Pub Date : 2020-03-09DOI: 10.15447/sfews.2020v18iss1art4
Dylan K. Stompe, Jason D. Roberts, Carlos Estrada, D. Keller, Nicholas M. Balfour, A. Banet
Author(s): Stompe, Dylan K.; Roberts, Jason D.; Estrada, Carlos A.; Keller, David M.; Balfour, Nicholas M.; Banet, Amanda I. | Abstract: This study examined diets of two predatory fish species, the native Sacramento Pikeminnow (Ptychocheilus grandis) and the introduced Striped Bass (Morone saxatilis), in the Sacramento River, California, USA. Both species have been implicated in native species declines through predation, eliciting our investigation of their diets in the Sacramento River. Sampling occurred between March and November 2017, and was conducted via hook and line on a 35-km reach near Chico, California. Habitat types sampled include engineered structures (water diversions and beam bridges), rip-rapped channel edges, and natural riverbank. Stomach contents were collected via gastric lavage and later processed using visual, gravimetric, and genetic techniques. Diets of Sacramento Pikeminnow and Striped Bass were highly similar as determined through index of relative importance and PERMANOVA modeling. Water temperature was the only variable that significantly affected diet composition. Results reflect similar dietary niches for both species in the Sacramento River.
{"title":"Sacramento River Predator Diet Analysis: A Comparative Study","authors":"Dylan K. Stompe, Jason D. Roberts, Carlos Estrada, D. Keller, Nicholas M. Balfour, A. Banet","doi":"10.15447/sfews.2020v18iss1art4","DOIUrl":"https://doi.org/10.15447/sfews.2020v18iss1art4","url":null,"abstract":"Author(s): Stompe, Dylan K.; Roberts, Jason D.; Estrada, Carlos A.; Keller, David M.; Balfour, Nicholas M.; Banet, Amanda I. | Abstract: This study examined diets of two predatory fish species, the native Sacramento Pikeminnow (Ptychocheilus grandis) and the introduced Striped Bass (Morone saxatilis), in the Sacramento River, California, USA. Both species have been implicated in native species declines through predation, eliciting our investigation of their diets in the Sacramento River. Sampling occurred between March and November 2017, and was conducted via hook and line on a 35-km reach near Chico, California. Habitat types sampled include engineered structures (water diversions and beam bridges), rip-rapped channel edges, and natural riverbank. Stomach contents were collected via gastric lavage and later processed using visual, gravimetric, and genetic techniques. Diets of Sacramento Pikeminnow and Striped Bass were highly similar as determined through index of relative importance and PERMANOVA modeling. Water temperature was the only variable that significantly affected diet composition. Results reflect similar dietary niches for both species in the Sacramento River.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15447/sfews.2020v18iss1art4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42808951","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 : 2020-03-09DOI: 10.15447/sfews.2020v18iss1art1
M. Nobriga, U. Fish, W. E. Smith
Author(s): Nobriga, Matthew L.; Smith, Wiliam E. | Abstract: Striped Bass, Morone saxatilis, has been an established member of the San Francisco Estuary’s (estuary’s) aquatic community for nearly a century and a half. As a predator, it has the potential to shape community composition through top-down control of lower trophic species, including the endangered Delta Smelt, Hypomesus transpacificus. Invasive predators can be particularly disruptive to native communities because they present novel dangers to naive populations, but, as a long-established member of the aquatic community, Striped Bass has not previously been considered to limit the Delta Smelt population. Here, we develop an argument that Striped Bass are important to controlling Delta Smelt. We support this argument by reviewing historical data which suggests that declines in Delta Smelt before the current-day monitoring program were driven by the invasion of Striped Bass into the estuary. We describe this phenomenon as the ‘phantom predator’ hypothesis in the context of an analog to the shifting baseline syndrome previously described for marine fisheries. A deeper understanding of how well studied (and rapidly changing) bottom-up drivers of the estuary food web interact with poorly understood (but also rapidly changing) controls at the top of the food web could prove very important to the conservation of other declining native fishes and possible future attempts to re-introduce captive-reared Delta Smelt to the estuary.
