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Keeping up with the Casco Baykeeper

For Casco Baykeeper Ivy Frignoca, the summer has been full of moments of concern and moments of magic.

How was your summer?

Summer means being on the Bay! Staff Scientist Mike Doan and I continued to collect our seasonal data on the health of Casco Bay by land and sea. As we collected water quality data, we had the opportunity to speak with people who rely on the Bay for their livelihoods and deepened our conversations about what we were seeing and how to use our data to shape our advocacy work.

How did the pandemic affect your Baykeeping work this summer?

We kept up with water quality monitoring by limiting crew on our Baykeeper boat, R/V Joseph E. Payne, to just two of us at any one time. We continued to collect hourly data from our Continuous Monitoring Station. We kept up with all water quality monitoring, including responding to the unexpected.

What changed and what we really missed was inviting others out on the boat with us. We love using the boat as our summer office, a way to gather people who can work together to find solutions to problems that impair the health of the Bay. It makes a big difference to view issues from the water and have people aboard with expertise and authority to address problems. We couldn’t do that this year.

What was the most concerning issue you saw this summer?

What stands out was a day in mid-July when we saw a large area of brownish water extending from the mouth of the Royal River. Mike and I thought it might be a phytoplankton bloom. But when we put our sonde in the water, it measured low salinity levels that were startling, extending out almost to Moshier Island. We had captured a stormwater plume from a recent major rainstorm.

What also stands out was how uniformly high water temperatures remained this summer. Broad Cove saw temperatures near 20°C [70°F] and the upper New Meadows River had temperatures between 25-26.5°C [nearly 80°F].

What we saw this summer reaffirmed for me the urgency of our collective work to document change, reduce the causes of climate change, and prepare for its consequences at community, regional, state and national levels.

How about some of your favorite moments of the summer?

There are always moments of astounding beauty on the Bay. Every day on Casco Bay is magical. Watching terns feeding, bald eagles soaring above the boat, leaping sturgeons in a school of bait fish, or the sunlight reflecting like a mirror on the water are moments of magic that underlie why we work to protect this amazing place.

I really enjoyed becoming more deeply connected to our volunteer Water Reporters. Their posts track important issues and give us a great view of what is happening around the Bay. Working with Community Engagement Coordinator Sarah Lyman, I spent some socially-distanced time with Water Reporters, following up with them as they tracked algae blooms, marsh conditions, reported pollution, and posted about other changes they were seeing in the Bay. It’s awesome knowing that there is a whole team of people in the community helping with our Baykeeping work.

Casco Bay is heating up

Seem hotter than usual? Yes, indeed.

Our Continuous Monitoring Station has been collecting hourly data on the health of the Bay for more than four years.

Data from the station show that this summer has been the hottest one we have recorded since our “Cage of Science” has been in the water.

This graph compares water temperatures from 2016 to this month. The lavender-colored line represents the daily averages for this year.

Staff Scientist Mike Doan says “The data are concerning. This summer’s temperatures were on average the warmest we have seen at the station.”

You can find the most recent data for all the parameters we measure at our Cage of Science here.

In addition to collecting hourly data, for nearly 30 years, we have been spot-checking sites in the Bay. The temperature data from our three Sentinel Sites (see graph below for annual average, data collected May through October each year) show an upward trend as temperatures in Casco Bay have risen by 2.4° Fahrenheit [1.3° Celsius].

annual temperatures graph 2019

“Casco Bay is changing and changing quickly,” reports Executive Director Cathy Ramsdell. “That’s why we have launched the Climate Change and Casco Bay Fund, which will help us put two more Continuous Monitoring Stations in the water, one near Portland and one near Harpswell, and operate all three stations for ten years.”

The $1.5 million Climate Change and Casco Bay Fund will be used over the next decade to understand the ways in which our waters are changing, while we engage the community in assessing and adapting to climate change. Friends of Casco Bay has raised 87% of its goal for the Fund. You can read more about the Fund, our 10-year plan, and make a secure donation here.

Science: We help you see what is going on beneath the surface of the Bay

Before we started monitoring the water quality of Casco Bay, no one knew how healthy or polluted the Bay actually was. Thanks to the data we have been collecting at dozens of shoreside and offshore sites, we can state that the water temperature of Casco Bay has risen by 2.5°F, on average, since 1993.

