SOFIA - Diagnostic Foraminiferal Assemblages of Florida Bay and Adjacent Shallow Waters: A Comparison

Samples were collected by hand from the upper few centimeters of bottom sediment from 46 locations selected along traverses which cross the various types of depositional environments within Florida Bay. Traverses A, B, and D (39 samples) transect the bay; traverse C (7 samples) crosses the platform margin (Fig. 1). Foraminifera greater than 62 um were identified (Appendix) under the binocular microscope from approximately 10 cc of washed material, and their abundance was estimated: 4 = rare; 8 = few; 16 = numerous; 50 = common; 100 = abundant; 200 = very abundant; 500 = dense. Only tests of free-moving forms were studied; encrusting forms such as Homotrema rubrum were not considered in this study.

Simple statistics were computed for each sample: total fauna per gram of examined residue, number of species, number of genera, percent frequency of constituent species, and percent frequency of constituent families. These figures are approximate, inasmuch as species abundance was estimated. Most frequencies by actual count of random samples were within 10% and all were within 20% of the percent frequency based on approximations. This precision was considered sufficient for the 'broadview' purpose of this study. All data were transferred to diagrams summarizing general patterns for foraminiferal distribution and sediments across the platform (Figs. 2, 3). Figures 4 through 9 show (a) distribution of families, genera, and species in relation to directly measured geographic location, bottom topography, percent mud, dominant species, depth, and sediment type, and (b) estimated physiography, water circulation, and bottom topography based on diver observations.

index map showing mudbank topography and locations of sample stations along Traverses A-D in Florida Bay

Figure 1. Index map showing mudbank topography (lightly stippled areas within bay) and locations of sample stations along Traverses A-D in Florida Bay. Base map adapted from U.S. Coast and Geodetic Survey hydrographic chart. Contours in fathoms (1 fathom = 1.83 m). [larger image]

General Distribution Patterns of Foraminifera and Sediments Across a Typical Platform		Distribution Patterns of Foraminifera in a Carbonate Embayment (Florida Bay)
Figure 2. Idealized summary of distribution patterns of foraminifera and sediments across a typical platform. Interpretation based on relations observed in the Florida Bay data set. Illustrated foraminiferal tests of diagnostic species belonging to the four most dominant families are as they would appear in oriented thin sections. [larger image]		Figure 3. Idealized summary of distribution patterns of foraminifera in the restricted interior environment of a carbonate embayment. Date based on samples from Florida Bay. Illustrated foraminiferal tests of index species are as they would appear in oriented thin sections. (M) = miliolids. [larger image]

Percentage Distribution of Foraminiferal Groups
Traverse A Mainland south across Florida Bay [larger image]	Traverse B West-east axis of Florida Bay [larger image]
Figure 4. Distribution and abundance of significant foraminiferal families and arenaceous species along Traverses A and B in Florida Bay. Bathymetric profiles shown in Figures 5 and 6.

Traverse A - Florida Bay		Traverse B - Florida Bay
Figure 5. Diagram showing number of species, abundance, distribution, and faunal variety at each sample station in relation to physiography, bottom topography, and depth along Traverse A. [larger image]		Figure 6. Diagram showing number of species, abundance, distribution, and faunal variety at each sample station in relation to physiography, bottom topography, and depth along Traverse B. [larger image]

Traverse C to Platform Edge		Traverse D - Cross Bank
Figure 8. Diagram showing number of species, abundance, distribution, and faunal variety at each sample station in relation to physiography, bottom topography and depth along Traverse C. [larger image]		Figure 9. Diagram showing number of species, abundance, distribution, and faunal variety at each sample station in relation to physiography, bottom topography, percent mud, and depth along Traverse D (Cross Bank). During periods of prevailing winds, windward side of island is to north, leeward to south. [larger image]

Methods