Karen Thorne, Ph.D.
Dr. Karen Thorne is a Research Ecologist with the USGS Western Ecological Research Center,
Her research focus is on climate change impacts to coastal ecosystems. In particular, her work has included assessing sea-level rise and storm impacts to coastal ecosystems, wetland ecology, restoration, and blue carbon. She received her Ph.D. and MS from the University of California, Davis.
Dr. Thorne's interests lie in conservation and management issues surrounding climate-related research that assess changes to ecosystems. Her current focus is assessing how sea-level rise and storms impact tidal wetland ecosystems in the U.S. and island habitats. She conducts research to inform climate adaptation and planning to help managers mitigate impacts and conduct restoration. Her research is based on field data collection methods that can be developed into climate change impact models using ArcGIS and other remote sensing tools.
RESEARCH INTERESTS
- Global Change Biology
- Coastal Ecosystems
- Wetland Ecology
- Restoration
- Threatened & Endangered Species
- Blue Carbon
- Landscape Ecology
- Ecological Response Modeling
- Storm Monitoring
- Sea-level Rise Planning & Decision Support
Professional Experience
Research Ecologist, USGS, Western Ecological Research Center, Davis Field Station, 2012 - present
Biologist, USGS, Western Ecological Research Center, San Francisco Bay Estuary Field Station, 2005 to 2012
Research Associate, U.S. Fish & Wildlife Service, Fairbanks, AK, 2002 to 2005
Education and Certifications
PhD, Geography, Global Change, University of California, Davis, 2012
MSc, Geography, Environmental Studies, University of California, Davis, 2008
BS, Wildlife, Fish, & Conservation Biology, University of California, Davis 2000
Affiliations and Memberships*
California Landscape Conservation Cooperative Science Team
Science and Products
Petaluma Marsh
Gambinini Marsh
Climate Extremes and Ecological Impacts to California Estuaries
Davis Field Station
Improving Our Ability to Forecast Tidal Marsh Response to Sea Level Rise
Understanding the Impacts of Ecological Drought on Estuaries in the Pacific Northwest
Effects of Sea-Level Rise and Extreme Storms on California Coastal Habitats: Part 2
Marshes to Mudflats: Climate Change Effects Along Coastal Estuaries in the Pacific Northwest
Effects of Sea-Level Rise and Extreme Storms on California Coastal Habitats: Part 1
Fate of Endangered Species in San Francisco Bay Tidal Marshes with Sea-Level Rise
Mangrove species’ response to sea-level rise across Pohnpei, Federated States of Micronesia
Seasonal impoundment alters patterns of tidal wetland plant diversity across spatial scales
Waterfowl use of wetland habitats informs wetland restoration designs for multi‐species benefits
Short-term impact of sediment addition on plants and invertebrates in a southern California salt marsh
Salinity and inundation effects on productivity of brackish tidal marsh plants in the San Francisco Bay-Delta Estuary
Testing the interactive effects of flooding and salinity on tidal marsh plant productivity
Spatiotemporal patterns of mineral and organic matter deposition across two San Francisco Bay-Delta tidal marshes
Effects of elevated sea levels and waves on southern California estuaries during the 2015–2016 El Niño
Habitat of the endangered salt marsh harvest mouse (Reithrodontomys raviventris) in San Francisco Bay
Understanding tidal marsh trajectories: Evaluation of multiple indicators of marsh persistence
Thin-layer sediment addition to an existing salt marsh to combat sea-level rise and improve endangered species habitat in California, USA
Flooding regimes increase avian predation on wildlife prey in tidal marsh ecosystems
Science and Products
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Petaluma Marsh
Petaluma marsh is located along the Petaluma River and covers 81 hectares. We surveyed 655 elevation points and 357 vegetation plots to determine baseline conditions of the marsh. Water level loggers deployed in 2010 were used to characterize the tidal inundation patterns throughout the year. Sediment accretion rates from soil cores were used as input for the WARMER sea-level rise response model...Gambinini Marsh
Gambinini marsh is located along the Petaluma River and covers 25 hectares. We surveyed 217 elevation points and 110 vegetation plots to determine baseline conditions of the marsh. Water level loggers deployed in 2010 were used to characterize the tidal inundation patterns throughout the year. Sediment accretion rates from soil cores at Petaluma marsh were extrapolated to Gambinini marsh and used...Climate Extremes and Ecological Impacts to California Estuaries
Estuaries are located at the interface where rivers meet the sea, creating unique ecosystems with complex physical and biological processes. Coastal wetlands provide essential ecosystem services to people, including flood protection from high tides and storm surges, commercial fisheries, carbon sequestration, improved water quality, and wildlife food and habitat. Coastal wetlands are also home toDavis Field Station
