (no minimum recreational size limits for either species in Louisiana), ihe tables indicate yields of about 0,4 kg/recruit for red drum and about 0.3 kg/recruit for spotted seatrout when the exploitation rate is 0.9. The Beveiton-Holt (1966) model is particularly useful for assessing effects of changes in fishing effort or in size of first capture (GuUand 1969). The effect of increasing the size of first capture is graphically illustrated in Figure 6 in which yield-per-recruit curves as a function of the fishing mortality coefficient (F) are shown for various ages at first capture (1^.). The curves iiidicate that yield per recruit for red drum and spotted seatroul in Louisiana would be al- most doubled by increasing the length at first capture to 30 cm (SL). By contrast, if the recreational/commercial fishing ratio for these species is about 90:1 (Adkins et al. 1979), a ban on commercial fislung would have minimal effects on yield per recruit. ACKNOWLEDGM ENjS TMs study was conducted under contract (82'LAT/03l- B51) from the Louisiana Board of Regents Research and Development Program. Assistance from numerous members of the Louisiana Department of Wildlife and Fisheries, Sea- food and Fish Division, is gratefully acknowledged. Nancy Brown, University of Texas Marine Sciences Institute, pro- vided valuable assistance in the collection of Texas samples. Material support for the intensive sampling in Terrebonne Parish was provided by the Louisiana Universities Marine Consortium at Cocodrie. Student research assistants, Donald Maum and Mark Mayes, aided in the collection of fishes. REFERENCES CITED Adkins, G., J. Tarver, P. Bowman, & B. Savoie. 1979. A study of the commercial finfish in coastal Louisiana. Lou/s/am Dept, of Wild- life and Fisheries, Tech. Bull. No. 29. 87 pp. Bagenal, T. B. & F, W. Tesch. 1978. Age and growrh. Pages 101- 136 in: T. Bagenal (ed,), Methods for Assessment of Fish Pro- duction in Fresh Waters. IBP Handbook. No. 3, Blackwell Scien- tific Publishers, London. 36.5 pp. Barrett, B. 1970. Water measurements of coastal Louisiana. Louisi- ana WildHfc and Fisheries Commission, New Orleans. 196 pp. Dcverion, R. J. & S. J. Holt. 1966. Manual of methods for Hsli stock assessments. Part 11. Tables of yield functions. FAO Fisheries Technical Paper. No. 38. 67 pp. Condrey, R. E., G. Adkins, & M. W. Wascom. 1984. A yield-per- recruit analysis of spotted seatrout. Iti-House CEFJ Fisheries Report No. 84-6. Louisiana State University Coastal Ecology and Fisheries Institute. J 7 pp, Everhart, W. H., A. W. Eipper, & W. D. Youngs. 1975. Principles of Fishery Science. Cornell University Press Ltd,, London. 288 pp. Guest, W. C. & G. Gunter, 1958. The seatrout or weakfishes (Genus Cynoscion) of the Gulf of Mexico. Gulf States Marine Fisheries Commission. Technical Si4mmary, .\o. 1 . 40 pp. GuUand, 5. A. 1969. Manual of methods for fish stock assessment; Pan 1. Fish population analysis. FAO Manuals in Fishery Science. No. 4, 154 pp. Iversen, E- S. & A. W. Moffei, 1962. Estimation of abundance and mortality of a spotted seatrout population. Trans. Am. Fish. Soc. 91:395-398. Knight, W. 1968. Asymptotic growth: an example of nonsense dis- guised as mathematics./. Fish. Res. Board Can, 25:1303-1 307. Lu,x, F. E. 1971 - Age determination of fishes (Revised). U.S. Depart- ment of Commerce, Fishery Leaflet 637. 7 pp. Matlock, G. C. 1984. A basis for the development of a management plan for red drum in Texas, Ph.D. dissertation, Texas A&M Uni- versity. 255 pp, Mercer, L. P, 1984. A biological and fisheries profile of spotted sea- trout, Cynoscion nebulosus. North Carolina Department of Natural Resources, Special Scientific Report, No. 40. 87 pp. OveisUcet, R. M. 1983a. Aspects of the biology of the spotted sea- Uout, Cynoscion nebulosus, in Mississippi. Gulf Res. Rept.. Supplement 1 ;l - 43. . 1983b. Aspects of the biology of the red dium, Sciaenops ocelkta. in Mississippi. Gulf Res. Rept.. Supplement 1:45-68. PaLoheimo, T. E. & L. M. Dickie. 1966. Food and growth of fishes. III. Relations among food, body size, and growth efficiency. /. Fish. Res. Board Qjn. 23; 1209-1 248. Pauly, D. 1980. On the interrelationships between natural mortality, growth parameters, and mean environmental temperature in 175 fish stocks./. C’ons. /nr. 'Explor. Mer 39:175-192. Pearson, J. C. 1929. Natural history and conservation of the redfish and other commercial sdacnids on the Texas coast. Bull. U.S. Bur. Fish. 64:178-194. Perretl, W. S., J. E. Weaver, R. D. Williams. P. L. Johansen, T. D. Mcilwain, R. C. Raulcrson, &. W. M. Tatum. 1980. Fishery Pro- files of Red Drum and Spotted Seatrout. Gulf Slates Marine Fisheries Commission, Publication No. 6. 60 pp. Robson, D. S. & D. G, Chapman, 1961. Catch curves and mortality rates. J>ans. Am. Fish. Soc. 93:215-226. RounsefelL G. A. & W. H. Everhart. 1953. Fishery Science: Its Methods and Applications. John Wiley and Sons, Inc., N.Y. 444 pp. Rutherford, E. S, 1982. Age, growth and mortality of spotted sea- trout, Cynoscion nebulosus, in Everglades National Park. Florida. M.S. thesis, University of Miami, Coral Gables. 65 pp. Schlossman. P. A. & M. E. Chittenden, Jt. 1981. Reproduction, movements, and population dynamics of ihe sand seatrout, cynoscion arenarius. Fish. Bull. 79(4):649-669. Schnute, I. 1981. A versatile growth model with statistically stable parameters. Can. J. Fish. Aquat. Scl 38:1!) 28-1140. Sokal, R. R. & F. J. Rohlf. 1969. Biometry. W. H. Freeman, San I fancisco. 776 pp. Tabb, D, 1961- A contribution to the biology of the spotted sea- trout. Cynoscion nebulosus (Cuvier) of east-central Florida. Fla. 8 Wakeman and Ramsey Dep. Nai. Resour. Mar. Res, Lab. Tech, Ser. 35:1-24, Tatum, W, M. 1980. Spotted scatrout (Cynoscion nebulosus) age and growth: data from annual fishing tournaments in coastal Alabama, 1964— 1977, Proceedings of colloquium on biology and management of red drum and seatiout. Gulf Coast Marine Fisheries Commission, Special Report, No. 5:89-92. Walford, L. A. 1946. A new graphic method of describing the growth of animals. Bull. 90(2): 141 -147. Gulf Research Reports Volume 8 | Issue 1 January 1985 Soil Characteristics of Four Juncus roemerianus Populations in Mississippi Lionel N. Eleuterius Gulf Coast Research Laboratory John D. Caldwell Gulf Coast Research Laboratory DOI: 10.18785/grr.0801.02 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Eleuterius, L. N. andj. D. Caldwell. 1985. Soil Characteristics of Four Juncus roemerianus Populations in Mississippi. Gulf Research Reports 8(1): 9-13. Retrieved from http://aquila.usm.edu/gcr/vol8 /issl/2 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research Reports, Vol. 8, No. 1,9-13* 1985 SOIL CHARACTERISTICS OF FOUR JUNCUS ROEMERIANUS POPULATIONS IN MISSISSIPPI LIONEL N. ELEUTERIUS AND JOHN D. CALDWELL Botany Section. Gulf Coast Research Laboratory, Ocean Springs. Mississippi 39564 ABSTRACT The physical and chemical characteristics of soil from four widely separated Juncus roemeriams populations in Mississippi tidal marshes are determined. Tlie 7. roemerianus populations studied are located in Grand Bayou, Salt Flats, Weeks Bayou, and Belle Fontaine marshes. Organic matter, pH, CEC, N, P. K, Ca, S, Mg, and Zn analyses are based on composite soil samples. The percentage of sand, silt, and day of the marsh soib is determined along with soil water content from the four locations. Statistical analysis indicates which marshes are different for eadi soil characteristic tested. No appreciable amounts of organic matter arc present in the soils from Grand Bayou and the Salt Flats, however, the soils of Weeks Bayou and Belle I’ontainc marsh are highly organic. Magnesium is signiHcantiy different among all locations. Concen- trations of P are greatest In the marsh soils from Grand Bayou and lowest in the Salt Flats. Greater values arc recorded for organic matter, CEC, N, K, Ca, S, Mg, and Zn in the Weeks Bayou and Belle Fontaine marsh Soils than are recorded for the soils at Grand Bayou and Salt Flats.The results of the soil analyses show that tidal marsh soils vary considerably in physical and chemical characteristics among locations, and J. roemerianus is able to grow well in a variety of soil types. INTRODUCTION Tidal marshes in Mississippi form a thin border between the uplands and the Mississippi Sound. The marshes in Mississippi have been described by Eleuterius (1972) and Eleuterius and McDaniel (1978). These marshlands are dominated by the black needlerush Juncus roemerianus Scheele. Tidal marsh soils along the Gulf Coast appear to be very diverse. Chabrcck (1972) reported on the diversity of the vegetation, water, and soil characteristics of Louisiana marshlands. DeLaunc ct al. (1981) and Bmpbacher et al. (1973) also reported on the chemical properties of marsh soils in Louisiana. The tidal marsh soils of the Florida Gulf Coast have been studied extensively by Coultas (1978a, 1978b) and Coultas and Gross (1975, 1977). The relationships between the soils and the plant com- munities of Louisiana marshes have been studied by Palmisano and Chabrcck (1972). They related chemical variables of the marsh soils with the distributions of major plant species in Louisiana. DeLaune et al. (1979) evaluated the relationship between soil properties and the biomass of Spartina altemiflora. The objective of the present research is to compare soil characteristics from four populations of J. roemerianus located at widely separated locations along the Mississippi Coast and to determine the similarities and differences in the soils occupied by /. roemerianus. MATERIALS AND METHODS Composite soil samples were collected from four popula- tions of J. roemerianus. Locations of the Grand Bayou, Salt Flats, Weeks Bayou and Belle Fontaine populations of J. roemerianus are shown on Figure I. The soil samples were Manuscript received June 25, 1984;accepted December 10, 1984. taken from the upper 5 to 15 cm of substrate and placed in plastic bags. Samples were frozen until the individual tests were performed. Soil water content, which is expressed as the ratio of the mass of water present in the sample to the mass of the dry sample and presented as a percent (Black 1965a), was obtained by oven drying the soil samples in seamless 180 ml cans at 105'^C until dry. The marsh soils were analyzed by using standard methods (Black 1965b). Determinations were made of pH, cation-exchange capacity (CEC), organic matter, total nitrogen (N), acid-extractable phosphorus (?), potassium (K), calcium (Ca), sulfur (S), magnesium (Mg), and zinc (Zn). Individual chemical proper- ties were compared among the four populations by analysis of variance (ANOVA) to determine statistical differences among the populations. The chemical properties which showed a significant difference were then subjected to Duncan’s multiple range test, which indicated the popula- tion or populations that were statistically different, based on soil properties, from the other populations. The per- centage of sand, silt, and clay contained in the soil was analyzed by granular metric methods, in which the sand values were obtained by sieving and the silt and clay values were obtained by hydrometer. These latter analyses were conducted by the Geology Section of the Gulf Coast Research Laboratory. RESULTS Soil physical characteristics obtained from the four loca- tions dominated by /. roemerianus are shown in Table 1. Based on the percentage of soil water from the different locations, it can be shown that the retention of water by the soils from Weeks Bayou and Belle Fontaine is greater than that by the soils from the Salt Flats and Grand Bayou marshes. No measurable amounts of organic matter are found in the soil samples taken from Grand Bayou and the 9 10 Eleuterius AND Caldwell Eiguie 1. Locations of the foui Simeus roemerionus populations studied axe indicated by the arrows and names of the sites. Salt Flats, but the organic matter in both the Weeks Bayou (x = 21 . 2 %) and Belle Fontaine (x = 24.1%) soils is an important feature. The percent sand values show the Salt Flats soil has the greatest sand content and differs from all other locations. The Grand Bayou marsh soil, which is also high in sand content, also differs from the other locations. However, the relatively low sand values from Weeks Bayou and Belle Fontaine marshes do not show a difference. The silt and clay values, which are greater in the Weeks Bayou and Belle Fontaine marshes, do not differ. However, a difference occurs between these marshes and both the Salt TABLE 1 Soil physical charactetisticsfjttm low Juncus roemeTianus locations. Mean values for percent soil water from two replicates. Mean values for the percent organic matter, .sand, silt, and clay from six replicates. The organic matter values are the mean percentages for the total soil weight retained in the sieve series. Values in horizontal rows followed by the same capital tetter are not significantly different (Or = 0.05) according to Duncan’s multiple range test. Soil Physical Characteristics Grand Bayou Marsh Salt Flats Marsh Weeks Bayou Marsh Belle Fontaine Marsh *^(3,20) Organic Matter (%) 0.0 A 0,0 A 21-2 B 24.1 B 6.59t Sand (%) 71.1 A 82.8 B 3.3 C 4.0 C 557.55t Silt {%) 18.1 A 13.1 A 41.3B 42,1 B 7,59t Clay (%> 10.8 A 4.1 A 34.2 B 29.8 B 31.93t Soil Water (%) 29.2 19.4 143.9 123.3 f Significant at the 0.05 level. Flats and Grand Bayou marshes, which are not different. The salinity of the soil water fluctuates frequently at these locations depending on the season, temperature, tidal pattern, and amount of precipitation (Eleuterius 1974). Soil water salinities are frequently observed as high as 300 ppt on the Salt Flats, but salinity values for soil water at the other three locations rarely exceeds 20 ppt. Tire results of the Duncan’s multiple range test on S, Ca, K, P, and pH do not show a difference between the Weeks Bayou and Belle Fontaine marshes; however, all the other combinations of marsli locations are different for these soil analyses (Table 2). The Grand Bayou and Salt Flats marshes are not different from each other and Weeks Bayou is not different from Belle Fontaine for Zn. Magnesium is differ- ent for all four locations. Organic matter, CEC, and N are not different for the Salt Flats and Grand Bayou marshes, however, all other combinations of marsh locations are different. Although the values obtained from the soil chemical analyses vary greatly among the four locations, the Weeks Bayou and the Belle Fontaine marsh soils have greater con- centrations of N, K, Ca, S, Mg, and Zn, and greater amounts of CEC and organic matter than are found in the marsh soils at Grand Bayou and the Sail Flats. The soils are more acidic in the marshes at Weeks Bayou and Belle Fontaine than those in the other two locations. However, the P con- centration is greater in the soils from Grand Bayou than the other three locations. The Salt Flats soils have the lowest concentrations of P, and those at Weeks Bayou and Belle Fontaine are approximately the same. Soils of Juncus Populations 11 TABLE 2 Soil characlemticii from four locations dotninated by Juncus roemerianus. Values are the mean and standard deviation of three replicates. Values in horizontal rows followed by the same capital letter axe not significantly different (a= O.OS) according to Duncan's multiple range test. Rahge values axe in parenthesis. Locations Soil Analyses Gnnd Bayou Maxsh Salt Flats Marsh Weeks Bayou Marsh Belle Fontaine Maxsh pH 7,5 ±0.05 A 6.8±0.17 B 6.1+0.15 C 6.3+0.10 C 75.78t (7.5 -7.6) (6.6-6.9) (5.9-6.2) (6.2-6.4) Cation-Exchange Capacity (mcq/IOOg) 5.45±0.15 A 2.91+0.10 A 28.91+2.60 B 25.46+1.21 C 259.561 Organic Maltci (%) 0.58±0.13 A O.OOtO.OO A 18.8810.36 B 17.1211.03 C 1025.60t Total Nitrogen (ppm) 433.0143.5 A 211. 0+10.0 A 5107.0+298.1 B 7277.31392.8 C 600.75t Phosphorus (ppm) 44.013.4 A 4.0+0.0 B 26.315.1 C 26.011.7 C 77.87t Potassium (ppm) 27B.014LI A 145.0 + 7.5 B 529.0+51.3 C 482.0130.8 C 72.19t Calcium (ppm) 202.0 ±0.0 A 78.7 + 18.4 B 1355.3+70.7 C 1266.0+69.6 C 541.53t Sulfur (ppm) 146-0119.0 A 61.7+4.0 B 300.0 1 0.0 C 300.0+0.0 C 443.271 Magnesium (ppm) 412.7+10.5 A 241.0+ 1.7 B 2327.31 67.6 C 2098.7+95.2 D 1045. 08t Zinc (ppm) 0.6310.05 A 0.43+0.25 A 2.67+0.58 B 2.30+0.79 B 14.96t tSignificant at the 0.05 level. DISCUSSION In comparison to the marshlands located elsewhere along the northern Gulf of Mexico, no extensive, detailed studies have been conducted on the tidal marsh soils in Mississippi. However, the marsh soils along the Gulf Coast are shown to be very diverse in physical and chemical properties by com- paring the works of Chabreck (1972), Patrick et al. (1977), DeLaune et ai. (1979), DeLaune et al.(198l) in Louisiana, and Coultas (1978a) in Florida. Although differences in the salt marsh vegetation have also been reported in the marshes of the northern Gulf of Mexico by Palmisano and Chabreck (1972) in Louisiana and Eleuterius (1972) in Mississippi, no clear relation to soil type was noted. Water retention by soils depends largely on their physical structure. Tidal marsh soils that have a hi^ sand content are more likely to lose soil water rapidly when exposed by low tides, than soils with a high organic content. Therefore, the structure, density, and other physical aspects of tidal marsh soils are important to all water relationships of plant species that grow in them. The soil characteristics reported in this study show that the marsh soils vary among the four locations; however, some similarities in the soils are also indicated. Soil pH values ranged from S.9 to 7.6 for the four locations. These values are typical for tidal marsh soils and the range of our values corresponds to those reported by Chabreck (1972) for soil pH in saline marsh where J. roemerianus occurs in Louisiana. Boyd (1970) showed that the concentrations of nitrogen and sulfur were directly related to the amount of organic matter found in aquatic soils. Tliis relationship is also evident in our data. The greater concentrations of N and S found in the marsh soils of Weeks Bayou and Belle Fontaine correspond to greater organic matter content in the soils at the same locations. Boyd (1970) and Coultas and Gross (1975) stated that cation-exchange capacity of tidal marsh soils increases correspondingly with an increase in organic matter content. The higher the cation-exchange capacity of a soil, the greater the ability of the soil for trapping cations. Thus, cation -exchange capacity of tidal marsh soils varies directly with organic content (Boyd 1970, Coultas 1978a). This direct relationship between cation-exchange capacity and organic matter is clearly shcvwn in our data. The Grand Bayou and the Salt Flats soils are low in organic matter and these soils also have correspondingly lower cation-exchange capacity values than the higher organic soils of Weeks Bayou and Belle Fontaine, Farwell et al. (1979) also showed that sulfur compounds volatilized from soils at dif- ferent moisture contents. Such volatilization obviously oc- curs in tidal marsh soils in Mississippi. Smith and DeLaune (1983) reported gaseous loss of nitrogen from Louisiana marshes, George and Antoine (1982) showed that tempera- tures, soil pH, and substrate concentrations affect denitrifi- cation. Brupbacher et al. (1973) reported large variations in the amounts of the elements magnesium, calcium, and potas- sium in the soils from the marshlands of Louisiana. The results from our data also show a wide range for these ele- ments wliich varied as follows; Mg, 241 to 2327 ppm; Ca, 78 to 1355 ppm; K, 145 to 529 ppm These fluctuations depend in part on daily and seasonal tidal levels, rainfall, and temperature. Variations of soil phosphorus in marshlands have been shown by Brupbacher et al. (1973), Palmisano (1970) and Palmisano and Chabreck (1972) have reported that lower phosphorus concentrations are associated with greater amounts of organic matter in the soil. Phosphorus is found 12 Eleuterius and Caldwell in variable concentrations at the different marshes in the present study. The greatest P concentrations are found in the soils at Grand Bayou, which are low in organic matter con- tent. However, Weeks Bayou -and Belle Fontaine marshes, which are high in organic matter content, have lower P concentrations than the Grand Bayou marsh. The reason for the low P concentrations found in the soils at the Salt Flats, which are also very low in organic matter, is not clear. Zinc concentrations in marsh soils at the mouths of several rivers along the Atlantic Coast, which are dominated by S. alterniflora, have been reported by Dunstan and Windom (1975). They reported zinc concentrations in the sediments that ranged from 14.9 to 69.6 ppm. However, the 2n concentrations reported in the present study are considerably lower (0.43 to 2.67 ppm). The reason for the considerable differences in the amount of 2n between loca- tions on the Mississippi Gulf Coast and those on the Atlantic Coast is not known. DeLaune et al. (1981 ) have shown that plant nutrients and heavy metals accumulate in salt marshes through Sedimentation and accretion. However, Patrick et al. (1977) showed that redox affected nutrient availabil- ity in coastal wetlands. They found that although certain plant nutrients are present m marsh sods, their availability to certain marsh plants may be restricted. Waisel (1972) has pointed out that the nutrient uptake mechanism varies among halophytes. Eleuterius and Caldwell (1981) have shown that the absence of K, S, P, and Mg caused severe growth retardation and was essential to the growth of J. roemerinnus. The absence of Ca, N, and Fe had a less severe effect on growth, indicating that J. roemerianus is physio- logically peculiar. J, roemerianus may have a completely different physiological mechanism for uptake and utiliza- tion of nitrogen in comparison to what is presently known for most halophytes and terrestrial plants. It was not our purpose to compare nutrient concentration with plant growth or production. However, Valiela and Teal (1974) indicated that nitrogen availability was the most limiting and regulating factor in plant production on tidal wetlands. Patrick and DeLaune (1976) showed the pattern of nitro- gen and phosphorus utilization by S, altemijlora. Their work indicated that nitrogen was the most important nutrient hmiting the growth of the grass 5. alterniflora. A similar relationship for the rush J. roemerianus has not been established. Furthermore, Smith and DeLaune (1984) and Mendelssohn (1982) indicated that the rhizosphere and “deposits” found on the roots o( S. alterniflora were related to the nutrition of the plant. They indicated that the area immediately around the root had different nutrient concentrations than the surrounding soil. “Deposits” on the roots were also found to have different concentrations of nutrients than the surrounding soil. No such "deposits” are found on the roots of / roemerianus. Our study shows that / roemerianus is able to grow in a variety of marsh habitats that have different chemical and physical soil properties. Extensive monotypic and almost pure stands of / roemerianus are fonned over a wide range of soil types. In other local marsh areas / roemerianus grows intermixed with other plant species. The reason for exclusion of other species from some populations is not known. The soils in the areas studied range from sand and clay, which are relativelylow in organic matter and nutrients (Salt Flats and Grand Bayou), to the mud and peat soils which are high in organic matter and have correspondingly high concentrations of nutrients (Weeks Bayou and Belle Fontaine). The wide distribution of / roemerianus in the tidal marshes of Mississippi and throughout the distribu- tional range of the species is apparently related in part to the ability of the species to occupy a variety of soil types and nutrient regimes. ACKNOWLEDGMENTS We thank other members of the Botany Section of the Gulf Coast Research Laboratory for assistance with various aspects of this study. Special thanks are due to Helen Gill and Cindy Dickens for typing the manuscript, and to Linda Laird who inked the illustration. REFERENCES CITED Black, C. A. (ed.). 1965a. Methods of Soil Analysis. Part 1. Amer. Soc. of Agron., Inc. Madison, Wisconsin, 770 pp. 1965b. Methods of Soil Analysis. Pari II. Amer. Soc. of Agron., Inc. Madison, Wisconsin. 802 pp. Brupbacher, R. H., J. E. Sedberry. Jr. & W. H. Willis. 1973. The coastal marshlands of Louisiana. Chemical properties of the soil materials. La. Agrk. Exp. Stn. Bull. No. 672. 34 pp. Boyd, C. E- 1970. Influence of organic matter on some character- istics of aquatic soils. Hydrobiologia 36(1): 17 -21. Chabreck, R. H. 1972. Vegetation, water, and soil characteristics of the Louisiana coastal region. La. Agric, Exp. Stn. Bull, No. 664. 72 pp. Coulias, C. L. 1978a. Soils of the inter-trdal marshes of Dixie County, norida. Fh. Sci. 4l(2):8J -90. 1978b. The soils of the intertidal zone of Rookery Bay, Florida. SSSA {Soil Sci, Soc. Am.) Spec. Publ, Set. 42(1): in-iis. & E, R. Gross. 1975, Distribution and properties of some tidal marsh soils of Appalachce Bay, Rorida. SSSA (Soil Sci. Soc. Am.) Spec. Pubi Ser. 39(S);914-919. , 1977. Tidal rnaish soils of Florida’s middle Gulf coast. Soil Crop Sci. Soc. Fla. Proc. 37:121 ^125. DeLaune, R, D., C. N. Reddy, &.W. H. Patrick, Jr. 1981. Accumu- lation of plant nutrients and heavy metah through sedimentation processes and accretion in a Louisiana salt mAish. Estuaries A'. 328-334. R J. Buresh & W. H. Patrick, Jr. 1979. Relationship of soil properties to standing crop biomass of Spartina alterniflora in a Louisiana marsh. Estuarine Coastal Mar. Sci. 8:477-487. Dunstan, W'. M. & H. L. Windom. 1975. The influence of environ- mental changes in heavy metal concentrations on Spartina alterni- flora. Pages 393-405 in: L. E. Cronin (ed.). Estuarine Res. Vol. II. Academic Press, Inc., New York, N.Y. Soils ofJuncus Populations 13 Eleutcrius, L. N, 1972. Marshes of Mississippi. Car/flMtfa 37 :153-168. 1974. An autccological study of Juncus roemerianus. Ph.D, Dis.scrtatioii, Mississippi State University, Staikville. 221 pp. & S, McDaniel. 1978. The salt marsh flora of Mississippi. Castanea 43:86-95. & J, D, Caldwell. 1981. Effect of mineral deficiency on the growth of salt marsh rush, Juncus roemerianus. Gulf B.es, Rept. 7(l):3S-39. Farwell, S. 0., A. E. Sherwood, M. R. Pack & D. F, Adams. 1979. Sulfur compounds volatilized from soils at different moisture contents. Soil Biol. Blochem. 1 1 :41 1 -41 5. George, U. S, & A. D. Antoine. 