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

Abstract

ABSTRACT: Special Protected Areas (SPAs) were established within the Florida Keys NationalMarine Sanctuary in 1997 to address a variety of management goals including coral reef resourceprotection and recovery. Within these areas all consumptive activities are prohibited. To evaluatewhether SPA establishment has resulted in reef assemblage differences on inshore patch reefs, wequantified reef fish abundance and biomass, grazing intensity and benthic cover on abiotically simi-lar protected and reference reefs. Transect surveys indicated that biomass and mean body lengths forseveral common predatory fish species were significantly greater within SPAs. Size classes of herbiv-orous fish also varied with protection; adult herbivorous fish were significantly more abundant, whilejuveniles were significantly less abundant within SPAs. Grazing intensity and benthic cover weresite-specific and did not vary consistently with protection, suggesting that SPA establishment has notimmediately (within 10 yr) driven observable indirect effects on the benthos.KEY WORDS: Marine reserve · Coral reef · Florida Keys · Trophic cascade · Parrotfish · Herbivory