Anthropogenic influence on sedimentation and hydrocarbon concentration by terrestrial run-off near a drain in Bonaire, Dutch Caribbean
The anthropogenic effect of terrestrial run-off on coral reef ecosystems is a topic of high concern to marine ecologists. In the Caribbean, coral cover is decreasing at an alarming rate, and phase shifts to an algae-dominated reef have been documented. Studies have shown a correlation between densely populated coastal communities and high levels of substances known to be detrimental to marine ecosystems. This study focuses on two contaminants common in waters affected by terrestrial run-off: fine sediment and UV reactive hydrocarbons. Fine sediment cannot be removed easily from the tissues of corals and can prevent corals from receiving enough light. UV reactive hydrocarbons can embed themselves in tissue membranes and cause oxidative damage upon exposure to UV light. The presence and effects of these contaminants were determined near a drain in Bonaire, Dutch Caribbean. The percent distribution of sediment grain sizes was determined at increasing distances from the drain. The results revealed that the percentage of fine sediment is highest close to the drain and decreases with increasing distance from it. The presence of UV reactive hydrocarbons was determined using bioassays of Artemia sp. The results of the bioassays suggest that run-off from the drain contains UV reactive hydrocarbons. The effect of these contaminants on the abundance of organisms in benthic communities was analyzed using endobenthos technique but results were inconclusive. This study determined the presence of fine sediment and UV reactive hydrocarbons due to a point source of terrestrial run-off.