Estudo comparativo de métodos de amostragem de comunidades de Costão

Abstract

This study compares three sampling methodologies of rocky shore communities: visual estimation, point intercept quadrats and destructive sampling. Visual estimation was performed in two sizes of sampling device and, point intercept quadrats was done with different numbers of marked dots. The sampling took place on the rocky shore of Forno beach, Buzios, RJ, in two different algae belts; one whose the landscape is characterized by Amphiroa sp., the other, Sargassum furcatum was the most conspicuous species. The data were analyzed by ANOVA and Kruskal-Wallis tests. Number of species, total percent cover, diversity and evenness indices were the variables used. The results shown that in general the methods compared were not statistically different one from the other in this community. There were significative differences between the methods when comparison was made between non-destructive and destructive sampling. However, smaller areas of sampling devices and fewer intercept points decreased the sampling power in respect of sampling species richness. All of the methods studied were considered similar in concern of total cover index and of diversity and evenness indices, with some exceptions. Present data are useful only for rocky communities with similar profiles. The choice of method must be made in regard of each situation.