Real-world examples of biodegradable plastics & marine life impact

Examples of biodegradable plastics & marine life impact in the real world

The best way to understand biodegradable plastics is to look at how they behave once they escape into rivers and oceans. Below are real examples of biodegradable plastics & marine life impact drawn from peer-reviewed studies and field data, not just lab tests or marketing.

1. PLA shopping bags: biodegradable in theory, persistent in the ocean

Polylactic acid (PLA) is one of the most widely used “biodegradable” plastics. It’s made from plant sugars (often corn in the U.S.), then turned into shopping bags, food containers, and disposable cutlery.

On land, under industrial composting conditions (high heat, controlled moisture, active microbes), PLA can break down relatively quickly. But several examples of biodegradable plastics & marine life impact show that PLA behaves very differently in seawater.

Researchers working with the U.S. National Oceanic and Atmospheric Administration (NOAA) and other institutions have found that PLA degrades extremely slowly in cold marine environments. In some tests, PLA items showed little to no measurable breakdown over many months in seawater, while conventional polyethylene bags also persisted. That means a PLA bag that blows off a boat or out of a coastal landfill can still float, snag on coral, or be ingested by marine animals just like a regular plastic bag.

Sea turtles, which often mistake drifting bags for jellyfish, don’t care whether the polymer is petroleum-based or plant-based. To them, it’s the same shape, the same movement in the water column, and the same risk of gut blockage or starvation.

2. “Biodegradable” plastic bags that still look new after years at sea

A frequently cited example of biodegradable plastics & marine life impact comes from long-term weathering studies of retail bags labeled as “biodegradable,” “oxo-biodegradable,” and “compostable.”

In one study by UK researchers, bags were buried in soil, left in open air, and submerged in seawater for up to three years. Some bags labeled as biodegradable were still strong enough to hold groceries after years in the natural environment. In seawater, many of the samples—whether conventional or “biodegradable”—remained largely intact, even if they became brittle or discolored.

From a marine life perspective, a bag that is brittle but still bag-shaped is still a hazard. Seabirds can become entangled, and marine mammals can accidentally ingest the film while feeding. This is a powerful example of how biodegradable claims can mislead consumers into thinking littering is less harmful, even when the marine life impact is similar.

3. PHA fishing gear: promising, but not a silver bullet

Polyhydroxyalkanoates (PHAs) are often held up as one of the best examples of biodegradable plastics & marine life impact that might actually reduce harm. PHAs are produced by microbes and can be engineered to break down in a wider range of environments, including seawater.

A growing number of projects are testing PHA-based fishing gear—such as nets, lines, and pots—as alternatives to conventional nylon or polyethylene gear that can ghost fish for years after being lost. Lab and mesocosm experiments have shown some PHA formulations can significantly degrade in marine conditions over months to a few years, rather than decades.

However, even these more promising examples of biodegradable plastics & marine life impact come with caveats:

• Degradation rates depend heavily on temperature, microbial communities, and thickness of the material.
• Before they break down, lost PHA nets can still entangle fish, turtles, and marine mammals.
• As PHA gear fragments, there’s a window of time when micro-sized particles are present and potentially ingestible by plankton and filter feeders.

So while PHA fishing gear is an encouraging direction, it has to be paired with better gear recovery and fishing practices, not just a switch in material.

For a high-level overview of marine debris and lost fishing gear, NOAA’s Marine Debris Program is a useful starting point: https://marinedebris.noaa.gov

4. Coffee pods and food packaging labeled compostable

Another real example of biodegradable plastics & marine life impact comes from compostable coffee pods, snack wrappers, and food service packaging. Many of these products are made from blends of PLA and other biopolymers, sometimes with paper or fiber layers.

In an ideal system, these items are collected separately, processed in an industrial composting facility, and never see the ocean. In the real world, mis-sorting is common. Compostable pods tossed into regular trash can escape from landfills, and pods tossed into recycling streams often end up as contamination.

Once in waterways, these multi-layered materials rarely behave like they do in a controlled composting environment. The outer paper or fiber layer may soften or peel away, while the plastic layer persists. Fish and invertebrates can peck at or ingest these fragments, particularly when food residues remain attached.

