Research Associate Mike Doan is often asked, “What were the highest and the lowest water temperatures this year?” Thanks to our Continuous Monitoring Station, Mike is able to share those with confidence. Mike can tell you about water conditions in the Bay on an hourly, daily, weekly, seasonal, or yearly basis, in far more detail than ever before. “Along with identifying temperature extremes, we are interested in being able to monitor how seasons are shifting as Casco Bay continues warming. For example, we are looking at how many days a year the daily average temperature rises above 15°C [59°F] and falls below 5°C [41°F]. In 2018, we had 103 days above 15°C, compared to 97 days in 2017.”
Observes Mike, “2019 is on track to be as warm as 2018 was. With only three years of continuous data, it is much too early to call this a ‘trend,’ but these measurements support our concern that Casco Bay is getting warmer.” Temperature influences how much oxygen and carbon dioxide the water can hold, the rate of plant growth and decay, the movement of currents, and the geographic distribution of marine life. Friends of Casco Bay’s Continuous Monitoring Station has been amassing hourly data on the health of the Bay since July 20, 2016. This “Cage of Science” consists of a modified lobster trap that houses a data sonde and a carbon dioxide sensor. It is funded, in part, by Casco Bay Estuary Partnership and other generous donors. We post the data on our website at cascobay.org/continuous-monitoring-station, where anyone can check out ten parameters that tell us about conditions in Casco Bay.
The Continuous Monitoring Station is anchored just above the ocean floor in Yarmouth. This location was chosen because it is near the coastal midpoint of Casco Bay. We look forward to installing additional monitoring stations at opposite ends of the Bay, near Portland Harbor and in eastern Casco Bay. By establishing an array of three stations, we will be able to understand the variability and change in the eastern, middle, and western regions of the Bay. Says Executive Director Cathy Ramsdell, “We do not collect data merely for the sake of collecting data. The science is used for informing our advocacy and education efforts. What we are learning from our Cage of Science can help our communities understand that conditions are changing, and together we can explore possible responses.”
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.
Friends of Casco Bay’s newest workhorse—our Continuous Monitoring Station (CMS)—has been amassing hourly data on the health of the Bay for over two years now.
Research Associate Mike Doan is excited to be able to look at the daily, weekly, and seasonal changes in the Bay in far more detail than ever before. Mike was able to make comparisons between the first two years of data, comparisons we will continue tracking year to year. For example, the graph above shows nuances we could not have documented before:
A. The period of late summer-early fall of 2016 was warmer than the same time period in 2017.
B. The winter of 2017-18 turned colder earlier, with water temperatures dropping below 0°C before the end of December. In the previous winter, water temperatures did not drop below 0°C until late January.
C. Overall, spring and summer of 2018 were warmer than the same periods the year before.
On July 20, 2018, we marked the second anniversary of when our Continuous Monitoring Station began recording data off Yarmouth near the coastal midpoint of Casco Bay. The data are providing insights into how climate change and ocean acidification may be affecting the health of our waters.
The Station consists of a modified lobster trap that houses a data sonde and a carbon dioxide sensor, instruments that collect data on many different aspects of water conditions.
Mike is the architect of our Cage of Science. “It’s been a lot of work to get to this point,” admits Mike, “and it is exciting to see the quality and quantity of data we are collecting.” Colleagues have taken notice of how he has been able to outfit an electronic station with accurate, high-tech monitoring equipment at reasonable cost. Several scientists already are using the continuous data.
We look forward to building the long-term data set that will provide a more complete picture of a changing Casco Bay, information that can help our communities assess, mitigate, and adapt to those changes.
Why is water temperature important?
Temperature influences how much oxygen and carbon dioxide the water can hold, the rate of plant growth and decay, and the movement of currents. Temperatures also impact the geographic distribution of marine life. Menhaden (pogies), typically found in the mid-Atlantic, have been showing up in large numbers in Casco Bay. Lobstermen say that lobsters are remaining farther offshore, with fewer showing up in warmer water areas around inshore eelgrass beds. We are seeing species of phytoplankton that were never before documented in Casco Bay.
Thanks to support from Casco Bay Estuary Partnership and generous donors, our Continuous Monitoring Station collects data once an hour, every hour, year round.