1982. Denitrification potential of a salt marsh soil: Effect of temperature, pH and substrate concern tration. Soil Biol. Biochem. 14:117-125. Mendelssohn, 1. A. & M. T. Postek. 1982. Elemental analysis of deposits on the roots of Spartina altemiflora Loisel. Am. J. Bot. 69(6):904-912. Palmisano, A. W. 1970. Plant community-soil relationships in Loui- siana coastal maishe.s. Ph.D. Dissertation, Louisiana State Uni- versity, Baton Rouge. 98 pp. &. R. H. Chabreck. 1972. The relationship of plant com- munities and soils of the Louisiana coastal marshes. Presented at 13th annual meeting Louisiana Assn, of Agronomists, Lake Charles. La. March, 1972. Patrick, W. H., Jr. & R. D. DeLaune. 1976. Nitrogen and phosphorus utilization by Spartina altemiflora in a salt marsh in Baiataria Bay, Louisiana. Estuarine Coastal Mar. Sci 4 :59 -64. . 1977. Chemical and biological redox systems affecting nutrient availability in the coastal wetlands, Geosci. Man. 18:131-137. Smith, C. J. & R. D. DeLaune. 1983, Gaseous nitrogen losses from Gulf Coast Northeast Gulf Sci. 6(1): 1-8. 1984. Influence of the rhizo.sphere of Spartina alterni- flora Loisel. on the nitrogen loss from a Louisiana Gulf Coast salt marsh, ifnviron. Exp. Bot. 24(l):91-93. Valiela, I, & J. M, Teal 1974. Nutrienr limitation in salt marsh vege- tation. Pages 547-563 in: R. J. Wcimold and W. H. Quccen (eds.), Ecology of Halophytes. Academic Press, New York, N.Y. Waisel, Y. 1972. Biology of Halophytes. Academic Press, New York, N.Y. 395 pp. Gulf Research Reports Volume 8 | Issue 1 January 1985 The Effects ofWeathered Crude Oil from the M/T Alvenus Spill on Eggs and Yolk-Sac Larvae of Red Drum (Sciaenops ocellatus) George J. Guillen Texas Parks and Wildlife Department Dennis Palafox Texas Parks and Wildlife Department DOI: 10.18785/grr.0801.03 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Guillen, G. J. and D. Palafox. 1985. The Effects ofWeathered Crude Oil from the M/T Alvenus Spill on Eggs and Yolk-Sac Larvae of Red Drum (Sciaenops ocellatus). Gulf Research Reports 8 (l): 15-20. Retrieved from http:// aquila.usm.edu/gcr/vol8/iss 1/3 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research Reports, Vol. 8, No. 1, 15-20, 19S5 THE EFFECTS OF WEATHERED CRUDE OIL FROM THE M/T ALVENUS SPILL ON EGGS AND YOLK-SAC LARVAE OF RED DRUM {SCIAENOPS OCELLATUS) GEORGE J. GUILLEN AND DENNIS PALAFOX Texas Parks and Wildlife Deparnnent, Resource Protection Branch, Seabrook, Texas 77586 ABSTRjlCT The British tanker M/T ALVENUS ran aground 16,1 km south of Cameron, Louisiana, on 30 July 1984. An estimated 10,157 MT of Venezuelan crude oil were spilled into the Gulf of Mexico. Approximately 2,700 MT of the heavy viscous oil impacted beaches and an additional L360 MT remained in the suhtidal areas of wc.st Galveston Island, about 160 km southwest of the accident site. Red drum, which spawn In the Gulf of Mexico in the fall, could have been seriously impacted by oil concentrations potentially lethal lo eggs or larvae. The impact of weathered crude oil on the survival, growth, and morphological development of red drum eggs and larvae was assessed in the laboratory. Equal num- bers of eggs were randomly assigned to one of six treatments of weathered crude oil (control, 50, 100, 500, 1,000 and 2,000 mg/1) and observed through the yolk-sac stage. Theie were no differences in mean survival, length of surviving larvae, and frequency of morphological abnormalities among treatments (Ot < 0*05). In addition, the frequency of spinal deform- ity and abnormal mouth development was low in all treatments. The initial chemical composition of the fresh crude oil and the seasonally warm weather contributed to the natural degradation of the soluble toxic components. INTRODUCTION The British oil tanker M/T ALVENUS ran aground 16,1 km south of Cameron, Louisiana, on 30 July 1984, An estimated 10,157 MT of Venezuelan crude oil were spilled into the Gulf of Mexico. The resulting surface slick drifted in a southwestern direction for 3 days before making land- fall, The path of the slick passed the mouths of three coastal passes, Sabine Pass, Rollover Pass, and the Galveston Bay entrance. Approximately 2,700 MT of oil impacted beaches and an additional J ,360 MT remained in the subtidal areas of Galveston Island, about 160 km southwest of the acci- dent site. In the heavily impacted areas of the west end of the island, submerged oil extended 6.0 to 15.3 m offshore and coated the bottom with a layer 15.2 to 20.3 cm deep. The occunence of the oil spill coincided with the spawn- ing season of red drum (Sciaenops oceilatus). Red drum is a lecreationally and commercially important species distrib- uted along the Atlantic and Gulf of Mexico coasts of the U.S., ranging from New York to Texas. Red drum spawn along the Texas coast beginning in mid- August, peaking in late August and early September, and extending to Novem- ber (Ferret et al. 1980). Spawning usually occurs in or around mouths of passes and adjacent offshore waters (Ferret et al. 1980). During the spawning season large adult red drum are sometimes numerous along the beachfronts (McEachron 1980). Larval and postlarval redfish occupying these habitats range in size from 4.0 to 12.0 mm SL (Pearson 1929, Sabins 1973, and Guillen 1983). Based on the path of the surface slick, known spawning season, and the distribution of eggs and larvae, red drum could have been detrimentally impacted by the oil spill through various mechanisms. These mechanisms include physical coating, lethal toxicity, sublethal toxicity, and physiological incorporation (Moore and Dwyer 1974). Manuscript received June 24, 1 985; accepted September 10, 1985. Laboratory loxicity tests have demonstrated that the embiyonic and larval periods arc the most sensitive stages in the life history of fishes (McKim 1977), Water soluble components of crude oil have been shown to be toxic to adult and juvenile estuarine organisms (Anderson et al. 1974). Results of experiments conducted on eggs and larvae of Pacific herring (Clupea harengus) have demonstrated that water soluble fractions of crude oil increase the occur- rence of gross abnormalities and decrease the growth rate of newly hatched larvae (Smith and Cameron 1979), In addition, less obvious deleterious effects have been observed at the cellular level in Pacific herring larvae (Cameron and Smith 1980). Rabalais et aJ. (1981) reported higher mean mortality and gross abnormalities in red drum eggs and yolk-sac larvae exposed to concentrations of crude oil observed during the Ixtoc I oil spill. The objective of this study was to evaluate the possible effects of weathered M/T ALVENUS crude oil on the early development of red drum. We define weathered crude oil as oil which remained on the bottom in subtidal and intertidal zones after initial landfall on 4 August 1985. The majority of exposed immature red drum would contact this form of oil during the peak spawning period in September. The acute toxicity and sublethal effects of the weathered crude oil were evaluated using a static bioassay on the eggs and resulting yolk-sac larvae of red drum. METHODS Information on the chemical composition of the fresh and weathered crude oil was considered essential for under- standing the possible mechanisms of induced mortality and sublethal effects. The cargo holds of the M/T ALVENUS contained two types of crude oil, Merey and Pilon. Crude oil samples were collected from the cargo holds of the M/T ALVENUS and from Jamaica Beach by Conoco Oil Company personnel (Figure 1). Chemical analyses were 15 16 Guillen and Palafox Figure 1. Area affected by the M/T ALVENUS oil spill. (A = Jamaica Beach, B = Galveston seawall, C = Galveston Bay entrance, D = Roll- over Pass, E = Sabine Pass). performed by the Conoco Refining Technical Services Lab- oratory of Ponca City, Oklahoma (Leeman 1984). The specific gravity at 15,5®C, total sulfur content, heavy metal content, and distillation fractions were determined for both types of fresh crude (ASTM 1984). Except for distillation fractions, the same parameters were measured on weathered oil obtained from Jamaica Beach. Texas Parks and Wildlife Department (TPWD) personnel collected one surface water sample in the surf zone at Jamaica Beach on 7 August and 8 September 1984. The oil content of these samples was determined by the partition gravimetric technique (Rand et al. 1976). Samples of weathered crude oil were collected along Galveston seawall by University of Texas Marine Science Institute and TPWD personnel on 7 August and 28 August 1984, respectively (Figure 1). The oil was analyzed using silica gel column chromatography for percent saturated hydrocarbons, aromatic hydrocarbons, nitrogen, sulfur and oxygen compounds, and asphaltenes (Parker 1984). Quali- tative observations were made on the composition and quantity of individual compounds within the aromatic frac- tion using a Perkin Elmer model 910 gas chromatograph equipped with a flame ionization detector (Parker 1984). A portion of the crude oil obtained on 28 August 1984 was used for the static bioassay (Peltier 1978). Exposure concentrations of 0, 50, 100, 500, 1,000 and 2,000 mg/1 crude oil were selected. Three replicate 5-liter McDonald jars containing synthetic seawater prepared from Instant Ocean^ were used for each treatment concentration. These clear fiberglass cylindrical jars measured approximately 38.1 cm tall with a diameter of 14.3 cm. The oil was added to the water at 2000 hours on 17 September 1984. The salinity, temperature, and dissolved oxygen in all containers were 35 ppt, 26®C, and 6.8 mg/l, respectively. Air stones were used to gently aerate and circulate the water and oil. Recently fertilized 1-hour-old eggs were obtained from spawning red drum maintained in captivity at the TPWD John Wilson Fish Flatchery at Flour Bluff, Texas. The salin- ity, temperature, and dissolved oxygen in spawning tanks were 36 ppt, 26®C, and 6.9 mg/1, respectively. Twenty-five eggs were randomly selected and placed into each container on 17 September 1984 between 2130 and 2230 hours. Constant overhead fluorescent illumination was provided and the room temperature was thermostatically maintained al 25‘*C. Salinity, water temperature, and dissolved oxygen were monitored in each container at 24, 48, and approxi- mately 64 hours after introduction of the eggs. Qualitative observations of the amount of visible floating oil, number of unhaiched eggs, and dead and deformed larvae were made. The bioassay was terminated and the yolk-sac larvae ^Reference to trade names does not imply endorsement. Effects of Crude Oil on red Drum Eggs and Larvae 17 were randomly removed between 0950 and 1315 hours on 20 September 1984, approximately 60 to 67 hours postfer- tilization and 36 to 43 hours posthalching. The number of live and abnormal live larvae were counted, larvae were considered dead if the body was opaque and if no opercular and/or body movement was o'bserv'ed after tactile stimula- tion by a small needle. Larvae were considered abnormal if spinal curvature, incomplete mouth and gut development, or other gross deformities were observed. Notochord length (NL) of three randomly selected larvae from each container was measured with an ocular micrometer. A Kruskal-Wallis one-way analysis of variance was used to test the null hypotheses that percent mortality, percent abnormality of surviving larvae, and mean lengths were equal for all treatments (Daniels 1978), A significance level of a = 0.05 was preselected before the analyses. RESULTS The oil spilled from the M/T ALVENUS was a heavy viscous crude (Tables 1 and 2). For comparison, an outline of the typical constituents of crude oil, based on distillation fractions, is provided (Table 3) (Morrison and Boyd 1973). The two types of crude oil spilled, Merey and Pilon, exhib- ited relatively higli specific gravities. Lighter alkanes and cycloalkanes were absent. Approximately 70% of the fresh crude oil was composed of insoluble high molecular weight asphaltenes (Tables 1 and 3). In addition, these crude oils contained a large fraction of aromatic hydrocarbons. The weathered crude oil contained high concentrations of water and sand (Tables 2 and 4). The percentage of high molecular weight asphaltenes per unit of oil was slightly TABLE I Physcal and chemical properties of Merey and Pilon crude oil spilled from the M/T ALVENUS on 30 July 1984. Summary of analyses pCTfonned by Conoco laboratories. Attiibute/Chemical Merey Pilon Specific gravity at 15.5°C 0.958 0.978 3 otal sulfur, wt % 2.5 2.7 Heavy metals, ppm Vanadium 265.0 265.0 Nickel 60.0 70.0 Copper <0.5 <0.5 Fractional distillation, temperature cut range (°C) % yield by weight Ci-Cs gases 0.10 - 37.8 - 85.0 1.49 - 85.0 - 193.3 3.96 - 193.3 - 232.2 3.12 3.84 232.2 - 265.5 3.92 3.26 265.5 - 335.0 10.88 10,72 335.0 - 385.0 8.91 9.37 385.0 - 418.3 6.20 6.46 418.3-515.5 14.09 15.60 515.5 + 47.35 50.80 liigher in the late August beach sample, relative to the earlier beach sample. In addition, the percentage of total aromatic hydrocarbons per unit of oil had decreased TABLE 2 physical and chemical properties of weathered crude oil spilled from the M/T ALVENUS and collected from Jamaica Beach on 9 August 1984, Summary of analyses performed by Conoco laboratories. Attiibute/Chemical Level % wt Water 15.0 Solids 65.0 Oil Analysis of oil component 20.0 Spedfic gravity at 15.5°C 0.9745 % wt sulfur Heavy metals, ppm 2.6 Vanadium 280.0 Nickel 77.0 Copper 1.0 TABLE 3 Typical hydrocarbon constituents of aude oil. Fraction 1 Distillation Carbon number temperature (®C) Gas below 20 C 1 -C 4 Petroleum ether 20-60 C 5 — Cfi Ligroin (light naphtha) 60-100 Cfi-C? Natural gasoline 40-205 C 5 — Cio and cycloalkanes. Kerosene 175-325 Uid -C 18 and aromatics. Gas oils Residual oils - 300-400 Cl 6 -C 2 S asphaltenes above 400 Above Cj s , long chains attached to cyclic hydrocarbons. Molecular weight = > 20 . 000 . TABLE 4 Results of silica gel column chromatography conducted by University of Texas laboratories on the petroleum fraction of oil spilled from the M/T ALVENUS, and collected from Galveston Island seawall on 7 and 28 August 1984. Percent Composition Component 8-7-84 8-28-84 Sand and insolubles Petroleum fractions 40.70 52.00 Saturated hydrocarbons 14,83 12.84 Aromatic hydrocarbons 21.34 15.58 N,S,0 compounds 6.50 4.86 Asphaltenes 16.60 15.17 18 Guillen and Palafox slightly (Table 4). Based on qualitative observations of the gas-liquid chrornaiogram, low molecular weight aromatics such as benzene through phenanthrene were largely absent in the weathered crude oil. These observations and the in- creased level of sand and insolubles at progressively later dates indicated natural weathering processes were active during the spill. Analyses of the fresh and weathered crude oils revealed higli levels of vanadium (Tables 1 and 2). Vanadium con- tent did not appear to decrease with weathering. This strongly indicated that vanadium compounds present in the weathered oil were fairly stable. Surface water samples collected at the beach on 7 August and 8 September 1984 yielded oil levels of 1,190 mg/1 and 43 mg/h respectively. Water quality parameters measured varied little through- out the experiment. Dissolved oxygen never fell below 6.2 ing/1 in any container. Water temperature varied between 25 and 26T. Salinity fluctuated between 34 and 37 ppt. Live larvae and eggs were observed in all containers on 8 September 1984 at 1900 hours. Appreciable amounts of sur- face oH had accumulated in various containers of the 50, 100, 500, and 2,000 mg/1 treatments (Table 5). On 9 September 1984 at 0735 hours, one to three dead larvae exliibiting spinal curvature were obser\'cd in replicates one and two of the l.ODO-mg/l treatment. Dead and deformed larvae were also observed in replicate two of the 2,000-mg/l treatment and replicates (wo and three of the 1,000-mg/l treatment. Mortality of red drum eggs and yolk-sac larvae varied erratically between treatments (Table 5). In addition, high mortality was observed in replicate one of the control ex- posure. No statistically significant differences in mortality occurred in any of the treatments. Visible sublethal effects were limited to abnormal spinal curvature and were infre- quent and statistically insignificant across all concentrations (Table 6). The size of the yolk-sac larvae ranged between 1.7 and 2.8 mm NL and averaged 2.3 mm NL. There were no significant differences in size of larvae among treatments (Table 7). TABLE 5 Percent mortality of red drum eggs and larvae after a 64-h exposure to six concentrations of weathered crude oil spilled from the M/T ALVENUS. S denotes visible surface oil observed. Concentration mg/l Replicate 1 2 3 mean 0 60 4 0 21 50 16^ 20 32 23 100 24 0* 32 19 500 0 24® 24 16 1,000 68 24 32 41 2,000 40® 40® 16® 32 TABLE 6 Percent incidence of spinal curvature in surviving red drum yolk-sac larvae after a 64^h exposure to six concentrations of weathered crude oil spilled from the M/T ALVENUS. S denotes visible surface oil observed. Concentration mg/l Replicate 1 2 3 mean 0 0 0 0 0 50 0® 0 6 2 100 0 0® 0 0 500 4 5® 0 3 1,000 0 0 0 0 2,000 0® 0® 0* 0 TABLE 7 Notochord length range (RG, mm) and mean notochord length (NL, mm) of surviving yolk-sac larvae after a 64 -h exposure to six concentrations of weathered crude oil spilled from (he M/T ALVENUS. Grand mean is denoted hy NL. S denotes surface oil observed. Concentration mg/1 Replicate 0 50 100 500 1000 2000 1 RG 2.0-2.3 1,7-1.9 2.4-2.6 2.5-2.8 2.2-2.6 2.3-2,5 NL 2.1 1.8® 2.5 2.7 2.4 2.4® 2 RG 2.3-2.5 2. 2- 2.4 2.1 -2.3 2.3-2.5 2.2-2.3 2.3-2.4 NL 2.4 2.3 2.2® 2.4® 2.2 2.4® 3 RG 2.3-2.4 2.1 -2.4 2.2-2.5 2. 4 -2.5 2.2-2.3 2.3-2.4 NL 2.3 2.3 2.4 2.5 2.2 2.4® Total NL 2.3 2.1 2.4 2.5 2.3 2.4 Effects of Crude Oil on Red Drum Eggs and Larvae 19 DISCUSSION The high mortahty observed in one of the control repli- cates suggests that other factors, besides oil, may be affect- ing the survival of red drum eggs and larvae in these experi- ments. Hydrological variables monitored were well within the range necessary for optimum survrval (Holt et al. 1981). Ammonia may have been a problem to larvae in oil-treated containers. Degradation of the oil by bacteria may have generated liigh concentrations of un-ionized ammonia. Con- centrations as low as 0.55 mg/1 of un ionized ammonia have been shown to signilicantly increase mortality in larval red drum (Holt and Arnold 1983). However, low stocking densities and the use of eggs and yolk-sac larvae virtually eliminated the introduction of ammonia by metabolic end products and/or external food sources. Based on previous experience with the culture of red drum, the high mortality observed in the control replicates may have been caused by bacterial containirration (Holt and McCarty 1984). The higlier mean mortalities observed in the 1 ,000- and 2,000-mgA treatments suggests that the oil may increase larval mortality at and exceeding these levels. However, the incidence of gross abnormalities was low in these containers. Based on our observations, the weathered crude oil exhib- ited low toxicity to red drum eggs and larvae. A static bio- assay conducted with adult pin fish {Lagodon rhomboides) substantiates the relatively low toxicity of this weathered crude oil to estuarine fish (Spears 1984). The reported 48 hour LCso was 19,500 mg/1 of weathered crude oil. How- ever, adult fish are generally more tolerant to pollutants than egg and larval stages (McKim 1977). The reduced toxicity observed at low treatment levels is related to the chemical composition of the weathered oil and the metabolism of aromatic hydrocarbons by the egg and larval stages of fish. Petroleum crude oil is a complex mixture of hydrocarbons and associated inorganic com- pounds. Each of these chemicals exhibits its own associated toxicity to aquatic organisms. The acute toxicities of many of these compounds have been determined for various species, but little information exists on their synergistic effects. There is general agreement that the acute toxicity of crude uii is positively correlated with the aromatic hydro- carbon content. Aromatics are generally more toxic tharv cycloalkanes which are in turn more toxic than paraffins. Within each of these hydrocarbon groups the smaller molecules are generally more acutely toxic. The toxicity of aromatic hydrocarbons increases with increasing molecular size from benezene to phenanthrene, although the 4- and 5 -ring aromatics are not acutely toxic (Davis et al. 1984). However, these 4- and S-ring polynuclear aromatic hydro- carbons, such as ben7.o(a:)pyrene, are known carcinogens (Malins and Hodgins 1981). The crude oil spiUed from the M/T ALVENUS was a heavy viscous type. The majority of lighter, toxic alkanes and cycloalkanes were absent from the oils. However, at least 2\% of the crude oil was composed of aromatic hydro- carbons (Table 4), Based on qualitative observations of the gas-Uquid chromatogram, the majority of these compounds were high molecular weiglii, water insoluble, polycyclic aromatic hydrocarbons (PAH). The majority of the water soluble and light hydrocarbons were probably lost during the initial 3 days of weathering at sea. These soluble phases usually include benzene and alkylbenzenes. However, the less soluble 2- and 3-ring aromatic compounds that remain are generally more acutely toxic (Anderson et al. 1974). As indicated by the gas-liquid chromatogram, the weathered crude oil did not contain a high percentage of these low molecular weight polycyclic aromatic hydrocarbons. Micro- bial and photochemical degradation at sea may partly ac- count for this observation. Lee and Ryan (1983) reported that the lialf-Iives of various PAHs were reduced to approxi- mately 3 days during September (28®C) in a controlled microcosm experiment . The stnicture of the red drum eggs and yolk-sac larvae may have also provided some protection against the adverse effects of petroleum hydrocarbons. Korn and Rice (1981) found that eggs of coho salmon (Oncorhynchus kttsuich) were more tolerant of aromatic hydrocarbons than alevins or fry. They suggested that the choroin, the protective membrane of the egg, prevented the rapid uptake of aromatic hydrocarbons present in the water. The amount of yolk also influenced sensitivity because aromatic hydrocarbons were selectively partitioned into the yolk, thus reducing their availability to the embryo until yolk absorption. The elevated level of vanadium observed in the fresh and weathered crude oil was evidently nontoxic. The elemental form of vanadium is insoluble in water. However, some compounds such as vanadium pentoxide are soluble and have induced chronic toxicity at levels above 0.08 mg/1 in larval freshwater flagfish (Jordanella floridae) (Holdway and Sprague 1979), Analyses of the weathered crude oil suggests that vanadium compounds were relatively stable and resistant to chemical and/or biological degradation. Long-term secondary effects to planktonic food items of larval red drum may have occurred but would be difficult to quantify, Dahl el aJ. (1983) reported that growth rates of copepod populations declined in controlled medium- scaled ecosystems when exposed to a 5 mm layer of surface crude oil. The short-term effects of the M/T ALVENUS oil spill on red drum eggs and larvae were difficult to determine, but were probably limited to increased mortality caused by the physical coating of eggs and larvae in the field by floating heavy crude oil. The initial chemical composition of the fresh crude oil and the seasonaEy warm weather contrib- uted to the natural degradation of the more soluble toxic components. Based on the low mortality, infrequency of gross deformities, and the similar sizes and developmental stages of all surviving larvae observed in the bioassay, the weathered oil could be classified as relatively nontoxic. 20 GUILLEN AND PaLAFOX ACKN OWLEDGMENTS We thank Mr. A. W. Moffett and Drs. P. L. Parker and Brian Cain for critically reading the manuscript, The infor- mation provided by Dr. P. L. Parker and Mr, J. C. Leeman on the chemical composition of the oil is greatly appre- ciated. We thank Mr. Gene McCarthy and the entire staff of the John Wilson State Fish Hatchery for their assistance in setting up the experiment. REFERENCES CITED American Society for Testing and Matenal.s. 1984. Annual Book of ASTM Standards. ASTM, Philadelphia, Pennsylvania. Anderson. J. W.. J. M. Neff, B. A. Cox, H. E, Tatum, & G. M. Hightower. 1974. Characteristics of dispersions and water- soluble extracts of crude and refined oils and Ihcir toxidty to estuarine crustaceans and f\sh.Mar. Biol. 27:75-88. Cameron, J. A. & R. L, Smith. 1980. UUrastructuial effects of crude oil on early life stages of Pacific herring. 7>a«y. Am. Fisli. Soc. 109-224-228. Dahl, E., M. Laakc, K. Tjessem, K, Eberlcin & B. Bohle. 1983. Effects of Ekofisk crude oil on an enclosed planktonic ecosys- tem. Mar. Ecol Prog. Set. 14:81-91, Daniels, W. W. 1978. Applied Nonparametric Statistics. Houghton Mifflin Company, Dallas, Texas. Davis, W. P., D. E. Horr, G. 1. Scott & P. F. Sheridan. 1984. Fisher- ies resource impacts from spills of oil or hazardous substances. Pages 157-172 in: J. P, Cairns, Jr. and A. L. Buikema, Jr. (eds.). Restoration of habitats Impacted by oil spills. Butter- worth Publishers, Boston, Massachusetts. Guillen, G. J. 1983. Comparative utilization of shallow water habits at Galveston, Texas by ijnmatutc marine fish. M.S. thesis, Texas A&M University. College Station, Texas. Holdway, D. A. & J. B. Sprague, 1979. Chronic toxidty of vana- dium Jo flagfish. Water Res. 13:905-910. Holt, G. & G. McCarthy. 1984. Personal communications. Univer- sity of Texas Marine Science Institute of Port Aransas and John Wilson Hatchery, Texas Parks and Wildlife Dept., Flour Bluff, Texas Holt, G. J. 8l C. R, Arnold. 1983. Effects of ammonia and nitrite on growth and survival of red drum eggs and larvae. Trans. Am. Fish. Soc. 112:314-318. Holt, J., R, Godbout & C. R. Arnold. 1981. Effects of temperature and salinity on egg hatching and larval survival of red drum, Sciacnops ocelkta. U.S. Nat. Mar. Fish. Serv. Fish. Bull. 79: 569-573: Korn, S. & S. Rice. 1981. Sensitivity to and accumulation and depuration of aromatic petroleum components by early life stages of coho salmon iOncorhynchus kisutch). Rapp. P. V. Reun, Cons. Inf. Explor. Sier 178:87-94. Lee, R, F. & C. Ryan. 1983. Microbial and photochemical degrada- tion of polycyclic aromatic hydrocarbons in estuarine waters and sediments. Can, J. Fish. AtjUat. Sci. 40:86-94, Leeman, J, E. 1984. Alvenus crude oil analyses reports. Unpublished report. Conoco Inc., Houston, Texas. Malms, D. C. & H. 0. Hodgins. 