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It’s a catfish! Novel approaches are needed to study the effects of rapid decompression on benthic species

Luiz G. M. Silva, Bernardo V. Beirão, Ricardo C. Falcão, Andrey L. F. de Castro, Edson W. Dias
Marine & freshwater research 2018 v.69 no.12 pp. 1922-1933
Pimelodus, Salmonidae, acclimation, benthic organisms, catfish, dams (hydrology), dose response, nekton, Brazil
Barotrauma as a result of rapid decompression has been recorded as the most common injury among fish captured in the tailrace of hydropower dams in Brazil, with catfishes representing the majority of them. Nevertheless, studies investigating barotrauma on catfish are scarce, with the majority determining dose–response curves and thresholds of pressure changes for nektonic species, such as salmonids. Experiments conducted with Pimelodus pictus showed that the current hypo-hyperbaric chambers used to study barotrauma in nektonic species can have limitations when applied to benthic groups. The negative buoyancy showed by the catfish prevented the definition of the acclimation pressure of the fish before exposure to decompression and, therefore, the method had to be adapted to allow the calculation of the ratio of pressure change (RPC). The adaptation involved anaesthetising the fish, which added a potential bias to the experiments. Therefore, new approaches deemed to be needed to complement barotrauma studies with benthic fish. We aimed to discuss the limitations observed for studies with benthic species and present potential methods to overcome them. The diversification of approaches for barotrauma studies with benthic species is critical to provide information for the development of mitigation and new turbine designs that would improve protection of this group.