作者:Nobriga, Matthew L.;摘要:条纹鲈鱼(Morone saxatilis)是旧金山河口(河口)水生群落的一员，已有近一个半世纪的历史。作为一种捕食者，它有可能通过自上而下控制低营养物种来塑造群落组成，包括濒临灭绝的三角洲熔体，跨太平洋熔体。入侵的掠食者可能对当地社区造成特别的破坏，因为它们对原始种群构成了新的危险，但是，作为水生群落的长期成员，条纹鲈鱼以前没有被认为会限制三角洲鲑鱼的数量。在这里，我们提出一个论点，条纹鲈鱼是重要的控制三角洲冶炼。我们通过回顾历史数据来支持这一观点，这些数据表明，在目前的监测计划之前，三角洲冶炼厂的下降是由条纹鲈鱼入侵河口造成的。我们将这种现象描述为“幻影捕食者”假说，与之前描述的海洋渔业转移基线综合症类似。深入了解河口食物网的自下而上驱动因素是如何与食物网顶部鲜为人知(但也在迅速变化)的控制因素相互作用的，这对保护其他正在衰退的本地鱼类以及未来可能尝试将人工饲养的三角洲胡梅鱼重新引入河口非常重要。
{"title":"Did a Shifting Ecological Baseline Mask the Predatory Effect of Striped Bass on Delta Smelt?","authors":"M. Nobriga, U. Fish, W. E. Smith","doi":"10.15447/sfews.2020v18iss1art1","DOIUrl":"https://doi.org/10.15447/sfews.2020v18iss1art1","url":null,"abstract":"Author(s): Nobriga, Matthew L.; Smith, Wiliam E. | Abstract: Striped Bass, Morone saxatilis, has been an established member of the San Francisco Estuary’s (estuary’s) aquatic community for nearly a century and a half. As a predator, it has the potential to shape community composition through top-down control of lower trophic species, including the endangered Delta Smelt, Hypomesus transpacificus. Invasive predators can be particularly disruptive to native communities because they present novel dangers to naive populations, but, as a long-established member of the aquatic community, Striped Bass has not previously been considered to limit the Delta Smelt population. Here, we develop an argument that Striped Bass are important to controlling Delta Smelt. We support this argument by reviewing historical data which suggests that declines in Delta Smelt before the current-day monitoring program were driven by the invasion of Striped Bass into the estuary. We describe this phenomenon as the ‘phantom predator’ hypothesis in the context of an analog to the shifting baseline syndrome previously described for marine fisheries. A deeper understanding of how well studied (and rapidly changing) bottom-up drivers of the estuary food web interact with poorly understood (but also rapidly changing) controls at the top of the food web could prove very important to the conservation of other declining native fishes and possible future attempts to re-introduce captive-reared Delta Smelt to the estuary.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15447/sfews.2020v18iss1art1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44117955","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 : 2020-02-14DOI: 10.20944/preprints202002.0177.v1
V. Tobias
In fisheries monitoring, catch is assumed to be a product of fishing intensity, catchability, and availability, where availability is defined as the number or biomass of fish present and catchability refers to the relationship between catch rate and the true population. Ecological monitoring programs use catch per unit of effort (CPUE) to standardize catch and monitor changes in fish populations; however, CPUE is proportional to the portion of the population that is vulnerable to the type of gear that is used in sampling, which is not necessarily the entire population. Programs often deal with this problem by assuming that catchability is constant, but if catchability is not constant, it is not possible to separate the effects of catchability and population size using monitoring data alone. This study uses individual-based simulation to separate the effects of changing environmental conditions on catchability and availability in environmental monitoring data. The simulation combines a module for sampling conditions with a module for individual fish behavior to estimate the proportion of available fish that would escape from the sample. The method is applied to the case study of the well-monitored fish species Delta Smelt (Hypomesus transpacificus) in the San Francisco Estuary, where it has been hypothesized that changing water clarity may affect catchability for long-term monitoring studies. Results of this study indicate that given constraints on Delta Smelt swimming ability, it is unlikely that the apparent declines in Delta Smelt abundance are due to an effect of changing water clarity on catchability.
