The U.S. Northeast Shelf Large Marine Ecosystem, supports some of the nation’s most economically valuable coastal fisheries, yet most of this revenue comes from shellfish that are sensitive to ocean acidification (OA). Furthermore, the weakly buffered northern region of this area is expected to have greater susceptibility to OA. Existing OA observations in the NES do not sample at the time, space, and depth scales needed to capture the physical, biological, and chemical processes occurring in this dynamic coastal shelf region. Specific to inorganic carbon and OA, the data available in the region has not been leveraged to conduct a comprehensive regional-scale analysis that would increase the ability to understand and model seasonal-scale, spatial-scale, and subsurface carbonate chemistry dynamics, variability, and drivers in the NES. This project optimizes the NES OA observation network encompassing the Mid-Atlantic and Gulf of Maine regions by adding seasonal deployments of underwater gliders equipped with transformative, newly developed and tested deep ISFET-based pH sensors and additional sensors (measuring temperature, salinity for total alkalinity and aragonite saturation [ΩArag] estimation, oxygen, and chlorophyll), optimizing existing regional sampling to enhance carbonate chemistry measurements in several key locations, and compiling and integrating existing OA assets. The researchers will apply these data to an existing NES ocean ecosystem/biogeochemical (BGC) model that resolves carbonate chemistry and its variability.
Over the past 15 years, waters in the Gulf of Maine have taken up
CO2at a rate significantly slower than that observed in the open oceans due to a combination of
the extreme warming experienced in the region and an increased presence of well-buffered Gulf
Stream water. The reduced uptake of CO2 by the shelves could
also alter local acidification rate, which differ from the global rates. The intrusion of
anthropogenic CO2is not the only mechanism that can reduce Ωarag within coastal surface waters.
Local processes like freshwater delivery, eutrophication, water column metabolism, and
sediment interactions that drive variability on regional scales can also modify spatial variability
in Ωarag. Global projections cannot resolve these local processes with resolution of a degree
or more. Some high-resolution global projections have been developed which perform well in
some coastal settings . However, these simulations do not include regional
biogeochemical processes described above which can amplify or dampen these global changes,
particularly in coastal shelf regions. Our hypothesis is that a regionally downscaled projection
for the east coast of the US can be used to evaluate the ability of the existing observational
network to detect changes in ocean acidification relevant stressors for scallops and propose a
process-based strategy for the network moving forward.
Coastal Maine supports valuable lobster, clam, oyster and other shellfish industries that comprise >90% of Maine’s record $616M landed value last year. Earlier monitoring efforts in Maine and New Hampshire have documented periods of unusually acidic conditions in subsurface waters of Maine’s estuaries, which may be driven by episodic influxes of waters from the Gulf’s nutrient-rich, highly productive coastal current system. Sources of acidity to the estuaries also include the atmosphere, freshwater fluxes, and local eutrophication processes, all modulated by variability imparted by a number of processes.This project is a data synthesis effort to look at long-term trends in water quality data to identify the key drivers of acidification in this area. Extensive data sets dating back to the 1980s (including carbonate system, hydrography, oxygen, nutrients, and other environmental variables) will be assembled, subjected to QA/QC, and analyzed to assess acidification events in the context of landward, seaward and direct atmospheric sources, as may be related to processes operating on tidal to decadal timescales. Such analyses are requisite for any future vulnerability assessments of fishery-dependent communities in Maine and New Hampshire to the effects of coastal acidification.