Pub Date : 2023-03-24DOI: 10.15447/sfews.2023v21iss1art2
I. Howard, D. Stahle, M. Torbenson, D. Granato-Souza, C. Poulsen
Subsets of annual and sub-annual tree-ring chronologies are used to reconstruct seasonal precipitation totals in northern California. The specific seasons selected for reconstruction are based on the strongest monthly precipitation signals recorded in the tree-ring data. Earlywood width of gray pine is best correlated with Oct-Dec precipitation at the onset of the wet season. Latewood width of ponderosa pine is correlated with Mar–Apr totals at the end of the wet season. These earlywood and latewood width chronologies are used to develop separate reconstructions of precipitation for the “autumn” (Oct–Dec) and “spring” (Mar–Apr) seasons. Total ring-width chronologies of blue oak are highly correlated with October–April precipitation totals and are used to reconstruct precipitation for the “wet season.” We then computed one additional skillful reconstruction by subtracting the reconstructed spring totals from the wet season precipitation estimates (i.e., “winter” [Oct–Feb]). We compare the winter and spring reconstructions because they are well calibrated and provide an interesting long-term perspective on the interaction of winter–spring precipitation amounts near March 1, when important reservoir management decisions are often made. Consecutive wet winter and very wet spring precipitation anomalies increased after 1950 in the instrumental and reconstructed time-series, often coinciding with the largest spring streamflow and flood events recorded on the American River at Folsom. Once the sub-annual tree-ring data can be improved, it may be possible to develop discrete reconstructions of early-, middle-, and late-season precipitation for the past 250 to 500 years, to help define natural variability and anthropogenic forcing of seasonal precipitation totals in California.
{"title":"The Flood Risk and Water Supply Implications of Seasonal Precipitation Reconstructions in Northern California","authors":"I. Howard, D. Stahle, M. Torbenson, D. Granato-Souza, C. Poulsen","doi":"10.15447/sfews.2023v21iss1art2","DOIUrl":"https://doi.org/10.15447/sfews.2023v21iss1art2","url":null,"abstract":"Subsets of annual and sub-annual tree-ring chronologies are used to reconstruct seasonal precipitation totals in northern California. The specific seasons selected for reconstruction are based on the strongest monthly precipitation signals recorded in the tree-ring data. Earlywood width of gray pine is best correlated with Oct-Dec precipitation at the onset of the wet season. Latewood width of ponderosa pine is correlated with Mar–Apr totals at the end of the wet season. These earlywood and latewood width chronologies are used to develop separate reconstructions of precipitation for the “autumn” (Oct–Dec) and “spring” (Mar–Apr) seasons. Total ring-width chronologies of blue oak are highly correlated with October–April precipitation totals and are used to reconstruct precipitation for the “wet season.” We then computed one additional skillful reconstruction by subtracting the reconstructed spring totals from the wet season precipitation estimates (i.e., “winter” [Oct–Feb]). We compare the winter and spring reconstructions because they are well calibrated and provide an interesting long-term perspective on the interaction of winter–spring precipitation amounts near March 1, when important reservoir management decisions are often made. Consecutive wet winter and very wet spring precipitation anomalies increased after 1950 in the instrumental and reconstructed time-series, often coinciding with the largest spring streamflow and flood events recorded on the American River at Folsom. Once the sub-annual tree-ring data can be improved, it may be possible to develop discrete reconstructions of early-, middle-, and late-season precipitation for the past 250 to 500 years, to help define natural variability and anthropogenic forcing of seasonal precipitation totals in California.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43031767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-03DOI: 10.15447/sfews.2023v20iss4art7
L. Windham‐Myers, P. Oikawa, S. Deverel, Dylan E. Chapple, J. Drexler, Dylan Stern
The aquatic landscapes of the Sacramento–San Joaquin Delta (hereafter, the Delta) and Suisun Bay represent both a significant past and future soil carbon stock. Historical alterations of hydrologic flows have led to depletion of soil carbon stocks via emissions of carbon dioxide (CO2), and loss of elevation as a result of subsidence. Optimizing ecosystem hydrology in the Delta and Suisun Bay could both reduce and reverse subsidence while also providing significant opportunities for climate mitigation and adaptation. Emissions of greenhouse gases (GHGs)—notably CO2, methane (CH4 ), and nitrous oxide (N2O)—contribute to global warming at different rates and intensities, requiring GHG accounting and modeling to assess the relative benefits of management options. Decades of data collection, model building, and map development suggest that past and current management actions have both caused—and can mitigate—losses of soil carbon. We review here the magnitude of potential GHG offsets, management options that may be achievable, and trade-offs of carbon storage under different land management. Using a land-use/land-cover framework to assess these management options, we describe the potential of three interventions (impoundment to reverse subsidence, agricultural management, and tidal reintroduction and/or maintained connectivity), both in acreage and radiative balance to clarify their relative influence on the region’s GHG balance today and in relation to its millennial history. From floodplains to farming to floating aquatic vegetation, we find specific scalable strategies to manage hydrology that can alter regional GHG balance. Preservation of soil carbon stocks and restoration of net atmospheric CO2 fluxes into soils are the primary route to net negative emissions in the Delta and Suisun Bay, with CH4 emission management occurring in a supporting role. Over a 40-year horizon of climate-mitigation markets, the resilience of different aquatic habitats introduces the most uncertainty, from expected and unexpected hydrologic changes associated with land, ocean, and operational water flows.
