An asymmetrical sampling design as a tool for sustainability assessment of human activities in coastal systems: a fish farming study case

摘要

The proposed use of an asymmetrical sampling design to evaluate the sustainability of human activities in coastal systems was tested on an aquaculture impact assessment. Two small fish farms located in a protected area were studied, one sited on an unvegetated soft bottom and the other on a seagrass meadow. Biotic and abiotic variables at sites of fish farms were compared with appropriate reference sites located at two different distances from the cages (300 m and 1000 m) through an asymmetrical sampling design. All the considered descriptors significantly differed between the sites under the cages and the reference sites in both seagrass and unvegetated habitats; by contrast, no significant differences were detected between the reference sites located at the two different distances from the cages, suggesting a spatially limited impact of the farms. The asymmetrical sampling design was able not only to detect an impact on benthic assemblages, but also to evaluate the spatial extent of this impact. The approach proposed in this study can be considered suitable to evaluate the sustainability of aquaculture farms and other human activities in marine coastal areas.