David C Walters
David is a biological science tech with the Eastern Ecological Science Center at the Patuxent Research Refuge in Laurel, MD
David is a wetland ecologist, researching how coastal wetlands respond to sea level rise. With a background in biological and physical sciences, his work focuses on the interaction between wetland plant species and their physical environment.
Professional Experience
2020-Present - U.S. Geological Survey, Eastern Ecological Science Center, Biologist, Coastal Wetlands Group
2017-2020 - NSA Contractor with U.S. Geological Survey, Patuxent Wildlife Research Refuge, Coastal Wetlands Group
2013-2017 - Virginia Institute of Marine Science, Laboratory and Research Specialist
Education and Certifications
M.S., University of North Carolina- Chapel Hill, Geology (2013)
B.S., Longwood Univerity, Biology, concentration in Ecology (2011)
Science and Products
Filter Total Items: 83
Geographic drivers of mercury entry into aquatic food webs revealed by mercury stable isotopes in dragonfly larvae Geographic drivers of mercury entry into aquatic food webs revealed by mercury stable isotopes in dragonfly larvae
Atmospheric mercury (Hg) emissions and subsequent transport and deposition are major concerns within protected lands, including national parks, where Hg can bioaccumulate to levels detrimental to human and wildlife health. Despite this risk to biological resources, there is limited understanding of the relative importance of different Hg sources and delivery pathways within protected...
Authors
Sarah E. Janssen, Christopher James Kotalik, James Willacker, Michael T. Tate, Colleen M Flanagan-Pritz, Sarah Nelson, David P. Krabbenhoft, David Walters, Collin A. Eagles-Smith
PCB concentrations in riparian spiders (Tetragnathidae) consistently reflect concentrations in water and aquatic macroinvertebrates, but not sediment: Analysis of a seven-year field study PCB concentrations in riparian spiders (Tetragnathidae) consistently reflect concentrations in water and aquatic macroinvertebrates, but not sediment: Analysis of a seven-year field study
Tetragnathid spiders have been used as sentinels to study the biotransport of contaminants between aquatic and terrestrial environments because a significant proportion of their diet consists of adult aquatic insects. A key knowledge gap in assessing tetragnathid spiders as sentinels is understanding the consistency of the year-to-year relationship between contaminant concentrations in...
Authors
Ryan R. Otter, Marc A. Mills, Ken M. Fritz, James M. Lazorchak, Dalon P. White, Gale B. Beaubien, David Walters
Evolutionary and ecological correlates of thiaminase in fishes Evolutionary and ecological correlates of thiaminase in fishes
Thiamine (vitamin B1) is required by all living organisms in multiple metabolic pathways. It is scarce in natural systems, and deficiency can lead to reproductive failure, neurological issues, and death. One major cause of thiamine deficiency is an overreliance on diet items containing the enzyme thiaminase. Thiaminase activity has been noted in many prey fishes and linked to cohort...
Authors
Freya Elizabeth Rowland, Cathy A. Richter, Donald E Tillitt, David Walters
A novel approach to assessing natural resource injury with Bayesian networks A novel approach to assessing natural resource injury with Bayesian networks
Quantifying the effects of environmental stressors on natural resources is problematic because of complex interactions among environmental factors that influence endpoints of interest. This complexity, coupled with data limitations, propagates uncertainty that can make it difficult to causally associate specific environmental stressors with injury endpoints. The Natural Resource Damage...
Authors
Freya Elizabeth Rowland, Christopher James Kotalik, Bruce G. Marcot, Jo Ellen Hinck, David Walters
Mercury isotope values in shoreline spiders reveal transfer of aquatic mercury sources to terrestrial food webs Mercury isotope values in shoreline spiders reveal transfer of aquatic mercury sources to terrestrial food webs
The transfer of aquatic contaminants, including mercury (Hg), to terrestrial food webs is an often-overlooked exposure pathway to terrestrial animals. While research has implemented the use of shoreline spiders to assess aquatic to terrestrial Hg transfer, it is unclear whether Hg sources, estimated from isotope ratios, can be successfully resolved to inform site assessments and remedy
Authors
Sarah E. Janssen, Christopher James Kotalik, Collin A. Eagles-Smith, Gale B. Beaubien, Joel C. Hoffman, Greg Peterson, Marc A. Mills, David Walters
Identifying invertebrate indicators for streamflow duration assessments in forested headwater streams Identifying invertebrate indicators for streamflow duration assessments in forested headwater streams
Streamflow-duration assessment methods (SDAMs) are rapid, indicator-based tools for classifying streamflow duration (e.g., intermittent vs perennial flow) at the reach scale. Indicators are easily assessed stream properties used as surrogates of flow duration, which is too resource intensive to measure directly for many reaches. Invertebrates are commonly used as SDAM indicators because...
