ABC Method and Biomass Size Spectra: What About Macrozoobenthic Biomass on Hard Substrata?

In order to study their usefulness for ecological monitoring, the Abundance–Biomass comparison (ABC method) and Biomass Size Spectra (BSS) have been applied to hard substrata macrozoobenthic communities of a marine bay affected by river pollution. Both methods reveal several features related to the stress effects of suspended solids, such as the substantial development of suspension-feeder beds towards the inner parts of the bay (more polluted) or the resulting dominance of macrofauna over macroflora at those sites. The animal dominance on stressed rocky shores is higher in terms of biomass than in terms of abundance. By means of the synthetic parameters W(ABC method) and m(slope of the Normalized Biomass Size Spectra, NBSS), these two methods are correlated with other parameters of community diversity and biomass. In addition, W and m are positively correlated except for the upper intertidal zone. However, it has not been possible to interpret the results following the criteria for soft substrata or for pelagic systems, where the methods were developed. The inclusion of algae and a different treatment of suspension-feeders are suggested as ways of improving the future application of these graphical/distributional techniques on hard substrata.