The Davis Field Station is home to research programs that focus on coastal ecosystem dynamics, ecological stressors, and their effects on wildlife populations. These studies primarily take place along the Pacific coast from the Aleutian Islands to southern California. Current projects investigate sea-level rise along both coasts of North America, landscape-scale aquatic and terrestrial ecology...Improving Our Ability to Forecast Tidal Marsh Response to Sea Level Rise
Our overall objective is to understand what controls the vulnerability of coastal marshes to risks associated with global change drivers and rising sea levels. Fundamental questions pertaining to coastal wetland vulnerability still need to be addressed. What factors explain spatial and geographic variation in tidal wetland vulnerability? How do short term climatic events (storms) influence the...Understanding the Impacts of Ecological Drought on Estuaries in the Pacific Northwest
In the Pacific Northwest, coastal ecosystems are highly productive areas that support millions of migratory waterbirds, shellfish, salmon and related fish. These species depend on food and habitats provided by estuaries (coastal tidal areas where streams and rivers flow into the ocean) for successful migration and breeding. Climate change effects such as drought, sea-level rise, and changing freshEffects of Sea-Level Rise and Extreme Storms on California Coastal Habitats: Part 2
In California, the near-shore area where the ocean meets the land is a highly productive yet sensitive region that supports a wealth of wildlife, including several native bird species. These saltmarshes, mudflats, and shallow bays are not only critical for wildlife, but they also provide economic and recreational benefits to local communities. Today, sea-level rise, more frequent and stronger storMarshes to Mudflats: Climate Change Effects Along Coastal Estuaries in the Pacific Northwest
Over 50% of commercial and recreationally important fish species depend on coastal wetlands. In the Pacific Northwest, coastal wetlands, where the ocean meets the land, are highly productive areas that support a wealth of wildlife species from salmon to ducks. The tidal marshes, mudflats, and shallow bays of coastal estuaries link marine, freshwater, and terrestrial habitats and provide economic aEffects of Sea-Level Rise and Extreme Storms on California Coastal Habitats: Part 1
In California, the near-shore area where the ocean meets the land is a highly productive yet sensitive region that supports a wealth of wildlife, including several native bird species. These saltmarshes, mudflats, and shallow bays are not only critical for wildlife, but they also provide economic and recreational benefits to local communities. Today, sea-level rise, more frequent and stronger storFate of Endangered Species in San Francisco Bay Tidal Marshes with Sea-Level Rise
The San Francisco Bay estuary contains the largest remaining expanse of tidal salt marshes in the western U.S. These marshes are home to a variety of federal and state protected species, such as the California clapper rail, California black rail, and the salt marsh harvest mouse. The estuary is also located on the Pacific Flyway, and is an important site for migrating and wintering birds. As clima - Data
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Mangrove species’ response to sea-level rise across Pohnpei, Federated States of Micronesia
Mangrove forests are likely vulnerable to accelerating sea-level rise; however, we lack the tools necessary to understand their future resilience. On the Pacific island of Pohnpei, Federated States of Micronesia, mangroves are habitat to endangered species and provide critical ecosystem services that support local communities. We developed a generalizable modeling framework for mangroves that accoAuthorsKevin J. Buffington, Richard A. MacKenzie, Joel A. Carr, Maybeleen Apwong, Ken W. Krauss, Karen M. ThorneSeasonal impoundment alters patterns of tidal wetland plant diversity across spatial scales
Understanding patterns of biodiversity is a key goal of ecology and is especially pressing in the current human‐caused biodiversity crisis. In wetland ecosystems, human impacts are centered around hydrologic manipulation including the common practice of wetland diking and impoundment. Constraining how wetland management influences plant biodiversity patterns across spatial scales will provide infoAuthorsScott Jones, Christopher N. Janousek, Michael L. Casazza, John Y. Takekawa, Karen M. ThorneWaterfowl use of wetland habitats informs wetland restoration designs for multi‐species benefits
Extensive global estuarine wetland losses have prompted intensive focus on restoration of these habitats. In California, substantial tracts of freshwater, brackish and tidal wetlands have been lost. Given the anthropogenic footprint of development and urbanization in this region, wetland restoration must rely on conversion of existing habitat types rather than adding new wetlands. These restoratioAuthorsMichael L. Casazza, Fiona McDuie, Scott Jones, Austen Lorenz, Cory T. Overton, Julie L. Yee, Cliff L. Feldheim, Josh T. Ackerman, Karen M. ThorneShort-term impact of sediment addition on plants and invertebrates in a southern California salt marsh
