There are many sources of pollution in the VI, originating from both land and marine activities. Pollutants include trash that is not disposed of properly, sediment from upland erosion, contaminants from road surface runoff and boats (sewage, bottom paint, oil), sunscreen, thermal pollution (WAPA discharge of RO effluents), pesticides, larger oil spills/leakage from tankers, oil leakage from marine gas stations, etc.
Much of the land-based pollution in the VI can be lumped into one of two categories: Point Source pollution, where the pollution comes from a known source, and Non-Point Source, where pollution originates from an unspecified source and accumulates through movement of stormwater. While great efforts have been put into reducing point sources (an exception being perhaps the dumpster sites in the USVI), land based sources of pollution are difficult to identify and control. Nonpoint source pollution results from rain water flowing over and through the ground, picking up pollutants (soil, oil, grease, bacteria, pathogens, heavy metals, nutrients, pesticides and other contaminants), carrying them away and depositing them into guts, wetlands, salt ponds, beaches, coastal waters and groundwater. Runoff is a problem for any wildlife that relies on water including frogs, birds (especially waterbirds), bats, and gut fauna (fish, shrimp). Although all habitats are affected by pollution, marine habitats are disproportionately affected simply because they are downstream. Every Virgin Islander is familiar with the sediment plumes in the ocean during torrential rains and the warnings to not swim in the ocean after rains due to contamination from pollutants washing into the water. Coral infection rates increase in correlation with rainfall events that carry stormwater with high sediment loads
The effects of pesticides on vital pollinators such as bees has been well documented (Desneaux 2007, Henry et al. 2012). The 2025 SWAP update is the first to include insects and it is clear that more research on population and distribution of the invertebrates in the VI is needed to assess the impact of pollutants on them. Wildlife such as birds, bats, frogs, and lizards that consume insects are also likely to be affected by pesticides. Bioaccumulation (the accumulation of a substance, such as pesticide in an organism) and biomagnification (the tendency of a pollutant to concentrate as it moves from one trophic level to the next) have major impacts on organisms higher in the food chain, including humans.
Fibropapillomatosis (FP), a herpes virus that causes tumors in seas turtles, has increased markedly in the USVI, especially in the last ten years. Green sea turtles are the most vulnerable. Environmental factors, including polluted waters and increased ocean temperatures, have been linked to FP outbreaks and may be contributing to the increase in the USVI.
Pollutants can render organisms, such as coral, more susceptible to disease. Studies on coral found that even a moderate increase in nutrients (such as from fertilizer) causes a significant increase in severity of coral disease (Bruno et al. 2003). A study in the northern VI found that nearshore corals were more susceptible to impairment, either through disease or mortality, than coral farther from shore. Sedimentation is believed to be one of the primary drivers of the nearshore coral degradation (Smith et al. 2012).
DFW participated in dragonfly sampling in 2023 that gave us some good news on one environmental issue: heavy metals. Dragonfly larva or "nymphs" are being collected across the USVI in collaboration with NPS, USGS in a national project to use dragonflies as bioindicator species for our freshwater ecosystems. Dragonfly nymphs are being tested for the presence of heavy metals such as mercury to inform agencies of possible sources of pollution in our freshwater ecosystems and in our National Parks. Aquatic insects, such as dragonfly nymphs, have been used as bioindicators for freshwater ecosystems since the 1970s in the continental US and so DPNR DFW decided to learn more about how the use of aquatic insects can be used as part of biomonitoring projects for freshwater habitats in the USVI. This helps us have information for our freshwater ecosystems to help protect the habitats for freshwater fauna such as the freshwater American Eel. All sites tested at Reef Bay Ghut, Lameshur Bay Ghut, Fish Bay Ghut, Carambola Golf Course Pond, Caledonia Ghut had no detectable or low-level concentrations of heavy metals tested. Here is an infographic from the NPS: infographic.
Bioindicators are living organisms such as plants, planktons, animals, and microbes, which are utilized to screen the health of the natural ecosystem in the environment. They are used for assessing environmental health and biogeographic changes taking place in the environment. Key pollutants of concern include nitrogen and phosphorus from runoff, pesticide drift into wetlands, and plastic / microplastic accumulation on shorelines. In urban fringe zones, runoff from impervious surfaces is intense; we aim to map pollutant hotspots and coordinate with planning agencies to implement green infrastructure buffers.