Living close to the ocean, Casco Bay residents are witnessing the effects of climate change happening here now: warming water temperatures, increasing ocean acidity, and more severe storms. We too are seeing the changes in our data and when we are out on the Bay.
From April through October, our Research Associate Mike Doan and Casco Baykeeper Ivy Frignoca are on the Bay frequently to monitor water quality, follow up on pollution reports, or meet with partners on issues best understood from the water. Their vigilance gives them a firsthand view of changes happening in our coastal waters.
Mike, Ivy, and Executive Director Cathy Ramsdell shared these and other observations in our first-ever Casco Bay Matters series. Nearly 400 people attended Ocean Acidification, Climate Change and You presentations about what we are learning about a changing Casco Bay.
They shared how Mainers are working together to shape policies and actions to respond to these threats. Ivy is coordinating the Maine Ocean and Coastal Acidification partnership, a diverse coalition of scientists, lawmakers, aquaculturalists, and seafood harvesters, who collaborate on research and strategies to confront the threats that climate change and acidification pose to Maine’s marine resources. We also are working with legislators to pass a bill to create a state-sponsored Science and Policy Advisory Council on the Impact of Climate Change on Maine’s Marine Species.
Video Recordings of Casco Bay Matters:
If you missed our Casco Bay Matters presentations of Ocean Acidification, Climate Change and You, you are in luck — our stalwart volunteer Deb Dawson recorded and edited videos of our South Portland (March 25, 2019) event. See the series of three videos on our YouTube channel.
Highlights from Casco Bay Matters:
Warmer waters: Friends of Casco Bay has been tracking water temperatures for over a quarter century. On average, water temperatures in Casco Bay have risen 2.5°F (1.4°C) since 1993. The growth, reproduction, and survival of marine life are influenced by temperature.
More carbon dioxide in our coastal waters from air and from land: We know that burning fossil fuels adds carbon dioxide to the atmosphere, trapping heat and warming the planet. Nearly 30% of atmospheric carbon dioxide is absorbed by the ocean. Carbon dioxide mixes with water to form carbonic acid, making the water more acidic. This is ocean acidification.
Maine’s nearshore waters are also at risk from coastal acidification. Excess nitrogen from sewage treatment plants, polluted stormwater, and fertilizers can stimulate massive algal growth. When the algal blooms die, decomposition depletes the area of lifegiving oxygen and releases carbon dioxide, further acidifying the water.
Threats to the ocean food web: More carbon dioxide in our waters means less shell-building material (calcium carbonate) for clams, mussels, and planktonic creatures that support the ocean food chain. Data from our Continuous Monitoring Station enable us to calculate the calcium carbonate saturation state — what scientists term omega aragonite — which can tell us whether, at any given time, enough calcium carbonate is readily available to shell-building creatures. Shell formation becomes more difficult for some species when the amount of available calcium carbonate falls below a 1.5 aragonite saturation state.
Sea level rise: As water warms, it expands, and the seas encroach on our coastline. Coastal observers and property owners are reporting more erosion.
Increasing precipitation: Maine has seen a six-inch rise in average annual precipitation since 1895, further threatening coastal properties. Torrential rains intensify erosion and flush overloads of nitrogen, pollutants, and sediments into coastal waters.
Those who depend upon the sea can attest to the fast pace of change. What do these changes mean for Casco Bay?
As oceans become more acidic, we can anticipate more pitting or thinning of the shells of many commercially viable species in Casco Bay, such as clams, mussels, and oysters.
Voracious green crabs — which eat juvenile shellfish — thrive in warming waters.
Rising water temperatures are linked with shell disease in crustaceans, directly impacting Maine’s iconic lobster fishery.
Scientists and lobstermen are documenting lobster populations shifting north and east.
Copepods, tiny crustaceans that are the main food source for juvenile lobsters, may not be as plump as they once were. In laboratory experiments that simulate climate changes now happening in the Gulf of Maine, copepods were less fatty. With a less nutritious diet, young lobsters must divert energy from growth and resisting disease to finding enough food to survive.