1981. Petroleum and marine fishes: a review of uptake, disposition, and effects. Environ. Sci. & Technol. 15:1272-1280. McEachron, L. W. 1980. Gulf pier and jetty finfish catch statistics for the Gulf waters of Texas, September 1978-August 1979. Texas Parks and Wildlife Coastal Fisheries Branch Management Data Series No. 1 1 . McKim, J. M. 1977. Evaluation of tests with early life history stages of fish for predicting long-term toxicity. J. Fish. Res. Board Can. 77:1148-1154. Moore, S, F. &. R. L. Dwyer. 1974. Effects of oil on marine organ- isms: a critical assessment of published data. Water Res. 8:819- 827. Morrison, R. T. & R. N. Boyd. 1973. Organic Chemistry, 3rd edi- tion. Allyn and Bacon, Boston, Massachusetts. Parker, P. L. 1984. Chemical composition of Alvenus oil. Unpub- lished report. University of Texas Marine Science Institute, Port Aransas, Texas. Pearson, J. C. 1929. Natural history and conservation of redfish and other commercial sciaenids of the Texas coast. Bull U.S. Bur. Fish. 44:129-214. Peltier, W. 1978. Methods for measuring {he acute toxicity of effluents to aquatic organisms. Environmental Protection Agency. EPA-600/4-76-012, Oncinnati, Ohio. Ferret, W. S., J. E. Weaver, R. O. Williams, P. L. Johansen, T. D. McllWain, R. C. Raulerson & W. M. Tatum. 1980. Fislwry pro- files of red drum and spotted seairout. Gulf Slates Marine Fish- eries Commission, Ocean Springs, Mississippi. Rabalais, S. C., C. R. Arnold & N. S. Wohlschlag. 1981. The effects of Ixtoc 1 oil on the eggs and larvae of red drum {Sciaenops ocellata). Tex. J, Sci. 33 33-38. Rand, M. C., A, E. Greenberg, M. J, Taras & M. A. Franson (eds.). 1976, Standard methods for the examination of water and waste- water. American PubBc Health Association, Washington, D.C. Sabins, D. S. 1973. Diel studies of larval and juvenile fishes of the Caminada Pass area. Louisiana. M.S. thesis, Louisiana State University, Baton Rouge. Smith, R. L. & J. A. Cameron. 1979. Effect of water soluble frac- tion of Prudhoe Bay crude oil on embryonic development of Pacific herring. Trans. Am. Fish. Soc. 108:70-75, Spears, R. 1984. Forty-eight hour static bioassay of Venezuelan crude oil. Resource Protection Report. Texas Parks and Wildlife Dept., Rockport, Texas. Gulf Research Reports Volume 8 | Issue 1 January 1985 Metabolic Activity of the Epiphytic Community Associated with Spartina alterniflora Wilmer C. Stowe Lake Erie College James G. Gosselink Louisiana State University DOI: 10.18785/grr.0801.04 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Stowe; W. C. andj. G. Gosselink. 1985. Metabolic Activity of the Epiphytic Community Associated with Spartina alterniflora. Gulf Research Reports 8 (l): 21-25. Retrieved from http://aquila.usm.edu/gcr/vol8 /issl/4 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research Reports, Vol. 8, No, 1, 21-25, 1985 METABOLIC ACTIVITY OF THE EPIPHYTIC COMMUNITY ASSOCIATED WITH SPARTINA ALTERNIFLORA WILMER C. STOWE’ AND JAMES G. GOSSELINK^ ’ Lake Erie College, Painesville, Ohio 44060 ^Department of Marine Science, Louimna State University, Baton Rouge, Louisiana 70803 ABSTRACT Priniaiy production and respiration rates were determined for two epiphytic communities associated with Spardm aticrniflora Loiscl., in the southwestern Barataria Bay area of Louisiana. The communities studied were: (1) a shoreline community and (2) a community 1,5 meters inland from the shoreline site. Annual mean net production and respiration rates for the shoreline community were 25.8 and —19.6 mgC * (m^ substrate area)'’ ■ h"’ respectively; whereas the inland community showed corresponding rates of -3.3 and -12.5 mg C • substrate areaT’ • h"’, respectively. Thus, the shoreline community was a net contributor to system production; the inland community was an energy sink. The inland community was elevated 15 to 20 cm above the shoreline community, lacked the conspicuous filamentous algal growth common at the shoreline location, and had a significantly smaller diatom population. The role of epiphytes is speculated to be one of quality rather than quantity production. INTRODUCTION Production by epiphytic algae has been found to vary in different environments. Using the method, Allen (1971) found epiphytic production on submerged sub- strates to be 600 g C * m~^ ♦ y'’ and 71 gC • m"^ * y"’ on emergent substrates. In the spring of the year, Jones (1980) using radioisotope technique observed a rate of 24.8 mg C • (m^ substrate area)"’ • h"’ for epiphytes associated with Spanina altemiflora in a Georgia salt marsh. Jones (1968) found the epiphytes on Thalassia testudinum Konig. produced 315 g C • * y’ , or about 35% of the host- epiphyte complex production. Studies by Sand-Jensen (1977) showed a significant reduction of host productivity as a result of epiphytosis. Penhale (1977) suggested that epiphyte shading could reduce host photosynthesis. While the community structure of the microalgal popu- lation attached to (Stowe 1980, 1982) and beneath (Blum 1968, Sullivan 1978) the S. altermflora canopy have been studied, only the report of Jones (1980) has investigated the productivity of the S, altemiflora epiphytic community. Others (Pomeroy 1959, Gallagher and Daiber 1973) have investigated sediment production beneath the grass canopy. This report describes the productivity and respiration of the epiphytic community associated with S, altemiflora in a salt marsh of the Barataria estuary, Louisiana. description of the study area The Barataria estuary is an inteidistributary, deltaic basin of the Mississippi River system (Russell 1936, Gaghano and van Beek 1970). It is a large (6,300 km^), shallow series of bays and lakes flanked by marshes. The water is saline at tlie coast, grading through brackish to fresh at the upper reaches of the estuary (Day et al. 1973). Tidal cycles are diurnal rather than semidiurnal with a Manuscript received March 25, 1985; accepted August 20, 1985. 0.3 m average amplitude (Baumann 1980). Airplane Uke (N 29'’13.25', W 90'’06.18') was selected because a number of other ecological parameters were being studied at lliis site (Day et al. 1973). This marsh lies at a +5 cm relative to local mean water level. A natural levee rises from the shoreline, cresting about 1.5 to 3 m inland with an elevation of 15-20 cm. Maximum average water level of +20 cm occurs in September and a minimum level of —12 cm occurs in January. Baumann’s inundation studies (1980) reported 260 marsh floodings per year with a mean duration of 17 hours per flood. The physical environment of the sampling area has been described further by Day et al. (1973) and Stowe (1980, 1982). MATERIALS AND METHODS Twelve times between June 1970 and May 1971, S. altemiflora culms were collected from the Airplane Lake site. Twenty -four culms were collected immediately along the exposed edge of the marsh and an equal number from the crest of the natural levee 1.5 rn inland from the shore- line site. The inland site was elevated about 15 cm above the shoreline site. The culms were severed at the sediment surface, placed in individual plastic bags and returned to the field laboratory under refrigeration. Macroscopic algal biomass was determined from culm scraping, dried at SO^C for 24 hours, and weighed on an analytical balance. Microscopic algal density (almost all dia- toms) was determined by the methods described by Stowe (1982). Production of the epiphytic community was measured by a modification of tbe UgiU-dark bottle method (Howard and Menzies 1969). Two bottom 10-cm lengths of the collected culms were placed in each of 24 BOD bottles. Water used for incubation was collected from Airplane Lake in a 20-liter carboy and allowed to settle for at least 2 weeks. The BOD bottles were filled by syphoning from 21 22 Stowe and Gosselink the middle of the ca/boy, allowing each bottle to overflow, replacing the volume in the BOD bottles approximately three limes. Two uninoculated control bottles were also filled in the manner previously described. The bottom 10 cm of the culms were used because structural studies indicated that 70% of the diatoms and practically all of the macroscopic algae were confined to this region (Day et al. 1973 and Stowe 1982). Gosselink et al. (1977) observed no net CO 2 uptake by the bases of epiphyte-free, greenhouse -grown S. aUermflora and very low respiration rates. Therefore it was assumed that all O 2 changes were the result of epiphytes. Six shoreline and six inland bottles were incubated in a dark ice chest at ambient temperatures. Six other bottles with shoreline culms were incubated in direct sunlight wliiie submerged in ambient temperature tap water in a large wash tub. Six bottles with inland culms were incubated in the shade of Distichlis spicata. Both light regimes approxi- mated the natural conditions of the field. Incubation of these culms began by mid-morning within 1.5 hours of collection and was carried out for 2 hours. Dissolved oxygen (DO) was determined from control bottles at the beginning of incubation and on the control and test bottles at the end of the 2-hour incubation period. Initially, DO determination was done by a modified Winkler titration method (Strickland and Parsons 1968). Later, DO was determined polarographicalJy with the O 2 sensor mem- brane fitting approximately one-third of the way down into the bottle The water, during 1X3 measurement, was stirred moderately with a magnetic stirrer. After determination of DO, the total water volume was measured to the nearest ml. Net production and respiration were calculated as the difference between initial and final DO in the Ught and dark bottles, respectively, with control correction, Dissolved oxygen concentration was converted to mg carbon fixed or released by a modification of the method described by Strickland and Parsons (1968). The average surface area of the culms was calculated by measuring the diameter of the lower portion of the culm and assuming it to be a cylinder 10 cm long. Fifteen culms collected from each site monthly were used in this deter- mination. RESULTS AND DISCUSSION Four genera of macroscopic aJgae dominated the epi- phytic community at the shoreline site. The macroscopic algae showed distinct seasonal variations in abundance (Figure I) (Day et al. \911). Polysiphonia sp, and Poatrychia sp. dominated from spring to fall, Ectocarpus sp. and Emeromorpha sp. dominated during the winter. These algae rarely occurred more than 50 cm inland. They were usually limited to a horizontal band 10 cm wide parallel to the shoreline. Eciocarpus sp, and Enteromorpha sp. grew on mud flats and other substrates as well as on S', alterniflora. BQitrvctMQ a Polvai ohoDifl Months Figure 1. Seasonal biomass of the four dominant macroscopic algae. The dominant microscopic epiphytes were diatoms. Diatoms occurred at densities of about 1.8 X lO^ per cm*^ of culm surface area and decreased in density with distance from the shoreline and height on the culm (Stowe, 1982). They also varied seasonally with peak density on the bottom 10 cm of the host culm occurring in December- Januaiy (Stowe 1982). Further discussion of the epiphytic diatoms can be found in Stowe (J982). Shoreline community mean metabolic rates were 25.9 (±12,4) and -19,6 (±11.3) mg C • (m^ substrate areaf^ • h“' for net production and respiration, respectively (mean ± standard deviation). Inland communily rates were —3.3 (±9,5) and —12.5 (±8,3) mgC • (in^ substrate areaX* • respectively. Table 1 presents the F values calculated for separate one-way analyses of variance for shoreline and in- land net production and respiration. Highly significant F values indicate that net production was significantly influ- enced by location and time of year. Respiration rate was not influenced by location; however, significant F values indicated that respiration varied seasonally. Culm counts of standing materiaJ indicated a density of 220 and 360 m"^ for the shoreline and inland communities, respec- tively. The average cuhn surface area for a bottom 10-cm section was 27.9 and 27 cm^ , respectively, for the shoreline and inland sites. Culm surface area per square meter of marsh surface was 6124 and 9207 cm^ for the lower 10-cm section of shoreline and inland culms. TABLE 1 F values for separate one-way ANOVA calculations for the following interactions. Nei Production shoreline vs inland 44.72** shoreline vs sampling date 18.33** inland vs sampling date 27.30* + Respiration shoreline vs iniand 2.41 shoreline vs sampling date 32.47** inland vs sampling date 30.44** * *Signiricant at the ,99 probability level. Metabolic activity Associated with Spartina 23 Seasonal trends of net production with standard devia- tions are presented in Figure 2. Shoreline net production Figure 2, Seasonal variation in net production for the shoreline ( — ) and inland ( ) communities. shows a bimodal distribution with midspring and October- November peaks. This bimodality follows closely the sea- sonal biomass distribution of Bostrychia and Poiysiphonia (Figure 1). Following the November decline, the produc- tion rate remains constant during the winter, then begins a spring rise. Bostr}>chia Poiysiphonia were seldom found in the inland community. Inland net production was posi- tive during the late fall and early spring, but was negative the remainder of the year. The two communities had similar production rates during the winter when filamentous epiphytes were scarce.. Even though epiphytic diatoms peak during the winter (Stowe 1982), they do not contribute significantly to net production. This observation is sup- ported by the reports of several other authors (Penhale 1977, Pomeroy 1960, Sand-Jensen 1977, and Gosselink et al. 1977). In contrast, the inland community was dominated by unicellular algae, predominately diatoms. Net production was low and negative in the late summer when S. alterni- flora stands were most dense reducing light penetration to the marsh floor. Conversely, net production became a positive contributor during the winter when the 5. alterni- ftora canopy was more open. Shading and dessication were possible controlling factors of inland productivity. Since light could reach the shoreline community from the water side, low light was not considered to be a limiting factor here. The inland community with its elevation of 15-20 cm above the shoreline community was less frequently flooded, therefore more likely to have dessication stress. The work of Dawes et al. (1978) and unpublished work of one of the present authors (WCS) indicates that macroscopic estuarine algae recover rapidly from dessication; we are not certain that the same can be said for the unicellular forms. Very Irigh seasonal respiratory rates were calculated for the epiphytic community (Figure 3). At limes these lespira- Figuie 3. Seasonal variation in lespiration foi the shoreline ( — and inland < > communities. tion rates equaled or exceeded calculated net production values. Since there was no significant difference between the two communities and because the curves of Figure 3 are very similar, one might assume that the communities are similar. However, this is not the case (see description of the area and Stowe 1980, 1982). The shoreline macroscopic algae were often inhabitated by invertebrates (such as small crustaceans and nematodes) wliich contributed to respira- tion. These herbivores reached maximal levels during peak net production. Contributors to greater respiration rates were the larger bacterial (Hood and Colmer 1971), fungal, 24 Stowe and Gosselink and meiofaunal (Meyers et al, 1970) communities which have been observed inland. These coininunities, although different, are sufficiently dense to i^ve similar rates. The communities had similar respiration rates per substrate area. The rate per marsh surface area was significantly higher inland because of the greater culm density. MetaboDc averages did not present a complete picture of this community. Higli variability was a significant character- istic of these communities (note standard deviations in Fig- ures 2 and 3). Variation in colonization among culms was shown by large standard deviations in the calculated meta- bolic rates. The calculated standard deviations in this study were often greater than half the corresponding mean values. These large deviations should be expected when considering the patchy distribution of macroscopic algae. Grazing impact, while not assessed, could be significant. During the spring and fall, amphipod populations were con- centrated in the epiphytic macroalgal masses (personal observation) and were present in much larger numbers than at any other time. R. E. Condrey (personal communica- tion) had observed several other types of crustaceans graz- ing in the epiphytic algal masses. These herbivore maxima occurred during peak net production. While we are con- vinced that the November production and biomass decline was related to seasonal lowering of the water level (Stowe 1982), the decline of Bostrychia and Polysiphonia in May was not so easily attributed to water level fluctuation. Per- haps the observations of Cattaneo (1983) in Canada are applicable and grazers were responsible for the May decline. Jones (1980), working on Sapelo Island, Georgia, in early April, calculated an epiphytic production of 24.8 mg C • (m^ substrate area)"* • h"^ with a range of 15.3 to 45.5. Since Sapelo Island is a little farther north than Barataria Bay» their early April could be comparable to our late March. Our late March net production average was 25.4 mg C • (m^ substrate area)"^ • h"^ (s = 13). Considering the differences in techniques used and the areas studied, these results are remarkably similar. On this basis, it is tempting to speculate that these results have broader application than just to the Louisiana coast. Initially the authors thought of the salt marsh S. alterni- flora as a massive substratum for production of epiphytes. This was not true in Airplane Lake. In this study, net epiphytic productive contribution was limited to a narrow active band paralleling the shoreline. Inland from this band the epiphytic community was an energy sink. Thus epiphy- tic contribution to total marsh production was low (Day et al. 1973). Mason and Bryant (1975) found a freshwater epiphytic community to be a richer source of total nitrogen and phosphorous than the nearby sediments. Perhaps the role of the epiphytic community is one of quality produc- tion rather than quantity. REFERENCES CITED Allen, H. L. 1971. Primary productivity, chemo-organo trophy, and nutritional interaction of epiphytic algae and bacteria on macrophytes In the littoral of a lake. Ecol, Monogr. 41 ;97-127. Baumann, R. II. 1980. Mechanisrhs of maintaining marsh elevation in a subsiding environment. Unpublished M.S. thesij;, Louisiana State University, Baton Rouge, 91 pp. Blum, J. L. 1968. Salt marsh Spartina and associated algae. £coi. Monogr. 38:199-221. Cattaneo, A. 1983. Grazing on epiphytes. Limnol. Oceanogr. 28: 124-132. Dawes. C. J., R. E, Moon, & M. A. Davis. 1978. The pliotosynthetic and respiratory rates and tolerances of benthic algae from a mangrove and salt marsh estuary; a comparative study. Estuarine Coastal Mar. Sd. 6 ; 1 7 5 - 1 8 5 . Day, J, W., Jr., W. G. Smith, P. R. Wagner, & W. C. Stowe. 1973, Community Structure and Energy Flow in a Salt Marsh and Shal- low Bay Estuarine System in Louisiana. Office of Sea Grant Development, Centex for Wetland Resources, Louisiana State University, Baton Rouge. 79 pp. Gagliano, S. W. & J. L. van Beek. 1970. Geologic and geomorphic aspects of deltaic processes, Mississippi delta system. In: S. W. GagUano, R. Muller. P. Light, and M. Al-Awady (eds.X Hydrologic and Geohgio Studies of Coastal Louisiana. Coastal Studies Insti- tute and Department of Marine Science, Louisiana Slate Univer- sity, Baton Rouge. Voi. 1. 140 pp. Gallagher, J. L. & 1'. C. Diabei. 1973. Did rhythms in edaphic community metabolism in a Delaware salt marsh. Ecology 54: 1160-1163, Gosselink, I. G., C. S. Hopkimon, k R. T. Panondo. 1977. Com- mon marsh plant spedes of the Gulf Coast area. Vol. 1. Produc- tivity, Vol, 11. Growth Dynamics. Tech. Rept. D'7744 Environ- mental Effects Laboratory, U.S- Army Engineer Waterways Experiment Station, Vicksburg, Mississippi. Hood, M. .4. & A. R. Colmei. 1971. Seasonal bacterial studies in Barataria Bay. Coastal Studies Bull. 6;l6-26. Howard, K, L. & R, J. Menzies. 1969. Distribution and production of Sargassum In the waters of the Carolina Coast. Bot. Mar. 7: 244-254. Jones, J. A. 1968. Primary productivity by the tropical marine tur- tle grass, Thalassia testudinum Konig, and its epiphytes. Unpub- lished Ph D. thesis. University of Miami, Miami. Florida. 197 pp, Jones, R, C. 1980. Productivity of algal epiphytes in a Georgia salt marsh: Effects of inundation frequency and implications for total marsh productivity. £sfz/i7riejf 3:315-317, Mason, C. F. & R. J. Bryant. 1975, Periphyton production and graz- ing by chiionomids in Alderfen Broad, Norfolk. Fwhw. Biol. 5: 271-277. Meyers, S. P., M. L. Nicholson, J. Rhee, P. Miles, & D. G. Ahern. 1970. Mycolo^cal studies in Barataria Bay, Louisiana, and bio- degradation of oyster Spartina alterniflora. Coastal Studies Bull. 5:111-124. Penhale. P. A. 1977. Macrophyte-epiphyte biomass and productivity on an eelegrass (Zostera marine L.) community. /. Exp. Mar. Biol. Ecol 26:211-224. Pomeroy, L. R. 1959. Algal productivity in salt marshes of Georgia Limnol Oceanogr. 4.386-397. Pomeroy, L. H. I960. Primary productivity of Boca Qega Bay, Florida. BuW. Afar 5c/. IQT-IO. Russell, R. J, 1936. Physiography of the lower Mississippi Rivet Delta, Xa. State Dep. Conserv, Geol Bull 8:3-199. Sand-Jensen, K, 1977. Effect of epiphytes on eelgrass photosynthe- sis. Aquat. Bot. 3:55-63. METABOLIC ACTIVITY ASSOCIATED WITH SPARTINA 25 Stowe. W. C. 1980, Vertical distribution of epiphytic Denticuia sub- nVif Brun. Trans Am. Microsc. Soc. 99:323-328. Stowe, W, C. L982. Diatoms epiphytic pn the emergent grass Spar- Hm alrerniflora in a Louisiana salt marsh. Trans. Am. Microsc. Soc. 101:162-173. Strickland, J. D. H., & T. R. Parsons. 1968. A Practical Handbook of Seawater Analysis. Fisheries Research Board of Canada. Ottawa. 311 pp. Sullivan. M. J. 1978. Diatom community structure: taxonomic and statistical analyses of a Mississippi salt marsh. J. Phycol. 14: 468-475. Gulf Research Reports Volume 8 | Issue 1 January 1985 Soil Characteristics ofSpartina alterniflora, Spartina patens, Juncus roemerianus, Scirpus olneyi, and Distichlis spicata Populations at One Locality in Mississippi Lionel N. Eleuterius Gulf Coast Research Laboratory John D. Caldwell Gulf Coast Research Laboratory DOI: 10.18785/grr.0801.05 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Eleuterius, L. N. andj. D. Caldwell. 