Authors
Ken M. Fritz, Roxolana O. Kashuba, Gregory J. Pond, Jay R. Christensen, Laurie C. Alexander, Benjamin J. Washington, Brent R. Johnson, David Walters, William T. Thoeny, Paul C. Weaver
Non-USGS Publications**
Lauzon, R., Murray, A. B., Moore, L. J., Walters, D. C., Kirwan, M. L., & Fagherazzi, S. (2018). Effects of marsh edge erosion in coupled barrier island-marsh systems and geometric constraints on marsh evolution. Journal of Geophysical Research: Earth Surface, 123, 1218– 1234. https://doi.org/10.1029/2017JF004530
Moore, L.J. et al. (2018). The Role of Ecomorphodynamic Feedbacks and Landscape Couplings in Influencing the Response of Barriers to Changing Climate. In: Moore, L., Murray, A. (eds) Barrier Dynamics and Response to Changing Climate. Springer, Cham. https://doi.org/10.1007/978-3-319-68086-6_10
Schieder, N.W., Walters, D.C. & Kirwan, M.L. Massive Upland to Wetland Conversion Compensated for Historical Marsh Loss in Chesapeake Bay, USA. Estuaries and Coasts 41, 940–951 (2018). https://doi.org/10.1007/s12237-017-0336-9
Walters, D.C. & M.L. Kirwan, Optimal hurricane overwash thickness for maximizing marsh resilience to sea level rise, Ecology and Evolution (2016). https://onlinelibrary.wiley.com/doi/10.1002/ece3.2024
Moore, L.J., Walters, D.C., et al., Ecomorphodynamic feedbacks and couplings between landscape units affect barrier island response to changing climate. In: Coastal Sediments, (2015). https://www.worldscientific.com/doi/10.1142/9789814689977_0246
Walters, D., et al., Interactions between barrier islands and backbarrier marshes affect island system response to sea level rise: Insights from a coupled model, Journal of Geophysical Research: Earth Surface, (2014). https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014JF003091
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 83
Geographic drivers of mercury entry into aquatic food webs revealed by mercury stable isotopes in dragonfly larvae Geographic drivers of mercury entry into aquatic food webs revealed by mercury stable isotopes in dragonfly larvae
Atmospheric mercury (Hg) emissions and subsequent transport and deposition are major concerns within protected lands, including national parks, where Hg can bioaccumulate to levels detrimental to human and wildlife health. Despite this risk to biological resources, there is limited understanding of the relative importance of different Hg sources and delivery pathways within protected...
Authors
Sarah E. Janssen, Christopher James Kotalik, James Willacker, Michael T. Tate, Colleen M Flanagan-Pritz, Sarah Nelson, David P. Krabbenhoft, David Walters, Collin A. Eagles-Smith
PCB concentrations in riparian spiders (Tetragnathidae) consistently reflect concentrations in water and aquatic macroinvertebrates, but not sediment: Analysis of a seven-year field study PCB concentrations in riparian spiders (Tetragnathidae) consistently reflect concentrations in water and aquatic macroinvertebrates, but not sediment: Analysis of a seven-year field study
Tetragnathid spiders have been used as sentinels to study the biotransport of contaminants between aquatic and terrestrial environments because a significant proportion of their diet consists of adult aquatic insects. A key knowledge gap in assessing tetragnathid spiders as sentinels is understanding the consistency of the year-to-year relationship between contaminant concentrations in...