{"title":"Carbon Sequestration and Subsidence Reversal in the Sacramento-San Joaquin Delta and Suisun Bay: Management Opportunities for Climate Mitigation and Adaptation","authors":"L. Windham‐Myers, P. Oikawa, S. Deverel, Dylan E. Chapple, J. Drexler, Dylan Stern","doi":"10.15447/sfews.2023v20iss4art7","DOIUrl":"https://doi.org/10.15447/sfews.2023v20iss4art7","url":null,"abstract":"The aquatic landscapes of the Sacramento–San Joaquin Delta (hereafter, the Delta) and Suisun Bay represent both a significant past and future soil carbon stock. Historical alterations of hydrologic flows have led to depletion of soil carbon stocks via emissions of carbon dioxide (CO2), and loss of elevation as a result of subsidence. Optimizing ecosystem hydrology in the Delta and Suisun Bay could both reduce and reverse subsidence while also providing significant opportunities for climate mitigation and adaptation. Emissions of greenhouse gases (GHGs)—notably CO2, methane (CH4 ), and nitrous oxide (N2O)—contribute to global warming at different rates and intensities, requiring GHG accounting and modeling to assess the relative benefits of management options. Decades of data collection, model building, and map development suggest that past and current management actions have both caused—and can mitigate—losses of soil carbon. We review here the magnitude of potential GHG offsets, management options that may be achievable, and trade-offs of carbon storage under different land management. Using a land-use/land-cover framework to assess these management options, we describe the potential of three interventions (impoundment to reverse subsidence, agricultural management, and tidal reintroduction and/or maintained connectivity), both in acreage and radiative balance to clarify their relative influence on the region’s GHG balance today and in relation to its millennial history. From floodplains to farming to floating aquatic vegetation, we find specific scalable strategies to manage hydrology that can alter regional GHG balance. Preservation of soil carbon stocks and restoration of net atmospheric CO2 fluxes into soils are the primary route to net negative emissions in the Delta and Suisun Bay, with CH4 emission management occurring in a supporting role. Over a 40-year horizon of climate-mitigation markets, the resilience of different aquatic habitats introduces the most uncertainty, from expected and unexpected hydrologic changes associated with land, ocean, and operational water flows.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44160928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-03DOI: 10.15447/sfews.2023v20iss4art2
K. Boyer, Sam M. Safran, S. Khanna, Melissa V. Patten
Conversion of wetlands in the Sacramento–San Joaquin Delta beginning in the mid-1800s resulted in a pronounced shift from a wetland-dominated food web to one driven by open-water primary producers. Submersed and floating aquatic vegetation (SAV and FAV) now rank highest in potential net primary production (NPP) among producer groups, and provide a comparable amount of carbon to the detrital food web as marshes. However, important details of this contribution that relate to shifts in species composition and habitat extent were not understood. Here, we review how changes in aquatic vegetation influence NPP and trophic support from the historical to modern periods, within the modern period (the last 2 decades), and under future management and climate scenarios. We estimate that NPP of SAV and FAV during the historical period was approximately half that of today, before increases in open water and introduction of the highly productive water primrose. During the modern period (the last 20 years), high interannual variability in the extent and relative composition of aquatic vegetation species has driven significant variation in total NPP. This recent temporal variation is 6 to 13 times larger than projected changes in production from the potential future scenarios we modeled, including a reduction in FAV by 20% through control measures, substantial wetland restoration (and thus increased channel area that could support SAV and FAV), and increased salinity intrusion in the western Delta with climate warming, which favors native species with greater salinity tolerance. Large temporal swings in NPP of SAV and FAV cascade to influence the degree of carbon that flows to consumers through detrital pathways and herbivory. This volatility and interannual inconsistency in aquatic vegetation support of food webs make achieving wetland restoration goals for the Delta—which could lead to recovery of a portion of the NPP lost since historical times—even more imperative.