A 2023–2024 trend in the U.S. and Europe is stricter labeling rules for compostable packaging, aimed at reducing confusion and limiting greenwashing. This reflects growing recognition that many examples of biodegradable plastics & marine life impact are driven not by the material alone, but by how products are labeled, collected, and managed.

For guidance on labeling and claims, the U.S. Federal Trade Commission’s Green Guides are a key reference: https://www.ftc.gov/system/files/documents/public_events/1589803/ftc_green_guides.pdf

5. Agricultural mulch films washing into coastal waters

Biodegradable mulch films used on farms are often promoted as a way to reduce plastic waste, because they can be tilled into soil instead of removed and landfilled. These films are typically made from blends of PLA, PBAT (polybutylene adipate terephthalate), and other biopolymers.

In practice, storms and irrigation runoff can carry fragments of these films into drainage ditches, rivers, and eventually estuaries and coastal zones. Once there, the conditions are very different from warm, microbe-rich agricultural soils.

Some field monitoring campaigns in Europe and North America have found mulch film fragments in river sediments and coastal beaches downstream of intensive agriculture. These are emerging examples of biodegradable plastics & marine life impact on benthic organisms, such as worms, crustaceans, and small fish that live and feed in or near the sediment.

While research is still developing, early studies suggest that even partially degraded mulch film fragments can alter sediment structure and potentially interfere with feeding behavior of small invertebrates. That means “soil-biodegradable” does not automatically translate to “marine-biodegradable.”

6. Biodegradable microbeads and cosmetic ingredients

Microbeads in cosmetics are a classic case where regulation changed the market fast. The U.S. banned plastic microbeads in rinse-off cosmetics under the Microbead-Free Waters Act of 2015, which prompted many companies to switch to natural abrasives like salt, sugar, or ground nutshells.

However, some products globally have experimented with “biodegradable” polymer beads or capsules. These tiny particles can still enter wastewater and reach rivers and oceans if treatment systems are overloaded or outdated.

At micro scales, the marine life impact is less about entanglement and more about ingestion. Zooplankton, larvae, and filter-feeding shellfish can ingest micro-sized particles regardless of whether they’re petroleum-based or biobased. This is another example of biodegradable plastics & marine life impact where the particle size and behavior in water matter far more than the marketing label.

For background on microplastics and health, the U.S. National Institute of Environmental Health Sciences offers accessible summaries: https://www.niehs.nih.gov/health/topics/agents/microplastics

7. Biodegradable food-service items on beaches and in coastal tourism

Coastal tourism hotspots provide very visible examples of biodegradable plastics & marine life impact. Beach cleanups from California to Florida and Hawaii increasingly report items labeled “compostable” or “biodegradable” among the litter: cups, straws, cutlery, takeout containers, and bags.

On a hot beach, these items can soften or crack, but they rarely vanish. Wind moves them into dunes and nearshore waters. Once in the surf zone, they behave like any other light plastic: they float, tumble, and break into smaller pieces.

Sea birds often target food-contaminated items, tearing at lids and containers. Fish and invertebrates can interact with fragments in the wrack line. These are highly visible, everyday examples of biodegradable plastics & marine life impact that challenge the assumption that switching material alone solves the litter problem.

8. Biodegradable plastics in aquaculture and shellfish farms

Aquaculture—especially shellfish farming—sometimes uses biodegradable clips, ties, or mesh components designed to reduce long-term plastic pollution. Some pilot projects in Europe and Asia have tested PHA or starch-based materials for oyster and mussel farming.

These trials provide nuanced examples of biodegradable plastics & marine life impact:

• When gear performs well and breaks down after its useful life, there is less persistent plastic left in the environment.
• If the material fails too early, farmers may add more gear or switch back to conventional plastics.
• Fragments from partially degraded gear can settle in sediments around farms, where they may be ingested by deposit-feeding worms and small crustaceans that form the base of the food web.

This is a reminder that performance and longevity in real-world marine conditions are just as important as biodegradation rates.

Why most biodegradable plastics don’t behave like you expect in the ocean

Across all these examples of biodegradable plastics & marine life impact, a pattern emerges: materials that degrade in industrial composters or warm, microbe-rich soil often do not break down quickly in cold, salty, oxygen-rich seawater.

