Harmful Algae Blooms
by Dan Grigas, Natural Resources
To say that algae play a role in life under the water is an understatement. Algae are paramount importance to aquatic life. They provide the basis of the food web and oxygenate water and the atmosphere. Without algae, our waterways would be barren wastelands providing little in the way of biological diversity.
There are many types of algae, but algae in freshwater ecosystems fall into three main groups: diatoms, green algae and blue-green algae. Diatoms are sensitive to environmental change, so their presence lets ecologists know an ecosystem is fairly healthy (even though to the naked eye masses of diatoms can look like brown slime). Green algae are brighter; in water they can look like lime-colored strands of hair. Both diatoms and green algae are common, but as summer progresses and the weather warms, in nutrient-rich waters exposed to long stretches of hot and sunny weather, single-cell blue-green algae can also develop.
Blue-green algae, or “cyanobacteria,” form large colonies, or “blooms” that can look like dense mats, foam or floating paint, although affected waters can also look normal on the surface. Some people call these blooms “pond scum.” Blooms can be beneficial for the ecosystem, but they can also be problematic under the right conditions. When certain toxin-producing cyanobacteria dominate a bloom and start to release those toxins as the algae cells begin to die, the bloom becomes a “harmful” algae bloom, or HAB.
In animals (which of course includes people), contact with HABs can cause a range of adverse health conditions from skin irritations to liver, gastrointestinal or nervous system issues, mostly through two primary routes of exposure. The first route is direct contact with contaminated water. Swimming isn’t allowed in DuPage forest preserves, but people can still come in contact with blooms while fishing or boating, the biggest risk coming from handling wet equipment. The second route, and most prevalent for domestic pets, is ingestion. (A third but less prevalent route occurs when people inhale airborne toxins, but that normally occurs during high-speed water sports, near decorative fountains, or during extreme wave conditions, which cause fine water droplets to drift through the air, all unlikely in DuPage forest preserves.)