1985. Soil Characteristics of Spartina alterniflora, Spartina patens, Juncus roemerianus, Scirpus olneyi, and Distichlis spicata Populations at One Locality in Mississippi. Gulf Research Reports 8 (l); 27-33. Retrieved from http:// aquila.usm.edu/gcr /vol8/issl/5 This Article is brought to you for free and open access by The Aquila Digital Community It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research Reports. Vol. 8, No. 1, 27^33, 1985 SOIL CHARACTERISTICS OF SPARTINA ALTERNIFLORA, SPARTJNA PATENS, JVNCVS ROEMERIANUS, SCIRPVS OLNEYI, AND DISTfCMUS SPICATA POPULATIONS AT ONE LOCALITY IN MISSISSIPPI LIONEL N. ELEUTERIUS AND JOHN D. CALDWELL Botany Section. Gulf Coast Research Laboratory, Ocean Springs. Mississippi 39564 ABSTRACT Soil charact eristics from five adjacent monoiypic zones or different popubtions of tidal marsh plants are determined. Popubtions of Spartina alterniflora, Spartina patens, Juncus roemerianus, Scirpus olneyi, and Distkhih spicara located in Graveline Bay marshy Mississippi, are studied. Slight elevational dilTerencc-s between the plant populations exist. The aerial biomass for each pUnt population is different based on seasonal determinations. Soil pH, organic matter, N, P, K, S. Zn, Ca, and Mg concentrations arc based on analyses of seasonal composite soil samples. Analyses of soil water samples are used to determine water content, salinity, PO4 , and NH3. The soil characteristics arc highly variable within and among popubtions. Some soil properties are significantly different, while others are not. These results reflect the complex patterns in the physical and chemical soil characteristics among the salt marsh pbnt popubtions studied; however, they may not completely account for the differences in standing crop or the sharp delineation between plant zones. INTRODUCTION The occurrence of plant populations within salt marshes is controlled by varying ecological factors. The dominant ecological factors which control plant zonalions are salinity (Bourdeau and Adams 1956) and tidal inundation (Hinde 19.54); however, other factors, such as the physical and chemical characteristics of the soil, may also be important. Jackson (1952) reported on edaphic and elevational factors which affect the distribution of tidal marsh plants. The composition of salt marsh plant communities have been reported on the Atlantic and Gulf Coasts. These plant communities may be composed of two or more plant popu- lations. Adams (1963) described the composition of salt marsh corrununities of North Carolina, and Penfound and Hathaway (1938) reported on the plant communities of the southeastern Louisiana marshlands. Eleuterius (1972) and Eleuterius and McDaniel (1978) have described the marshes in Mississippi, Tidal marsh soils are very diverse along the coastline of the northeastern Gulf of Mexico, The tidal marsh soils of the Florida Gulf Coast have been studied extensively by Coultas (1978a, 1978b), and Coultas and Gross (1975, 1977), Chabreck (1972) reported on the diversity of the vegetation and the water and soil characteristics of Louisi- ana marshlands, Brupbacher et al. (J973) have also reported on the chemical properties of marsh soils in Louisiana. However, no detailed or extensive work has been done on the tidal marsh soils of Mississippi. Relationships between marsh plant communities and soils in Louisiana have been studied by Palmisano (1970), Pahnisano and Chabreck (1972) have also reported on the interrelationsMps between the chemical variables of marsli soils and the distribution of major plant species in Louisi- ana marshes. Manuscript received April 25, 1984; accepted January 7, 1985. This Study was initiated to compare the soil character- istics in one general location where monotypic stands or populations of several majortidal marsh plant species occur. Graveline Bay (Figure 1) is a closed marsh system in which the only exchange of water is through the constricted mouth of Graveline Bayou, This marsh system was selected because the salt marsh species, which form extensive mono- typic zones, are in close proximity to one another and be- cause the habitats of these various populations are approxi- mately at the same elevation. The five populations are: Spartina alterniflora Loisel., Spartim patens (Ait.) MuhL, Juncus roemerianus Scheele, spicata (L.) Greene, and Scirpus olneyi Gray. MATERIALS AND METHODS Composite soil samples were collected seasonally from each of five salt marsh plant populations in Graveline Bay marsh. Three soil samples were collected from 5 to 15 cm below the soil surface, combined, and placed in plastic bags. The samples were frozen until chemical analyses were performed by standard procedures (Black 1965). These seasonal composite soil samples were analyzed for soil pH, organic mattci content, total nitrogen (N), acid-extractable phosphorus (P), potassium (K), sulfur ($), zinc (Zn), cal- cium (Ca), and magnesium (Mg). Salinity, orthophosphate (PO 4 ), and ammonia nitrogen (NH3) analyses were con- ducted on the soil water from the seasonal composite soil samples. The soil water was removed from the soil samples by vaccuum and analyzed in the water analysis laboratory at the Gulf Coast Research Laboratory. Soil samples were also analyzed for water content seasonally from the five tidal marsh populations. Soil water content is expressed as the ratio of the mass of water present in iJie sample to the mass of the dry sample, and is presented as a percent (Black 1965). All samples were oven dried in seamless 120-ml cans at 105°C for 48 hours. Preliminary determinations 27 28 Eleuterius and Caldwell indicated that a single seasonal measurement was adequate to approximate these analyses. An analysis of variance (ANOVA) test was used to determine if a statistical difference existed among the five plant populations for each of the measured soil variables. A Duncan’s multiple range test was then used to determine which of the measured soil variables was different among the plant populations. Elevational data for the plant populations in Graveline Bay marsli were made during an extremely high tide in which the marsh surface was completely covered. Tidal height measurements were taken from the water surface to the soil surface to determine the relative elevation of the plant populations to one another. Statistical analyses were used to determine differences in elevations of the popula- tions. Three 0.125*m^ quadrat samples of the aerial portion of plants were collected seasonally from each of tlie five salt marsh plant populations. Plant material was oven dried at 105”C for 24 hours. RESULTS The standing crop values for each of the five different populations at Graveline Bay arc shown in Table 1. The winter samples are shown to have the lowest standing crop values in all plant populations. However, the greatest values TABLE 1 Seasonal comparisons of aerial dry mass values (g) of the dominant species in the five plant populations. Values represent the mean and standard error of the mean for three samples. Plant populations (species) Autumn Winter Spring Summer D. spicata 192.3 ± 2.9 167.0 ± 6.5 180.3 ± 7.0 219.3 ± 8.3 J. roemeriaims 616.2 ±25.9 490.0 ±100.3 712.0 ±21.2 579.7 ±40.5 S. alternijflora 300.2 ± 17.0 177.0 ± 18.6 245.7 ± 24.2 225.0 ±20.1 S. paiens 330.4 ± 46-2 218.7 ± 21.0 543.0 ±38.7 384.3 ±36.3 S. olneyi 219.3 ±13.7 131.7± 11.3 268.5 ±21.8 213.7 ± 4.2 TIDAL Marsh Soils 29 recorded show that peak aerial plant mass is obtained in the spring for/, roemerianus (712.0 g), S, patens (543.0 g), and 5. olneyi (268.5 g). The greatest aeriaJ biomass forD. spicata (219.3 g) is recorded in summer, and the greatest value for S. alterniflora (300.2 g) occurs in autumn. Comparison of these data clearly shows that J, roemerianus has almost twice the standing crop as S. altermflora and S. patens, and the standing crop of D. spicata is similar to that of 5. olneyi. Very little seasonal variation occurs in the A spicata popu- lation in contrast to fluctuations in the other plant popula- tions. Elevation varies in the study area from 0.0 to 7.0 cm over the entire area of the five populations and averages 2.8 cm. Comparison ofelevationaldata among the five plant popula- tions in Graveline Bay marsh discloses that the highest ele- vation is found in the D. spicata population. The diffcicnces in the elevations among the plant populations show that/ roemerianus, S. alterniflora, S. olneyi, and S. patens occur at mean elevations below the D, spicata population of only 2.1 , 2.2, 3.3, and 4.6 cm, lespectively. However, statistical analysis on the elevational data indicate that differences exist among some populations. The D. spicata population is different from all other populations (Figure 2). The popula- tions of J. roemerianus, S. alterniflora, and S. olneyi do not differ from each other; however, the results also indicate that the S, olneyi population is not different from the population of 5. patens. Soil water content varies throughout the year in relation to tidal action and precipitation. The lowest soil water con- tent values (x - 43.2%) occurred in the plant population dominated by D. spicata (Table 2) and remained relatively low throughout the year. Soil water content values from other plant populations ranged from a low of 63.5% in autumn for the S. pa tern dominated population, to a high of 22 1 .2% for the S. alterniflora population in spring. Soil water content values from the populations dominated by J. roemerianus, 5. alterniflora, S. patens, and S. olneyi. show some variation among the populations, as well as from season to season; however, there appears to be no consistent pattern except for generally lower water content values during winter. Statistical analysis on the soil water content shows that differences exist among these populations. 0 - 1 - 2 - 3 - 4 - 5 - I 6 H 7H » I I 1 1 1 2 3 4 5 PLANT POPULATIONS Figure 2. Elevation&I mean values for plant populations at Gravetine Bay marsh. Plant populations: V^Disiichlis xpieata, 2 Juncus roemer- ianus, I'Spartina atiemiflora, iSctrpus olneyi, SSparritfa patens. Vertical line Indicates 95% confidence interval. Horizontal lines over plant populations indicate significant difference (0;= 0.05) from the Duncan's multiple range lest. TABLE 2 Soil water content, salinity, orthophosphate and ammonia nitrogen taken from five salt marsh plant populations at Graveiine Bay marsh. Four seasonal values recorded for each analysis are combined and presented as die mean and standard error of the mean for the individual plant populations. Soil water content values represent the percentage of water in the soil sample on a dry -mass basis. Means in vertical columns followed by the same capital letters are not significanlly different (a = 0.05) according to Duncan’s multiple range test. Plant Populations (Species) Soil Water Content Salinity (ppt) Orthophosphate Oug-at P/L) Ammonia Nitrogen Oig-atN/L) D. spicata 43.2 ± 5.5 A 12.011.5 28.321 13.75 523.01 1 306.95 J. roemerianus 151.6 ±2L0 B 15.5 ±1.1 25.47 117.21 812.34 ±547.73 S. alterniflora 153.8±25.5 B 12.8 ±0.4 7.801 2.45 371.85 1 42.35 S. parens 100.4111.4 A,B 12.010.4 9.41 1 6.39 283.75 1 53.00 S. olneyi 113.4 ±20.0 B 12.5 ± 1.1 2.52+ 2.11 193,25 1 64.04 F • 4.655t 1.513 0.918 0.547 ♦F value from the one-way analysis of Variance. tSignificant at the 0.05 level. 30 eleuterius and Caldwell Results of the Duncan’s multiple range test indicate that the iS. patens population did not differ from the other popu- lations. However, the D. spicata population is different from the populations of J. roemerianus, S. alterniflora, and S. olneyi. Soil water salinity fluctuates in the salt marsh with the amount of tidal flooding, evaporation, and precipitation. Seasonal soil water salinity samples show minor variations among the plant populations during each season, however, there is no statistical difference (Table 2). The greatest soil water salinity values are generally obtained in the summer and the lowest values occur in the winter. Soil water salin- ity values range from 7 to 15 ppt in the/), spicata popula- tion and from 12 to 18 ppt in the J. roemerianus popula- tion. The salinities in the populations dominated by S. alter- niflora, S. patens, and S. olneyi range from 12 to 14 ppt, 1 1 to 13 ppt, and 9 to 15 ppt, respectively. Orthophosphate and ammorua nitrogen concentrations vary greatly not only among the plant populations sampled during the same season, but also among the seasons for the individual plant populations. Orthophosphate concentra- tions vary from 3.67 jug in autumn to 74.90 pg in summer for the D. spicata population and from 2.47 p% in winter to 84.93 pg in spring for the population dominated by/, roe- merianus. Concentrations in the S. alterniflora population range from 2.51 pg in winter to 15.82 pg in summer. The S. patens and S. olneyi populations range from 0.00 pg in suiTUTier to 31.12 pg and 9.83 pg, respectively, in spring. Ammonia nitrogen concentrations for the D. spicata and S. patens populations range from 53.73 pg and 161.54 pg. respectively, in summer to 1554,00 pg and 411.60 pg, respectively, in winter. The ammonia nitrogen in the popu- lations of S. alterniflora and S. olneyi ranges from 261 .96 pg and 34.58 pg, respectively, in spring to 478.00 in winter for S. alterniflora and 392.08 jug in autumn for 5. olneyi. The ammonia nitrogen in the /. roemerianus population ranges from 122.64 pg in summer to 2706,25 pg in autumn. Although the variations in PO 4 and NHa are large, there are no statistical differences (Table 2). No statistical differences are indicated by the ANOVA test among the plant populations for the soil elements K, S, Zn, Ca, and Mg (Table 3). However, there is a difference among the plant populations for the variables pH, N, P, and organic matter content. Soil pH values are greater in the D. spicata plant popula- tion than in all other populations. Statistical comparison of the Z). spicata population to all others shows it to be dif- ferent. The populations of J. roemerianus, S. patens, and S. alterniflora are similar in soil pH and do not differ statis- tically. However, the soil pH values of the S. alterniflora population are also similar to those in the population of*S. olneyL And the values of these two populations are not statistically different, The range and mean pH values are shown in Table 3, along with the statistical relationships between the five plant populations. Total nitrogen concentrations and the amount of organic matter in the soils are considerably lower in the D. spicata population than in all other plant populations. Phosphorus concentrations in the D. spicata population are greater than concentrations in the /, roemerianus population and the TABLE 3 Chemical characteristics of composite soil samples taken from live salt marsh plant populations at Giaveline Bay marsh. The four seasonal values recorded for each soil analysis were combined and presented as a mean and standard error of the mean for the individual plant population. Mean-s in vertical columns followed by the same capital letters are not significantly different {a= 0.05) according to Duncan's multiple range test. Range values are in parenthesis. Plant Populations (species) pH Organic Matter (%) N (ppm) P (ppm) K (ppm) S (ppm) Zn (ppm) Ca (ppm) Mg (ppm) D. spicata (7.4-7.7) 3.9 A 1446 A 189 A 2854- 300+ 5.19 1616 1420 7.5 A iO.l ±0.4 ±133 ±24 ±0 +0 ±0.74 +230 +113 J. roemerianus (5 .7-6.2) 9.7 B 4574 B 133 B 285+ 300+ 5,69 1372 2694 6.0 B ±0.1 ±0.9 +858 ±11 ±0 ±0 ±0.89 ±225 ±465 S. alterniflora (4.6 -6,4) lO.l B 4494 B 74 C 285+ 300+ 6.81 1044 2167 5.6 B,C ±0.4 ±0.5 ±529 ±5 ±0 ±0 ±0.48 ±143 ±305 S. patens (5 .5 -6.9) 10.4 B 4204 B 76 C 285+ 300+ 7.73 1084 2106 6.0 B ±0.3 ±0.2 ±522 ±2 +0 ±0 ±0.67 ±66 +92 S. olneyi (3.7-6.3) 8.7 B 4089 B 67 C 285+ 300+ 7.48 1080 1948 4.8 C ±0.5 ±1.3 +986 ±3 +0 ±0 ±0.54 ±208 ±371 ^(4,15) 8.767t 12.376t 3.76lt 17.835t 0.000 0.000 2.650 1.794 2.230 t Significant at the 0.05 level. Tidal Marsh Soils 31 concentrations of phosphorus in the soils of these two popu- lations are greater than those of the areas supporting tlte other plant populations. The populations of S. patens, S. alterniflora, and S. olneyi do not differ from each other in the concentration of soil phosphorus. No differences in soil sulfur and potassium concentrations axe found among the five plant populations. The concentrations for the soil ele- ments Mg,Ca,and Zn show variation among the plant popu- lations, although no statistical differences are noted. DISCUSSION Variations in the soil properties of salt marshes have been studied along the Gulf toast in Florida (Coultas and Gross 1977) and Louisiana (Chabreck 1972); however, the soils of the marshlands of Mississippi have not been ade- quately surveyed. Plant zonation in salt marshes has been studied along the Atlantic and Gulf coasts; however, tl'ie relative importanee of different environmental factors, sueh as salinity, tides, elevation, and soil characteristics affecting the zonation in sail marshes is unclear. For example, some studies indicate that elevation may be the cause for plant zonation (Harshberger 1911, Johnson and York 1915, Reed 1947, Hinde 1954). However, Eleuterius and Eleuterius (1979) indicated that other factors, such as soil water salinity, may be involved, which are superimposed on the elevation-tide level rclationsliip. Jackson (1952), Kurz and Wagner (1957), Adams (1963), and Shiflet (1963) indicated that soil water salinity was the primary factor affecting plant zonation in tidal marslies. Furthermore, Gillham (1957), Beeftink (1966), and Ranwell (1972), have observed inver- sions of zonation to tidal submergence. These reports and the present study, where no differences in soil water salin- ity are found among populations, indicate that perplexing relationships exist among plant zonation, elevation, and tidal submergence. Palmisano (1970) and Palmisano and Chabreck (1972) have reported on the relationship between the soils and plant communities in Louisiana marsldands and no consistent relationships between soil nutrients and vegelational type were found. Considerable overlaps were observed in nutrient concentrations among vegetational types. Canning and Eleuterius (1978) showed that the silica content of soils from four populations of /. roemerianus was different. The Graveline Bay marsh plant populations studied are predominantly pure stands of the salt marsh species. The 5. oimyi stand is a pure stand ; however, occasional plants of D. spicata are found intermixed with / roemerianus. A few plants of Borrichia frutcscens are found around the edge of the D. spicata stand. The S. alterniflora stand con- tains an occasional plant of Spartlna cynosuroides. The S. patens stand is pure. The fluctuations in the aerial plant mass during the seasons are considered to be typical of the respective salt marsh plant species. In late summer, D. spicata reaches maximum aerial mass; J. roemerianus, S, patens, and S. olneyi each reach maximum aerial mass in spring; and S. alterniflora has the greatest aerial mass in autumn. Results presented here show little variation in the eleva- tion among plant populations in Graveline Bay marsh; how- ever, D. spicata occurs at the highest elevation and S. patens occurs at the lowest elevation, with/, roemerianus, S. aiter- niflora, and S. olneyi occurring at approximately the same elevation. These data indicate that there are elevational dif- ferences among the five plant populations, but aU of the populations only span an average range of 4.6 cm. Soil water content values are consistently lower in the D. spicata population, when compared seasonally to the other plant populations. Soil water content values for the other plant populations seem to be similar to one another, al- though variations occur among seasons and populations. Soil water content and organic matter appear to be related to marsh elevation. The lowest water content and lowest amount of organic matter are found in the D. spicata popu- lation, which occurs at the higliest elevation. The seasonal soil water salinity values show only slight variations of less than 6 ppt among the plant populations. However, the soil water salinities are generally lower in winter and higher in summer. Although the soil water salin- ity values vary, there are no appreciable differences among the five plant populations. Orthophosphate and ammonia nitrogen concentrations from the soil water show seasonal variations for each plant population and also show a wide range of differences among plant populations for individual seasons. Allhougli the soil pH values found in the plant popula- tions range from 3.7 to 7.7, they are typical for tidal marsh soils and correspond closely to those reported by Chabreck (1972). The percent of soil organic matter varied widely among the plant populations studied, Boyd (1970) showed that there was a correlation between soil organic matter content and soil nitrogen for aquatic plant habitats. This relationship was also found in the present study, where lower organic matter content in the soil corresponds to lower soil nitrogen concentration. The D. spicata popula- tion has the lowest mean amount of organic matter in the soil and the populations of S, patens and 5. alterniflora have the greatest mean organic matter values. The mean total nitrogen concentration in the soil is considerably less in the D. spicata population than in other plant populations studied. Although the soil organic matter varied among the populations of 7. roemerianus, S. alterniflora, S. patens, and S. olneyi, they all have similar soil total nitrogen concentra- tions. Brupbacher et al. (1973) reported large variations in phosphorus from the marsh soils of Louisiana . In the present study, soil phosphorus concentrations represent a wide range of values among the plant populations, but these con- centrations are within the ranges of those reported by Brupbacher et al. (1973). Thei7. spicata population has the greatest soil phosphorus concentration and 5, alterniflora, 32 Eleuterius and Caldwell S. patens, and S. olneyi populations are considerably less. DeLaune and Patrick (1980) stated that nitrogen was more imporlant than phosphorus to plant growth in Louisiana marshes. Brupbacher et al. (1973) reported large variations in Ca and Mg for the marsli soils in Louisiana, however, our results show only slight variations. Dunstan and Windom (1975) have reported zinc concentrations in marsh sediments on the Atlantic Coast ranging from 14.9 to 69.6 ppm. We found the greatest mean concentrations of Mg in the J. roe- merianus population and the lowest mean concentrations in the population of D. spicata. For the element Ca, the D. spicata population has the greatest mean concentrations and the .S. alternifiora population the lowest. In the present study, soil concentrations of the element Zn show only a small range from a mean high of 7.73 ppm in the 5. patens population to a low of 5.19 ppm in the D. spicata popula- tion. Boyd and Hess (1969) showed that an increase in soil nutrients increased shoot production of Typha latifolia. The five plant species reported upon in the present paper are represented by different standing crops. Biomass de- pends largely on the peculiar vegetative morphology of each species. Although our results reflect some differences in physical and chemical soil characteristics among the five salt marsh plant populations, their role in the sharp delinea- tion between plant zones remains unknown. It should also be pointed out that the vegetational composition of the area studied here is not characteristic of all marshes in Mississippi. The Graveline Bay marsh is unusual in having five different kinds of plant populations present adjacent to one another. However, the study clearly shows that the five plant species can and do form populations on intertidal areas with similar soil characteristics and tliat they are capable of occupying the same terrain in some locations. acknowledgments We thank other members of the Botany Section of the Gulf Coast Research Laboratory for assistance with various aspects of this study. Special thanks are due to Helen Gill and Cindy Dickens for typing the manuscript and to Linda Laird who inked the illustrations. REFERENCES CITED Adams, D. A. 1963. Factors influencing vascular plant zonation in North Carolina salt marshes. Ecoh^ 44(3);445-456. Becfiink, W. G. 1966. Vegetation and habitat of the salt marshes and beach plains in the southwestern part of the Netherlands. Wfnlia 15:83-108. Black, C. A. (ed ). 1965, j\ferhods of soil analysis. Part 1, II. Amer. Soc. of Agron., Inc. Madison. Wisconsin. 1569 pp. Bourdeau, P. F, & D. A. Adams. 1956, Factors in vegetational zona- tion of salt marshes near SouthpoK, N.C. Bull. Ecoi Soc, Am. 37(31:68, Boyd, C. E, 1970, Influence of organic matter on some characteris- tics of aquatic soils. 36<1):17-21. & L. W. Hess. 1969. Factors influencing shoot production and mineral nutrient levels irt Typha laiifoUa. Ecology 51(2): 296-300. Brupbacher. R. H., J. E. Sedbetry. Jr. & W. H. Willis. 1973. The coastal marshlands of Louisiana. Chemical properties of the soil maletuls-lff. Agric. Egp. Stn. Bull. No. 672. 34 pp. Chabreck, R. H. 1972. Vegetation, water and soil characteristics of the Louisiana coastal region. La. Agric. Exp. Stn. Bull No. 664. 72 pp. Coultas, C. L. i978a. Soils of the intertidal marshes of Dixie County, Florida. Fk. Set 41(2):81-90. 1978b. The soils of the intertidal zone of Rookery Bay, Florida. SSSA (Soil Set. Soc, Am.) Spec. Publ. Ser. 42(1); 111^115. ^ &. E. R. Gross. 1975. Distribution and properties of some tidal marsh soils of Apalachee Bay, Florida. (SoilScL Soc. Am.) Spec. Publ. Ser 39(5):914-919. &. E. R. Gross. 1977. Soil section. Tidal marsh soils of Florida's middle Gulf Coast. Soil Crop Set Soc. Pi. Proc. 37: 121-125. DeLaune, R. D. & W. H, Patrick, Jr. 1980. Nitrogen and phosphorus cycling in a Gulf Coast salt marsh. Pages 143-151 in: V. S. Kennedy (ed,). Estuarine Perspectives. Academic Press, Inc., New York.N.Y. Dunstan, W. M. & H, L. Windom. 1975. The influence of environ- mental changes in heavy metal concentrations on Spartina alterni- fhra. Pages 393-405 nt. L. E. Cronin (ed ), Esfuarme Rfs. Vol. II. Academic Press, Inc., New York, N.Y. Eleuterius, L. N. 1972. Marshes of Mississippi. Castartea 37:153- 168. A S. McDaniel. 1978. The salt marsh flora of Mississippi. Castanea 43:86-95. & C. K. Eleuterius. 1979. Tide levels and salt marsh zona- tion. Bull. Mar. Sci. 29(3):394-400. Gillham, M. E. 1957. Coastal vegetation of Mull and Jona in relation to salinity and soil reaction. / Ecol, 45:151 -llS. Harshbeigei, J. W. 1911. An hydromeitic investigation of the in- fluence of sea water on the distribution of salt marsh and estu- arine plants. Am. Philos. Soc. .50(201 ):457— 496. Hinde, H. P. 1954, 'fhe vertical distribution of salt marsh phanero- grams in relation to tide levels. EcoL Monogr. 24:209-225. Jackson, C. R. 1952. Some topographic and cdaphic factors affect- ing distribuiion in a tidal marsh. (J. /. Fla. Acad. Sci. 15:137- 146. .Tohnson, D. S. & H. H. York. 1915. The relation of plants to tide levels. A .study of factors affecting the distribution of marine plants. Carnegie Jnst. Wash. Publ. No. 206. 162 pp. Kurz, H. & K. Wagner. 1957. Tidal marshes of the Gutf and Atlantic coasts of northern Florida and Clrarleston, South Carolina. Fla. State Univ, No. 24. 168 pp. Canning, F. C, & L, N, Eleuterius. 1978- Silica and ash in the salt marsh Juncus roemerianus. Gulf Res. Rept. 6(2): 169- 172. Palinisano, A. W, Jr. 1970. Plant community-soil relationships in Louisiana coastal marshes. Dissertation. La. State Univ, and Agii. and Mcch. College, Baton Rouge, La, University Microfilms. 98 pp. & R. H. Chabreck. 1972. The relationship of plant com- munities and soils of the Louisiana coastal marshes. Presented at 13th annual meeting l.outsiana Association of Agronomists. Lake Charles, Louisiana. March, 1972. Penfound, W. T. & E. S. Hathaway. 1938. Plant communities in the marshlands of southeastern Louisiana. Ecol. Monogr. 8:1 -56. Tidal Marsh Soils 33 Ranwell, D. S. 1972, Ecology of salt marshes and sand dunes. Chapman and Hall, London. 258 pp. Reed, J. F. 1947. The relation of the Spar tinet urn glabrae near Beaufort, North Carolina, to certain edaphic factors. Am. Midi. Nat. 38:605-613. Shitlet, T. 1963. Major ecological factors controlling plant commu- nities in Louisiana marshes./. Range Manage. 