Abstract Methods Restricted Interior Environment Foraminiferal Distribution Current Transport Conclusions Acknowledgments Literature Cited Appendix

The benthic foraminiferal fauna inhabiting Florida Bay, a specialized restricted platform-interior environment, is composed of subfaunal assemblages that are diagnostic of topographic/environmental variations within the bay. Similar subfaunal assemblages may be typical of other severely restricted carbonate embayments. In Florida Bay, numbers of individuals and numbers of species are less variable in areas of uniform bottom topography than in those with changing relief. Local irregularities in bottom relief (patch reefs, basins, mudbanks, or shorelines) influence local distribution and frequency. Winnowing and sorting by currents, winter storm winds, and flood tides have local influences on the population but do not physically affect the regional integrity of a subfaunal assemblage in relation to its subenvironment.

Benthic foraminifera of the south Florida carbonate province are dominated by species belonging to the Soritidae and Miliolidae, with those of the Rotaliidae, Elphidiidae, Amphisteginidae, Ataxophragmiidae, and Textulariidae following in order of decreasing abundance. Pelagic species are extremely rare. The best environmental index to foraminiferal distribution in shallow-water carbonate sediments is water circulation. As a rule, individual foraminifera are most abundant in protected areas with calm water conditions and least abundant on the platform margin, the zone of highest and most constant wave energy, suggesting that the condition of being sheltered is the requisite for habitat selection. Specimen frequency generally decreases in an offshore direction, whereas frequency of species generally increases offshore and is highest in areas transitional between major environments.

Although families, genera, and species of foraminifera may be different in sediments of different ages, distribution patterns in relation to platform features should be evident. There should be systematic changes in faunas near a platform margin, regardless of age, in response to physiographic-hydrographic gradients. In ancient limestones, the stratigrapher may use similar changes empirically without assigning the fossils to narrow taxonomic units or understanding the precise ecologic significance of the changes. Once the patterns of distribution for faunal assemblages are established relative to a given platform and its margin, they may become a useful predictive tool that can be applied empirically to infer direction of, and proximity to, the paleoplatform margin as well as to other features on the platform.