Jamaica Pond closed for harmful cyanobacteria known to kill dogs, animals

BOSTON — Heat, rain and subsequent run-off -- those are the usual culprits when bodies of water blossom with algae.

It’s unclear exactly what caused Jamaica Pond to turn a murky shade of olive this weekend -- but the reason for the discoloration is known: an overgrowth of cyanobacteria, otherwise known as blue-green algae.

Boston health officials closed the pond to people and pets as a result. Due to the blue-green algae, park visitors are not allowed to swim, fish, boat, or engage in other activities in or on the water.

Naturally present in small amounts in lakes, ponds and rivers, cyanobacteria grow into harmful “blooms” when a nutrient source enters water warmed over the summer months. Nitrogen and phosphorus from fertilizer run-off can trigger a bloom -- as can septic leakage.

When cyanobacteria cells die, they release potent cyanotoxins which have a variety of effects on animal and human bodies. Dogs are most commonly affected, as they tend to play in and drink from bodies of water.

“Our dog Jackie, she loves coming to the pond,” said dog owner Marina Jones. “She loves to cool off whenever we come down here.”

Fortunately, Marina and her husband George had seen the warning signs posted by Boston city health officials and they were steering clear of the pond -- even altering their route to keep Jackie’s mind off the water.

“It’s a fight, it’s a fight,” said George Jones. “She wants to go in and, you know, she can’t.”

Dogs exposed to cyanotoxins can experience a range of severe effects -- from seizures to gastrointestinal problems -- all the way to liver and brain damage and even death.

While CDC does not include death as a possibility for humans exposed to cyanotoxins, it does list liver damage, gastrointestinal and neurological effects -- as well as irritation to the skin, respiratory tract and eyes.

This is a developing story. Check back for updates as more information becomes available.

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