Forage Fish Larvae Distribution and Habitat Use During Contrasting Years of Low and High Freshwater Flow in the San Francisco Estuary

Grimaldo, Lenny; Burns, Jillian; Miller, Robert; Kalmbach, Andrew; Smith, April C.; Hassrick, Jason L.; Brennan, Colin

doi:10.15447/sfews.2020v18iss3art5

Cited by 26 publications

(38 citation statements)

References 51 publications

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“…Other sources of freshwater in the estuary include small streams and large tributaries (e.g., the Petaluma River). Fish and zooplankton were collected for this study during the spring of 2017, which was the year of highest freshwater flow from 1955 to 2020 (Grimaldo et al, 2020). During high flow years, distributions of pelagic fishes such as longfin smelt and Pacific herring shift seaward, generally tracking the salinity distribution (Grimaldo et al, 2020).…”

Section: Study Area and Sample Collectionmentioning

confidence: 99%

“…Larval fish and zooplankton from one tow were immediately preserved in 95% non-denatured ethyl alcohol (EtOH) and placed on ice for molecular diet analysis. The larval fish and zooplankton from the second tow were preserved in 2-4% formaldehyde (final conc., vol:vol) for use primarily in a separate study examining the distribution and abundance of larval longfin smelt and Pacific herring (Grimaldo et al, 2020), and for a study of the fish diets through morphological analysis.…”

Section: Study Area and Sample Collectionmentioning

confidence: 99%

“…Correspondingly, age-0 longfin smelt abundance is higher by almost two orders of magnitude during years with higher freshwater flow compared to years when freshwater flow is low (Kimmerer et al, 2009). Rearing conditions may be enhanced during high-flow years but mechanisms for effects of flow on rearing conditions are still largely unknown (Grimaldo et al, 2020). Pacific herring spawn adhesive eggs on substrates mainly in the seaward regions of the estuary but larvae can be broadly distributed throughout the estuary depending on freshwater flow.…”

Section: Introductionmentioning

confidence: 99%

“…Pacific herring spawn adhesive eggs on substrates mainly in the seaward regions of the estuary but larvae can be broadly distributed throughout the estuary depending on freshwater flow. For example, Grimaldo et al, (2020) observed larval herring in relatively modest abundance in the northern estuary during a low flow year which may be due either net landward movement via two-layer gravitational flow or some local spawning activity.…”

Section: Introductionmentioning

confidence: 99%

“…Rearing of longfin smelt and Pacific herring larvae may overlap in the SFE in some years (Grimaldo et al, 2020), thus we would expect them to have similar diets through foraging in a shared prey field when their spatial distributions are similar. Studies of feeding by larval longfin smelt to date are rare, but morphological gut content analyses of larvae have found copepods to be important prey, including Acanthocyclops spp., Pseudodiaptomus forbesi (Hobbs et al, 2006), and Eurytemora carolleeae (formerly E. affinis; Alekseev & Souissi 2011;Slater 2015).…”

Section: Introductionmentioning

confidence: 99%

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Feeding habits and novel prey of larval fishes in the northern San Francisco Estuary

Jungbluth

Burns

Grimaldo³

et al. 2020

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Food limitation can dampen survival and growth of fish during early development. To investigate prey diversity important to the planktivorous larval longfin smelt (Spirinchus thaleichthys) and Pacific herring (Clupea pallasii) from the San Francisco Estuary, we used DNA metabarcoding analysis of the cytochrome oxidase I gene on the guts of these fishes and on environmental zooplankton samples. Differential abundance analysis suggested that both species consumed the most abundant zooplankton at a lower rate than their availability in the environment. Both fish consumed the prey that were commonly available and relatively abundant. Prey taxa substantially overlapped between the two species (Schoener's index = 0.66), and alpha diversity analysis suggested high variability in the content of individual guts. Abundant prey taxa in both fish species included the copepods Eurytemora carolleeae, Acanthocyclops americanus, and A. robustus; the Acanthocyclops spp. are difficult to identify morphologically. A few uncommon prey in the diets hint at variable feeding strategies, such as herring (presumably egg) DNA in the longfin smelt diets, which suggests feeding near substrates. Herring consumed the small (<0.5 mm) copepod Limnoithona tetraspina more frequently (30%) than did smelt (2%), possibly indicating differences in foraging behavior or sensory abilities. Among the unexpected prey found in the diets was the cnidarian Hydra oligactis, the polychaete Dasybranchus sp., and a newly identified species Mesocyclops pehpeiensis. "Unknown" DNA was in 56% of longfin smelt diets and 57% of herring diets, and made up 17% and 21% of the relative read abundance in the two species, respectively. Our results suggest that these two fishes, which overlap in nursery habitat, also largely overlap in food resources necessary for larval survival.

