We studied the coastal waters of southwest Puerto Rico to find out what kind and how much pollution (chemical contaminants) are in sediments and corals (Porites astreoides) and how that pollution affects the health of the coral reef. For the most part, concentrations of the pollutants analyzed were similar to what we have seen in other areas of the Caribbean. However, we found that the presence of certain types of pollutants was associated with a reduced number of reef-building coral species.
Why We Care
Pollution from urban areas, agriculture, and industry (land-based sources of pollution), along with marine-based activities (boating and shipping) are believed to be a significant factor in the degradation of coral reefs worldwide. Although pollution is frequently cited as reducing coral reef health, the amount of pollutants present in coral reefs is not well known, and typically even less is known about the effects of the contaminants on coral health. Because of this, coral reef managers may be missing important and, in some cases, critical information needed to maintain or restore coral reefs.
What We Found
Overall, the amount of chemical contaminants present was fairly low, usually below established guidelines. However, levels of PCBs ( a class of pollutants associated with former industrial use) and the metals chromium and nickel were above the guidelines at two sites sampled in Guanica Bay, indicating that organisms living in the sediments at these sites were at risk of being affected. In addition, an initial modeling exercise involving PAHs (oil and fuel related pollutants), indicated that PAHs in the sediments of the study area appeared to reduce the number of reef building coral species (also called coral species richness); that is, higher sediment concentrations of PAHs were associated with a lower number of reef building coral species. Additional research is needed to find out possible reasons for this pattern.
What We Did
We analyzed sediments and coral tissues for approximately 120 organic (oil and fuel pollutants, and pesticides) and inorganic (metal) chemical contaminants from the study area in southwest Puerto Rico, stretching roughly 20 km from Guanica Bay west past the town of La Parguera. The results of this study are contained in An Assessment of Chemical Contaminants in the Marine Sediments of Southwest Puerto Rico, and Chemical Contaminants in the Coral Porites astreoides from Southwest Puerto Rico.
The assessment in southwest Puerto Rico is complete. The work has influenced a second project, the Guanica Watershed Restoration Project. As part of this project, additional studies of chemical contamination within Guanica Bay and in the surrounding reefs outside the Bay are occurring.