Abstract: Air/water exchanges of gasses are important for both local biogeochemical cycles and for large scale climate change. Typically, these gas exchanges are parameterized as a function of wind speed without any direct consideration of the local turbulence or surface waves that are physically relevant to these transfers. As such, these parameterizations fail in coastal areas where waves are limited by fetch and modified by local currents and bathymetry. We propose a fetch-dependent gas transfer velocity based on existing theory for near surface turbulence and wave growth. We propose to test this new parameterization with local measurements in Waquoit Bay under a range of fetch and wind speeds. This parameterization will help the biogeochemical community estimate gas fluxes with simple inputs (locally measured wind speed and fetch from Google maps) without a need for measurements of complex turbulent dynamics. With increasing attention to the large role that coastal and estuarine environments play in global biogeochemical cycling, there is a growing consensus that better estimates of air/water exchange are needed to accurately describe their importance, as well as how this may be altered due to local anthropogenic influence and global climate change.
Project Title: Greenhouse Gas Measurement at Sage Lot
Principal Investigator(s): Dr. Jim Tang, Dr. Faming Wang
Summary: In this study, we continued the field gas flux measurements at Sage lot salt marsh. We installed 4-inch diameter collars for soil respiration measurement, and big collar (20 inch) for the ecosystem level measurements. We installed warming chambers to heat the marsh to mimic the warming effect and measure the response of greenhouse gas fluxes to warming. The aim of this study is to measure CO2 and CH4 fluxes in the pristine salt marsh, and support our project to study New England Salt marsh blue carbon.
Summary: Salt marshes provide significant environmental and economic value by shielding coastal communities against storm-surges and sequestering CO2 from the atmosphere, acting as a natural buffer to climate change. Carbon is both buried by marsh plants and exported to the coastal ocean from tidal drainage. However, the spatial variability of carbon export from tidal drainage across a salt marsh platform is largely unknown. Our two main objectives are to  characterize salt marsh hydrology under present and future climate scenarios; and  to determine the spatial and temporal variability of carbon export from tidal marsh drainage. Sediment cores, marsh pore waters and vertical temperature profiles will be sampled across marsh platforms, toward the tidal creek, to help reveal spatial patterns in seasonal exchange fluxes. Hydrogeological models will be used to assess salt marsh resiliency to changing climate scenarios. These tasks aim to reveal how salt marshes impact carbon cycling and biogeochemistry of the Northwest Atlantic and identify the vulnerability of these critical wetlands to changing terrestrial and marine conditions.
Project Title: Photochemical degradation of dissolved organic carbon at Waquoit Bay
Principal Investigator(s): Collin Ward, Sam McNichol
Summary: Dissolved organic carbon is a central intermediate in the global carbon cycle. For nearly fifty years we’ve known that sunlight can alter the chemical make-up of dissolved organic carbon, which changes how fast microbes respire it to carbon dioxide. However, very little is known about the rate that this coupled photochemical biological reaction occurs. In this study, we are using Waquoit Bay as a field site to test a new method to quantify photochemical biological dissolved organic carbon degradation. The facility is ideal because (i) it offers easy access to diverse water types (i.e., lake, river, groundwater, estuarine), and (ii) water quality data is continuously monitored.
Project Title: Carbon dioxide fluxes reflect plant zonation and below ground biomass in a coastal marsh
Principal Investigators: Moseman‐Valtierra, S., Abdul‐Aziz, O. I., Tang, J., Ishtiaq, K. S., Morkeski, K., Mora, J., & Carey, J.
Summary: 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, greenhouse gas (GHG) fluxes were compared among major plant‐defined zones during growing seasons. Carbon dioxide (CO2) and methane (CH4) fluxes were compared in two mensurative experiments during summer months (2012–2014) that included low marsh (Spartina alterniflora), high marsh (Distichlis spicata and Juncus gerardii‐dominated), invasive Phragmites australis zones, and unvegetated ponds. Read Full text…Ecosphere, 7(11). http://onlinelibrary.wiley.com/doi/10.1002/ecs2.1560/full
Project Title: Sediment nitrous oxide fluxes are dominated by uptake in a temperate estuary
Principal Investigator(s): Foster, S.Q., & Fulweiler, R.W.
