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Decades of Data: A Watershed Year for Science

This year we are marking two important milestones: our 30th season of monitoring the water quality of Casco Bay and the first full-year of having three Continuous Monitoring Stations in the water.

Staff Scientist Mike Doan says that both our Seasonal Sampling and Continuous Monitoring efforts are crucial to our mission to protect the health of the Bay. “Casco Bay covers more than 200 square miles of water,” he explains. “Our monitoring programs are designed to efficiently measure how healthy various parts of the Bay are while tracking how our waters are changing over time.”

“We are proud to say that we have stuck with science for the long-haul,” says Will Everitt, Executive Director of Friends of Casco Bay. “It takes tenacity to stick with any long-term project. It takes committed supporters and donors to ensure that we have the resources to continue this work year in and year out. If you are one of those supporters, thank you. You’ve helped us reach these milestones.”

The Casco Bay Estuary Partnership (CBEP), one of 28 federal National Estuary Programs, is among the many entities that put our data to use. “For three decades, Friends of Casco Bay’s monitoring efforts have provided a crucial part of the data used to understand the condition of Casco Bay,” says Curtis Bohlen, Director of CBEP. “The data are relied on by scientists and regulators alike. Friends’ thirty year history of monitoring the Bay provides a long term perspective crucial for understanding how the Bay is — and is not — changing.”

30 Years of Seasonal Sampling

Our Seasonal Sampling program continues to add to one of the most-important and long-term marine water quality data sets in New England. Data from this program helped to designate Casco Bay as a Federal No Discharge Area and upgrade Clean Water Act classifications for large areas of the Bay, ensuring our waters are better protected for years to come.

From May to October, Staff Scientist Mike Doan and Casco Baykeeper Ivy Frignoca take to our Baykeeper boat or truck and travel to 22 sites across the Bay.

“We are providing a health check-up for the Bay each day we are out there,” Mike explains. “Like a doctor checking your blood pressure, if we find an anomaly or problem, we can do more thorough investigations.”

365 Days of Continuous Data

Mike and Ivy use a scientific device that measures water quality characteristics called a data sonde to measure temperature, dissolved oxygen, pH, salinity, chlorophyll, turbidity, and water depth. They also collect water samples that we send to a laboratory to measure total nitrogen.

As of May 20, 2022, Friends has a full year of around-the-clock data from all three of our Continuous Monitoring Stations. In May 2021, we launched two new Continuous Monitoring Stations in Casco Bay, located off Harpswell to the east and in Portland Harbor to the west. These two Stations joined our original station off the coast of Yarmouth, near the coastal center of the Bay, first launched in 2016.

Mike designed our Continuous Monitoring Stations, which combine a data sonde with a sensor that collects carbon dioxide data. “We launched the stations to measure how the Bay is changing,” says Mike. “By looking at data collected every hour on the hour, we can better see through the noise of daily and seasonal changes, and understand how climate change may be impacting our waters. Having three stations up and running for more than a year now is giving us a clearer picture of what is happening in very different regions of the Bay.”

Our Continuous Monitoring Stations are maintained thanks to the generous support of the Casco Bay Estuary Partnership and the more than 700 Friends of the Bay who gave to our Climate Change and Casco Bay Fund.

New data, NEW insight

Presenting data is like telling a story. When we look at a graph of our water quality data, it tells us a story about the health of Casco Bay. Seeing the same data in a different kind of graph can help us see another perspective, another side of the story. 

This graph compares 2022 daily mean temperatures (the blue line) to historic temperature data (the gray line and shaded area) from our Yarmouth Continuous Monitoring Station. Additional graphs in this style for other water quality data — including dissolved oxygen, pH, salinity, and more —   recorded at our Yarmouth station can be found here. 

Staff Scientist Mike Doan is using a new kind of graph to present data from our Continuous Monitoring Station in Yarmouth. “This style of graph is one that climate scientists like to use to present long term data sets,” says Mike. “Using it helps us compare data from a single year to the historic range of conditions we’ve seen at our Yarmouth station.” 

The Yarmouth station is one of our three Continuous Monitoring Stations in Casco Bay. These stations use high-tech oceanographic equipment to collect data on multiple water quality parameters and help us assess how the Bay may be changing. Our stations located off Harpswell and in Portland Harbor were launched last spring. Our Yarmouth station was launched in 2016. With over six years of data from that station, we can compare data from a specific year to the historic range of conditions we have recorded there.  

To illustrate this point and get us all thinking about what these data can reveal about the health of Casco Bay, consider the graph below and the information it presents.

This graph compares 2021 daily mean temperatures to historic temperature data recorded at our Yarmouth Continuous Monitoring Station. 

Daily Means 2021: the green line represents the mean water temperature at the Yarmouth station for every day in 2021. A “mean” is just another word for an average.