Authors
Ryan R. Otter, Marc A. Mills, Ken M. Fritz, James M. Lazorchak, Dalon P. White, Gale B. Beaubien, David Walters
Evolutionary and ecological correlates of thiaminase in fishes Evolutionary and ecological correlates of thiaminase in fishes
Thiamine (vitamin B1) is required by all living organisms in multiple metabolic pathways. It is scarce in natural systems, and deficiency can lead to reproductive failure, neurological issues, and death. One major cause of thiamine deficiency is an overreliance on diet items containing the enzyme thiaminase. Thiaminase activity has been noted in many prey fishes and linked to cohort...
Authors
Freya Elizabeth Rowland, Cathy A. Richter, Donald E Tillitt, David Walters
A novel approach to assessing natural resource injury with Bayesian networks A novel approach to assessing natural resource injury with Bayesian networks
Quantifying the effects of environmental stressors on natural resources is problematic because of complex interactions among environmental factors that influence endpoints of interest. This complexity, coupled with data limitations, propagates uncertainty that can make it difficult to causally associate specific environmental stressors with injury endpoints. The Natural Resource Damage...
Authors
Freya Elizabeth Rowland, Christopher James Kotalik, Bruce G. Marcot, Jo Ellen Hinck, David Walters
Mercury isotope values in shoreline spiders reveal transfer of aquatic mercury sources to terrestrial food webs Mercury isotope values in shoreline spiders reveal transfer of aquatic mercury sources to terrestrial food webs
The transfer of aquatic contaminants, including mercury (Hg), to terrestrial food webs is an often-overlooked exposure pathway to terrestrial animals. While research has implemented the use of shoreline spiders to assess aquatic to terrestrial Hg transfer, it is unclear whether Hg sources, estimated from isotope ratios, can be successfully resolved to inform site assessments and remedy
Authors
Sarah E. Janssen, Christopher James Kotalik, Collin A. Eagles-Smith, Gale B. Beaubien, Joel C. Hoffman, Greg Peterson, Marc A. Mills, David Walters
Identifying invertebrate indicators for streamflow duration assessments in forested headwater streams Identifying invertebrate indicators for streamflow duration assessments in forested headwater streams
Streamflow-duration assessment methods (SDAMs) are rapid, indicator-based tools for classifying streamflow duration (e.g., intermittent vs perennial flow) at the reach scale. Indicators are easily assessed stream properties used as surrogates of flow duration, which is too resource intensive to measure directly for many reaches. Invertebrates are commonly used as SDAM indicators because...
Authors
Ken M. Fritz, Roxolana O. Kashuba, Gregory J. Pond, Jay R. Christensen, Laurie C. Alexander, Benjamin J. Washington, Brent R. Johnson, David Walters, William T. Thoeny, Paul C. Weaver
Non-USGS Publications**
Lauzon, R., Murray, A. B., Moore, L. J., Walters, D. C., Kirwan, M. L., & Fagherazzi, S. (2018). Effects of marsh edge erosion in coupled barrier island-marsh systems and geometric constraints on marsh evolution. Journal of Geophysical Research: Earth Surface, 123, 1218– 1234. https://doi.org/10.1029/2017JF004530
Moore, L.J. et al. (2018). The Role of Ecomorphodynamic Feedbacks and Landscape Couplings in Influencing the Response of Barriers to Changing Climate. In: Moore, L., Murray, A. (eds) Barrier Dynamics and Response to Changing Climate. Springer, Cham. https://doi.org/10.1007/978-3-319-68086-6_10
Schieder, N.W., Walters, D.C. & Kirwan, M.L. Massive Upland to Wetland Conversion Compensated for Historical Marsh Loss in Chesapeake Bay, USA. Estuaries and Coasts 41, 940–951 (2018). https://doi.org/10.1007/s12237-017-0336-9
Walters, D.C. & M.L. Kirwan, Optimal hurricane overwash thickness for maximizing marsh resilience to sea level rise, Ecology and Evolution (2016). https://onlinelibrary.wiley.com/doi/10.1002/ece3.2024
Moore, L.J., Walters, D.C., et al., Ecomorphodynamic feedbacks and couplings between landscape units affect barrier island response to changing climate. In: Coastal Sediments, (2015). https://www.worldscientific.com/doi/10.1142/9789814689977_0246
Walters, D., et al., Interactions between barrier islands and backbarrier marshes affect island system response to sea level rise: Insights from a coupled model, Journal of Geophysical Research: Earth Surface, (2014). https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014JF003091
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.