Shallow-Water Piscivore-Prey Dynamics in California's Sacramento-San Joaquin Delta

Nobriga, Matthew L.; Feyrer, Frederick

doi:10.15447/sfews.2007v5iss2art4

Cited by 64 publications

(91 citation statements)

References 46 publications

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“…Our study and others (Feyrer and Healey 2003;Toft et al 2003;Grimaldo et al 2004;Nobriga et al 2005;Nobriga and Feyrer 2007) show that native and introduced fishes in the Delta use a variety of habitats and that their trophic pathways vary with their body size and prey selection. Others have shown that physical habitat for native fishes can also be defined by water quality conditions or some measure of freshwater inflow (Kimmerer 2002a(Kimmerer , 2002b.…”

Section: Consequences For Restorationsupporting

confidence: 69%

“…Although other studies have reported diet information for fishes in the Delta (Turner 1966a(Turner , 1966bToft et al 2003;Nobriga and Feyrer 2007), this is the first study we know of that shows the importance of littoral-based carbon (SAV-epiphytic macroalgae) to the nutrition of fishes in the Delta. The results presented here suggest that trophic connections between prey and fishes were Table 2. ESTUARINE FOOD WEB DYNAMICS 209 generally linked to their physical habitat (Deegan and Garritt 1997;Paterson and Whitfield 1997;Toft et al 2003), but small to modest energy contributions crossed between habitats, especially in open-water shoals.…”

Section: Major Food Web Pathwaysmentioning

confidence: 88%

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Dietary Segregation of Pelagic and Littoral Fish Assemblages in a Highly Modified Tidal Freshwater Estuary

2009

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Estuarine food webs are highly variable and complex, making identification of their trophic pathways difficult. Energy for the food web of the San Francisco Estuary is thought to be based largely on in situ phytoplankton production, but little attention has been paid to littoral habitats, where other energy sources may be important. We analyzed the stomach contents of over 960 juvenile fishes and the stable carbon and nitrogen isotope ratios of these fishes and their potential food resources in pelagic and littoral habitats from the tidal freshwater area of the estuary. The mixing model IsoSource was used to examine energy sources important to consumers. Our results show evidence of two predominant food web pathways. Pelagic fishes and some littoral fishes showed strong dependence on a zooplankton–phytoplankton trophic pathway. However, the majority of fishes in littoral habitats had diets and carbon isotope ratios consistent with energy arising from submerged aquatic vegetation and epiphytic macroalgae. IsoSource revealed that the overall majority of nutrition of littoral fishes originated from consumption of grazer amphipods. Examining both stable isotopes and stomach contents allowed us to identify a food web with contributions to resident fishes that had been previously underestimated in the estuary. This study provides insight to how estuarine food webs have changed over the last few decades and highlights why the functions of habitats must be understood for effective restoration planning.

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Section: Consequences For Restorationsupporting

confidence: 69%

Section: Major Food Web Pathwaysmentioning

confidence: 88%

Dietary Segregation of Pelagic and Littoral Fish Assemblages in a Highly Modified Tidal Freshwater Estuary

2009

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“…(Jacoby et al 2000;Lehman et al 2005Lehman et al , 2008 and the establishment of nuisance aquatic vegetation (largely E. densa and Eichhornia crassipes) (Brown and Michniuk 2007;Sousa et al 2009Sousa et al , 2010Yarrow et al 2009). Stands of E. densa alter the physical structure of Delta channels and support the colonization of non-native fishes such as sunfish (Centrarchidae), which are often able to outcompete or prey upon native fishes (See 2.30 Structure, below) Grimaldo et al 2004;Nobriga et al 2005;Nobriga and Feyrer 2007;Ferrari et al 2014).…”

Section: Hydrodynamicsmentioning

confidence: 99%

“…Presumably, low zooplankton density limits fish foraging effectiveness. Zooplankton make up an important part of most larval fish diets during the critical period of their ontogenetic development from yolk-sac larvae to juvenile stage (Nobriga 2002;Nobriga and Feyrer 2007). During this period, zooplankton blooms of sufficient magnitude must occur in proximity to larval fish to allow successful transition to the first feeding.…”

Section: Diagram 5-secondary Production To Predatorsmentioning

confidence: 99%

“…As piscivorous fish grow, they will opportunistically take small fish when available, but gut content analyses show continued exploitation of epibenthic invertebrates, even in larger fish such as striped bass and largemouth bass. For largemouth bass, red swamp crayfish (Procambarus clarkii) can be the dominant food item (Simenstad et al 2000;Nobriga and Feyrer 2007;Ferrari et al 2014). Linkage 5.31 shows the effect of predation by demersal fish on bivalves, which can be importantly locally, but has little control on the overall abundance of clams.…”

Section: Diagram 5-secondary Production To Predatorsmentioning

confidence: 99%

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A Conceptual Model of the Aquatic Food Web of the Upper San Francisco Estuary

Durand¹

2015

SFEWS

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Fish predation on a landscape scale

et al. 2020

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Predator–prey dynamics can have landscape‐level impacts on ecosystems, and yet, spatial patterns and environmental predictors of predator–prey dynamics are often investigated at discrete locations, limiting our understanding of the broader impacts. At these broader scales, landscapes often contain multiple complex and heterogeneous habitats, requiring a spatially representative sampling design. This challenge is especially pronounced in California’s Sacramento–San Joaquin River Delta, where managers require information on the landscape‐scale impacts of non‐native fish predators on multiple imperiled native prey fish populations. We quantified relative predation risk in the southern half of the Delta (South Delta) in 2017 using floating baited tethers that record the exact time and location of predation events. We selected 20 study sites using a generalized random tessellation stratified survey design, which allowed us to infer relationships between key environmental covariates and predation across a broader spatial scale than previous studies. Covariates included distance‐to‐nearest predators, water temperature, turbidity, depth, bottom slope, bottom roughness, water velocity, and distance‐to‐nearest riverbank and nearest aquatic vegetation bed. Model selection determined the covariates that best predicted relative predation risk: water temperature, time of day, mean predator distance, and river bottom roughness. Using this model, we estimated predation risk for the South Delta landscape at a 1‐day and 1‐km resolution. This effort identified hot spots of predation risk and allowed us to generate predicted survival for migrating fish transiting the South Delta. This methodology can be applied to other systems to evaluate spatio‐temporal dynamics in predation risk, and their biotic and abiotic predictors.

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Shallow-Water Piscivore-Prey Dynamics in California's Sacramento-San Joaquin Delta

Cited by 64 publications

References 46 publications

Dietary Segregation of Pelagic and Littoral Fish Assemblages in a Highly Modified Tidal Freshwater Estuary

Dietary Segregation of Pelagic and Littoral Fish Assemblages in a Highly Modified Tidal Freshwater Estuary

A Conceptual Model of the Aquatic Food Web of the Upper San Francisco Estuary

Fish predation on a landscape scale

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