{"title":"Simulated Fishing to Untangle Catchability and Availability in Fish Abundance Monitoring","authors":"V. Tobias","doi":"10.20944/preprints202002.0177.v1","DOIUrl":"https://doi.org/10.20944/preprints202002.0177.v1","url":null,"abstract":"In fisheries monitoring, catch is assumed to be a product of fishing intensity, catchability, and availability, where availability is defined as the number or biomass of fish present and catchability refers to the relationship between catch rate and the true population. Ecological monitoring programs use catch per unit of effort (CPUE) to standardize catch and monitor changes in fish populations; however, CPUE is proportional to the portion of the population that is vulnerable to the type of gear that is used in sampling, which is not necessarily the entire population. Programs often deal with this problem by assuming that catchability is constant, but if catchability is not constant, it is not possible to separate the effects of catchability and population size using monitoring data alone. This study uses individual-based simulation to separate the effects of changing environmental conditions on catchability and availability in environmental monitoring data. The simulation combines a module for sampling conditions with a module for individual fish behavior to estimate the proportion of available fish that would escape from the sample. The method is applied to the case study of the well-monitored fish species Delta Smelt (Hypomesus transpacificus) in the San Francisco Estuary, where it has been hypothesized that changing water clarity may affect catchability for long-term monitoring studies. Results of this study indicate that given constraints on Delta Smelt swimming ability, it is unlikely that the apparent declines in Delta Smelt abundance are due to an effect of changing water clarity on catchability.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43247054","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 : 2019-12-08DOI: 10.15447/sfews.2019v17iss4art2
R. Connon, Simone Hasenbein, S. Brander, Helen C. Poynton, E. Holland, D. Schlenk, J. Orlando, M. Hladik, T. Collier, N. Scholz, J. Incardona, N. Denslow, A. Hamdoun, S. Nicklisch, N. Garcia-Reyero, E. Perkins, E. Gallagher, Xin Deng, Dan Wang, S. Fong, Richard S. Breuer, Mehrdad Hajibabei, James B. Brown, J. Colbourne, T. Young, G. Cherr, A. Whitehead, A. Todgham
Legacy and current-use contaminants enter into and accumulate throughout the San Francisco Bay−Delta (Bay−Delta), and are present at concentrations with known effects on species important to this diverse watershed. There remains major uncertainty and a lack of focused research able to address and provide understanding of effects across multiple biological scales, despite previous and ongoing emphasis on the need for it. These needs are challenging specifically because of the established regulatory programs that often monitor on a chemical-by-chemical basis, or in which decisions are grounded in lethality-based endpoints. To best address issues of contaminants in the Bay−Delta, monitoring efforts should consider effects of environmentally relevant mixtures and sub-lethal impacts that can affect ecosystem health. These efforts need to consider the complex environment in the Bay−Delta including variable abiotic (e.g., temperature, salinity) and biotic (e.g., pathogens) factors. This calls for controlled and focused research, and the development of a multi-disciplinary contaminant monitoring and assessment program that provides information across biological scales. Information gained in this manner will contribute toward evaluating parameters that could alleviate ecologically detrimental outcomes. This review is a result of a Special Symposium convened at the University of California−Davis (UCD) on January 31, 2017 to address critical information needed on how contaminants affect the Bay−Delta. The UCD Symposium focused on new tools and approaches for assessing multiple stressor effects to freshwater and estuarine systems. Our approach is similar to the recently proposed framework laid out by the U.S. Environmental Protection Agency (USEPA) that uses weight of evidence to scale toxicological responses to chemical contaminants in a laboratory, and to guide the conservation of priority species and habitats. As such, we also aimed to recommend multiple endpoints that could be used to promote a multi-disciplinary understanding of contaminant risks in Bay−Delta while supporting management needs.
