of Harmful Algal Blooms
A common theory is that
humans have added nutrients to the water that produce harmful algal blooms.
However, the causes are not that simple and there is no evidence in literature
to prove that reducing fertilizer use or removing septic tanks have ever reduced
the likelihood of the proliferation of an algal bloom.
Surface waters reflect
watershed condition but they are also subject to the considerable influence of
the bottom sediment, where nutrients hide. Invasive plant and animal species,
which include algae and microbes, are constantly being introduced to surface
water and they also have a dramatic impact on the condition of surface water
proliferate in warm temperatures and stagnant water but nuisance conditions are
not limited by temperature and water flow. They’re opportunistic organisms, and
extreme weather events like record high temperatures, drought, or flooding or
man-made changes to the environment may exacerbate their growth.
Increasingly, pets, livestock, wildlife, and crops are more at risk from exposure to algal blooms, but this can be avoided.
Dr. John H. Rodgers, Director of the Ecotoxicology Program at Clemson University, and a pioneer in the study of harmful algal blooms says, “Having a plan to address algal blooms is the best way to protect pets, livestock, fish, wildlife, and humans. The “do nothing” solution is not an option and avoiding the water is a poor option.”
Cyanobacteria and Health Effects
Many harmful algal blooms are produced by cyanobacteria (aka “blue-green algae”), a photosynthetic bacteria that can produce toxins.
Cyanobacteria can produce liver toxins, neurotoxins, and endotoxins. Fresh water diatoms, golden algae and some brown algae also produce toxins. Symptoms in humans and animals include muscle cramps, nausea and vomiting, diarrhea, paralysis, cardiac or respiratory difficulty, and liver failure. Death for fish, wildlife or animals can occur within hours or days.
to Pets and Livestock
Drinking from ponds showing signs of a harmful algal
bloom may prove fatal to pets, horses and livestock. Dr. Rodgers investigated an
Angus cattle kill in North Georgia. Dr.
Rodgers reports that the cattle were drinking from a farm pond and died from
microcystins that were in the water.
Unfortunately, cattle and dogs
willingly drink water affected by harmful algal blooms and even eat algae mats.
Dogs are also put at risk when exposed to cyanobacteria after licking their fur
after swimming in the water.
to Fish and Wildlife
Fish can also be susceptible to harmful algal blooms,
especially in aquaculture. Dr. Rodgers noted an aquaculture farmer in
Mississippi who lost one million fish in a day due to a harmful algal bloom. The
associated cost for the farmer was $1 million.
Cyanotoxins can even
affect marine mammals. Dr. Melissa Miller of California’s Department of Fish
and Game was lead author of a paper documenting the death of 21 southern sea
otters. Dr. Miller reported that the otters died of microcystin poisoning after
eating shellfish with concentrated levels of the toxin. A freshwater lake a
mile inland was affected by a blue-green algal bloom, and tributaries carried
cyanobacteria to Monterey Bay.
to Do in Case of Exposure
For humans and domestic animals, get away from the
water quickly. Get medical help as soon as possible.
Preventing Exposure to Algal Toxins
With early intervention and actively managing the
situation, a potential algal bloom can be
prevented altogether. Dr. Rodgers notes that “Dead algae don’t produce toxins.”
Quickly - When a problem appears, early detection
and rapid response are critical and water resource managers, including farmers
and city officials, must be observant.
A successful short-term
response uses algaecides to kill the algae. Copper-based formulations such as Cutrine ® Ultra or Algimycin® Algaecides have been proven to kill algae and cyanobacteria by
interfering with enzyme production. Non-copper formulations like Phycomycin® Algaecide are oxidizers, and quickly get to work, destroying
the cell walls. A great way to determine which product to use is The Algal Challenge Test,
which looks at the most effective algaecide to control algal concentration, while
using the least amount, a prescriptive water management approach.
Harmful Algae Blooms with a Registered Dye
Aquashade® Aquatic Plant Growth Control is EPA
registered to control cyanobacteria.
|An Algal Challenge Test done on Pawnee Reservoir in Nebraskasuccessfully predicted a treatment of Cutrine® Ultra Algaecide ontoxin-producing algae.
monitoring and treat early – Waters that are prone to
harmful algal blooms require proactive management that includes post-treatment
monitoring and follow-up treatments. A diligent lake and pond management
program will help reduce the risk of future harmful algal blooms affecting pets