Swanson, 1964; Kissling, 1965), they are rare 

 or absent in the channels of northwestern 

 Florida Bay (Tabb and Manning, 1961). 



Within the seagrass areas of Porpoise Lake 

 that are superficially homogeneous, several 

 animals had discontinuous distribution. The 

 finger coral ( Porites po rites var. furcata ), 

 the American star-shell ( Astraea tecta 

 americana ), and the long-spine d star- shell 

 (A. phoebia ), were along the southern bank but 

 not the northern bank of this basin. We did not 

 see these species in central Florida Baynorth 

 of Porpoise Lake, nor did Tabb and Manning 

 (1961) report them from northwestern Florida 

 Bay. These species are common, however, on 

 the Atlantic side of the Florida Keys (Voss and 

 Voss, 1955; Kissling, 1965). 



Ginsburg (1956) observed that organisms 

 which inhabit the reef tract ^ paralleling the 

 Atlantic side of the Florida Keys maybe abun- 

 dant in the outer or marginal zone of Florida 

 Bay where there is tidal exchange with the 

 reef tract and where salinities are near "nor- 

 mal." Furthermore, Turney (1964) found the 

 distribution of mollusks in Florida Bay to be 

 related primarily to water circulation, and 



he cited Aj americana (A^ tecta americana ) 

 as a characteristic species of the Atlantic 

 margin of Florida Bay, an area of frequent 

 exchange of water with the Atlantic Ocean. 

 This tidal water extends into the southern 

 portion of Porpoise Lake (Mc Galium and 

 Stockman, 1964) and meets the slowly circu- 

 lating waters of the inner bay which hiave fluc- 

 tuating salinities and temperatures (Gorsline, 

 1963). 



Different masses of water have dissimilar 

 ecological effects and support distinctive popu- 

 lations of organisms (Phleger, 1964; Gerame- 

 Vivas and Gray, 1966). Water movements in 

 Florida Bay produce separate water masses 

 that have unlike characteristics (Gorsline, 

 1963). Within Porpoise Lake, animal asso- 

 ciates of the seagrass beds differ from those 

 of the adjacent channels. These abrupt vari- 

 ations in fauna suggest the effects of ex- 

 tremely local habitats that cannot, necessarily, 

 be attributed to different water masses. The 

 general distribution of organisms in the lake 

 and in Florida Bay, however, defines varied 

 environments created or influenced by different 

 water masses. 



ACKNOWLEDGMENTS 



The following specialists identified speci- 

 mens, made reference material available, and 

 helped us resolve many taxonomic problems: 

 From the Bureau of Gomnnercial Fisheries, 

 Frederick H. Berry (fishes), Richard J. Daly 

 (fishes), George G. Miller (fishes), and Garl H. 

 Saloman (crustaceans); and from the Rosenstiel 

 School of Marine and Atmospheric Sciences, 



Frederick M. Bayer (mollusks), Anthony J. 

 Provenzano (hermit crabs), G. Richard Robins 

 (fishes), Martin Roessler (fishes), Wesley L. 

 Rouse (crustaceans), Durbin G. Tabb (crus- 

 taceans), Lowell P. Thomas (echinoderms), 

 Jervis W. Wacasey (polychaetes), and Robert G. 

 Work (mollusks). 



LITERATURE CITED 



ALLEN, DONALD M,, and ANTHONY INGLIS. 

 1958. A pushnet for quantitative sampling 

 of shrimp in shallow estuaries. Limnol. 

 Oceanogr. 3: 239-241. 



GERAME-VIVAS, M. J., and I. E. GRAY. 



1966. The distributional pattern of ben- 

 thic invertebrates of the continental 

 shelf off North Garolina. Ecology 47: 

 260-270. 



GOSTELLO, T. J., and DONALD M. ALLEN. 

 1966. Migrations and geographic distribu- 

 tion of pink shrimp, Penaeus duo r a rum , 

 of the Tortugas and Sanibel grounds, 

 Florida. U.S. Fish Wildl. Serv., Fish. 

 Bull. 65: 449-459. 



GINSBURG, ROBERT N. 



1956. Environmental relationships of grain 

 size and constituent particles in some 

 south Florida carbonate sediments. 

 Bull. Amer. Ass. Petrol. Geol. 40: 

 2384-2427. 



Ginsburg defined the reef tract as "the arcuate band- 

 shaped area east, southeast, and south of the Keys between 

 and 300 feet." 



GORSLINE, DONN S. 



1963. Environments of carbonate deposition 

 Florida Bay and the Florida Straits, hi 

 Shelf carbonates of the Paradox Basin, 

 pp. 130-143. Four Gorners Geol. Soc, 

 Fourth Field Gonf. Symp. 



HOESE, H. D., and R. S. JONES. 



1963. Seasonality of larger animals 

 in a Texas turtle grass community. 

 Publ. Inst. Mar. Sci. Univ. Tex. 9: 

 37-47. 



KISSLING, DON L. 



1965. Goral distribution on a shoal inSpan- 

 ish Harbor, Florida Keys. Bull. Mar. 

 Sci. 15: 599-611. 

 McCALLUM, J, S., and K. W. STOGKMAN. 



1964. Water circulation, bi, R. N, Ginsburg 

 (editor), South Florida carbonate sedi- 

 ments, Guidebook Field Trip No. 1, 

 pp. 11-13. Geol. Soc. Amer. Annu. 

 Conv. 



MOORE, DONALD R. 



1963. Distribution of the sea grass, Tha- 

 lassia , in the United States. Bull. Mar. 

 Sci. Gulf Garib. 13: 329-342. 



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