Committee on Environment and Natural Resources
c/o Legislative Information Office
100 State House Station
Augusta, ME 04333
Re: Friends of Casco Bay and Maine Ocean and Coastal Acidification (MOCA) Steering Committee testimony in support (with amendments) of LD 1679: An Act To Establish the Maine Climate Change Council To Assist Maine To Mitigate, Prepare for and Adapt to Climate Change (Governor’s bill)
Dear Senator Carson, Representative Tucker, and Distinguished Members of the Environment and Natural Resources Committee,
Introduction to Support for Bill with Amendments:
Friends of Casco Bay and the Steering Committee of the Maine Ocean and Coastal Acidification (MOCA) partnership submit the below testimony in support of LD 1679, An Act To Establish the Maine Climate Change Council To Assist Maine To Mitigate, Prepare for and Adapt to Climate Change (Governor’s bill). We support the bill but recommend four amendments to better address the impacts of climate change to Maine’s marine species and habitats. These amendments are set forth in the attached track-changes document and below:
Amend Section 11 (38 MRSA § 578) – which requires the Council or Department to provide evaluation reports to this Committee and the Energy, Utilities and Technology (EUT) Committee – to also require reports to the Marine Resources Committee (MRC) and to authorize the MRC to make recommendations to this Committee.
Amend Section 10 (38 MRSA §577-A) (8) to include recommendations for scientific monitoring and research to fill data gaps needed to spur action or evaluate remediation and adaptation strategies.
Amend Section 10 (38 MRSA §577-A) (6) to specify that the Scientific Subcommittee should provide technical support to the working groups and should contemplate creating subgroups of experts to support the working groups.
Amend Section 10 (38 MRSA §577-A) (1) to include representation by a fisherman and by an aquaculturist.
Who We are:
Friends of Casco Bay is a nonprofit marine stewardship organization dedicated to improving and protecting the environmental health of Casco Bay. We scientifically monitor and assess water quality, including parameters indicative of climate change and ocean acidification. We employ a Casco Baykeeper, who serves as the lead advocate, or eyes, ears and voice of the Bay. We engage in significant public outreach including citizen science and other actions to engage our members and volunteers in our work to improve the health of the Bay.1
Maine Ocean and Coastal Acidification (MOCA) is a voluntary partnership formed to implement recommendations of the Ocean Acidification Study Commission authorized by the 126th Legislature (see study commission’s report).2
Friends of Casco Bay, the Island Institute, and Maine Sea Grant convened MOCA when the State failed to establish an on-going council to implement the Study Commission’s recommendations. Friends of Casco Bay has served on the MOCA Steering Committee since its inception and as its Coordinator for the last two years. MOCA has been most effective as an interim forum for coordinating and sharing research among public and private entities and as an information exchange.
Testimony on the Marine Aspects of LD 1679:
We support the overall concept of working across sectors to mitigate and adapt to climate change. Because our expertise is with respect to the health of marine waters, we will confine our testimony to those aspects of the bill.
To paraphrase Governor Mills’ inaugural address, we must act now. Climate change is already impacting Maine’s fisheries and habitats:
About a third of all carbon dioxide emitted into the atmosphere is absorbed by the ocean, where it mixes with sea water to form carbonic acid and lower pH. This process is known as ocean acidification. In Casco Bay, pH has dropped from 8 to almost 7.8 from 2000-2012. The pH scale is logarithmic, meaning that a decrease of an integer value changes the concentration by tenfold. Lower pH (more acidic water) can cause mollusk shells—including clams, oysters, and mussels—to pit and dissolve.
Annual precipitation in Maine has increased six inches since 1895, and we are experiencing more intense storms that deliver excess nitrogen to marine waters. The nitrogen fuels algal and phytoplankton blooms. The blooms have immediate negative impacts on marine species. For example, we have seen thick mats of nuisance algae smother clams. In addition, as blooms die, they release carbon dioxide which mixes with sea water to form carbonic acid. This process is known as coastal acidification and also lowers the pH of our coastal waters.
The temperature of Casco Bay rose about 1 degree Celsius (2.5 degrees Fahrenheit) from 1993 to 2018. Warmer ocean temperatures mean that green crabs are not dying back over the winter. The higher populations of green crabs prey on soft-shelled clams and other mollusks. They also demolish eelgrass beds, a critical marine habitat. Rising ocean temperatures also cause shifts in species and can contribute to an increase in lobster shell disease.