Summary: Coastal marine ecosystems are generally considered important sources of nitrous oxide (N2O), a powerful greenhouse gas and ozone depleting substance. To date most studies have focused on the environmental factors controlling N2O production although N2O uptake has been observed in a variety of coastal ecosystems. In this study, we examined sediment fluxes of N2O during 2 years (2012–2013) in a shallow temperate estuary (Waquoit Bay, MA, USA). Read full text…Frontiers in Marine Science, 3, 40. http://journal.frontiersin.org/article/10.3389/fmars.2016.00040/full
Project Title: Evaluation of laser-based spectrometers for greenhouse gas flux measurements in coastal marshes
Principal Investigator(s): Brannon, E. Q., Moseman-Valtierra, S. M., Rella, C.W., Martin, R.M., Chen, X. and Tang, J.
Abstract: Precise and rapid analyses of greenhouse gases (GHGs) will advance understanding of the net climatic forcing of coastal marsh ecosystems. We examined the ability of a cavity ring down spectroscopy (CRDS) analyzer (Model G2508, Picarro) to measure carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) fluxes in real‐time from coastal marshes through comparisons with a Shimadzu GC‐2014 (GC) in a marsh mesocosm experiment and with a similar laser‐based N2O analyzer (Model N2O/CO, Los Gatos Research) in both mesocosm and field experiments. Read full text… Limnol. Oceanogr. Methods, 14: 466–476. doi:10.1002/lom3.10105. http://onlinelibrary.wiley.com/doi/10.1002/lom3.10105/full
Project Title: Potential Effects of Sea-Level Rise on the Depth to Saturated Sediments of the Sagamore and Monomoy Flow Lenses on Cape Cod, Massachusetts
Principal Investigator(s): Bay, C.C.
Publication: In 2014, the U.S. Geological Survey, in cooperation with the Association to Preserve Cape Cod, the Cape Cod Commission, and the Massachusetts Environmental Trust, began an evaluation of the potential effects of sea-level rise on water table altitudes and depths to water on central and western Cape Cod, Massachusetts. Increases in atmospheric and oceanic temperatures arising, in part, from the release of greenhouse gases likely will result in higher sea levels globally. Read/download full text…https://pubs.usgs.gov/sir/2016/5058/sir20165058.pdf
Abstract: We use the term “primary producers” to include a large variety of organisms that manufacture organic compounds, by either photosynthesis or chemosynthesis. Photosynthetic primary producers use light-derived energy to convert carbon dioxide into organic carbon compounds that are integrated into cells. Read full text…In Marine Ecological Processes (pp. 3-34). Springer New York. https://link.springer.com/chapter/10.1007/978-0-387-79070-1_1
Project Title: Greenhouse gas fluxes vary between Phragmites australis and native vegetation zones in coastal wetlands along a salinity gradient
Principal Investigator(s): Martin, R.M., & Moseman-Valtierra, S.
Summary: The replacement of native species by invasive Phragmites australis in coastal wetlands may impact ecosystem processes including fluxes of the greenhouse gases (GHGs) carbon dioxide (CO2) and methane (CH4). To investigate differences in daytime CH4 and CO2 fluxes as well as vegetation properties between Phragmites and native vegetation zones along a salinity gradient, fluxes were measured via cavity ringdown spectroscopy in 3 New England coastal marshes, ranging from oligohaline to polyhaline. Read full text…Wetlands, 35(6),1021-1031. https://link.springer.com/article/10.1007/s13157-015-0690-y
Project Title: Corrigendum: Spatial and historic variability of benthic nitrogen cycling in an anthropogenically impacted estuary
Principal Investigator(s): Foster, S.Q., & Fulweiler, R.W.