Our long-term data set is enhanced by our Continuous Monitoring Station that has been monitoring the health of the Bay hourly, 365 days a year, since 2016. Anchored below a pier in Yarmouth, it provides the frequent, high-volume stream of data necessary to accurately track changes that may impact the oysters, clams, lobsters, and eelgrass within the Bay.

“Climate change is happening so rapidly, we needed to add to the way we collect data,” observed Research Associate Mike Doan. Since July 20, 2016, our Continuous Monitoring Station has been gathering data around the clock, all year long. Each month, we post information on 10 measures that document water quality at our monitoring site in Yarmouth, near the coastal midpoint of Casco Bay. 

Our Monitoring Station is fondly nicknamed the “Cage of Science” because its high-tech sensors are housed inside a converted lobster trap. These instruments measure temperature, salinity, oxygen, pH, carbon dioxide, and more.

These data help us gain new insights—and new questions–on the health of the Bay. Others are finding these data useful, too. Scientists use our data to inform their own research. Policy makers refer to our data to support legislative action on climate change. Classroom teachers have their students analyze our data to launch discussions on what humans can do to improve water quality. Recently, we discovered that young visitors to the Children’s Museum & Theatre of Maine measure the temperature and salinity of the Museum’s touch tank and compare their readings to our real-world data on Casco Bay.

We have posted our data online for all to see. Visit cascobay.org to see for yourself how Casco Bay is changing month by month.

The news media have recently reported on our plan to expand our array of Continuous Monitoring Stations to get a better understanding of the dynamics of Casco Bay:

Donate to Climate Change and Casco Bay Fund

September 9, 2020

We are 91% of our way to our $1.5 million goal! Help us go over the top! Friends of Casco Bay is creating a $1.5 million fund to be used over the next ten years to understand how Casco Bay is being affected by climate change. We will launch and… Read more

Keeping up with the Casco Baykeeper

September 4, 2020

For Casco Baykeeper Ivy Frignoca, the summer has been full of moments of concern and moments of magic. How was your summer? Summer means being on the Bay! Staff Scientist Mike Doan and I continued to collect our seasonal data on the health of Casco Bay by land and sea.… Read more

More eyes on Casco Bay

August 25, 2020

The meaningful observations by hundreds of Volunteer Water Reporters are making a difference for the health of Casco Bay, especially during COVID-19. Casco Bay encompasses 200 square miles of water, has more than 578 miles of shoreland from Cape Elizabeth to Phippsburg, and includes hundreds of islands. To help keep… Read more

How rainstorms affect the Bay

August 18, 2020

Today’s rain reminds us that heavy rainstorms can deliver a significant insult to the health of Casco Bay. Rainwater runoff resulting from intense storms flows into the Bay, bringing with it a host of pollutants including nitrogen, pesticides, oil, and heavy metals. If rainfall is heavy enough, the large dose… Read more

Make a difference for a decade

August 13, 2020

Casco Bay is changing and changing quickly. Rising temperatures, rising sea levels, increasing amounts of stormwater runoff, acidification — we are seeing dramatic shifts in a variety of conditions, all likely to significantly impact our economy, heritage, and way of life. We are creating a $1.5 million Climate Change and… Read more

Casco Bay is heating up

August 6, 2020

Seem hotter than usual? Yes, indeed. Our Continuous Monitoring Station has been collecting hourly data on the health of the Bay for more than four years. Data from the station show that this summer has been the hottest one we have recorded since our “Cage of Science” has been in… Read more

And how is your summer going?

Summer is going swimmingly here at Friends of Casco Bay, and we have a lot of good news to share:

  • Our priority legislative bill to create a state-level Climate Change and Ocean Acidification Council was incorporated nearly word-for-word into the Governor’s comprehensive Climate Change Council bill. An Act to Promote Clean Energy Jobs and to Establish the Maine Climate Council passed with strong bipartisan support. In recognition of her yeoman’s work on this issue, Casco Baykeeper Ivy Frignoca was invited to attend the bill signing by Governor Janet Mills on June 26th.


  • Our water quality sampling season is well underway, as we continue to add to our long-term dataset at 22 shoreside and deepwater sites around the Bay. You may see Research Associate Mike Doan and Casco Baykeeper Ivy making the rounds by land and by sea every few weeks from April through October.