16:231-234. Gulf Research Reports Volume 8 | Issue 1 January 1985 Notes on Barnacles (Cirripedia: Thoracica) from the Gulf of Mexico Stephen R. Gittings Texas A6’M University DOI: 10.18785/grr.0801.06 Follow this and additional works at; http://aquila.usm.edu/gcr Part of the Marine Biology Commons Recommended Citation GittingS; S. R. 1985. Notes on Barnacles (Cirripedia: Thoracica) from the Gulf of Mexico. Gulf Research Reports 8 (l): 35-41. Retrieved from http://aquila.usm.edu/gcr/vol8/issl/6 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(Dusm.edu. Gulf Research Reports. Vol. 8, No. 1, 35-41 , 1985 NOTES ON BARNACLES (CIRRIPEDIA: THORACIC A) FROM THE GULF OF MEXICO STEPHEN R. GITUNGS Department of Oceanography, Texas A&M University College Station, Texas 77843 ABSTRACT Examination of several collections of barnacles from the northern and western Gulf of Mexico made over the last 30 years has improved our knowledge of the distributions of several taxa previously considered to be absent or rare in those regions. Conchoderma auritum (Linnaeus) and Her era lepas sp. aff. cornuia (Darwin) arc recorded for the first time from the Gulf of Mexico. Conchoderma auritum, Conchoderma virgatum (Spengler), Heteralepas cornuta (Darwin), Balanus trigonus (Darwin), Balanus venusrus Darwin, and Balanus amphitrite amphiirite Darwin have broad distributions outside the Gulf of Mexico. Teiraclita stalactifera stalactifera (Lamarck) is abundant in the intertidal zones of the south- western Gulf, but rare elsewhere in the Gulf of Mexico outside the Florida Keys. Spatial segregation of Octolasmis hoekl (Stebbing) and Octolasmis iowei (Darwin) on a host ciab is discussed. INTRODUCTION The purpose of this paper is to present information on the diatiibution of nine barnacle species in the Gulf of Mexico, based on an examination of the barnacles from regional museum collections. Two new records of barnacles for the Gulf of Mexico are presented: the lepadomorphs, Conchoderma auritum (Linnaeus), a pedunculate barnacle often attached to whales, and Heteralepas sp. aff. cornuta (Darwin). Heteralepas cornuta has been found attached to the stems of gorgonians and to other organisms below 90 m depth (Weisbord 1979). Species not previously known from the western Gulf of Mexico include Conchoderma virgatum (Spengler), a widely distributed, pelagic lepadomorph attached to various organisms and floating objects, Tetra- clita stalactifera stalactifera (Lamarck), an intertidal balano- morph (often called “acorn” barnacles), and Balanus trigonus (Darwin), a subtidal balanomorph with a wide distribution. A review of the literature suggests that two intertidal and subtidal balanids documented herein from the northwestern Gulf, Balatuis amphitrite amphitrite Darwin and Balanus venustus Darwin, may have been long overlooked or misidentified in the past. Finally, an exam- ination of specimens of two crab-dwelling barnacles, Octolasmis hoeki (Stebbing) and Ocfolasmis lowei (Darwin), on Calappa sulcata Rath bun (Brachyura; Oxyslomata) indicates the two species are spatially segregated on the body of this host. The Gulf of Mexico is a semi-enclosed oceanic basin extending from approximately 18®N to 30°N and to 97°W on the western side of the Atlantic Ocean. Water enters the Gulf through the Yucatan Channel (176 km wide) and exits througli the Florida Straits (144 km wide). The Loop Current, which directs iliis flow, is restricted to the eastern Gulf. The northward extent of the Loop Current varies considerably, typically ranging further north during the summer (Ichiye et al. 1973; Figure 1), There are several important differences tliat distinguish Manuscript teceived April 30, 1985: accepted June 24, J985. the western Gulf of Mexico from the eastern Gulf. First, with respect to circulation, the tropical waters of the Loop Cuirent influence the western Gulf of Mexico much less than they do the Gulf east of the Mississippi River delta. Second, though the continental shelves off Florida and the Yucatan peninsula consist of carbonate sediments, the shelf in the northwestern Gulf consists of terrigenous sediments, which results in much higher turbidity (Rezak et al. 1983; Figure 1). Third, the influence of winter cold fronts on nearshore surface water temperature is most pronounced in the northwestern portion of the Gulf of Mexico (Rezak ct al. 1983), Nearshore surface temperatures off Louisiana may be as low as 6®C for short periods in winter. Fourth, salinity in these same waters is strongly influenced by variability in the Mississippi/ Atchafalaya discharge system and other rivers draining into the northwestern Gulf (Rezak et al. 1983). Most of the Mississippi River discharge flows west along the coast of Louisiana (Figure 1). Thus, the hydrography of the western Gulf of Mexico is very different from lhat of ihc eastern Gulf, especially in the northwest- ern region, where terrigenous sediments and highly variable salinity and temperature regimes predominate. Of the nine species discussed herein, Teiraclita stalactifera stalactifera, Balanus trigonus and B. a. amphitrite show regional differ- ences in distribution and abundance that appear to be related to the above parameters. Few barnacle collections made in the western Gulf of Mexico had been analyzed until recently. This was, in part, due to the lack of cirriped specialists in the region. Addi- tionally, the lack of natural hard substrates has limited the number of cirriped collections in the northwestern Gulf of Mexico. It has been only in the last several decades that inan-made Jiard substrates (e.g., jetties, oil rigs) have allowed tlie development of any substantial intertidal and subtidal fouling communities. Comparisons of present day biofouling community species composition with that from two to three decades ago suggest the region is still under- going successional changes (Gunter and Geyer 1955, George and Thomas 1979). 35 36 Gittings Figure 1. Map of the Gulf of Mexico summarizing circulation patterns, continental shelf bottom types, and tuibid water regions. Anows representing Loop Current show range of variability in flow pattern. Nearshore circulation patterns are not illustrated. Spin-off eddies repre- sent mechanisms for dispersal of tropical organisms to continental shelf regions in both the eastern and western Gulf of Mexico. (Modified, with permission, from Rezak et al. 1983). Most Other collections from the western Gulf of Mexico included either deep-sea species or those epizooic on organ- isms collected for other studies. These collections include primarily trawl samples made by the M/V OREGON (1961-1968), the R/V OREGON M (1967-1977), the R/V ALAMINOS (1963-1973), and the RfV GYRE (1974 to present). Spivey (1981) summarized the available information on the zoogeography of the Cirripedia of the Gulf of Mexico and provided a list of species occurring in the region. Based in part on the relatively low endemisin of cirripeds (14%) and other invertebrate groups, and the wide overlap of temperate and tropical species, he determined that the Gulf of Mexico is a transition zone between tropical and warm temperate shelf faunas. Abbreviations for collections reported herein are as follows: CeSU - personal collection of Dr. J. W. Tunnell, College of Science and Technology. Corpus Christi State University, 6 3(X) Ocean Drive, Corpus Ch/isli, Texas 78412; GCRL - Gulf Coast Research Laboratory, Ocean Springs, Mississippi 39564; TAMU- Texas A&M University System- atics Collection, Dept, of Oceanography, College Station, Texas 77843; TAIU -Texas A&! University, Biology Dept., Kingsville, Texas 78363; UTMSI - University of Texas Marine Science Institute, Port Aransas, Texas 78373. SYSTEMATICS Order THORACIC A Darwin, 1854 Suborder LEPADOMORPHA PUsbry, 1916 FamUy LEPADIDAE Darwin, 1851 Conchoderma auritum (Linnaeus, 1767) Gulf of Mexico - GCRL77:1075: from plastic band on head of dusky shark, Carcharinus obscurus (Lesueur); about 16 km south of Pensacola, Florida; 21 July 1977; coll. T. Mattis; det.W. A. Newman. Barnacles of the gulf of Mexico 37 Remarks — This record represents the only account of this species in the Gulf of Mexico, This occunence was first presented, without collection data, by Overstreet (1978). Zullo (1979) considered C auritum to be a cosmopolitan species, often found attached to whale barnacles and, occasionally, to ships. This species has also been found attached to the teeth, baleen, palate, and penis of whales (Dr. H. R. Spivey, Florida State University at Tallahassee, pers. comm.). The nearest record to the Gulf of Mexico is from Cape Hatteras, North Carolina, on an iron buoy (Weisbord 1979). Conchoderma vir^tum (Spengler, 1790) Northwest Gulf of Mexico - Attached to gray trigger- fish, Batistes capriscus Gmelim, found in sediment trap; south of Mobil oil platform (lease block HI-389), near East Flower Garden Baii, 27®54'N, 93^36'W; 5 February 1983; coll. L. S. Baggett. Remarks - Published records (Wells 1966, Pequegnat and Pequegnat 1968, Dawson 1969) and unpublished records (GCRL68:8U, GCRL72;1055) suggest that this species is common in the eastern Gulf of Mexico on floating objects and various marine organisms (also see Spivey 1981). Conchoderma virgatum is a cosmopolitan species found attached to ships, buoys, fish, parasitic copepods, etc. (Zullo 1979). Its occurrence off the northwestern Gulf coast, therefore, is not surprising. Family HETERALEPADIDAE Nilsson -Cantell, 1921 Heteralepas sp. aff. comuta (Daiwin, 1851) (Figure 2a) Gulf of Mexico - GCRL67;750: 20 specimens on anti- patharian; 29°15'N, 88®11'30"W, Offshore project Station 6; 92 m; 15 March 1967; coll. R/V GULF RESEARCHER. Remarks - Dr. Victor Zullo (University of North Caro- lina at Wilmington, pers. comm.) found //. cornu ta in the mid-1960's to be abundant on settling plates (several hun- dred individuals) from off Fort Lauderdale, Florida. Else- where in waters adjacent to the Gulf of Mexico, the species is known from off Cape Lookout, North Carolina (91 m depth, Ross 1964). It has also been found at several loca- tions in the eastern Atlantic (Weisbord 1979), in the Indian Ocean (Nilsson-CanteU 1938), and at one location in the eastern Pacific (Ross 1975). Ross (1975), however, sug- gested that those reported from the Indian Ocean may be referable to H. japonica (Aurivillius), a closely related species. Collection depths range from 90 m to 4315 m. The above record represents the only report of this genus and species from the Gulf. The specimens examined differ somewhat from H. cornuta, described originally by Darwin (1851) from St. Vincents, West Indies, and from those examined by Ross (1975) from the eastern Pacific, in the number of segments comprising the rami of the 5th and 6th cirri and the caudal appendages. The posterior (rudimentary) rami of the Gulf of Mexico specimens have between 8 and 1 1 seg- ments and the anterior rami have 42-46 segments. Caudal appendages contain 6 segments. For this species, Darwin indicated between 11 and 13 segments for the posterior rami, although a ramus of 8 segments is illustrated (his Plate X, Figure 28), 63 segments for the anterior rami of the 6th cirri and 8 for the caudal appendages. Ross (1975) indicated 12 to 15 segments for the posterior rami, 52 to 53 segments for the anterior rami, and 9 segments for the caudal appendages. Without comparisons to other material, I chose not to assign the present specimens to//, comuta. It is, however, likely that segment number varies in //, cornuta, based on comparisons of descriptions by Darwin (1851), Broch (1927) and Ross (1975). Segment number is known to vary considerably in a closely related and better known species, H. japonica (Aurivillius 1894, Foster 1978). Family POECILASMATIDAE Nilsson -Cantell, 1921 Octolasmk hoeki (Stebbing, 1895) (Figure 2b) Octolasmis lowei (Darwin, 1851) (Figure 2c) Synonymy of local occurrence for Octolasmis lowei: Octolasmis mulleri (Coker): Pilsbry 1907, pp. 95-96, fig. 32c;Pearse 1952, p. 238;Hulings 1961, p. 216. Western Gulf of Mexico - O. hoeki: TAMU-2-6487: 12 on epipods of 3rd maxillipeds of Calappa sulcata Rathbun; 28'^19'N,95°23.8'W;38 m;4 June 1971; coll. R.M. DarneU. - O. hoeki: TAMU-2-6489: 19 on epipods of 3rd maxillipeds of Calappa sulcata, with Octolasmis lowei; 23°58.4'N, 97°29.5'W; 37 m, 24 September 1971; coU. R. M. Darnell. - O. lowei: TAMU-2-6488: 23 inside gill chamber of Calappa sulcata; 28"40.7'N, 94®47.rW; 22-27 m, 7 July 1972; coll. W. E. Pequegnat. - O. lowei: T AMU-2-6490: inside gill chamber of Calappa sulcata, with Octolasmis hoeki; 23°58.4'N, 97®29.5'W; 37 m; 24 September 1971; coU. R. M. DarneU. Remarks - Octolasmis lowei is known to occur in the gill chambers of several crab species (Pilsbry 1907, Pearse 1952, Wells 1966, Jeffries et al. 1984) and is considered to be a cosmopolitan spepies (Causey 1961). It has not, how- ever, been reported from the eastern Pacific (Weisbord 1979). Octolasmis hoeki, a tropical to north temperate Atlantic species (Spivey 1981), has been found “on the sub- branchial region of Calappa flammea*' (Hulings 1961) and on the mouthparts of palinurids (Stebbing 1895, Gruvel 1905). Wells (1966) incorrectly paraphrased Hulings (1961), saying 0. hoeki was found “in” the branchial chamber of C. flammea. Co-occurrence of these species on the same host has been noted by Causey (1961). I have found both species on several large specimens of C. sulcata from the 38 Gittings 1.0 mm Figure 2. Lateral views of: (k) ifetenlepas sp. aff. comuta (Darwin); (b) Octolasmis hoeki (Stebbing);{c) OctoUumis lowei (Darwin). western Gulf of Mexico. Data from one crab are given above (T AMU-2 -6489 and TAMU.2.6490). Never were both species found to occur together on the same body region of a crab. There is a clear spatial segregation between 0. lowei within the branchial chambers of C sulcata (on the gills and in the gill chambers) and O. ftoeki outside the chambers (on the mouthparts, the carapace near tJie gills, and on the exo- skeleton of the first walking legs near the branchial cham- ber). These spatial preferences are evident even in cases where only one species is present. Suborder BALANOMORFHAPUsbry, 1916 Family TETRACLITIDAE Gruvel, 1903 Tetraelita stalactiferv stalaciifera (Lamarck, 1818) Synonymy of local occurrence: Tetraclita squamosa stalactifera Lamarck: Stephenson and Stephenson 1950, p. 388; Henry, 1954, p. 444. Western Gulf of Mexico - UTMSI: 1 individual from jetty, Tuxpan, Mexico, 2l“00'N, 97“l5'W; intertidal, with Chthamalus fragilh Darwin; 24 December 1954; coll. H. H. Hildebrand. — UTMSI: from Boca Andrea, Veracruz, Mexico, 19® 15'N, 96®08'W; no date; coU. H. H. Hildebrand. - CCSU: 6 individuals; Isla de Lobos, Mexico, 21®27'N, 97® 15'W; station 1-7-4; 7 June 1973; coU. J. W. Tunnell. - CCSU: 1 individual; Isla de Lobos, Mexico, 2r27'N, 97®15'W; windward reef, south side,4£.TO^orff zone, 1,5 to 4,5 m; station 76-14-1; 14 June 1976; coll. J. W. Tunnell. — CCSU: 13 individuals; Isla de Lobos, 21°27^N, 97®15'W;.r4crc;porj zone, west of boulder ridge on leeward Barnacles of the Gulf of Mexico 39 side of island, 1 to 3 m; station 76-14-2; 14 June 1976; coll. J.W.TunneU. — TAMU, uncataloged: 4 individuals, the largest 3.5 cm carino-rostral length, with Balanus reticulatus Utinomi and Megahalanus aniillenm (Pilsbry); Mobil oil platform (lease block HI-389), 2 km soutireastof East Flower Garden Bank, 27°54'N, 93°36^W; near surface; 26 March 1984, R/V GYRE cruise 84-G-3; coE. G. D. Dennis, Remarks - Tetraclita stalactifera stalactifera is found intertidally in the western Atlantic from Florida to Brazil (Southward 1975). Newman and Ross (1976) also list the species from Bermuda, the Gulf of California south to Acapulco, Mexico, the Arabian Sea, and South Africa. These are the only records of this species in the Gulf of Mexico outside the Florida Keys (see Stephenson and Stephenson 1950, Henry 1954), and the Yucatan peninsula (Spivey, pers. comm.), and support, in general, Southward’s (1975) conclusion that the distribution of T. s. stalactifera is intertidal in relatively clear waters. This species has not been found on any natural or man-made structures in the turbid nearshore waters of the northern Gulf of Mexico, It is apparently common in Mexican waters north to at least Cabo Rojo. It is not known from north of Cabo Rojo in tlie Gulf, except from the oil platform near the East Flower Garden Bank, approximately 177 km SSE of Galveston, Texas. The water near this shelf-edge bank is very clear and temperatures are always above 18®C. In the southwestern Gulf, T. s. stalactifera has been found attached to both arti- ficial and natural substrates, including the dead portions of storm-tossed Acropora palmata (Lamarck) branches and coral heads on the cre.sts of coral reefs (Dr. J. W. Tunnell, Corpus Christi State University, pers. comm.). Family BALANIDAE Leach, 1817 Balanus trfgonus Darwin, 1854 Northwest Gulf of Mexico - TAMU, uncataloged: on plastic recruitment floats; 10 km south of Holly Beach, Louisiana; settled between June and August 1982 and Sep- tember to October 1983 (Gittings 1984 and unpublished data, respectively), with Balanus reticulatus, B. improvisus Darwin and B. ebumeus Gould; 8-10 m; coll. S. R. Gittings. - UTMSI: 22 live, 9 dead, on Busy con, 17 live, 5 dead, on another Busy con, in trawl; Redfish Bay, near Port Aransas, Texas; 3 m; 22 April 1984; coU. R. D. Kalke. - TAMU, uncataloged: on Crassostrea virginica (Gmelin), with B. ebumeus; Aransas Bay, Texas, near causeway from Port Aransas to Aransas Pass; salinity 31 ppt;27®C;0.6 m; 21 September 1984; coll. S. R. Gittings. - TAMU, uncataloged: abundant on seaward end of rock jetty, sub tidal to 6 m depth, with Megabalanus antillensis, Chthamalus fragilis, and Balanus amphitrite amphitrite; also on gorgonians; Port Mansfield, Texas; 13 August 1984; coll. S. R. Gittings. — TAMU, uncataloged: on bay scallop, Argopecten irradians (Lamarck); Laguna Madre, Texas, near spoil island just south of Mansfield Channel; 0.5 m; 13 August 1984; coll. S. R. Gittings. — TAMU, uncataloged; on terra cotta recruitment plates and PVC support structure 1 m above live coral reef (Mr. L. S. Baggett, Texas A&M University, pers. comm.), settled 1982-1983; East Flower Garden Bank (27''54'N, 93°36'W);21 m; coll. L. S. Baggett. Remarks - Is is surprising that B. trigonus has not been reported until now from the western Gulf of Mexico, since it is cosmopolitan in waim seas and its distribution, for the most part, is natural (i.e., unaltered by man’s activities; Newman and Ross 1976). I have found it to be quite abun- dant and widespread in both turbid and clear waters off Texas and Louisiana, althougli it is seldom a principal fouler of stationary structures. Perhaps, as suggested by Wells (1966), B. trigonus has within the last several decades been extending its range. Hedgpeth (in Whitten et al. 1950) thought “5. amphitrite niveus ... is probably the species seen covering rocks below the Chthamalus fragilis zone at the end of the [Port Aransas, Texas) jetty” (p. 76). The balanid material of Whitten et al., althougli not available for study, may be referable to B. trigonus, which I have seen occupying an identical position on the Port Mansfield (Texas) jetty. The distribution of B. trigonus in Texas bays may be limited by high water temperatures during the summer. Ritz and Foster (1968) found that cirral activity for B. trigonus living in an area with a temperature range of 11— 21‘’C increased to a temperature optimum of 27®C, with cessation of activity at 31®C. In Texas bays, summer water temperatures may exceed 32° C. Balanus amphitrite amphitrite Darwin, 1854 Northwest Gulf of Mexico - CCSU: Corpus Christi Bay, Texas, north beach under harbor bridge; with Balanus ebumeus; salinity 27 ppt;16°C;7 February 1980; coll. J. W. Tunnell, — TAMU, uncataloged; 3 on Scotch Bonnet sliell, Phalium granulatum (Born), with Balanus ebumeus; Red- fish Bay, Texas; <1 m depth; February 1984; coll. T. J. Bright. — TAMU, uncataloged; 6 live, 30 dead, from public boat ramp; Port Mansfield, Texas, mainland side of Laguna Madre; intertidal; 24 February 1984; coll. T. J. Bright. — UTMSI: abundant on samples of serpulid reef from Baffin Bay, Texas; approximately 1 m depth; no date . — TAMU, uncatalogod: 11 live, 5 dead, on oysters, Crassostrea virginica; Redfish Bay, Texas, oyster reef near causeway from Port Aransas to Aransas Pass, Texas; with Balanus reticulatus (dead) and Balanus eburneus; 23 March 1985; coll. M.K.Wicksten. Remarks - Balanus amphitrite amphitrite has a cosmo- politan distribution in warm seas (Newman and Ross 1976). The occurrence of this species intertidally on pilings and rocks at Corpus Christi Bay Beach, Corpus Christi, Texas, 40 Gittings was noted in 1971 by Spivey (pers. comm.). Wells (1966) and Henry and McLaughlin (1975) reported its presence to the east, off Panama City, Florida, and to the south, off Veracruz, Mexico, but cited no localities in the northwest- ern Gulf of Mexico. Though Hedgpeth (in Whitten et al. 1950) reported B. a. niveus from the Port Aransas, Texas, jetties, and Gunter and Geyer(1955) reported amphitrite from platforms off Texas and Louisiana, it is not clear whether their specimens were B. a, amphitrite, B. reticu- latus, B, venustus (with which B. a. niveus was later syn- onymized; Harding 1962), or, perhaps, even B. trigonus, as discussed previously. Thomas (1975) suggested that B. a. niveus reported by Whitten et al. (1950) was B. venustus. Though B. venustus occurs in the western Gulf of Mexico, it is not common, and it is doubtful that it occurs at any time on jetties in abundances seen by Whitten et al. (1950). Balanus trigonus is the only species I have seen to occur in abundances reported by Whitten et al. (1950) on the ends of (south) Texas coast jetties. Analysis of recent collections suggests that B. a. amphi- trite is a common species, though not in liigh abundance, on man-made structures in shallow south Texas bays. It is less frequently observed in the more northern bays. Personal collections have not confirmed B. a. amphitrite on any off- shore oil structures or artificial settling substrates in the northwestern Gulf of Mexico, These are occupied predom- inantly by B. reticulatus nearshore in the northern Gulf (Thomas 1975) and by Megabalanus antillensis, B. trigonus, andiJ. reticulatus on offshore and south Texas structures. Balanus venustus Darwin, 1854 Northwest Gulf of Mexico - TAIU: approximately 24 on shell dredged from IVi Fathom Reef, 26®5l'N, 97®18'W, north of Port Mansfield, Texas; 27 July 1973. — TAMU, uncataloged: about 25 on moon snail, Polinices duplicatus (Say); in Laguna Madre, Texas, near Mansfield Channel marker 15, 26''33.5'N, 97‘’20'W, saUnity 42 ppt; 29.5°C: 13 August 1984; coU. S. R. Gittings. — TAMU, uncataloged: numerous, on oysters attached to dead gorgonian (Leptogorgia'l)\ north side of north jetty at Mansfield cut, Texas; salinity 35 ppt; 29.5®C; 13 August 1984; coll. T J. Bright. Remarks - Henry and McLauglilin (1975) documented B. venustus from Heald Bank, off Texas (approximately 29°04'N, 94°17'W), the only published record of the species west of Panama City, Florida, and north of Campeche Bay, Mexico. This species is represented in a collection returned by the R/V ALAMJNOS from 22 m at location 28°41'N, 94®48'W, according to Spivey (pers. comm.). Balanus venustus occurs in the eastern Atlantic, the tropical to north temperate western Atlantic, and the Indo- Pacific (Spivey 1981). It occurs in highest abundances on moDusc shells rather than on artificial surfaces. A notable exception was that reported by Pequegnat and Pequegnat (1968), who found it to occur in abundance on plastic fouling recruitment floats off Panama City, Florida, Aside from the report by Hedgpeth (in Wldtten et al. 1950) of B. amphitrite niveus seen (but not examined) on the Port Aransas (Texas) jetties (discussed earlier in the sections on B. trigonus and B. a. amphitrite), no unquestioned reports exist for B. venustus on artificial substrates in the north- western Gulf of Mexico. ACKNOWLEDGMENTS My thanks go to the curators of the regional museum collections for their kindness and assistance during my visits, Mr. Charles Dawson, Gulf Coast Research Labora- tory, Mr. Rick Kalke, University of Texas Marine Science Institute, and Dr, Allan H. Chaney, Texas A&I University. Thanks also to Dr. J. W. Tunnell for making his collection available to me. The generous efforts of Mr, George Dennis, who assisted me in sampling and in examining museum specimens, and those of Bonnie Bower-Dennis and Bryan L. Andryszak, who prepared tlie specimen figures, are appre- ciated. Thanks also to Dr. Henry Spivey, Dr. Mary K. Wicksten, Dr. R. Hays Cummins, Mr. George Dennis, and Mr. Jim Parrack for reviewing the manuscript. Tliis research was partially supported by funds from the Department of Energy Strategic Petroleum Reserve Program, contract number DE-AC96-80P010288 to Texas A&M University, and by a grant from the Texas A&M University Ocean- ography Departmental Development Fund. REFERENCES CITED AurivUUus, C. W. S. 1894, Studien uber Cirripeden. Svenska Vetenskaps-Academiens Handltngar 26(7): 1 —107. Broch, H. 1927. Studies on Moroccan driipeds (Atlantic coast). Bull. Soc. Sci. Nat. Maroc. au Rabat 7:11-38. Causey, D. 1961. The barnacle genus Octolasmis in the Gulf of Mexico. Turtox News :i9(2):S0 55. Darwin, C. 1851. A monograph of the subclass Cirripedia, with fig- ures of all species. The Lepadidae; or, pedunculated cirripedes. Ray Soc., London. Dawson, C. E, 1969. Records of the barnacle Conchoderma vir- gatum from two Gulf of Mexico fishes. Proc. La. Acad. Sci. 32:58-62. Foster, B. A. 1978. The Marine Fauna of New Zealand: Barnacles (Cirripedta: Thoracica). MZ. Oceanogr, Inst. Mem. 69. 160 pp. George, R. Y. & P. J. Thomas. 1979. Biofouling community dynamics in Louisiana shelf oil platforms in the Gulf of Mexico. RiceUniv. Stud. 65(4 and 5):553-574. Gittings, S. R. 1984. Seasonal cycles and monitoring of reCTUitment and growth of biofouling organisms in the vicinity of the West Hackberry Strategic Peiroleuin Reserve brine disposal site. Supplemental report of Post-disposal Studies to the U.S. Dept, of Energy Strategic Petroleum Reserve Program, Contract No. DE-AC96-80P010288. 37 pp. Gruvei, A. 1905. Monographic des Cirrhipedes ou Thecostraces. Barnacles of the Gulf of Mexico 41 Masson et Cie, Paris. 472 pp. Gunter, G. & R. A. Geyer, 1955. Studies on the fouling organisms of the northwest Gulf of Mexico. Publ. Inst. Mar. Sci. Univ. Tex. 4(l):37-67. Harding, J. P, 1962. Darwin’s type specimens of varieties otBalanus amphitrite. Bull Br. Mut. {Nat. Hist.) 9(7): 271 -296. Henry, D. P. 1954. Cirripedia; the barnacles of the Gulf of Mexico. Pages 443-446 in: P. S. Galtsoff (ed.), Gulf of Mexico, its Ori- gins, Waters, and Marine Life. U.S. Fish WUdl Serv, Fish. Bull 55(89). & P.A. McLaughlin. 1975. The barnacles of the Balanus amphitrite complex (Cirripedia, Thoracica). Zool Verb. 141. 254 pp. Hulings, N. C. 1961. The barnacle and decapod fauna from the near- shore area of Panama City, Florida. Q. J. Fla. Acad. Sci. 24(3): 215-222. Ichiye, T., H, Kuo & M. R. Carnes. 1973. Assessment of currents and hydrography of the eastern Gulf of Mexico. Department of Oceanography, Texas A&M University, College Station, Texas. Contribution No. 601. Jeffries. W. B.. H. K. Voris & C. M. Yang. 1984. Diversity and dis- tribution of the pedunculate barnacle Octolasmis Gray, 1825 epizoic on the scyllarid lobster, Thenus orientalis (Lund, 1793). Crustaceana 46(3): 300-308. Newman, W. .A. & A. Ross. 1976. Revision of the balanomorph barnacles; including a catalog of the species. San Diego Soc. Nat. Hist. Mem. 9. 1 08 pp. Nilsson-Cantell, C. A. 1938. Cirri pedes from the Indian Ocean in the collection of the Indian Museum, Calcutta. Mem. Indian Mus. 13(1);1-81. Overstreet, R. M. 1978. Marine Maladies? Worms, Germs, and other Symbionts from the Northern Gulf of Mexico. Mississippi- Alabama Sea Grant Consortium, MASGP-78-021 , 140 pp. Pearse, A. S. 1952. Parasitic crustaceans from Alligator Harbor, Florida. Q. J. Fla. Acad. Sci. 15(4):187-243. Pequegnat, W. E. & L. H. Pequegnat. 