{"title":"Review of and Recommendations for Monitoring Contaminants and their Effects in the San Francisco Bay−Delta","authors":"R. Connon, Simone Hasenbein, S. Brander, Helen C. Poynton, E. Holland, D. Schlenk, J. Orlando, M. Hladik, T. Collier, N. Scholz, J. Incardona, N. Denslow, A. Hamdoun, S. Nicklisch, N. Garcia-Reyero, E. Perkins, E. Gallagher, Xin Deng, Dan Wang, S. Fong, Richard S. Breuer, Mehrdad Hajibabei, James B. Brown, J. Colbourne, T. Young, G. Cherr, A. Whitehead, A. Todgham","doi":"10.15447/sfews.2019v17iss4art2","DOIUrl":"https://doi.org/10.15447/sfews.2019v17iss4art2","url":null,"abstract":"Legacy and current-use contaminants enter into and accumulate throughout the San Francisco Bay−Delta (Bay−Delta), and are present at concentrations with known effects on species important to this diverse watershed. There remains major uncertainty and a lack of focused research able to address and provide understanding of effects across multiple biological scales, despite previous and ongoing emphasis on the need for it. These needs are challenging specifically because of the established regulatory programs that often monitor on a chemical-by-chemical basis, or in which decisions are grounded in lethality-based endpoints. To best address issues of contaminants in the Bay−Delta, monitoring efforts should consider effects of environmentally relevant mixtures and sub-lethal impacts that can affect ecosystem health. These efforts need to consider the complex environment in the Bay−Delta including variable abiotic (e.g., temperature, salinity) and biotic (e.g., pathogens) factors. This calls for controlled and focused research, and the development of a multi-disciplinary contaminant monitoring and assessment program that provides information across biological scales. Information gained in this manner will contribute toward evaluating parameters that could alleviate ecologically detrimental outcomes. This review is a result of a Special Symposium convened at the University of California−Davis (UCD) on January 31, 2017 to address critical information needed on how contaminants affect the Bay−Delta. The UCD Symposium focused on new tools and approaches for assessing multiple stressor effects to freshwater and estuarine systems. Our approach is similar to the recently proposed framework laid out by the U.S. Environmental Protection Agency (USEPA) that uses weight of evidence to scale toxicological responses to chemical contaminants in a laboratory, and to guide the conservation of priority species and habitats. As such, we also aimed to recommend multiple endpoints that could be used to promote a multi-disciplinary understanding of contaminant risks in Bay−Delta while supporting management needs.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15447/sfews.2019v17iss4art2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42701788","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 : 2019-12-08DOI: 10.15447/sfews.2019v17iss4art1
S. Luoma, L. Muscatine
Author(s): Luoma, Samuel N.; Muscatine, Lauren D. | Abstract: Sixteen years ago, in October 2003, San Francisco Estuary and Watershed Science (SFEWS) published its first article. An anniversary like this is a good time to remind ourselves of our history, and to ask if the journal is living up to the goals we set in 2003. And if so, are those goals consistent with today’s needs? In 2004, CDL’s eScholarship Publishing Group counted an average of 254 requests per month for SFEWS online articles. In 2010, that increased to 1,232 requests per month, and in 2014 to 1,764 per month. In the first 10 months of 2019, 4,420 articles were requested per month. Downloads have been consistently 35% to 40% of requests. Taking data from 2014 through 2017, the search engine Scopus’ CiteScore for SFEWS increased from 0.32 to 1.64; its rank is 82nd of 203 journals in the Water Science and Technology category for 2018, a remarkable climb from being ranked 120 of 179 in 2014. SFEWS is ranked fifth among 53 open access journals in the aquatic sciences, according to the Science Journal Ranking index; and in the top 25% among all 218 aquatic science journals ranked by that index. Thus, SFEWS has grown from an outlet designed to expand access to regional science to a well-respected scientific journal in its own right. Our look back shows that SFEWS has probably grown beyond our original expectations in size, influence, and stature.
