Master’s Thesis Proposal Seminar

Abstract

The role of fish in nutrient concentration in an oligotrophic subtropical estuary

There are examples from all over the world of the use of artificial structures to induce movement of fauna for many different species. The literature suggests that the presence of an artificial structure in a seagrass bed will serve as an attractant for fauna of neighboring regions. Previous experiments using artificial structures near coral reefs in the Bahamas have shown that these structures can induce the presence of different species of fish. The attraction of these species to structure in turn brought nutrients whose deposition resulted in the presence of a concentric seagrass bed around the structure becoming less dense as one moved away from it. The importance of these experiments lie in the fact that the seagrass growth occurred in regions that were formerly inhabited only with sparse macroalgal and seagrass shoots. It has been thus hypothesized that the growth of the new seagrass bed took place due to the nutrient addition from the presence of the fish. This manipulation can have similar effects in other oligotrophic regions where structure for fish aggregation is not present.

The Florida Bay is an oligotrophic basin with seagrass beds that lack structure to encourage fish congregations. It is also home to a number of fish species that feed on benthic invertebrates in seagrass beds and aggregate around structure for shelter and protection. Nutrient addition by bird colonies has been shown to alter the density and species composition of seagrass bed in different parts of the Florida Bay. This leads to the question: do fish aggregations around structure result in nutrient additions that also result in differences in species composition and species density?