Kevin Kroeger has studied coastal ecosystems since 1990, with focus on a range of topics including fluxes and biogeochemistry of nitrogen in groundwater discharge to estuaries and wetlands, estuarine water quality, and carbon and greenhouse gas cycling and fluxes in coastal wetlands.
Kroeger is lead of the Biogeochemical Processes group at Woods Hole Coastal and Marine Science Center, and lead of a new project titled: Biogeochemical Drivers of Wetland Persistence and Feedbacks on Coastal Hazards The objectives of this Project are to provide guidance to federal (National Park Service, Fish & Wildlife Service, Army Corp of Engineers), state, local and private land owners and managers regarding stability and persistence of coastal wetlands under a range of hydrological management conditions and changing environmental conditions. Tidal wetlands provide critical services to society, including protection of infrastructure from coastal hazards, and habitat provision for economically important species. A large fraction of U.S. tidal wetlands, however, has been lost or degraded during recent centuries due to human actions, largely related to development and utilization of coastal lands. Feedbacks and interactions among natural and anthropogenic drivers have altered the stability and persistence of coastal wetlands. Decisions regarding hydrological management can alter the balance of organic matter production, retention and preservation, and thus management actions can either promote wetland persistence and resilience, or cause catastrophic loss of elevation, putting coastal infrastructure at increased risk of flooding or storm damage. This project impacts wetland management decisions. The contiguous U.S. has close to 2 million hectares of estuarine and marine wetlands. Nearly all of that area is under some level of management, with the federal government being the largest single manager. Land managers at FWS and NPS, and flood managers at ACOE, must make decisions regarding whether to spend substantial funds to maintain, repair and enhance water control structures under increasing rates of sea level change, or alternatively whether to reduce or remove hydrological management, to restore managed wetlands to more natural hydrology and enhance the capability of wetlands to build elevation over time, and to migrate landward. Society needs guidance and predictions regarding the result of those decisions for continued elevation gain, migration, and ongoing persistence of the wetlands.
Professional Experience
Present: Research Chemist, USGS Coastal and Marine Geology Program, Woods Hole Science Center, Woods Hole, MA
2004-2006: Mendenhall Fellow, US Geological Survey Geologic Division, St Petersburg, FL
2003-2004: Postdoctoral Scholar, Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA
1997-2003: Research Fellow and Teaching Fellow, Bos
Education and Certifications
PhD Boston University Marine Program (Biogeochemistry)
M.S. University of Connecticut (Marine Science)
B.A. University of Tennessee (Ecology)
Affiliations and Memberships*
Contributing Author: 2nd State of the Carbon Cycle Report (SOCCR-2), Chapter 15 Tidal Wetlands and Estuaries
Lead, USGS Woods Hole Coastal Biogeochemical Processes Project
Participant, 2017 EPA AFOL
Science and Products
Wetland Carbon Working Group: Improving Methodologies and Estimates of Carbon and Greenhouse Gas Flux in Wetlands
Submarine Groundwater Discharge
Global Science and Data Network for Coastal Blue Carbon (SBC)
NASA-USGS National Blue Carbon Monitoring System
Environmental Geochemistry
Advancing understanding of ecosystem responses to climate change with warming experiments: what we have learned and what is unknown?
