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Continuous Monitoring Station

Imagine Working 365 Days a Year.

Friends of Casco Bay is doing just that, using technology in our Continuous Monitoring Station. The station consists of a data sonde, an instrument that can measure several properties of water at once, and a separate device that measures carbon dioxide. These electronic devices are secured together in a repurposed lobster trap on the ocean floor. The monitors collect data once an hour, every hour, year round.

Understanding a Changing Casco Bay

The flow of hourly data that our Continuous Monitoring Station collects helps us detect and document how climate changes and other emerging coastal stressors may (or may not) be affecting Casco Bay. The amount of data collected—high frequency data—allows us to statistically “crunch” the numbers with better levels of scientific veracity than simply taking the occasional snapshot of conditions. While the snapshots are also important for monitoring the health of the Bay, this hourly data set can help us identify daily, seasonal, and annual trends and better assess the extent to which ocean acidification may be impacting the water chemistry of the Bay.

By deploying the date sonde and carbon dioxide sensor, we are able to collect hourly data on temperature, salinity, dissolved oxygen, pH, chlorophyll, and carbon dioxide (partial pressure). While vital in and of themselves, these measurements can also be used to calculate additional parameters, such as alkalinity, dissolved inorganic carbon, and calcium carbonate saturation state. By looking at these additional, calculated parameters, we get a more complete picture of acidification in the Bay. When we check the station to download data and swap out the equipment with freshly calibrated sensors, we also measure the color of the water, as well as Secchi depth, we collect nutrient samples for lab analysis, and we note marine critters (including invasive species) present in the trap.

This station, located off Yarmouth near the coastal midpoint of Casco Bay, was launched in 2016. Long-term data sets, collected hourly, are proving indispensable to monitoring the changing health of Casco Bay.

What We Are Learning

Research Associate Mike Doan nicknamed our monitoring station “the cage of science.” Having more data on carbon dioxide, which has an impact on the acidity of our coastal waters, not only supports our advocacy and education efforts, but also informs the work of other scientists, government officials, and activists working to protect the health of Casco Bay.

Periodically, we post findings and updates, based on data from the station, which you can find below.

More from our Continuous Monitoring Station

Water Temperatures Are Changing in Casco Bay

November 13, 2018

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… Read more

See sea critters and our Cage of Science

August 24, 2018

Watch this short video about the Cage of Science! 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… Read more

Spring Blooms in Casco Bay

June 26, 2018

What signs tell you that spring has arrived? Grass turning green? A robin in your yard? Ospreys returning to their nests? What about huge blooms of phytoplankton in Casco Bay? The chlorophyll fluorescence measurements in the graph above were recorded by our Continuous Monitoring Station, which has been in place… Read more

The Care and Maintenance of Our Submerged Monitors

Research Associate Mike Doan prepares our Continuous Monitoring Station for cleaning and re-calibration.

The only way to collect reliable data is to employ impeccable data collection methods. To that end, Mike swaps out the data sonde with freshly calibrated sensors, on a rigorously adhered to schedule. Our goal is to be able to capture 8,760 hourly data sets each year, or as close to that as equipment conditions allow.

Mike hauls up the anchored cage of devices and uploads to his laptop the data from the carbon dioxide sensor. He scrapes off marine hitchhikers, such as sea stars, tunicates, and algae, and makes note of any invasive species attached to the equipment or the cage. He often exclaims “It is amazing how fast sea creatures occupy any available surface under water, including our instruments!”

He swaps the data sonde for the one with freshly calibrated sensors, and checking to make sure the devices are secured, he then lowers the cage back onto the ocean floor. The retrieved data sonde is brought back to our lab, the data is downloaded and housed, and the sonde and its sensors are cleaned, soon to be re-calibrated for re-deployment. Such attention to detail provide quality assurance about the accuracy of the data.