1 - In order to use benthic macrophyte communities as bioindicators of transitional and coastal waters an understanding of main community organization mechanisms along water quality gradients is necessary. 2 - Four different approaches are presented briefly: (a) scale-based variation of biotic indices in lagoon macrophyte communities, (b) multivariate analysis of community at species and functional group levels, (c) scale-based variation of body size descriptors of angiosperms, (d) eco-toxicological tests of mechanistic stressor-response relationships. 3 - Since growth of benthic macrophytes seems to be related to species’ ability to exploit the most abundant resources they can be successfully used as bioindicators of eutrophication in transitional and coastal waters.