Contaminants Assessments in the Coral Reefs of the Virgin Islands National Park and Virgin Islands Coral Reef National Monument

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Coral reefs around the world are exposed to a number of environmental contaminants. USGS researchers investigate the issue of contamination on the reefs around the U.S. Virgin Islands.

 

Detritus sampling from coral reef - WARC

Detritus sampling from coral reef

The Science Issue and Relevance: A large and growing body of literature has documented declines in living coral and presented potential factors that may be driving the changes on Caribbean coral reefs. A much publicized stressor of corals in the Caribbean was the increased sea surface temperature event that occurred most recently in 2005. Months later widespread coral bleaching was followed by disease and, in some cases, mortality. Additionally, coral reefs around the world are exposed to a variety of environmental contaminants, some of which are proven endocrine disruptors, immunosuppressors, and/or toxins that can stress corals and other reef organisms. Until recently, the impact of environmental contaminants on reefs around the U.S. Virgin Islands has received relatively little attention. We have been conducting projects to begin addressing the issue of contamination in Virgin Islands National Park (VIIS) and Virgin Islands Coral Reef National Monument (VICR).

Methodology for Addressing the Issue: The first project addressing the issue involved analysis of samples collected from five different matrices (living coral tissue, fish, plankton, detritus, and water) at four different reef locations within the VIIS and VICR (see publications tab). The second project involved analysis for organotin compounds in sediment samples collected from one bay within the VICR (see publications tab). The current project is focused on two aspects of water quality. The first is measurement of nutrient enrichment in bays of the VIIS, and tracing detected enrichment to potential sources on the island. Nitrogen isotope ratios were measured in macroalgae to assess enrichment, while certain contaminant indicators were measured to identify potential causative factors for the nutrient enrichment. Data from the sampling effort will be used by the VIIS to reduce nutrient impacts within VIIS waters. The second aspect is measurement of sunscreen compounds in VIIS waters (see product 1 below). Some sunscreen chemicals are known to cause endocrine disruption in a variety of organisms and cause bleaching in coral.

Threespot Damselfish (Stegastes planifrons) - WARC

Threespot Damselfish (Stegastes planifrons)

Future Steps: The sunscreen chemical benzophenone-3 was found in VIIS waters at concentrations approximating the highest reported in the literature.  As a result, we are planning exposure studies with fish to measure their response as an indicator of effects that may be occurring in fish of VIIS coastal waters as a result of their exposure to this chemical.

Products (also, see Publications tab):

  1. Tributyltin (TBT) Contamination in Sediments of Otter Creek Bay, Virgin Islands Coral Reef National Monument – final report to Virgin Islands National Park.