Plastic Pollution Linked to Toxic Algae Blooms, Study Finds

UC San Diego researchers discover that petroleum-based plastics can disrupt aquatic ecosystems and contribute to harmful algal blooms.

Jan. 30, 2026 at 1:31am

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A new study by researchers at the University of California San Diego has found that plastic pollution, particularly from petroleum-based plastics, can have a detrimental impact on aquatic ecosystems by disrupting the balance of microbes and killing off the animals that normally keep algae in check. The study compared the effects of conventional fossil fuel-based plastics and recently developed biodegradable plastics, finding that the petroleum plastics led to a rapid decline in zooplankton populations, which then allowed algae concentrations to spike and form harmful blooms.

Why it matters

Harmful algal blooms can force municipalities to close beaches and lakes due to public health risks, and have been linked to thousands of marine species deaths. This study suggests that plastic pollution may be exacerbating this growing global problem, beyond just the well-known issues of plastic accumulation and microplastic contamination.

The details

The study, published in the journal Communications Sustainability, involved a three-month experiment comparing 30 pond ecosystems with different types of plastics. Researchers found that in the tanks with conventional fossil fuel-based plastics, zooplankton populations immediately plummeted, allowing algae concentrations to spike. In contrast, the tanks with biodegradable plastics saw a much smaller impact on the zooplankton and other members of the ecosystem. The researchers also documented the emergence of distinct communities of bacteria growing in the presence of the plastic, though the exact cause is still unclear.

  • The study was conducted over a three-month period in 2025.

The players

University of California San Diego

The university where the research was conducted, including the Department of Ecology, Behavior and Evolution and the Department of Chemistry and Biochemistry.

Jonathan Shurin

A Biological Sciences Professor at UC San Diego and the senior author of the study.

Scott Morton

The first author of the study and a Biological Sciences graduate student at UC San Diego.

Michael Burkart

A Professor in the Department of Chemistry and Biochemistry at UC San Diego, and the founder and equity holder of Algenesis Materials, a company seeking to commercialize renewable materials.

Algenesis Materials

A UC San Diego spinoff company that develops and sells biodegradable plastic materials.

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What they’re saying

“We see all this plastic out there but how is it changing populations of algae, bacteria, seabirds or fish? We really don't know. We know algae blooms are partly due to nutrient pollution, but this study is showing that some of the algae blooms that we see around the world may also be due in part to the effects of plastic on the animals that normally control algae.”

— Jonathan Shurin, Biological Sciences Professor (Communications Sustainability)

“The petroleum plastic seemed to have a strong negative effect on the zooplankton populations. They seemed to either die off or reduce their reproduction very quickly. Bioplastic didn't have the same effect. That cascades down to the algae. In the petroleum tanks, fewer zooplankton consuming all that algae means you have more in the system and that leads to the algal blooms that we saw.”

— Scott Morton, Biological Sciences Graduate Student (Communications Sustainability)

“It is critical for us to understand how these new materials compare to traditional petroleum plastics when discarded in the environment. While all man-made objects have an impact on the planet, our goal is to minimize the ecological and health hazards of these now ubiquitous materials.”

— Michael Burkart, Professor, Department of Chemistry and Biochemistry (Communications Sustainability)

What’s next

The researchers are now further exploring their results by testing different types of biodegradable plastics, including "living plastic" filled with bacterial spores that break down the plastic material at the end of its life cycle.

The takeaway

This study highlights the significant and underappreciated impacts that plastic pollution can have on aquatic ecosystems, contributing to the growing global problem of harmful algal blooms. Transitioning to more biodegradable plastic alternatives could help mitigate these environmental hazards.