  • Photo by Kevin Morris

    Since early June, Executive Director Cathy Ramsdell has been attending bi-weekly meetings of the South Portland Fertilizer Working Group to assist the City in drafting a fertilizer ordinance.


  • July 20 marks the third anniversary of the launch of our Continuous Monitoring Station in Yarmouth. Our Monitoring Station is fondly nicknamed the “Cage of Science” because its high-tech sensors are housed inside a transformed lobster trap. The instruments measure temperature, salinity, oxygen, pH, and carbon dioxide.
    Photo by Kevin Morris

    Together, they collect data once an hour, every hour, year round.  At this time of year, Mike has to scrape off a new array of marine hitchhikers whenever he hauls up the Cage of Science to download data.


  • ‘Tis the season to think about what not to put on your lawn! With five workshops behind her, Associate Director Mary Cerullo has scheduled another five BayScaping presentations for August and beyond. She is happy to talk with neighborhood groups about green yards and a blue Bay.


  • There has been such a demand by community groups to volunteer for coastal cleanups and storm drain stenciling projects that Community Engagement Coordinator Sarah Lyman and summer intern Alexis Burns have been very busy. They already have hosted seven events with 106 participants who collected an estimated 238 lbs. of trash and stenciled 238 storm drains!


  • Photo by Kevin Morris

    Our new pumpout boat, Headmaster, was launched on June 10th to pump raw sewage from the marine toilets of recreational boats. Captain Jim Splude, our congenial pumpout boat coordinator, can go about his business more efficiently now with a new boat that has more than twice the holding capacity of the old one.


  • Our Water Reporter volunteer project is expanding as we hoped and planned. Nearly 40 enthusiastic volunteers attended our Water Reporter training on June 24. Volunteers continue to sign up to keep watch over specific areas of the Bay.
    July 10 was the first anniversary of Friends of Casco Bay’s launch of the Water Reporter app. To date, 162 volunteers in this observing network have made more than 500 posts. We call that a great start!

Maine Coastal Observing Alliance releases new report

The Maine Coastal Observing Alliance (MCOA) announced the release of its new report on the region’s coastal water quality. MCOA was formed in December 2014 to coordinate a regional effort to monitor coastal waters, particularly estuaries, and detect trends such as those related to ocean acidification and nutrient loading. You can read the report here: http://www.damariscottariver.org/wp-content/uploads/2015/11/MCOA-report-Final-small-vers.-17nov15-2.pdf

Trends in Water Quality

Data collected over the past decade by Friends of Casco Bay has revealed a significant downward trend in pH in bottom water samples at our sentinel sites, as well as a marked difference in nitrogen concentrations between nearshore and offshore sites.

What’s a Sentinel Site?

Friends of Casco Bay’s staff scientists collect water quality data from the surface to the bottom year round at ten profile sites across Casco Bay. In some months, especially during the winter, bad weather prevents us from getting to all ten sites. Even so, as stalwart mariners, we have managed to visit three of the ten sites every month of the year for over 23 years. We call these sites our sentinel sites. We chose to analyze data from the bottom depths of these three sites, where conditions are less affected by wind, waves, and weather:

  • Broad Sound, our deepwater site
  • Clapboard Island, Falmouth, our “suburban” site
  • Fort Gorges, our “urban” site in Portland Harbor


pH Is an Important Factor

pH is a measure of the acidity or alkalinity of water. The pH scale is logarithmic, ranging from 0 to 14. Each whole pH value below 7 (neutral) is ten times more acidic than the next higher value. Though seawater at 8.2 is basic, the ocean’s chemistry is shifting toward the acidic side of the pH scale.

In coastal systems, many factors contribute to variations in pH. The major driver of pH change in seawater is the addition or removal of carbon dioxide. Carbon dioxide and water react to form carbonic acid. The more carbon dioxide, the more acidic the water (and the lower the pH), while the removal of carbon dioxide reduces acidity (and pH is higher). Carbon dioxide is added and removed from seawater in a number of ways, some of which are naturally occurring and some of which are exacerbated by human activity.


