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Temperature Extremes

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.”