Coldwater fish in a warm water world: Implications for predation of salmon smolts during estuary transit

Nobriga, Matthew L.; Michel, C.; Johnson, Rachel C.; Wikert, John D.

doi:10.1002/ece3.7840

Cited by 15 publications

(27 citation statements)

References 85 publications

(121 reference statements)

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“…Munsch et al (2019) found nonsignificant negative correlations between winter precipitation and April water temperatures. Lastly, Nobriga et al (2021) found negative relationships between flow and water temperature on the Sacramento and San Joaquin Rivers within the Delta in April, May, and June.…”

Section: Discussionmentioning

confidence: 98%

Seasonally variable relationships between surface water temperature and inflow in the upper San Francisco Estuary

Bashevkin

Mahardja

2022

Limnology & Oceanography

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Water temperature and inflow are key environmental drivers in aquatic systems that are linked through a causal web of factors including climate, weather, water management, and their downstream linkages. However, we do not yet fully understand the relationship between inflow and water temperature, especially in complex managed systems such as estuaries. The San Francisco Estuary is the center of a critical water supply infrastructure and home to a deteriorating ecosystem with several declining fish species at the warm edge of their thermal range. We used generalized additive modeling of long‐term monitoring data to evaluate the relationship between inflow and water temperature along with its spatio‐seasonal variability. Most commonly, we found a negative temperature‐inflow relationship in which water temperatures increased as inflow decreased, up to 2°C from high‐ to low‐inflow years. However, the opposite (positive) relationship was observed in the winter months, and in the western (downstream) regions from July–September, up to − 1.2°C from high‐ to low‐inflow years. These results were upheld by models that included the long‐term temperature trend or used salinity as a proxy for location. Upstream factors likely played the biggest role in the summer when local precipitation is negligible, whereas local precipitation and the related weather conditions may drive much of the winter pattern. Although further mechanistic studies are needed to infer the direct effect of dam releases on water temperatures, these results provide a broader understanding of the impacts of flood and drought dynamics for those tasked with managing estuarine ecosystems.

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Section: Discussionmentioning

confidence: 98%

Seasonally variable relationships between surface water temperature and inflow in the upper San Francisco Estuary

Bashevkin

Mahardja

2022

Limnology & Oceanography

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“…high temperatures; McCullough, 1999 ) or impact predation rates (e.g. predator species; Nobriga et al, 2021 ), factors that will vary by rearing strategy. Increasing survival for all juvenile rearing strategies would help sustain populations via the portfolio effect ( Sturrock et al , 2020 ; Cordoleani et al, 2021 ).…”

Section: Discussionmentioning

confidence: 99%

“…Although survival during juvenile outmigration decreases as temperature increases ( Michel, 2019 ), the precise temperature-dependent mechanisms impacting survival (e.g. juvenile metabolism, disease, predation rates) are not clear ( Nobriga et al, 2021 ). Future work should quantify survival for other rearing strategies as well as during juvenile outmigration, although we note the difficulty of defining the spatial–temporal movements of juveniles as well as identifying specific runs and populations from juveniles.…”

Section: Discussionmentioning

confidence: 99%

Quantification of thermal impacts across freshwater life stages to improve temperature management for anadromous salmonids