Inventory of Managed Coastal Wetlands in Delaware Bay and Delaware's Inland Bays
Restoration and Conservation Opportunity Maps for the conterminous U.S. (CONUS)
Nearshore groundwater seepage and geochemical data measured in 2015 at Guinea Creek, Rehoboth Bay, Delaware
Carbon dioxide and methane fluxes with supporting environmental data from coastal wetlands across Cape Cod, Massachusetts (ver 2.0, June 2022)
Continuous Water Level, Salinity, and Temperature Data from Coastal Wetland Monitoring Wells, Cape Cod, Massachusetts (ver. 2.0, August 2022)
Static chamber gas fluxes and carbon and nitrogen isotope content of age-dated sediment cores from a Phragmites wetland in Sage Lot Pond, Massachusetts, 2013-2015
Geochemical data supporting analysis of fate and transport of nitrogen in the near shore groundwater and subterranean estuary near East Falmouth, Massachusetts, 2015
Collection, analysis, and age-dating of sediment cores from Herring River wetlands and other nearby wetlands in Wellfleet, Massachusetts, 2015-17
Collection, Analysis, and Age-Dating of Sediment Cores from Salt Marshes, Rhode Island, 2016
Collection, analysis, and age-dating of sediment cores from natural and restored salt marshes on Cape Cod, Massachusetts, 2015-16
Collection, analysis, and age-dating of sediment cores from mangrove and salt marsh ecosystems in Tampa Bay, Florida, 2015
Geochemical data supporting investigation of solute and particle cycling and fluxes from two tidal wetlands on the south shore of Cape Cod, Massachusetts, 2012-19 (ver. 2.0, October 2022)
Geologic carbon management options for the North Atlantic-Appalachian Region
Mapping methane reduction potential of tidal wetland restoration in the United States
High-frequency variability of carbon dioxide fluxes in tidal water over a temperate salt marsh
Forecasting sea level rise-driven inundation in diked and tidally restricted coastal lowlands
Higher temperature sensitivity of ecosystem respiration in low marsh compared to high elevation marsh ecosystems
Mechanisms and magnitude of dissolved silica release from a New England salt marsh
Soil carbon consequences of historic hydrologic impairment and recent restoration in coastal wetlands
Impoundment increases methane emissions in Phragmites-invaded coastal wetlands
Greenhouse gas balances in coastal ecosystems: Current challenges in “blue carbon” estimation and significance to national greenhouse gas inventories
Detection and characterization of coastal tidal wetland change in the northeastern US using Landsat time series
Estimating the aboveground biomass and carbon stocks of tall shrubs in a prerestoration degraded salt marsh
Oxygen-controlled recirculating seepage meter reveals extent of nitrogen transformation in discharging coastal groundwater at the aquifer–estuary interface
Science and Products
- Science
Wetland Carbon Working Group: Improving Methodologies and Estimates of Carbon and Greenhouse Gas Flux in Wetlands
WARC researchers are working to quantify the impacts of future climate and land use/land cover change on greenhouse gas emissions and reductions.Submarine Groundwater Discharge
We define submarine groundwater discharge (SGD) to consist either of fresh groundwater, re-circulated seawater, or a composite thereof. We evaluate and present SGD in terms of a vector for nutrient delivery to coastal waters.Global Science and Data Network for Coastal Blue Carbon (SBC)
The Global Science and Data Network for Coastal Blue Carbon (SBC) brings together scientists from a wide range of disciplines. Our goal is to increase the accuracy of and confidence in local, regional, and global estimates of carbon cycle processes, fluxes, and storage as well as greenhouse gas emissions from coastal ecosystems, and to allow global access to quality controlled coastal ecosystem...NASA-USGS National Blue Carbon Monitoring System
The NASA-USGS National Blue Carbon Monitoring System project will evaluate the relative uncertainty of iterative modeling approaches to estimate coastal wetland (marsh and mangrove) C stocks and fluxes based on changes in wetland distributions, using nationally available datasets (Landsat) and as well as finer scale satellite and field derived data in six sentinel sites.Environmental Geochemistry
Coastal Environmental Geochemistry research at the Woods Hole Coastal and Marine Science Center spans multiple ecosystems and topics, including coastal wetlands, aquifers, and estuaries, with the goal of providing data and guidance to federal, state, local, and private land owners and managers on these vital ecosystems.Advancing understanding of ecosystem responses to climate change with warming experiments: what we have learned and what is unknown?
