Cyanobacteria Alerts From Multiple Sources Cause Confusion

BREWSTER – Cyanobacteria blooms are not new, but they are becoming more prevalent. 

The common phrase “survival of the fittest” is a perfect way to describe cyanobacteria organisms, said Dr. Kim Crocker Pearson, chair of the town’s natural resources advisory commission. 

Their origin dates back to ancient times, and throughout the centuries they have developed special adaptations to survive. According to Pearson, the rise of these blooms is related to changes in the environment, including humans. 

“Not only is it complicated,” said Pearson, “it is going to become ever more complicated as we learn more about them.” 

As residents receive an increased number of alerts about the cyanobacteria blooms in local Brewster ponds, Pearson said it’s hard to know which ones are toxic. On Aug. 5, residents were alerted to a cyanobacteria advisory for Seymour Pond. The advisory will now remain in place for a minimum of two weeks as monitoring continues. 

Over the last few years, the Association to Preserve Cape Cod (APCC) has changed its monitoring approach and risk tiers several times. The agency is currently monitoring and releasing alerts based on its own guidelines. The town releases advisories based on feedback from the health department.

Currently, the APCC is using cyanobacteria pigment as a rapid indicator for potential toxic blooms. Pearson said while this approach can help provide early alerts, there are two major limitations. 

There are many different types of cyanobacteria that produce different amounts of toxin at the same cyanobacteria pigment concentration. This means it’s hard to gauge the level of toxins in the blooms based on pigment alone. 

Additionally, the same types of cyanobacteria may produce different amounts of toxins in different ponds. 

With all that said, the variability of the organisms leads to uncertainties in the monitoring approach. 

In a comparison of the APCC’s risk tiers between 2020 and 2025, it is clear that precision has been lost. In 2020, the guidelines look at two different genus of cyanobacteria with very specific threshold levels of micrograms per liter. By 2025, the guidelines have become less precise, with only one genus being tested.

Pearson said the “2025 thresholds could therefore increase the number of Brewster ponds elevated to APCC’s ‘potential of concern’ tier without providing a concomitant public health benefit.”

The board of health said there is a difference between closing ponds and beaches and issuing advisories. 

On Aug. 6, residents were alerted to a temporary closure of Paines Creek Beach after routine testing showed high levels of fecal bacteria. Pearson said the closure of the beach in this instance was warranted for health reasons, but the town does not close its ponds for cyanobacteria notices. Instead, the town offers a recommendation to avoid recreational activities including swimming or other direct contact with the water. 

In a phone call, new health director Daniel Syriala said no cause has been found for the fecal coliform high levels at Paines Creek Beach. 

“It’s one of those random things,” he said. “Every so often you’ll have an exceedance and it could be as simple as someone emptying their waste tank on a boat driving by.” He said there would be no further investigation. 

Select Board Chair Mary Chaffee confirmed that the APCC doesn’t have a state-mandated role in the cyanobacteria monitoring of town ponds. Brewster currently follows the state’s department of health regulations.

“It’s confusing at times to have organizations that are not necessarily [providing] conflicting reports, but they are reports that don’t necessarily sound the same,” said Pete Dahl, select board member. “I find that problematic.” 

If residents come across what they believe are suspicious blooms, Syriala said they should call the health department and provide an exact location so staff can investigate.

After discussing what cost-effective solutions could help with spreading knowledge about cyanobacteria and the potential toxins, Pearson pivoted the conversation. 

“We’re talking a lot about cyanobacteria tonight,” she said. “But a reminder that about 420 kids per year drown in ponds and lakes. Oftentimes that’s because there isn’t accessible lifesaving equipment. Zero kids die from cyanobacteria in the United States per year. That’s a big difference in those numbers, so we might want to think about putting our money toward anti-drowning protocols.”