The Effect of Floods on Aquatic Invertebrate Communities

摘要

Almost all rivers experience increases in discharge, although whether this results in a flood depends on the size of the increase, channel morphology and hydrology. High flows have many effects on aquatic invertebrates both directly and indirectly through changes to habitat. Shear stress on the stream bed increases, removing organisms or forcing them to seek refuge among substrates or in the drift. Substrates can be moved, scouring invertebrates and their periphyton food source. Numerous studies haveshown that floods reduce invertebrate abundances and diversity, although the threshold flows at which this occurs still remain contentious. However, recovery from most floods is relatively rapid and invertebrates persist even in very flood-prone streams. This is a result of many taxa having morphological, behavioural and life-history strategies to cope with the effects of floods. Although we have been aware of the community-level effects of floods on aquatic invertebrates for decades, it still remainsunclear how many individual taxa respond, what motivates that response and what drives the recovery process. Understanding these patterns is key to our ability to manage flow variability to maintain ecosystem integrity in the face of increasing pressureto remove floods from a river's hydrology regime.