S-INFINITY - A NEW METHOD FOR CALCULATING MACROBENTHIC SPECIES RICHNESS

A simple mathematical method is proposed to calculate the total number of macrobenthic species present within a community when quadrat sampling is involved. The total number of species (S-infinity) is calculated by extrapolation as the point beyond which no further increase in the cumulative number of species is expected by additional sampling effort. To this end the cumulative number of species in k samples is plotted against the cumulative number of species in k + 1 samples. The equation of the resulting line is solved for y = x, thus obtaining the intercept point with the bisector of the angle between the rand y axes. Different benthic data sets were used for testing the method, all of which gave satisfactory results. The method may be used in biodiversity and biogeography studies to compare species richness between different areas and in ecological studies to define the minimum sampling area.