Although the warm summer season is just getting underway, in the past week a number of Cape Cod freshwater ponds are experiencing significant impacts from cyanobacteria blooms, often, but not always, seen as a thick scum of growth also known as blue-green algae.
Many of the cyanobacteria blooms now occurring were identified through a monitoring program initiated by the Association to Preserve Cape Cod. Working with the Brewster Ponds Coalition, Friends of Chatham Waterways, Indian Ponds Association, several towns, and with the support of researchers at the University of New Hampshire Center for Freshwater Biology, APCC and its partners are monitoring ponds across the Cape to document the occurrence of cyanobacteria and report results.
APCC is currently monitoring 22 ponds, with the possibility of expanding to other locations later in the summer season. The town of Barnstable is monitoring about 20 ponds additional ponds.
As of June 21, recreational use advisories to avoid all contact with water were issued for Santuit Pond in Mashpee, Bearse Pond in Barnstable and Upper Mill Pond in Brewster. These advisories were issued by the towns with the support of the Massachusetts Department of Public Health.
The town of Barnstable has issued advisories for Lake Wequaquet and Hinckley Pond, recommending that pet owners avoid letting their pets come in contact with the water.
Cliff Pond at Nickerson State Park in Brewster, Lovells Pond in Barnstable and Scargo Lake in Dennis are ponds of concern and are being closely monitored.
Other ponds on the Cape may be impacted but are not being monitored. Cape Cod has approximately one thousand freshwater ponds.
Cyanobacteria are naturally occurring, and their presence in Cape ponds in normal amounts is not problematic. However, excessive nutrients from septic systems and fertilizers, combined with warming water temperatures attributed to climate change, creates ideal conditions for cyanobacteria to multiply rapidly and dominate a pond system in what are known as harmful cyanobacteria blooms, or HCBs.
HCBs are an increasingly common occurrence in freshwater ponds across the Cape. They pose a serious environmental and public health concern, having the potential to produce dangerously potent cyanotoxins that are a health threat to humans, pets and wild animals.
Most cyanotoxins fall within the categories of hepatotoxins or neurotoxins. In worse-case scenarios, exposure can result in damage to the liver and nervous system in humans. Exposure to cyanotoxins can occur through direct skin contact from swimming in ponds or by ingesting pond water. Breathing in cyanotoxins can also be a concern, since certain cyanotoxins have been measured in the air downwind of lakes experiencing cyanobacteria blooms.
Several dog fatalities on the Cape in past years have been linked to exposure to cyanotoxins in local ponds.
HCBs can also threaten freshwater ecosystems by clouding water and reducing dissolved oxygen to dangerous levels for fish and other aquatic organisms.
Compared to recent seasons, the presence of cyanobacteria and HCBs in ponds across the Cape in 2019 has so far been significantly greater, according to APCC’s monitoring.
APCC is maintaining an up-to-date online interactive map and informational webpage at www.apcc.org/cyano to share monitoring results with the public throughout the summer season. Active advisories for specific ponds are posted on the site. Town health or natural resource departments can also be contacted to ask about active advisory notices.
While some Cape towns are watching for HCBs at their public swimming beaches, most have very limited capacity to adequately monitor ponds and manage the problem.
“APCC’s monitoring program supplements and enhances limited municipal efforts and provides a significant layer of additional protection to the public,” said Andrew Gottlieb, APCC’s executive director.
“The quality of our freshwater ponds has long been taken for granted,” said Gottlieb. “Lakes and ponds are as sensitive to nutrient enrichment as our bays are and we are seeing the impact of overfertilization now. With climate change causing water temperatures to warm and nutrients from lawn fertilization and septic waste creating the conditions algae need to thrive, we should expect this problem to continue to worsen if we don’t commit to solving this problem.”
“As the Cape’s major environmental watchdog, APCC established the monitoring program to help raise public awareness, inform towns of potentially dangerous conditions in their ponds so they can post advisory notices when needed, and help residents and visitors make informed decisions about their use of local ponds,” explained Gottlieb. “We also hope a greater understanding of the issue underscores the need to treat pond and lake health as the Cape’s next major water quality challenge.”
To learn more about APCC’s cyanobacteria program, visit www.apcc.org/cyano or contact APCC at 508-619-3185.