In 2016, we began measuring the amount of calcium carbonate available for mollusks and other organisms to build their shells. We learned that for most of the year, there is not enough calcium carbonate in the water for shell-building.
Prior to news that Governor Mills would introduce her comprehensive Climate Change Council bill, Representative Lydia Blume worked with MOCA to draft LD 1284: An Act To Create the Science and Policy Advisory Council on the Impact of Climate Change on Maine’s Marine Species. The MRC held a hearing on that bill on April 2, about a month before the Governor’s bill was printed.
135 people from Friends of Casco Bay, MOCA, and other entities submitted testimony in support of LD 1284. No one testified against the bill. The Environmental Priorities Coalition selected the bill as a priority; industry leaders such as Mook Sea Farm and the Maine Aquaculture Association supported the bill; and leading marine research institutes, including Gulf of Maine Research Institute, Island Institute, Downeast Institute, and University of Maine, offered their support. The Ocean Conservancy‘s CEO sent a letter of support and separately authorized retired Congressman Tom Allen to appear and testify on their behalf.3
Commissioner Keliher testified and asked the MRC to delay further consideration of LD 1284 because the Governor intended to incorporate it into her bill. The MRC honored that request. We have reviewed and support LD 1679; it incorporates most of the intent of LD 1284 but fails to require progress reports to the MRC and afford opportunities for the MRC to make recommendations to this Committee.
We respectfully request that you amend the bill in that respect, and consider and address the other suggested amendments and comments on the attached track-changes document. Thank you for your attention to our testimony.
Friends of Casco Bay
The climate is changing faster than expected. Greenhouse gases, such as carbon dioxide and methane, are the culprits. The burning of fossil fuels for homes, industry, and transportation releases almost 10,000 million metric tons of carbon dioxide into the atmosphere every year. 1
Carbon dioxide is changing not only our climate, but also the chemistry of the ocean. About 30% of the carbon dioxide we release into the atmosphere is absorbed by the ocean. 2 In marine water, carbon dioxide decreases pH and increases acidity through a process known as ocean acidification.
Excess nitrogen from sewage treatment plants, polluted stormwater, and fertilizers, is also adding carbon dioxide into nearshore waters through a process known as coastal acidification. 3
Nitrogen can fertilize massive algal growth in our waters. When the algal blooms die, decomposition depletes the area of life-giving oxygen and releases carbon dioxide, acidifying the water.
The impacts of climate change are evident right here in Casco Bay
Friends of Casco Bay has been tracking water temperatures for over 25 years. On average, our data show a 2.5° F increase in water temperatures since 1993.
Sea Level Rise
As water warms, it expands, and the sea encroaches on our coastline. Coastal observers and property owners are reporting an increase in erosion.
Maine has seen a six-inch average increase in annual precipitation since 1895, further threatening coastal properties. 4
Threats to the Ocean Food Web
More carbon dioxide in our waters means there is less shell-building material (calcium carbonate) for clams, mussels and oysters, as well as for tiny critters at the base of the ocean food chain. The saturation state of calcium carbonate is a key measurement of shell-building material for many organisms. Shell formation becomes more difficult when the amount of available calcium carbonate falls below a 1.5 saturation state. 5 Our recent data indicate that for nearly half the year, levels of calcium carbonate in Casco Bay are not sufficient for shell-building.
What do these changes mean for Casco Bay?
As marine waters become more acidic, we can anticipate more pitting or dissolution of the shells of many commercially viable species in Casco Bay.
Rising water temperatures are linked with shell disease, directly impacting our lobster fishery and tourism industries.
Climate change is bad news for clams because green crabs — which eat juvenile shellfish — thrive in warming waters. 6
The distribution and populations of marine species in the Gulf of Maine are shifting. Scientists and lobstermen are documenting the shift in distribution of Maine’s iconic lobsters north and east.
Copepods are tiny crustaceans that are the main food source for juvenile lobsters. In laboratory experiments, copepods raised in conditions that simulate the climate changes occurring in the Gulf of Maine were less fatty. With a less healthful diet, young lobsters must divert energy from growth and resisting disease to finding enough food to survive. 7
What is Friends of Casco Bay doing?