Dissolved Oxygen

Photo from the Times Record

Oxygen is essential to marine life. Friends of Casco Bay staff and volunteers test for dissolved oxygen, a measure of how much oxygen is available to marine life. Generally, dissolved oxygen values in Casco Bay are good. But not all areas of the Bay have healthy oxygen levels all the time. The lowest oxygen levels can be found during the early morning in the late summer at river mouths and narrow embayments. In these locations, Friends of Casco Bay has detected oxygen levels that would cause fish, lobsters, and other marine life to be stressed or killed. Low levels of dissolved oxygen in the water contributed to massive die-offs of pogies in the upper New Meadows River and Quahog Bay in the early 1990s. Long-time residents of eastern Casco Bay still remember the awful smell of rotting fish from those die-offs.


The pH of Water in Casco Bay Varies Between Night and Day

Algae can have a huge influence on pH levels in the water. On a daily basis, seaweed and phytoplankton photosynthesize, taking up carbon dioxide and releasing oxygen; this process causes pH to rise throughout the day. But at night, during respiration, algae take up oxygen and release carbon dioxide into the seawater, which lowers pH. These two processes generally result in lower pH in the morning, after a night of respiration, and steadily higher pH by late afternoon. Much of the variability of pH in Casco Bay can be explained by changes caused by photosynthesis during the day and respiration at night. Since oxygen is produced through photosynthesis and removed by respiration, we can see the dynamic in our data when we compare levels of dissolved oxygen in the water to pH: the higher the oxygen levels, the higher the pH; the lower the oxygen levels, the lower the pH. This data is available because of the efforts of our intrepid water quality volunteers, who sample both at 7 a.m. and then again at 3 p.m. on scheduled monitoring days.

The swing in pH from morning to afternoon—the diurnal difference—can be an indication of productivity. The more algae in the water, the greater the diurnal change. A healthy and productive water body will have a relatively modest change in pH from morning to afternoon, but a large swing in pH may indicate that a site is overly productive, or eutrophic. This happens when excess nitrogen over-stimulates algal growth.


The pH of Water in Casco Bay Varies Seasonally

The mean pH values in Casco Bay decline monthly between April and October. This reflects the shifting balance between algal productivity and respiration.

Seasonally, mean pH on a monthly basis drops over the course of the summer. Two dynamics are in play. As waters warm during the summer, mean pH values decline. In addition, algae blooms peak in the spring, then die and decompose through the summer into early fall. Bacteria responsible for decomposition respire and add carbon dioxide to the water and sediments. The overall effect is gradually declining pH values as we head into fall.


Our Staff Is on the Bay Year Round

Friends of Casco Bay staff scientists use our Baykeeper boat to sample our research sites monthly, all year long. By January, our vessel is usually the only boat left in the slips at Breakwater Marina, South Portland. Bundled up in work suits lined with flotation gear, Citizen Stewards Coordinator Peter Milholland and Research Associate Mike Doan shovel snow off the deck and leave early to complete the 75 nautical-mile circuit of the Bay by nightfall. Many winter mornings the air is colder than the ocean, creating a bank of sea smoke that wraps around the islands. The only other vessels encountered are commuter ferries, Coast Guard boats, and oil tankers, their bows caked with frozen sea spray. Our boat stops at each sampling station for about 20 minutes, long enough for hands to become numb. “It’s important to sample all year round in order to understand the overall health of Casco Bay,” explains Peter. By the time the crew returns to Breakwater Marina, the last rays of the setting sun momentarily blind them, a final reminder that nothing is easy on the water in winter. Yet, these stewards agree that being on Casco Bay at this time of year is magical.


Big Daily Swings in pH Can Spell Trouble

In coastal environments—like Casco Bay—there is a close link between pH and dissolved oxygen as algae add and remove oxygen from our marine waters through photosynthesis, respiration, and decay.
y = 32.1x – 151.1, R2 = 0.23*
*The trend lines of the graphs throughout this report illustrate the pattern of the data. The equation (y=) describes the trend line that best fits the data. The R2 value tells us how well the data fit around the trend line, indicating the reliability of the line.

While we expect pH to be variable, large changes in pH over the course of a day can be cause for concern. The average diurnal difference of pH in Casco Bay is about 0.1 pH units. However, some of our monitoring sites experience an average diurnal difference of as much as 0.3 units—this is a huge swing. This indicates that parts of the Bay could be eutrophic, meaning those regions will suffer from lower oxygen levels, increased carbon dioxide levels, increased acidity levels, nuisance algae outbreaks, and potential fish and shellfish die-offs.

Read the next section of the report The Double Whammy—Climate Change and Nitrogen Pollution