Meagan J. Eagle , PhD
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
Continuous Monitoring Data From Herring River Wetlands Cape Cod, Massachusetts, 2015-Jan2020
Continuous Monitoring Data From Great Barnstable Marsh on Cape Cod, Massachusetts, 2017-19
Tidal marsh biomass field plot and remote sensing datasets for six regions in the conterminous United States (ver. 2.0, June 2020)
Continuous monitoring data from natural and restored salt marshes on Cape Cod, Massachusetts, 2016-17
Time-series of biogeochemical and flow data from a tidal salt-marsh creek, Sage Lot Pond, Waquoit Bay, Massachusetts, 2012-2016 (ver. 2.0, July 2023)
Collection, analysis, and age-dating of sediment cores from salt marshes on the south shore of Cape Cod, Massachusetts, from 2013 through 2014
Meagan Eagle's publications
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)
Recent carbon storage and burial exceed historic rates in the San Juan Bay estuary peri-urban mangrove forests (Puerto Rico, United States)
Pore water exchange-driven inorganic carbon export from intertidal salt marshes
Groundwater discharge impacts marine isotope budgets of Li, Mg, Ca, Sr, and Ba
Soil organic carbon development and turnover in natural and disturbed salt marsh environments
Modeling the spatial dynamics of marsh ponds in New England salt marshes
Plant biomass and rates of carbon dioxide uptake are enhanced by successful restoration of tidal connectivity in salt marshes
An important biogeochemical link between organic and inorganic carbon cycling: Effects of organic alkalinity on carbonate chemistry in coastal waters influenced by intertidal salt marshes
Getting to the core of the matter
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Filter Total Items: 18
Continuous Monitoring Data From Herring River Wetlands Cape Cod, Massachusetts, 2015-Jan2020
The Herring River estuary (Wellfleet, Cape Cod, Massachusetts) has been tidally restricted for over a century by a dike constructed near the mouth of the river. Behind 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 wetlands dominated by Phragmites aContinuous Monitoring Data From Great Barnstable Marsh on Cape Cod, Massachusetts, 2017-19
Salt marshes are environmental ecosystems that contribute to coastal landscape resiliency to storms and rising sea level. Ninety percent of mid-Atlantic and New England salt marshes have been impacted by parallel grid ditching that began in the 1920s–40s to control mosquito populations and to provide employment opportunities during the Great Depression (James-Pirri and others, 2009; Kennish, 2001)Tidal marsh biomass field plot and remote sensing datasets for six regions in the conterminous United States (ver. 2.0, June 2020)
Remote sensing based maps of tidal marshes, both of their extents and carbon stocks, have the potential to play a key role in conducting greenhouse gas inventories and implementing climate mitigation policies. Our objective was to generate a single remote sensing model of tidal marsh aboveground biomass and carbon that represents nationally diverse tidal marshes within the conterminous United StatContinuous monitoring data from natural and restored salt marshes on Cape Cod, Massachusetts, 2016-17
Continuous monitoring data reported are a portion of data from a larger study investigating changes in soil properties, carbon accumulation, and greenhouse gas fluxes in four recently restored salt marsh sites and nearby natural salt marshes. For several decades, local towns, conservation groups, and government organizations have worked to identify, replace, repair, and enlarge culverts to restoreTime-series of biogeochemical and flow data from a tidal salt-marsh creek, Sage Lot Pond, Waquoit Bay, Massachusetts, 2012-2016 (ver. 2.0, July 2023)
Extended time-series sensor data were collected between 2012 and 2016 in surface water of a tidal salt-marsh creek on Cape Cod, Massachusetts. The objective of this field study was to measure water chemical characteristics and flows, as part of a study to quantify lateral fluxes of dissolved carbon species between the salt marsh and estuary. Data consist of in-situ measurements including: salinityCollection, analysis, and age-dating of sediment cores from salt marshes on the south shore of Cape Cod, Massachusetts, from 2013 through 2014
The accretion history of fringing salt marshes located on the south shore of Cape Cod is reconstructed from sediment cores collected in low and high marsh vegetation zones. These marshes are micro-tidal, with a mean tidal range of 0.442 m. Their location within protected embayments and the absence of large rivers results in minimal sediment supply and a dominance of organic matter contributions to - Multimedia
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Meagan Eagle's publications
Filter Total Items: 33Revisiting 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 J. 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 J. 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 J. 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 J. Eagle, Alana Hanson, Rose M. Martin, Stephen Balogh, Kenneth Miller, Evelyn Huertas, Joseph Loffredo, Elizabeth WatsonRecent carbon storage and burial exceed historic rates in the San Juan Bay estuary peri-urban mangrove forests (Puerto Rico, United States)