Summary: The authors wish to include the following correction based on updated di-nitrogen (N2) gas flux values for three cores included in the original paper (the N2 flux values for the other 38 cores remain unchanged). This update was made in order to be consistent in our N2 flux calculations across all cores. In the three aforementioned cores we originally used a different method to account for the instrument drift of the mass spectrometer during sample analysis. Importantly, the correction of the flux values for these three cores is small and does not change any of our data interpretations. Read full text…Frontiers in Marine Science, 2, 70. http://journal.frontiersin.org/article/10.3389/fmars.2015.00070/full
PIs: Serena Moseman-Valtierra, University of Rhode Island, Jianwu Tang, MBL Ecosystems Center, Kevin Kroeger, USGS-Woods Hole Science Center,
Funding: MIT Seagrant
The general goal for the project is to measure potential greenhouse gas (GHG) emissions and net CO2 uptake in coastal wetlands under a range of realistic nitrogen (N) loads and inundation (sea) levels. By meeting this goal, we aim to improve the information with which managers and policy makers can maintain and maximize ecosystem productivity, reduce harmful feedbacks of climate, and assess the potential for these ecosystems to enter C markets.
We will examine how GHG emissions from salt marshes vary along an existing gradient of anthropogenic N loading in Waquoit Bay, MA (WB-NERR). Further, we will test for relationships between N loads to the marshes and plant productivity. To investigate the influence of anticipated future increases in sea level, we will use existing gradients in marsh soil elevation (and therefore a gradient in soil water saturation and in frequency and duration of soil inundation) as a space-for-time substitution simulating future inundation of soils.
Project Title: Carbon Management in Coastal Wetlands: Quantifying Carbon Storage and Greenhouse Gas Emissions by Tidal Wetlands to Support Development of a Greenhouse Gas Protocol and Economic Assessment
Project Lead: Alison Leschen, Waquoit Bay Reserve Manager
Collaborative Lead: Tonna-Marie Rogers, Waquoit Bay Coastal Training Program Coordinator
Principal Investigator(s): Jianwu Tang, MBL Ecosystems Center, Kevin Kroeger, USGS-Woods Hole Science Center, Neil K. Ganju, USGS-Woods Hole Science Center, Serena Moseman-Valtierra, University of RI, Omar Abdul-Aziz, Florida International Univ., Stephen Emmett-Mattox, Restore America’s Estuaries, Igino Emmer, Silvestrum, Stephen Crooks, Consultant to RAE, Pat Megonigal, Smithsonian ERC, Thomas Walker, Manomet CCS, Chris Weidman, Waquoit Bay Reserve Research Coordinator,
Funding: NERRS Science Collaborative
Summary: Increasing atmospheric concentrations of three major greenhouse gases (GHG) are the main drivers of climate change. Efforts to ameliorate rising levels of GHG include the protection and restoration of ecosystems that constitute major carbon (C) sinks and minor sources of CH4 and N2O emissions. Tidal marshes are prime candidates for such efforts as their sediments display high C sequestration. Loss of wetlands through human impacts such as land conversion, sediment supply disruption, nutrient loading, and with sea level rise, reduces future sequestration capacity and places at risk stores of C that built up over past centuries. Improved management of coastal C and nitrogen (N), based upon sound science, is a critical first step towards mitigation of climate change and management of coastal ecosystems. Management must address N loading that has the dual impact of 1) contributing to climate change through production of N2O, and 2) reducing production of root and soil matter by plants which can decrease the C sequestration capacity and resilience of marshes to sea level rise. Recognition of the importance of coastal marine systems in terms of C storage has led to national and international efforts to place monetary value on preserving or restoring the “blue carbon” in those systems, analogous to the value placed on forests. The barrier to incorporation of tidal wetlands into C markets is the absence of agreed upon GHG offset protocols that set guidelines for monitoring and verification requirements for wetlands projects, and a lack of data and knowledge regarding C and GHG fluxes in wetlands to support model development.
The project goals are to provide scientific information that can inform both C and N management as well as wetlands protection and restoration strategies for supporting development of policy frameworks and market-based mechanisms to reduce GHG.