The effects of simulated hydropower turbine rapid decompression on two Neotropical fish species

J R Kerr; A L F Castro; N O Melo; J A Daniels; A Holgate; L A Dolman; L G M Silva; P S Kemp

doi:10.1016/j.scitotenv.2023.166770

The effects of simulated hydropower turbine rapid decompression on two Neotropical fish species

Sci Total Environ. 2023 Dec 10:903:166770. doi: 10.1016/j.scitotenv.2023.166770. Epub 2023 Sep 1.

Authors

J R Kerr¹, A L F Castro², N O Melo², J A Daniels³, A Holgate³, L A Dolman³, L G M Silva⁴, P S Kemp³

Affiliations

¹ International Centre for Ecohydraulics Research, Faculty of Engineering and Physical Sciences, University of Southampton, Boldrewood Campus, Southampton SO16 7QF, United Kingdom. Electronic address: j.kerr@soton.ac.uk.
² Molecular Ecology & Ichthyology Lab, Department of Natural Sciences (DCNAT), Universidade Federal de São João del-Rei (UFSJ), Praça Frei Orlando 170, 36307-352 São João del-Rei, MG, Brazil.
³ International Centre for Ecohydraulics Research, Faculty of Engineering and Physical Sciences, University of Southampton, Boldrewood Campus, Southampton SO16 7QF, United Kingdom.
⁴ Stocker Lab, Institute for Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH-Zurich, Zurich 8046, Switzerland.

PMID: 37660813
DOI: 10.1016/j.scitotenv.2023.166770

Abstract

Barotrauma is a major cause of injury and mortality of fish as they pass through hydropower turbines. Current understanding of hydropower related barotrauma is biased towards northern temperate and southern subtropical species with single chambered swim bladders, specifically North American and Australian species, respectively. Today, unprecedented hydropower development is taking place in Neotropical regions where many species have complex multi-chambered swim bladder architecture. This study investigated barotrauma in two dual-chambered physostomous Neotropical fish (pacu, Piaractus mesopotamicus, and piracanjuba, Brycon orbignyanus) exposed to rapid (< 1 s) decompression at different Ratios of Pressure Change (RPC), using a hypo-hyperbaric chamber. The incidence and intensity (percentage surface area of organ affected) of injury and physiological and behavioural response (hereafter just response) of each species immediately after decompression was assessed. Twenty-two injury types (e.g. gill haemorrhage and exophthalmia) and eight response categories (e.g. rising to the surface and loss of orientation) were identified and the influence of: 1) species, 2) RPC, and 3) swim bladder rupture on each was quantified. There was considerable interspecific difference with emboli type injuries occurring more frequently in piracanjuba, but injury intensity tending to be higher in pacu. Both swim bladder chambers tended to rupture in piracanjuba but only the anterior chamber in pacu. RPC was positively correlated with response, incidence and intensity of several injury types for both species with some injuries occurring at very low RPC (e.g. 50 % probability of swim bladder rupture at 2.2 and 1.75 for piracanjuba and pacu, respectively). Multiple responses (e.g. loss of orientation) and injuries (e.g. eye haemorrhage) were correlated with swim bladder rupture suggesting gas venting into the body cavity likely causes secondary injury. When directly comparing our results with those available in the published literature, both pacu and piracanjuba appear to be more susceptible to barotrauma than previously studied subtropical and temperate species.

Keywords: Barotrauma; Fish behaviour; Hypo-hyperbaric chamber; Ratio of pressure change; Swim bladder rupture.