Large‐Scale Flow Management Action Drives Estuarine Ecological Response

Beakes, Michael P.; Graham, Cory; Conrad, J. Louise; White, James R.; Koohafkan, Michael; Durand, John R.; Sommer, Ted

doi:10.1002/nafm.10529

Cited by 4 publications

(4 citation statements)

References 56 publications

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“…In the upper estuary, temperature management during dry years may be possible through targeted spring flow releases from reservoirs and manipulation of infrastructure such as the Suisun Marsh Salinity Control Gates (Sommer, 2020). These controlled releases may also stimulate phytoplankton and zooplankton production in the low salinity zone (Beakes et al, 2020; Sommer et al, 2020), therefore benefitting juvenile herring. On the other hand, juvenile herring are generally associated with cool, salty conditions in spring, so they may mostly benefit from the combination of seasonally favorable coastal upwelling events and low flows that expand their range upriver.…”

Section: Discussionmentioning

confidence: 99%

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.

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Section: Discussionmentioning

confidence: 99%

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

et al. 2023

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“…However, the salinity control gates only operate from October to May, as needed to meet salinity standards measured at monitoring stations in Suisun Marsh. Thus, there is currently salinity mitigation via the gates only during the early portion of the waterfowl breeding season, but not from June to August, although a pilot program in 2018 tested the feasibility of operating the gates in August to maintain suitable habitat for the endangered Delta Smelt (Hypomesus transpacificus; Beakes et al 2021).…”

Section: Discussionmentioning

confidence: 99%

Wetland Availability and Salinity Concentrations for Breeding Waterfowl in Suisun Marsh, California

Schacter¹,

Peterson²,

Herzog³

et al. 2021

SFEWS

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Availability of wetlands with low salinities during the breeding season can influence waterfowl reproductive success and population recruitment. Salinities as low as 2 ppt (3.6 mScm–1) can impair duckling growth and influence behavior, with mortality occurring above 9 ppt (14.8 mScm–1). We used satellite imagery to quantify the amount of available water, and sampled surface water salinity at Grizzly Island, in the brackish Suisun Marsh, at three time-periods during waterfowl breeding (April, May, July) over 4 years (2016–2019). More water was available and salinity was lower during wetter years (2017, 2019) than during drier years (2016, 2018), and the amount of water in wetlands decreased 73%–86% from April to July. Across all time-periods and years, the majority (64%–100%) of wetland habitat area had salinities above what has been shown to negatively affect ducklings (> 2 ppt), and up to 42% of wetland area had salinities associated with duckling mortality (> 9 ppt). During peak duckling production in May, 81%–95% of available water had salinity above 2 ppt, and 5%–21% was above 9 ppt. In May of the driest year (2016), only 0.5 km2 of low-salinity water (< 2 ppt) was available to ducklings in the study area, compared to 2.6 km2 in May of the wettest year (2017). Private duck clubs own the majority of wetland habitat at Grizzly Island and consistently had a greater percentage of land flooded during summer than did publicly owned wetlands, but private wetlands generally had higher salinities than public wetlands, likely because they draw from higher-salinity water sources. By July, few wetlands remained flooded, and most had salinities high enough to impair duckling growth and survival. Local waterfowl populations would benefit from management practices that provide fresher water during peak duckling production in May and retain more water through July.

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“…Hence, understanding potential drivers of flow-abundance relationships has been a vibrant area of research for decades. This has led to research on the effects of seasonal flow on many factors, including gravitational circulation (Schoellhamer and Burau 1998), water diversions (Kimmerer and Nobriga 2008), spawning habitat (Sommer et al 1997), rearing habitat (Kimmerer et al 2013), zooplankton behavior (Kimmerer et al 2002), and access to marsh habitat (Sommer et al 2020a;Beakes et al 2021). Inundation of floodplain habitat has been a particularly fruitful area of research since seasonal flooding is a unique characteristic of wetter years (Sommer et al 2001).…”

Section: Follow the Signal Of Environmental Patternsmentioning

confidence: 99%

Data to Decisions: How to Make Science More Relevant for Management of the San Francisco Estuary

Sommer¹,

Conrad²,

Culberson³

2023

SFEWS

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Science is the foundation for a wide range of activities, including evaluation, innovation, and technology, which in turn support management. Without good science, resource management in regions such as the estuary is handicapped, and must proceed with outdated conceptual models, operating strategies, and technologies. At the same time, we recognize that poor communication can interfere with conversations between scientists and managers, even when high-quality data and publications are available. In this essay, we have tried to address an important part of this issue: helping scientists to understand how to produce actionable science. Our hope is that these suggestions will, at the least, help improve dialog between scientists and the managers responsible for the estuary’s resources.

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Large‐Scale Flow Management Action Drives Estuarine Ecological Response

Cited by 4 publications

References 56 publications

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

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

Wetland Availability and Salinity Concentrations for Breeding Waterfowl in Suisun Marsh, California

Data to Decisions: How to Make Science More Relevant for Management of the San Francisco Estuary

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