By Belén Delgado
The latest studies on the matter indicate that up to 529 wild species have been entangled in marine debris or affected by its ingestion, a mortal risk that adds to those that dozens of them already face in danger of extinction.
No matter how small, microplastics (up to five millimeters in diameter and present in many products such as cosmetics) are part of that threat to the more than 220 species that absorb them, some as important in trade as mussels, prawns , lobsters, sardines or cod.
A recent report by the UN Food and Agriculture Organization (FAO) has compiled what is known about the implications of these wastes for fisheries and aquaculture.
"Although we are concerned about the ingestion of microplastics by people through fish and shellfish, we currently have no scientific evidence to corroborate harmful effects in wild animals," explains one of its authors, researcher Amy Lusher, to EFE.
He estimates that many years of research are still missing, given the information gap that exists and the many inconsistencies in the available data.
Mistaking plastic for food
To contribute to the debate, the Royal Society of London journal of biology recently published a study that suggests that certain fish are predisposed to mistake plastic for food because they give off a similar smell.
Matthew Savoca, leader of the work carried out in collaboration with an aquarium in San Francisco (United States), explains that they presented solutions to several groups of anchovies with the smell of plastic waste collected from the sea and others with that of clean plastics.
The anchovies responded to the garbage in a similar way as they would to their food because these remains are covered with biological material such as algae that mimics the smell of food, which would rule out that they act accidentally.
"Many marine animals depend a lot on their smell to find their food, much more than humans," says Savoca, who argues that plastic "seems to fool" the animals that find it in the sea, being "very difficult for them to see that it is not a food ”.
If the causes of the ingestion are still not entirely clear, neither are its repercussions.
FAO recalls that the adverse effects of microplastics on marine fauna have been observed in laboratory experiments, usually with a degree of exposure to these substances "much higher" than that found in the environment.
In the wild, these particles have only appeared in the digestive system of wild organisms, which people "usually remove before consuming," says Lusher.
Those who eat some small fish or most bivalves whole may be more exposed, according to the FAO, which collects the worst case estimate, that of a portion of 225 grams of mussels that would take 7 micrograms of plastic (equivalent to less than 0, 1% of the total daily intake).
Always in the worst of forecasts, a problem would be given by the presence of polluting substances and additives that are added to plastics during their manufacture or are absorbed in the sea, although data on their impact and on that of plastics are lacking. small in food.
Study more the distribution of plastics
In the opinion of scientists, it will be necessary to study more in depth the distribution of these residues at a global level, no matter how much they move from one place to another, and the accumulation process to which fishing and aquaculture contribute when their plastic equipment they end up lost or abandoned.
In a world increasingly flooded with plastics (up to 322 million tons produced in 2015), it is estimated that pollution will continue to increase in the oceans, where in 2010 between 4.8 and 12.7 million tons of this type were dumped of garbage.