1968. Ecological aspects of marine fouling in the northeastern Gulf of Mexico. Texas A&M University Research Foundation Ref. 68-22T. 80 pp. Pilsbry, H. A. 1907. The barnacles (Cirripedia) contained in the collections of the U.S. National Museum. U.S. Natl. Mus. Bull 60:1-122. Rezak, R., T. J. Bright & D. W. McGrail. 1983. Reefs and banks of the northwestern Gulf of Mexico: their geological, biological and physical dynamics. Final Report to U.S. Dept, of Interior, Min- erals Management Service. Outer Continental Shelf Office, New Orleans, Louisiana. Texas A&M University, Department of Oceanography, Tech. Rep. No. 83-1-T, 501 pp. Ritz, D. A. & B. A. Foster. 1968. Comparison of the temperature responses of barnacles from Britain, South Africa and New Zealand, with special reference to temperature acclimation in Elminius modestus. J. Mar. Biol Assoc. U.K. 48:545-559. Ross, A. 1975. Heteralepas cornuta (Darwin) in the eastern Pacific abyssal fauna (Cirripedia Thoracica). Crusfflcctfnfl 28(l):17-20. . M. J. Ceraine-Vivas & L. R, McCIoskey. 1964. New barnacle records for the coast of North Carolina. Crustaceana 7:312-313. Southward, A. J. 1975, Intertidal and shallow water Cirripedia of the Caribbean. Stud. Fauna Curacao Other Caribb. Isl. No. 150. 53 pp. Spivey, H. R. 1981. Origins, distribution and zoogeographic affin- ities of the Cirripedia (Crustacea) of the Gulf of Mexico. 7. Bio- geogr. 8:153-176. Stebbing, T. R. R. 1895. Notes on Crustacea: two new pedunculate cirripedes. Ann, Mag. Nat. Hist. (6th Ser.) 15:18-22. Stephenson, T, A. & A, Stephenson. 1950. Life between the tide- marks in North America. 1. The Florida Keys, J. Ecol 38(2): 354-402. Thomas, P, J. 1975. The fouling community on selected oil plat- forms off Louisiana, with special emphasis on the Cirripedia fauna. M.S. Thesis, Depl. of Oceanography, Florida State Univ., Tallahassee. 129 pp. Weisbord, N. E. 1979. Lepadomorph and verrucomorph barnacles (Cirripedia) of Florida and adjacent waters, with an addendum on the Rhizocephala. Am. Paleontol 76(306): 1-1 56. Wells, H. W. 1966. Barnacles of the northeastern Gulf of Mexico. Q. J. Fla. Acad. Sci. 29(2):81-95. Whitten, H. L., H. F. Rosene & J. W. Hedgpeth, 1950. The inverte- brate fauna of Texas coast jetties; a preliminary survey. Publ. Inst. Mar. Set Univ. Tex. l(2):53-87. ZuUo, V. A. 1979. Marine flora and fauna of the northeastern United States. Arthropoda; Cirripedia. iVO/1 A Tech. Rep. NMFS Circ. 425. 29 pp. Gulf Research Reports Volume 8 | Issue 1 January 1985 Spatial Influences on Temporal Variations in Leaf Growth and Chemical Composition of Thalassia testudinum Banks Ex Konig in Tampa Bay^ Florida Michael J. Durako Florida Department of Natural Resources Mark D. Moffler Florida Department of Natural Resources DOI: 10.18785/grr.0801.07 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Durako, M. J. and M. D. Moffler. 1985. Spatial Influences on Temporal Variations in Leaf Growth and Chemical Composition of Thalassia testudinum Banks Ex Konig in Tampa Bay, Florida. Gulf Research Reports 8 (l): 43-49. Retrieved from http:// aquila.usm.edu/gcr/vol8/iss 1/7 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor ofThe Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research Reports, Vol. 8, No. 1 , 43-49, 1985 SPATIAL INFLUENCES ON TEMPORAL VARIATIONS IN LEAF GROWTH AND CHEMICAL COMPOSITION OF THALASSIA TESWDINVM BANKS EX KONIG IN TAMPA BAY, FLORIDA MICHAEL J. DURAKO AND MARK D. MOFFLER Florida Department of Natural Resources, Bureau of Marine Research, 100 Eighth Avenue S.E., St. Petersburg, Florida 33701 ABSTRACT The importance of spatial influences on seasonal fluctuations in Tfialassia testudinum leaf blade lengths and chemical constituents was demonstrated. Differences between samples from fringe and mid-bed for several constituents were significant and, if not accounted for, could affect the measurement of apparent seasonal cycles. Fringe-shoots, rellect- ing the influence of more intense grazing activity , had shorter leaf blade lengths, lower dry weights and carbohydrate levels, and higher protein levels than mid-bed shoots. Mid-bed rhizomes and roots had highest protein and ash levels reflecting possible sediment influence. Percent ash and protein in the rhizomes, and percent carbohydrate in the roots exhibited •iea.sonal fluctuations, but the levels were different between fringe and mid-bed samples. Protein levels were greatest in shoots and roots, while carbohydrate levels were highest in rhizomes, illustrating the respective partitioning of biosynthetic and storage functions. The spatial differences seem to reflect gradients in biological and chemical interactions, and they may play an important role in trophic interactions in seagrass INTRODUCTION Studies on chemical composition of several seagrass species have demonstrated the presence of annual cycles (Walsh and Grow 1972, Harrison and Mann 1975, Dawes et al. 1979, Dawes and Lawrence 1980). Walsli and Grow (1972) and Dawes and Lawrence (1980) showed that in the dominant Florida seagrass, Thalassia testudinum. protein levels generally were highest in spring and early summer, while carbohydrate, ash, and dry weight levels peaked in the fall. Rhizomes contained relatively large amounts of carbo- hydrates, and function as storage organs for nutrient reserves. In contrast, leaves and shoots usually had higher protein levels than rhizomes due to greater biosynthetic activity. Most previous studies of seasonality in seagrasses have utilized random sampling techniques which assumed that seagrass meadows were uniform communities. However, when environmental or successional gradients are suspected in a plant community, sampling along transects is more appropriate than random sampling (Whittaker 1967). In this regard, Zieman (1972) reported lower leaf blade den- sities and shorter blade lengths at the fringe compared to the center of circular beds of T. testudinum in Biscayne Bay, Florida. Capone and Taylor (1977), also working in Biscayne Bay, found that the dry weiglit of leaves per short- shoot and the number of leaves per square meter were lower at the fringe of a T. testudinum bed than in the interior. They also reported higher N 2 fixation activity associated with intact foliage at the fringe. Additional spatial trends have been observed in temperate Zostera marina L. meadows (Fonseca 1981, Kenworthy 1981). Kenworthy (1981) noted the largest pools of sedimentary Manuscript received March 18, 1 985; accepted May 31, 1985. systems. nitrogen, finest sediments, and liighest shoot production may be associated with the mid-bed regions of Z. marina meadows. He suggested that fringe areas represent colonizing stages of growth, while mid-bed regions illustrate later successional stages. Organic matter content of sediments and leaf area index (LAI) may also increase with distance into a bed (Fonseca 1981). This study examined the spatial and temporal variations of chemical constituents in T testudinum shoots, rliizomes, and roots. We utilized transect sampling to determine; (1) the allocation of chemical constituents within plant organs, (2) if spatial variations between the fringe and the interior of a seagrass bed differed significantly, and (3) if the spatial differences were large enough to obscure appar- ent seasonal patterns. MATERIALS AND METHODS Samples of T. testudinum were obtained monthly from a small circular seagrass bed (approx. 23 m dia) adjacent to Lassing Park (27°4S'N, 82''38'W) in Tampa Bay, Florida (see description of Beach Drive, SE, Phillips 1960), Samples were obtained using a posthole digger (approx. 15 cm dia by 20 cm deep). Eleven sample plugs were removed each month at alternate meters along transects which bisected the bed and extended from fringe to fringe. January’s transect was oriented along the east-west axi.s of the bed. Subsequent transects were rotated 30 degrees so the bed was ultimately bisected by six transects wliich were sampled twice over the r2-month study period. Samples one and eleven represented the fringe of the bed while samples four through eight were considered the mid-bed region. Water depth and the length of the longest intact leaf blade from four randomly chosen shoots (shnrt-shoots) were measured at each sample point. Water temperature and salinity were measured each month. 43 44 DURAKO AND MOFFLER Plugs were washed free of sediment and separated into shoot, rhizome, and root fractions within 2 h of coUection. Floral and faunal epiphytes were removed from the leaf blades by gently scraping under a stream of water. Each fraction was then blotted dry and weighed (fresh weight), dried at 60°C to constant mass, and reweighed to determine percent dry weight. The entire dried fractions were ground in a mill (screen size #40) and stored in a dessicator over CaCl 2 until the chemical analyses were performed. Percent ash was determined by weight loss after com- bustion of duplicate 50-mg subsamples in a muffle furnace at 500^C for 4 h. Protein was measured after extraction of 30-mg subsamples with 1 N NaOH by Folin reagent using bovine serum albumin as the standard (Lowry et al. 1951). Soluble carbohydrate was measured after extraction of 10-mg subsajnples with 5% hot trichloroacetic acid (TCA) by the phenol-sulfuric acid method (Dubois et al. 1956) using glycogen as the standard. Protein and carbohydrate analyses were done in triplicate. The levels of the constitu- ents were expressed as percentage of dry weight. Seasonal patterns were statistically analyzed using data pooled from all samples of a transect, whereas spatial distinctions were determined by pooled monthly data for each sample point. Normality of the data was assessed using Kolmogorov-Smirnov tests for normality (p<0.05). Multi- variate analyses of variance were performed to determine if chemical constituents exMbited significant (p<0.05) tem- poral or spatial variation. If significanl variation occurred, means were compared using Duncan’s multiple range tests (p<0.05). Calculations were performed using Statistical Analysis System (SAS) computer programs (Barr et al. 1976). The SAS/GCONTOUR procedure was used to gen- erate a contour map of the circular bed utilizing water depth data. RESULTS Seasonal variations Pronounced seasonal variations ofsalinity, water temper- ature, and leaf blade lengths were evident at Lassing Park. Although salinity fluctuated between 25 and 28 ppt for 75% of the year reaching higliest levels during the early sum- mer (Figure la), high rainfall amounts in late summer-early fall resulted in substantially reduced salinities. Water tem- perature (Figure lb) and mean longest leaf blade lengths (Figure 2) exhibited sin^ilar seasonal patterns; they increased from spring to summer and decreased from fall to winter. Maximum leaf blade lengths decreased slightly dur- ing the summer (Figure 2), coincident with highest water temperatures, floral anthesis, and initial fruit development. Water temperatures ranged from 11.5“C to 3I.5^C during the year, while leaf lengths varied from 13.4 cm to 23.3 cm. Seasonal variability was also evident in the chemical composition, of T, testudinum and the patterns were generally distinctive between plant organs (Table 1). J FMAMJ JASOND Month Figure 1 . Seasonal fluctuations in (a) salinity and (h) water tempera- ture at Lassing Park site. Month Figure 2. Seasonal fluctuations in maximum leaf blade lengths for Thalassia testudinum from Tampa Bay, Florida. Spatial and Temporal Variations in Thalassia 45 TABLE I Seasonal proximate analyses of Thalassia testudinum from Tampa Bay, Florida. Dry weight is expressed as a percentage of fresh weight. Ash, protein, and soluble carbohydrate levels are expressed as percentage of dry weight. Means of pooled transect samples ± one standard deviation are listed, n = 1 1. Component Months Jan Feb Mar Apr May Jun Jiy Aug Sep Oct Nov Dec Shoots Dry weight 11,88 10.63 10.46 10.55 9.64 10.44 10.28 10.49 10.28 10.49 9.97 9.99 ± 1.15 0.99 0.94 1.02 0.61 0.81 0.69 0.40 0.78 0.86 0.72 0.84 Ash 42.7 24.6 25.1 28.5 34.0 34,5 30.2 25.9 25.7 26.1 27.0 28.2 + 7.3 5.3 4.4 2.6 4.1 3.8 2.5 2.9 1.4 2.2 3.6 5.6 Protein 4.0 2.8 3.3 3.4 2.4 3.3 3.0 4.2 5.1 4.0 3.6 3.2 + 1.3 1.1 0.9 1.0 0.7 1.3 1-1 1-0 2.4 1.4 0.8 1.0 Carbohydrate 9.9 16.1 14.5 11.8 11.9 13.5 10.8 13.8 14.3 16.1 14.5 13.3 + 2.5 6.6 2.9 1.7 1.7 2,4 1.4 4.0 3.1 3.7 3.6 3.8 Rhizomes Dry weight 15.78 16.30 16.36 15.98 15.15 16.03 16.89 16.85 16.74 15.84 15.87 16.14 + 3.21 0.78 0.91 0.87 1.62 1.33 0.96 1.37 2.04 0.83 0.86 0.68 Ash 26.7 21.6 22.7 23.7 23.9 23.4 21,4 19.5 20.5 19.4 21.4 21.5 + 5.1 1.2 1.7 2.1 1.4 2.4 1.3 2.0 2.1 1.4 1.5 1.2 Protein 2.8 1.7 1.2 1.3 1.3 1.5 1.2 1.2 2.4 1.5 1.3 1.0 + 1.0 0.6 0.4 0.7 0.4 0.9 0.7 0.3 0.9 0.4 0.3 0.3 Carbohydrate 19.4 24.7 23.2 23.7 22.8 21.6 26.5 31.8 30.8 30.4 28.1 27.5 + 4.4 5.3 5.1 1.9 4.6 5.9 6.2 8.6 6.5 6.6 4.5 4.3 Roots Dry weight - 13.02 14.58 14.32 13.16 13.33 12.88 11.22 11.49 11.98 11.77 12.29 + 1.00 1.80 1.52 1.65 1.56 0.94 1.28 1,52 1.93 0.84 1.22 Ash - 31.9 31.4 36.1 33,6 32.5 30.5 26.5 26.6 25.7 26.4 25.8 + 3.7 6.3 7.5 3.8 3.7 3.3 1.8 1.7 3.8 1.9 5.9 Protein - 3.6 3.5 3.0 4.0 3.9 3.9 4.7 4.6 4.3 5.0 4.2 ± 0.8 0.9 1.3 1.4 0.8 1.4 1.0 1,5 1.0 1.2 1.4 Carbohydrate - 9.9 9.4 12.0 10.5 12.0 12.1 12.6 15.1 12.1 13.4 11.7 + 1.7 1.4 2.2 2.1 3.2 3.0 3.1 3.5 2.7 1.9 1.9 Dry weights of shoots were significantly greater in January than in any other month and lowest in May. The highest dry weights in rhizomes occurred in late summer— early fall and were also lowest in May. Root dry weiglits, higliest during the spring, decreased significantly during the sum- mer, reaching minimum values in the fall. Shoots had the lowest dry weights (9.5—11.8%) and rhizomes had the highest (15,1—16.9%); roots were intermediate (11.2- 14.6%), Ash levels exhibited seasonal patterns that were similar in all three organs. Low ash levels were present dur- ing early spring and fall, while highest levels occurred dur- ing late spring early summer with a peak in January. This pattern corresponded with fluctuations in salinity (compare Figure la and Table 1). Ash levels were higliest in shoots (24-42%) and lowest in rhizomes (19-27%); roots were again intermediate (25-36%). Carbohydrate levels in shoots exhibited a bimodal seasonal pattern with peaks in February and October (Table 1). The seasonzil pattern exliibited by both rliizomes and roots was slightly different; levels were lowest during spring then increased significantly during the late summer- early fall. Carbohydrate levels in shoots and roots ranged from 9 to 16.5%; levels in rhizomes were significantly higher (19-32%). Protein levels in shoots and rhizomes were lowest in spring and highest in January and September. Root levels were low in spring and increased through fall. Protein levels of shoots and roots (2-5%) were similar and always higher than those of rhizomes (1 —3%). Spatial variations The seagrass bed we sampled had a “domelike” profile and water depth decreased approximately 10 cm from fringe to mid-bed, a lateral distance of about 10 m (Figure 3). Except for fringe samples, leaf lengths also tended to decrease toward the interior of the bed (Figure 4). The relatively short leaf blade lengths of fringe short -shoots, although in deeper water, were attributed to grazing activity which is more prevalent along fringe areas of these seagrass beds (personal observation). Dry weight levels of shoots were significantly greater (10.5-10.9%) in the interior of the bed than on the fringe (Table 2). Roots exhibited the opposite trend and rhizomes showed no significant differences across the bed. Ash levels in shoots decreased significantly from the landward fringe (33,3%) to the seaward fringe (27.9%) (Table 2), while rhizomes had highest ash levels in the interior of the 46 Durako and Moffler bed (22.3—23.0%) and the lowest levels at the fringe (21.0 and 213%). Ash levels in roots fluctuated across the bed with little apparent pattern, but highest levels occurred in the mid -bed region. Carbohydrate and protein levels in shoots and roots were 1 ae Figure 3. Depth profile of the circular Thalassia testudinum bed at Lassing Park showing mounded bed form. 25 r 10 I ‘ ' ‘ ' ^ ' ' ' ' ' ’ I 2 3 45 67 89 10 II Sample Figure 4. Spatial variation in maximum leaf blade length of Thalassia testudinum along transects through the circular bed. inversely related along transects (Table 2). Carbohydrate levels of shoots were significantly lower at the fringe (10.9 and 12.6%) than in the interior (13.2-14.4%, except for sample #4). The opposite was true for protein levels. Root carbohydrate levels were significantly greater at the fringe while protein levels were significantly lower. Spatial varia- tions in rhizome carbohydrate and protein were distinctive. The seaward fringe rliizomes had significantly more carbo- hydrate than the rest of the bed; but the interior had signifi- cantly higlier protein levels. Analyses of variance indicated samples obtained at the fringe of this T. testitdinum bed had mean levels signifi- cantly different than those obtained from the interior for dry weight in shoots, percent, ash and protein in the rhizomes, and percent carbohydrate and protein in roots. No significant synergistic interactions occurred between the month of sampling and sample location. DISCUSSION Seasonal variations Seasonal patterns observed in this study, based on pooled transect data, agree closely with those previously reported for T. testudinum using random sampling tech- niques. Maximum leaf lengths of T. testudinum at Lassing Park exhibited a bimodal seasonal pattern with peaks in May and October. Phillips (1960) reported a similar pattern and suggested that leaf lengths in this species correspond with water temperatures. The transient summer depression of leaf lengths we observed coincided with highest water temperatures, rapidly falling salinities, and period of floral anthesis. Zieman (1975) also observed a decrease in leaf lengths during summer, but attributed it to the shunting of energy resources of the plants into the formation of sexual reproductive structures, .sexual reproduction apparently decreasing the energy available for vegetative growth. Yet he stated that sexual reproduction in T. testudinum was not extensive. Reproductive short-shoot density estimates range 1—15% for most south and central Florida T. testudinum populations (Phillips 1960, Thorhaug and Roessler 1977, Grey and Moffler 1978); therefore, only a small portion of the shoots would be involved in this reproduction related sag phenomenon. In contrast, reproductive shoot densities at lassing Park range 14-75% (Moffler et al. 1981), so a physiological shift could be substantial in this population. The entire community was exposed to the extremes of highest water temperatures and lowest salinities and our observations indicated that both vegetative and reproduc- tive shoots exhibited summer dieback. When water tem- peratures approach summer maxima in Tampa Bay, T. testudinum leaves become soft and flaccid then break off because of protoplasmic breakdown and accelerated bacterial activity (Phillips 1960). Salinity decreases also reduce leaf growth in this species (Phillips 1960, McMillan and Moseley 1967). Therefore, the combination of Spatial and Temporal Variations in Thalassia 47 TABLE 2 Pioximate analyses of transect samples of Tltalassla tesrudinum from Tampa Bay, Florida. Dry weight is expressed as a percentage of fresh weight. Ash, protein, and soluble carbohydrate levels are expressed as percentage of dry weight. Means of pooled monthly collections ±one standard deviation are listed, n = 1 2 for shoots and rhizomes, n = 1 1 for roots. Component Transect Sample 1 2 3 4 5 6 7 8 9 10 11 Shoots Dry weight 10.07 10.15 10.37 10.50 10.84 10.88 10.78 10.50 10.26 10.54 9.55 + 1.10 0.53 0.75 1.53 0.92 0.90 0.71 0.66 0.81 0.89 0.96 Ash 33.3 30.6 29.9 30.3 28.7 29.1 28.2 27.5 29.5 28.1 27.9 ± 10.8 6.1 5.6 7.9 5.8 6.6 6.9 6.5 4.8 4.0 3.6 Protein 3.8 2.5 3.5 3.7 3.6 3.6 3.2 3,9 3.4 3.3 4.2 ± 2.2 1.0 1.4 1.0 1.4 1.2 1.1 1.9 1.2 1.0 0.9 Carbohydrate 10.9 14.8 13.2 11.8 13.2 14.2 14.4 13.4 13.5 14.9 12.6 + 2.4 4.4 2.6 4.0 3.3 3.2 4.2 4,4 3.6 4.8 3.4 Rhizomes Dry weight 16.32 16.10 16.55 15.99 15.41 16.61 16.32 16.12 16.04 16.25 16.22 + 0.99 1.14 0.86 0.77 2.37 1.84 1,75 1.13 0.98 1.37 1.96 Ash 21.3 21.4 22.4 22.0 23.0 22.3 22.4 22.6 22.3 22.1 21.0 + 2.9 2.0 2.5 2.2 5.6 2.4 1.9 2.2 2.5 2.7 2.4 Protein 1.1 1.2 1.2 1.7 1.9 1.5 1.8 1.9 1.4 1.7 1.9 + 0.5 0.4 0.5 0.9 0.8 0.6 1.0 0.9 0.8 0.7 0.9 Carbohydrate 25.1 26.7 26.4 24.7 25.2 25.4 27.1 25.1 26.2 23.5 30.2 ± 4.6 6.1 5.1 6.4 9.2 4.6 6.4 5.6 6.1 4.9 10.3 Roots Dry weight 13.46 12.66 12.76 12.18 12.74 12.22 12.74 12.55 12.78 12.53 13.50 ± 2.18 1.57 2.15 0.97 2.16 1.88 1.25 0.92 2.41 1.16 1.90 Ash 31.1 30.2 28.3 30.7 32.0 29.9 28.9 28.5 29.7 29.2 28.4 ± 6.6 7.9 2.5 3.3 6.4 4.2 4.2 4,0 5.4 5.2 8.1 Protein 3.0 4.1 4.3 4.8 4.1 4.2 4.6 4.0 4.2 4.4 3.3 + 1.4 1.2 1.5 1.0 1.1 1.6 1.2 0.8 1.3 0,9 1.0 Carbohydrate 14.5 11.1 12.10 11.7 11.0 11.0 10.9 10.6 12.3 12.0 13.2 ± 2.3 1.9 2.6 2.7 3.4 2.1 3.4 2.5 2.8 2,5 2.6 environmental factors and an innate biological rhythm re- sults in a summer dieback which may be expected annually. Minimal leaf lengths during the winter are likewise due to a combination of environmental factors. Leaf kills occur when the shoots are desiccated during extremely low tides associated with the passage of cold fronts. In addition, the plants are relatively dormant due to low water temperatures at this time, so recovery is slow. Seasonal fluctuations in the chemical constituents of T. testudinum also reflected the influence of temperature and salinity on the growth characteristics of this species. Dry weight levels in shoots decreased as water temperatures and leaf lengths increased, during periods of maximal growth, then leveled off during the summer dieback, a period of limited growth. Dry weight levels in rhizomes increased from spring to summer, reflecting changes in resource allo- cation from shoot growth to nutrient storage in rhizomes (Dawes and Lawrence 1980). The dry weight patterns of the roots suggested a lag in seasonal growth relative to the shoots. Ash levels in all three organs exhibited very similar sea- sonal patterns that corresponded to that of salinity. Lowest ash levels in seagrasses previously have been attributed to the presence of new shoot growth, which lacks calcareous epiphytes (Harrison and Mann 1975, Dawes et al. 1979). This does not apply to the patterns we found because most epiphytes were removed from the leaf blades prior to analyses. The sunilarity of the seasonal patterns in above- and below-ground organs suggests the possible influence of an environmental factor. Salinity influences ash levels in other marine plants (Durako and Dawes 1980); it may also be responsible for the observed seasonal fluctuations in T. testudinum since the relatively high ash levels of seagrasses are due to the presence of sea salt m their aerenchyma (Dawes 1981). Seasonal variations in carbohydrate and protein levels between above- and below-ground organs again reflected the functional relationship of shoots, rhizomes, and roots. Rhizomes act as storage organs for nutrient reserves in T. testudinum (Walsh and Grow 1972, Dawes and Lawrence 1979). Increases in carbohydrate levels from spring to fall probably result from the translocation of photosynthate in the form of starch from .shoots to rhizomes (Dawes and Lawrence 1979). Carbohydrate levels were always highest 48 Durako and Moffler in rhizomes while protein levels, which were relatively low due to the inclusion of both living and dead tissue in our samples, were always liighest in shoots and roots. These patterns exemplify the partitioning of biosynthetic activity and storage among organs. They also illustrate the inter- mediate nature of the roots that had seasonal carbohydrate fluctuations similar to those of the rhizome, but protein and carbohydrate levels comparable to those of the shoots. Patriquin (1972) suggested nitrogen requirements for T. testudimm growth could be satisfied by uptake in the sediment root layer. Tliis was determined using yield-supply correlations of leaves, rhizomes, and interstitial waters. Fix- ation of molecular nitrogen in the rhizosphere seems to be responsible for the supply of nitrogen required for observed production rates (Patriquin and Knowles 1972, Capone et al. 1979). Our observations of relatively high protein levels in the roots may reflect the conversion of fixed nitro- gen into organic compounds. Spatial variations When transect data were analyzed with respect to sample position, it was evident that location had a decided effect on some of the parameters studied. We found a direct rela- tionship between maximum leaf lengths and water depths (except at the fringe which was heavily grazed) similar to that reported by Phillips (1960), but contrary to the inverse relationship for circular beds in Biscayne Bay reported by Zieman (1972). Sediment depths are evidently the factor controlling leaf blade lengths in Biscayne Bay, since the circular patches occur over depressions in the bedrock surrounded by a tliin veneer of sediments (Zieman 1972). Sediment trapping by these circular beds, evidenced by the decrease in water depth at the center of the beds, was very important for maximum development of the conununity. Patch beds can also form when small clumps of seagrasses grow laterally while accumulating sediments and organic matter (Kelly 1980). The circular bed at Lassing Park, which seems to conform more to the lateral growth model, had a domelike depth contour (see Figure 3) and expanded radially approximately 1 meter during the study period. Kelly (1980) found that leaf blade cropping by herbi- vores forms a “halo” effect around seagrass beds. The circu- lar bed at Lassing Park exhibited this feature, and samples obtained from the fringe had distinctive chemical patterns that reflected the influence of cropping. Highest protein and lowest carbohydrate levels were observed for fringe shoots. By cropping the leaf blades, herbivores may provide themselves with a higlier energy food source. Dawes and Lawrence (1979) also observed liigh protein and low carbo- hydrate levels in experimentally cropped short -shoots of T. testudinum which they attributed to new leaf production. Increasing the proportion of young leaf blade tissue by crop- ping may be effective in increasing the efficiency of energy transfer between T. testudinum and herbivores. Healthy T. testudinum releases about 1.3% of its gross production as dissolved organic carbon (DOC) (Brylinsky 1977). The release of DOC increases tremendously in senescent tissues. This soluble material may then be absorbed by plankton (Turner 1978) and sediment heterotrophs (Brylinsky 1977), increasing the trophic complexity of carbon transfer. A depletion of soluble carbohydrates in T, testudinum rhizomes in response to defoliation has been reported (Dawes and Lawrence 1979), but we noted an increase in carbohydrate levels of the roots and the seaward fringe rhizomes. Myriophyllum spicatum, a freshwater macro- phyte, also increases the percentage of soluble carbohydrate in the roots in response to cropping (Kimbel and Carpenter 1981). These variable results indicate differences in alloca- tion of proximate constituents (affecting relative propor- tions) rather than differences in biosynthesis. High protein levels in fringe shoots may also be due, in part, to higlier nitrogen availability in the phyllosphere of this region of the bed. Capone and Taylor (1977) found that nitrogen fixation activity of epiphytized leaves can be 20% higher at the fringe phyllosphere of a T. testudinum bed compared to the interior of the bed, while activity associated with intact foliage may be three times higher. This relatively high activity compensates for the less effec- tive trapping and recycling of nitrogen from detritus at the fringe (Capone and Taylor 1977). Rliizosphere nitrogen availability, the amount of organic matter and silt-clay in the sediments may increase with lateral distance into a seagrass bed (Fonseca 1981, Ken- worthy et al, 1982). Our data indicated the proximate com- position of below-ground organs may be affected by these changes in sedimentary characteristics, Atnmonium regen- eration is liigliest where organic matter in the sediments is high (lizumi et al, 1982), and uptake of ammonium by sea- grass roots is greatest in liighly organic substrata (Short 1983). Thus, the high protein levels of mid-bed rhizomes and roots in T, testudinum may be due to increased nitro- gen availability and assimilation, wliile elevated ash levels may indicate higher interstitial salinities or solute concentra- tions resulting from increases in organic and inorganic ions. CONCLUSIONS Spatially related parameters can influence seasonal fluc- tuations in chemical constituents of Thalassia testudinum. Although seasonality dominated changes in the levels for most chemical constituents, others, such as shoot dry weight and root protein levels, were significantly affected spatially but not temporally. In addition, some constituents that exhibited significant seasonal fluctuations had distinctive patterns between fringe and mid-bed samples. Therefore, the presence of gradients across seagrass beds needs to be considered in future investigations of these communities. ACKNOWLEDGMENTS We would like to thank Dr. K. A. Steidinger and Dr. C. J. Dawes for critically reading tliis manuscript. Spatial and Temporal Variations in Thalassia 49 REFERENCES CITED Barr, A. J,, J. H. Goodnight, J. P. Sail & J. T. Helwig. 