Fiberglass Contamination Found at 96% of Sediment Sites in a Vancouver Island Estuary
The conversation around contaminants in coastal ecosystems has focused heavily on microplastics. A study from Simon Fraser University points to a different particle that has received almost no regulatory attention: fiberglass. The material - silica-based glass fibers, often embedded in plastic resin - is used in boat hulls, marine infrastructure, and construction materials across the world's coastlines. As boats age, are sanded during repair, or are abandoned to decay, those fibers break into needle-like fragments and enter surrounding waters.
At the Cowichan Estuary on Vancouver Island, fiberglass is now pervasive. A study published in Marine Pollution Bulletin found fiberglass particles at 96% of sediment testing stations sampled in 2023, up from 64% of sites in 2020 - one of the first baseline assessments of coastal fiberglass contamination in Canada.
Where the Particles Are Concentrated
The study sampled 26 sites across the Cowichan Estuary between 2020 and 2024, analyzing both surface biofilm - the thin layer of algae and microorganisms that fuels migratory shorebirds - and deeper sediment where clams, mussels, and other invertebrates live.
Sediment concentrations ranged from 6 to 286 particles per kilogram of dry sediment, with the highest levels near industrial activity and a log transport channel. Fiberglass is denser than saltwater and tends to settle into sediment layers. Biofilm concentrations of 30 to 62 particles per kilogram were found at sites near the Western Forest Products mill pond, the Westcan Terminal, and a Cowichan Bay marina - implicating boat maintenance activities and industrial runoff as primary sources.
"Fiberglass particles are silica-based glass fibres, often reinforced with plastic, and we are just in the infancy of understanding their potential toxicity for animals and people," said Juan Jose Alava, marine eco-toxicologist and lead author at SFU.
Why This Estuary Matters
The Cowichan Estuary is a 400-hectare intertidal ecosystem used by the Cowichan Tribes First Nations for generations - internationally designated as an important bird area - supporting harvesting of clams, geoducks, crabs, waterfowl, cod roe, urchins, and salmon. Migratory shorebirds feed on the biofilm layer where some of the highest fiberglass concentrations were measured.
"Just knowing these particles are present in an estuary that supports shorebirds and shellfish - and is central to Indigenous food security - is enough to justify preventive, precautionary actions," Alava said. Whether fiberglass bioaccumulates through the food chain is not yet established, nor is the toxicological threshold at which exposure causes harm in marine invertebrates, birds, or humans.
Recommendations
The study recommends tighter controls on boat yards to reduce sanding debris entering water; stronger regulations for end-of-life boat disposal including recycling requirements for fiberglass hulls; improved stormwater management at coastal industrial sites; and investment in environmentally safer hull materials. Abandoned and deteriorating vessels are flagged as an underappreciated persistent source - their slow dissolution into fiberglass particles has not been integrated into contamination management frameworks. The contamination documented in 2023 already represents a meaningful increase over 2020 baseline measurements.