Hernandez-Delgado, E. A., Gonzalez-Ramos, C. M., Medina-Muniz, J. L., Montanez-Acuna, A. A., Otano-Cruz, A., Rosado-Matias, B. J., Cabrera-Beauchamp, G.
Widespread impacts of land-based source pollution on Southwestern Puerto Rican coral reefs. Appendix A9 to Cabo Rojo Community Watershed Action Plan for Water Quality and Coral Reefs
San Juan, Puerto Rico
Sociedad Ambiente Marino and University of Puerto Rico/CATEC
Type Period Note:
"Local coral reef ecosystems across the southwestern Puerto Rico shelf still represent a critical natural resource with invaluable socio-economic significance. However, they were showing unequivocal signs of decline mostly as a result of chronic land-based source pollution (LBSP) impacts. This study showed important evidence suggesting there were signs of a LBSP gradient across the western Puerto Rico shelf and that chronic water quality decline has significantly affected the face of coral reef benthic communities, coral recruit assemblages, and have indirectly affected reef fish communities. A snapshot view of water quality across the shelf showed that particularly turbidity and phosphate (PO4) and ammonium (NH4+) concentrations increased along inshore sites, while dissolved oxygen concentration declined along inshore waters. PO4 concentrations resulted nearly 11 times above the recommended concentration for healthy coral reefs across inshore sites, almost 8 times across mid-shelf sites, and about 3 times across outer shelf sites. Observed NH4+ concentrations across inshore sites exceeded 981 times the recommended concentration for healthy coral reefs. Concentrations also exceeded the recommended limits 590 times across mid-shelf sites, and 155 times across outer shelf sites. Chlorophyll-a concentration was up 4 to 7 times higher than recommended limits for healthy coral reefs across inshore sites, 3 to 6 times across mid-shelf sites, and 3 to 6 times across outer shelf sites. Coral reef benthic community structure, coral recruit assemblages and fish community structure showed significant differences across the observed LBSP gradient. Coral species richness, Hn, Jn and percent living cover increased with increasing distance from the shore. Also, coral recruit abundance and the presence of important reef-building species increased with increasing distance. Overall fish species richness, abundance, biomass, and the abundance and biomass of total carnivores, piscivores, omnivores, and of many fishery-targeted species (subfamily Epinephelinae, family Lutjanidae) and indicator species (Chaetodontidae, Pomacentridae) increased with increasing distance from the shore. Nonetheless, inshore coral reef ecosystems still supported critical large populations of juvenile and semi-adult stages of parrotfishes (Scaridae) and other fish taxa. This suggests the critical importance of protecting and restoring inshore and mid-shelf coral reefs. Multiple recommendations are discussed to address LBSP impacts across the shelf, to implement best management practices (BMPs) to reduce impacts, to monitor its impacts on coastal ecosystems, and to rehabilitate reef ecological functions of inshore and mid-shelf coral reefs."
Funded by NOAA CRCP grant NA10NOS4630131 and NFWF FY2013 Project ID 38943, Project Title: Developing a Watershed Action Plan for Cabo Rojo, Puerto Rico