1976. /I user’s guide to SAS, 76. SAS Institute, Inc., Raleigh, North Carolina. Brylinsky, M. 1977. Release of dissolved organic matter by some marine macrophytes. A/crr. Biol. 39; 442-451. Capone, D. G. & B. V. Taylor. 1977. Nitrogen fixation (acetylene reduction) in the phyllosphere of Thalassia testudinum. Mar. Biol. 40:19-28. Capone, D. G., P. A. Penhale, R. S. Oremland & B. F. Taylor, 1979. Relationship between productivity and N 2 (C 2 H 2 ) fixation in a Thalassia testudinum community. Limnol Oceanogr. 24:117- 125, Dawes, C. J. 19S\. Marine Botany. John Wiley and Sons, New York, New York. , K. Bird, M. Durako, R. Goddard, W. Hoffman & R. McIntosh. 1979. Chemical fluctuations due to seasonal and cropping effects on an algaLseagrass community. Aquat. Dot. 6; 79-86. Dawes, C. J. & J. M. Lawrence. 1979, Effects of blade removal on the proximate composition of the rhi/ome of the seagrass Thalassia testudinum Banks ex Konig. Aquat. Bot. 7:255-266. 1980. Seasonal changes in the proximate constituents of the scagrasses Thalassia testudinum, Hatodule vjrightii and Syringodium filiforme Aquat. Bot. 8:371-380, Dubois, .M. K., A. Giles. J. R. Hamilton, P. A, Rebers & R. Smith. 1956. Colorimetric method for determination of sugars and related substances. Chem. 28:350 356. Durako, M. 3. & C. J. Dawes. 1980. A comparative seasonal study of two populations of Hypnea musciformis from the east and west coasts of Florida, USA. 1. Growth and Chemistry. Mar. Biol. 59:151-156 Fonseca, M. S. 1981. The interaction of a seagrass, marina L., with current flow. M.S. Thesis, University t)f Virginia, Char- lottesville. Grey, W. F. & M, D. Moffler, 1978. Flowering of the seagrass Thalassia testudinum (Hydrocharitaceae) in the Tampa Bay, Florida Aquat. Bot. 5:251-259. Harrison, P. G. & K. H. Mann. 1975. Chemical changes during the seasonal cycle of growth and decay in eelgrass iZostera marina) on the Atlantic coast of Canada. J. Fish. Res. Board Can. 32: 615-621. lizurni, H., A. Hattori & C. P. McRoy. 1982. Ammonium regenera- tion and assimilation in eelgrass (Zostera marina) beds. Mar. Biol. 66:59-65. Kelly, M G. 1980. Remote sensing of seagrass beds. Pages 69-85 in: R. C. Phillips and C. P. McRoy (fids.). Handbook of Seagrass Biology: An Ecosystem Perspective. Garland, New York, New York. Kenworthy, W. J. 1981. The interrelationship between seagrasses, Zostera marina and Hatodule wrightii. and the physical and chemical properties of sediments in a mid-Atlantic coastal plain estuary near Beaufort, North Carolina (U.S.A.). M.S. Thesis, University of Virginia, Charlottesville. , J. C. Zieman & G. W. Thayer. 1 982. Evidence for the in- fluence of seagrass on the benthic nitrogen cycle on a coastal plain estuary near Beaufort, North Carolina. Oecologia 54:152-158. Kimbcl, J. C. & S. R. Carpenter. 1981, Effects of mechanical har- vesting on Myriophyllum spicatum L. regrowth and carbohy- drate allocation to roots and shoots. Aquat. Bot. 11 ;121 - 127. Lowry, G,, N. M. Rosenbrougli, A. L. Fan & R. J. Randall. 1951. Protein measurement with Folin phenol reagent. J. Biol. Chem. 193:265-275. McMillan, C. & F. N. Moseley. 1967. Salinity tolerances of five marine .spermatophytes of Redfish Bay, Texas. Ecology 48:503- 506. Mofller, M. D., M. J, Durako & W, F, Grey. 1981. Observations on the reproductive ecology of Thalassia testudinum (Hydrochari- taceae). A t/lzor. 10:183-187. Patriquin, D. G. 1972, The origin of nitrogen and phosphorus for growth of the marine angiosperm Thalassia testudinum. Mar. Biol. 15:35-46. Patriquin, D. & R. Knowles, 1972. Nitrogen fi.xation in the rhizo- sphere of marine angiosperms. Mar. Biol. 16:49-58. Phillips, R. C. I960. Observations on the ecology and distribution of the Florida seagrasses. Fla. Board Conserv. Mar. Ijib. Prof. Pap. Ser. 2:1-72. Short, F. S. 1983. The response of interstitial ammonium in eelgrass (Zostera marina L.) beds to environmental perturbations. J. Exp. Mar. Biol Ecol. 68.195-208. Thorhaug, A. & M. A. Roessler. 1977. Seagrass community dynamics in a .subtropical l&goon. Aquaculture 12:253-277. Turner, R. E. 1978. Community plankum respiration in a salt marsh estuary and the importance of macrophytic leachates. Limnol. Oceanogr. 23 : 44 2 -45 1 . Walsh, G. E. & T. E, Grow, 1972. Composition of Thalassia testu- dinum and Ruppia tnaritima. Q. J. Fla. Acad. Sci. 35:97-108. Whittaker. R. II, 1967. Gradient analysis of vcgelalum. Biol. Rev. 42:207 264. Zieman, J. C. 1972. Origin of circular beds of Thalassia (Spermato- phyta: Hydrocharitaceae) in south Biscay ne Bay, Florida, and their relationship to mangrove hammocks. Bull. Mar. Sci. 22:559- 574. . 1975. Seasonal variation of turtle grass, Thalassia testu- dinum Konig, with reference to temperature and salinity effect. Aquat. Bot. 1:107- 123. Gulf Research Reports Volume 8 | Issue 1 January 1985 Tanaidacea (Crustacea: Peracardia) of the Gulf of Mexico. IV OnNototanoides trifurcatus Gen. Nov.^ Sp. Nov.^ with a Key to the Genera of the Nototanaidae Jurgen Sieg Universitat Osnahruck Richard W Heard Gulf Coast Research Laboratory DOI: 10.18785/grr.0801.08 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Sieg; J. and R. W. Heard. 1985. Tanaidacea (Crustacea: Peracardia) of the Gulf of Mexico. IV. On Nototanoides trifurcatus Gen. Nov.; Sp. Nov.; with a Key to the Genera of the Nototanaidae. Gulf Research Reports 8 (l): 51-62. Retrieved from http://aquila.usm.edu/gcr/vol8/iss 1/8 This Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell(®usm.edu. Gulf Research Reports, Vol. 8, No. 1, 51-62, 1985 TANAIDACEA (CRUSTACEA: PERACARIDA) OF THE GULF OF MEXICO. IV. ON NOTOTAmiDES TRIFURCATVS GEN. NOV., SP. NOV., WITH A KEY TO THE GENERA OF THE NOTOTANAIDAE JURGEN STEG' AND RICHARD W. HEARD"' ^ Universitdr Osmbruck, Abt. Vechta, Driverstra^e 22, D-2848 Vechta, Federal Republic of Germany ^Parautology Sevlion, Gulf Coast Research Laboratory, Ocean Springs, Mississippi 39564 ABSTRACT Nototanoides trifurcatus gen. nov., sp. nov. is described and illustrated from the Gulf of Mexico. Nototan- oides differs from the other genera of the family by the male possessing a vestigial maxiUiped. It most closely resembles the genera Nototanais and Androtanais. In addition to the differences of the maxillipeds the males of Nototanoides can be separated by the A-segmemed antenna 1 and the females are distinguished by the trifurcate spine on the second segment of the palp of the maxiUiped. A key to known genera of the family Nototanaidae is presented. Sieg and Heard (1983) reported the tanaidacean Teleo- tanais gerlachi Lang, 1956, from the west coast of Florida, constituting the first record of the family Nototanaidae Sieg, 1976, from the Gulf of Mexico. Recently, specimens of a second member of this family, representing a new genus and species, have been made available to us by David K. Camp and Eric N. Powell. These specimens were collected on hard bottoms in both the eastern and western Gulf of Mexico. Nototanoides gen. nov. Diagnosis — With eyelobes; antenna 1 of female 3-seg- mented, in male 4-segmented. Female mandible with strong pars molaris; endite of maxilla 1 with 9 terminal spines, palp with 2 setae distally; maxiUiped without coxa, basis fused medially, endite also fused medially. Males with man- dibles, maxilla 1, maxilla 2, and labium greatly reduced, unrecognizable;^ maxiUiped vestigial with basis and endite fused medially; epignath present. Female marsupium formed by 4 pairs of oostegites. Sexual dimorphism of cheliped not well marked, but distinctly larger in male. Pereopods 4—6 with dactylus and terminal spine coalesced to claw. Five pairs of pIeopods,endopodwith distal setae on inner margin. Uropods biramous, endopodite 2'Segmented. Type-species: Nototanoides trifurcatus sp. nov. Gender: Masculine. Etymology — The ending -oides indicates that this genus is related io Nototanais Richardson, 1906. Remarks — Nototanoides is placed in the family Noto- tanaidae because the basis of the maxiUiped is fused medially, the dactyl and terminal spine of pereopods 4-6 are coalesced to form a claw, the uropodal endopod is only 2-segmented and the eyelobes are well developed. It is ex- cluded from the Leptocheliidae Lang, 1973, because the Manuscript received May 6, 1985; accepted September 24, 1985. members of that family are characterized by having an un- fused maxiUiped and the endopod of the uropod consisting of 3 or more articles (see Sieg \98A2i), Nototanoides cannot be included in the Paratanaidae Lang, 1949, because the members of this family have the basis as well as the endite of the maxUliped typically enlarged and the male differs totally in body shape from the female. The general body structure, armament of pereopods, and general shape of antenna 1 indicate that Nototanoides is most closely related to the nototanaid genera Androtanais Sieg, 1973, and Nototanais. Androtanais, known only from the male, is characterized by having (1) antenna 1 with 5 articles, (2) only remnants of the maxilla present, and (3) a nearly normally developed maxiUiped (only the endite reduced) with medially fused basis. The male “cheliped” of Androtanais indicates sexual dimorphism, unless the female is atypical for the family. This opinion is supported by the fact that the male “cheliped” of Androtanais is subchelate while in tiie known females of the other nototanaid genera it is chelate. In Nototanais the male also has an antenna 1 of 5 articles, but the third article is much shorter than in Androtanais. Nototanais is also characterized by having a relatively normal maxiUiped with the endite unfused. Sexual dimorphism of the cheliped is quite apparent. In males development of the propodus, fixed finger, and sometimes the carpus is much more pronounced and enlarged than in females. Nototanoides differs from Androtanais and Nototanais by the male having an antenna 1 with 4 articles (third article very small), less sexual dimorphism of the cheUpeds (the male cheliped is much larger and stronger than that of the female but otherwise similar), and a strongly reduced male maxiUiped (basis small and fused medially, palp lacking, endite fused). In the female of Nototanoides, the endite of maxilla 1 has only 9 terminal spines instead of 10 as in Nototanais. As \n Androtanais, the endite of the maxiUiped is almost totally fused in Nototanoides. By contrast, males of Nototanoides and Nototanais have greatly reduced mouthparts with only the reduced palp of maxilla 1 remaining. 51 52 SiEG AND Heard KEY TO THE GENERA OF THE FAMILY NOTOTANAIDAE 1. Antenna 1 with more than 4 articles (mouthparts reduced except maxilliped) 2 Antenna 1 with at most 4 articles 4 2. Antenna 1 with 8 articles (peduncle with 3 and flagellum with 5 articles), body extremely attenuated Tanaissus Norman and Scott (males) Antenna 1 with 5 articles, body not extremely attenuated 3 3. Last 3 joints of antenna with groups of aesthetascs, third joint annular Nototanais Richardson (males) Only the last joint bearing one aesthetasc distally, third joint elongate Androtamis Sieg (males)* 4. Antenna 1 with 4 articles 5 Antenna 1 with 3 articles . 6 5. Second and third segments of antenna subequal, third segment lacking aesthetascs, mouthparts present Teleotanais Lang (females)** Tliird segment of antenna 1 annular, distinctly shorter than second segment, with a group of aesthetascs; mouthparts including the maxilliped reduced Nototanoides gen. nov. (males) 6. Pleopods well developed 7 Pleopods reduced Metatanais Shiino (females)** 7. Eyelobes present 8 Eyelobes absent 9 8. Maxilliped with endite unfused medially, a short seta near articulation of palp, segment 2 of palp with ciliate spine; maxilla 1 with endite bearing 10 terminal spines JVototanais (females) Maxilliped with endite fused proximally, only distal third unfused, 1 long seta near articulation of palp, segment 2 of palp with strong trifurcate spine; maxilla 1 with endite bearing 9 terminal spines Nototanoides gen. nov. (females) 9. Endite of maxilliped fused medially Tanaissus (females) Endite of maxilliped un fused medially Pro tanaissus Sieg (females)** *Female unknown **Male unknown Nototanoides trifurcatus sp. nov. Holotype — Female, National Museum of Natural His- tory, USNM 222507; off Texas coast, East Flower Garden Bank, 72 m, Gollums Lake, Sta. 80-24, 27‘’S4'36.64"N, 93°34'53.27"W. Allotype — Male, National Museum of Natural History, USNM 222508; same locality as holotype. Para types - 1 9 + 2 dd in collection of Sieg and 16 99, 5 dd, 1 manca-IIl, USNM 222509; same locality as holo- type; 8 99 + 2 neuters, USNM 216175; East Flower Garden Bank, 120 m, 22 June 1975; 6 99 + 3 dd, East Flower Gar- den Bank, Gollums Lake, Sta, 80-19, USNM 216176; 1 neu- ter, 1 9, 2 dd, same locality, Sta. 80-R9, USNM 216177; 1 9, East Flower Garden Bank, Dive 6, USNM 216178. Additional material — Texas Hard Bank Study; 1 9, Geyor Bank, 27°49'24"N, 93®03'42"W, 190 m, USNM 216179; 2 dd, off Texas coast, Sackett Bank, 100 m, 28°38'or'N, 89°33'22’'W, USNM 216180; Project Hour Glass (Florida West Coast); 19, Sta. L, 26''24'00"N, 83°22'00"W, 54,9 m, USNM 216182; Sta. D, 27°37'00’'N, 83°28'00"W, 36.6 m, 1 9, USNM 216182; Sta, E, 27°37'00"N, 84°13'00"w. 73.2 m, 2 99, USNM 216182; Sta. C, 27°37'00’'N, 83°28'00’'W, 36.6 m, 1 9 + 1 <3, FSBC- 1-31419, 2 99 -t 1 <3. FSBC-1.31418; BLM Mississippi- Alabama-Florida Study; Sta. 2207, 27“ 57' 00.4" N, 83"09'00.3''W, 19 m, 1 juv.; Sta. 2423, 29°37'00.8"N, 84'’17'00.2'’W, 19 m, 1 9; Sta. 2852, 28°30’00.4"N, 83°29'S8.4''W, 22 m, 1 juv. -H 9, all USNM 216183. Description of female (paratype) (Figs. 1-7). Body — Length of adult females from 3. 0-3 .5 mm; sub- adults and inanca stages smaller; somewhat less than 5.5 times longer than broad (Fig. 1). 5 60 SiEG AND Heard Cephalothorax — Elongate, nearly 1.3 times longer than broad, gently rounded posteriorly and narrowed anteriorly, eyelobes relatively large, single small seta on lateral margin immediately posterior to each eyelobe, rostrum indistinct. Pereonires - All pereonites with one seta at anterior corner, lateral borders rounded with no spines or processes; first pereonite about 3.6 times broader than long, anterior and posterior border smooth, concave; second slightly more than 2 times as broad as long;third approximately 1 .9 times as broad as long, greatest width in anterior half; fourth 1 .5 times as broad as long; fifth 1.7 times broader than long; sixth 1,8 times broader than long, greatest width in pos- terior third. Pleonites — 5 tergites visible dorsally, all of same size, each nearly 4 times broader than long, each segment armed laterally with 2—5 small setae. Antenna 1 (Fig. 2) - 3-segmented; segment 1 longer than remaining 2 combined, nearly 4 times longer than broad, slightly curved stcrnally (ventrally), midsternaUy with 1 plumose seta, and distally with 3 strong plumose setae and 1 long naked seta, tergal border with 1 seta in the middle and distally; second segment smaller, about 2 times longer than broad, sternal margin distally with 4 aesthetascs, tergal margin with 2 naked setae and 1 plumose seta distally; third segment relatively small, but 2.3 times as long as broad, distally with 1 aesthetasc, 3 long and 3 short naked setae, and 1 plumose seta. Antenna 2 (Fig. 1) — 6-segmented; first segment small, as long as broad, partly fused with cephalothorax; second relatively large, laterally depressed with tergal border flat- tened, nearly 1 .5 times as long as broad, tergal margin with 1 seta, and some groups of minute setae distally; third, as long as broad, with 1 seta distally at tergal margin; fourth segment elongate and curved medially, 4 times as long as broad, with 1 plumose seta medially, and 5 naked setae as well as 1 plumose seta distally; fifth small, as long as broad, with 2 long setae distally; sixth minute, conical, with 1 short and 3 longer setae. Labrum (Fig. 3) — Hood-shaped, covered with very fine setae. Mandibles (Fig. 3) Robust, pars molaris well-devel- oped, having crushing area surrounded with strong raised margin, % of margin notched; left mandible with strong crenulate Jacinia mo bills and well-developed pars indsiva; right mandible without kcitiia mobilis (fused with tlie pars incisival), with strong bifid crenulate pars incisiva. Labium (Fig. 3) — With inner and reduced outer lobe; inner lobe deeply incised in middle, distal part covered with groups of very small setae. Maxilla I (Fig. 3) — With endite and uniarticulate palp; endite with 9 normal spines; palp nearly as long as endite, with 2 relatively short setae. Maxilla 2 (Fig. 3) - Of normal size for family, oval, lack- ing setae. Maxilliped (Fig. 3) - Without coxae, well-developed; basis fused medially, with 1 long seta near articulation of palp; endite of normal size, distal third unfuscd medially, each side with 2 di.sta] setae, 2 membranous hemispherical structures, and very small setae on distolateral margin. Palp with 4 articles; first article sligjitly longer than broad, with- out setae; second triangular, outer margin with 1 seta, inner margin with 2 setae and 1 strong, 3-pointed (“trifurcate”) spine; third segment 1.25 times longer than broad, inner border with 3 serrate setae and 1 naked seta; fourth small, with 1 short seta on outer border, and 5 serrate setae on inner border. Epignath (Fig. 3) - Falciform, with minute hairs at tip. Cheliped (Fig. 4) - Strongly developed; sidepiece large, behind proximal conjunction of basis;latter 1 .8 times longer than broad, no seta; merus triangular, elongate, and reach- ing nearly to middle of carpus, 1 rostro-sternal seta; carpus 1.7 times longer than broad, tergal border with 1 distal and 1 proximal seta, sternal border with 1 rostral and 1 caudal posterior seta; propodus of normal size, fixed finger with strong spine at tip, tergal border with 3 rostral setae, sternal border with 6 rostral setae, caudaUy with 1 seta near articu- lation of dactylus, comb consisting of 13 (variable) short, serrated setae and 1 Jong serrate seta; dactylus curved, tip strongly calcified and colored more or less dark brown, 1 rostral seta. Pereopod 1 (Fig. 5) — Slender, coxa small, not fused with pereonite, without setae; basis slender, 3. 7 times longer than broad, tergal border with 1 rostral naked seta and 1 plumose seta; ischium small, with 1 tergal seta; merus elongate, 1.25 times longer than broad, sternal border with 1 rostral seta distally; carpus 1.7 times longer than broad, distally with 1 rostral and 1 caudal seta sternally as well as tergally; dactylus with spine, nearly as long as propodus, with 1 small seta proximally. Pereopod 2 (Fig. 5) - Coxa small, not fused with pere- onite, without setae; basis nearly 3 times as long as broad, sternal border with 3 short setae proximally; ischium small, with 1 tergal seta; merus 1 .2 times longer than broad, tergal border distally witli 1 rostral and caudal seta; carpus 1.7 times longer than broad, distally with 1 rostral and caudal spine tergally as well as sternally, sternal third with groups of tiny setae; propodus 3.3 times longer than broad, tergal border with 1 spine distally; dactylus curved, reaching approximately 2/3 length of propodus. Pereopod 3 (Fig. 5) — Proportion and armament as in P.2, but carpal spines sliglitly larger. Pereopod 4 (Fig. 6) — Coxa fused with pereonite; basis 3 limes longer than broad, sternal border with 2 plumose setae proximally and tergal border with 2 plumose setae distally; ischium small, with 2 tergal setae; merus nearly 2 times longer than broad, distally with 1 rostral and 1 ter- gal spine sternally and tergally, 1 distal seta at sternal bor- der; propodus 3 times longer than broad, distally tergal margin with 1 rostral and 1 tergal spine, sternal margin with feathered hair in middle and 1 long distal seta, distal third New Tanaidacean Genus from the Gulf of Mexico 61 With groups of minute setae; dactylus and spine fused as claw, half as long as propodus. Pereopod 5 (Fig. 6) - Proportions and armament as in P.4; except merus, bearing distally 1 rostral and 1 caudal seta on sternal border, and propodus bearing 2 plumose setae. Pereopod 6 (Fig, 6) - Proportions and armament as in P.4 and P.5 , except for propodus bearing 1 large spine and 3 additional short spines at sternal border distally. Pleopods (Fig. 7) - All 5 pairs of pleopods similarly de- veloped; basis nearly as long as broad, without setae; exo- pod uniarticulate, without setae on inner border, with many setae on outer border, most proximal 1 stouter than others, separated by gap from them; endopod uniarticulate, with 1 seta at distal inner border, many setae on outer border. Pleotelson (Fig. 7) — Normally developed, slightly more than twice as broad as long, caudal lobe prominent, with 2 small and 2 longer setae, with 2 setae medial to, and 1 seta lateral to, articulation of uropod; 2 additional setae near border witli fifth pleonite, Uropods (Fig. 7) - Short, biramous. Protopod (basis) developed normally, 1 .25 times longer than broad, with 1 small seta near articulation of exopodite. Endopodite short, 2-segmented; first segment with 1 long seta distally; second segment with 2 long setae at tip. Exopodite 2-segmented; first segment about twice as long as broad, with oblique row of 5 plumose setae, and 1 long distolateral seta; second segment nearly 3 times as long as broad, with 1 short naked seta, 2 plumose setae, and 4 long setae at tip. Description of male Type I (paratype) {Figs. 1-7). Body — Length of “adult” males (= copulatory 6 Type B? of Sieg 1984) 3. 2- 3. 