Effects of Extreme Hydrologic Regimes on Juvenile Chinook Salmon Prey Resources and Diet Composition in a Large River Floodplain

Goertler, Pascale; Jones, Kristopher S.; Cordell, Jeffery R.; Schreier, Brian M.; Sommer, Ted

doi:10.1002/tafs.10028

Cited by 18 publications

(16 citation statements)

References 50 publications

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“…Previous research has shown that inundated Yolo Bypass floodplain habitat typically has substantially higher densities of phytoplankton, zooplankton, and drift invertebrates than the adjacent Sacramento River across a suite of water year types (Sommer et al 2001a(Sommer et al , 2001b2004;Goertler et al 2018). Our studies consistently showed https://doi.org/10.15447/sfews.2020v18iss3art3 that managed inundation of agricultural fields supported statistically higher levels of phytoplankton and invertebrates than the Sacramento River (Corline et al 2017).…”

Section: Flooded Farm Fields Support High Biological Productivitysupporting

confidence: 76%

“…Drift invertebrates are often a more substantial part of the food web in natural flood events in Yolo Bypass (Sommer et al 2001a(Sommer et al , 2001b(Sommer et al , 2004Benigno and Sommer 2009). Nonetheless, zooplankton densities can be relatively high in Yolo Bypass (as compared to the Sacramento River) during dry seasons and drought years (Frantzich et al 2018;Goertler et al 2018). The specific reasons for these differences include longer residence time and shallower depths in the Yolo Bypass than in adjacent perennial river channels (Sommer et al 2004).…”

Section: Flooded Farm Fields Support High Biological Productivitymentioning

confidence: 99%

“…We associate these results with the effects of extreme drought conditions that prevailed during the core of our study from 2012 through 2015. Although our field studies were conducted during a time of year when wild salmon have historically used the Yolo Bypass floodplain (Takata et al 2017;Goertler et al 2018), the extreme drought made for warm water temperatures, and resulted in our study site being one of the few inundated wetland locations in the region. As such, avian predators were attracted to the experimental fields, exacerbating salmon mortality during drainage.…”

Section: These Types Of Studies Generate Numerous Challengesmentioning

confidence: 99%

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Farm to Fish: Lessons from a Multi-Year Study on Agricultural Floodplain Habitat

Sommer¹,

Schreier²,

Conrad

et al. 2020

SFEWS

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Large areas of California’s historic floodplain have been separated from adjacent river channels by levee construction, allowing the development of an extensive agricultural industry. Based on successful partnerships between agriculture and conservation groups to support migrating waterfowl, we examined whether seasonally flooded rice fields could be modified to provide off-channel rearing habitat for juvenile Chinook Salmon Oncorhynchus tshawytscha. During winter and spring of 2012-2017, we conducted a series of experiments in Yolo Bypass and other regions of California’s Central Valley using hatchery Chinook Salmon as a surrogate for wild Chinook Salmon, the management target for our project. Overall, we found that seasonally flooded fields are highly productive, resulting in significantly higher levels of zooplankton and high Chinook Salmon growth rates as compared to the adjacent Sacramento River. We found similar results for multiple geographical areas in the Central Valley, and in different cover types, such as non-rice crops and fallow areas. Although field substrate type did not detectably affect fish growth and survival, connectivity with upstream and downstream areas appeared to drive fish occupancy, because rearing young salmon were generally attracted to inflow in the fields, and not all of the fish successfully emigrated off the fields without efficient drainage. In general, we faced numerous logistic and environmental challenges to complete our research. For example, periodic unmanaged floods in the Yolo Bypass made it difficult to schedule and complete experiments. During severe drought conditions, we found that managed agricultural habitats produced low and variable salmon survival results, likely because of periodically high temperatures and concentrated avian predation. In addition, our project required substantial landowner time and effort to install and maintain experimental fields. Recent and future infrastructure improvements in Yolo Bypass could substantially improve options for experimental work and broaden efforts to enhance salmon habitat.

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Section: Flooded Farm Fields Support High Biological Productivitysupporting

confidence: 76%

Section: Flooded Farm Fields Support High Biological Productivitymentioning

confidence: 99%

Section: These Types Of Studies Generate Numerous Challengesmentioning

confidence: 99%

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Farm to Fish: Lessons from a Multi-Year Study on Agricultural Floodplain Habitat

Sommer¹,

Schreier²,

Conrad

et al. 2020

SFEWS

Self Cite

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“…This timing was chosen as it is the time of year when juvenile Chinook Salmon are out-migrating through the Sacramento River and would likely have access to floodplain habitats during high flow events. Moreover, during lower flow periods fish can access the perennial channels of the floodplain by migrating upstream from the lower tidal reaches of the Sacramento system [ 21 ]. Hence, wild juvenile salmon were present in both Yolo Bypass and Sacramento River during the course of our experiments.…”