{"title":"Landscape Transformation and Variation in Invasive Species Abundance Drive Change in Primary Production of Aquatic Vegetation in the Sacramento–San Joaquin Delta","authors":"K. Boyer, Sam M. Safran, S. Khanna, Melissa V. Patten","doi":"10.15447/sfews.2023v20iss4art2","DOIUrl":"https://doi.org/10.15447/sfews.2023v20iss4art2","url":null,"abstract":"Conversion of wetlands in the Sacramento–San Joaquin Delta beginning in the mid-1800s resulted in a pronounced shift from a wetland-dominated food web to one driven by open-water primary producers. Submersed and floating aquatic vegetation (SAV and FAV) now rank highest in potential net primary production (NPP) among producer groups, and provide a comparable amount of carbon to the detrital food web as marshes. However, important details of this contribution that relate to shifts in species composition and habitat extent were not understood. Here, we review how changes in aquatic vegetation influence NPP and trophic support from the historical to modern periods, within the modern period (the last 2 decades), and under future management and climate scenarios. We estimate that NPP of SAV and FAV during the historical period was approximately half that of today, before increases in open water and introduction of the highly productive water primrose. During the modern period (the last 20 years), high interannual variability in the extent and relative composition of aquatic vegetation species has driven significant variation in total NPP. This recent temporal variation is 6 to 13 times larger than projected changes in production from the potential future scenarios we modeled, including a reduction in FAV by 20% through control measures, substantial wetland restoration (and thus increased channel area that could support SAV and FAV), and increased salinity intrusion in the western Delta with climate warming, which favors native species with greater salinity tolerance. Large temporal swings in NPP of SAV and FAV cascade to influence the degree of carbon that flows to consumers through detrital pathways and herbivory. This volatility and interannual inconsistency in aquatic vegetation support of food webs make achieving wetland restoration goals for the Delta—which could lead to recovery of a portion of the NPP lost since historical times—even more imperative.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47215340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-03DOI: 10.15447/sfews.2023v20iss4art5
E. Hestir, I. Dronova
Remote-sensing methods are being used to study a growing number of issues in the San Francisco Estuary, such as (1) detecting the optical properties of chlorophyll-a concentrations and dissolved organic matter to assess productivity and the nature of carbon inputs, (2) creating historical records of invasive aquatic vegetation expansion through space and time, (3) identifying origins and expansions of invasions, and (4) supporting models of greenhouse-gas sequestration by expanding restoration projects. Technological capabilities of remote sensing have likewise expanded to include a wide array of opportunities: from boat-mounted sensors, human-operated low-flying planes, and aerial drones, to freely accessible satellite imagery. Growing interest in coordinating these monitoring methods in the name of collaboration and cost-efficiency has led to the creation of diverse expert teams such as the Remote Imagery Collaborative, and monitoring frameworks such as the Interagency Ecological Program Aquatic Vegetation Monitoring Framework and Wetland Regional Monitoring Program. This paper explores the emerging technologies and applications of various methods for studying primary producers, with an emphasis on remote sensing.
