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Coral reef condition and benthic sedimentation threat in four regions of south Puerto Rico
Citation:
Oliver, L., W. Fisher, J. Awkerman, J. campbell, P. Harris, Becky Hemmer, C. Lobue, M. Parsons, Debbie Santavy, AND S. Vickery. Coral reef condition and benthic sedimentation threat in four regions of south Puerto Rico. Presented at CERF 2013, San Diego, CA, November 03 - 07, 2013.
Impact/Purpose:
Describe relationships between indicators of reef condition and modeled sedimentation threat in south Puerto Rico.
Description:
Scleractinian corals, gorgonian octocorals, sponges and fishes were assessed near the cities of LaParguera, Guánica, Guayanilla, and Jobos along the southern coast of Puerto Rico in November – December 2010. Survey sites were targeted near areas with varying benthic sedimentation identified using the Summit to Sea sedimentation model, which uses spatial watershed delineation, soil k-factors (indicating erodibility of the soil type), slope, precipitation, and land cover type to estimate sediment delivery potential at river mouths or other “pour points”. Number and condition of stony corals, gorgonians, sponges, fish and macroinvertebrates were measured, and indicators of organism abundance and condition were analyzed to evaluate whether reef indicators showed significant relationships with modeled benthic sediment threat (BT). Across regions, average BT was highest for Guayanilla stations, with averages for Guánica, Jobos and LaParguera stations 59, 23, and 18% of Guayanilla. Along with highest BT, Guayanilla stations exhibited the lowest average number of stony coral taxa, smallest colony size, and lowest colony density. Fish, gorgonian and sponge indicators at Guayanilla stations were intermediate among the regions, and invertebrate abundance including Diadema highest. Within regions, indicator correlations with BT were highly variable. Average percent live coral showed a negative correlation with BT for LaParguera stations but a positive correlation with BT in Guayanilla and Jobos. The average density of gorgonians negatively correlated with BT for LaParguera and Jobos, but positively correlated with BT at Guayanilla. Contrasting regional relationships could be influenced by differences in coastal land uses and also by sediment transport dynamics that are not captured in the watershed threat model. The sedimentation threat model may be a better predictor of stress to coral reefs across regional scales compared to within-reef scales.