Ecology of the macroinvertebrate communities in Mediterranean rivers at different scales and organization levels

Abstract

The main objective of this work has been to determine the structure of the macroinvertebrate communities in mediterranean rivers at different scales, organization and taxonomical levels. To achieve that, an appropriated sampling methodology for macroinvertebrate studies has been developed. Physical and chemical data and riparian and habitat characteristics have been also recorded in each sampling site. <br/><br/>At regional scale it has been studied the macroinvertebrate composition at family level in all mediterranean regions around the world: California, Mediterranean Basin, Chile, South Africa and South and South-western Australia. Convergences and divergences between regions have been established pointing out the influence of the historical and ecological factors. <br/><br/>At local scale the effect of the temporality (differences between permanent and temporary rivers) and habitat (differences between riffles and pools) over the macroinvertebrate community in mediterranean rivers of the world have been studied. The results demonstrate a degree the convergence in the responses to temporality and habitat, being this last factor more convergent that the former. Moreover, the effects of the temporality over habitat and vice versa have been analyzed, indicating that both are strong correlated: temporality change the habitat and habitat influence over the temporality of the reach. Both aspects have an important effect over the macroinvertebrate community at different levels of observations from richness or composition to biological traits. <br/><br/>Moreover, at a lower taxonomical level, caddisfly community from Spanish mediterranean rivers has been studied. A total of 91 species have been identified using larvae, pupae and adults. The distribution patters displayed by these organisms indicate that historical factors may be important for some species, although most of them have a distribution limited by ecological variables. In that sense, ecological factors associated to large (basin) or small (reach or habitat) scale are important in the caddisfly distribution. Finally, because the importance of the caddisfly as bioindicators, optimums and tolerances to several chemical variables have been obtained for all species. Moreover, a study of the effect of the pollution over the fluctuating asymmetry of Hydropscyhe exocellata populations have demonstrated that at this level, there is a strong relatio.