An Ecological Characterization of the Tampa Bay Watershed
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Biological Report 90(20) December 1990 An Ecological Characterization of the Tampa Bay Watershed Fish and Wildlife Service and Minerals Management Service u.s. Department of the Interior Chapter 6. Fauna N. Scott Schomer and Paul Johnson 6.1 Introduction on each species, as well as the limited scope.of this document, often excludes such information from our Generally speaking, animal species utilize only a discussion. Where possible, references to more limited number of habitats within a restricted geo detailed infonnation on local fish and wildlife condi graphic range. Factors that regulate habitat use and tions are included. geographic range include the behavior, physiology, and anatomy ofthe species; competitive, trophic, and 6.2 Invertebrates symbiotic interactions with other species; and forces that influence species dispersion. Such restrictions may be broad, as in the ca.<re of the common crow, 6.2.1 Freshwater Invertebrates which prospers in a wide variety of settings over a Data on freshwater invertebrate communities in va.')t geographic area; or narrow as in the case of the the Tampa Bay area are reported by Cowen et a1. mangrove terrapin, which is found in only one habitat (1974) in the lower Hillsborough River, Cowell et aI. and only in the near tropics of the western hemi (1975) in Lake Thonotosassa; Dames and Moore sphere. Knowledge of animal-species occurrence (1975) in the Alafia and Little Manatee Rivers; and within habitat') is fundamental to understanding and Ross and Jones (1979) at numerous locations within managing fish and wildlife resources. Consequently, the basin. Selected species or higher taxa that have the major thrust of our discussion of the fauna of the been studied include the freshwater grass shrimp Tampa Bay watershed is concerned with document Palaemonetes paludosus (Beck 1974); the mayflies ing which animal species tend to occur in which (order Ephemeroptera) (Berner 1950); the dragonflies habitat.;;, Lewis and Estevez (1988) have a much 1930); more thorough examination of the marine aspect') of (order Odonata) (Beyers and the water beetles the area in their estuarine profile ofTampa Bay. (order Coleoptera) (Young 1954). It would obviously also be useful to know how, Other invertebrate studies, though not occurring when, and why a particular habitat is used by a given within the basin, should also be noted. They are species. At what life stage(s) doe.'llhe animal use a useful because oftheir proximity to the study area and given habitat and for what purpose (i.e., nesting, the similarity ofthe ecological processes investigated reproduction, feeding, roosting, aestivation, as pupae, on area water bodies. Such studies include those of lalVae, juveniles or adults)? Is habitat use continuous Lanquist (1953) and Ware and Fish (1969) in the by one or another species or is it restricted to certain Peace River Basin following phosphate slime spills. seasons, certain times of the day, or only certain Important plankton studies in nearby systems were sublocations within the habitat (e.g., canopy, tree made by Maslin (1969), Reid and Blake (1969), bark, soil litter, benthos, plankton)? Nordlie (1976) and Shiremall<h'1d Martin (1978). Though these details may be essential to the Cowell et aI. (1974) sampled five stations in the management of a species, the lack of this knowledge lower Hillsborough River for invertebrate fauna, each 216 6. Fauna station having a mixture ofbottom types, vegetation, small-bodied herbivores. A total of 23 species of physical environments (pools, ponds, runs), and rotifers, 5 of copepods, and 6 of cladocerans are resulting current structures. Ofthe 143 taxa recorded, recorded. Species diversity was lowest in January, 122 were insects, with Diptera (32 taxa), Odonata (28 August, and September. Of the six cladocerans, taxa), and Coleoptera (26 taxa) being the most Bosmina longirostris was the most common, common orders. In quantitative benthic samples, comprising 93% ofthe total. oligochaetes, mollusks, and chironomids account for Rotifers were the only group to exhibit significant 37.6%, 32.6%, and 25.7% of the total fauna, respec horiwntal spatial patchiness in species composition. tively. Densities in this study range from 25 to 3,303 This patchiness correlated well with increasing water 2 organisms/m . depth. At the same time, rotifer abundance showed a Similar numbers oftaxa (49-52) were recorded at consistent decrease with depth at each station, while the four river stations, with many taxa occurring at copepod and cladoceran numbers tended to increase. more than one station. Samples taken in a Sphagnum Rotifers represented 90.3% of the individuals bog off the river yielded 25 taxa, 13 of which