Physiological effects of salinity on Delta Smelt, Hypomesus transpacificus

Kammerer, Brittany D.; Hung, Tien‐Chieh; Baxter, Randall D.

doi:10.1007/s10695-015-0131-0

Cited by 14 publications

(15 citation statements)

References 75 publications

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“…However, haematocrit may increase transiently after tagging, as evident in a study of chinook salmon Oncorhynchus tshawytscha (Walbaum) smolts that were surgically implanted with transmitters; haematocrit levels were elevated on day five after tagging compared with control smolts, but returned to control levels by day 21 (Martinelli, Hansel & Shively, ). Haematocrit levels may vary widely among species (Gallaugher & Farrell, ), but the present haematocrit levels (32%–35%) are only slightly higher than baseline levels of largemouth bass Micropterus salmoides (Lacepède) (Brownscombe et al., ) and comparable to juvenile coho salmon Oncorhynchus kisutch (Walbaum) (Morrison et al., ), two‐lined monocle bream Scolopsis bilineatus (Bloch) without parasites (Triki, Grutter, Bshary & Ros, ) and delta smelt Hypomesus transpacificus McAllister in fresh waters (Kammerer, Hung, Baxter & Teh, ). Pathogen infections often cause decreased haematocrit levels (Peixoto et al., ) and a temporary decrease following tagging may be related to an initial immune response or blood loss, with haematocrit levels returning to baseline levels as the healing progresses.…”

mentioning

confidence: 70%

Effects of acoustic telemetry transmitters on gill ventilation rate and haematocrit levels of round goby Neogobius melanostomus

Behrens

Svendsen

Deurs

et al. 2017

Fisheries Management Eco

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mentioning

confidence: 70%

Effects of acoustic telemetry transmitters on gill ventilation rate and haematocrit levels of round goby Neogobius melanostomus

Behrens

Svendsen

Deurs

et al. 2017

Fisheries Management Eco

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“…Once at UC Davis, fish were acclimated to three salinity treatments (0.4 psu [n = 18], 2.0 psu [n = 20] and 12.0 psu [n = 24]) for a minimum of three weeks. This period was chosen to provide sufficient time for Delta Smelt to acclimate to the higher salinities [51]. For reference, 0.1 psu was the minimum salinity at which Delta Smelt were collected during CDFW trawls between summer 2011 and 2014 (n = 1,933).…”

Section: Methodsmentioning

confidence: 99%

Foraging and metabolic consequences of semi-anadromy for an endangered estuarine fish

et al. 2017

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Diadromy affords fish access to productive ecosystems, increasing growth and ultimately fitness, but it is unclear whether these advantages persist for species migrating within highly altered habitat. Here, we compared the foraging success of wild Delta Smelt—an endangered, zooplanktivorous, annual, semi-anadromous fish that is endemic to the highly altered San Francisco Estuary (SFE)—collected from freshwater (<0.55 psu) and brackish habitat (≥0.55 psu). Stomach fullness, averaged across three generations of wild Delta Smelt sampled from juvenile through adult life stages (n = 1,318), was 1.5-fold higher in brackish than in freshwater habitat. However, salinity and season interacted, with higher fullness (1.7-fold) in freshwater than in brackish habitat in summer, but far higher fullness in brackish than freshwater habitat during fall/winter and winter/spring (1.8 and 2.0-fold, respectively). To examine potential causes of this interaction we compared mesozooplankton abundance, collected concurrently with the Delta Smelt, in freshwater and brackish habitat during summer and fall/winter, and the metabolic rate of sub-adult Delta Smelt acclimated to salinities of 0.4, 2.0, and 12.0 psu in a laboratory experiment. A seasonal peak in mesozooplankton density coincided with the summer peak in Delta Smelt foraging success in freshwater, and a pronounced decline in freshwater mesozooplankton abundance in the fall coincided with declining stomach fullness, which persisted for the remainder of the year (fall, winter and spring). In brackish habitat, greater foraging ‘efficiency’ (prey items in stomachs/mesozooplankton abundance) led to more prey items per fish and generally higher stomach fullness (i.e., a higher proportion of mesozooplankton detected in concurrent trawls were eaten by fish in brackish habitat). Delta Smelt exhibited no difference in metabolic rate across the three salinities, indicating that metabolic responses to salinity are unlikely to have caused the stomach fullness results. Adult migration and freshwater spawning therefore places young fish in a position to exploit higher densities of prey in freshwater in the late spring/summer, and subsequent movement downstream provides older fish more accessible prey in brackish habitat. Thus, despite endemism to a highly-altered estuary, semi-anadromy provided substantial foraging benefits to Delta Smelt, consistent with other temperate migratory fish.

