Algal blooms brought on by climate change and nutrient runoff a danger to fishing, coastal communities

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By Domenic Purdy, Spencer Hayes and Madison Ledyard-King

An active algal bloom consumes Lake Erie where summer blooms have impacted fishing and recreational activities. “You have to adapt with time,” said longtime fisherman David Koch, founder of Sandusky’s Whites Landings Fisheries in Ohio.
Photo credit: National Oceanic and Atmospheric Administration

Summer is here. That means mouth-watering barbecues, sunscreen and fun on the water. 

But thanks in part to rising temperatures due to climate change, vacationers may run into unwanted guests as summers become warmer: algal blooms. 

Waterways separated by thousands of miles are experiencing a dangerous buildup of algae, not just ruining family fun, but threatening people’s livelihoods. 

For blue collar workers like Acy Cooper Jr., president of the Louisiana Shrimp Association and a third-generation shrimper in Buras, Louisiana, algae has significantly impacted his livelihood. Cooper says algal blooms have drastically affected every stage of his business, starting with the shrimp themselves.  

“Nothing lives in algal blooms,” Cooper said. “That means no oxygen, no life. It’s a really big issue for us.” 

Five states away, in Ohio, the fishermen of Lake Erie are adapting to the new reality presented by algal blooms differently than Louisiana’s shrimpers are. For Dean Koch, founder of and semi-retired fishermen for Whites Landings Fisheries Inc., harmful algae has become a part of his day-to-day life as a fisherman in Sandusky.  

“You have to adapt with time,” Koch said. “We’ve had to change somewhat of what we do in treating our nets.” 

By doing something as simple as coating nets with anti-fouling paint that hinders the growth of aquatic organisms, Koch significantly reduces algae buildup. It’s little changes like this, he feels, that make adapting to algal blooms all the easier. 

While Koch and his contemporaries in the fishing industry adapt to blooms, scientists across the country are studying what makes this algae tick.  

Algae—referred to as cyanobacteria by ecologists—is only dangerous when it accumulates into harmful blooms that shrimpers and fishermen across the country encounter. Algae is not inherently a danger to the planet’s ecological health. In fact, these microscopic plants are the base of a balanced aquatic ecosystem. 

“They are not harmful by any means in normal cases,” said Sibel Bargu Ates, associate dean of Louisiana State University’s College of the Coast & Environment. “When the balance is destroyed, then you start getting these negative impacts.” 

Bargu Ates said harmful algal blooms like the ones affecting Lake Erie and the Louisiana coast are partially a result of the imbalance brought on by rising global temperatures. This overaccumulation of algae in bodies of fresh and coastal water present across all 50 states is also exacerbated by an excess of nutrients that the system cannot handle.  

The process of nutrification that brings excess nutrients into aquatic systems is at least partially caused by mankind. According to the Natural Resources Defense Council, an estimated 10 trillion gallons of untreated, nutrient-rich storm runoff makes its way into waterways each year. 

Bargu Ates explained that agricultural runoff, like pesticides and herbicides, also carries nutrients that fuel harmful algal blooms. In Louisiana, natural and manmade diversions like levees along the Mississippi River send harmful amounts of nutrients into estuaries. 

“If you link them to an excess nutrient entry into the system, then you can look at all these negative effects,” Bargu Ates said. “Sometimes they reduce the oxygen and cause hypoxia [ a condition that kills fish populations] or they change the color of the water and that affects the economy.” 

Elizabeth Wick, the former manager of the Ohio EPA Division of Surface Water, has seen the firsthand effects of nutrient runoff in the production of harmful algal blooms since her childhood visits to Lake Erie. 

“When I was a kid and we drove by Cleveland, you would just die from the smell. It was horrible,” Wick said. 

For many Americans, summer means trips to the shore, including Ohio’s Headlands Beach State Park. But thanks in part to rising temperatures due to climate change, vacationers may run into an unwanted guest — algal blooms.
Photo: Spencer Hayes, Climate 360

But in the 1970s, Wick said these issues more or less disappeared. In the last decade, however, Lake Erie’s natural beauty is being actively threatened once again. 

