Ocean acidification a threat to clams, other marine life

In a January 26 presentation at the Wessaweskeag Historical Society in South Thomaston, Jon Eaton of the Georges River Tidewater Association talked about the importance of measuring for acidity in local rivers. Marine biologists and fishermen alike fear increased acidity in the ocean will lead to corrosion of shells on clams, oysters and other sea organisms. Eaton is seeking volunteers to take water samples along the St. George River estuary, and said he would like to help with sampling efforts along the Medomak and Weskeag Rivers, as well.

Sherman Hoyt, fisheries outreach coordinator for the Maine Sea Grant at the University of Maine Cooperative Extension, joined Eaton to share his concerns for the future of shellfish and other marine life in midcoast rivers.

The presentation, hosted by a South Thomaston environmental group called Friends of the Weskeag, introduced plans for a shoreline water monitoring program this spring. “Citizen scientists” will have the chance to measure pH, nitrogen, chlorophyll, turbidity, temperature and salinity in the St. George River estuary, 12 miles northeast of Muscongus Bay.

According to a Working Waterfront article by Island Institute’s Dr. Heather Deese and Catherine Schmitt of the Maine Sea Grant, increased levels of carbon dioxide in the Earth’s atmosphere have led to ocean acidification.

Their article explains that as carbon dioxide is absorbed into the ocean it forms carbonic acid, “a weak acid that readily breaks apart into its components, bicarbonate and hydrogen.” These hydrogen ions have led to increased acidity in the world’s oceans.

They write that sea creatures such as clams, oysters, lobsters, urchins, coral and some species of plankton use carbonate, along with calcite and aragonite, to build their shells.

According to the article, the combination of hydrogen and carbon takes carbonate away from the sea creatures that need it to build their shells. And increased acidity, combined with low carbon levels, creates a “corrosive environment” in which the shells of these sea creatures start to dissolve.

Eaton explained how the Georges River Tidewater Association has worked with local clam harvesters to monitor the river, reduce fecal contamination, and open the flats for harvesting.

Hoyt credited the improvements to the health of the clamming harvests along the St. George River to the water quality monitoring efforts and significant advocacy work of the Association. Hoyt worked with the Georges River clammers in the mid-1990s to bring the fishery back to life.

This work realized significantly improved results, Eaton said, but people have lately become concerned about lower pH values (higher acidity) in ocean water. On the pH scale, neutral pH is 7, but ocean water pH is normally 8. Eaton said even a one-tenth of a unit change in that scale will have huge implications for marine organisms.

Eaton referenced research being conducted in Casco Bay by Dr. Mark Green at St. Joseph’s College in Standish. He said their research found that clam larvae (also called “spat”) will not settle on muds with low pH, even at levels above neutral. Eaton also mentioned a presentation by Dr. Joe Salisbury, an oceanographer with the University of New Hampshire, who attended the 2011 Fishermen’s Forum in Rockland. He said Salisbury’s research showed that the pH value of open ocean water is falling by 0.125 units every 50 years, which if the same were to happen in a human, could lead to coma and death.

According to an article in Spheres, an electronic newsletter put out by UNH Institute for the Study of Earth, Oceans and Space, Dr. Salisbury was a co-investigator on NOAA’s Gulf Challenger measuring the effects of carbon dioxide on sea creatures. NOAA has several buoys measuring carbon dioxide levels in the ocean, one of which is north of Appledore Island in the Gulf of Maine.

Eaton said the water quality parameters the Department of Environmental Protection is concerned about are pH, dissolved oxygen and nitrogen. He said nitrogen is a nutrient and causes algae blooms in shoreline water, which then absorbs oxygen as it decomposes.

“Those are the three factors we are going to start monitoring for this coming summer,” he said, adding that the DEP is anxious to work with citizen scientists and plans for the monitoring project.

“What we’re very concerned about is can we make it sustainable?” Eaton said. “I think if we can broaden it geographically, and get volunteers from neighboring estuaries…to get interested in this, we can broaden the footing and make this more sustainable.”

Eaton said they will need at least 16 volunteers for water monitoring on the St. George River. They have eight boat stations and eight shore sample stations. They will have a volunteer recruitment day on March 10, with a training day at the end of March. Volunteers will use a pH meter, an oxygen measuring device, a hydrometer or other equipment to measure salinity, and vials to collect samples to measure total nitrogen.

Eaton said the Association has eight kits that cost $323 each. As an alternative to volunteering at one of the monitoring stations, individuals who want to take measurements off their own dock can buy a kit and go through the training offered through the Association. Eaton said people along the Weskeag River or Medomak River could do the same, and give the water samples that are collected over to the Association so they can be tested.

Interested parties can contact Jon Eaton at 354-2234, or email jonathan.eaton@gmail.com.

John Maguire, The Coastal Journal, 2 February 2012, Article.

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