Abstract

The mapping of benthic habitats and corresponding fish fauna is essential for understanding the role of habitat in controlling the spatial distribution of fish abundance, diversity and production. Any approach to mapping must first standardize habitat definitions and classification, as well as a data collection methodology. Visual transects are a standard tool for quantifying fish abundance and habitat characteristics. Yet, for purposes of mapping and analysis these data must be scaled up to their relative areas. We report on a methodology using stratified sampling and Geogmphic Information System (GIS) teChnology to convert transect data into larger-scale habitat maps, illustrating the procedure with data from La Parguera. Puerto Rico. Sampling strata are determined using two criteria. The first is Lindeman's cross-shelf habitat (CSH) classification system adapted to the local insular shelf; the main determinants are position in the cross-shelf directiOD and depth. The second criterion is based on a visual nspection of the array of different habitat mosaics (l00's m2) present within any CSH stratum (e.g., grassbed, sand/algae plain, gorgonian/coral field). Representative transects, replicated where possible, are placed in the different habitat-mosaics, and associated fishes and habitats are quantified. Areas within each habitat-mosaic stratum can be determined using a variety of approaches such as field mapping with Global Positioning System (GPS) coordinates, or remote sensing using aerial photography or side-scan sonar. Use of GIS technology allows transect data to be overlain on the habitat-mosaic and CSH strata and facilitates further analyses such as calculatiOn of total abundances and estimation of both fish and habitat diversity.

PDF Preview