{"title":"Remote Sensing of Primary Producers in the Bay-Delta","authors":"E. Hestir, I. Dronova","doi":"10.15447/sfews.2023v20iss4art5","DOIUrl":"https://doi.org/10.15447/sfews.2023v20iss4art5","url":null,"abstract":"Remote-sensing methods are being used to study a growing number of issues in the San Francisco Estuary, such as (1) detecting the optical properties of chlorophyll-a concentrations and dissolved organic matter to assess productivity and the nature of carbon inputs, (2) creating historical records of invasive aquatic vegetation expansion through space and time, (3) identifying origins and expansions of invasions, and (4) supporting models of greenhouse-gas sequestration by expanding restoration projects. Technological capabilities of remote sensing have likewise expanded to include a wide array of opportunities: from boat-mounted sensors, human-operated low-flying planes, and aerial drones, to freely accessible satellite imagery. Growing interest in coordinating these monitoring methods in the name of collaboration and cost-efficiency has led to the creation of diverse expert teams such as the Remote Imagery Collaborative, and monitoring frameworks such as the Interagency Ecological Program Aquatic Vegetation Monitoring Framework and Wetland Regional Monitoring Program. This paper explores the emerging technologies and applications of various methods for studying primary producers, with an emphasis on remote sensing.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42048440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-03DOI: 10.15447/sfews.2023v20iss4art4
J. L. Conrad, Madison Thomas, K. Jetter, J. Madsen, P. Pratt, P. Moran, J. Takekawa, G. Darin
Invasive aquatic vegetation (IAV) is a management challenge in the Sacramento–San Joaquin Delta and the Suisun Marsh that has commanded major resource investment for 4 decades. We review the history and supporting science of chemical, biological, and mechanical control of IAV in the Delta and Suisun March, and in flowing waters outside the region. Outside the Delta, there is a significant history of research on IAV control in lotic systems, but few studies come from tidal environments, and we found no investigations at a spatial scale like that of the Delta. The science of control efforts in the Delta is nascent but has seen marked growth over the recent decade. Since 1983, control of invasive submerged and floating species has been centralized within the California State Parks Division of Boating and Waterways (CDBW). The program relies on herbicides, with an annual budget that has exceeded $12.5 million since 2015. However, the results have been mixed because of the challenge of applying herbicides effectively in a tidal system. In parallel, biological control agents for water hyacinth (Eichhornia crassipes) and giant reed (Arundo donax) have been released but have not provided an appreciable control benefit, likely because they are not suited for the temperate Delta climate. Over recent decades, regulatory complexity has increased, hampering efforts to innovate alternative methods or respond quickly to new invaders. Control efforts for giant reed and common reed (Phragmites australis), the main invasive emergent plants, have not been coordinated under a central program, and studies to investigate control strategies have only recently been permitted. As a result, no local studies have been published on control outcomes for these species. Based on this history and our review of the science, we develop recommendations for leadership and science actions to proactively manage IAV.
{"title":"Invasive Aquatic Vegetation in the Sacramento–San Joaquin Delta and Suisun Marsh: The History and Science of Control Efforts and Recommendations for the Path Forward","authors":"J. L. Conrad, Madison Thomas, K. Jetter, J. Madsen, P. Pratt, P. Moran, J. Takekawa, G. Darin","doi":"10.15447/sfews.2023v20iss4art4","DOIUrl":"https://doi.org/10.15447/sfews.2023v20iss4art4","url":null,"abstract":"Invasive aquatic vegetation (IAV) is a management challenge in the Sacramento–San Joaquin Delta and the Suisun Marsh that has commanded major resource investment for 4 decades. We review the history and supporting science of chemical, biological, and mechanical control of IAV in the Delta and Suisun March, and in flowing waters outside the region. Outside the Delta, there is a significant history of research on IAV control in lotic systems, but few studies come from tidal environments, and we found no investigations at a spatial scale like that of the Delta. The science of control efforts in the Delta is nascent but has seen marked growth over the recent decade. Since 1983, control of invasive submerged and floating species has been centralized within the California State Parks Division of Boating and Waterways (CDBW). The program relies on herbicides, with an annual budget that has exceeded $12.5 million since 2015. However, the results have been mixed because of the challenge of applying herbicides effectively in a tidal system. In parallel, biological control agents for water hyacinth (Eichhornia crassipes) and giant reed (Arundo donax) have been released but have not provided an appreciable control benefit, likely because they are not suited for the temperate Delta climate. Over recent decades, regulatory complexity has increased, hampering efforts to innovate alternative methods or respond quickly to new invaders. Control efforts for giant reed and common reed (Phragmites australis), the main invasive emergent plants, have not been coordinated under a central program, and studies to investigate control strategies have only recently been permitted. As a result, no local studies have been published on control outcomes for these species. Based on this history and our review of the science, we develop recommendations for leadership and science actions to proactively manage IAV.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":"42 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41299467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-03DOI: 10.15447/sfews.2023v20iss4art1
L. Larsen, Samuel M. Bashevkin, Mairgareth Christman, J. L. Conrad, C. Dahm, Janet K. Thompson
