Toxic materials a concern for freshwater ecosystems
By Summit Voice
FRISCO — By now, everyone has heard about the giant ocean eddies of plastic debris — the final resting place, as it were, for the detritus of our throw-away society. As it turns out, the ocean isn’t the only place that’s been polluted by human thoughtlessness.
German scientists say their recent study of Lake Garda, a subalpine lake at the southern edge of the Italian Alps, is also polluted with potentially hazardous plastics. The findings are a warming sign that many other freshwater lakes may be similarly polluted, and that those tiny microplastics are likely finding their way into the food web through a wide range of freshwater invertebrates, too.
“Next to mechanical impairments of swallowed plastics mistaken as food, many plastic-associated chemicals have been shown to be carcinogenic, endocrine-disrupting, or acutely toxic,” said Christian Laforsch of the University of Bayreuth in Germany. “Moreover, the polymers can adsorb toxic hydrophobic organic pollutants and transport these compounds to otherwise less polluted habitats. Along this line, plastic debris can act as vector for alien species and diseases,” LaForsch said.
Other recent research shows that the well-known ocean garbage patches have become microbial reefs, where untold multitudes of organisms have found a new home.
The researchers chose Lake Garda as a starting point for investigating freshwater contamination with micro- and macroplastics because they expected it to be less polluted given its subalpine location. What they found was a surprise: The numbers of microplastic particles in sediment samples from Lake Garda were similar to those found in studies of marine beach sediments.
The size ranges of microplastics found by Laforsch’s team suggested that they might find their way into organisms living in the lake. Indeed, the researchers showed that freshwater invertebrates from worms to water fleas will ingest artificially ground fluorescent microplastics in the lab.
The findings in Lake Garda come as bad news for lakes generally, with uncertain ecological and economic consequences.
“The mere existence of microplastic particles in a subalpine headwater suggests an even higher relevance of plastic particles in lowland waters,” Laforsch said. He recommended more research and standardized surveillance guidelines to control for microplastic contamination in freshwater ecosystems, as is already required for marine systems.
The shape and type of plastic particles found in the study indicate that they started as larger pieces of plastic, most likely originating from post-consumer products.
The findings were reported on October 7th in Current Biology, a Cell Press publication.