{"title":"Sixteen Years of San Francisco Estuary and Watershed Science: A Retrospective","authors":"S. Luoma, L. Muscatine","doi":"10.15447/sfews.2019v17iss4art1","DOIUrl":"https://doi.org/10.15447/sfews.2019v17iss4art1","url":null,"abstract":"Author(s): Luoma, Samuel N.; Muscatine, Lauren D. | Abstract: Sixteen years ago, in October 2003, San Francisco Estuary and Watershed Science (SFEWS) published its first article. An anniversary like this is a good time to remind ourselves of our history, and to ask if the journal is living up to the goals we set in 2003. And if so, are those goals consistent with today’s needs? In 2004, CDL’s eScholarship Publishing Group counted an average of 254 requests per month for SFEWS online articles. In 2010, that increased to 1,232 requests per month, and in 2014 to 1,764 per month. In the first 10 months of 2019, 4,420 articles were requested per month. Downloads have been consistently 35% to 40% of requests. Taking data from 2014 through 2017, the search engine Scopus’ CiteScore for SFEWS increased from 0.32 to 1.64; its rank is 82nd of 203 journals in the Water Science and Technology category for 2018, a remarkable climb from being ranked 120 of 179 in 2014. SFEWS is ranked fifth among 53 open access journals in the aquatic sciences, according to the Science Journal Ranking index; and in the top 25% among all 218 aquatic science journals ranked by that index. Thus, SFEWS has grown from an outlet designed to expand access to regional science to a well-respected scientific journal in its own right. Our look back shows that SFEWS has probably grown beyond our original expectations in size, influence, and stature.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15447/sfews.2019v17iss4art1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45372348","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 : 2019-12-08DOI: 10.15447/sfews.2019v17iss4art3
Brendan Lehman, Meagan Gary, Nicholas J. Demetras, C. Michel
The Sacramento–San Joaquin Delta has been invaded by several species of non-native predatory fish that are presumed to be impeding native fish population recovery efforts. Since eradication of predators is unlikely, there is substantial interest in removing or altering manmade structures in the Delta that may exacerbate predation on native fish (contact points). It is presumed that these physical structures influence predator-prey dynamics, but how habitat features influence species interactions is poorly understood, and physical structures in the Delta that could be remediated to benefit native fish have not been inventoried completely. To inform future research efforts, we reviewed literature that focused on determining the effects of predator-prey interactions between fish, based on contact points that are commonly found in the Delta. We also performed a geospatial analysis to determine the extent of potential contact points in the Delta. We found that the effects of submerged aquatic vegetation (SAV) and artificial illumination are well studied and documented to influence predation in other freshwater systems worldwide. Conversely, other common structures in the Delta—such as docks, pilings, woody debris, revetment, and water diversions—did not have the same breadth of research. In the Delta, the spatial extent of the different types of contact points differed considerably. For example, 22% of the Delta water surface area is occupied by SAV, whereas docks only cover 0.44%. Our conclusion, based on both the literature review and spatial analysis, is that the effects of SAV and artificial illumination on predation warrant the most immediate future investigation in the Delta.
{"title":"Where Predators and Prey Meet: Anthropogenic Contact Points Between Fishes in a Freshwater Estuary","authors":"Brendan Lehman, Meagan Gary, Nicholas J. Demetras, C. Michel","doi":"10.15447/sfews.2019v17iss4art3","DOIUrl":"https://doi.org/10.15447/sfews.2019v17iss4art3","url":null,"abstract":"The Sacramento–San Joaquin Delta has been invaded by several species of non-native predatory fish that are presumed to be impeding native fish population recovery efforts. Since eradication of predators is unlikely, there is substantial interest in removing or altering manmade structures in the Delta that may exacerbate predation on native fish (contact points). It is presumed that these physical structures influence predator-prey dynamics, but how habitat features influence species interactions is poorly understood, and physical structures in the Delta that could be remediated to benefit native fish have not been inventoried completely. To inform future research efforts, we reviewed literature that focused on determining the effects of predator-prey interactions between fish, based on contact points that are commonly found in the Delta. We also performed a geospatial analysis to determine the extent of potential contact points in the Delta. We found that the effects of submerged aquatic vegetation (SAV) and artificial illumination are well studied and documented to influence predation in other freshwater systems worldwide. Conversely, other common structures in the Delta—such as docks, pilings, woody debris, revetment, and water diversions—did not have the same breadth of research. In the Delta, the spatial extent of the different types of contact points differed considerably. For example, 22% of the Delta water surface area is occupied by SAV, whereas docks only cover 0.44%. Our conclusion, based on both the literature review and spatial analysis, is that the effects of SAV and artificial illumination on predation warrant the most immediate future investigation in the Delta.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15447/sfews.2019v17iss4art3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41535339","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 : 2019-12-08DOI: 10.15447/sfews.2019v17iss4art4
W. E. Smith
A Bayesian hierarchical model that integrated information about state and observation processes was used to estimate the number of adult Delta Smelt entrained into the southern Sacramento−San Joaquin Delta during water export operations by the California State Water Project and the Central Valley Project. The model hierarchy accounted for dynamic processes of transport, survival, sampling efficiency, and observation. Water export, mark−recapture, and fish facility count data informed each process. Model diagnostics and simulation testing indicated a good fit of the model, and that parameters were jointly estimable in the Bayesian hierarchical model framework. The model was limited, however, by sparse data to estimate survival and State Water Project sampling efficiency. Total December to March entrainment of adult Delta Smelt ranged from an estimated 142,488 fish in 2000 to 53 fish in 2014, and the efficiency of louvers used to divert entrained fish to fish facilities appeared to decline at high and low primary intake channel velocities. Though applied to Delta Smelt, the hierarchical modeling framework was sufficiently flexible to estimate the entrainment of other pelagic species.