Section: Methodsmentioning

confidence: 99%

Detrital food web contributes to aquatic ecosystem productivity and rapid salmon growth in a managed floodplain

Jeffres

Holmes

Sommer³

et al. 2020

PLoS ONE

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Similar to many large river valleys globally, the Sacramento River Valley has been extensively drained and leveed, hydrologically divorcing river channels from most floodplains. Today, the former floodplain is extensively managed for agriculture. Lack of access to inundated floodplains is recognized as a significant contributing factor in the decline of native Chinook Salmon (Oncorhynchus tshawytscha). We observed differences in salmon growth rate, invertebrate density, and carbon source in food webs from three aquatic habitat types-leveed river channels, perennial drainage canals in the floodplain, and agricultural floodplain wetlands. Over 23 days (17 February to 11 March, 2016) food web structure and juvenile Chinook Salmon growth rates were studied within the three aquatic habitat types. Zooplankton densities on the floodplain wetland were 53x more abundant, on average, than in the river. Juvenile Chinook Salmon raised on the floodplain wetland grew at 0.92 mm/day, 5x faster than fish raised in the adjacent river habitat (0.18 mm/day). Two aquatic-ecosystem modeling methods were used to partition the sources of carbon (detrital or photosynthetic) within the different habitats. Both modeling approaches found that carbon in the floodplain wetland food web was sourced primarily from detrital sources through heterotrophic pathways, while carbon in the river was primarily photosynthetic and sourced from in situ autotrophic production. Hydrologic conditions typifying the ephemerally inundated floodplain-shallower depths, warmer water, longer water residence times and predominantly detrital carbon sources compared to deeper, colder, swifter water and a predominantly algal-based carbon source in the adjacent river channel-appear to facilitate the dramatically higher rates of food web production observed in the floodplain. These results suggest that hydrologic patterns associated with seasonal flooding facilitate river food webs to access floodplain carbon sources that contribute to highly productive heterotrophic energy pathways important to the production of fisheries resources.

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“…(Bouley and Kimmerer 2006;Kayfetz and Kimmerer 2017;Kimmerer et al 2018). In floodplains adjacent to the Delta, some cladocerans have also received attention, particularly Daphnia spp., due to their importance in the diet of juvenile salmonids (Goertler et al 2018;Corline et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Long-term trends in seasonality and abundance of three key zooplankters in the upper San Francisco Estuary

Bashevkin¹,

Burdi²,

Hartman³

et al. 2022

Preprint

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Zooplankton provide critical food for threatened and endangered fish species in the San Francisco Estuary (estuary). Reduced food supply has been implicated in the Pelagic Organism Decline of the early 2000s and further changes in zooplankton abundance, seasonality, and distribution may continue to threaten declining fishes. While we have a wealth of monitoring data, we know little about the abundance trends of many estuary zooplankton species. To fill these gaps., we reviewed past research and then examined trends in seasonality and abundance from 1972 to present of three key but understudied zooplankton species (Bosmina longirostris, Acanthocyclops spp., and Acartiella sinensis) that play important roles in the estuary food web. All three species were found in the stomach contents of important estuarine fishes. We fit Bayesian generalized additive mixed models of each species’ relationships with salinity, seasonality, year, and geography on an integrated database of zooplankton monitoring in the upper estuary. We found marked changes in the seasonality and overall abundance of each study species. B. longirostris no longer peaks in abundance in the fall months, Acanthocyclops spp. dramatically declined in all months and lost its strong relationship with salinity, and A. sinensis adult abundance has become increasingly driven by salinity while juveniles have developed wider seasonal abundance peaks. In this process, we have documented the relationship of each species with salinity and seasonality since the beginning of monitoring or their introduction, thus increasing our understanding of their ecology and importance in the estuary. These results can inform food web models, be paired with fish data to model the contributions of these species toward fish abundance trends, and be mirrored to elucidate other species’ trends in future studies.

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Effects of Extreme Hydrologic Regimes on Juvenile Chinook Salmon Prey Resources and Diet Composition in a Large River Floodplain

Cited by 18 publications

References 50 publications

Farm to Fish: Lessons from a Multi-Year Study on Agricultural Floodplain Habitat

Farm to Fish: Lessons from a Multi-Year Study on Agricultural Floodplain Habitat

Detrital food web contributes to aquatic ecosystem productivity and rapid salmon growth in a managed floodplain

Long-term trends in seasonality and abundance of three key zooplankters in the upper San Francisco Estuary

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