We helped form the Maine Ocean and Coastal Acidification Partnership (MOCA) to coordinate climate change research and policy change work. MOCA is a diverse coalition of researchers, policy experts, lawmakers, aquaculturalists, and seafood harvesters. We are working to create an action plan for Maine to protect the health of our coastal waters.
LD 1284 has been selected by the Environmental Priorities Coalition, a group of 34 environmental organizations, as one of its five priority bills to address climate change in Maine.
Our Water Reporter volunteers are recording observations of how the Bay is changing. These observations strengthen our advocacy efforts as these reports are shared with regulators, legislators, and other decision makers, alerting them to conditions in the Bay.
What can you do?
Tell your legislators to support LD 1284 to create a science and policy advisory council to address the impacts of climate change on Maine’s marine species.
Climate change is affecting the health of Casco Bay faster than anyone could have predicted. Warming temperatures and increasing acidity threaten the ocean and the livelihoods of those who depend on the sea. Research is showing that changes in our coastal waters from climate change are putting lobstering, clamming, and aquaculture at risk.
Friends of Casco Bay invites you to attend Ocean Acidification, Climate Change, and You, a free event, open to all.
Staff scientist Mike Doan will talk about the warning signs we see in our monitoring data. Casco Baykeeper Ivy Frignoca will share some of the impacts to our marine species and how Mainers are working together to respond to these threats. They look forward to your questions following the presentation.
Healthy marine waters are vital to Maine’s economy and quality of life.This is such an important issue that we are hosting this presentation at three locations in the coming weeks: Portland, South Portland, and Brunswick.
On July 20, 2016, our Continuous Monitoring Station began recording data hourly, 365 days a year. We are excited to share the first two and half years of data, collected at our water quality monitoring site in Yarmouth, near the coastal midpoint of Casco Bay. We will update these graphs monthly, so come back often and see for yourself how Casco Bay is changing.
You may know that Friends of Casco Bay’s Continuous Monitoring Station—AKA our “Cage of Science”—gives us vital data about the health of the Bay. But did you also know that observations of what sea life is growing on and hanging out in the station also give us important information about conditions of our waters? In this video, Research Associate Mike Doan shows us some of the sea critters that visited the Cage of Science in August.
As always, Casco Baykeeper Ivy Frignoca has been on the move, working across Casco Bay, the state—and the nation—on efforts to protect the environmental health of Casco Bay.
A peek into her appointment calendar shows some of the highlights so far this year, as she continued to track Legislative issues and to comment on proposed wastewater and stormwater discharge permits that the Department of Environmental Protection issues to municipalities.
I became coordinator of the Maine Ocean and Coastal Acidification Partnership (MOCA) for 2018.
I will help coordinate research and advocacy on ocean acidification with a strong statewide network of policy makers, fishermen, shellfish growers, and scientists. This year-long role supports our work examining coastal acidification and excess nitrogen.
I invited Portland’s Water Resources Manager, Nancy Gallinaro, and Portland Water District’s Director of Wastewater Services, Scott Firmin, to travel with me to meet the new Environmental Protection Agency (EPA) Region 1 Administrator, Alexandra Dapolito Dunn. We highlighted our joint efforts to reduce nitrogen pollution, combined sewer overflows, and stormwater pollution to Casco Bay. I shared our data showing the impacts of climate change on Casco Bay.
Administrator Dunn accepted our invitation to come to Maine in June to attend a meeting of the Maine Nutrient Council, a group convened by Casco Bay Estuary Partnership. Afterward, Administrator Dunn will tour the Bay on our Baykeeper boat, a great opportunity for a close-up view of issues that threaten the water quality of Casco Bay.
I traveled to Washington, DC, at the invitation of Ocean Conservancy, to meet with our Congressional delegation and ask for full funding for the National Oceanic and Atmospheric Administration and the EPA. The measures we pressed for passed in the omnibus budget!
Back in Maine, I submitted comments opposing offshore drilling and then attended a meeting hosted by the Bureau of Ocean and Energy Management, to voice Friends of Casco Bay’s opposition to offshore drilling. I supported a resolve that was passed unanimously by our state legislature expressing its opposition to offshore drilling.
