Fish traits as an alternative tool for the assessment of impacted rivers.

The current scenario of worldwide exponential increase in river impoundment (dams) and the compounded effects of climate change are among the most important threats to freshwater ecosystems. The sharp decline in the biodiversity of impacted rivers demands the enhancement of available tools for biomonitoring and improved approaches for informing environmental decision-making. Here, we demonstrate examples of how fish trait analyses could be used to assess and predict the response of fish communities to damming and how this approach has potential advantages over traditionally used methods by linking suites of traits to stressor effects through plausible cause and effect mechanisms. Using a trait-based analysis is advantageous as it transcends taxonomy, can be applied across broad spatial scales and be easily integrated into current assessment programs. Therefore, it is a promising tool for biomonitoring in freshwater ecosystems. However, some challenges remain in the application of this approach namely the lack of universality of trait-habitat links; the availability, consistency, and applicability of existing trait data; low discriminatory power and poor mechanistic understanding. Nonetheless adaptive river management can benefit from this approach by sustainably operating dams in the light of knowledge on how the functional structure of fish communities are altered, thus enabling essential habitats for fish to be maintained. [ABSTRACT FROM AUTHOR]