New perspectives for ecological flow determination in semi-arid regions: a preliminary approach

摘要

Streams in semi-arid regions, such as the south of Portugal, have highly seasonal flow regimes with a marked pattern of low or zero flow during summer and early autumn. As a result, throughout these months, most rivers have long dry reaches with occasional pools. The biotic communities have evolved specific adaptive strategies to face those alternating lotic-lentic conditions, but when the dry season becomes longer and/or more extreme, the environmental stress can be lethal for important groups of the biota.