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“…, Sommer and Mejia , Slater and Baxter , Kammerer et al. ), juvenile delta smelt density was unimodally related to salinity (as measured by EC) and velocity but positively related to calanoid density. And somewhat counter to our predictions of a unimodal relationship, smelt density showed a positive relationship to turbidity (i.e., a negative relationship to Secchi depth).…”

Section: Discussionmentioning

confidence: 92%

“…, Kammerer et al. ), this requires significant energetic resources which would otherwise go to movement, growth, and later reproduction. Although delta smelt appear to show an affinity for turbid waters (Sommer and Mejia )—likely to reduce predation by visual predators (Nobriga et al.…”

Section: Introductionmentioning

confidence: 99%

“…Smelt are generally observed in slightly saline water (Sommer and Mejia 2013) and are negatively affected by both extreme low and high salinities (Bennett 2005). While they can acclimate physiologically to a modest range of salinities (Hasenbein et al 2013, Kammerer et al 2016, this requires significant energetic resources which would otherwise go to movement, growth, and later reproduction. Although delta smelt appear to show an affinity for turbid waters (Sommer and Mejia 2013)-likely to reduce predation by visual predators (Nobriga et al 2008)-they also display decreased feeding performance with increased turbidity (Hasenbein et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Prey availability, environmental constraints, and aggregation dictate population distribution of an imperiled fish

Simonis¹,

Merz

2019

Ecosphere

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Accelerated global loss of fish species underscores an urgent need to elucidate constraints on spatial and temporal population patterns and to mitigate human‐mediated impacts accordingly. We analyzed 20 yr of trawl data using a spatiotemporally explicit, hierarchically Bayesian model to define density distributions of an imperiled anadromous fish—the delta smelt, Hypomesus transpacificus—in the heavily modified and highly used San Francisco Estuary. To reduce management reliance on an estuary‐wide annual population index that minimizes data resolution and ignores uncertainty, our model took a spatiotemporal approach and explicitly accounted for sampling and observation variation through both stochastic and deterministic elements. Our model demonstrated that juvenile smelt density has decreased over annual time and displays a distinct seasonal pattern (the combination of growth into the sampled size class, mortality, and movement into and out of the sampling frame) of increases in March–June followed by decreases in June–August. Smelt density was highly spatiotemporally autocorrelated and strongly tracked prey availability yet was also constrained by local hydrological factors (salinity, turbidity, velocity). Specifically, juvenile smelt preferred slightly saline, turbid, generally slow‐moving water with ample copepod prey. However, poor swimming capabilities reduced the capacity of juvenile smelt to mix throughout the estuary and find optimal habitat, emphasizing the importance of accounting for spatiotemporal autocorrelation in species distribution models. Further, whole‐estuary outflow appeared to influence the spatial distribution of covariates and juvenile smelt, such that smelt densities tended to peak closer to the marine zone at a lower maximal value when outflow was high. The predictions of our model accurately matched observed patterns of juvenile delta smelt catch while embracing uncertainty (although the predictions tended to exaggerate the total smelt catch variation via over‐predicted tail values). These results highlight that data‐driven improvements can be made to the analytical methods currently used to guide delta smelt management and lay the groundwork for mitigating the impacts of water use, flow regimes, habitat alteration, and climate change on an endangered species in a highly impacted and economically consequential habitat.

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Physiological effects of salinity on Delta Smelt, Hypomesus transpacificus

Cited by 14 publications

References 75 publications

Effects of acoustic telemetry transmitters on gill ventilation rate and haematocrit levels of round goby Neogobius melanostomus

Effects of acoustic telemetry transmitters on gill ventilation rate and haematocrit levels of round goby Neogobius melanostomus

Foraging and metabolic consequences of semi-anadromy for an endangered estuarine fish

Prey availability, environmental constraints, and aggregation dictate population distribution of an imperiled fish

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