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Toxins Below the Surface: What New Research Says About Algae in Lake Erie Beach Sand
A new study by researchers at Ohio State University has raised fresh concerns about the lingering effects of harmful algal blooms (HABs) along Lake Erie’s shores, this time, not in the water, but in the sand.
The research, published in June 2025 and supported by NOAA and the Ohio Sea Grant program, found that microcystin, a toxin produced by cyanobacteria during HABs, can accumulate and persist in beach sand for up to four weeks after a bloom ends.
This discovery suggests that even when the water appears safe and blooms have cleared, toxic residues may remain embedded in shoreline sediments, posing potential exposure risks to beachgoers, pets, and wildlife.
A Closer Look at the Study
The research team, led by Dr. Justin Chaffin of Ohio State’s Stone Laboratory, collected samples from several public beaches on Lake Erie. They measured microcystin levels in both surface water and adjacent shoreline sand before, during, and after algal bloom events.
The results showed that sand often retained microcystin longer than nearby water, and in some cases, the concentration of toxins in the sand was higher than in the water column. These findings align with earlier work by NOAA and other agencies that have noted the complex ways toxins can interact with shoreline environments.
One of the key concerns raised by the study is that sand is not currently included in routine public health monitoring for HABs. While state and federal agencies regularly test lake water for microcystin during bloom events, there are no standardized procedures for checking sand or sediment at beaches.
What This Means for Public Health
Microcystin is a well-documented liver toxin that can affect humans and animals through ingestion, skin contact, or inhalation of aerosolized particles. While most bloom-related health warnings focus on swimming and drinking water safety, the new findings suggest that contact with contaminated sand could also be a route of exposure, especially for children and pets who spend time digging or playing on the shore.
To date, there have been no documented cases of illness directly linked to sand-based microcystin exposure on Lake Erie, but public health researchers say the issue warrants further study.
“This doesn’t mean the beach is unsafe,” said Dr. Chaffin in an interview with local media. “But it does mean that we should consider expanding how we monitor and communicate risks after a bloom.”
A Known Problem, Now Better Understood
The idea that microcystin can bind to sediments is not new. Previous studies on lakebeds and wetlands have shown that these toxins can attach to organic matter and persist beyond the life of the visible bloom. What’s new here is the focus on beach sand, which tends to be more dynamic and more directly in contact with the public.
This study complements other recent research from Ohio State’s Aquatic Ecology Lab showing that microcystin can travel up the food web, from plankton to baitfish, and eventually to sportfish like walleye and perch. Together, these findings underscore how bloom effects can extend well beyond the open water.
Looking Ahead
There are currently no formal recommendations or signage related to toxin residues in beach sand. However, public health agencies in Ohio and other Great Lakes states are reviewing the data and may consider future guidance or expanded monitoring protocols.
For now, researchers suggest some basic precautions for beach users after major HAB events:
- Avoid letting children or pets dig or play in wet sand immediately after a bloom.
- Wash hands and exposed skin after beach visits during or following bloom season.
- Stay informed through local advisories, especially during summer months when blooms are most likely.
As Lake Erie continues to face seasonal algal blooms driven by nutrient runoff and warming temperatures, understanding how toxins behave on the shoreline may be the next important step in keeping people and ecosystems safe.