Daily Means 2016 – 2021: the dark gray line represents the mean water temperature at the Yarmouth station for every day between 2016 – 2021. In other words, this dark gray line represents the daily average water temperature over the past six years. 

Range of Daily Means 2016 – 2021: The gray shaded area represents the range of daily mean water temperatures at the Yarmouth station between 2016 – 2021. It helps us to visualize the difference between the highest and lowest daily average temperature recorded at the station. The top of the gray shaded area represents the highest daily average temperature and the bottom represents the lowest daily average temperature recorded on any given day over the past six years. 

Mike says that 2021 was one of the hottest years we have seen at the Yarmouth station. “This graph shows us just how hot the year was. We can see that for much of 2021, the green line is close to the top of our historical range of temperature values,” explains Mike. “In the context of the past six years, 2021 was a particularly warm year for the Bay.”

What do you see in these new graphs?

Let us know by emailing keeper [at] cascobay [dot] org and visit this page of our website to see our latest data on salinity, dissolved oxygen, pH, and other parameters from the Yarmouth station presented in this new style of graph.

How does something so tiny drive change in the Bay?

What factors drive seasonal changes in the waters of Casco Bay?

Staff Scientist Mike Doan addresses this question by looking at recent data from our Continuous Monitoring Stations in our latest Mike’s Field Notes video.

Our Continuous Monitoring Stations collect data hourly on a variety of key water quality and climate change indicators across Casco Bay. Understanding the ways that climate change is impacting the Bay requires many years of data. As we work to collect these long-term data sets, we need to become familiar with the factors that drive short-term changes in water quality. These short-term changes may occur between seasons, months, or even day-to-day.

The activity of phytoplankton – the microscopic plants at the base of the marine food web – is one factor that influences many of the parameters we track in our Continuous Monitoring data. In this video, Mike breaks down how phytoplankton can influence acidity, as well as the amounts of carbon dioxide and oxygen in Casco Bay.

As always, you can view our Continuous Monitoring Station data on our website.

Thank you for caring about the health of Casco Bay.

Join us: new stations, a celebration, and data!

As spring settles on Casco Bay, ospreys return to their nests, and alewives leave the sea and swim upriver to spawn in freshwater.

The arrival of spring has always brought seasonal shifts to Casco Bay, but today climate change and human influences are impacting our coastal waters at a scale and pace we do not fully understand. That is why we are expanding our array of Continuous Monitoring Stations to monitor changing conditions in three regions of Casco Bay, every hour of every day, 365 days a year.

In March, we launched a new Continuous Monitoring Station in Harpswell’s Cundys Harbor to track conditions unique to the embayments and coves of eastern Casco Bay. Today, we launched our Portland Harbor Station to monitor water quality in the Bay’s busiest and most populated region. These two new Stations join our original Continuous Monitoring Station located at the coastal center of the Bay off Yarmouth.

To commemorate the launch of our two new Stations and the completion of the Climate Change and Casco Bay Fund that is making this all possible, please join us for an online Casco Bay Matters event to celebrate! On Wednesday, June 16, from 5:30-6:15 p.m., Staff Scientist Mike Doan will share and compare, for the first time, data from all three Continuous Monitoring Stations.

Register Now

Mike will be joined by Executive Director Cathy Ramsdell and Casco Baykeeper Ivy Frignoca to discuss how these new stations will enhance our advocacy on behalf of Casco Bay for years to come.

We hope you can join us!

What: Celebrating Data From Our New Continuous Monitoring Stations — A Casco Bay Matters Event

When: Wednesday, June 16, from 5:30-6:15 p.m.

Please register to attend this online event.

Register Now

Spring Blooms in Casco Bay

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 for almost two years.

Chlorophyll fluorescence is a measure that provides an estimate of phytoplankton abundance. Chlorophyll is the green pigment in plants that traps the energy of the sun for photosynthesis.

The graph tells us that this year’s spring bloom of phytoplankton started around the same time as last year, but was bigger in magnitude this year than in 2017.

Why do we care about chlorophyll levels? Phytoplankton are the single-celled plants that make up the foundation of the ocean food web. Phytoplankton also provide half of all the oxygen we breath—so thank phytoplankton for every other breathe you take. You can read more about phytoplankton and chlorophyll in our recent post.

Photography by Kevin Morris

Every hour and every day, the Continuous Monitoring Station—a.k.a our “Cage of Science”—is building a more complete picture of the seasons beneath the Bay. Thanks to support from Casco Bay Estuary Partnership and generous donors, the Station collects measurements of temperature, salinity, pH, dissolved oxygen, carbon dioxide, and chlorophyll fluorescence year-round. Every other week, Research Associate Mike Doan cleans and calibrates the equipment, and downloads and graphs the data to track conditions in the Bay.