The Sacramento–San Joaquin Delta (Delta) is a case-study of the Anthropocene “great accelerations,” with exponentially increasing temperatures and sea level over time, leading to rapid change in other ecosystem components. In nearly all these interconnected changes and across scales, primary producers play a major role, with diverse effects that mitigate or exacerbate rapid change induced by climate or other human-driven perturbations. Through this anthropocentric lens, primary producers can be viewed as performing numerous ecosystem services—which ultimately benefit humans—as well as ecosystem disservices, which have negative effects on human communities. For example, through carbon sequestration, wetlands can perform ecosystem services of mitigating warming at a global scale and combating relative sea-level rise at a local scale, while generating food that supports regional food webs and fisheries. On the other hand, invasive aquatic vegetation (IAV) can trap sediment before it reaches wetlands, exacerbating local subsidence and relative sea-level rise while incurring great costs to recreation, fishing, and agencies tasked with its control. Effectively managing these ecosystem services and disservices requires understanding of how they are connected. For example, wetland restoration often creates opportunities for IAV, which may inhibit sediment deposition on the wetland and outcompete native species. As the Delta science community works toward a more integrative understanding of how different components of the Delta interact as a whole and across scales, the pervasive effects of the ecosystem services and disservices of primary producers serve as foundational knowledge. In this topically themed edition of State of Bay-Delta Science, we review these effects. Individual chapters focus on the historical ecology of the primary productivity of aquatic vegetation, the ecology and control of invasive aquatic vegetation, harmful algal blooms, carbon sequestration and subsidence reversal by wetlands, and remote sensing methods for quantifying the ecosystem services and disservices of Delta primary producers.
{"title":"Ecosystem Services and Disservices of Bay-Delta Primary Producers: How Plants and Algae Affect Ecosystems and Respond to Management of the Estuary and Its Watershed","authors":"L. Larsen, Samuel M. Bashevkin, Mairgareth Christman, J. L. Conrad, C. Dahm, Janet K. Thompson","doi":"10.15447/sfews.2023v20iss4art1","DOIUrl":"https://doi.org/10.15447/sfews.2023v20iss4art1","url":null,"abstract":"The Sacramento–San Joaquin Delta (Delta) is a case-study of the Anthropocene “great accelerations,” with exponentially increasing temperatures and sea level over time, leading to rapid change in other ecosystem components. In nearly all these interconnected changes and across scales, primary producers play a major role, with diverse effects that mitigate or exacerbate rapid change induced by climate or other human-driven perturbations. Through this anthropocentric lens, primary producers can be viewed as performing numerous ecosystem services—which ultimately benefit humans—as well as ecosystem disservices, which have negative effects on human communities. For example, through carbon sequestration, wetlands can perform ecosystem services of mitigating warming at a global scale and combating relative sea-level rise at a local scale, while generating food that supports regional food webs and fisheries. On the other hand, invasive aquatic vegetation (IAV) can trap sediment before it reaches wetlands, exacerbating local subsidence and relative sea-level rise while incurring great costs to recreation, fishing, and agencies tasked with its control. Effectively managing these ecosystem services and disservices requires understanding of how they are connected. For example, wetland restoration often creates opportunities for IAV, which may inhibit sediment deposition on the wetland and outcompete native species. As the Delta science community works toward a more integrative understanding of how different components of the Delta interact as a whole and across scales, the pervasive effects of the ecosystem services and disservices of primary producers serve as foundational knowledge. In this topically themed edition of State of Bay-Delta Science, we review these effects. Individual chapters focus on the historical ecology of the primary productivity of aquatic vegetation, the ecology and control of invasive aquatic vegetation, harmful algal blooms, carbon sequestration and subsidence reversal by wetlands, and remote sensing methods for quantifying the ecosystem services and disservices of Delta primary producers.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42612677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-03DOI: 10.15447/sfews.2023v20iss4art3
Mairgareth Christman, S. Khanna, J. Drexler, M. Young
Substantial increases in non-native aquatic vegetation have occurred in the upper San Francisco Estuary over the last 2 decades, largely from the explosive growth of a few submerged and floating aquatic plant species. Some of these species act as ecosystem engineers by creating conditions that favor their further growth and expansion as well as by modifying habitat for other organisms. Over the last decade, numerous studies have investigated patterns of expansion and turn-over of aquatic vegetation species; effects of vegetation on ecosystem health, water quality, and habitat; and effects of particular species or communities on physical processes such as carbon and sediment dynamics. Taking a synthetic approach to evaluate what has been learned over the last few years has shed light on just how significant aquatic plant species and communities are to ecosystems in the Sacramento-San Joaquin Delta. Aquatic vegetation affects every aspect of the physical and biotic environment, acting as ecosystem engineers on the landscape. Furthermore, their effects are constantly changing across space and time, leaving many unanswered questions about the full effects of aquatic vegetation on Delta ecosystems and what future effects may result, as species shift in distribution and new species are introduced. Remaining knowledge gaps underlie our understanding of aquatic macrophyte effects on Delta ecosystems, including their roles and relationships with respect to nutrients and nutrient cycling, evapotranspiration and water budgets, carbon and sediment, and emerging effects on fish species and their habitats. This paper explores our current understanding of submerged and floating aquatic vegetation (SAV and FAV) ecology with respect to major aquatic plant communities, observed patterns of change, interactions between aquatic vegetation and the physical environment, and how these factors affect ecosystem services and disservices within the upper San Francisco Estuary.