I testified at a public hearing as we worked to swiftly defeat a bill that would have practically eliminated the ability of municipalities to pass pesticide ordinances. If you contacted legislators after receiving our email alert about this issue, thank you! The bill was defeated!
I traveled to New Hampshire to attend a meeting of experts concerned about the rise in harmful algal blooms throughout the region, so we could learn more about new species appearing in Casco Bay.
I attended a meeting in West Bath, which drew together people who live and work along the New Meadows River, to discuss how expanding efforts in aquaculture may figure into the many uses of the estuary.
Research Associate Mike Doan gave Kate Simpson and Kayla McMurray, staffers for Senator Susan Collins, a ride to our Continuous Monitoring Station in Yarmouth. I met them at our “Cage of Science” as we demonstrated how we use technology to monitor the Bay hourly, 365 days a year. We explained that though we do not receive funding directly from the EPA, the Agency has a vital role in advising state regulators on strategies to reduce pollution, funding other research, and enforcing the Clean Water Act. This work helps us all protect the environmental health of Casco Bay.
The Maine Ocean and Coastal Acidification Partnership (MOCA) is a volunteer partnership that seeks to coordinate the work of governmental agencies and private organizations and citizens who are studying and implementing means to reduce the impacts of or help adapt to ocean and coastal acidification.
With my colleagues in the MOCA Partnership, I hosted a workshop for nearly 60 scientists, harvesters, policy makers, and advocates on What We Know about Ocean Acidification and Maine’s Lobsters. The event at Bowdoin College featured current research on the effects of climate change on lobsters and emphasized the need for ecosystem-level, long-term studies.
As the year progresses, I look forward to continuing to keep you updated on the biggest issues affecting the health of the waters we all love.
Friends of Casco Bay has developed the Casco Bay Health Index, an easy-to-interpret, visual guide to the health of the Bay. The Index allows us to integrate data from selected water quality parameters into a single value to compare and rank each site as Good, Fair, or Poor.
By clicking here, or the image below, you can see and interact with the Health Index. The Interactive Health Index will open in a new tab. By clicking on the dots you can see more about each sampling location.
Overall, the water quality in Casco Bay is good, but there are instances when low oxygen, low pH, and murky waters are cause for concern. The 2016 Health Index reveals that over 31% of the sites are considered Poor, but more than 36% of the sites meet the Good standard.
The relative rankings were calculated by analyzing dissolved oxygen, water clarity, and pH data from shoreside sites that our volunteer Citizen Stewards monitored from 2012 to 2016. The values we chose to use were the 90th percentile of the dissolved oxygen percent saturation, the mean of the Secchi depth, and the mean of the diurnal differences in pH.
Commonly Asked Questions about the Casco Bay Health Index
What is the Casco Bay Health Index?
The Casco Bay Health Index was developed to provide a reliable, uncomplicated composite indicator of the Bay’s health, while also illustrating relative levels of eutrophication. The Index allows the scientifically-sound data collected through Friends of Casco Bay’s Water Quality Monitoring Program to be presented in a format that is easy to understand and to update.
What is the goal of the Index?
The goal of the Health Index is to present water quality information in an easy-to-understand visual format by condensing a large amount of existing data into a single score for each monitoring site. By summarizing a suite of environmental parameters into one score for each water quality monitoring site, each site can be ranked relative to one another, and trends—if there are any—can be more readily identified. This product, while quantitative in nature, should be considered a qualitative place to begin to determine environmental health. The sites are assigned colors—red, yellow or green, and are mapped to indicate the health of the waters around Casco Bay. Then we can ask: Which sites, based on the selected criteria, require a closer look? What is the relative condition of sites across a region? Are these conditions improving or degrading over time?
Where do the data for the Health Index come from?
The data used for the Health Index come from Friends of Casco Bay’s Citizen Stewards Water Quality Monitoring Program. Volunteers are well-trained using EPA-approved protocols developed by Friends of Casco Bay. They monitor specific sites and collect the data twice a day on 10 appointed Saturdays, between April and October. The Index incorporates the data for a 10-year span of time and can be updated annually by adding the most recent year’s data and eliminating the oldest. We can also look at the Index in five year increments to compare changes over time.
Which of the existing water quality parameters are most appropriate to use in the Index?
