Distribution of Recent Benthic Foraminifera on Varying Substrates on the Southeast Florida Reef Tract

Benthic foraminifera are abundant sediment forming organisms found in South Florida. The distribution of benthic foraminifera was correlated with substrate type on a marginal shallow water reef system off Pompano Beach FL. The study area is a small segment of the southeast Florida reef tract that includes the nearshore ridge complex and the middle reef. The ridge complex composition varies seaward with coral rubble and cemented coral fragments. The middle reef consists of an acroporid reef framework.

A total of ten samples were collected between January 2014 and April 2015 across 5 different substrates (1) loose rubble 3-5m (2) cemented rubble 4m (3) pavement 3.5m (4) loose rubble 8m and (5) linear reef 10m. Well preserved foraminifera were picked and identified with a total of 32 genera and 42 species. Dominant species include the heterotrophic taxa Quinqueloculina spp. and symbiont taxa Archaias angulatus and Laevipeneroplis proteus. Overall, opportunistic taxa were scarce specifically Ammonia spp. Elphidium advenum, Elphidium discoidle, and Bolivina pulchella.

The concentrations of species found at each habitat are contingent upon the type of substratum within their environments. Substrate 2 located on the ridge complex had the highest concentration of total species and highest concentration of heterotrophic taxa. Substrate 3 on the crest of the ridge complex had the second highest total concentration. Substrate 2 and 3 had the highest concentrations of symbiont-bearing taxa and consisted primarily of pavement and cemented rubble. Moderate concentrations of both symbiont bearing and heterotrophic taxa were found at loose rubble substrates 1 located on the ridge complex and 4 located on the outer portion of the ridge complex. Substrates in depths greater than 8m approaching the middle reef had the lowest concentration of total species. High percent abundances appear to be within depths of 3-5m and are associated with either pavement or cemented rubble. Lower species abundances may be attributed to the physical properties of the rubble substrate, depth, or proximity to the shoreline.