Source: UNIVERSITY OF CALIFORNIA, DAVIS submitted to
APPLIED FRESHWATER PREDATOR-PREY ECOLOGY.
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
REVISED
Funding Source
Reporting Frequency
Annual
Accession No.
0194909
Grant No.
(N/A)
Project No.
CA-D-ESP-7104-H
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2012
Project End Date
Sep 30, 2017
Grant Year
(N/A)
Project Director
Sih, A.
Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671
Performing Department
Environmental Science and Policy
Non Technical Summary
Predation often has major impacts on prey communities, populations and individual traits. Understanding predator-prey interactions is thus of great importance for many basic and applied environmental issues. In freshwater systems in California and throughout much of the world, introduced, exotic predators - notably, various fish and crayfish - are having a large and increasing effect on native communities. Introduced predators appear to have contributed to numerous declines and even extinctions of prey species. Understanding factors that influence the ability of exotic predators to invade and become abundant, and the relative impacts of these exotic predators on various prey are thus critical issues in applied predator-prey ecology. My laboratory addresses these issues using a combination of field surveys over large portions of the Sacramento delta, along with mechanistic studies of behavioral interactions between invasive predators and their prey, and through a blend of mathematical theory, literature review, field surveys, and field and laboratory experiments. Our work on the Brazilian waterweed and largemouth bass includes ongoing collaboration and interaction with relevant agency scientists. Our studies on signal crayfish are in collaboration with scientists that have direct influence on signal crayfish eradication efforts and on the Shasta crayfish recovery plan. In the past 5 years, the projects have provided training for 4 postdoctoral scientists (including 2 women), 7 PhD students (including 6 women, one African-American and one Native-American), and numerous undergraduates.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1350812107050%
1360899107050%
Goals / Objectives
Objective 1. Enhance our understanding of mechanisms underlying the success of non-native, nearshore fish in the Sacramento Delta. The primary focus of the project will be on effects of invasive Brazilian waterweed, Egeria densa, on the success of non-native largemouth bass. a. Quantify relationships between: (1) the biomass and species composition of submerged aquatic vegetation, (2) invertebrate biomass, diversity and community composition, (3) abundance, demography, growth, and gut fullness of various size-classes of largemouth bass, and (4) species diversity and relative abundances of native and non-native, shallow-water fish at numerous sites throughout the Sacramento delta. Objective 2. Enhance our understanding of behavioral mechanisms underlying the relative ability of different prey to persist with invasive signal crayfish and invasive mosquitofish. a. Quantify the behavioral responses of different prey (e.g., native versus introduced snails) to exotic, invasive predators. Test whether relative behavioral response explains relative ability of the prey to persist with exotic predators. b. For a widespread, common snail, and an invasive snail, quantify variation among populations in antipredator behavior and persistence with exotic predators. c. Conduct controlled laboratory experiments to examine sensory cues used by different prey to evaluate predation risk. Test whether variation in cue utilization explains the variation among prey in behavioral responses and thus ability to persist with predators. d. Develop new theoretical models to address how past predation regimes might explain current prey behavioral response to predators and, in turn, how these prey behaviors influence the ease of predator invasion and species interactions between invasive predators, their prey, their competitors and their own predators.
Project Methods
Objective 1. My laboratory has established > 30 field sites where we survey submerged aquatic vegetation (SAV), including the Brazilian waterweed, macroinvertebrates, and fish, along with data on basic abiotic variables (conductivity, turbidity, temperature). Fish are identified to species and measured (total length, weight). Larger largemouth bass are tagged and their stomach contents are sampled non-destructively. A number of smaller fish at each site are preserved for gut analyses and for otolith analyses of growth. Sophisticated multivariate analyses will be used to examine statistical relationships between abiotic variables, SAV biomass and species composition, invertebrate communities, fish communities, and in particular, largemouth bass abundances. Demographic models will be used to estimate fish growth, reproduction and size-dependent survival from time series of fish size distributions. Bioenergetic models will be used to relate invertebrates, fish diets and growth. Experiments in large mesocosm tanks will examine effects of SAV density on predator-prey interactions involving predatory adult largemouth bass, and vegetation-dwelling, open water and benthic prey including juvenile bass, sunfish, laboratory-reared delta smelt, and crayfish. Results have been and will continue to be disseminated regularly to relevant agency scientists and managers directly through ongoing collaboration, at regional conferences, and via reports and published papers. Objective 2. I will use laboratory experiments to contrast prey behavior (activity, refuge use, dispersal attempts) when exposed to free-ranging signal crayfish, free-ranging mosquitofish as well as to chemical cues known to elicit antipredator behavior (crayfish chemical cues, fish chemical cues, crushed prey, combinations of the three). I will also run these experiments with multiple populations of native, exotic/non-invasive (e.g. physid snails) and exotic/invasive (e.g., New Zealand mudsnails' NZMS) prey that differ in their history of exposure to crayfish, mosquitofish and other predators. The hypothesis is that the prey's history of exposure to particular types of predators will correlate with prey use of cues to detect risk, and with their ability to cope with crayfish, mosquitofish and other predators. Some trials have been completed with both physids and New Zealand mudsnails. I propose to expand this study to include more species, more populations and for Physa, more sibships within populations. In addition, I will expand my literature database on the role of evolutionary history with predators in explaining variation in prey behavioral response to introduced predators. I will develop new models to relate sensory mechanisms to behavior (e.g., using signal detection theory) and to contrast predator-prey dynamics involving co-evolved versus novel predator-prey interactions and the role of post-invasion co-evolution in governing invasion dynamics. Results will be disseminated to relevant agency scientists and managers at regional conferences and via published papers.

Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: My laboratory made progress on several fronts: 1) We completed the 4th year of a major study funded by the US Bureau of Reclamation (earlier funded by the California Department of Water Resources (DWR) in association with the Interagency Ecological Program (IEP)) in collaboration with Peter Moyle, Pete Klimley, and Susan Ustin's lab on how the recent spread of the Brazilian waterweed, Egeria densa, in the Sacramento Delta has influenced the distribution, abundance, growth and diets of non-native largemouth bass, an important predatory fish in nearshore waters. The study featured surveys of 33 sites throughout the south and central Delta every 2 months. Each survey includes electrofishing to document the numbers of all fish along standardized transects, collections of largemouth bass for stomach contents, and sampling to document Egeria abundance, along with basic abiotic measurements. The overall goal of the project is to understand how the increase in bass might be influencing the overall fish community (including the declining 'POD' species: Delta smelt, longfin smelt, threadfin shad, striped bass) and the Delta ecosystem. This project also included studies following movements of individual bass - working in collaboration with Dr. Pete Klimley, and mesocosm experiments examining how Egeria and water turbidity interact to influence bass predation rates. Progress reports on this work were presented at several regional conferences focused on the Bay-Delta ecosystem. The first paper on this work is now 'in press'. Several other manuscripts are in progress. 2) We also collaborated on a study funded by the US Bureau of Reclamation on the relative success of largemouth bass in 4 sites that differ in salinity. This work involved collaboration with Drs. Swee Teh and James Hobbes at UC/Davis and Fred Feyrer at USBR. We are currently processing fish samples: gut contents, physiological metrics, and otolith chemistry. 3) We continued work on the evolution of predator-prey behaviors that influence predator invasion dynamics. In particular, we focused on how individual variation in behavioral type affects foraging, survival with predators and dispersal in mosquitofish, and invasive pest, and on how variation in prey behavior influences their ability to cope with exotic predators. And, 4) We continued publishing previous work on how chemical stressors (pesticides, ocean acidification) influences behavior and fitness of aquatic organisms. We published 1 new paper with 2 others 'in press' on these topics, and gave invited talks on them at several universities as well as at international conferences. Details on publications are presented below. PARTICIPANTS: 1) The primary workers on the project on Egeria and largemouth bass are Dr. Louise Conrad, formerly a postdoctoral scientist in my laboratory, now a senior scientist at the Department of Water Resources, Kelly Weinersmith, a PhD student in my laboratory, 3 research technicians, Matthew Young, Denise DeCarion and Andrew Bibian, and Patrick Crain, a research scientist. As noted above, other collaborators include Peter Moyle, Pete Klimley. James Hobbes, Swee Teh, Fred Feyrer and Susan Ustin, a postdoc from Canada, Maud Ferrari, and several undergraduates. 2) The primary workers on the empirical work on effects of predator-prey behavior on predator invasion dynamics were Dr. Julien Cote, a postdoc, now a faculty member at U. Toulouse in France, Sean Fogarty, a PhD student in my lab, Tomas Brodin, a postdoc, now a faculty member at U. Umea/Sweden, and Kelly Weinersmith, a PhD student in my lab. Several undergraduates have also participated in this project. 3) The work on how chemical stressors affect antipredator behavior was done by Dr. Jake Kerby, a PhD student in my lab, now a faculty member at U. South Dakota, and by Dr. Maud Ferrari, a postdoc in my lab, now a faculty member at U. Saskatchewan (along with a team of international collaborators). TARGET AUDIENCES: 1) The audience for the project on Egeria and largemouth bass includes numerous agency scientists in regional state and federal agencies including, in particular, Ted Sommer, Anke Mueller-Solger, Fred Feyrer, Steve Culberson, and Larry Brown, as well as other stakeholders interested in policy and management of the Sacramento-Bay delta ecosystem. We reach this audience through frequent interaction at workshops and through reports and publications. 2) The audience for the project on behavior and invasions includes all scientists interested in understanding and managing predator invasions. We reach this audience through talks at universities, workshops and conferences, and through publications in international journals. 3) The audience for the project on chemical stressors and behavior includes all scientists interested in understanding and managing pesticide and ocean acidification effects on aquatic communities. We reach this audience through talks at universities, workshops and conferences, and through publications in international journals. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Our studies on invasive species provide important insights for anticipating and reducing their negative impacts of on aquatic communities. These insights should be useful for management and restoration. The study on predator-prey interactions involving largemouth bass and POD fish species includes contact and collaborations with numerous agency scientists that have a direct effect on management and policy related to the Bay-Delta Ecosystem including attempts to aid recovery for the POD species. More broadly, ideas from the work on predator-prey behavior and its potential influence on invasion dynamics is reaching an international audience via invited presentations at international conferences and at research universities around the world.

Publications

  • Ferrari, M.C.O., Ranaker, L., Weinersmith, K.L., Young, M.J., Sih, A. and Conrad, J.L. 2013. Effects of turbidity and invasive waterweed on predation by introduced largemouth bass. In press in Transactions of the American Fisheries Society.
  • Sih, A. 2013. Understanding variation in behavioural responses to human-induced rapid environmental change: a conceptual overview. Animal Behaviour, in press.
  • Ferrari, M.C.O., Manassa, R., Dixson, D.L., Munday, P.L., McCormick, M.I., Meekan, M.G., Sih, A. & Chivers, D.P. 2012. Effects of ocean acidification on learning in coral reef fishes PLoS ONE 7(2): e31478. doi:10.1371/journal.pone.0031478.
  • Cote, J., S. Fogarty and A. Sih. 2012. Individual sociability and choosiness between shoal types. Animal Behaviour 83:1469-1476.
  • Papers that were previous listed in press, but published in 2012 are: Kerby, J.L., Wehrmann, A. and A. Sih.2012. Impacts of the insecticide diazinon on the behavior of predatory fish and amphibian prey. Journal of Herpetology 46:171-176.
  • Ferrari, M.C.O., Dixson, D.L., Munday, P.L., McCormick, M.I., Meekan, M.G., Sih, A. & Chivers, D.P. 2011. Intrageneric variation in antipredator responses of coral reef fishes affected by ocean acidification: implications for climate change projections on marine communities. Global Change Biology 17: 2980-2986.


Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: My laboratory made progress on several fronts: 1) We completed the third year of a major study funded by the California Department of Water Resources (DWR) in association with the Interagency Ecological Program (IEP) and by the Bureau of Reclamation in collaboration with Peter Moyle, Pete Klimley, and Susan Ustin's lab on how the recent spread of the Brazilian waterweed, Egeria densa, in the Sacramento Delta has influenced the distribution, abundance, growth and diets of non-native largemouth bass, an important predatory fish in nearshore waters. This year, we completed our 2 year program of surveying 33 sites throughout the south and central Delta every 2 months. Each survey includes electrofishing to document the numbers of all fish along standardized transects, collections of largemouth bass for stomach contents, and sampling to document Egeria abundance, along with basic abiotic measurements. The overall goal of the project is to understand how the increase in bass might be influencing the overall fish community (including the declining 'POD' species: Delta smelt, longfin smelt, threadfin shad, striped bass) and the Delta ecosystem. This project also included studies following movements of individual bass - working in collaboration with Dr. Pete Klimley, and mesocosm experiments examining how Egeria and water turbidity interact to influence bass predation rates. Progress reports on this work were presented at several regional conferences focused on the Bay-Delta ecosystem. 2) We also continued to analyze data and published 2 papers on the ecology and behavior of two other important freshwater invasive pests in California: New Zealand mudsnails (NZMS), and signal crayfish. 3) We continued work on the evolution of predator-prey behaviors that influence predator invasion dynamics. In particular, we focused on how individual variation in behavioral type affects foraging, survival with predators and dispersal in mosquitofish, and invasive pest, and on how variation in prey behavior influences their ability to cope with exotic predators. And, 4) we continued work on how chemical stressors (pesticides or ocean acidification) influences antipredator behavior in amphibians and marine fish. We published 3 new papers on these topics, and gave invited talks on them at several universities (Stanford U.,Duke U., U. Kentucky, U. Wyoming, Simon Fraser U., UC/Berkeley, Michigan State U.) as well as at international conferences. Details on publications are presented below. PARTICIPANTS: 1) The primary workers on the project on Egeria and largemouth bass are Dr. Louise Conrad, formerly a postdoctoral scientist in my laboratory, now a senior scientist at the Department of Water Resources, Kelly Weinersmith, a PhD student in my laboratory, 3 research technicians, Matthew Young, Denise DeCarion and Andrew Bibian, and Patrick Crain, a research scientist. As noted above, other collaborators include Peter Moyle, Pete Klimley and Susan Ustin, graduate students in Susan Ustin's lab (Erin Hestir, Maria Santos), a postdoc from Canada, Maud Ferrari, and several undergraduates. 2) Impacts of introduced predators on aquatic prey. The primary person working on the NZMS component of this project is Valance Brenneis, who recently completed a PhD in my laboratory. A major part of the field work was done in Young's Bay in Oregon, a comparison to estuaries in California that have not yet been invaded by the NZMS. The work there collaborated with several scientists at Portland State University's Aquatic Bioinvasion Research and Policy Institute, and with teachers and students at the Applied Science Center at Astoria High School in Astoria, OR. The primary person working on signal crayfish is Lauren Pintor who recently completed her PhD and is now a postdoc at U. Illinois. Most of the work was done in northern California where signal crayfish are negatively impacting endangered Shasta crayfish. The work there collaborated with Jeff Cook and Maria Ellis, scientists who have a major influence on signal crayfish management as well as on the Shasta crayfish recovery plan. 3) The primary workers on the empirical work on effects of predator-prey behavior on predator invasion dynamics were Dr. Julien Cote, a postdoc, now a faculty member at U. Toulouse in France, Sean Fogarty, a PhD student in my lab, Tomas Brodin, a postdoc, now a faculty member at U. Umea/Sweden, and Kelly Smith, a PhD student in my lab. Several undergraduates have also participated in this project. 4) The work on how chemical stressors affect antipredator behavior was done by Dr. Jake Kerby, a PhD student in my lab, now a faculty member at U. South Dakota, and by Dr. Maud Ferrari, a postdoc in my lab, now a faculty member at U. Saskatchewan (along with a team of international collaborators). TARGET AUDIENCES: 1) The audience for the project on Egeria and largemouth bass includes numerous agency scientists in regional state and federal agencies including, in particular, Ted Sommer, Anke Mueller-Solger, Fred Feyrer, Steve Culberson, and Larry Brown, as well as other stakeholders interested in policy and management of the Sacramento-Bay delta ecosystem. We reach this audience through frequent interaction at workshops and through reports and publications. 2) The target audience for the projects NZMS and signal crayfish includes freshwater invasive species managers throughout the western U.S. We reach this audience through direct contact and publications. 3) The audience for the project on behavior and invasions includes all scientists interested in understanding and managing predator invasions. We reach this audience through talks at universities, workshops and conferences, and through publications in international journals. 4) The audience for the project on chemical stressors and behavior includes all scientists interested in understanding and managing pesticide and ocean acidification effects on aquatic communities. We reach this audience through talks at universities, workshops and conferences, and through publications in international journals. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Our studies on invasive species provide important insights for anticipating and reducing their negative impacts of on aquatic communities. These insights should be useful for management and restoration. The study on predator-prey interactions involving largemouth bass and POD fish species includes contact and collaborations with numerous agency scientists that have a direct effect on management and policy related to the Bay-Delta Ecosystem including attempts to aid recovery for the POD species. Our recently completed studies on signal crayfish are in collaboration with the scientists in northern California that have direct influence on the Shasta crayfish recovery plan. Work on the NZMS includes collaboration with a local agency scientist who has some influence on policy and with both university and agency scientists as well as high school teachers and students at the field site in Oregon. Finally, ideas from the work on predator-prey behavior and its potential influence on invasion dynamics is reaching an international audience via invited presentations at international conferences and at research universities around the world.

Publications

  • Kerby, J.L., Wehrmann, A. and A. Sih. 2012. Impacts of the insecticide diazinon on the behavior of predatory fish and amphibian prey. Journal of Herpetology, in press.
  • Ferrari, M.C.O., Dixson, D.L., Munday, P.L., McCormick, M.I., Meekan, M.G., Sih, A. & Chivers, D.P. 2011. Intrageneric variation in antipredator responses of coral reef fishes affected by ocean acidification: implications for climate change projections on marine communities. Global Change Biology 17: 2980-2986.
  • Ferrari, M.C.O., Manassa, R., Dixson, D.L., Munday, P.L., McCormick, M.I., Meekan, M.G., Sih, A. & Chivers, D.P. 2012. Effects of ocean acidification on learning in coral reef fishes PLoS ONE 7(2): e31478. doi:10.1371/journal.pone.0031478.


Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: My laboratory made progress on several fronts: 1) We completed the second year of a major study funded by the California Department of Water Resources (DWR) in association with the Interagency Ecological Program (IEP) and by the Bureau of Reclamation in collaboration with Peter Moyle, Pete Klimley, and Susan Ustin's lab on how the recent spread of the Brazilian waterweed, Egeria densa, in the Sacramento Delta has influenced the distribution, abundance, growth and diets of non-native largemouth bass, an important predatory fish in nearshore waters. This year, the project continued surveying 33 sites throughout the south and central Delta every 2 months. Each survey includes electrofishing to document the numbers of all fish along standardized transects, collections of largemouth bass for stomach contents, and sampling to document Egeria abundance, along with basic abiotic measurements. The overall goal of the project is to understand how the increase in bass might be influencing the overall fish community (including the declining 'POD' species: Delta smelt, longfin smelt, threadfin shad, striped bass) and the Delta ecosystem. This project also included studies following movements of individual bass - working in collaboration with Dr. Pete Klimley, and mesocosm experiments examining how Egeria and water turbidity interact to influence bass predation rates. Progress reports on this work were presented at several regional conferences focused on the Bay-Delta ecosystem. 2) We also continued to analyze data and published 2 papers on the ecology and behavior of two other important freshwater invasive pests in California: New Zealand mudsnails (NZMS), and signal crayfish. 3) We continued work on the evolution of predator-prey behaviors that influence predator invasion dynamics. In particular, we focused on how individual variation in behavioral type affects fish foraging, survival with predators and dispersal, and on how variation in prey behavior influences their ability to cope with exotic predators. We published 5 papers on these topics, and gave invited talks on them at several universities (Oxford U/UK, Florida State, U. Illinois, Arizona State, Michigan State) as well as at several international conferences. Details on publications are presented below. PARTICIPANTS: 1) The primary workers on the project on Egeria and largemouth bass are Dr. Louise Conrad, formerly a postdoctoral scientist in my laboratory, now a senior scientist at the Department of Water Resources, Kelly Smith, a PhD student in my laboratory, 3 research technicians, Matthew Young, Denise DeCarion and Andrew Bibian, and Patrick Crain, a research scientist. As noted above, other collaborators include Peter Moyle, Pete Klimley and Susan Ustin, graduate students in Susan Ustin's lab (Erin Hestir, Maria Santos), a postdoc from Canada, Maud Ferrari, and several undergraduates. 2) Impacts of introduced predators on aquatic prey. The primary person working on the NZMS component of this project is Valance Brenneis, who recently completed a PhD in my laboratory. A major part of the field work was done in Young's Bay in Oregon, a comparison to estuaries in California that have not yet been invaded by the NZMS. The work there collaborated with several scientists at Portland State University's Aquatic Bioinvasion Research and Policy Institute, and with teachers and students at the Applied Science Center at Astoria High School in Astoria, OR. The primary person working on signal crayfish is Lauren Pintor who recently completed her PhD and is now a postdoc at U. Illinois. Most of the work was done in northern California where signal crayfish are negatively impacting endangered Shasta crayfish. The work there collaborated with Jeff Cook and Maria Ellis, scientists who have a major influence on signal crayfish management as well as on the Shasta crayfish recovery plan. 3) The primary workers on the empirical work on effects of predator-prey behavior on predator invasion dynamics were Dr. Julien Cote, a postdoc from France, Sean Fogarty, a PhD student in my lab, Tomas Brodin, a postdoc from Sweden, and Kelly Smith, a PhD student in my lab. Several undergraduates have also participated in this project. The work on how prey behavioral responses to exotic predators might affect invasions, and in general, on variation in how organisms respond to novel environments was done with a postdoc, Maud Ferrari, and PhD student, David Harris, a research scientist at the University of Illinois, Richard Lankau and a Danish graduate student, Peter Jorgensen. TARGET AUDIENCES: 1) The audience for the project on Egeria and largemouth bass includes numerous agency scientists in regional state and federal agencies including, in particular, Ted Sommer, Anke Mueller-Solger, Fred Feyrer, Steve Culberson, and Larry Brown, as well as other stakeholders interested in policy and management of the Sacramento-Bay delta ecosystem. We reach this audience through frequent interaction at workshops and through reports and publications. 2) The target audience for the projects NZMS and signal crayfish includes freshwater invasive species managers throughout the western U.S. We reach this audience through direct contact and publications. 3) The audience for the project on behavior and invasions includes all scientists interested in understanding and managing predator invasions. We reach this audience through talks at universities, workshops and conferences, and through publications in international journals. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Our studies on invasive species provide important insights for anticipating and reducing their negative impacts of on aquatic communities. These insights should be useful for management and restoration. The study on predator-prey interactions involving largemouth bass and POD fish species includes contact and collaborations with the CALFED science team and numerous agency scientists that have a direct effect on management and policy related to the Bay-Delta Ecosystem including attempts to aid recovery for the POD species. Our recently completed studies on signal crayfish are in collaboration with the scientists in northern California that have direct influence on the Shasta crayfish recovery plan. Work on the NZMS includes collaboration with a local agency scientist who has some influence on policy and with both university and agency scientists as well as high school teachers and students at the field site in Oregon. Finally, ideas from the work on predator-prey behavior and its potential influence on invasion dynamics is reaching an international audience via invited presentations at international conferences and at research universities around the world.

Publications

  • Cote, J, S Fogarty, T Brodin, K Weinersmith and A Sih. Personality-dependent dispersal in the invasive mosquitofish: group composition matters. 2011. Proceedings of the Royal Society London, in press.
  • Fogarty, S, J Cote and A Sih. 2011. Social personality polymorphism and the spread of an invasive species: a model. American Naturalist, in press.
  • Brenneis, V and A. Sih. 2011. Integration of an invasive consumer into an estuarine food web: direct and indirect effects of the New Zealand mud snail. Oecologia, in press.
  • Pintor, LM and A Sih. 2011. Scale dependent effects of native prey diversity, prey biomass and natural disturbance on the invasion success of an exotic predator. Biological Invasions, in press.
  • Lankau, R., PS Jorgensen, DJ Harris and A Sih. 2011. Incorporating evolutionary principles into improved environmental management and policy. Evolutionary Applications, in press.
  • Sih, A, MCO Ferrari and DJ Harris. 2011. Evolution and behavioural responses to human-induced rapid environmental change. Evolutionary Applications, in press.
  • Conrad, JL, KL Weiner-Smith, T Brodin, JB Saltz and A. Sih. 2011. Behavioural syndromes in fishes: a review of the biology and implications for ecology and fisheries management. Journal of Fish Biology 78: 395-435.


Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: My laboratory made progress on several fronts: 1) We completed experiments and field surveys documenting effects of New Zealand mudsnails (NZMS) on other macroinvertebrates and on fish that feed on either NZMS or other macroinvertebrates. The PhD student working on this project, Val Brenneis, completed her PhD. The first paper on this work is in press. 2) We completed the first year of a major study funded by the California Department of Water Resources (DWR) in association with the Interagency Ecological Program (IEP) in collaboration with Peter Moyle, Pete Klimley, and Susan Ustin's lab on how the recent spread of the Brazilian waterweed, Egeria densa, in the Sacramento Delta has influenced the distribution, abundance, growth and diets of largemouth bass, an important predatory fish in nearshore waters. This year, the project surveyed 33 sites throughout the south and central Delta every 2 months. Each survey includes electrofishing to document the numbers of all fish along standardized transects, collections of largemouth bass for stomach contents, and sampling to document Egeria abundance, along with basic abiotic measurements. The overall goal of the project is to understand how the increase in bass might be influencing the overall fish community (including POD species: Delta smelt, longfin smelt, threadfin shad, striped bass) and the Delta ecosystem. This project also included studies following movements of individual bass - working in collaboration with Dr. Pete Klimley, and mesocosm experiments examining how Egeria and water turbidity interact to influence bass predation rates. 3) We also worked with an international team of ecologists and statisticians to analyze long-term data on the Delta to gain new insights on how multi-species interactions might influence long-term population dynamics of the POD species. This work yielded a multi-author paper in a top journal. Progress reports for projects 2 and 3 were presented at IEP workshops as well as at a joint workshop of the IEP with the National Center for Ecological Analysis and Synthesis. 4) We continued work on how predator-prey behavior influences predator invasion dynamics. In particular, we focused on how individual variation in behavioral type affects fish growth, survival with predators and dispersal. We published 3 papers on this topic, and gave invited talks on it at an Applied Evolution Summit to an international audience of evolutionary biologists and environmental managers, as well at several universities (Florida International University, University of California - San Diego, Lund University (Sweden), University of Nebraska, University of Toronto. Details on publications are presented below. PARTICIPANTS: 1) Impacts of introduced predators on aquatic prey. The primary person working on the NZMS component of this project is Valance Brenneis, who completed a PhD in 2009 in my laboratory. A major part of the field work was done in Young's Bay in Oregon, a comparison to estuaries in California that have not yet been invaded by the NZMS. The work there collaborated with several scientists at Portland State University's Aquatic Bioinvasion Research and Policy Institute, and with teachers and students at the Applied Science Center at Astoria High School in Astoria, OR. 2) The primary workers on the new project on Egeria on largemouth bass are Dr. Louise Conrad, a postdoctoral scientists, Kelly Smith, a PhD student in my laboratory, Matthew Young, a research technician, and Patrick Crain, a research scientist. As noted above, other collaborators include Peter Moyle, Pete Klimley and Susan Ustin, graduate students in Susan Ustin's lab (Erin Hestir, Maria Santos), a visiting PhD student from Sweden, Lynn Ranaker, a postdoc from Canada, Maud Ferrari, and several undergraduates. 3) The statistical analysis of long-term time series data in the Delta involves numerous collaborators that are members of a working group at the National Center for Ecological Analysis and Synthesis (NCEAS) in Santa Barbara, CA. 4) The primary workers on the empirical work on effects of predator-prey behavior on predator invasion dynamics were Dr. Julien Cote, a postdoc from France, Sean Fogarty, a PhD student in my lab, Tomas Brodin, a postdoc from Sweden, and Kelly Smith, a PhD student in my lab. Several undergraduates have also participated in this project. A literature and conceptual review that yielded new insights on how antipredator behavior influences predator invasions involved collaborations with a NCEAS working group (a different working group from the one noted in (3) above). TARGET AUDIENCES: 1) The target audience for project 1 on NZMS includes freshwater invasive species managers throughout the western U.S. We reach this audience through direct contact and publications. 2) The audience for projects 2 and 3 includes numerous agency scientists in the IEP, and CALFED including, in particular, Ted Sommer, Anke Mueller-Solger, Fred Feyrer, Steve Culberson, and Larry Brown, as well as other stakeholders interested in policy and management of the Sacramento-Bay delta ecosystem. We reach this audience through frequent interaction at workshops and through reports and publications. 3) The audience for project 4 includes all scientists interested in understanding and managing predator invasions. We reach this audience through talks at universities, workshops and conferences, and through publications in international journals. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Our studies on invasive species provide important insights for anticipating and reducing their negative impacts of on aquatic communities. These insights should be useful for management and restoration. Our recently completed studies on signal crayfish are in collaboration with the scientists in northern California that have direct influence on the Shasta crayfish recovery plan. Work on the NZMS includes collaboration with a local agency scientist who has some influence on policy, and with both university and agency scientists as well as high school teachers and students at the field site in Oregon. The study on predator-prey interactions involving largemouth bass and POD fish species includes contact and collaborations with the CALFED science team and numerous agency scientists that have a direct effect on management and policy related to the Bay-Delta Ecosystem including attempts to aid recovery for the POD species. The multivariate statistical analysis of long-term, Delta-wide trends in abundances of multiple species in the delta ecosystem involved collaboration with a team of aquatic ecologists, statisticians and modelers including relevant agency scientists and modelers from around the world. Results are being integrated directly into various delta ecosystem management discussions. Finally, ideas from the work on predator-prey behavior and its potential influence on invasion dynamics is reaching an international audience. One aspect - effects of individual variation in behavioral type on dispersal in invasive mosquitofish was featured as a Research Highlight in Nature, and in the on-line newsletter of the Society for Conservation Biology.

Publications

  • Conrad, J.L. and A. Sih. 2009. Behavioural type in newly emerged steelhead fry does not predict fitness in a conventional hatchery rearing environment. Journal of Fish Biology 75:1410-1426.
  • Sih, A., Bolnick, D.I., Luttbeg, B., Orrock, J.L., Peacor, S.D., Pintor, L.M., Preisser, E., Rehage, J. and Vonesh, J.R. 2010. Predator-prey naivete, antipredator behavior, and the ecology of predator invasions. Oikos, in press.
  • MacNally, R. Thomson, J.R., Kimmerer, W.J., Feyrer, F., Newman, K.B., Sih, A. Bennett, W.A., Brown, L., Fleishman, E., Culberson, S.D. and Castillo, G. 2010. An analysis of pelagic species decline in the upper San Francisco Estuary using Multivariate Autoregressive modelling (MAR). Ecological Applications, in press.
  • Cote, J. S. Fogarty, K. Weinersmith, T. Brodin and A. Sih. 2010. Behavioural syndromes and dispersal tendency in the invasive mosquitofish (Gambusia affinis). Proceedings Royal Society London B, in press.
  • Brenneis, VE, A. Sih and C.E. deRivera. 2010. Coexistence in the intertidal: Interactions between the non-indigenous New Zealand mud snail (Potamopyrgus antipodarum) and the native estuarine isopod (Gnorimosphaeroma insular). Oikos, in press.


Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: My laboratory made progress on several fronts: 1) We published 3 papers (1 published, 2 in press) reporting on work from the project on invasive signal crayfish. All three papers, in major journals in our field, describe how understanding signal crayfish behavior helps us to understand aspects of their invasion ecology. 2) We completed experiments and field surveys on the ecology of invasive New Zealand mudsnails (NZMS). New surveys and experiments documented effects of NZMS on other macroinvertebrates and on fish that feed on either NZMS or other macroinvertebrates. We are now in the process of preparing manuscripts for publication on these studies. 3) We completed additional analyses on experiments and field surveys on the joint use of space by predators and prey, and published a paper in a major journal in our field. At least two more papers are in preparation. 4) Perhaps most importantly, we garnered grant funds to add a new component to our overall project - studying effects of an invasive aquatic macrophyte on an introduced predatory fish, the largemouth bass, and in turn, how these bass influence the rest of the nearshore aquatic community in the Sacramento Delta. This study is described in more detail under Project Modifications. PARTICIPANTS: 1) Behavioral mechanisms underlying crayfish invasion success. Dr. Lauren Pintor recently completed a PhD in my laboratory working on this project. She is now a postdoctoral scientist at University of Illinois/Chicago. This project was done in collaboration with Dr. Maria Ellis and Dr. Jeffrey Cook from the Spring Rivers Ecological Sciences consulting firm. Drs. Ellis and Cook play a large role in the habitat restoration plan for the threatened Shasta crayfish which is endangered by competition from the invasive signal crayfish. We also served on the Spring Rivers Foundation's board of directors and thus interacted with other regional conservation scientists such as Ann Chrisney, a scientist for the Riparian Joint Habitat Venture. Finally, our GIS work was done with Dr. Josh Viers, a research assistant professor in DESP/UCDavis, and our laboratory assays were done with Brett Hanshew, a research assistant, and now a graduate student at Oregon State University 2) Impacts of introduced predators on aquatic prey. The primary person working on the NZMS component of this project is Valance Brenneis, a PhD student in my laboratory. Beverly Ajie, another PhD student in my laboratory, also worked on this project. A major part of the field work was done in Young's Bay in Oregon, a comparison to estuaries in California that have not yet been invaded by the NZMS. The work there collaborates with several scientists at Portland State University's Aquatic Bioinvasion Research and Policy Institute, and with teachers and students at the Applied Science Center at Astoria High School in Astoria, OR. 3) Joint habitat use of predators and prey. John Hammond recently completed a PhD working on this project. He is now a postdoc at the University of Pittsburgh. A research assistant professor on this project, Dr. Barney Luttbeg, recently moved to a tenure-track position at Oklahoma State University. Others contributing to experiments and data analyses are: Ryan Gilpin, an undergraduate researcher, Kelly Smith, a PhD student in my laboratory, and Dr. Tomas Brodin, a postdoctoral scientist from the Umea University, funded by the Swedish science council. 4) The primary workers on the new project (see Project Modifications) are Dr. Louise Conrad, a postdoctoral scientists, and Kelly Smith, a PhD student in my laboratory. As noted below, other collaborators include Peter Moyle, Pete Klimley and Susan Ustin, as well as graduate students in Susan Ustin's lab (Erin Hestir, Maria Santos). The statistical analysis of long-term time series data in the Delta involves numerous collaborators that are members of a working group at the National Center for Ecological Analysis and Synthesis (NCEAS) in Santa Barbara, CA. TARGET AUDIENCES: The Project Modification's audience includes numerous agency scientists in the IEP, and CALFED including, in particular, Ted Sommer, Anke Mueller-Solger, Fred Feyrer, and Larry Brown. PROJECT MODIFICATIONS: We made a major addition to our overall AES project. We garnered a grant from the California Department of Water Resources (DWR) in association with the Interagency Ecological Program (IEP) to conduct a major project (in collaboration with Peter Moyle and Susan Ustin's lab) on how the recent spread of the Brazilian waterweed, Egeria densa, in the Sacramento Delta has influenced the distribution, abundance, growth and diets of largemouth bass, an important predatory fish in nearshore waters. To date, the project has involved identifying 36 sites throughout the south and central Delta, and surveys every 2 months at each site. Each survey includes electrofishing to document the numbers of all fish along standardized transects, collections of largemouth bass for stomach contents, and sampling to document Egeria abundance, along with basic abiotic measurements. The overall goal of the project is to understand how the apparent increase in bass might be influencing the overall fish community (including POD species: Delta smelt, longfin smelt, threadfin shad, striped bass) and the Delta ecosystem. Later work will include: 1) following movements of individual bass - working in collaboration with Dr. Pete Klimley, and 2) mesocosm experiments on factors influencing bass predation rates. Finally, we are working with an international team of ecologists and statisticians to analyze long-term data on the Delta to gain new insights on how multi-species interactions might influence long-term population dynamics of the POD species.

Impacts
Our studies on invasive species provide important insights for anticipating and reducing their negative impacts of on aquatic communities. These insights should be useful for management and restoration. Our studies on signal crayfish are in collaboration with the scientists in northern California that have direct influence on the Shasta crayfish recovery plan. Three new papers are published or in press in major journals. One more paper should be submitted within the next few months. Work on the NZMS includes collaboration with a local agency scientist who has some influence on policy, and with both university and agency scientists as well as high school teachers and students at the field site in Oregon. The project on predator-prey space use yielded a publication in a major journal with at least 2 more likely to be submitted in the next few months. The new study (see Project Modifications) includes contact and collaborations with the CALFED science team and numerous agency scientists that have a direct effect on management and policy related to the Bay-Delta Ecosystem including attempts to aid recovery for the POD species.

Publications

  • Pintor, L.M., A. Sih and M.L. Bauer. 2008. Differences in aggression, activity and boldness between native and introduced populations of an invasive crayfish. Oikos 117:1629-1636.
  • Luttbeg, BT, JI Hammond and A. Sih. 2008. Dragonfly larvae and tadpole frog space use games in varied light conditions. Behavioral Ecology, in press.
  • Pintor, L.M. and A. Sih. 2008. Differences in growth and foraging behavior of native and introduced populations of an invasive crayfish. Biological Invasions, in press.
  • Pintor, L.M., A. Sih and J.L. Kerby. 2009. The effect of correlated behaviors and invader density on the impacts of an invasive crayfish. Ecology, in press.


Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: My laboratory made progress on several fronts. 1) We submitted 2 manuscripts describing earlier experiments comparing the effects of sublethal doses of several commonly used pesticides on predator-prey ecology involving California amphibian prey and predatory fish and aquatic insects. 2) We completed our experimental and field survey work on impacts of an invasive crayfish, the signal crayfish, on prey communities in northern California. We continued data analyses on prey community recovery following signal crayfish removal, and began GIS analyses examining the role of human behavior in human-aided dispersal of these invasive crayfish. 3) We continued to work on interactions involving invasive New Zealand mudsnails (NZMS) and their predators and competitors. New field work examined the ecology of the NZMS in estuaries in Oregon as a possible source of insight on the risk of NZMS invasion into California estuaries. 4) Funded by a NSF grant, we conducted field surveys and laboratory experiments on patterns of space use by aquatic predators and prey. PARTICIPANTS: Predator-prey ecotoxicology. Dr. Jacob Kerby completed a PhD in 2006 in my laboratory working on this projectg. We are in the process of publishing several papers from his PhD on this topic. Dr. Kerby is now a postdoctoral scientist at Washington State University Predator-prey ecology and signal crayfish invasions. Dr. Lauren Pintor completed a PhD in 2007 in my laboratory working on this project. She is now a postdoctoral scientist at University of Illinois/Chicago. This project was done in collaboration with Dr. Maria Ellis and Dr. Jeffrey Cook from the Spring Rivers Ecological Sciences consulting firm. Drs. Ellis and Cook play a large role in the habitat restoration plan for the threatened Shasta crayfish which is endangered by competition from the invasive signal crayfish. We also served on the Spring Rivers Foundation's board of directors and thus interacted with other regional conservation scientists such as Ann Chrisney, a scientist for the Riparian Joint Habitat Venture. Finally, our GIS work was done with Dr. Josh Viers, a research assistant professor in DESP/UCDavis, and our laboratory assays were done with Brett Hanshew, a research assistant, and now a graduate student at Oregon State University Predator-prey ecology and New Zealand mudsnail invasions. The primary person working on this project is Valance Brenneis, a PhD student in my laboratory. Beverly Ajie, another PhD student in my laboratory, also worked on this project. A major part of the field work was done in Young's Bay in Oregon, a comparison to estuaries in California that have not yet been invaded by the NZMS. The work there collaborates with several scientists at Portland State University's Aquatic Bioinvasion Research and Policy Institute, and with teachers and students at the Applied Science Center at Astoria High School in Astoria, OR. Predator-prey space use in California freshwater habitats. The primary people working on this project are John Hammond, a PhD student in my laboratory and Dr. Barney Luttbeg, a research assistant professor in DESP/UCDavis. Others contributing to experiments and data analyses are: Ryan Gilpin, an undergraduate researcher, Kelly Smith, a new PhD student in my laboratory, and Dr. Tomas Brodin, a postdoctoral scientist from the Umea University, funded by the Swedish science council.

Impacts
Our studies on pesticides and invasive species provide important insights for reducing negative impacts of human-induced stress on aquatic communities. These insights should be useful for management and restoration. Two new data papers on pesticides and predator-prey dynamics are in review at major journals. Our studies on signal crayfish are in collaboration with the scientists in northern California that have direct influence on the Shasta crayfish recovery plan. Two manuscripts are now in review. Additional data analyses should be completed within the next few months. Work on the NZMS includes collaboration with a local agency scientist who has some influence on policy, and with both university and agency scientists as well as high school teachers and students at the field site in Oregon. In addition, a general conceptual paper on predator-prey behavior and species invasions is in review as part of a Special Features collection of papers in Ecology. The 4th project (see above) yielded a published paper in Ecology, with 2 others now in review.

Publications

  • Hammond, JI, BT Luttbeg and A. Sih. Predator and prey space use: dragonflies and tadpoles in an interactive game. Ecology 88:1525-1535. 2007


Progress 01/01/06 to 12/31/06

Outputs
My laboratory made significant progress on four fronts. 1) We conducted experiments comparing the effects of sublethal doses of several commonly used pesticides on predator-prey ecology involving California amphibian prey and predatory fish and aquatic insects. New results examined effects of pesticides on how an exotic predator mediates competition between larval amphibians. 2) Funded by an extramural grant (from the National Sea Grant program), we continued our studies on impacts of an invasive crayfish, the signal crayfish, on prey communities in northern California. We continued data analyses on prey community recovery following signal crayfish removal, and conducted mesocosm experiments comparing the impacts of native versus invaded range crayfish on prey communities. Finally, we began examining the role of human behavior in human-aided dispersal of these invasive crayfish. 3) We continued to work on interactions involving invasive New Zealand mudsnails (NZMS) and their predators. New field work examined the ecology of the NZMS in estuaries in Oregon as a possible source of insight on the risk of NZMS invasion into California estuaries. 4) Funded by a NSF grant, we conducted field surveys and laboratory experiments on patterns of space use by aquatic predators and prey. We developed new statistical methods for analyzing these patterns.

Impacts
Our studies on pesticides and invasive species should provide important insights for reducing negative impacts of human-induced stress on aquatic communities. These insights should be useful for management and restoration. Our general ideas on effects of pesticides on aquatic predator-prey ecology were published in a recent paper in Trends in Ecology and Evolution. Several data papers on pesticides and predator-prey dynamics are in preparation and should be submitted within the next 6 months. Our studies on signal crayfish are in collaboration with the scientists in northern California that have direct influence on the Shasta crayfish recovery plan. Data analyses should be completed within the next few months. Work on the NZMS includes collaboration with a local agency scientist who has some influence on policy. The first manuscript from this work should be ready to submit for publication within the next 3 months. The 4th project (see above) yielded a paper that is 'in press' in Ecology. With regard to human impacts, these projects provided training for 1 postdoctoral scientist, 4 PhD students (including 3 women, one African-American), and 3 undergraduate researchers.

Publications

  • Rohr, J.R., J.L. Kerby and A. Sih. In Press, 2006Community ecology as a framework for predicting contaminant effects. Trends in Ecology and Evolution. Hammond, JI, BT Luttbeg and A. Sih. In Press 2006 Predator and prey space use: dragonflies and tadpoles in an interactive game. Ecology


Progress 01/01/05 to 12/31/05

Outputs
My laboratory made significant progress on four fronts. 1) We conducted experiments comparing the effects of sublethal doses of several commonly used pesticides on predator-prey ecology involving California amphibian prey and predatory fish and aquatic insects. New results examined effects of pesticides on competition among larval amphibians. 2) Funded by an extramural grant (from the National Sea Grant program), we continued field experiments on impacts of an invasive crayfish, the signal crayfish, on prey communities in northern California. We also continued data analyses on prey community recovery following signal crayfish removal, and conducted mesocosm experiments comparing the impacts of native versus invaded range crayfish on prey communities. 3) We continued to work on predator-prey interactions involving invasive New Zealand mudsnails and predatory signal crayfish. 4) Funded by a new NSF grant, we did field surveys and laboratory experiments on patterns of space use by predators and prey. We developed new statistical methods for analyzing these patterns.

Impacts
Our studies on pesticides and invasive species should provide important insights for reducing negative impacts of human-induced stress on aquatic communities. These insights should be useful for management and restoration. Although some of our preliminary results are now reaching the stage of being published, most of our ongoing studies have not yet been submitted for publication. Our work on effects of pesticides and herbicides on aquatic predator-prey ecology was presented at two national conferences in 2004. Our studies on signal crayfish are in collaboration with the scientists in northern California that have direct influence on the Shasta crayfish recovery plan. Given that most of this work has not yet reached mature fruition, the full impacts on management are yet to come. With regard to human impacts, these projects provided training 1 postdoctoral scientist, 4 PhD students (including 3 women, one African-American), and 8 undergraduate researchers (including 6 women and 1 male from an under-represented group).