{"title":"Ecology and Ecosystem Impacts of Submerged and Floating Aquatic Vegetation in the Sacramento–San Joaquin Delta","authors":"Mairgareth Christman, S. Khanna, J. Drexler, M. Young","doi":"10.15447/sfews.2023v20iss4art3","DOIUrl":"https://doi.org/10.15447/sfews.2023v20iss4art3","url":null,"abstract":"Substantial increases in non-native aquatic vegetation have occurred in the upper San Francisco Estuary over the last 2 decades, largely from the explosive growth of a few submerged and floating aquatic plant species. Some of these species act as ecosystem engineers by creating conditions that favor their further growth and expansion as well as by modifying habitat for other organisms. Over the last decade, numerous studies have investigated patterns of expansion and turn-over of aquatic vegetation species; effects of vegetation on ecosystem health, water quality, and habitat; and effects of particular species or communities on physical processes such as carbon and sediment dynamics. Taking a synthetic approach to evaluate what has been learned over the last few years has shed light on just how significant aquatic plant species and communities are to ecosystems in the Sacramento-San Joaquin Delta. Aquatic vegetation affects every aspect of the physical and biotic environment, acting as ecosystem engineers on the landscape. Furthermore, their effects are constantly changing across space and time, leaving many unanswered questions about the full effects of aquatic vegetation on Delta ecosystems and what future effects may result, as species shift in distribution and new species are introduced. Remaining knowledge gaps underlie our understanding of aquatic macrophyte effects on Delta ecosystems, including their roles and relationships with respect to nutrients and nutrient cycling, evapotranspiration and water budgets, carbon and sediment, and emerging effects on fish species and their habitats. This paper explores our current understanding of submerged and floating aquatic vegetation (SAV and FAV) ecology with respect to major aquatic plant communities, observed patterns of change, interactions between aquatic vegetation and the physical environment, and how these factors affect ecosystem services and disservices within the upper San Francisco Estuary.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49221729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-03DOI: 10.15447/sfews.2023v20iss4art6
R. Kudela, M. Howard, S. Monismith, H. Paerl
Harmful algal blooms (HABs) are on the rise worldwide. Known drivers for the proliferation and intensification of HAB events include increasing nutrient pollution, climate change, regulation and modification of hydrological flow, and the combined effect of climate drivers and nutrient pollution. The San Francisco Bay–Delta system has largely been immune to severe or acute HAB events, but there is both a potential and realized threat which has been underestimated and under-reported, in part because of the lack of coordinated sampling and data reporting. There is also increasing evidence that HABs must be considered in the context of a freshwater-to-marine continuum, and that the physical and political boundaries separating components of the Bay–Delta system are porous barriers to HABs and their toxins. Much remains to be learned about the ecology and physiology of HAB organisms in this system, but five primary environmental drivers can be identified: temperature, salinity, irradiance, nutrients, and stratification/residence time. All these drivers are responding rapidly to climate change, but nutrients are the primary variable that is largely under human control. Plans for the development of a comprehensive monitoring, prediction, and mitigation strategy across the freshwater-to-marine continuum have been documented; effectively following through on these plans provides a roadmap toward identifying the drivers and threats—and reducing the potential consequences now and in the future. While HABs alone are not a sufficient motivator for potentially costly and extensive mitigation efforts, there is strong evidence that decreasing nutrient loads, maintaining hydrological connectivity while minimizing stagnant regions, and managing the biota to maintain biodiversity of the Bay–Delta system will result in multiple co-benefits, including reduction of the HAB threat potential.
