New News on the Blue-Green Algae

As the summer winds on, the blue-green algae bloom in Georgica Pond has expanded and intensified.   Remember, blue-green algae are of serious concern as they synthesize toxins that can sicken humans and can be lethal to pets and other animals.  Here is the latest information regarding the blue-green algae bloom in Georgica Pond.

  1. The small bloom that originated in the southern end of the Pond only on August 12th has now spread into Georgica Cove and into the north end of the Pond as well.
  2. The biomass levels presently in the Pond (>400 micrograms of blue-green algal pigment per liter) are the highest levels we have recorded since we began monitoring in 2013.
  3. In good news, this bloom is currently displaying low levels of toxicity. We have analyzed samples for the neurotoxin, anatoxin-a, and it was not present in the Pond.  We have analyzed samples for the gastrointestinal toxin, microcystin, and the levels were 1 micrograms per liter.  This is at the World Health Organization’s limit for safe drinking water, so no one and no animal should be drinking from the Pond.  However, the World Health Organization considers 2 micrograms per liter a low recreational risk and hence the current levels are NOT a recreational risk according to this standard.
  4. As predicted earlier in the year, blue-green algae did not start to bloom in Georgica Pond until the salinity of the Pond dropped to a low level as they cannot tolerate high salt levels. This year’s trigger point seemed to be about 13 grams of salt per kilogram of water. To prove this point further, my lab recently performed a bottle experiment of adding ocean water to Pond water, raising the salinity to 21 grams per kilogram and found it reduced blue green algae levels by more than 50% in 48 hours.  Hence, opening the cut would eliminate the blue-green algae in two ways: physically by flushing and physiologically by killing them off.