Key reasons include:

• Temperature: Many biodegradation tests are run at 122°F (50°C) or higher. Most oceans are far colder.
• Microbial community: The microbes that break down PLA or PBAT in compost are not always abundant in open water.
• Oxygen and light: UV radiation and oxygen can make plastics brittle, but that doesn’t mean they mineralize into CO₂ and water. They often just fragment.

From a marine life perspective, fragmentation can actually increase exposure, because more organisms can interact with smaller pieces.

2024–2025 trends: stricter standards and “marine biodegradable” claims

Governments and standards bodies have started to respond to misleading claims. Two trends stand out in 2024–2025:

• Tighter labeling rules. The European Union and several U.S. states are moving toward clearer restrictions on terms like “biodegradable,” especially when products are likely to end up as litter. Regulators want proof that a product biodegrades in the environment where it’s marketed to be safer.
• New marine biodegradability standards. There is growing interest in test methods that simulate real marine conditions. Some industry groups now promote materials that meet “marine biodegradable” criteria, but independent scientists caution that these tests are still simplified compared to complex, variable ocean ecosystems.

As these standards evolve, expect more scrutiny of marketing claims. The best examples of biodegradable plastics & marine life impact going forward will likely come from long-term field data, not just lab certificates.

How to interpret “biodegradable” claims as a consumer or policymaker

If you’re trying to reduce harm to marine life, a few practical guidelines help cut through the noise:

• Assume any plastic-like item can harm marine life if littered. Whether it’s labeled biodegradable, compostable, or plant-based, the risk of entanglement and ingestion remains as long as the item is physically present.
• Look for clear disposal pathways. Industrially compostable items only make sense where there is actual access to industrial composting and separate collection.
• Prioritize reuse and reduction. Reusable bags, bottles, and containers consistently outperform single-use items, even when those single-use items are made from biodegradable plastics.
• Support better waste management and fishing practices. Many of the worst examples of biodegradable plastics & marine life impact occur where collection, recycling, and gear recovery systems are weak.

For broader context on plastic pollution and marine ecosystems, the U.S. Environmental Protection Agency offers educational resources here: https://www.epa.gov/trash-free-waters

FAQ: Biodegradable plastics and marine life

Are there any good examples of biodegradable plastics that truly reduce marine life impact?
Some of the best examples are still in pilot or early commercial stages, such as certain PHA-based fishing gear and aquaculture components that show faster breakdown in seawater than conventional plastics. Even then, they only reduce marine life impact when combined with better gear management and retrieval. Material choice alone is not enough.

Can a single example of a biodegradable plastic product be considered “ocean-safe”?
Not reliably. A product might perform well in one test location or lab study, but ocean conditions vary widely by temperature, depth, and microbial community. Until multiple independent studies show consistent behavior, it’s risky to label any specific example of biodegradable plastic as universally “ocean-safe.”

Do biodegradable plastics still create microplastics in the ocean?
Yes, many do. Before they fully biodegrade—if they biodegrade at all—they often fragment into smaller pieces. Those fragments can behave like microplastics and be ingested by plankton, shellfish, and small fish. Several real examples of biodegradable plastics & marine life impact involve these intermediate fragments rather than intact items.

What are some examples of better choices for consumers concerned about marine life?
Choosing durable, reusable products—like metal or glass bottles, sturdy shopping bags, and reusable food containers—avoids many of the problems shown in examples of biodegradable plastics & marine life impact. When disposables are unavoidable, paper or fiber-based items that are uncoated or minimally coated and can break down in a wide range of environments are often preferable, provided they are sourced from responsibly managed forests.

If a product is labeled compostable, is it safe if it ends up in the ocean?
No. “Compostable” generally refers to industrial composting conditions, not seawater. Many compostable plastics behave similarly to conventional plastics when they escape into rivers and oceans. Several of the examples of biodegradable plastics & marine life impact discussed above involve compostable products that became litter and persisted long enough to interact with wildlife.

How should policymakers use these examples when designing regulations?
Policymakers can treat these real examples of biodegradable plastics & marine life impact as evidence that material substitution alone is not a reliable strategy. Regulations that focus on source reduction, reuse systems, deposit-return schemes, better fishing gear management, and accurate labeling will likely have far more impact than simply encouraging a switch from conventional to biodegradable plastics.