Top Five: The Worst Toxic Algal Blooms of 2022 and What They Tell Us About Climate Change

December 14, 2022

Eyal Harel

CEO, BlueGreen Water Technologies 

Toxic algal blooms are a growing global menace, choking the life out of water bodies from one continent to the next. Caused by a rapid eruption in microorganisms such as cyanobacteria, dinoflagellates, and Heterosigma akashiwo, algal blooms destroy aquatic ecosystems and endanger the health of people, pets, and wildlife. The ripple effects can be crippling to societies, rendering drinking water supplies unsafe, harming livelihoods, and damaging local economies. As if on cue, these poisonous invaders tend to return to the same water bodies year after year. 

The continued explosion of toxins in our water bodies has led to a staggering increase in aquatic dead zones. By one estimate, the earth now holds more than 95 thousand square miles of hypoxic aquatic zones - that’s about the size of the United Kingdom! And as the world stands by, climate change is only exacerbating this threat.

As the year comes to a close, let us look back at the top five worst toxic algal blooms of 2022 and vow to do better in the years to come. 

San Francisco Bay, California

The 2022 summer spectacle in California’s San Francisco Bay area looked like a scene out of a horror movie: tens of thousands of dead fish poisoned by red tide fouled the shoreline. The rotting carcasses of sharks, sturgeon, rays, striped bass, and countless other fish and crabs were piling up by Labor Day weekend.  

First detected in the Alameda Estuary in July, the rapid explosion of a microorganism identified as Heterosigma akashiwo fueled the worst red tide outbreak in the Bay’s recorded history. A triple-digit heatwave and extreme drought only exacerbated the problem.

Though toxic algal blooms are by no means an unusual occurrence in California, the scale and severity of this year’s outbreak exceeded even the worst prediction models. The scenes from what may be called California’s Summer of Aquatic Carnage were grotesque and sad. Without effective preventive measures, there will be a sequel. 

Dianchi Lake, Yunnan, China

Covering 115 square miles, Dianchi is the largest lake in Yunnan Province. The so-called “mother lake” has deep cultural meaning for residents, as described in a popular local nursery rhyme:

"Dianchi Lake stretches far into the sky with clear water sparkling in boundless width. Row your boat, dance with fish, and happily return home after sunset." 

But since the late 20th century, Dianchi has been one of China’s most polluted lakes. As in other years, the summer of 2022 brought a thick layer of blue-green algae to the water’s surface and a strong stench.

At times the toxicity on Dianchi has been so severe the lake has been deemed too dangerous for human contact. Over the years, outbreaks have led to loss of habitat and the extinction of endemic fish species. Higher temperatures, less rainfall, and the flow of industrial and nutrient runoff into the lake are blamed for the persistent outbreaks. 

With billions of dollars spent on mitigation efforts, the hope is that one day locals will see the “clear water sparkling” referenced in the nursery rhyme return to their mother lake. 

Clear Lake, California

There’s no way to sugarcoat it:  Summer after summer, California’s Clear Lake turns into a festering cesspool of green gunk. The summer of 2022 was no different. Noxious blooms of toxic algae forced residents indoors to escape the stench and avoid the headaches and respiratory problems caused simply by breathing in the vicinity of the infected water body next door. 

California’s second largest lake has been plagued by toxic blooms for decades. This summer marked another year that residents were warned not to drink water from private systems that draw from the lake.

Drought, runoff, and rising temperatures that linger longer year after year have created a perfect storm of conditions to allow toxic algae to thrive in Clear Lake.

Elands Bay, South Africa

In the fishing village of Elands Bay, South Africa, an outbreak of harmful algae forced a mass stranding of west coast rock lobsters in February. About 500 tons washed ashore, covering a five kilometer stretch of coastline. 

Unfortunately, this is a recurring problem for Elands and surrounding bays. Harmful algal blooms have increased sixfold along South Africa’s west coast over the past few decades. In the 1990’s alone, scientists report a 24-fold increase in estimated tonnage of stranded rock lobster compared with the previous 30 years. 

The increase is thought to be driven, in part, by the Benguela Current, which flows north from the southern tip of Africa carrying an abundance of nutrients. The resulting blooms of phytoplankton create low oxygen conditions that can lead to mass strandings.

Lake Erie, Ohio, U.S.

On the western side of Lake Erie, a familiar, dreaded, soupy green began creeping across the water’s surface in mid July, sending a sick, decaying smell wafting across the water. Lake Erie’s summer blooms are among the worst accumulations of toxic algae in the U.S. The epic bloom of 2014 contaminated the city of Toledo’s drinking water, forcing a system shutdown for days and sending residents scrambling for bottled water. 

Sadly, no one is surprised by the annual eruptions; the only question is how severe it will be.  NOAA’s severity index scored the 2022 bloom at 6.8, moderately severe. Measuring 416 square miles, the bloom was not as large as the outbreak in 2021, but it was more concentrated and therefore, considered more severe than last year’s edition.

What We Can Learn From 2022

2022 once again confirmed that toxic algal blooms are growing in severity and frequency around the world. The fact remains: global leaders, environmental regulators, states, municipalities, and regional water districts must do more to prevent and remediate these outbreaks. Despite overwhelming science, despite the outcry from experts and advocacy groups and citizens, this toxic plague persists. We must break the pattern. 

At the United Nations’s recent conference on climate change, COP27, Water and Climate Coalition Leaders called on world leaders to better manage and integrate water and climate action. As the planet continues to warm, sea level rise, flooding, droughts, heat waves, and water pollution will only worsen.

Sounding the alarm on the global stage helps, but it must be backed up with action.

Water nourishes our planet. Clean water supports life and protects ecosystems. It ensures the diversity of species. It is our most precious natural resource and we must protect it.

Mountains above a clear lake

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