Toxic algae blooms threaten people, animals

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August 15, 2019 - 10:27 AM

Green pond scum floating on a lake is not just unsightly. As animal lovers have learned the hard way, it can be deadly.

In recent days, three pet dogs in North Carolina and another in Georgia died after swimming in water contaminated with toxic organisms.

Warm temperatures and an influx of nutrients from agricultural runoff or other sources can prompt toxic algae and bacteria to grow out of control. The result is a phenomenon called a toxic algae bloom.

As the planet warms, these blooms are becoming more frequent — leading to a greater chance for human and animal exposure.

Here’s what you need to know to protect yourself and your pets from toxic algae blooms.

WHAT ARE ALGAE?

Algae are plant-like organisms that grow in water or other damp environments. They can be as small as a single cell or as large as a kelp forest. For the most part, they get their energy through photosynthesis. However, they lack roots, leaves and other characteristic components of plants.

The microorganisms known as blue-green algae aren’t actually algae at all. They are cyanobacteria, bacterial cells that get their energy from photosynthesis.

Toxic blooms in freshwater lakes and streams are usually caused by cyanobacteria, while blooms that occur in the ocean are typically the result of algae.

WHAT IS AN ALGAE BLOOM?

A bloom occurs when algae or cyanobacteria suddenly grow to huge numbers. In 2011, for instance, a toxic algae bloom in Lake Erie grew so large over the course of four days that it could be seen from space. This growth is typically fueled by warm temperatures, still water and nutrients such as nitrogen and phosphorous.

Algae blooms can range from completely innocuous to incredibly toxic, said David Caron, a microbial ecologist at USC. They can turn the water different colors, from bright reds and greens to shades of brownish-yellow.

WHAT MAKES THEM HARMFUL?

Some species of algae release toxins into their aquatic environment. During a bloom, the concentration of toxins in the water can reach levels that are dangerous for both humans and animals.

The type of toxin released depends on the species causing the bloom. Some of the most common ones affect the liver or the nervous system, said Donald Anderson, director of the U.S. National Office for Harmful Algal Blooms and a senior scientist at the Woods Hole Oceanographic Institute.

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