{"title":"Status, Trends, and Drivers of Harmful Algal Blooms Along the Freshwater-to-Marine Gradient in the San Francisco Bay–Delta System","authors":"R. Kudela, M. Howard, S. Monismith, H. Paerl","doi":"10.15447/sfews.2023v20iss4art6","DOIUrl":"https://doi.org/10.15447/sfews.2023v20iss4art6","url":null,"abstract":"Harmful algal blooms (HABs) are on the rise worldwide. Known drivers for the proliferation and intensification of HAB events include increasing nutrient pollution, climate change, regulation and modification of hydrological flow, and the combined effect of climate drivers and nutrient pollution. The San Francisco Bay–Delta system has largely been immune to severe or acute HAB events, but there is both a potential and realized threat which has been underestimated and under-reported, in part because of the lack of coordinated sampling and data reporting. There is also increasing evidence that HABs must be considered in the context of a freshwater-to-marine continuum, and that the physical and political boundaries separating components of the Bay–Delta system are porous barriers to HABs and their toxins. Much remains to be learned about the ecology and physiology of HAB organisms in this system, but five primary environmental drivers can be identified: temperature, salinity, irradiance, nutrients, and stratification/residence time. All these drivers are responding rapidly to climate change, but nutrients are the primary variable that is largely under human control. Plans for the development of a comprehensive monitoring, prediction, and mitigation strategy across the freshwater-to-marine continuum have been documented; effectively following through on these plans provides a roadmap toward identifying the drivers and threats—and reducing the potential consequences now and in the future. While HABs alone are not a sufficient motivator for potentially costly and extensive mitigation efforts, there is strong evidence that decreasing nutrient loads, maintaining hydrological connectivity while minimizing stagnant regions, and managing the biota to maintain biodiversity of the Bay–Delta system will result in multiple co-benefits, including reduction of the HAB threat potential.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48276226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-14DOI: 10.15447/sfews.2022v20iss3art1
R. Hartman, Arthur Barros, M. Avila, Christy Bowles, D. Ellis, Trishelle Tempel, S. Sherman
Wetland restoration is a key management tool for increasing food availability for at-risk fishes in the San Francisco Estuary. To characterize the benefits of restoration sites, it is critical to quantify the abundance and composition of fish food resources in and near the wetlands. Characterization of zooplankton communities is considered particularly important, but accurate analysis of zooplankton samples is time-consuming and expensive. The recently established Fish Restoration Program (FRP) Monitoring Team assessed whether data from existing long-term monitoring surveys could be used to characterize shallow-water zooplankton communities before restoration. During the springs of 2017 to 2019, the FRP collected zooplankton samples near the mouth of tidal wetland sites, or immediately outside future restoration sites, and compared them to concurrent samples collected in deep water by existing long-term monitoring surveys. We found very few differences in community composition between shallow and deep samples, though a few taxa were more abundant in shallow water. Seasonal and interannual differences in composition and abundance showed that restoration sites provide varying food resources over time. There was significantly higher total abundance of zooplankton in deep versus shallow water, which may be a result of differences in zooplankton production, migration, or fish predation. Inconsistencies in towing speed and gear type may also be driving this result, rather than true habitat differences. This study indicates that monitoring of wetland restoration sites must rely on multiple years of data collected on the site—rather than relying on adjacent open-water sampling—and should include monitoring of epiphytic and epibenthic invertebrates as well as zooplankton.