Publications

  • Sih, A. 2005. Predator-prey space use as an emergent outcome of a behavioral response race. Pgs. 240-255 in The Ecology of Predator-Prey Interactions, edited by P. Barbosa and I. Castellanos. Oxford University Press.

    Rehage, J., B.K. Barnett and A. Sih. 2005. Foraging behavior and invasiveness: do invasive Gambusia exhibit higher feeding rates and broader diets than their non-invasive relatives? Ecology of Freshwater Fish 14:352-360.


Progress 01/01/04 to 12/31/04

Outputs
My laboratory made significant progress on four fronts. 1) We conducted experiments comparing the effects of sublethal doses of several commonly used pesticides on predator-prey ecology involving California amphibian prey and predatory fish and aquatic insects. New results showed one cannot generalize that one species is particularly susceptible or that one pesticide has a greater effect than others. Instead, impacts depended on the particular pesticide x species combination. The details of which species is hit harder by which pesticide have critical effects on how the pesticides affect species interactions. 2) We conducted parallel studies on effects of sublethal levels of an herbicide, atrazine, that is known to have endocrine disrupting effects on predator-prey interactions involving sunfish and salamander larvae. 3) Funded by an extramural grant (from the National Sea Grant program), we ran field experiments on impacts of an invasive crayfish, the signal crayfish, on prey communities in northern California. We also examined prey community recovery following signal crayfish removal, and compared the impacts of native versus invaded range crayfish on prey communities. 4) Finally, we began preliminary work on predator-prey interactions involving invasive New Zealand mudsnails and their predators. Invasive signal crayfish are effective predators on these invasive snails.

Impacts
Although some of our preliminary results are now reaching the stage of being published (see below), most of our ongoing studies have not yet been submitted for publication. Our work on effects of pesticides and herbicides on aquatic predator-prey ecology was presented at two national conferences in 2004. Our studies on signal crayfish are in collaboration with the scientists in northern California that have direct influence on the Shasta crayfish recovery plan. Given that most of this work has not yet reached mature fruition, the full impacts on management are yet to come. With regard to human impacts, these projects provided training 1 visiting postdoctoral associate, 3 PhD students (including 2 women, one African-American), and 5 undergraduate researchers (including 3 women and 1 male from an under-represented group).

Publications

  • Rohr, J.R., A.A. Elskus, B.S. Shepherd, P.H. Crowley, T.M. McCarthy, J.H. Niedzwiecki, A. Sih and B.D. Palmer. 2003. Lethal and sublethal effects of atrazine, carbaryl, endosulfan, and octylphenol on the streamside salamander, Ambystoma barbouri. Environmental Toxicology and Chemistry 22:2385-2392. in press at the time of the last year's progress report
  • Rehage, J.S. and A. Sih. 2004. Dispersal characteristics and boldness: a comparison of Gambusia species of varying invasiveness. Biological Invasions 6:379-391. in press at the time of the last year's progress report
  • Rohr, J.R., A.A. Elskus, B.S. Shepherd, P.H. Crowley, T.M. McCarthy, J.H. Niedzwiecki, T. Sager, A. Sih and B.D. Palmer. 2004. Multiple stressors and streamside salamanders: effects of the herbicide atrazine and food limitation. Ecological Applications 14:1028-1040. in press at the time of the last year's progress report
  • Sih, A., A.M. Bell and J.L. Kerby. 2004. Two stressors are far worse than one. Trends in Ecology and Evolution 19:274-276.
  • Sih, A., J. Kerby, A. Bell and R. Relyea. 2004. Response to Schmidt. Pesticides, mortality and population growth rate. Trends in Ecology and Evolution 19:480-481.
  • Rehage, J.S., Barnett, B. K. and A. Sih. 2004. Behavioral responses to novel predation and competition in invasive mosquitofish and their non-invasive relatives (Gambusia sp.). Behavioral Ecology and Sociobiology (in press).


Progress 01/01/03 to 12/31/03

Outputs
Progress: My laboratory made significant progress on four fronts. 1) We conducted experiments on the effects of sublethal doses of commonly used pesticides on predator-prey ecology involving California amphibian prey and predatory fish and aquatic insects. Results showed that depending on the relative susceptibility of the different species to a given pesticide, sublethal concentrations of a pesticide could either increase or decrease predation rates. 2) We conducted parallel studies on effects of sublethal levels of an herbicide, atrazine, that is known to have endocrine disrupting effects on predator-prey interactions involving sunfish and salamander larvae. 3) We garnered an extramural grant (from the National Sea Grant program) and began field experiments on impacts of an invasive crayfish, the signal crayfish, on prey communities in northern California. We also examined barriers to upstream movement for signal crayfish. These barriers are critical for keeping signal crayfish from invading stream stretches where they extirpate an endangered native crayfish, the Shasta crayfish. 4) We completed a study comparing important ecological traits of invasive versus non-invasive fishes in the genus Gambusia. Two of the species are listed among the 100 most important invasive species in the world. As expected, relative to non-invasive species, the invasive species have broader temperature tolerances, higher feeding rates, more effective antipredator responses, higher dispersal tendencies, and higher potential and realized population growth rates

Impacts
Impact: Although some of our preliminary results are now reaching the stage of being published (see below), most of our ongoing studies have not yet been submitted for publication. Our work on effects of pesticides and herbicides on aquatic predator-prey ecology was presented at two national conferences in 2003. Our studies on signal crayfish are in collaboration with the scientists in northern California that have direct influence on the Shasta crayfish recovery plan. Given that most of this work has not yet reached mature fruition, the full impacts on management are yet to come. With regard to human impacts, these projects provided training for 1 postdoctoral associate, 3 PhD students (including 2 women, one from an under-represented group), and 5 undergraduate researchers (including 3 women and 1 male from an under-represented group).

Publications

  • Rohr, J.R., A.A. Elskus, B.S. Shepherd, P.H. Crowley, T.M. McCarthy, J.H. Niedzwiecki, A. Sih and B.D. Palmer. 2003. Lethal and sublethal effects of atrazine, carbaryl, endosulfan, and octylphenol on the streamside salamander, Ambystoma barbouri. Environmental Toxicology and Chemistry (in press).
  • Rohr, J.R., A.A. Elskus, B.S. Shepherd, P.H. Crowley, T.M. McCarthy, J.H. Niedzwiecki, T. Sager, A. Sih and B.D. Palmer. 2003. Multiple stressors and streamside salamanders: Effects of the herbicide atrazine, food limitation, and drying conditions. Ecological Applications (in press).
  • Rehage, J.S. and A. Sih. 2003. Dispersal characteristics and boldness: a comparison of Gambusia species of varying invasiveness. Biological Invasions (in press).