The abundance, distribution and biogeochemistry of marine plants and algae in Biscayne Bay, Florida

Background/Question/Methods

Biscayne Bay is a semi-enclosed estuary that lies on the southeastern end of the Florida peninsula just north of the Florida Keys. This estuary is bordered by metropolitan Miami to its north and northwest, the Florida reef tract to the east, and intermitting natural and developed shorelines to its west. Biscayne Bay provides a number of goods and services to the local population. Unfortunately, this service provision exposes this system to anthropogenic impact. We report the initial results of a multi-stage project which seeks to increase our ecological understanding of the primary producers in this system. Our main objective is to characterize the ecology of this system’s main primary producers in order to create ecologically relevant policy for their protection in the future. We undertook a survey of the species-specific variation of marine plants and algae across the bay, and also investigated relationships between this variation and the benthic and foliar biogeochemistry.  We surveyed 190 sites on SCUBA using a modified Braun-Blanquet technique to estimate species distribution, and abundance of the primary producer community and the benthos. Sediment cores were also taken at each site for processing to determine benthic concentrations of carbon, nitrogen and phosphorus. 

Results/Conclusions

We report that Biscayne Bay, Florida is largely dominated by Thalassia testudinum. The coastlines are populated by alternating T. testudinum and Halodule wrightii beds. The areas surrounding the reef tract either have mostly T. testudinum beds or a T. testudinum and Syringodium filiforme mixed bed. Calcareous green algal species maintained sparse populations both within the bay and on the reef tract. Early results also indicate that areas with higher benthic nitrogen concentrations drive communities that are largely dominated by calcareous algae (mainly different species of Halimeda and Batophora). Slowing growing species of seagrasses were more abundant in more oligotrophic environments.  Understanding the distribution and abundance of seagrasses and algae within the bay can aid management in making decisions concerning their protection and restoration.