Effects of suboptimal temperatures on larval and juvenile development and otolith morphology in three freshwater fishes:

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Effects of suboptimal temperatures on larval and juvenile development and otolith morphology in three freshwater fishes: implications for cold water pollution in rivers Laura E. Michie & Jason D. Thiem & Jordan A. Facey & Craig A. Boys & David A. Crook & Simon M. Mitrovic

Received: 25 June 2020 / Accepted: 25 October 2020 # Springer Nature B.V. 2020

Abstract Temperature is a key determinant that governs fish survival, reproduction, growth and metabolism. In freshwater ecosystems, anthropogenic influences have resulted in acute and prolonged temperature changes which lead to lethal and sub-lethal impacts on the biota that occupy these environments. We assessed the effects of temperature on somatic and otolith growth and development of three species of native Australian freshwater fish (silver perch Bidyanus bidyanus, trout cod Maccullochella macquariensis and golden perch Macquaria ambigua) to simulate how thermal pollution from the release of unseasonably cold water from thermally stratified dams in Australian freshwater Supplementary Information The online version contains supplementary material available at https://doi.org/10.1007 /s10641-020-01041-z. L. E. Michie (*) : J. A. Facey : S. M. Mitrovic School of Life Sciences, University of Technology Sydney, PO Box 123, Broadway, New South Wales 2007, Australia e-mail: [email protected] J. D. Thiem NSW Department of Primary Industries, Narrandera Fisheries Centre, PO Box 182, Narrandera, New South Wales 2700, Australia C. A. Boys NSW Department of Primary Industries, Port Stephens Fisheries Centre, Taylors Beach Road, Taylors Beach, New South Wales 2316, Australia D. A. Crook Centre for Freshwater Ecosystems, La Trobe University, McCoy Street, Albury-Wodonga, Victoria 3690, Australia

ecosystems may impact fish at critical life-history stages. Fish (31 days post-hatch) were exposed to four temperature treatments (13, 16, 20, 24 °C) for 30 days. Low temperatures resulted in reduced somatic growth, with no growth observed in silver perch and golden perch held at 13 °C over 30 days. Somatic growth was highest at the upper temperature of 24 °C. Morphological assessment of fish size reiterated that low water temperatures resulted in reduced body size, particularly in terms of body width and head size. Low temperatures were associated with reduced otolith growth in all species, however a somatic-otolith size relationship was maintained for all species in measures of otolith weight, area, length and perimeter. The sub-lethal impacts observed in our study are likely to manifest at the population level through a reduced capacity of larvae and juveniles to avoid size-dependent predation, a narrower range of prey sources due to extended gape-limited feeding and, ultimately, poorer survival and recruitment. Keywords Fish . Freshwater . Growth . Otolith . Temperature . Thermal pollution

Introduction Temperature is an important regulator of the biological processes of aquatic organisms (Brett 1971). As ectotherms, fish depend on temperature as a determinant of metabolism