Satellite picture of a Phytoplankton bloom along the coast of Iceland.

When Algae Turns into “Too Much of a Good Thing”

By Whitney Beck, Sustainability Leadership Fellow and PhD Candidate in the Department of Biology and Graduate Degree Program in Ecology

I’ve heard that you can thank algae for one out of every two breaths you take, which makes sense. Algae generate at least 40% of earth’s oxygen through photosynthesis, the conversion of carbon dioxide and water into oxygen and sugars. Algae is so abundant that you can sometimes see it from space, and all of this algae produces a wealth of benefits and costs to human society and the environment.

Satellite picture of a Phytoplankton bloom along the coast of Iceland.
Phytoplankton bloom along the coast of Iceland. Source: Wikimedia, Credit: NASA’s Earth Observatory.

Algae produce numerous economic and environmental benefits for humans and other species. First of all, algae can “breathe in” and store some of the carbon dioxide humans have been pumping into the atmosphere. You may not realize how much algae you consume on a daily basis, but a wide variety of products from toothpaste to ice cream to dietary supplements contain algae. Algal not only gives food a denser consistency, but also has a number of reported health benefits. Additionally, many companies and agencies are funding research on algal biofuels, which may be a potential replacement for fossil fuels like oil in the future. Ecologically, algae serve as the basis for many aquatic food webs, fueling the growth of fish, insects, snails, and other organisms. This produces substantial benefits for humans recreating in aquatic systems and profiting from aquatic products.

If algae have all of these fantastic benefits, why are we worried about the blooms in Florida? You may have read about the cyanobacteria (or blue-green algae) plaguing Lake Okeechobee or the red tide covering Florida’s coastline. In large amounts, algae can harm humans and ecosystems by producing toxins, lowering water oxygen content when it dies and decomposes, and blocking sunlight from the water column. Like in so many other areas of life, too much of a good thing produces negative consequences!

Woman in canoe paddling through large blooms of algae.
Woman paddling through large blooms of algae. Source: Wikimedia, Credit: U. S. Environmental Protection Agency, Author: John Moran.

To understand the cause of the problem in Florida, we need to review some basics of algal ecology. Algae are like plants, relying on sunlight and nutrients like nitrogen and phosphorus to grow. Additionally, algae grow faster with warmer temperatures. In healthy ecosystems, algal abundances can be controlled by insects and fish that consume algae. However, human activities have increased the nutrients in waterways, which leads to excess algal growth that remains unchecked by animal consumption (especially since some of the algae are toxic). Excess nutrients are the result of agricultural and garden fertilizers running off into waterways; wastewater treatment plants and leaky septic tanks releasing nutrient-rich waste; urban construction producing erosion of phosphorus-rich soils; and factories, cars, and manure piles emitting nitrogen into the atmosphere, which then enters waterbodies via rainfall.

Some watersheds across the country are required to reduce nutrients under the law, but others have yet to be strictly regulated. Many policies and programs can be implemented to reduce nutrients in the nation’s waterways. First, nutrient management plans and agricultural best management practices can reduce the amount of nutrients entering aquatic systems. For instance, planting trees next to streams can ensure that nutrients are taken up by plants before reaching the water, and tree roots also stabilize the soil to prevent erosion. Construction projects in urban areas can also use best management practices to prevent erosion of nutrient-rich soils into the waterways, for instance by building fences that trap eroded soils on-site. Some wastewater treatment plants are being upgraded to include nutrient removal technologies, but funding for infrastructure upgrades remains a challenge in many regions of the country. Successful pilot programs in Canada have shown that nutrients can be recovered from wastewater and sold as fertilizer to help mitigate infrastructure upgrade costs.

Streamside trees in agricultural fields
fences that trap soils at construction sites

Streamside trees in agricultural fields (left) and fences that trap soils at construction sites (right) are two examples of best management practices that can help prevent nutrient pollution. Source: Wikimedia, Credit: USDA NRCS (Left) Source: Wikimedia, Credit: USFWS Midwest (Right)

Great, our state and local governments have a lot of options if the political will (or regulatory requirement) exists to reduce nutrients and prevent algal blooms. And the public often does support these actions—for instance, a survey found that 95% of Virginia residents supported plans to clean up the Chesapeake Bay, and Florida residents have overwhelmingly called for increased efforts to reduce algal blooms. But what can you do as an individual? First, if you have a garden or lawn, I would recommend getting your soil nutrients tested so you don’t apply more fertilizers than necessary. Second, check out local watershed groups seeking to protect local rivers, streams, lakes, and coasts. Consider volunteering (either outdoors or in the office) or donating to these organizations. Finally, consider supporting local and state policies on water quality monitoring and pollution reduction.

To summarize, we depend heavily on algae for environmental and economic services. As with most areas of life, too much of a good thing can be detrimental—high nutrient levels and temperatures lead to harmful levels of algal growth in aquatic ecosystems. We must pursue individual actions and government policies to protect and restore vulnerable ecosystems and economies in places like Florida and beyond.

Share this post