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Earhart ML, Blanchard TS, Morrison PR, Strowbridge N, Penman RJ, Brauner CJ, Schulte PM, Baker DW. Identification of upper thermal thresholds during development in the endangered Nechako white sturgeon with management implications for a regulated river. CONSERVATION PHYSIOLOGY 2023; 11:coad032. [PMID: 37228298 PMCID: PMC10205467 DOI: 10.1093/conphys/coad032] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/20/2023] [Accepted: 04/27/2023] [Indexed: 05/27/2023]
Abstract
Climate change-induced warming effects are already evident in river ecosystems, and projected increases in temperature will continue to amplify stress on fish communities. In addition, many rivers globally are impacted by dams, which have many negative effects on fishes by altering flow, blocking fish passage, and changing sediment composition. However, in some systems, dams present an opportunity to manage river temperature through regulated releases of cooler water. For example, there is a government mandate for Kenney dam operators in the Nechako river, British Columbia, Canada, to maintain river temperature <20°C in July and August to protect migrating sockeye salmon (Oncorhynchus nerka). However, there is another endangered fish species inhabiting the same river, Nechako white sturgeon (Acipenser transmontanus), and it is unclear if these current temperature regulations, or timing of the regulations, are suitable for spawning and developing sturgeon. In this study, we aimed to identify upper thermal thresholds in white sturgeon embryos and larvae to investigate if exposure to current river temperatures are playing a role in recruitment failure. We incubated embryos and yolk-sac larvae in three environmentally relevant temperatures (14, 18 and 21°C) throughout development to identify thermal thresholds across different levels of biological organization. Our results demonstrate upper thermal thresholds at 21°C across physiological measurements in embryo and yolk-sac larvae white sturgeon. Before hatch, both embryo survival and metabolic rate were reduced at 21°C. After hatch, sublethal consequences continued at 21°C because larval sturgeon had decreased thermal plasticity and a dampened transcriptional response during development. In recent years, the Nechako river has reached 21°C by the end of June, and at this temperature, a decrease in sturgeon performance is evident in most of the traits measured. As such, the thermal thresholds identified here suggest current temperature regulations may not be suitable for developing white sturgeon and future recruitment.
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Affiliation(s)
- Madison L Earhart
- Corresponding author: Department of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, BC V6T 1Z4, Canada. . Tel.: 204-799-9338
| | - Tessa S Blanchard
- Department of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, BC V6T 1Z4, Canada
| | - Phillip R Morrison
- Department of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, BC V6T 1Z4, Canada
- Department of Resource Management and Protection, and Biology Department, Vancouver Island University, 900 Fifth Street Nanaimo, BC V9R 5S5, Canada
| | - Nicholas Strowbridge
- Department of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, BC V6T 1Z4, Canada
- School of Biodiversity, One Health, & Veterinary Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, 464 Bearsden Rd, Bearsden, Glasgow G61 1QH, UK
| | - Rachael J Penman
- Department of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, BC V6T 1Z4, Canada
- Instreams fisheries research, 2323 Boundary Rd Unit 115, Vancouver, BC V5M 4V8, Canada
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, BC V6T 1Z4, Canada
| | - Patricia M Schulte
- Department of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, BC V6T 1Z4, Canada
| | - Daniel W Baker
- Department of Fisheries and Aquaculture, Vancouver Island University, 900 Fifth Street, Nanaimo, BC V9R 5S5, Canada
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