Characterizing the stress response in juvenile Delta smelt exposed to multiple stressors

Christina Pasparakis; Alexandra N Wampler; Toni Lohroff; Francine DeCastro; Dennis E Cocherell; Evan W Carson; Tien-Chieh Hung; Richard E Connon; Nann A Fangue; Anne E Todgham

doi:10.1016/j.cbpa.2022.111303

Characterizing the stress response in juvenile Delta smelt exposed to multiple stressors

Comp Biochem Physiol A Mol Integr Physiol. 2022 Dec:274:111303. doi: 10.1016/j.cbpa.2022.111303. Epub 2022 Aug 29.

Authors

Affiliations

¹ Department of Environmental Toxicology, University of California Davis, Davis, CA, USA; Bodega Marine Laboratory, University of California Davis, Bodega Bay, CA, USA. Electronic address: cpasparakis@ucdavis.edu.
² Department of Wildlife, Fish and Conservation Biology, University of California Davis, Davis, CA, USA.
³ Department of Wildlife, Fish and Conservation Biology, University of California Davis, Davis, CA, USA; Department of Animal Science, University of California Davis, Davis, CA, USA.
⁴ Department of Animal Science, University of California Davis, Davis, CA, USA. Electronic address: https://twitter.com/Frantickled.
⁵ U.S. Fish and Wildlife Service, San Francisco Bay-Delta Fish and Wildlife Office, Sacramento, CA, USA.
⁶ Fish Conservation and Culture Laboratory, Department of Biological and Agricultural Engineering, University of California Davis, Davis, CA, USA.
⁷ School of Veterinary Medicine, Department of Anatomy, Physiology and Cell Biology, University of California Davis, Davis, CA, USA.
⁸ Department of Animal Science, University of California Davis, Davis, CA, USA.

PMID: 36049729
DOI: 10.1016/j.cbpa.2022.111303

Abstract

The Delta Smelt (Hypomesus transpacificus), once an abundant fish endemic to the Sacramento-San Joaquin Estuary, is now on the brink of extinction. Due to the high sensitivity of this species, knowledge of their stress response will be vital to their future survival and sustainability. Understanding the magnitude and kinetics of cortisol induction in Delta Smelt will provide valuable information when interpreting the degree of environmentally relevant stressors, such as warming and predator exposure. As little is known about the primary stress response and cortisol dynamics in Delta Smelt, the first aim of this study was to measure basal and maximal whole-body cortisol prior to and following exposure to a sublethal and significant netting stress at 17 and 21 °C. Our findings reveal that juvenile Delta Smelt held at 21 °C display an exacerbated stress response and a reduction in available energy compared to fish held at 17 °C. There was no evidence of the secondary stress response to the netting stress as whole-body glucose and lactate levels in treatment groups remained similar to basal values. The second aim of this study was to investigate the effect of a largemouth bass (Micropterus salmoides) predator cue, which was found to induce a significant increase in cortisol relative to control levels in juvenile Delta Smelt. Indices such as cortisol can be used as bioindicators of stress in the field and results from this study suggest that moderate temperatures and reduced predation are optimal release conditions during hatchery-based supplementation to minimize stress to this highly sensitive species.

Keywords: Climate change; Delta Smelt; Predation; Stress.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't

MeSH terms

Animals
Endangered Species
Environmental Biomarkers
Glucose
Hydrocortisone
Lactates
Osmeriformes* / physiology

Substances

Environmental Biomarkers
Lactates
Glucose
Hydrocortisone