Friends of Casco Bay currently monitors five physical and chemical water quality parameters through our Citizen Stewards Water Quality Monitoring Program: temperature, salinity, dissolved oxygen (DO), Secchi depth, and pH. Of these, three have been selected for use in the Health Index—DO, Secchi depth, and pH.
Dissolved oxygen (DO) DO is expressed as Percent Saturation in order to incorporate temperature and salinity. When water holds all the oxygen it can at a given temperature and salinity, it is said to be 100% saturated. At a given site during a given sampling event, temperature and salinity are measured, and DO is measured in milligrams per liter (mg/l) and then compared with the mg/l for 100% saturation in those conditions. We look at the distribution of the Percent Saturation data; we consider the lowest 10th percentile as the worse-case conditions for a particular site. That 10th percentile threshold, expressed as a Percent Saturation number, becomes a component of the Health Index for that site.
Simply averaging all the DO data for a site might obscure the full extent of any challenged conditions. For example, if a site is eutrophic, wherein nitrogen pollution levels have resulted in a huge algal bloom, there will be large swings in DO levels between the morning and the afternoon; simply looking at the mean would obscure these swings.
Secchi depth Secchi depth is a measure of water clarity. The Index uses a mean of the data to characterize each site. Sites with more organic matter and sediments in the water will be murkier and will exhibit reduced clarity, resulting in shallower (lower) Secchi depth measurements.
pH pH is a measure of the acidity of the water. pH data exhibit tremendous variability—diurnal differences through the day and seasonal shifts through the year. The Water Quality Monitoring Program requires that measurements be collected at 7:00 a.m. and then again at 3:00 p.m. on each monitoring day. This allows for a look at the change in conditions over the course of a day. The pH at a site is influenced heavily by respiration and photosynthesis. Respiration by algae, both seaweeds and phytoplankton, adds carbon dioxide to the water, which lowers pH. Measurements collected in the early morning, at 7:00 a.m., reflect the conditions found after a night of respiration and no photosynthesis. Photosynthesis of course requires sunlight and removes carbon dioxide from the water, raising pH. By afternoon, at 3:00 p.m., pH measurements will reflect the result of photosynthesis. The change between the morning and afternoon measurements, termed the diurnal swing, can be indicative of the magnitude of respiration and photosynthesis, and, indirectly, the amount of algae in the water. Since an excessive bloom of algae is one symptom of nitrogen pollution, a large diurnal swing in pH can serve as an indicator of excess nitrogen. A small change in pH is expected in a healthy, productive coastal system, but a relatively large swing can indicate a challenged site. We calculate the difference between the morning and afternoon readings, the diurnal swing, then amass that dataset to calculate the mean for the Health Index for that site.
What ranges are most appropriate for the component parameters?
For each of the three components of the Health Index, we have defined ranges, between which we would expect to see worse-case and best-case conditions. These ranges have been defined by looking not only at data for Casco Bay, but also data from other regions, state and federal guidelines, and relevant scientific literature.
0 point value
100 point value
Percent Saturation of Dissolved Oxygen
Secchi Depth (meters)
pH (diurnal swing)
How is the Health Index score calculated?
Each of the components calculated for a given site is plotted along the scale for that parameter. We use a natural logarithm formula to determine where on the scale of 0 to 100 a particular component falls. For example, a site’s calculated 10th percentile threshold for the Percent Saturation parameter will fall between 65% and 95% at a specific point on the scale between 0 and 100. The same is done for the Secchi depth component and the diurnal swing in pH. Now we have three numbers which fall between 0 and 100. These are added together and divided by 3 to obtain the mean, which is the Health Index score for that site.
How are the final Health Index scores presented?
After each site has a Health Index score associated with it, it can be classified as Good, Fair, and Poor, determined by score thresholds. A score of 85 and above is considered “Good”, a score of 70 to 84 is “Fair”, and anything below 70 falls into the “Poor” category.
What is eutrophication?
Eutrophication occurs when too many nutrients (and occasionally other factors) fuel explosive plant growth. While nitrogen is an essential nutrient in marine systems, too much nitrogen can become a pollutant when it triggers excessive algal growth. This growth can result in low DO measurements, shallow Secchi depth readings, and wide variations in pH.
