A piecewise regression approach for determining biologically relevant hydraulic thresholds for the protection of fish at river infrastructure
Barotrauma injury can occur when fish are exposed to rapid decompression during downstream passage through river infrastructure. A piecewise regression approach was used to objectively quantify barotrauma injury thresholds in two physoclistous species (Murray cod Maccullochella peelii and silver perch Bidyanus bidyanus) following simulated infrastructure passage in barometric chambers. The probability of injuries such as swim bladder rupture; exophthalmia; and haemorrhage and emphysema in various organs increased as the ratio between the lowest exposure pressure and the acclimation pressure (ratio of pressure change RPCE/A) fell. The relationship was typically non-linear and piecewise regression was able to quantify thresholds in RPCE/A that once exceeded resulted in a substantial increase in barotrauma injury. Thresholds differed among injury types and between species but by applying a multi-species precautionary principle, the maintenance of exposure pressures at river infrastructure above 70% of acclimation pressure (RPCE/A of 0.7) should sufficiently protect downstream migrating juveniles of these two physoclistous species. These findings have important implications for determining the risk posed by current infrastructures and informing the design and operation of new ones.
Revised: September 26, 2016 |
Published: May 13, 2016
Boys C.A., W. Robinson, B. Miller, B.D. Pflugrath, L.J. Baumgartner, A. Navarro, and R.S. Brown, et al. 2016.A piecewise regression approach for determining biologically relevant hydraulic thresholds for the protection of fish at river infrastructure.Journal of Fish Biology 88, no. 5:1677–1692.PNNL-SA-109599.doi:10.1111/jfb.12910