Comparative study of the estimated sample size for benthic intertidal species and communities.

The objective of this study was to determine the minimum sample size for studies of community structure and/or dominant species at different heights of a rocky intertidal zone at Rio de Janeiro. Community structure indicators suggested a variation in the minimum surface of 100 to 800 cm², with a minimum of 2 to 8 profiles and at least 20 to 80 quadrant sampling points, depending on the height. Indicators of species abundance suggest 100 cm² for Hypnea musciformis and 400 cm² for Ulva fasciata, Phragmatopoma lapidosa Kinberg, (1867) and Gymnogongrus griffthsiae at lower heights; 200 cm² for Chthamalus spp. at intermediate heights; and 800 cm² for Littorina ziczac at the greatest height. In general, seven to eight profiles and 10 to 20 sampling points were used. Different sample sizes were related to the abundance and spatial distributions of individual species, which varied at each intertidal height according to the degree of environmental stress. [ABSTRACT FROM AUTHOR]