Utilizing a federal grant, Wick’s team at the EPA sampled for nutrients that stimulated recent algal bloom growth and made startling discoveries about the levels of specific nutrients. 

“[The team] sampled for nutrients, so they did the phosphorus and chlorophyll A, which are the leading causes of the algal blooms,” Wick said. “They would definitely see the trends, and they would predict that yeah, the bloom is coming because of the levels increasing.” 

Wick sees monitoring and regulating the usage of nutrients like phosphorus in farming as a potential remedy to harmful blooms across the nation. She said that the first step in restoring a balanced ecosystem is to incentivize farmers to reuse runoff water from their fields in order to reduce the amount that reaches waterways like Erie. 

“I think we can reduce it. We may never get rid of it totally,” Wick said. “So, if we can reduce runoff, we can try to take away food source [of the blooms], then we might be able to reduce it. I think we will always have algae; it’s just trying to stop the toxic algal blooms.” 

Along with agricultural runoff, experts like Wick and Bargu Ates also attribute the growth of blooms like the ones found in Lake Erie and along the Louisiana coast to rising global temperatures. Blooms like the ones researched by Wick and her team at the Ohio EPA thrive in warmer waters, only exacerbated by the presence of excess nutrients. 

“Prevention and mitigation are the two most important steps,” Bargu Ates said. “The future is going to be all about predicting these blooms and preventing the things that cause them. We have such a powerful influence over these natural changes. We are messing up the Earth quite a bit, and it’s time to take responsibility.” 

A sign on the Ohio shore of Lake Erie warns beachgoers of the danger of algae toxins. Annual summer blooms have been reported throughout the United States, including Maryland’s Chesapeake Bay and Louisiana’s Lake Pontchartrain.
Photo: Spencer Hayes, Climate 360

To experts like Wick and Bargu Ates, the way to restore the balance of algae in aquatic ecosystems is a proactive response. According to Bargu Ates, mankind needs to acknowledge our role in these blooms if we’re going to win the battle against harmful algae. 

Climate experts find education to be the key to combating the development of harmful algal blooms. Bargu Ates and Wick envision a world where shrimpers like Cooper and fishermen like Koch are able to assist scientists in taking action against algal blooms.  

“We just need to communicate with them,” Bargu Ates said. “With the right education, they can be helpers to scientists to identify these things, but at the same time, that has to be a nutrient management issue that needs to be taken care of.” 

For Koch, who has been working as a commercial fisherman since the 1960s, learning about algal blooms is important for business.  

“I think climate change has had a lot to do with our weather patterns,” Koch said. “And I think studying those things are important as the climate changes.” 

A satellite image (zoomed in on Lake Erie’s western basin, left) and accompanying illustration (right) display early season blooms in Lake Erie in May 2021. Whether the blooms will continue to grow will depend on summer rainfall totals.
Photo credit: National Oceanic and Atmospheric Administration

Wick’s work at the EPA was primarily concerned with educating and involving fishermen in the process of countering the effects of harmful algal blooms at their source.  

“We had a couple [commercial fishing captains] that were trained, and so when they were out on Lake Erie, they could pull the samples and bring them in,” Wick explained. “They say that the fish definitely leave the algal bloom areas. So, fish know if there is a low oxygen level to leave.” 

Wick put it plainly: “As you get these bigger blooms, you’re going to get less fish.” 

Less fish in Louisiana can be disastrous for local communities. In her studies on the effects of the blooms, Bargu Ates found that water discoloration paired with decreasing fish populations have a severe effect on local tourism and culinary industries.  

While the harmful blooms that Cooper and Koch encounter on American waterways have the capacity to ruin lives, algae’s benefits should also be recognized. Algae produces about 50% of the oxygen we breathe, Bargu Ates said. 

“These are amazingly important organisms to us, but if we change the balance, then they can also cause some harm,” Bargu Ates explained. “We have to bring back balanced conditions, so they can be happy. Fish can be happy, and we can be happy too.” 



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May 2024


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