{"title":"I’m not that Shallow – Different Zooplankton Abundance but Similar Community Composition Between Habitats in the San Francisco Estuary","authors":"R. Hartman, Arthur Barros, M. Avila, Christy Bowles, D. Ellis, Trishelle Tempel, S. Sherman","doi":"10.15447/sfews.2022v20iss3art1","DOIUrl":"https://doi.org/10.15447/sfews.2022v20iss3art1","url":null,"abstract":"Wetland restoration is a key management tool for increasing food availability for at-risk fishes in the San Francisco Estuary. To characterize the benefits of restoration sites, it is critical to quantify the abundance and composition of fish food resources in and near the wetlands. Characterization of zooplankton communities is considered particularly important, but accurate analysis of zooplankton samples is time-consuming and expensive. The recently established Fish Restoration Program (FRP) Monitoring Team assessed whether data from existing long-term monitoring surveys could be used to characterize shallow-water zooplankton communities before restoration. During the springs of 2017 to 2019, the FRP collected zooplankton samples near the mouth of tidal wetland sites, or immediately outside future restoration sites, and compared them to concurrent samples collected in deep water by existing long-term monitoring surveys. We found very few differences in community composition between shallow and deep samples, though a few taxa were more abundant in shallow water. Seasonal and interannual differences in composition and abundance showed that restoration sites provide varying food resources over time. There was significantly higher total abundance of zooplankton in deep versus shallow water, which may be a result of differences in zooplankton production, migration, or fish predation. Inconsistencies in towing speed and gear type may also be driving this result, rather than true habitat differences. This study indicates that monitoring of wetland restoration sites must rely on multiple years of data collected on the site—rather than relying on adjacent open-water sampling—and should include monitoring of epiphytic and epibenthic invertebrates as well as zooplankton.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45255567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-14DOI: 10.15447/sfews.2022v20iss3art5
Samuel M. Bashevkin
Monitoring in the San Francisco Estuary (estuary) has fluctuated in sampling effort over time with changes to resources, objectives, and unforeseen events. I designed an approach to evaluate how reduced sampling would alter our ability to describe the status and trends of key species. This approach can evaluate the sensitivity of the estuary monitoring program to disruptions in sampling, and whether sampling effort could be reduced without compromising the information provided by these surveys. I simulated reduced sampling on top of the historical data record (1985–2018) by selectively removing data and evaluating the effect on model inference. The same model structure is fit to the full data set and several reduced data sets that represent simulations of reduced sampling effort. I then compared model predictions from reduced models to those from the full model to evaluate how reduced sampling may have affected our ability to detect key patterns in the data. In a case study, I applied this approach to Sacramento Splittail abundance trends from the Bay Study and the Suisun Marsh Fish Study otter trawls. Sampling reductions of 10% and 20% had fairly low impacts on the overlap of reduced model predictions with those from the full model. These results demonstrate the utility of my approach, but they are not generalizable beyond our ability to detect trends in Splittail abundance from Bay Study and Suisun Marsh Fish Study otter trawl data. A thorough analysis should run these simulations on multiple species and multiple parameters (e.g., abundance, distribution, length). By simulating sampling reductions on top of historical conditions, this approach could evaluate differential effects in varying environmental or historical conditions (e.g., droughts, species declines, invasions). In addition, this approach can easily be extended to other functional groups (e.g., zooplankton, phytoplankton) as well as physical parameters (e.g., temperature, salinity, Secchi depth).
{"title":"A Framework for Evaluating the Effects of Reduced Spatial or Temporal Monitoring Effort","authors":"Samuel M. Bashevkin","doi":"10.15447/sfews.2022v20iss3art5","DOIUrl":"https://doi.org/10.15447/sfews.2022v20iss3art5","url":null,"abstract":"Monitoring in the San Francisco Estuary (estuary) has fluctuated in sampling effort over time with changes to resources, objectives, and unforeseen events. I designed an approach to evaluate how reduced sampling would alter our ability to describe the status and trends of key species. This approach can evaluate the sensitivity of the estuary monitoring program to disruptions in sampling, and whether sampling effort could be reduced without compromising the information provided by these surveys. I simulated reduced sampling on top of the historical data record (1985–2018) by selectively removing data and evaluating the effect on model inference. The same model structure is fit to the full data set and several reduced data sets that represent simulations of reduced sampling effort. I then compared model predictions from reduced models to those from the full model to evaluate how reduced sampling may have affected our ability to detect key patterns in the data. In a case study, I applied this approach to Sacramento Splittail abundance trends from the Bay Study and the Suisun Marsh Fish Study otter trawls. Sampling reductions of 10% and 20% had fairly low impacts on the overlap of reduced model predictions with those from the full model. These results demonstrate the utility of my approach, but they are not generalizable beyond our ability to detect trends in Splittail abundance from Bay Study and Suisun Marsh Fish Study otter trawl data. A thorough analysis should run these simulations on multiple species and multiple parameters (e.g., abundance, distribution, length). By simulating sampling reductions on top of historical conditions, this approach could evaluate differential effects in varying environmental or historical conditions (e.g., droughts, species declines, invasions). In addition, this approach can easily be extended to other functional groups (e.g., zooplankton, phytoplankton) as well as physical parameters (e.g., temperature, salinity, Secchi depth).","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42809119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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