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Baseline Assessment of Guanica Bay, Puerto Rico in Support of Watershed Restoration

This project began in April 2009 and was completed in May 2014

We completed a baseline assessment of the environmental conditions in Guanica Bay, Puerto Rico, to help coastal managers identify the most appropriate restoration projects, and their effectiveness, in support of the area’s watershed restoration efforts. We mapped the ocean floor, surveyed the fish and other seafloor creatures, and measured contaminants in sediments and corals, nutrient levels in surface waters, and sedimentation rates at coral reef sites.

Why We Care
Coastal managers have been considering/implementing a variety of watershed restoration projects to reduce the amount of pollution reaching Guanica Bay. Pollution running off the land and into coastal waters threatens Puerto Rico’s coral reef ecosystems and fishery habitats. Watershed restoration projects, such as stream bank stabilization, lagoon restoration, wastewater treatment plant improvements, and enhanced agricultural management practices can help by capturing polluted water before it reaches the reef.  In addition to providing our restoration partners information to better understand where the contaminants are coming from and the potential impact of those contaminants to the reef, data from this project provides a baseline against which to measure the success of the restoration effort.

What We Are Finding
This study contains several important findings.  First, we report unusually high, and almost certainly toxic, levels of PCBs in the northeast portion of the Bay.  This has implications for ecosystem health, but could also affect fisheries and therefore human health.  Numerous contaminants were also detected in the tissues of mustard hill coral in the waters offshore from the Bay.  Finally, data also suggests that the watershed is a major source of nutrients to the Bay and offshore waters.

What We Are Doing
We sampled the sediment inside the Bay and the nearshore areas and coral tissues.  These samples were chemically analyzed for 162 contaminants, including heavy metals, pesticides, hydrocarbons, and other pollutants; sediment and coral tissue analyzed. From 2009 to 2012, surface water nutrients and sedimentation (via sediment traps) were measured once a month.  In addition, we produced a new map of marine habitats, identifying features such as coral reefs, seagrass beds, and mangroves. As part of the project, we collected baseline information on fish communities and benthic organisms living in these habitats.

Next Steps
This project has been completed.  All contaminant data is available via the National Status and Trends data server.  Both local and federal management agencies have notified of unusually high sediment PCB concentrations and any subsequent remediation actions fall under their purview.

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