Ocean acidification in the Gulf of Maine: NHSG's response to an emerging environmental concern

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For most of the last 100 years, chemical oceanographers believed that the natural balance provided by the carbonate buffer system in the ocean would keep the pH in the ocean – a measure of the hydrogen ion concentration or acidity – within a very tight range supportive of the organisms that require carbonate – the ion CO3 – to make their shells and skeletons.

Carbon dioxide (CO2) concentrations in the atmosphere have been increasing in recent years, primarily due to human emissions of fossil fuel CO2. This atmospheric CO2 diffuses into surface ocean waters, leading to an increase in CO2 concentrations in in the oceans over the past decade. This has shifted the balance of the carbonate buffer system and resulting in the lowering of pH – a higher hydrogen ion concentration often referred to as acidification. Ocean acidification (OA) is a global-scale process originating primarily in the more industrialized Northern Hemisphere. The Gulf of Maine also has some regional and local characteristics, including large discharges of freshwater from rivers entering the Gulf and waters that flow south from the Gulf of Saint Lawrence that introduce more acidic waters.

Visual description of ocean acidification via chemical reactions.

Graphic above courtesy of Chris Gobler, Stony Brook University.

Small increases in the acidity of ocean water do not have a direct effect on human health. However, for many of the organisms that make up the complex and productive food web of the Gulf of Maine that sustain important fisheries, increased acidity can have severe impacts on the growth of carbonate-dependent species such as shellfish, finfish, and corals. Of particular concern are the very young larval stages of these organisms both in the wild and in aquaculture operations.

The OA process outlined above touches on all of the strategic focus areas of N.H. Sea Grant, including healthy coastal ecosystems, sustainable fisheries and aquaculture and hazard resilient coastal communities and economies and thus has become an issue for research, extension and education initiatives. Working with local, state and federal partners through the Northeast Coastal Acidification Network (NECAN) to define crucial research gaps in our understanding of the impacts of OA on critical species, N.H. Sea Grant has invested in a number of initiatives designed to provide information to assist local aquaculture business and fishermen in understanding and responding to coastal and ocean acidification.

Close-up of clam shells

For example, N.H. Sea Grant has invested locally to determine the interactive effects of temperature and OA on viral loading and the onset of leukemia in softshell clams. An information sheet has been developed to further explain the clam leukemia research taking place at UNH. N.H. Sea Grant-funded researchers are also investigating the effects of OA on marine mussels through the use of genetic sequencing. Preliminary results from another research project funded by N.H. Sea Grant indicates that OA might interfere with lobsters’ olfactory-related behaviors.

N.H. Sea Grant has also developed an educational curriculum to address ocean acidification as part of the newly updated Climate Change SeaTrek Program offered by the UNH Marine Docents. Starting in fall 2016, the program aims to help students in grades 4-8 and adults to improve their understanding of the basic concepts of climate change and ocean acidification, with a focus on local impacts for the adult audiences.

In addition, the Northeast Sea Grant Consortium (which includes the Sea Grant Programs from Maine, N.H., MIT, Woods Hole, Rhode Island, Connecticut and New York) has partnered with the National Oceanographic and Atmospheric Administration (NOAA) to fund four OA-related research projects beginning in 2016. The projects focus on:

  • Identifying OA resilience traits in oysters, quahogs and blue mussels for developing resistant varieties
  • Getting more detailed information on field resilience of blue mussels to OA stress and using that i formation to both breed resilient populations and to define environmental conditions conducive to the development of resilience
  • Looking at the effects of OA and ocean warming on critical early life stages of the American lobster
  • Determining the sensitivity of a key forage species — the sand lance — in the Gulf of Maine to OA and other associated stressors

Ocean acidification is an emerging environmental concern in the Gulf of Maine and beyond, and Sea Grant is working closely with its partners to address OA-related challenges through various research, education and outreach efforts.

For more information about N.H. Sea Grant's research efforts regarding OA, please contact Steve Jones at stephen.jones@unh.edu or 603.862.5124.