Top-down trophic shifts in Florida Keys patch reef marine protected areas

Special Protected Areas (SPAS) were established within the Florida Keys National Marine Sanctuary in 1997 to address a variety of management goals including coral reef resource protection and recovery. Within these areas all consumptive activities are prohibited. To evaluate whether SPA establishment has resulted in reef assemblage differences on inshore patch reefs, we quantified reef fish abundance and biomass, grazing intensity and benthic cover on abiotically similar protected and reference reefs. Transect surveys indicated that biomass and mean body lengths for several common predatory fish species were significantly greater within SPAS. Size classes of herbivorous fish also varied with protection; adult herbivorous fish were significantly more abundant, while juveniles were significantly less abundant within SPAS. Grazing intensity and benthic cover were site-specific and did not vary consistently with protection, suggesting that SPA establishment has not immediately (within 10 yr) driven observable indirect effects on the benthos.