It’s been calculated that something in the order of four to 12 million tonnes of plastic waste enter the oceans every year, mostly through rivers.
She says understanding how plastic gets into fish matters not just to the fish, but to us. “We eat fish that eat plastic,” she says. “Are there things that transfer to the tissue? Does the plastic itself transfer to the tissue? Do the chemicals associated with the plastic transfer to the tissue?”
“One of the types of organisms that seems to be affected is crustacean zooplankton, which are the main prey for many small fishes,” said Höök, whose findings were published in the journal Science of the Total Environment. “The fact that these very small organisms are consuming these microplastics, altering their growth, reproduction and survival, means there could be consequences up the food web. If zooplankton numbers decline, there may be less food available for organisms at higher trophic levels.”
“Microplastic particles were found throughout all cores sampled … It suggests that microplastics are now ubiquitous within the surface waters of the world’s ocean. Nowhere is immune.”
“Given their pervasive and persistent nature, microplastics have become a global environmental concern and a potential risk to human populations,” said Rachel Hurley from the University of Manchester and colleagues in their report, published in Nature Geoscience.
“Microplastics have been found in mussels everywhere scientists have looked,” she said.
More than five trillion pieces of plastic are estimated floating on the surface of the world’s oceans. It has been claimed that there is now enough plastic to form a permanent layer in the fossil record.
“… plastic debris is often contaminated with toxic chemicals. Plastics can absorb and concentrate toxic pollutants present at trace levels in seawater, and some of the chemical additives mixed in during the manufacturing process can be toxic as well. When marine organisms ingest chemical-laden plastic pieces, some of the pollutants may be released within the gut of the animal and absorbed into body tissue. Although it is uncertain how much of these harmful chemicals enter marine animals due to ingestion of plastic debris in the ocean, laboratory experiments suggest there may be reason for concern.”
The researchers then observed the oysters’ physiological responses to ingesting the microplastics. The most obvious effect was on reproduction. Oysters that were exposed to microplastics produced fewer and smaller egg cells and slower sperm. Exposed oysters also produced fewer larvae and their offspring tended to grow more slowly.