The implementation and monitoring of management strategies is integral to protect coastal marshes from increased inundation and submergence under sea-level rise. Sediment addition is one such strategy in which sediment is added to marshes to raise relative elevations, decrease tidal inundation, and enhance ecosystem processes. This study looked at the plant and invertebrate community responses oveAuthorsKaelin J McAtee, Karen M. Thorne, Christine R WhitcraftSalinity and inundation effects on productivity of brackish tidal marsh plants in the San Francisco Bay-Delta Estuary
Plant productivity is central to numerous ecosystem functions in tidal wetlands. We examined how productivity of brackish marsh plants in northern California responded to abiotic stress gradients of inundation and salinity using two experimental approaches. In a greenhouse study with varying salinity, shoot production and biomass of Juncus balticus, Schoenoplectus acutus and S. americanus all declAuthorsChristopher N. Janousek, Bruce D. Dugger, Brandon M Drucker, Karen M. ThorneTesting the interactive effects of flooding and salinity on tidal marsh plant productivity
Tidal wetlands support plant communities that facilitate carbon storage, accrete soil, and provide habitat for terrestrial and aquatic species. Climate change is likely to alter estuaries through sea-level rise and changing precipitation patterns, although the ecological responses are uncertain. We were interested in plant responses to physiological stress induced by elevated water salinity and flAuthorsKevin J. Buffington, Arianna C Goodman, Chase M. Freeman, Karen M. ThorneSpatiotemporal patterns of mineral and organic matter deposition across two San Francisco Bay-Delta tidal marshes
Sediment deposition in tidal wetlands is a critical process that determines whether vertical growth will keep pace with sea-level rise. However, more information is needed on how sediment deposition varies spatially and temporally across wetlands, including the effects of elevation, tidal inundation, vegetation, and weather. We investigated variation in sediment deposition due to season, distanceAuthorsKevin J. Buffington, Christopher N. Janousek, Karen M. Thorne, Bruce D. DuggerEffects of elevated sea levels and waves on southern California estuaries during the 2015–2016 El Niño
The 2015–2016 El Niño provided insight into how low-inflow estuaries might respond to future climate regimes, including high sea levels and more intense waves. High waves and water levels coupled with low rainfall along the Southern California coastline provided the opportunity to examine how extreme ocean forcing impacts estuaries independently from fluvial events. From November 2015 to April 201AuthorsMadeleine Harvey, Sarah N Giddings, Eric D. Stein, Jeffrey A Crooks, Christine R Whitcraft, Timu W. Gallien, John L. Largier, Liesl Tiefenthaler, Hallee Meltzer, Geno Pawlak, Karen M. Thorne, Karina Johnston, Richard F. Ambrose, Stephen C Schroeter, Henry M. Page, Hany ElwanyHabitat of the endangered salt marsh harvest mouse (Reithrodontomys raviventris) in San Francisco Bay
Understanding habitat associations is vital for conservation of at‐risk marsh‐endemic wildlife species, particularly those under threat from sea level rise. We modeled environmental and habitat associations of the marsh‐endemic, Federally endangered salt marsh harvest mouse (Reithrodontomys raviventris, RERA) and co‐occurrence with eight associated small mammal species from annual trap data, 1998–AuthorsBruce G. Marcot, Isa Woo, Karen M. Thorne, Chase M. Freeman, Glenn R. GuntenspergenUnderstanding tidal marsh trajectories: Evaluation of multiple indicators of marsh persistence
Robust assessments of ecosystem stability are critical for informing conservation and management decisions. Tidal marsh ecosystems provide vital services, yet are globally threatened by anthropogenic alterations to physical and biological processes. A variety of monitoring and modeling approaches have been undertaken to determine which tidal marshes are likely to persist into the future. Here, weAuthorsKerstin Wasson, Neil K. Ganju, Zafer Defne, Charlie Endris, Tracy Elsey-Quirk, Karen M. Thorne, Chase M. Freeman, Glenn R. Guntenspergen, Daniel J. Nowacki, Kenneth B. RaposaThin-layer sediment addition to an existing salt marsh to combat sea-level rise and improve endangered species habitat in California, USA
Current tidal marsh elevations and their accretion rates are important predictors of vulnerability to sea-level rise. When tidal marshes are at risk, adaptation measures, such as sediment addition to increase elevations, can be implemented to prevent degradation and loss. In 2016, wildlife managers prescribed a thin-layer sediment addition of locally sourced dredged material from Anaheim Bay to miAuthorsKaren M. Thorne, Chase M. Freeman, Jordan A. Rosencranz, Neil K. Ganju, Glenn R. GuntenspergenFlooding regimes increase avian predation on wildlife prey in tidal marsh ecosystems
Within isolated and fragmented populations, species interactions such as predation can cause shifts in community structure and demographics in tidal marsh ecosystems. It is critical to incorporate species interactions into our understanding when evaluating the effects of sea‐level rise and storm surges on tidal marshes. In this study, we hypothesize that avian predators will increase their presencAuthorsKaren M. Thorne, Kyle A. Spragens, Kevin J. Buffington, Jordan A. Rosencranz, John Takekawa - News
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government