Cyanobacteria in Lake Massapoag
Cyanobacteria blooms have become more frequent in New England lakes over the last several years. Lake Massapoag experienced more blooms in 2021, likely due to hot weather and three tropical storms which washed nutrients into the lake. A significant bloom in mid-July closed the entire lake for two weeks, and additional beach closures followed based on day to day sightings. Smaller suspected cyanobacteria blooms were sighted from late September until mid-October. You can see details of 2021 cyanobacteria sightings here.
If you would like to receive notifications of cyanobacteria blooms via email, please message us at [email protected], and include your name(s), preferred email address, and if you like, include a phone number and street address.
Weekly Testing
In 2022 LMAC began weekly testing of the deep hole for cyanobacteria using two methods. Microscopy was used to identify specific genuses of cyanobacteria, which is important because different genuses produce different toxins. A fluorometer was used to measure the levels of phycocyanin, a protein produced by cyanobacteria, as an indicator of the levels of cyanobacteria present.
See 2023 Cyanobacteria Test Results here.
2022 Sightings
Keep you and your pets away from these clumps, and move to a different part of the lake, beach or shoreline. They may go away and come back over the coming months.
Cyanobacteria blooms have become more frequent in New England lakes over the last several years. Lake Massapoag experienced more blooms in 2021, likely due to hot weather and three tropical storms which washed nutrients into the lake. A significant bloom in mid-July closed the entire lake for two weeks, and additional beach closures followed based on day to day sightings. Smaller suspected cyanobacteria blooms were sighted from late September until mid-October. You can see details of 2021 cyanobacteria sightings here.
If you would like to receive notifications of cyanobacteria blooms via email, please message us at [email protected], and include your name(s), preferred email address, and if you like, include a phone number and street address.
Weekly Testing
In 2022 LMAC began weekly testing of the deep hole for cyanobacteria using two methods. Microscopy was used to identify specific genuses of cyanobacteria, which is important because different genuses produce different toxins. A fluorometer was used to measure the levels of phycocyanin, a protein produced by cyanobacteria, as an indicator of the levels of cyanobacteria present.
See 2023 Cyanobacteria Test Results here.
2022 Sightings
- No significant blooms were observed June, July or August, likely due to the drought which meant little runoff of nutrients into the lake.
- On Sept 9, a cyanobacteria bloom followed a 4.3 inch rain event on Sept 5-6. The cyanobacteria appeared as bright small green bits in top few feet of water in northwest section of the lake, including the deep hole. A grab sample from the west cove (Fletcher’s cove) was 61% Dolichospermum and 39% Microcystis by microscopy and showed high levels of phycocyanin by fluorometry (1194 ug/L phycocyanin).
- On Sept 11, after two days, cyanobacteria had cleared from deeper water, but clumps of cyanobacteria persisted at some places, including the western and eastern shores.
- On Oct 16-18, cyanobacteria was sighted at Memorial Beach, along the eastern shore, and in the western (Fletcher's) cove. A sample from Memorial beach on Oct 17 showed a significant level of phycocyanin (20,280 ug/L). This bloom also cleared quickly.
Keep you and your pets away from these clumps, and move to a different part of the lake, beach or shoreline. They may go away and come back over the coming months.
Green algae, pollen and duckweed may look similar, but are not harmful
Two simple tests for cyanobacteria
Precise identification of cyanobacteria is not easy, and requires expertise and training. Find details of these simple "Float" and "Stick" tests here.
Learn more about how to identify cyanobacteria blooms here.
Cyanobacteria produce toxins
Some, but not all, cyanobacteria produce toxins which can damage liver, nerve or kidney tissue, or causes hives or a rash. Lake water testing showed that the predominant cyanobacteria in Lake Massapoag in 2022 were Microcystis and Dolichospermum.
Background on Microcystis and Dolichospermum toxins (Souce: iNaturalist)
Cyanobacteria produce toxins
Some, but not all, cyanobacteria produce toxins which can damage liver, nerve or kidney tissue, or causes hives or a rash. Lake water testing showed that the predominant cyanobacteria in Lake Massapoag in 2022 were Microcystis and Dolichospermum.
Background on Microcystis and Dolichospermum toxins (Souce: iNaturalist)
- Not all Microcystis and Dolichospermum blooms result in the release of toxins.
- Higher water temperature and light appear to be associated with increased toxin production.
- Toxins are released into the ambient environment when the cell wall degrades.
- It is not entirely known which cyanobacteria produce which toxins; the list below is preliminary.
- Microcystins are rapidly degraded by specialized, naturally occurring bacteria. If the specialized bacteria are not present, microcystins can persist in the aquatic environment for months.
- Anatoxins are rapidly degraded by sunlight & pH slightly above 7.0. At low pH, and in the absence of light, anatoxins may persist in the aquatic environment for a few weeks.
- BMAA can bioaccumulate in zooplankton and fish, and can contribute to health risks long after the toxic bloom has died back.
- Little is known about environmental degradation of cylindrospermopsin and saxitoxins, but both toxins can persist for weeks in the aquatic environment.
If you think you have been exposed to cyanotoxins, call your doctor, and read about potential lab tests and supportive treatments on the CDC Fact Sheet. There are no antidotes but actions can help.Take special care for dogs and pets near the lake, as swimming or drinking water containing cyanotoxins can be life-threatening. Dogs are more susceptible to the risks of cyanobacteria in water bodies because they may be attracted to the musty odor, and have been reported to eat shoreline deposits of toxic cyanobacteria, present either as slime and wet mats in the shallow water, or as dried crusts above the waterline.
There are do-it-yourself lake and pond cyanotoxin tests strips available online, to assess risks to dogs and other animals, but they are not lab certified.
History
Cyanobacteria are bacteria that, like plants and algae, use the energy from light to convert carbon dioxide and water into sugar and oxygen, in a process known as photosynthesis. Cyanobacteria are also known as "blue-green algae", with both of these names coming from their color. Billions of years ago, cyanobacteria, by releasing oxygen, converted earth's early oxygen-poor atmosphere into an oxygen-rich atmosphere (called the Great Oxygenation Event), creating the earth as we now know it.
Cyanobacteria and climate change
Climate change favors cyanobacteria blooms as many grow at relatively high temperatures. Increased thermal stratification of lakes enables buoyant cyanobacteria to float upwards and form dense surface blooms, giving them better access to light and a selective advantage over non-buoyant phytoplankton. Protracted droughts during summer increase water residence times and water temperature, providing ideal conditions for cyanobacteria blooms. On the other hand, extensive rain events can wash septic seepage and lawn fertilizer nutrients into the lake and cause blooms.
Dirty Dozen: Microscopic images of toxic cyanobacteria species found in New England.