{"title":"Integration of Transport, Survival, and Sampling Efficiency in a Model of South Delta Entrainment","authors":"W. E. Smith","doi":"10.15447/sfews.2019v17iss4art4","DOIUrl":"https://doi.org/10.15447/sfews.2019v17iss4art4","url":null,"abstract":"A Bayesian hierarchical model that integrated information about state and observation processes was used to estimate the number of adult Delta Smelt entrained into the southern Sacramento−San Joaquin Delta during water export operations by the California State Water Project and the Central Valley Project. The model hierarchy accounted for dynamic processes of transport, survival, sampling efficiency, and observation. Water export, mark−recapture, and fish facility count data informed each process. Model diagnostics and simulation testing indicated a good fit of the model, and that parameters were jointly estimable in the Bayesian hierarchical model framework. The model was limited, however, by sparse data to estimate survival and State Water Project sampling efficiency. Total December to March entrainment of adult Delta Smelt ranged from an estimated 142,488 fish in 2000 to 53 fish in 2014, and the efficiency of louvers used to divert entrained fish to fish facilities appeared to decline at high and low primary intake channel velocities. Though applied to Delta Smelt, the hierarchical modeling framework was sufficiently flexible to estimate the entrainment of other pelagic species.","PeriodicalId":38364,"journal":{"name":"San Francisco Estuary and Watershed Science","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15447/sfews.2019v17iss4art4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43717778","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 : 2019-09-19DOI: 10.15447/sfews.2019v17iss3art1
P. Bachand, T. Kraus, W. Horwath, Nathan R. Hatch, S. Bachand
Author(s): Bachand, Philip A. M.; Kraus, Tamara E. C.; Horwarth, William R.; Hatch, Nathan R.; Bachand, Sandra M. | Abstract: Water quality impairment and land surface subsidence threaten the viability of the Sacramento–San Joaquin Delta (Delta), a critical component of California’s water conveyance system. Current-day irrigation drainage through Delta island peat soils affects drinking water treatment and is linked to mercury transport, potentially posing both ecological and public health concerns. To cost-effectively treat agricultural drainage water from subsided Delta islands to reduce the export of drinking Water Quality Constituents of Concern and mitigate land subsidence through accretion, we studied hybrid coagulation-treatment wetland systems, termed Chemically Enhanced Treatment Wetlands (CETWs). We provide cost estimates and design recommendations to aid broader implementation of this technology. Over a 20-year horizon using a Total Annualized Cost analysis, we estimate treatment costs of $602 to $747 per acre-foot (ac‑ft) water treated, and $36 to $70 per kg dissolved organic carbon (DOC) removed, depending upon source water DOC concentrations for a small 3-acre CETW system. For larger CETW systems scaled for island sizes of 3,500 to 14,000 acres, costs decrease to $108 to $239 per ac-ft water treated, and $11 to $14 per kg DOC removed. We estimated the footprints of CETW systems to be approximately 3% of the area being treated for 4-day hydraulic retention time (HRT) systems, but they would decrease to less than 1% for 1-day HRT systems. CETWs ultimately address several of the Delta’s key internal issues while keeping water treatment costs competitive with other currently available treatment technologies at similar scales on a per-carbon-removed basis. CETWs offer a reliable system to reduce out-going DOC and mercury loads, and they provide the additional benefit of sediment accretion. System costs and treatment efficacy depend significantly on inflow source water conditions, land availability, and other practical matters. To keep costs low and removal efficacy high, wetland design features will need site-specific evaluation.
