My research lies at the interface of land and sea and is used to build new tools to address coastal hazards. This dynamic region is experiencing rapid change, with new pressures from rising temperatures and sea level adding to those already wrought by the impacts of coastal development.
I utilize a suite of geochemical tools, including naturally occurring radioisotopes in the Uranium-Thorium decay series, to understand both the magnitude and rate of change within coastal ecosystems. In particular, I am interested in how salt marshes have responded to a century of accelerating sea level rise, with a focus on their ability to store carbon and dynamically build elevation. I combine historical ecosystem information, gleaned from analysis of salt marsh peat, with modern environmental drivers to constrain future ecosystem responses.
I studied geology at Stanford University (BS/MS) and received a PhD in Chemical Oceanography from the Massachusetts Institute of Technology and Woods Hole Oceanographic Institution Joint Program. There I studied groundwater discharge and associated chemical fluxes. Between going to school, I did a Fulbright Fellowship in Mauritius and worked at Woods Hole Oceanographic Institution. I came to the Woods Hole Coastal and Marine Science Center of the US Geological Survey in 2013 and have worked on coastal wetland and groundwater projects across the US.
Science and Products
Environmental Geochemistry
Concentrations of Per- and Polyfluoroalkyl Substances (PFAS) in Lake-Bottom Sediments of Ashumet Pond on Cape Cod, Massachusetts, 2020
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
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
Collection, analysis, and age-dating of sediment cores from mangrove wetlands in San Juan Bay Estuary, Puerto Rico, 2016
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)
Collection, analysis, and age-dating of sediment cores from a salt marsh platform and ponds, Rowley, Massachusetts, 2014-15
Meagan Eagle's publications
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
The blue carbon reservoirs from Maine to Long Island, NY
Forecasting sea level rise-driven inundation in diked and tidally restricted coastal lowlands
Peat decomposition and erosion contribute to pond deepening in a temperate salt marsh
Mechanisms and magnitude of dissolved silica release from a New England salt marsh
CO2 uptake offsets other greenhouse gas emissions from salt marshes with chronic nitrogen loading
Soil carbon consequences of historic hydrologic impairment and recent restoration in coastal wetlands
Revisiting 228Th as a tool for determining sedimentation and mass accumulation rates
Impoundment increases methane emissions in Phragmites-invaded coastal wetlands
Estimating the aboveground biomass and carbon stocks of tall shrubs in a prerestoration degraded salt marsh
Recent nitrogen storage and accumulation rates in mangrove soils exceed historic rates in the urbanized San Juan Bay Estuary (Puerto Rico, United States)
Science and Products
- Science
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. - Data
Filter Total Items: 18
Concentrations of Per- and Polyfluoroalkyl Substances (PFAS) in Lake-Bottom Sediments of Ashumet Pond on Cape Cod, Massachusetts, 2020
Lake-bottom sediment and associated quality-control samples were collected in August 2020 from one coring location (U.S. Geological Survey station 413756070321301, ASHUMET POND, MASHPEE MI-ASHPD-0011) in Ashumet Pond downgradient from a former fire-training area on Cape Cod, Massachusetts. The core was collected to determine if per- and polyfluoroalkyl substances (PFAS) were present in the bottomNearshore 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 groCollection, 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 inforCollection, analysis, and age-dating of sediment cores from mangrove wetlands in San Juan Bay Estuary, Puerto Rico, 2016
The San Juan Bay Estuary, Puerto Rico, contains mangrove forests that store significant amounts of organic carbon in soils and biomass. There is a strong urbanization gradient across the estuary, from the highly urbanized and clogged Caño Martin Peña in the western part of the estuary, a series of lagoons in the center of the estuary, and a tropical forest reserve (Piñones) in the easternmost partGeochemical 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 PondCollection, analysis, and age-dating of sediment cores from a salt marsh platform and ponds, Rowley, Massachusetts, 2014-15
Sediment cores were collected from three sites within the Plum Island Ecosystems Long-Term Ecological Research (PIE-LTER) domain in Massachusetts to obtain estimates of long-term marsh decomposition and evaluate shifts in the composition and reactivity of sediment organic carbon in disturbed marsh environments. Paired sediment cores were collected from three sites on the marsh platform and from th - Multimedia
- Publications
Meagan Eagle's publications
Filter Total Items: 29Mapping 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 GeThe blue carbon reservoirs from Maine to Long Island, NY
In response to the New England Governor and Eastern Canadian Premier 2017 Climate Change Action Plan recommendation to “manage blue carbon resources to preserve and enhance their existing carbon reservoirs,” the U.S. Environmental Protection Agency (EPA) convened a New England Blue Carbon Inventory Workgroup, comprised of a variety of federal, state, academic, and non-profit organizations to develAuthorsPhilip D. Colarusso, Zamir Libohova, Emily Shumchenia, Meagan Eagle, Megan Christian, Robert Vincent, Beverly JohnsonForecasting 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. SmithPeat decomposition and erosion contribute to pond deepening in a temperate salt marsh
Salt marsh ponds expand and deepen over time, potentially reducing ecosystem carbon storage and resilience. The water filled volumes of ponds represent missing carbon due to prevented soil accumulation and removal by erosion and decomposition. Removal mechanisms have different implications as eroded carbon can be redistributed while decomposition results in loss. We constrained ponding effects onAuthorsSheron Luk, Meagan Eagle, Giulio Mariotti, Kelsey Gosselin, Jonathan Sanderman, Amanda C. SpivakMechanisms 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. CareyCO2 uptake offsets other greenhouse gas emissions from salt marshes with chronic nitrogen loading
Coastal wetlands are known for exceptional productivity, but they also receive intense land-based nitrogen (N) loading. In Narragansett Bay, RI (USA), coastal ecosystems have received anthropogenic N inputs from wastewater for more than two centuries. Greenhouse gas fluxes were studied throughout a growing season (2016) in three coastal wetlands with contrasting histories of nitrogen loading. TheAuthorsSerena Moseman-Valtierra, Katelyn Szura, Meagan Eagle, Carol Thornber, Faming WangSoil 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. MannRevisiting 228Th as a tool for determining sedimentation and mass accumulation rates
The use of 228Th has seen limited application for determining sedimentation and mass accumulation rates in coastal and marine environments. Recent analytical advances have enabled rapid, precise measurements of particle-bound 228Th using a radium delayed coincidence counting system (RaDeCC). Herein we review the 228Th cycle in the marine environment and revisit the historical use of 228Th as a traAuthorsJoseph Tamborski, Pinghe Cai, Meagan Eagle, Paul Henderson, Matthew CharetteImpoundment 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 TangEstimating 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. SmithRecent nitrogen storage and accumulation rates in mangrove soils exceed historic rates in the urbanized San Juan Bay Estuary (Puerto Rico, United States)
Tropical mangrove forests have been described as “coastal kidneys,” promoting sediment deposition and filtering contaminants, including excess nutrients. Coastal areas throughout the world are experiencing increased human activities, resulting in altered geomorphology, hydrology, and nutrient inputs. To effectively manage and sustain coastal mangroves, it is important to understand nitrogen (N) stAuthorsCathleen Wigand, Autumn Oczkowski, Benjamin Branoff, Meagan Eagle, Alana Hanson, Rose M. Martin, Stephen Balogh, Kenneth Miller, Evelyn Huertas, Joseph Loffredo, Elizabeth Watson - News