Ecological effects of harmful algal blooms on the wildlife communities associated with submerged aquatic vegetation. Progress report: July 1 - December 31, 2006.

Abstract

Seagrass habitats are highly productive and ecologically rich areas for estuarine fish and bird species. Among all the sources of stress to seagrass habitats, harmful algal blooms (HABs) are ranked in the highest category. HABs are a source of ecological disturbance that are thought to alter water quality (physical and chemical), species composition, and patterns of primary productivity in seagrass meadows. This project will investigate the extent to which red tide affects the local abundance and habitat use of individual species, and composition of the fish and avian communities utilizing submerged aquatic vegetation habitats in Sarasota Bay. Data will be obtained by conducting seasonal surveying of fish (purse seining) and bird communities (visual surveys) during periods of red tide and in the absence of red tide. Our study design will include surveys of (I) fishes, (2) birds, (3) K. brevis cell counts, and (4) water quality (dissolved oxygen, salinity, temperature). Surveys conducted in summer 2006 have been completed and preliminary data analysis performed. Abundance and diversity of fish associated with the seagrass community rebounded following the major red tide disturbance of 2005. A smaller red tide event began in early August 2006. This red tide event appeared to coincide with increases in the local abundance of some bird (gulls) and fish (clupeids) species, but also corresponded with a decrease in fish diversity. This is the first interim report for this three-year project. Thus, results are preliminary. However, much progress has been made in the first six months of the project and we are confident that our proposed methods will allow us to test all of the hypotheses outlined in the grant application.