作者:Bachand, Philip a.m.;克劳斯，塔玛拉·e·c;威廉·霍沃斯;Nathan R. Hatch;摘要:作为加州输水系统的重要组成部分，萨克拉门托-圣华金三角洲(Delta)的水质恶化和地表沉降威胁着其生存能力。目前通过三角洲泥炭土进行的灌溉排水影响饮用水处理，并与汞运输有关，可能造成生态和公共健康问题。为了经济有效地处理三角洲下沉岛屿的农业排水，以减少饮用水质量成分的出口，并通过增加减少地面沉降，我们研究了混合混凝处理湿地系统，称为化学强化处理湿地(CETWs)。我们提供成本估算和设计建议，以帮助更广泛地实现该技术。在20年的时间跨度内，使用总年化成本分析，我们估计每英亩英尺(ac - ft)水处理成本为602美元至747美元，每公斤溶解有机碳(DOC)去除成本为36美元至70美元，具体取决于3英亩小型CETW系统的源水DOC浓度。对于面积为3500 - 14000英亩的大型污水处理系统，处理水的成本降至每平方英尺108 - 239美元，去除每公斤DOC的成本降至11 - 14美元。我们估计，在4天的水力滞留时间(HRT)系统中，CETW系统的占地面积约为处理面积的3%，而在1天的HRT系统中，这一面积将减少到不到1%。CETWs最终解决了三角洲地区的几个关键内部问题，同时在每碳去除量的基础上，使水处理成本与其他类似规模的现有处理技术相比具有竞争力。CETWs提供了一个可靠的系统来减少外排DOC和汞负荷，并且它们还提供了沉积物增加的额外好处。系统成本和处理效果在很大程度上取决于流入水源的水条件、土地可用性和其他实际问题。为了保持低成本和高去除效果，湿地设计特征需要根据具体地点进行评估。
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Pub Date : 2019-09-19DOI: 10.15447/sfews.2019v17iss3art5
T. Sloey, M. Hester
Author(s): Sloey, Taylor M.; Hester, Mark W. | Abstract: Liberty Island, California, is a historical freshwater tidal wetland that was converted to agricultural fields in the early 1900s. Liberty Island functioned as farmland until an accidental levee break flooded the area in 1997, inadvertently restoring tidal marsh hydrology. Since then, wetland vegetation has naturally recolonized part of the site. We conducted a seed bank assay at the site and found that despite a lack of germination or seedling recruitment at the site, the seed bank contained a diverse plant community, indicating that the site’s continuous flooding was likely suppressing germination. Additionally, the frequency of germinating seeds in the seed bank did not represent the dominant adult plant community. We conducted a cold stratification study to determine if this observed disparity could be explained by seed germination dynamics, and whether germination could be enhanced using a pre-germination cold exposure, particularly for species of concern for wetland restoration. The cold stratification study showed that longer durations of pre-germination cold enhanced germination in Schoenoplectus acutus, but reduced germination in Schoenoplectus californicus, and had no effect on Typha latifolia. Overall, germination of S. californicus and S. acutus was much lower than T. latifolia. Our findings suggest that seeding may not be an effective restoration technique for Schoenoplectus spp., and, to improve restoration techniques, further study is needed to more comprehensively understand the reproduction ecology of important marsh species.
