Challenges and Opportunities for the Assessment of the Ecological Status in Temporary Rivers

Temporary rivers (TRs) are stream ecosystems in which the effects of anthropogenic disturbances are mixed with the effects of the natural disturbance imposed by flow intermittence. Despite the advances in TRs research, many gaps persist that limit the development of appropriate methodologies for the assessment of the ecological status. In this review, we identify the current challenges for the assessment of the ecological status of TRs and analyze the existing opportunities to address these challenges. These challenges focus on: the differentiation between natural and hydrologically impacted TRs, the differentiation between natural and anthropogenic disturbances, the development of biological indices for disconnected pools and dry riverbeds, the adaptation of hydrogeomorphological indices, and the application of the metacommunity theory in TRs. The opportunities are related to: the use of molecular tools, the existence of alternative indices to the traditional ones, the availability of data to be able to do modeling, and the social implication in the assessment of the hydrological and ecological status. The review focuses mainly on the scientific and management knowledge accumulated since the implementation of the Water Framework Directive in Spain but gathers experiences from TRs around the world to guide conservation and management actions in these unique ecosystems highly threatened by global change.