THE SEASCAPE APPROACH TO CORAL ECOSYSTEM MAPPING: AN INTEGRAL COMPONENT OF UNDERSTANDING THE HABITAT UTILIZATION PATTERNS OF REEF FISH

摘要

Benthic maps provide the fundamental analytical framework to design reef-monitoring programs, organize spatial data, and to conduct spatially-explicit assessments of various components of the reef ecosystem. To meet the need for benthic maps, novel software that emphasizes simplicity but maintains capability in the mapping process was developed to delineate benthic features directly into a Geographic Information System. The software expedites mapping relative to more commonly used mapping techniques while maintaining excellent thematic and spatial accuracies. A hierarchical classification scheme was used in which the major bottom types were unconsolidated sediment, coral reef and hard bottom, and submerged vegetation. Mapping in the U.S. Virgin Islands covered 23.9 km~2 of unconsolidated sediment, 160.5 km~2 of submerged vegetation, and 298.7 km~2 of coral reef and hard bottom. Mapped features were also given a location attribute such as back reef or fore reef according to their position relative to the shoreline and lagoon-forming reefs. There were large differences in spatial extent among zones such as lagoon and back reef (22.9 km~2, 4.7% of the total area) and bank/shelf (433.9 km~2, 88% of the total area). Thematic accuracy of maps produced using the new approach was measured by comparing ground survey data to map attributes and was similar to the accuracy of maps produced with an analytical stereo plotter. Recent literature indicates that analysis of fish census data in concert with such benthic maps can be used to more clearly evaluate fish distributions relative to analysis of census data without a seascape framework.