作者:Sloey, Taylor M.;摘要:美国加州自由岛是一个历史悠久的淡水潮汐湿地，在20世纪初被改造为农田。自由岛原本是农田，直到1997年意外决堤淹没了该地区，无意中恢复了潮汐沼泽的水文。从那时起，湿地植被自然地重新定居在该遗址的一部分。我们在该地点进行了种子库分析，发现尽管该地点缺乏发芽或幼苗招募，但种子库中包含了多样化的植物群落，这表明该地点的持续洪水可能抑制了发芽。此外，种子库中萌发种子的频率并不能代表优势成虫群落。我们进行了一项冷分层研究，以确定这种观察到的差异是否可以用种子萌发动力学来解释，以及种子萌发前的冷暴露是否可以促进萌发，特别是对于湿地恢复关注的物种。冷分层研究表明，较长的萌发前冷处理时间能促进尖穗雪蚤的萌发，但会降低加州雪蚤的萌发，而对热带风叶没有影响。总体而言，加州葡萄球菌和尖头葡萄球菌的萌发率远低于大叶葡萄球菌。我们的研究结果表明，播种可能不是一种有效的恢复技术，为了改进恢复技术，需要进一步研究更全面地了解重要沼泽物种的繁殖生态。
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Pub Date : 2019-09-19DOI: 10.15447/sfews.2019v17iss3art3
D. Weston, Christoph Moschet, T. Young, Nadhirah Johanif, Helen C. Poynton, Kaley M. Major, R. Connon, Simone Hasenbein
Author(s): Weston, Donald P.; Moschet, Christoph; Young, Thomas M.; Johanif, Nadhirah; Poynton, Helen C.; Major, Kaley M.; Connon, Richard E.; Hasenbein, Simone | Abstract: Chemical and toxicological testing in the Cache Slough complex (the slough) of the North Delta indicated the aquatic biota are exposed to a variety of wastewater-derived food additives, pharmaceuticals, and personal care products in highest concentration during dry periods, and many insecticides, herbicides and fungicides with peak concentrations after winter rains. The insecticide groups currently known to be of greatest toxicological concern are the pyrethroids and the fiproles (i.e., fipronil and its degradation products). After stormwater runoff enters the system via Ulatis Creek, both pesticide groups attained concentrations that posed a threat to aquatic life. When the commonly used testing species, Hyalella azteca, was placed in Cache Slough, toxicity — and, at times, near total mortality — was seen over at least an 8-km reach of Cache Slough that extended from the uppermost end almost to the junction with the Deep Water Ship Channel. Previous work over many years has shown similar results after other winter storms. However, when H. azteca that carried a mutation providing resistance to pyrethroid pesticides were also deployed in the slough, no ill effects were observed, which provided strong evidence that pyrethroids were responsible for toxicity to the non-resistant strain. Abundant resident H. azteca in Cache Slough carry any of four mutations that provide resistance to pyrethroids. They also carry a mutation that provides resistance to organophosphate pesticides, and likely carbamate pesticides as well. After many years of exposure, sensitive genotypes have been nearly eliminated from the system, and replaced by a population unaffected by many insecticides now in common use. We offer a variety of reasons why this shift to a population with mutant genotypes is of considerable concern, but also note that society has yet to fully consider the ecological and regulatory ramifications of the evolutionary attainment of pollutant resistance.
作者:Weston, Donald P.;Moschet Christoph;托马斯·m·杨;Johanif Nadhirah;海伦·c·波因顿;少校，凯莉·M.;Richard E. Connon;摘要北三角洲Cache Slough complex (Slough)的化学和毒理学测试表明，水生生物群在干旱期暴露于各种废水衍生的食品添加剂、药品和个人护理用品中，其浓度最高，而在冬雨期暴露于多种杀虫剂、除草剂和杀菌剂中，其浓度最高。目前已知最令人关切的毒理学杀虫剂类别是拟除虫菊酯和氟虫腈(即氟虫腈及其降解产物)。雨水经乌拉提斯河进入系统后，两种农药的浓度都达到了对水生生物构成威胁的程度。当常用的测试物种阿兹特克透明藻被放置在Cache Slough中时，从Cache Slough的最上端几乎延伸到深水船舶通道的交汇处，至少8公里范围内的毒性-有时几乎是完全死亡-被观察到。此前多年的研究也显示了其他冬季风暴后的类似结果。然而，当携带对拟除虫菊酯杀虫剂产生抗性的突变的阿兹特克蚜也被放置在秸秆中时，没有观察到任何不良影响，这提供了强有力的证据，证明拟除虫菊酯是对非抗性菌株产生毒性的原因。在Cache Slough中大量居住的H. azteca携带对拟除虫菊酯具有抗性的四种突变中的任何一种。它们还携带了一种突变，可以抵抗有机磷农药，也可能对氨基甲酸酯类农药产生抗性。经过多年的接触，敏感基因型几乎已经从系统中消失，取而代之的是不受目前常用的许多杀虫剂影响的种群。我们提供了各种原因，为什么这种转变与突变基因型的人群是相当关注的，但也注意到，社会尚未充分考虑到生态和调控的进化实现污染物抗性的后果。
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