Using physiology to recover imperiled smelt species

Yanagitsuru, Yuzo R.; Davis, Brian A.; Baerwald, Melinda R.; Sommer, Ted; Fangue, Nann A.

doi:10.1016/bs.fp.2022.04.012

Cited by 4 publications

(3 citation statements)

References 107 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The delta smelt ( Hypomesus transpacificus ) is a small, semi-anadromous fish endemic to the upper SFE ( Moyle, 2002 ; Moyle et al, 2018 ; Yanagitsuru et al, 2022 ). Due to their exceptionally sensitive nature and unique life history, delta smelt have become an indicator species for ecosystem health ( Moyle et al, 2016 , 2019 ).…”

Section: Introductionmentioning

confidence: 99%

“…These changes have negatively impacted delta smelt abundance, as these fish are commonly associated with the low salinity zone (<6 psu), moderate temperatures (7–25°C), and mid-turbid waters (10–50 NTU) ( Swanson et al, 2000 ; Feyrer et al, 2007 ; Nobriga et al, 2008 ; Sommer and Mejia, 2013 ). Understanding how habitat degradation and change affect the physiology and performance of delta smelt is imperative for setting environmental regulations and offering recommendations for rearing and supplementation of the wild population ( Yanagitsuru et al, 2022 ).…”

Section: Introductionmentioning

confidence: 99%

“…Based on climate change projections, industrial competition for water usage, and knowledge of their physiological vulnerabilities and complex life histories, delta smelt are likely to go extinct in the wild in the next 1–5 years without effective and immediate management intervention ( Brown et al, 2013 , 2016 ; Komoroske et al, 2014 ; Jeffries et al, 2016 ; Moyle et al, 2018 , 2019 ; Hobbs et al, 2019 ; Bork et al, 2020 ). Consequently, current research aimed to conserve the delta smelt has shifted to focus on informing hatchery-based supplementation, which was initiated in winter 2021–2022 ( Yanagitsuru et al, 2022 ). The UC Davis Fish Conservation and Culture Laboratory (FCCL) is currently rearing a genetically managed refuge population for the purpose of both research and safeguarding the species against extinction ( Baskerville-Bridges et al, 2005 ; Fisch et al, 2013 ; Lindberg et al, 2013 ).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of turbidity, temperature and predation cue on the stress response of juvenile delta smelt

Pasparakis

Lohroff

Biefel

et al. 2023

Conservation Physiology

View full text Add to dashboard Cite

The San Francisco Estuary (SFE) is one of the most degraded ecosystems in the United States, and organisms that inhabit it are exposed to a suite of environmental stressors. The delta smelt (Hypomesus transpacificus), a small semi-anadromous fish endemic to the SFE and considered an indicator species, is close to extinction in the wild. The goal of this study was to investigate how environmental alterations to the SFE, such as reductions in turbidities, higher temperatures and increased prevalence of invasive predators affect the physiology and stress response of juvenile delta smelt. Juvenile delta smelt were exposed to two temperatures (17 and 21°C) and two turbidities (1–2 and 10–11 NTU) for 2 weeks. After the first week of exposure, delta smelt were exposed to a largemouth bass (Micropterus salmoides) predator cue at the same time every day for 7 days. Fish were measured and sampled on the first (acute) and final (chronic) day of exposures to predator cues and later analyzed for whole-body cortisol, glucose, lactate, and protein. Length and mass measurements were used to calculate condition factor of fish in each treatment. Turbidity had the greatest effect on juvenile delta smelt and resulted in reduced cortisol, increased glucose and lactate, and greater condition factor. Elevated temperatures reduced available energy in delta smelt, indicated by lower glucose and total protein, whereas predator cue exposure had negligible effects on their stress response. This is the first study to show reduced cortisol in juvenile delta smelt held in turbid conditions and adds to the growing data that suggest this species performs best in moderate temperatures and turbidities. Multistressor experiments are necessary to understand the capacity of delta smelt to respond to the multivariate and dynamic changes in their natural environment, and results from this study should be considered for management-based conservation efforts.

show abstract