Mangroves sequester significant quantities of organic carbon (C) because of high rates of burial in the soil and storage in biomass. We estimated mangrove forest C storage and accumulation rates in aboveground and belowground components among five sites along an urbanization gradient in the San Juan Bay Estuary, Puerto Rico. Sites included the highly urbanized and clogged Caño Martin Peña in the wAuthorsCathleen Wigand, Meagan J. Eagle, Benjamin Branoff, Stephen Balogh, Kenneth Miller, Rose M. Martin, Alana Hanson, Autumn Oczkowski, Evelyn Huertas, Joseph Loffredo, Elizabeth WatsonPore water exchange-driven inorganic carbon export from intertidal salt marshes
Respiration in intertidal salt marshes generates dissolved inorganic carbon (DIC) that is exported to the coastal ocean by tidal exchange with the marsh platform. Understanding the link between physical drivers of water exchange and chemical flux is a key to constraining coastal wetland contributions to regional carbon budgets. The spatial and temporal (seasonal, annual) variability of marsh poreAuthorsJoseph Tamborski, Meagan J. Eagle, Barret L. Kurylyk, Kevin D. Kroeger, Zhaoihui Wang, Paul Henderson, Matthew CharetteGroundwater discharge impacts marine isotope budgets of Li, Mg, Ca, Sr, and Ba
Groundwater-derived solute fluxes to the ocean have long been assumed static and subordinate to riverine fluxes, if not neglected entirely, in marine isotope budgets. Here we present concentration and isotope data for Li, Mg, Ca, Sr, and Ba in coastal groundwaters to constrain the importance of groundwater discharge in mediating the magnitude and isotopic composition of terrestrially derived solutAuthorsKimberly Mayfield, Anton Eisenhauer, Danielle P. Santiago Ramos, John A. Higgins, Tristan Horner, Maureen Auro, Tomas Magna, Nils Moosdorf, Matthew Charette, Meagan Gonneea Eagle, Carolyn Brady, Nemanja Komar, Bernhard Peucker-Ehrenbrink, Adina PaytanSoil organic carbon development and turnover in natural and disturbed salt marsh environments
Salt marsh survival with sea‐level rise (SLR) increasingly relies on soil organic carbon (SOC) accumulation and preservation. Using a novel combination of geochemical approaches, we characterized fine SOC (≤1 mm) supporting marsh elevation maintenance. Overlaying thermal reactivity, source (δ13C), and age (F14C) information demonstrates several processes contributing to soil development: marsh graAuthorsSheron Luk, Katherine Todd-Brown, Meagan J. Eagle, Ann McNichol, Jonathan Sanderman, Kelsey Gosselin, Amanda C. SpivakModeling the spatial dynamics of marsh ponds in New England salt marshes
Ponds are common features on salt marshes, yet it is unclear how they affect large-scale marsh evolution. We developed a spatially explicit model that combines cellular automata for pond formation, expansion, and drainage, and partial differential equations for elevation dynamics. We use the mesotidal Barnstable marsh (MA, USA) as a case study, for which we measured pond expansion rate by remote sAuthorsG. Mariotti, A. Spivak, S.Y. Luk, G. Ceccherini, M. Tyrrell, Meagan Gonneea EaglePlant biomass and rates of carbon dioxide uptake are enhanced by successful restoration of tidal connectivity in salt marshes
Salt marshes, due to their capability to bury soil carbon (C), are potentially important regional C sinks. Efforts to restore tidal flow to former salt marshes have increased in recent decades in New England (USA), as well as in some other parts of the world. In this study, we investigated plant biomass and carbon dioxide (CO2) fluxes at four sites where restoration of tidal flow occurred five toAuthorsFanning Wang, Meagan J. Eagle, Kevin D. Kroeger, Amanda C. Spivak, Jianwu TangAn important biogeochemical link between organic and inorganic carbon cycling: Effects of organic alkalinity on carbonate chemistry in coastal waters influenced by intertidal salt marshes
Organic acid charge groups in dissolved organic carbon (DOC) contribute to total alkalinity (TA), i.e. organic alkalinity (OrgAlk). Its effect is often ignored or treated as a calculation uncertainty in many aquatic CO2 studies. This study evaluated the variability, sources, and characteristics of OrgAlk in estuarine waters exchanged tidally with a groundwater-influenced salt marsh in the northeasAuthorsShuzhen Song, Zhaohui Aleck Wang, Meagan Gonneea Eagle, Kevin D. Kroeger, Sophie N. Chu, Daoji Li, Haorui LiangGetting to the core of the matter
The topic of carbon sequestration in coastal salt marshes can serve as the basis of an investigation story line with plenty of authentic relevance and drama! Consider establishing the context with students as an introduction to this lesson. Many resources for teaching about carbon uptake and sequestration in coastal wetlands can be found at the Bringing Wetlands to Market website. Some of the elemAuthorsMeagan Gonneea Eagle - News