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Section: Study Area and Sample Collectionmentioning

confidence: 99%

Section: Study Area and Sample Collectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Feeding habits and novel prey of larval fishes in the northern San Francisco Estuary

Jungbluth

Burns

Grimaldo³

et al. 2020

Preprint

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Disentangling abiotic and biotic controls of age‐0 Pacific herring population stability across the San Francisco Estuary

et al. 2023

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Pacific herring (Clupea pallasii) is an ecologically and commercially valuable forage fish in the North Pacific Ocean. However, knowledge gaps exist around the abiotic and biotic drivers behind its variable population dynamics—as well as on the ability of the species to show spatially structured trends that stabilize population portfolios in the face of environmental change. Here we examined how historical hydroclimatic variability in the San Francisco Estuary (California) has driven age‐0 Pacific herring population dynamics over 35 years. First, we used wavelet analyses to examine spatiotemporal variation and synchrony in the environment, focusing on two key variables: salinity and temperature. Next, we fitted multivariate autoregressive state‐space models to environmental and abundance time series to test for spatial structure and to parse out abiotic (salinity and temperature) from biotic influences (spawning and density dependence). Finally, we examined the stabilizing effects of spatially asynchronous population fluctuations (i.e., portfolio effects) across the estuary. Our results showed that temperature, but not salinity, fluctuated synchronously across regions on seasonal and decadal timescales. The top‐ranked model showed strong evidence of regional population structure and regional variation in population responses to the environment. As expected, age‐0 herring were generally associated with cooler, saltier conditions in spring. Density dependence was strong in all regions, suggesting that local factors influencing rearing conditions limited juvenile population growth across the estuary. Additionally, age‐0 abundance fluctuations were on average 15% more stable across the estuary than in individual regions, demonstrating that portfolio effects arising from population asynchrony have helped to stabilize recruitment across the estuary over the past four decades. We contend that ecosystem‐based fishery management strategies to restore eelgrass and tidal marsh rearing habitats could increase the carrying capacity of the estuary, further stabilizing the herring population and reducing the risk of fishery closures.

show abstract

Feeding habits and novel prey of larval fishes in the northern San Francisco Estuary

et al. 2021

Self Cite

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Food limitation can dampen the survival and growth of fish species during early development. To investigate prey diversity important to the planktivorous larval longfin smelt (Spirinchus thaleichthys) and Pacific herring (Clupea pallasii) from the San Francisco Estuary, we used DNA metabarcoding analysis of the cytochrome oxidase I gene on the guts of these fishes and on environmental zooplankton samples, in comparison with results from abundance analyses of zooplankton samples. Overall, both fish consumed the prey that were commonly available and relatively abundant: Diets were dominated by arthropods but also included soft‐bodied and difficult to identify organisms. Prey taxa substantially overlapped between the two species (Schoener's index = 0.66), and alpha diversity analysis suggested high variability in the content of guts from different individuals. Abundant prey taxa in both fish species included the copepods Eurytemora carolleeae, Acanthocyclops americanus, and A. robustus; Acanthocyclops spp. are difficult to distinguish morphologically. Differential abundance analysis suggested that both species consumed the most abundant zooplankton in lower proportions than their availability in the environment. A few uncommon prey observed in the diets may hint at feeding strategies employed by the larvae, such as herring DNA in the longfin smelt diets, suggesting feeding on eggs near substrates or schooling behavior. Herring consumed the small (<0.5 mm) copepod Limnoithona tetraspina much more frequently (30%) than did smelt (2%), possibly indicating differences in foraging behavior or sensory abilities. Among the unexpected prey found in the diets was the cnidarian Hydra oligactis, the polychaete Dasybranchus sp., and the copepod Mesocyclops pehpeiensis, a species not previously described in the San Francisco Estuary. Our findings illustrate the power of molecular methods in revealing feeding patterns and novel plankton diversity that can be undetectable with complementary morphological analysis methods.

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Forage Fish Larvae Distribution and Habitat Use During Contrasting Years of Low and High Freshwater Flow in the San Francisco Estuary

Cited by 26 publications

References 51 publications

Feeding habits and novel prey of larval fishes in the northern San Francisco Estuary

Feeding habits and novel prey of larval fishes in the northern San Francisco Estuary

Disentangling abiotic and biotic controls of age‐0 Pacific herring population stability across the San Francisco Estuary

Feeding habits and novel prey of larval fishes in the northern San Francisco Estuary

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