Evaluation of a large-scale flow manipulation to the upper San Francisco Estuary: Response of habitat conditions for an endangered native fish

Abstract Exotic species have been implicated as a major threat to native freshwater fish communities in the Unites States. The San Francisco Estuary watershed has been recognized as one of the most invaded systems where exotics often dominate the fish community. On October 6, 2014, members of the U.S. Fish and Wildlife Service detected a previously unknown exotic fish in a disconnected pool immediately upstream from the Chowchilla Bifurcation Structure in the San Joaquin River, a major tributary of the San Francisco Estuary. A member of the U.S. Fish and Wildlife Service initially identified the fish as an Oriental Weatherfish Misgurnus anguillicaudatus using external morphological characteristics. We conducted additional fish sampling near the Chowchilla Bifurcation Structure in November 2014 and collected a total of six additional specimens in disconnected pool habitats. Unexpectedly, genetic and meristic techniques revealed that these specimens were Large-Scale Loach Paramisgurnus dabryanus. To our knowledge this is the first confirmed occurrence of Large-Scale Loach in the United States and the suspected pathway of introduction is release from aquaria. Very little is known about the population in the San Joaquin River. We recommend further evaluation of the ecology, distribution, and abundance of Large-Scale Loach to better understand their potential impact on the fish communities of the San Joaquin River and the likelihood of establishment throughout the United States.

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Persistence of native fishes in small streams of the urbanized San Francisco Estuary, California: acknowledging the role of urban streams in native fish conservation

Aquatic Conservation Marine and Freshwater Ecosystems ◽

10.1002/aqc.1208 ◽

2011 ◽

Vol 21 (5) ◽

pp. 472-483 ◽

Cited By ~ 5

Author(s):

Robert A. Leidy ◽

Kristina Cervantes-Yoshida ◽

Stephanie M. Carlson

Keyword(s):

San Francisco ◽

Urban Streams ◽

San Francisco Estuary ◽

Native Fish ◽

Fish Conservation ◽

Small Streams ◽

Native Fishes

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Evaluation of a large-scale flow manipulation to the upper San Francisco Estuary: Response of habitat conditions for an endangered native fish

10.1101/2020.06.02.129429 ◽

2020 ◽

Author(s):

Ted Sommer ◽

Rosemary Hartman ◽

Michal Koller ◽

Michael Koohafkan ◽

J. Louise Conrad ◽

...

Keyword(s):

San Francisco ◽

The United States ◽

San Francisco Estuary ◽

Sacramento River ◽

Habitat Conditions ◽

Delta Smelt ◽

Low Salinity ◽

Low Salinity Water ◽

Salinity Water ◽

General Response

AbstractWhile flow is known to be a major driver of estuarine ecosystems, targeted flow manipulations are rare because tidal systems are extremely variable in space and time, and because the necessary infrastructure is rarely available. In summer 2018 we used a unique water control structure in the San Francisco Estuary (SFE) to direct a managed flow pulse into Suisun Marsh, one of the largest contiguous tidal marshes on the west coast of the United States. The action was designed to increase habitat suitability for the endangered Delta Smelt Hypomesus transpacificus, a small osmerid fish endemic to the upper SFE. The approach was to operate the Suisun Marsh Salinity Control Gates (SMSCG) in conjunction with increased Sacramento River tributary inflow to direct an estimated 160 × 106 m3 pulse of low salinity water into Suisun Marsh during August, a critical time period for juvenile Delta Smelt rearing. Three-dimensional modeling showed that directing additional low salinity water into Suisun Marsh (“Flow Action”) substantially increased the area of low salinity habitat for Delta Smelt that persisted beyond the period of SMSCG operations. Field monitoring showed that turbidity and chlorophyll were at higher levels in Suisun Marsh, representing better habitat conditions, than the upstream Sacramento River region throughout the study period. The Flow Action had no substantial effects on zooplankton abundance, nor did Suisun Marsh show enhanced levels of these prey species in comparison to the Sacramento River. Fish monitoring data suggested that small numbers of Delta Smelt colonized Suisun Marsh from the Sacramento River during the Flow Action, further supporting our hypothesis that the Flow Action would benefit this rare species. Our study provides insight into both the potential use of targeted flow manipulations to support endangered fishes such as Delta Smelt, and into the general response of estuarine habitat to flow management.

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Can Plants Be Engineers?

Frontiers for Young Minds ◽

10.3389/frym.2021.625070 ◽

2021 ◽

Vol 9 ◽

Author(s):

J. Louise Conrad

Keyword(s):

San Francisco ◽

Water Flow ◽

Fish Species ◽

Aquatic Ecosystems ◽

Native Species ◽

Ecosystem Engineer ◽

Water Clarity ◽

Ecosystem Engineers ◽

San Francisco Estuary ◽

Native Fish

When we think of engineers, we think of making a machine, like a car. Are there engineers for ecosystems? When an organism can make big changes to its environment, we call it an ecosystem engineer. In aquatic ecosystems like the San Francisco Estuary, underwater plants can be important ecosystem engineers because they can change water flow and water clarity. In the Estuary, a plant called Brazilian waterweed, which was introduced by humans, is one of the most important ecosystem engineers. With its leaves and stems, this plant traps tiny particles floating in the water, making the water clearer. Clearer water has made it easier for more plants to grow and these changes helped some non-native fish species to increase in number, while some native species declined. Introduction of Brazilian waterweed has led to an entirely different ecosystem, which has also affected how people use and take care of the Estuary.

