With increasing research showing that coastal acidification is a threat to Casco Bay, here’s what we’re doing about it.
Why do scientists and sea farmers worry about acidifying seawater? Studies by researcher Dr. Mark Green and oyster grower Bill Mook have found that increasing the acidity of seawater can stress sea creatures such as clams, oysters, and mussels. Some shellfish farmers in Maine have already begun storing seawater to use during times when stormwater runoff makes the water unsafe for developing oysters.
Climate researchers have found that the ocean absorbs over 25% of the carbon dioxide released into the atmosphere by smokestacks and tailpipes. This is called ocean acidification. In addition, carbon dioxide ends up in coastal waters from nitrogen pollution from fertilizers, pet wastes, stormwater runoff, and sewage discharges. This nitrogen overdose stimulates a population explosion of tiny phytoplankton. When these plants die and decay in bays and coves, bacteria consume oxygen and release carbon dioxide. This creates even more acidic conditions for coastal critters. This is called coastal acidification.
Dr. Mark Green of St. Joseph’s College in Standish, Maine, is a leading researcher on the impact of coastal acidification on clams. He has been testing how baby clams respond to mud from clam flats along our coast, including Casco Bay. He calls clams the “canaries in the coal mine.” Nitrogen runoff, he asserts, is hampering the ability of clams and oysters to build and maintain their shells. Dr. Green found that clam spat and baby clams simply dissolve at levels of acidity found in some parts of Casco Bay today. He calls this unfortunate condition “death by dissolution.”
Dr. Green’s experiments in the lab inspired us to investigate conditions in Casco Bay. In 2011, we sampled the pH (acidity) of the mud on about 30 clam flats around Casco Bay. In 2012 and 3013, we returned to one of those clam flats to monitor conditions every two weeks across three seasons and varied tide cycles to get a better understanding of how natural fluctuations impacted pH. We also put baby clams (spat) into “clam condos” into a clam flat in Freeport, protected from green clams by screens. After one week and two weeks in the mud, we found significant pitting in their shells, indicating that the shells were dissolving.
Coastal Acidification is one more stressor for shellfish species that already are challenged by other climate change impacts, such as predation by gluttonous milky ribbon worms and green crabs which flourish in warming waters. Red tides or other harmful algal blooms may close clam flats to shellfish harvesting for weeks or months each year. The density and duration of these harmful bloom events may be exacerbated by nitrogen runoff, which provides the nutrients to nourish the red tide organisms.
What are we doing about coastal acidification?
The good news is that we can do something to fight back against coastal acidification caused by nitrogen pollution. Says Casco Baykeeper Ivy Frignoca, “It’s wonderful to work with so many scientists, harvesters, and policy makers who understand this issue and are working on it before coastal acidification becomes insurmountable.”
One way is to find out what we know and what we need to know about coastal and ocean acidification. Friends of Casco Bay and others realized we need a concerted effort to fight the effects of ocean and coastal acidification. In 2014, we participated in the Maine Ocean Acidification Study Commission, which issued a report to the Legislature in January 2015, recommending many actions to confront this threat to our fisheries and marine ecology in general, including establishing an on-going ocean and coastal acidification council.
Friends of Casco Bay worked with the Island Institute and University of Maine/Maine Sea Grant to create the Maine Ocean and Coastal Acidification Partnership (MOCA). MOCA volunteers partnership seek to:
- Implement recommendations of the Ocean Acidification Study Commission; and
- Coordinate the work of governmental agencies, private organizations, and citizens who are studying and implementing means to reduce the impacts of or help adapt to ocean and coastal acidification.
Here are some highlights of MOCA:
March 14, 2016
MOCA held its first meeting, attended by more than 30 scientists, policy makers, and harvesters.
June 29, 2016
MOCA hosted a day-long Ocean Acidification Symposium, attended by 110 people, including some of the state’s top researchers and policy makers. Scientists shared their field experiment data and compared notes.
November 16, 2016
MOCA hosted a second symposium focused on remediation and policy. More than 50 people gathered at the State House in Augusta to discuss the possibility of developing state/ federal water quality criteria related to coastal acidification. Ivy discussed how we might use existing regulatory tools to reduce nitrogen pollution that exacerbates coastal acidification. The participants formed subcommittees to create an action plan on next steps for confronting ocean acidification through research and legislation.
- Education Casco Baykeeper Ivy Frignoca is working with the MOCA Policy Subcommittee to help organize two MOCA symposia in 2017. They will educate interested citizens and decision makers on cutting-edge science and local and state policies that may be implemented to combat acidification
- Uniform data collection is the goal of Friends of Casco Bay Research Associate Mike Doan and more than a dozen other scientists on the MOCA Monitoring Subcommittee. They will work together to coordinate and standardize monitoring equipment and procedures on data collection on acidification. This uniformity will provide better understanding of nitrogen inputs into coastal waters.
What can you do about coastal acidification?
- Cut down or eliminate fertilizers on lawns, gardens, and farms.
- Lobby for and support a town ordinance to limit the use of nitrogen-rich fertilizers.
- Reduce rainwater runoff and improve sewage treatment.
- Make sure septic systems are doing their job.
- Join and/or volunteer with organizations to monitor coastal waters and educate the public.
- Reduce carbon emissions by driving less or driving a less polluting vehicle
- Support clean energy production such as solar and wind power
- Support clean energy policies such as RGGI and the Clean Power Plan