New approaches to Mediterranean fluvial communities

Resum

The organization of fluvial benthic communities in the Iberian Mediterranean system shows a series of factors which differ in part from present models suggested in the current literature. The effects of disturbances can be observed in models including the gradient of organization (WARD & STANFORD, 1 983; VANNOTE et al. , 1 980; SABATER et al, . in press) in the major and permanent northwest basins, but not in temporary systems. Temporality does usual1y not represent a handicap as far as the organization of the algae communities and the macroinvertebrates communities is concemed,: equivalent diversities have been observed in temporary and permanent systems. But a latitudinal gradient is observed among the temporary systems, with an increment to the south of the diversity. Mediterranean fluvial systems have integrated floods as periodical perturbations in the dynamics of benthic communities, which have a high resistance to flood-related disturbance and a high subsequent resilience.