No plastics left behind: study confirms plastic beach debris a danger to ocean life

This plastic bag doesn't look dangerous, but plastics pose a significant risk to aquatic ecosystems. Dr. Leah Bendell looks into plastics as a source of trace metals and a concern for intertidal food webs.

February 14, 2018

At current rates of plastic production, by 2050 the total mass of plastics in our oceans will outweigh the biomass of fish.  — World Economic Forum

Last summer, Bertrand Munier spent four weeks picking up plastic debris from nine beaches along Burrard Inlet in Vancouver, B.C..  He photographed and collected every piece of plastic debris within a 1-km X 10-meter strip of mid-tide beach and ended up with 150 items.

Munier, an environmental engineering student on a study exchange from Lyon, France was carrying out research under the supervision of biological sciences professor Leah Bendell.

Myriad studies have shown that plastic particles present significant risks to aquatic ecosystems and the humans who rely on these ecosystems. But Bendell wanted to dig deeper and determine the potential role of both macro (more than 5mm) and micro plastics (less than 5mm) in providing a source of trace metals, zinc, copper, cadmium and lead to intertidal food webs.

She was staggered by the diversity of objects Munier collected. Items ranged from children’s toys, bicycle parts and personal hygiene items to food packaging.

The collected debris was characterized for its polymer type, then subjected to a weak acid extraction to remove zinc, copper, cadmium and lead from the polymer. Fourteen different plastic types were identified, the most abundant being PVC polyvinyl chloride, the third most widely produced plastic polymer.

Says Bendell, “We found some items carried extremely high concentrations of copper, lead, zinc and cadmium while all items carried traces of the four metals.”

She explains that plastics introduce trace metals to intertidal ecosystems in three ways:through direct release into the water as a consequence of leaching from the plastic itself, entry into food webs through ingestion of plastic particles and the metals sorbed onto the plastics by small organisms at the bottom of the food chain, and as a point source of toxic metal exposure to coastal ecosystems.

Bendell urges the public to be aware of the dangers posed by plastics in aquatic environments.

“The World Economic Forum estimates that at current rates of plastic production, by 2050, the total mass of plastics in our oceans will outweigh the biomass of fish,” she says.

“Even something as innocuous as a child’s toy left on the beach will provide a sorption site for metals, which will then break down into fragments that could then allow the entry of toxic metals into coastal food webs.”

Her next research project focuses on the effect that dyes in plastics may have on coastal ecosystems and food webs.


This study was published today in the journal PLOS ONE