Benthic habitats, fish assemblages, and resource protection in Caribbean marine sanctuaries
Jeffrey, Christopher Francis Gabriel
MetadataShow full item record
Reef fishes and benthic habitats of the Florida Keys National Marine Sanctuary (FKNMS) were studied to examine spatial patterns in fish occurrence, effectiveness of volunteers in assessing fish species richness, spatial patterns in habitat occurrence, and the influence of habitats on reef fishes. Distinct regional patterns in fish composition were observed, with unique assemblages occurring in the Upper Keys, Middle, and Lower Keys, and Dry Tortugas. Mean species richness was higher in the Upper and Lower Keys than in the Middle Keys or Dry Tortugas. Three factors (diver, location, and dive time) explained 95% of the variation in mean fish species richness. Divers and dive time explained 70-94% and 41-74% of the variation in richness at Molasses Reef and in the FKNMS. Inexperienced volunteers detected greater among-site differences in richness but provided more variable and probably less reliable data than experienced volunteers. Survey location explained 32-57% of the variation in richness but only after the effects of diver and dive time were reduced by random selection of surveys. Habitat types varied among subregions and between protected and unprotected areas of the FKNMS. Seagrass habitats dominated the Upper and Lower Keys, whereas hardbottom habitats dominated the Dry Tortugas and Middle Keys. The Dry Tortugas had higher mean habitat richness and evenness than the Upper, Middle, and Lower Keys. Protected areas had greater habitat evenness but lower habitat richness than unprotected areas. Significant relationships existed between fishes and habitats. Assemblage trophic structure was most affected by habitat composition and abundance. Occurrence of generalized carnivores was negatively correlated, whereas occurrences of piscivores and herbivores were positively correlated with habitat richness and evenness. Occurrences of fishes, e.g., mahogany snapper, longfin damselfish, epinepheline and mycteropercine groupers, and small pelagic species were influenced by abundance of seagrass and hardbottom habitats but varied in the direction of the relationship, with some being positive and others negative. When coupled with geographic information systems based on accurate environmental maps, species-occurrence data from effective volunteer-monitoring programs could help identify important linkages between ecosystem components that are crucial to the successful implementation and management of marine protected areas.