FitzGerald

Martin

2022

Conservation Physiology

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Water temperature is the major controlling factor that shapes the physiology, behaviour and, ultimately, survival of aquatic ectotherms. Here we examine temperature effects on the survival of Chinook salmon (Oncorhynchus tshawytscha), a species of high economic and conservation importance. We implement a framework to assess how incremental changes in temperature impact survival across populations that is based on thermal performance models for three freshwater life stages of Chinook salmon. These temperature-dependent models were combined with local spatial distribution and phenology data to translate spatial–temporal stream temperature data into maps of life stage-specific physiological performance in space and time. Specifically, we converted temperature-dependent performance (i.e. energy used by pre-spawned adults, mortality of incubating embryos and juvenile growth rate) into a common currency that measures survival in order to compare thermal effects across life stages. Based on temperature data from two abnormally warm and dry years for three managed rivers in the Central Valley, California, temperature-dependent mortality during pre-spawning holding was higher than embryonic mortality or juvenile mortality prior to smolting. However, we found that local phenology and spatial distribution helped to mitigate negative thermal impacts. In a theoretical application, we showed that high temperatures may inhibit successful reintroduction of threatened Central Valley spring-run Chinook salmon to two rivers where they have been extirpated. To increase Chinook salmon population sizes, especially for the threatened and declining spring-run, our results indicate that adults may need more cold-water holding habitat than currently available in order to reduce pre-spawning mortality stemming from high temperatures. To conclude, our framework is an effective way to calculate thermal impacts on multiple salmonid populations and life stages within a river over time, providing local managers the information to minimize negative thermal impacts on salmonid populations, particularly important during years when cold-water resources are scarce.

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“…Striped Bass ( Morone saxatilis ) rarely occur this far upstream, especially in the fall (M. Johnson, CDFW, personal communication, 2020), and the controlled cold‐water dam releases that enable winter‐run egg incubation (Johnson & Lindley, 2016; Martin et al, 2017), likely limit Micropterus sp. occurrence and foraging (Lawrence et al, 2012; Layher et al, 1987; Nobriga et al, 2021).…”

Section: Methodsmentioning

confidence: 99%

Riverine fish density, predator–prey interactions, and their relationships with artificial light at night

et al. 2022

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Artificial light at night (ALAN) has emerged as a prevalent anthropogenic stressor in many aquatic ecosystems impacting a wide range of taxa and ecological processes. In fishes, ALAN attracts both predators and prey, potentially resulting in increased predation mortality and sublethal impacts. Increased predation mortality is especially problematic in anadromous fishes, given that many populations are diminished and out‐migrating juveniles must transit illuminated waterways. Additionally, ALAN management is complex, because lighting benefits human safety, economies, and recreational pursuits. The Sundial Bridge (Redding, CA) is an iconic illuminated structure that spans a section of the little remaining spawning habitat of the endangered winter‐run Chinook Salmon. It was hypothesized that bridge ALAN increased Rainbow Trout predation of winter‐run fry, and a lighting management plan was implemented. However, ALAN impacts on this predator–prey interaction and species‐specific responses were unknown. Therefore, we used tethered salmonid fry and ARIS sonar cameras to determine whether variable ALAN treatments (0%, 25%, 50%, and 100% intensity) altered Rainbow Trout density (RTD) and fry predation risk, while investigating the temporal relationships of RTD with ALAN. ALAN significantly increased RTD on river right when any amount of ALAN was present, potentially leading to competition and fitness consequences; RTD did not change significantly in response to ALAN on river left. Although RTD generally increased in response to ALAN, salmonid fry predation was almost nonexistent. Therefore, while ALAN may decrease out‐migrant survival in other waterways, there was no evidence at our study site. Furthermore, the discrepancies between riverbanks demonstrate the complexity of ALAN and how it interacts with other environmental parameters potentially providing optimal foraging habitat. The Rainbow Trout attraction to ALAN, which occurred immediately with diminishing ambient light, indicates that complete ALAN removal may be necessary to mitigate ecological consequences of ALAN. When removal is unrealistic, ALAN should be diminished as early in the night as possible to minimize aquatic ecosystem impacts, while maintaining benefits for human populations.

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Coldwater fish in a warm water world: Implications for predation of salmon smolts during estuary transit

Cited by 15 publications

References 85 publications

Seasonally variable relationships between surface water temperature and inflow in the upper San Francisco Estuary

Seasonally variable relationships between surface water temperature and inflow in the upper San Francisco Estuary

Quantification of thermal impacts across freshwater life stages to improve temperature management for anadromous salmonids

Riverine fish density, predator–prey interactions, and their relationships with artificial light at night

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