DISTRIBUTION OF ENCRUSTING FORAMINIFERA AT MAYAGUANA, BAHAMAS: DETERMINING ASSEMBLAGE COMPOSITION AND RELATIONSHIP TO FOOD AVAILABILITY
The objectives of this actualistic study was (1) to see if the same pattern of distribution occurs at Mayaguana, located some 215 km southeast of San Salvador, and (2) to take water and sediment samples to see if food availability could be involved in the distribution noted. We sampled 7 sites representing a range of environments and collected 6 cobbles per site. We used syringes to take 20-ml water samples under each cobble and collected 100-ml samples of sediment under the cobbles where possible.
As predicted based on past research, (1) cobbles at the mid-shelf patch reef have a diverse assemblage dominated by Planorbulina; (2) the bank barrier reef site is Homotrema-rich, including a notable amount of the globular morphotype along with erect Carpenteria and sparse, relatively small Gypsina plana; and (3) cobbles at the wall site at the platform margin (water depth: 22m) are dominated by large Gypsina plana. Homotrema are few and are very small. Assemblages at one of the near-shore sites are dominated by Homotrema and Nubecularia as we have seen previously; another site has a higher than expected percentage of Planorbulina and relatively few Homotrema. Two additional sites can be described as mid-shelf shoals, an environment not previously encountered by our research team. In these offshore, shallow-water (1-2m) sites, foraminifera can be very dense and are dominated by Homotrema. Meiofauna and microbial remains in the water and sediment samples are currently being analyzed.