title: How low can they go when going with the flow? Tolerance of egg and larval fishes to rapid decompression.
abstract: Egg and larval fish that drift downstream are likely to encounter river infrastructure and consequently rapid decompression, which may result in significant injury. Pressure-related injury (or barotrauma) has been shown in juvenile fishes when pressure falls sufficiently below that at which the fish has acclimated. There is a presumption that eggs and larvae may be at least as, if not more, susceptible to barotrauma injury because they are far less-developed and more fragile than juveniles, but studies to date report inconsistent results and none have considered the relationship between pressure change and barotrauma over a sufficiently broad range of pressure changes to enable tolerances to be properly determined. To address this, we exposed eggs and larvae of three physoclistic species to rapid decompression in a barometric chamber over a broad range of discrete pressure changes. Eggs, but not larvae, were unaffected by all levels of decompression tested. At exposure pressures below ∼40 kPa, or ∼40% of surface pressure, swim bladder deflation occurred in all species and internal haemorrhage was observed in one species. None of these injuries killed the fish within 24 h, but subsequent mortality cannot be excluded. Consequently, if larval drift is expected where river infrastructure is present, adopting design or operational features which maintain exposure pressures at 40% or more of the pressure to which drifting larvae are acclimated may afford greater protection for resident fishes.
authors.affiliation: New South Wales Department of Primary Industries, Port Stephens Fisheries Institute, Taylors Beach Road, Taylors Beach, New South Wales 2316, Australia craig.boys@dpi.nsw.gov.au.
authors.forename: Craig A
authors.initials: CA
authors.lastname: Boys
authors.affiliation: Institute of Land, Water and Society, Charles Sturt University, Elizabeth Mitchell Drive Thurgoona, New South Wales 2640, Australia New South Wales Department of Primary Industries, Narrandera Fisheries Centre, 64 Buckingbong Road Narrandera, New South Wales 2700, Australia.
authors.forename: Wayne
authors.initials: W
authors.lastname: Robinson
authors.affiliation: Water Research Laboratory, University of New South Wales, 110 King Street Manly Vale, New South Wales 2093, Australia.
authors.forename: Brett
authors.initials: B
authors.lastname: Miller
authors.affiliation: New South Wales Department of Primary Industries, Port Stephens Fisheries Institute, Taylors Beach Road, Taylors Beach, New South Wales 2316, Australia.
authors.forename: Brett
authors.initials: B
authors.lastname: Pflugrath
authors.affiliation: Institute of Land, Water and Society, Charles Sturt University, Elizabeth Mitchell Drive Thurgoona, New South Wales 2640, Australia New South Wales Department of Primary Industries, Narrandera Fisheries Centre, 64 Buckingbong Road Narrandera, New South Wales 2700, Australia.
authors.forename: Lee J
authors.initials: LJ
authors.lastname: Baumgartner
authors.affiliation: Institute of Land, Water and Society, Charles Sturt University, Elizabeth Mitchell Drive Thurgoona, New South Wales 2640, Australia.
authors.forename: Anna
authors.initials: A
authors.lastname: Navarro
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA 99354, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Brown
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA 99354, USA.
authors.forename: Zhiqun
authors.initials: Z
authors.lastname: Deng
keywords: Barotrauma; Hydropower; Larval drift; Murray-Darling basin; Physoclistous; Piecewise regression