Mapping Prevalence and Incidence of Coral Disease in reef-building corals at two Natural Reserves of the Southwest Puerto Rico
Mapping Prevalence and Incidence of Coral Disease in reef-building corals at two Natural Reserves of the Southwest Puerto Rico
Abstract:
Coral diseases seems to be the main cause of coral reef decline in the Caribbean. Before the bleaching event of 2005, coral reefs in Puerto Rico were dominated by the reef-building taxa: Orbicella annularis, Porites astreoides, Montastrea cavernosa, Agaricia agaracites and Colpophyllia natans. After the event, live-coral cover significantly declined and more than 90% of the scleractinian corals in the U.S. Virgin Islands and Puerto Rico showed signals of thermal stressors. The prevalence of coral diseases in five reef-building coral (Orbicella annularis, Orbicella franksi, Orbicella faveolata, Porites porites and Pseudiploria strigosa) species was assessed by tagging, photographing, and mapping all diseased and healthy colonies within 10 permanent 40m2 band transects at each inshore and mid-shelf reefs of Belvedere and Punta Guaniquilla Natural Reserves using a random stratified sampling method. Maximum and perpendicular diameter was used to assess coral size using Coral Point Count with Excel Extension. Corals were classified into three size class populations (class I: 0-50cm, class II: 50-100cm and class III: >100 cm). Data was used to develop a GIS-based map containing coral species, size and disease presence. Preliminary results of the inshore area showed a higher disease prevalence in Belvedere natural reserve and for P. strigosa (17.1%) and O. annularis (9.3%). Frequency distribution analysis showed a dominance of O. faveolata at Punta Guaniquilla and Belvedere (127 and 88 individuals respectively). Size class I dominates the distribution of each species within the natural reserves with a higher disease prevalence. Future work include continue prevalence surveys of the outer reef shelf on both natural reserves, monitoring and GIS-based mapping of incidence and resilience through time. This study will help in the assessment of the status of the coral reef of the southwest insular platform.