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Water Temperatures Are Changing in Casco Bay

Our CMS allows us to identify nuances in how the Bay is changing year-to-year in far more detail than we ever could before.

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.