Researchers find fish-killing algae thrive in light conditions associated with climate change

A new University of Delaware study shows that changing light conditions associated with climate change will significantly increase the growth and impact of harmful algal blooms, creating powerful and persistent disruptions in the food web.

The causes of harmful algal blooms may vary, but typically farm runoff, wastewater from failing septic systems, or effluent from inadequate wastewater treatment plants finds its way into surface water bodies. These sources carry elevated levels of nutrients, especially nitrogen and phosphorous, which cause explosive growth of algae in surface water.

Decaying algae frequently demand so much oxygen from the water that marine life can no longer survive, a condition known as eutrophication. Blooms of toxic varieties of algae also threaten animals and humans.

Fish Killer Algae Adapt to Changing Light

The University of Delaware study focused on the microscopic Karlodinium veneficum algae found in Delaware bays. The algae, which are known as fish killers, cause periodic Chesapeake Bay dead zones that harm the ecosystem.

Fish killer algae are mixotrophic, which means they’re adaptable to changing conditions, sometimes taking nourishment from sunlight and at other times consuming other algae and bacteria. The single-celled organisms can move independently with flagella and even stun their microscopic prey with toxins.

Researchers discovered another adaptive feature of the species: It altered its growth strategy when light and temperature conditions changed. In low-light conditions, the organisms gorged themselves on carbon and nitrogen, but the populations did not increase. In conditions of greater light, the algae consumed less carbon and nitrogen, but the populations increased.

This species of algae may, therefore, become less nutritious in a warmer future. Creatures that depend on it for food and control its populations may suffer, with consequences for the aquatic environment and the wider food web.

In the laboratory, the algae also quickly adapted to higher temperatures than they had tolerated previously, so the researchers do not expect higher temperatures associated with climate change to deter the species.

Algae’s Effects on Food Web Controlled by Decentralized Wastewater Treatment

Dr. Kathryn Coyne, associate professor at the University of Delaware College of Earth Ocean and the Environment and lead author of the study, explained the effects of changing light conditions and warming on algal blooms:

Especially for blooms that occur near shore, these are likely to get worse and extend not just temporally as the growing season is longer, but also geographically, where the temperature or light regime was not favorable for growth before.

The researchers also expect the number of blooms to grow, according to the article on the ScienceDaily website.

A number of strategies have proven effective against overgrowth of algae. In agriculture, grass strips serving as buffer zones around agricultural fields can naturally remove nutrients from runoff.

Newer decentralized wastewater treatment units such as Fluence’s Aspiral™ can be deployed at the small or medium scale to treat sources in rural growing zones, small communities, or industrial sites.

In lakes, lagoons, and ponds, aerators like the Fluence TORNADO® can prevent algae blooms. Fluence’s AuraAER^® solar floating fountain can control algae in less-intensive applications while adding to aesthetic quality.

Regulators increasingly are addressing nutrient pollution throughout watersheds in response to harmful algal blooms. For help navigating the new regulatory landscape, contact the wastewater treatment experts at Fluence. It has never been easier to bring the extremely high nutrient removal rates of our membrane aerated biofilm reactor (MABR) technology and the American-made quality of our aerators and fountains to your community, resort, agricultural zone, or industrial site.