Advancing our mechanistic understanding of ecosystem responses to climate change is critical to improve ecological theories, develop predictive models to simulate ecosystem processes, and inform sound policies to manage ecosystems and human activities. Manipulation of temperature in the field, or the “ecosystem warming experiment,” has proved to be a powerful tool to understand ecosystem responses... - Data
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Inventory of Managed Coastal Wetlands in Delaware Bay and Delaware's Inland Bays
This data release contains areas within Delaware Bay and Delaware Inland Bays that are within tidal elevations, as determined by the Highest Astronomical Tide (HAT), but that are classified as non-tidal or managed wetlands by the National Wetlands Inventory (NWI) or as non-estuarine by the 2016 Coastal Change Analysis Program (C-CAP) land cover dataset. These areas have been assigned the classificRestoration and Conservation Opportunity Maps for the conterminous U.S. (CONUS)
Nature-based solutions is a leading policy option for mitigating climate change. We mapped areas of potential restoration and conservation opportunities in the conterminous U.S. (CONUS). The potential for five scenarios were examined: increasing forest cover in urban centers, restoring historically forested areas that have been converted to grasslands, conserving pristine grasslands, rewetting peaNearshore groundwater seepage and geochemical data measured in 2015 at Guinea Creek, Rehoboth Bay, Delaware
Assessment of biogeochemical processes and transformations at the aquifer-estuary interface and measurement of the chemical flux from submarine groundwater discharge (SGD) zones to coastal water bodies are critical for evaluating ecosystem service, geochemical budgets, and eutrophication status. The U.S. Geological Survey and the University of Delaware measured rates of SGD and concentrations of dCarbon dioxide and methane fluxes with supporting environmental data from coastal wetlands across Cape Cod, Massachusetts (ver 2.0, June 2022)
Saline tidal wetlands are important sites of carbon sequestration and produce negligible methane (CH4) emissions due to regular inundation with sulfate-rich seawater. Yet, widespread management of coastal hydrology has restricted vast areas of coastal wetlands to tidal exchange. These ecosystems often undergo impoundment and freshening, which in turn cause vegetation shifts like invasion by PhragmContinuous Water Level, Salinity, and Temperature Data from Coastal Wetland Monitoring Wells, Cape Cod, Massachusetts (ver. 2.0, August 2022)
Environmental parameters affecting plant productivity and microbial respiration, such as water level, salinity, and groundwater temperature included in these datasets, are key components of wetland carbon cycling, carbon storage, and capacity to maintain elevation. Data were collected to (1) provide background data to evaluate potential differences in water level and carbon flux between wetland siStatic chamber gas fluxes and carbon and nitrogen isotope content of age-dated sediment cores from a Phragmites wetland in Sage Lot Pond, Massachusetts, 2013-2015
Coastal wetlands are major global carbon sinks, however, they are heterogeneous and dynamic ecosystems. To characterize spatial and temporal variability in a New England salt marsh, static chamber measurements of greenhouse gas (GHG) fluxes were compared among major plant-defined zones (high marsh dominated by Distichlis spicata and a zone of invasive Phragmites australis) during 2013 and 2014 groGeochemical data supporting analysis of fate and transport of nitrogen in the near shore groundwater and subterranean estuary near East Falmouth, Massachusetts, 2015
Geochemical data were obtained to investigate the fate and transport of nitrogen in a subterranean estuary near East Falmouth, Massachusetts. The goal of this investigation was to assess nitrogen attenuation in the aquifer under the Eel River Estuary and the adjacent peninsula that was densely populated with residences having septic systems and legacy cesspool inputs of inorganic nitrogen. This esCollection, analysis, and age-dating of sediment cores from Herring River wetlands and other nearby wetlands in Wellfleet, Massachusetts, 2015-17
The Herring River estuary in Wellfleet, Cape Cod, Massachusetts, has been tidally restricted for more than a century by a dike constructed near the mouth of the river. Upstream from the dike, the tidal restriction has caused the conversion of salt marsh wetlands to various other ecosystems including impounded freshwater marshes, flooded shrub land, drained forested upland, and brackish wetlands doCollection, Analysis, and Age-Dating of Sediment Cores from Salt Marshes, Rhode Island, 2016