were sampled, copepod nauplii 7.8%, and adult copepods found nowhere else in the river system. In general and cladocerans only 1.9%. Rotifer populations mayflies, mollusks, and dragonflies (Odonata) were exhibited three distinct peaks during the year, one in more numerous at upstream swamp forest stations, winter, another (the largest) in late spring, and the while damselflies (Odonata) and chironomids third (the smallest) in late fail. Each population peak (Diptera) were more abundant downstream, espe was dominated by different species. In winter the cially in vegetation. As in the Peace River, the intro dominant species were Polyarthra vulgaris, Keratella duced pelecypod mollusk Corbicula manilensis was cochlearis, Conochiloides dossuarius, and abundant in the HillsboroughRiver. Corbicula is also Anuraeopsisfissa. In late spring, seven species-K. abundant in the upper reaches of the Manatee River serrulata, Brachionus angularis, B. calyciflorus and estuary (Culter and Mahadevan 1982). Hexarthramira in addition to the first three above The effect ofvegetation on invertebrate densities, dominated, making up 96% ofthe total. The late fall though difficult to compare quantitatively, is quite peak was dominated by P. vulgaris, A. lissa, apparent in the data. Cowell et al. (1974) estimated a Syncheata stylatam, Trichocera simi/is, B. 10- to 100-fold greater density oforganisms collected havanaensis, and Microcodon clavus. Copepod in vegetation than in benthic samples. In the Egeria populations showed typical spring and fall peaks. Hydrilla community, Beck (1974) estimated 3 x lOS Cladoceran populations peaked in the spring only, an to 11 x lOS grass shrimp per hectare, and Barnett event totally dominated by Bosmina longirostris. (1972) estimated 2 x lOS to 4 x lOS mostly forage fish per hectare. These values are 2 to 3 orders ofmagni Benthic invertebrates in Lake Thonotosassa were tude higber than values from adjacent areas with no numerically dominated by oligochaetes (primarily vegetation. tubificid worms--commonly called sewer worms because they flourish in the highly eutrophic sedi The species composition of the communities ments ofsewers) (69.7%) and chironomids (24.7%). varies as well. In the shaded, fast-flowing reaches of Shallow (i.e., better oxygenated) stations generally the upper river, the Vallisneria grass-bed community yielded more invertebrate taxa than did deeper sta is animportant source ofinvertebrates selVing as food tions. Creek stations exhibited the most taxa as well for fish. Areas dominated by Ludwigia and Polygo as the highest density ofindividuals (36,340/m2). The num also showed high densities of invertebrates, deepest station exhibited the lowest recorded density while Pontederia and Paspalum contained relatively (l,581/m2). Density of individuals at creek stations few taxa and lower densities. appeared to be lX'sitively correlated with the presence Cowen et a1. (1974) reponed a zooplankton of organic effluent from sewage treatment plants. community in Lake Thonotosassa dominated by The only station not directly influenced by effluent 217 Tampa Bay Ecological Characterization showed significantly lower densities, especially of plankton in upper Tampa Bay. Hopkins (1973) tubificid worms, than other stations (Dye 1972; presents a general review of zooplankton in the east Cowell et al. 1974). ern Gulf of Mexico, and Turner and Hopkins (1985) and Weiss and Phillips (1985) review zooplankton The prevailing trends in zooplankton and benthic and meroplankton studies, respectively, in Tampa invertebrate communities lead Cowell et al. (1974) to Bay in particular. The most authoritative study of characterize the lake as eutrophic. Dominance of Tampa Bay zooplankton, however, is reported by zooplankton by small-bodied rotifers, the occurrence Hopkins (1977). of blue-green algae, high rates of productivity, and significant oxygen deficits in the summer hypolim Quarterly samples at 42 stations within the bay nion all point to this conclusion. Dominance of the yielded 37 taxa of true planktonic (haloplankton) benthos by oligochaetes and two species of chirono organisms (Hopkins 1977). These were divided into mids, Glyptotendipes paripes and Chironomus cras three categories based on numerical abundance; sicandatus, also support this conclusion. These taxa group 1 (>1,OOO/m3), group 2 (100-1,OOO/m3), and have been linked to eutrophic conditions in other group 3 «lOO/m3). Florida lakes receiving organic wastes and nutrient Group 1 consisted of four species, the cyclopoid runoff(provost 1958; Provost and Branch 1959; Beck copepod Oithona colcarva (=0. breviconus), the and Beck 1969). calanoid copepods Acartia tonsa and Paracalanus In the Alana and Little Manatee Rivers, freshwater crassirostris, and a tunicate, Oikopleura dioica. benthic faunas begin