Imagine working 8,760 hours a year. Friends of Casco Bay has two water quality monitors that do just that: a datasonde, an instrument that can measure several properties of water at once, and a specialized device that only measures carbon dioxide. They are anchored together on the ocean floor in Yarmouth to collect data once an hour, every hour, year round. Appropriately, these high tech tools comprise our new Continuous Monitoring Station. These hard workers have been in place since July 2016.
Why is this hourly data vital?
The steady flow of data our Continuous Monitoring Station collects will help us detect and document how climate change and other emerging coastal stressors may (or may not) be affecting the Bay. Hourly data will help us identify daily, seasonal, and annual trends and better understand the extent to which ocean acidification may be impacting the water chemistry of Casco Bay. The station may also help us assess sea level rise. The station collects data on oxygen levels, carbon dioxide (CO2), pH (the level of acidity of the water), salinity, temperature, chlorophyll, and water depth.
In order to ensure continuous data, we have two datasondes which are swapped and refreshed every two weeks. When he arrives at the dock in Yarmouth, Research Associate Mike Doan has less than an hour to reposition the alternate datasonde so that we don’t miss any of those 8,760 hours of information.
Mike hauls up the anchored devices, uploads data from the CO2 sensor to his laptop, and scrapes off marine hitchhikers such as sea stars, tunicates, and algae. “It’s amazing how fast sea creatures occupy any available surface, including our instruments!” says Mike. Before he leaves, he replaces the datasonde with one freshly calibrated and lowers the entire Continuous Monitoring Station back onto the ocean floor. Such attention to detail provides quality assurance that the data is accurate.
While this station is busy year around, we continue to enlist volunteers to help us understand the overall health of our marine waters and to identify troubled areas of the Bay. From April to October each year, more than 90 volunteer Citizen Stewards monitor scores of shoreside sites where they measure five parameters of the surface water: pH, salinity, water temperature, water clarity, and oxygen level. If you are interested in becoming a water quality monitoring volunteer, you can learn more about the program here.
Our volunteers, staff scientists, and now our automated partners, all play a role in helping us to better understand what is going on in Casco Bay.
Thank you to funders of this project, including Casco Bay Estuary Partnership, Davis Conservation Foundation, Horizon Foundation, Schwartz Family Fund of the New Hampshire Charitable Foundation, and WEX. We also thank our Members and the many donors, local businesses, and foundations that give us operational support to do our work each year.
At the annual Labor Day clambake on Little Diamond Island, Althea and her sister Priscilla help out at the end-of-the-season event that draws the community together for a farewell to summer. While the lobsters, sweet potatoes, sausages, and corn are roasting in a fire pit outside the hundred year-old Casino, their job is to wash and de-sand freshly harvested Casco Bay clams.
Althea recalls scooping huge handfuls of clams into 8 heavy kettles to steam them for the feast. Nowadays, they have to place the clams into the pot delicately, or else the shells may end up chipped or even shattered. Althea says that the clams they buy now are smaller and more fragile than the ones she
recalls from years back.
Althea’s observations seem to correspond to observations Friends of Casco Bay has been making over the years. We are studying Coastal Acidification, the problem of increasing acidity from the ocean absorbing carbon dioxide released by the burning of fossil fuels, and, we believe, from excess nitrogen washing into coastal waters by stormwater runoff. Fertilizers, sewage discharges, and pet wastes trigger algae blooms that add excess carbon dioxide to coastal waters.
Our data shows that the acidity of Casco Bay has increased since we began our water quality monitoring program nearly 25 years ago. In 2011, we began sampling the pH (acidity) of mudflat sediments, where soft-shell clams live. We found that the mud nearest to shore was more acidic (had lower pH) than sediments further away from sources of land-based pollution. Higher acidity makes it harder for shellfish to extract calcium carbonate from their environment, the material that clams, mussels, and other mollusks need to build and strengthen their shells.
In the summer of 2014, Friends of Casco Bay installed several clam “condos” in the intertidal mudflats of Recompense Bay in Freeport. Our goal was to see what would happen when we exposed juvenile clams to acidic mud. Research Associate Mike Doan caged baby clams inside PVC tubes and left them in the mud for several days. Microscope photographs of the tiny clam spat showed that after just one week, their shells had become pitted, showing signs of dissolving.