The accretion history of fringing salt marshes in Narragansett Bay, Rhode Island, was reconstructed from sediment cores. Age models, based on excess lead-210 and cesium-137 radionuclide analysis, were constructed to evaluate how vertical accretion and carbon burial rates have changed during the past century. The Constant Rate of Supply (CRS) age model was used to date six cores collected from threCollection, analysis, and age-dating of sediment cores from natural and restored salt marshes on Cape Cod, Massachusetts, 2015-16
Nineteen sediment cores were collected from five salt marshes on the northern shore of Cape Cod where previously restricted tidal exchange was restored to part of the marshes. Cores were collected in duplicate from two locations within each marsh complex: one upstream and one downstream from the former tidal restriction (typically caused by an undersized culvert or a berm). The unaltered, naturalCollection, analysis, and age-dating of sediment cores from mangrove and salt marsh ecosystems in Tampa Bay, Florida, 2015
Coastal wetlands in Tampa Bay, Florida, are important ecosystems that deliver a variety of ecosystem services. Key to ecosystem functioning is wetland response to sea-level rise through accumulation of mineral and organic sediment. The organic sediment within coastal wetlands is composed of carbon sequestered over the time scale of the wetland’s existence. This study was conducted to provide inforGeochemical data supporting investigation of solute and particle cycling and fluxes from two tidal wetlands on the south shore of Cape Cod, Massachusetts, 2012-19 (ver. 2.0, October 2022)
Assessment of geochemical cycling within tidal wetlands and measurement of fluxes of dissolved and particulate constituents between wetlands and coastal water bodies are critical to evaluating ecosystem function, service, and status. The U.S. Geological Survey and collaborators collected surface water and porewater geochemical data from a tidal wetland located on the eastern shore of Sage Lot Pond - Multimedia
- Publications
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Geologic carbon management options for the North Atlantic-Appalachian Region
IntroductionThe U.S. Geological Survey (USGS) North Atlantic-Appalachian Region is developing the regionwide capacity to provide timely science support for decision-makers attempting to enhance carbon removal, sequestration, and emissions mitigation to meet national atmospheric carbon reduction goals. The U.S. Environmental Protection Agency (EPA) reported that in 2021, the fourteen States and theAuthorsPeter D. Warwick, Madalyn S. Blondes, Sean T. Brennan, Steven M. Cahan, C. Özgen Karacan, Kevin D. Kroeger, Matthew D. MerrillMapping methane reduction potential of tidal wetland restoration in the United States
Coastal wetlands can emit excess methane in cases where they are impounded and artificially freshened by structures that impede tidal exchange. We provide a new assessment of coastal methane reduction opportunities for the contiguous United States by combining multiple publicly available map layers, reassessing greenhouse gas emissions datasets, and applying scenarios informed by geospatial informAuthorsJames Holmquist, Meagan Eagle, Rebecca Molinari, Sydney K. Nick, Liana Stachowicz, Kevin D. KroegerHigh-frequency variability of carbon dioxide fluxes in tidal water over a temperate salt marsh
Existing analyses of salt marsh carbon budgets rarely quantify carbon loss as CO2 through the air–water interface in inundated marshes. This study estimates the variability of partial pressure of CO2 (pCO2) and air–water CO2 fluxes over summer and fall of 2014 and 2015 using high-frequency measurements of tidal water pCO2 in a salt marsh of the U.S. northeast region. Monthly mean CO2 effluxes variAuthorsShuzhen Song, Zhaohui Aleck Wang, Kevin D. Kroeger, Meagan Eagle, Sophie N. Chu, Jianzhong GeForecasting sea level rise-driven inundation in diked and tidally restricted coastal lowlands
Diked and drained coastal lowlands rely on hydraulic and protective infrastructure that may not function as designed in areas with relative sea-level rise. The slow and incremental loss of the hydraulic conditions required for a well-drained system make it difficult to identify if and when the flow structures no longer discharge enough water, especially in tidal settings where two-way flows occurAuthorsKevin A. Befus, A Kurnizki, Kevin D. Kroeger, Meagan Eagle, Timothy P. SmithHigher temperature sensitivity of ecosystem respiration in low marsh compared to high elevation marsh ecosystems
