Temporal and Spatial Trends in Zooplankton Communities along a Potential Eutrophic Gradient in a Subtropical Lagoon.
Abstract
The estuarine waters of Merritt Island National Wildlife Refuge (MINWR) are currently managed as a no-take fisheries reserve (NTR) and have historically demonstrated higher adult fish density and biomass compared to adjacent fished areas. In an ongoing study, however, this same area has shown dramatically lower densities of larval fishes. It was suspected that higher anthropogenic nutrient loading outside the NTR may locally stimulate zooplankton production and increase larval fish survival here by minimizing starvation. This scenario was examined by quantifying the density of four common zooplankton taxa between reserve and non-reserve areas on two separate dates in May and July 2003. Our results suggest that the abundance of most zooplankton taxa were higher in July and while the highest densities of important species such as copepods were seen in eutrophic regions of MINWR (up to 20814/m3), reserve areas often showed an increase in densities as well. These initial results suggest that while food resources may be higher outside reserve, the differences may not be of a magnitude to alone cause the spatial disparity observed in larval fish abundance.
Sampling Regions
Zooplankton sampling regions included four sub-basins within the 52 km stretch of the Banana River Lagoon located between Merritt Island and Cape Canaveral, Florida (Figure 1). The Upper Banana River (UBR) north of S.R. 405 causeway is a no-take fisheries reserve and public access has been prohibited since 1962. The Middle Banana River (MBR) between S.R. 405 and S.R. 528 has been designated a no-motor zone (NMZ) since 1990. The Lower Banana River (LBR), south of S.R. 528 has no access restrictions and is subject to greater anthropogenic pressure, primarily due to high residential development. Samples were also collected from Southern Mosquito Lagoon (SML), 8 km north of the Banana River.
Copepod Density
Above: There were significantly higher densities of copepod during the July sampling trip versus the May sampling trip. The densities were higher in the UBR and the LBR for both May and July. The highest densities were in the LBR in July.
Author: Laura Begay, Ecology Emphasis Group
South Mountain Community College, Phoenix, AZ
Principal Investigator: Eric Reyier, Dynamac Corporation
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