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Introduction of Bluefin Killifish (Lucania goodei) into the Sacramento–San Joaquin Delta

San Francisco Estuary and Watershed Science ◽

10.15447/sfews.2020v18iss2art3 ◽

2020 ◽

Vol 18 (2) ◽

Author(s):

Brian Mahardja ◽

Andrew Goodman ◽

Alisha Goodbla ◽

Andrea Schreier ◽

Catherine Johnston ◽

...

Keyword(s):

San Francisco ◽

Juvenile Fish ◽

Ecological Impact ◽

Monitoring Program ◽

San Francisco Estuary ◽

Native Fish ◽

Close Relative ◽

Proactive Management ◽

Lucania Goodei ◽

Bluefin Killifish

Biological invasion by non-native species has been identified as one of the major threats to native fish communities worldwide. The fish community of San Francisco Estuary is no exception, as the estuary has been recognized as one of the most invaded on the planet and the system has been impacted significantly by these invasions. Here, we summarize the introduction and probable establishment of a new species in the Sacramento–San Joaquin Delta, the Bluefin Killifish (Lucania goodei), as discovered by the US Fish and Wildlife Service Delta Juvenile Fish Monitoring Program (DJFMP). The DJFMP has conducted a large-scale beach seine survey since 1976, and it is the longest-running monitoring program in the San Francisco Estuary that extensively monitors the shallow-water nearshore habitat. Possibly introduced as discarded aquarium fish within the vicinity of the Delta Cross Channel, Bluefin Killifish is a close relative of the Rainwater Killifish (Lucania parva), another non-native fish species that has been present in the San Francisco Estuary system for decades. Studies in their native range suggest that Bluefin Killifish will fill a similar niche to Rainwater Killifish, albeit with a more freshwater distribution. The potential ecological impact of Bluefin Killifish remains unclear in the absence of additional studies. However, we have been able to track the spread of the species within the Sacramento–San Joaquin Delta through the existence of long-term monitoring programs. Our findings demonstrate the value of monitoring across various habitats for the early detection and proactive management of invasive species.

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Geospatial Tools for the Large-Scale Monitoring of Wetlands in the San Francisco Estuary: Opportunities and Challenges

San Francisco Estuary and Watershed Science ◽

10.15447/sfews.2019v17iss2art2 ◽

2019 ◽

Vol 17 (2) ◽

Author(s):

Sophie Taddeo ◽

◽

Iryna Dronova

Keyword(s):

San Francisco ◽

Large Scale ◽

San Francisco Estuary ◽

Geospatial Tools

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DYNAMICS OF LARGE SCALE FLOW AND ITS EFFECT ON HEAT TRANSFER IN TURBULENT CONVECTION

10.1615/ihtc16.cov.023932 ◽

2018 ◽

Author(s):

Arnab Kumar De ◽

P. K. Mishra

Keyword(s):

Heat Transfer ◽

Large Scale ◽

Turbulent Convection ◽

Large Scale Flow

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Supporting Restoration Decisions through Integration of Tree-Ring and Modeling Data: Reconstructing Flow and Salinity in the San Francisco Estuary over the Past Millennium

Water ◽

10.3390/w13152139 ◽

2021 ◽

Vol 13 (15) ◽

pp. 2139

Author(s):

Paul H. Hutton ◽

David M. Meko ◽

Sujoy B. Roy

Keyword(s):

San Francisco ◽

Tree Ring ◽

San Francisco Estuary ◽

Salinity Intrusion ◽

Estuarine Ecosystem ◽

Freshwater Flow ◽

The Past ◽

Decadal Scale ◽

Tree Ring Data ◽

Past Millennium

This work presents updated reconstructions of watershed runoff to San Francisco Estuary from tree-ring data to AD 903, coupled with models relating runoff to freshwater flow to the estuary and salinity intrusion. We characterize pre-development freshwater flow and salinity conditions in the estuary over the past millennium and compare this characterization with contemporary conditions to better understand the magnitude and seasonality of changes over this time. This work shows that the instrumented flow record spans the range of runoff patterns over the past millennium (averaged over 5, 10, 20 and 100 years), and thus serves as a reasonable basis for planning-level evaluations of historical hydrologic conditions in the estuary. Over annual timescales we show that, although median freshwater flow to the estuary has not changed significantly, it has been more variable over the past century compared to pre-development flow conditions. We further show that the contemporary period is generally associated with greater spring salinity intrusion and lesser summer–fall salinity intrusion relative to the pre-development period. Thus, salinity intrusion in summer and fall months was a common occurrence under pre-development conditions and has been moderated in the contemporary period due to the operations of upstream reservoirs, which were designed to hold winter and spring runoff for release in summer and fall. This work also confirms a dramatic decadal-scale hydrologic shift in the watershed from very wet to very dry conditions during the late 19th and early 20th centuries; while not unprecedented, these shifts have been seen only a few times in the past millennium. This shift resulted in an increase in salinity intrusion in the first three decades of the 20th century, as documented through early records. Population growth and extensive watershed modification during this period exacerbated this underlying hydrologic shift. Putting this shift in the context of other anthropogenic drivers is important in understanding the historical response of the estuary and in setting salinity targets for estuarine restoration. By characterizing the long-term behavior of San Francisco Estuary, this work supports decision-making in the State of California related to flow and salinity management for restoration of the estuarine ecosystem.

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