Document Type

Internship Report

Publication Date

Fall 2012

Abstract

The University of Miami Benthic Ecology Research Lab has been monitoring and mapping submerged aquatic vegetation (SAV) for the central and southern portions of Biscayne Bay as part of the Comprehensive Everglades Restoration Plan (CERP) since 2003. This project evaluates the role of salinity and nutrients on the abundance and distribution of seagrasses within permanent water quality stations operated by Biscayne National Park. Specifically, this experiment was designed to determine if the presence of seagrass species is an artifact of nutrient deposition rather than salinity regime. Offshore sites within this network of loggers are typically unaffected by major fluctuations in salinity from terrestrial freshwater sources, yet display seagrass community structure dynamics inconsistent with current salinity patterns (i.e., these sites are dominated by species that are not expected based on salinity regimes). We also determined that with contributions of waterfowl nutrients to the water column, nutrients may be acting as the dominant driver for seagrass population dynamics. At sites with large marker buoys, we found T. testudinum biomass with a greater percent phosphorus content (sig. p <0.0001) near the buoy than biomass collected farther than 6 m away. H. wrightii coverage was limited offshore (only present in halo near buoy), and nutrient variation was limited through the experiment (inshore to offshore and near and far from buoy). However, weight per blade exhibited higher nutrient availability at offshore buoyed sites. Based on these preliminary results of the data, we can generally conclude that nutrient deposition impacts seagrass community structure. This information has the potential to greatly improve SAV data resolution for BNP and more accurately describe seagrass community structure.

Comments

Department: MBF

MPS Track: TME

Location: Marjory Stoneman Douglas, Biscayne Nature Center (Key Biscayne, FL); Lirman Laboratory, RSMAS

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