Salt marsh habitats contain some of the highest quantities of soil organic carbon (C) per unit area, but increasing anthropogenic stressors threaten their ability to maintain themselves as large C reservoirs in some regions. We quantify rates of C gas exchange (methane [CH4] and carbon dioxide [CO2]) monthly across a 16-month period from a low nitrogen “reference” salt marsh on Cape Cod in New EngAuthorsJoanna C. Carey, Kevin D. Kroeger, Jianwu TangMechanisms and magnitude of dissolved silica release from a New England salt marsh
Salt marshes are sites of silica (SiO2) cycling and export to adjacent coastal systems, where silica availability can exert an important control over coastal marine primary productivity. Mineral weathering and biologic fixation concentrate silica in these systems; however, the relative contributions of geologic versus biogenic silica dissolution to this export are not known. We collected water samAuthorsOlivia Williams, Andrew C. Kurtz, Meagan Eagle, Kevin D. Kroeger, Joseph Tamborski, Joanna C. CareySoil carbon consequences of historic hydrologic impairment and recent restoration in coastal wetlands
Coastal wetlands provide key ecosystem services, including substantial long-term storage of atmospheric CO2 in soil organic carbon pools. This accumulation of soil organic matter is a vital component of elevation gain in coastal wetlands responding to sea-level rise. Anthropogenic activities that alter coastal wetland function through disruption of tidal exchange and wetland water levels are ubiquAuthorsMeagan Eagle, Kevin D. Kroeger, Amanda C. Spivak, Faming Wang, Jianwu Tang, Omar I. Abdul-Aziz, Khandker S. Ishtiaq, Jennifer A. O'Keefe Suttles, Adrian G. MannImpoundment increases methane emissions in Phragmites-invaded coastal wetlands
Saline tidal wetlands are important sites of carbon sequestration and produce negligible methane (CH4) emissions due to regular inundation with sulfate-rich seawater. Yet, widespread management of coastal hydrology has restricted tidal exchange in vast areas of coastal wetlands. These ecosystems often undergo impoundment and freshening, which in turn cause vegetation shifts like invasion by PhragmAuthorsRebecca Sanders-DeMott, Meagan Eagle, Kevin D. Kroeger, Faming Wang, Thomas W. Brooks, Jennifer A. O'Keefe Suttles, Sydney K. Nick, Adrian G. Mann, Jianwu TangGreenhouse gas balances in coastal ecosystems: Current challenges in “blue carbon” estimation and significance to national greenhouse gas inventories
Coastal wetlands are defined herein as inundated, vegetated ecosystems with hydrology, and biogeochemistry influenced by sea levels, at timescales of tides to millennia. Coastal wetlands are necessary components of global greenhouse gas estimation and scenario modeling, both for continental and oceanic mass balances. The carbon pools and fluxes on coastal lands, especially those influenced by tidaAuthorsLisamarie Windham-Myers, James R. Holmquist, Kevin D. Kroeger, Tiffany G. TroxlerDetection and characterization of coastal tidal wetland change in the northeastern US using Landsat time series
Coastal tidal wetlands are highly altered ecosystems exposed to substantial risk due to widespread and frequent land-use change coupled with sea-level rise, leading to disrupted hydrologic and ecologic functions and ultimately, significant reduction in climate resiliency. Knowing where and when the changes have occurred, and the nature of those changes, is important for coastal communities and natAuthorsXiucheng Yang, Zhe Zhu, Shirley Qiu, Kevin D. Kroeger, Zhiliang Zhu, Scott CovingtonEstimating the aboveground biomass and carbon stocks of tall shrubs in a prerestoration degraded salt marsh
Wetlands play a vital role in Earth's carbon cycle and provide important ecosystem services. Their ability to perform their roles can be compromised by human activities that destroy or impair their functioning. The restoration of degraded wetlands may allow carbon cycle functioning, as well as other services, to be recovered. Predicting the potential outcomes from any restoration project requiresAuthorsJacqualyn Fouse, Meagan Eagle, Kevin D. Kroeger, Timothy P. SmithOxygen-controlled recirculating seepage meter reveals extent of nitrogen transformation in discharging coastal groundwater at the aquifer–estuary interface
Nutrient loads delivered to estuaries via submarine groundwater discharge (SGD) play an important role in the nitrogen (N) budget and eutrophication status. However, accurate and reliable quantification of the chemical flux across the final decimeters and centimeters at the sediment–estuary interface remains a challenge, because there is significant potential for biogeochemical alteration due to cAuthorsThomas W. Brooks, Kevin D. Kroeger, Holly A. Michael, Joanna K. York - 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