7 mm; approximately 6 times longer than broad, shape different than that of the female (Fig. 1). Cephalothorax — Elongate, approximately 2/5 total length of animal, anterior half laterally compressed, borders parallel, eyelobes large, with small seta adjacent to it, pos- terior lialf strongly inflated, bearing carapace fold, 1 small seta present. Pereonites — All 6 pereonites with 1 seta on anterior corner, borders much more rounded than in female; first pereonite small, nearly 4.5 times longer than broad, anterior and posterior border smoothly concave; second and third pereonites about 2.6 times and 1 .8 times broader than long, respectively, with lateral borders strongly convex; fourth and fifth pereonites 1.7 and 1.6 times broader than long, respectively, with anterior and posterior part laced, lateral borders convex; sixth twice as broad as long, only anterior part laced. Pleonites — Similiar to female, but only 3 times broader than long. Antenna J (Fig. 2) - 4-segmeiited, elongate, much stronger than female; first article longer than remaining ones, 4.5 times longer than broad, sternal margin with 3 plumose setae at proximal 1/3, with 4 plumose setae and 1 long seta in middle and with 3 plumose setae and 1 long seta distally, tergal border with 1 seta in middle and 1 seta and 1 feathered hair distally; second segment 1.8 times longer, distally with 2 small setae tergally and I longer seta sternally; third segment small, annular, with 1 aesthetasc; fourth segment 2.3 times longer than broad at the basis with scale bearing 4 aesthetascs, with 1 additional aesthe- tasc, 4 longer and 2 shorter setae distally. Antenna 2 (Fig. 1) - Similar to female, except for some minor differences distally (plumose setae instead of naked setae at distal end of antepenultimate segmem). Mouthparts - Greatly reduced, vestigial. Maxilliped (Fig. 3) - Strongly reduced; basis small, fused medially, with 1 long seta distally on each side (near original articulation of palp); palp missing; endite totally fused, with 2 long setae distally. Epignath (Fig. 3) - As in the female, but larger. Cheliped (Fig. 4) - Much larger than in female^ with carpus much more voluminous; propodus with reduced spine at tip of fixed finger, comb more developed, consist- ing of about 22 short and 1 long setae; dactyl with rounded tooth. Pereopods 1-6 (Figs. 5-6) - Proportions and armament, except for basis, as in female; basis of all pereopods stronger than in female, tliickness of basis increasing from P.1-P.6, especially in P.4-P,6, rostral and caudal part of sternal margin prominent, U-shaped in cross section form- ing groove for carpus and propodus when leg is retracted. Pleopods, uropods (Fig. 7) — As in female. Pleotelson (Fig. 7) - Shorter than in female, 2.5 times broader than long; armament as in female. Description of male Type 2 (paratype) (Figs. 1 -2, 4). Body (Fig. 1) — Distinctly smaller, length approximately 2 mm; cephalothorax more elongate as in female, but less than in “adult” male (male 1 stage), anterior half laterally compressed; shape of pereonites similar to female. Appendages — Antenna 1 (Fig. 2) similiar to “adult” male Type 1, but proportionally smaller; mouthparts re- duced, maxilliped also reduced; cheliped small (Fig. 4), more like that of female; pereopods, pleopods, and uropods similar to the “adult” male. Remarks — The morphological comparisons have already been made in the discussion of the relationship of Nototan- oides to other nototanaid genera. Based on the work of Sieg (1984a), it appears that the male Type 1 and male Type 2 of Nototanides correspond to the “primary male” and “sec- ondar>' male” (type B and C), respectively. Nototanoides trifurcatus, like species of Notntanais, appears to follow the type of protogynous development (Sieg 1984b) repre- sented by Heterotanais oerstedti (Kr0yer, 1842). Like the males of Nototanats, those of Nototanoides have chelipeds that differ morphologically only slightly from those of the females. Additional male forms can be recognized only by their measurements. 62 SiEG AND Heard Ecological Notes — The specimens oiNototanoides trifur- caius examined during this study came from carbonate sands and rocks in depths tanging from 19 to 190 m. Off the Texas coast (East Flower Garden Bank), large populations of this and at least 10 other tanaidacean species were associ- ated with a natural anoxic, sulfurous brine seep. For detailed discussion of this unique habitat, see Powell et al. (1982). AC KN OWL E DGMENTS We wish to express our appreciation to David K. Camp of the Florida Department of Natural Resources and Eric N. Powell of the Department of Oceanography, Texas A&M University, for making specimens available to us for study. The manuscript benefited from the comments and constructive criticisms of two anonymous reviewers. Allen Child of the Division of Crustacea, National Museum of Natural History, kindly traced the location of USNM materials. We thank Cindy Dickens for typing the manuscript. REFERENCES CITED Powell, E. N, T. J. Bright, A. Woods, S. Gittings, & J. Johansen. 1982. The East Flower Garden brine seep: implications for benthic community structure. Technical Report No, 81-6-T, Te.xas A&M University, College Station. Sieg, J. 1983. Tanaidacea. Jn: Gruner, H. E. & L. B. Holthuis (eds ). Cat. Crustaceorum, Pari 6:1-552, 1984a. Neuere Erkenninisse zum Natiirlichen System der Tanaidacea. Zoologica (Stuttg.) 1 36: 1-132. 1984b. Tanaidacea of the United States Navy’s 1947- 1948 Antarctic Expedition (Crustacea). J. Crustacean Biol. 4(2): 298-306. Sieg, J. & R. W, Heard. 1983. Tanaidacea (Crustacea; Peracarida) of the Gulf of Mexico, III. On the occurrence of Teleotanais gerlachi Lang, 1956 (Nototanaidae) in the eastern Gulf. Gulf Res. Repi. 7(3) :267-271. Gulf Research Reports Volume 8 | Issue 1 January 1985 Yield-Per-Recruit of Spotted Seatrout Richard E. Condrey Louisiana State University Gerald Adkins Louisiana Department of Wildlife and Fisheries Michael W Wascom Louisiana State University DOI: 10.18785/grr.0801.09 Follow this and additional works at; http://aquila.usm.edu/gcr Part of the Marine Biology Commons Recommended Citation Condrey, R. E., G. Adkins and M. W. Wascom. 1985. Yield-Per-Recruit of Spotted Seatrout. Gulf Research Reports 8 (l): 63-67. Retrieved from http;//aquila.usm.edu/gcr/vol8/issl/9 This Short Communication is brought to you for free and open access by The Aquda Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research Reports, Vol. 8, No. 1, 63-67, 1985 SHORT COMMUNICATIONS YIELD-PER-RECRUIT OF SPOTTED SEATROUT* RICHARD E. CONDREY’ , GERALD ADKINS^ AND MICHAEL W. WASCOM’ ^ Coastal Fisheries Institute, Center for Wetland Resources, Louisiana State University, Baton Rouge, Louisiana 70803-7503 ^Louisiana Department of Wildlife and Fisheries, Bourg, Louisiana 70343 ABSTRACT A von Bertalanffy growth curve, L = 65.47 cm (1 - e “ is derived from published data on spotted seatrout in the U.S. Gulf of Mexico and used in constructing a yield-per-recruit contour. Maximum yield-per-recruit is approached as F increases above I and age of first entry approaches 3.9 years (14.9 in., 1 .1 lb). A linear regression is derived relating average size of capture to gill net mesh size (MS in inches), L= 1.97 in. + 8.63 MS, and used along with legal sizes of first harvest to evaluate the impact of current laws in the Gulf states on yield-per-recruit of spotted seatrout. INTRODUCTION Spotted seatrout are one of the most important edible fmfish in the northern Gulf of Mexico. Despite their pre- eminence, there is a perception that scientific “information [on seatrout] is general and, for the most part, inadequate” to meet management’s needs (Lorio and Ferret 1980). Cur- rent regulation.^ on the size at harvest are not based upon a quantitative consideration of yield-per-recruit and spawner- recruit relationships. Rather, current laws are largely based upon expedient compromises between conflicting user groups (Ferret et al. 1980; Merriner 1980), In this note we present a yield-per-recruit analysis based entirely upon a synthesis of published data. While lacking the rigor of a study based upon its own data collection, this synthesis does offer a needed first look at the effect of cur- rent regulatory restrictions on the yield of this increasingly important resource. RESULTS AND DISCUSSION Construction of the yield-per-recruit contour A von Bertalanffy growth curve, L = 65.47 cm (1 _e “ ”>), ^This is contribution No. CFI-84-5, Coastal Fisheries Institute, Center for Wetland Resources, Loui^na State University, Baton Rouge, Louisiana 70803-7503, It results from research supported by the Louisiana Fisheries Initiative. Manuscript received October 23, 1984; accepted May 18, 1985. was fitted to size-at-age data (total length in cm) reported for seatrout in U.S. Gulf of Mexico estuaries (Fearson 1929, Klima and Tabb 1959, Moffett 1961, Stewart 1961, Tatum 1980, and Colura et al. 1984) (Figure 1). Mean annual air Figure 1 . Growth rate of spotted seatrout in the northern Gulf of Mexico. Tatum’s “Age 1+ . . . Age VI+” data are plotted as age 2 thiou^ age 7 fish under the assumption that all of the annual growth had occurred when the length-age measurements were made. 63 (in.) 64 CONDREY ET AL. temperature (1941-1970*, NOAA 1981, 1983a, b) of the coastal weather station nearest to each study site was used as an index of mean annual water temperature (Table 1). The average of these means was used as an estimate of the overall mean water temperature for the entire data set, Use of the combined growth equation and overall mean temperature in Pauly’s (1979) equation generated an instan- taneous rate of natural mortality (M) of 0.45 on an annual basis. These rales of growth and mortality predict that maxi- mum biomass of an unfished cohort is attained at 3.9 yr (14.9 in., 1.1 lb). Tatum (1980) reports a total annual mortality of 50% (Z = '0.69, where Z is the instantaneous annual rate of total mortality) for spotted .seat rout in Alabama. An instan- taneous rate of annual fishing mortahty (F) of 0.24 is estimated as the difference between Tatum’s Z and our M (F = Z - M = 0.69 - 0.45 = 0.24). For comparison, we reran the natural mortality analysis using the individual estimates of growth and temperature. The predicted individual estimates of M ranged from 0.22 to 0.65 with a mode of 0.36 (Table 1). Maximum biomass of an unfished cohort was predicted to occur over a range of 3.4 yr (14.2 in., 1.0 lb) to 8.4 yr (24.4 in., 5.0 lb) with modes of 4.9 yr and 15.9 in. (1.3 lb) (Table 1). We are not able to correlate the variation between these individual estimates with location or timing of the studies. For example, estimates were comparable for central and south central Texas despite the wide temporal range of these reporta, 1929 and 1984. In contrast, Moffett’s study generated two widely differing sets of estimates for north central and south central Florida. We assume that the real variation in growth rates which should occur as one moves from the southern to the northern estuaries of the U.S. Gulf of Mexico is not represented by the variation observed in these estimates. We use our combined equation as the best estimate of grow'lh througliout the rest of this paper. Data on the average sizes of fishes (total length in inches) caught in differing size mesh (MS in inches) of monofila- ment and multifilamenl gill nets arc plotted in Figure 2 (Trent and Pristas 1977, Matlock et al. 1978, Adkins et al. 1979, Lorio et al. 1980, Adkins and Bourgeois 1982, Amoldi 1982). Analysis of covariance indicates no signifi- cant effect of mesh type (mono- or multifilament) on the relationships between sizes of fish and mesh, L=1.97 in. + 8.63 MS (r^ = 0.90, H.S.). The minimum legal mesh sizes of giU nets in the various Gulf states (Table 2) were used in this wei^ted regression to estimate average size at entry. (cm) Figure 2. Relationship between mesh size of monofilament or multi- fOament gill nets and average length of spotted seatrout captured. Data from Matlock et al. 1978 (M); Trent and Pristas 1977 (T); Adkins et al. 1979 (A); Lorio et al. 1980 (L); Adkins and Bourgeois 1982 (G, monofilament; g, multifilament); and Arnold! 1982 (D). TABLE 1 Estimates of growth, mortality, and of age and size of maximum biomass predicted for an unfished cohort. Area of study Author Loo cm k annual to years Temp. °C M annual Age years Length in. Wt. lb Corpus Crisli, Texas Pearson 1929 71.4 .148 -0.640 22.2 .36 4.9 15,6 1.3 Matagorda, Texas Colura et al. 1984 72.6 .152 -1.288 21.4 .36 4.0 15.9 1.3 Coastal Alabama Tatum 1980 57.2 .362 0.616 19.8 .65 3.4 14.2 1.0 Apalachicola, Florida Klima and Tabb 1959 78.4 .140 -0.456 20.3 .32 5.6 17.5 1.8 Cedar Key, Florida Moffett 1961 114.4 .085 -0.814 22.0 .22 8.4 24.4 5.0 Fort Meyers, Florida Moffett 1961 62.6 .214 -0.343 23.3 .49 3.6 14.1 0.9 Flamingo, Florida Stewart 1961 85.2 .138 -0.579 25.0 .35 5.2 18.4 2.1 Combined AU of the above 65.5 .200 -0.411 22.0 .45 3.9 14.9 1.1 Short Communications 65 TABLE 2 Current size and gill net restrictions on the harvest of spotted seatrout in the northern Gulf of Mexico. Florida Alabama Mississippi Louisiana Texas Size limit Recreational 12 in. (but no size limit in Gulf and Franklin counties). 12 in. None None 14 in. Commercial 12 in. (but no size limit in Currently prohibited. 12 in. 12 in. Currently prohibited. Gulf and Franklin counties). Formerly 12 in. Formerly 12 in. Gill net Varies by local statutes Currently prohibited. 1.5 in. 1.75 in. Currently prohibited. mesh size or general statutes Formerly 1 .25 in. in Formerly 1,5 in. (minimum) of local application Mobile County and or by rules of the 1 .5 in. in Baldwin Marine Fisheries Commission that are approved by the Governor and Cabinet. County. Minimum Legal Age Minimum Gill at Legal Net First Sizes Mesh CinJ (in.) (yr) FISHING MORTALITY (F) Figure 3. A yield-per^ecruit contour for spotted seatrout in the northern Gulf of Mexico. Points indicate the entry levels associated with the current or recent Gulf state laws on minimum legal sizes of harvest and of gill net mesh (Table 2). MAXIMUM YIELD - PER - RECRUIT 66 CONDREY ET AL. Effect on yield-per^recruit A yield-per-recruit contour was computed with Ricker’s (1975) expanded form of Beverton’s expression using these estimates, Harrington et ah’s (1979) length-weight relation- ship, and 12 years as an estimate of the maximum attainable age (Figure 3). Sizes of first entry as denoted by legal size limits (Table 2) and average size at entry predicted for gill net mesh Limits arc denoted for the respective states on the plot. The fisheries of most concern are in Florida’s Gulf and Franklin counties and in Louisiana and Mississippi’s recrea- tional Fisheries since these fisheries have no legal minimum limits on the size of first harvest. As such any growth-over- fishing concerns are superseded by the open nature of these fisheries since they are fully exposed to the potential for spawner-recruit overfishing. The situation in Louisiana’s commercial harvest has been greatly improved by two pieces of recent legislation (Ford 1984). The first reduced Louisiana’s gill net mesh from 2.0 in. to 1.75 in., moving the gill net fishery from fish averaging 19.2 in. (6.4 yr, 2.4 lb) to those averaging 17.1 in, (5.0 yr, 1.7 lb). The second increased the minimum legal commercial harvest from 10 in. (2.0 yr, .33 lb) to 12 in. (2.7 yr, .57 lb). On the other hand, Alabama and, perhaps, Texas have recently moved away from maximum yield per recruit. In both slates commercial harvest has been recently prohibited. Before the prohibition the existing regulations targeted the commercial harvest towards tlie size of fish whicli would maximize yield; 3-4 years old, 12-15 in,, and 0.6-1. 1 lb. Given our current estimate of fishing mortality for Alabama, this prohibition will reduce the overall yield for that state, unless it stimulates an increase in the recreational fishery. A similar pattern miglit be expected for Texas, although the situation is less clear as we have no direct estimate of fish- ing mortality for that state. Since the spotted sea trout fishery has a large recreational component, management may be far more concerned with catch-per-angler-hour and spawner-recruit relationships than with yield-per-recruit. Our analysis suggests, however, that efforts to optimize catch-per-angler-hour and to maintain an adequate spawning biomass may be compatible with efforts to maximize yield-per-recruit. Yield appears to be maximized when spotted seatrout are harvested at 3.9 years. This age represents the second year of spawning activity. As such, management that provides for maximum yield- per-recruit, also reduces the danger of spawner-recruit overfishing (as compared to most current regulations), and enhances the recreational experience through the harvest of larger fish. ACKNOWLEDGMENTS We would like to thank the following reviewers for their suggestions: A. M. Bankston, V. Guillory, G. C. Matlock, M. D. Murphy, J. E. Roussel, B. Thompson, G. Waguespack and W. Wiseman. REFERENCES CITED Adkins, G., J. Tarver, P. Bowman, & B. Savoie. 1979. A study of the commercial finfish in coastal Louhmm, Louisiana Pep. of Wild- life and Fisheries Tech. Bull. 29. New Orleans, Louisiana, Adkins, G. & M. J. Bourgeois. 1982. An evaluation of gill nets of various mesh sizei. Louisiana Pep. of Wildlife and Fisheries Tech. Bull. 36. New Orleans, Louisiana. Arnold!, D. 1982. Certain aspects of the life history and habits of the spotted seatrout in Calcasieu Lake. Louisiana. Final report for Dingle Johnson Project Number F-32. Louisiana Dep. of Wildlife and Fisheries, Raton Rouge, Louisiana. Colura, R. L., C. W. Porter, & A. F. Maciorowski. 1984. Preliminary evaluation of the scale method for describing age and growth of spotted seatrout (Cynoscion nebulosus) in the Matagorda Bay System, Texas. Tex. Parks Wildl. Pep., Manage. Data Ser. No. 257. Austin, Texas. Ford, T. B. 1984. Governor's Task Force on Saltwater Finfish Man- agement: Report to the Governor. Louisiana Dep. of Wildlife and Fisheries, Baton Rouge, Louisiana. Harrington, R. A., G. C. Matlock, & J. E. Weaver. 1979. Standard- total length, total length-whole weight, and dressed weight-whole weight relationships for selected species from Texas bays. Tex. Parks WildJ. Pep., Tech. Ser. No. 26. Austin, Texas. Klima, JB. F., & D. C. Tabb. 1959. A contribution to the biology of the spotted ix'eakfish, C}‘noscion nebulosus (Cuvier), from northwest Florida, with a description of the fishery, Fla. Board Conserv. Mar. Res. Lab., Tech. Ser. 30. St. Petersburg, Florida. Lurio, W. J. & W. S. Perret, 1980. Biology and ecology of spotted seatrout {Cynoscion nebulosus Cuvier). Pages 1-13 in: Proceed- ings of the colloquim on the biology and management of red drum and spotted seatrout. Gulf .Slates Marine Fisheries Com- mission, Ocean Springs, Mississippi. Lotio, W. J.. T. Heaton, & O. Dakin. 1980. The relative impact of netting and sport fishing on economically important estuarine species. Mississippi-Alabama Sea Grant Consortium Final Report, MASGP-79-025, Ocean Springs, Mississippi. Matlock, G. C., J. E. Weaver, & A. W. Green. 1978. Trends in finfish abundance in Texas estuaries as indicated by gill nets. Texas Parks and Wildlife Dep., Coastal Fisheries Branch, Austin, Texas. Merriner, J. V, 1980. History and management of the spotted sea- trout fishery. Pages 55 61 in: Proceedings of the colloquim on the biology and management of red drum and spotted seatrout. Gulf States Marine Fisheries Commission, Ocean Springs. Mississippi. Moffett, A. W. 1961. Movement and growth of spotted seatrout, Cynoscion nebulosus (Cuvicr) in West Florida. Fla. Board Con- serv. Mar. Res. Lab., Tech. Ser. 36. 35 pp. NOAA. 1981 . Climatological data: Annual summary, Florida 1980. 84(n);2-3. 1983a. Climatological data: Annual summary, Alabama 1982. 88(13): 11. . 1983b. Climatological data: Annual summary, Texas 7952. 870 3): 3 1-32. Pauly, G. 1979. On the interrelationship between natural mortality, growth parameters and mean environmental temperature in 175 fish stocks./. Cons. Int. I'Explor. Mer 39:175—192. Short Communications 67 Pearson, J. C. 1929. Natural history and conservation of the redfish and other commercial sdaenids on the Texas Coast. Bull U,S. Bur Fish, 44:129-214. Ferret, W. S., J. E. Weaver, R. O. Willbms, P. L, Johansen, T. D, Mcllwain. R. C. RaUlerson, & W. M, Tatum. 1980. Fishery profiles of red drum and sported seatrout. Gulf States Marine Fisheries Commission, Ocean Springs, Mississippi. Ricker, W, E. 1975. Computation and interpretation of biological statistics of fish populations. Bull. Fish. Res. Board Can. 191: 251-259. Stewart. K. W. 1961. Contributions to the biology of the spotted seatrout (Cyfwscion nehulosus) in the Everglades National Park, Florida. Masters thesis, Univ. of Miami, Miami. Florida. Tatum, W. M. 1980. Spotted seatrout (Cynoscion nebulosus) age and growth: data from annual fishing tournaments in coastal Alabama, 1964-1977. Pages 89-92 in: Proceedings of the colloquium on the biology and management of red drum and spotted seatrout. Gulf States Marine Fisheries Commission, Ocean Springs, Mississippi. Trent, L., & P. J. Pristas. 1977. Selectivity of gill nets on estuarine and coastal fishes from St. Andrew Bay, Florida. Fish. Bull. 75:185-198. ADDENDUM (in proof) Since this paper was written, Mississippi and Florida have begun consideration of new regulations that would change the size restrictions in their states. In Mississippi it is probable that state regulations will be changed to make it illegal to sell, offer for sale, or transport for sale in or from the state of Mississippi, spotted seatrout under 14 in. In Florida it is possible that state regulations will be changed to make 14 in. the minimum size limit for spotted seatrout for both commercial and recreational fisheries. The Florida regulation might or might not be applied statewide. If applied statewide in Florida’s recreational and commercial fisheries and applied in Missis.sipprs commercial fisheries, the 14 in. minimum limit would target the harvest towards the size of fish that would maximize yield-per-recruit in these fisheries. On the other hand, if part of Florida remains exempt from this regulation that part, along with the recreational fisheries in Louisiana and Mississippi, will be fully exposed to the threat of spawner-recruit overfishing. Gulf Research Reports Volume 8 | Issue 1 January 1985 Testis-Ova in Spawning Blue Tilapia, Oreochromis aureus B. Clark University of South Florida H J. Grier Florida Department of Natural Resources DOI: 10.18785/grr.0801.10 Follow this and additional works at: http:/ / aquila.usm.edu/ gcr Part of the Marine Biology Commons Recommended Citation Clark; B. and H. Grier. 1985. Testis-Ova in Spawning Blue Tilapia, Oreochromis aureus. Gulf Research Reports 8 (l): 69-70. Retrieved from http;//aquila.usm.edu/gcr/vol8/issl/10 This Short Communication is brought to you for free and open access by The Aquda Digital Community. It has been accepted for inclusion in Gulf and Caribbean Research by an authorized editor of The Aquila Digital Community. For more information, please contact Joshua.Cromwell^usm.edu. Gulf Research Reports, Vol. 8, No. 1, 69-70, 1985 TESTIS-OVA IN SPAWNING BLUE TILAPIA, OREOCHROMIS AUREUS B. CLARK AND H. J. GRIER Department of Biology, University of South Florida, Tampa, Florida 33620 and State of Florida Department of Natural Resources, St. Petersburg, Florida 33701-5095 ABSTRACT Hermaphroditism characterized by the presence of oocytes in the testes is described m the blue tilapia, Oreochromis aureus, for the first lime. Testis-ova were observed in three of 24 spawning males exhibiting otherwise normal male morphology. The testis-ova appeared non-vitellogenic and lacked a follicle cell layer. It is speculated that the testis- ova did not become vitellogenic due to their association will INTRODUCTION Intersexuality characterized by oocytes in the testis has been well documented among teleost fishes (Atz 1964, Reinboth 1970, Borg and van der Hurk 1983, Grout 1983). Testis-ova are often found in individuals which exlubit marked intersexuality with gonads divided into distinct ovarian and testicular regions or possessing intermediate secondary sex characters. However, oocytes in otherwise normal males have been reported (Reinboth 1962, Lillelund Manuscript received December 24,1984; accepted February 25,1985. Sertoli cells and the hormonal environment of the male. 1965). In a study of hermaphroditism among “Mbuna” ciclilids, Peters (1975) suggested that oocytes in a testis was not conclusive evidence for its being a secondary testis. Furthermore, several specimens examined in that study possessed testis-ova yet exlribited male behavior. During a chromosomal analysis of testicular preparations from the blue tilapia, Oreochromis aureus, we observed oocytes in testes of three spawning males. This report offers further evidence for the widespread occurrence of testis-ova among cichlids. To our knowledge, this is the first report of her- maphroditism in O. aureus. 70 Clark and Grier MATERIALS AND METHODS Twenty-four male blue tilapia were collected by cast netting in irrigation canals of the Hillsborough River (Hills- borough County, Florida) during March 1984. Each speci- men received an intraperitoneal injection of 0.1 percent colchicine (Sigma) at a dose of 0.1 nil per 10 grams body weight 6 hours prior to death to accumulate mitotic cells for the chromosomal analysis. Dissected testes were fixed in Bouin’s solution, dehydrated through absolute ethanol, and embedded in glycol methacrylate (Polysciences) (Cole and Sykes 1974). For light microscopy, transverse sections 4 microns thick were stained with toluidine blue. RESULTS AND DISCUSSION AH specimens examined were sexually mature and in breeding condition based on coloration and gonad size. Females possessed mature eggs witiiin the ovary. Some were orally incubating eggs or fry. Histologic examination of the testes revealed active spermatogenesis in all males with numerous meiotic and mitotic figures. In 3 of the 24 males, oocytes occurred among testicular tubules alongside normal spermatogenic tissue (Figure 1), The oocytes (25 to 75 microns in dia- meter) were nonvitelJogenic and often degenerate. In a few, small nucleoli were associated with the nuclear membrane, characteristic of oocytes in the first meiotic prophase (perinucleolar state). Most of the testis-oocytes, however, possessed a single large nucleolus. A distinct follicle cell layer encompassing the testis-oocytes was not present. Sertoli cell processes retained these oocytes within the spermatogenically active tissue of the testis and apparently prevented them from becoming free within the tubule lumen. We speculate that the oocytes did not become viteHogenic because Sertoli cells cannot function as follicle cells, particularly in the presence of male hormones. The Sertoli cells may also be phagocytesing follicular cells. Differentiation of oocytes in testicular tissues remains enigmatic. This phenomenon, however, poses basic questions as to mechanisms of germ cell differentiation and illustrates the variable nature of the teleust gonad. ACKNOWLEDGMENT The authors thank Mr. John Sproukin for cast netting the blue tilapia. REFERENCES CITED Au, J. W. 1964. Inteisexuality in fishes. Pages 145 232 in: C. N. Armstrong and A. J. Marshal! (eds.), Intersexuality in vertebrates including man. Academic Press, New York. Borg, B., & R. van der Hurk. 1983. Oocytes in the testes of the Ihree-spined stickleback, Gasterosteus aculeatus. Copeia 1983: 259-261. Cole, M. B., &. S. M. Sykes. 1974. Glycol methacrylate in light microscopy: A routine method for embedding and sectioning animal tissues. Stain Technol. 49:387-400. Grout, D. E. 1983. A case of hermaphroditism in the rainbow Smelt, Osmerus mordax. Copeia 1983:812-813. Lillelund, K. 1965. Weitere Untersuchungen ilber den Hermaphro- ditismus bei Osmerus eperlanus (L.) aus der Elbe. Z. Morph. Okol. Tiere 55 :410-424. Peters, H. M. 1975. Hermaphroditism in cichlid fishes. Pages 228- 235 in: R. Reinboth (cd.). Intersexuality in the animal kingdom. Springer-Verlag, New York. Reinboth, R. 1962. Morphologishc and funktionelle ZweigeschlechL- Uchkeit hei marinen Teleostiern (Senanidae, Sparidae, Centra- canthidae, Labridae). Zoo/. Jb. Physiol 69:405-480. 1970. Interscxuality in fishes. Pages 515-543 in: G. K. and J. G. Phillips (eds.), Hormones and the environment. 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