The problem of Planet's underwater plastics detailed in a 60-year dataset

Scientists have discovered the first solid evidence that the amount of plastic polluting the oceans has increased dramatically in recent decades – by analyzing 60 years of logbooks for ships tracking plankton.

Data recorded by instruments known as Continuous Plankton Recorders (CPRs) – as vessels have collectively towed for several million kilometers across the Atlantic Ocean – show that trackers have become entangled in large plastic items, such as bags and fishing lines, about three times more often since 2000 than in previous decades.

This is the first time that researchers demonstrate the rise of ocean plastics with the help of a single set of long-term data, says Erik van Sebille, oceanographer at the University of Chicago. 39, Utrecht in the Netherlands. "I'm glad it's finally done," he says. The analysis was published¹ April 16th at Nature Communications.

The results are not surprising, but long-term data on ocean plastics are scarce: previous studies focused mainly on the ingestion of plastic by marine creatures on shorter time scales, the researchers say.

Fishing for data

CPRs are torpedo – like devices used since 1931 to study plankton populations by filtering water organisms with the aid of silk bands. Today, voluntary ships, such as ferries and container ships, tow a fleet of combat ships into the world's oceans.

But in recent years, devices have more often come back from the sea tangled in plastic, says Clare Ostle, biogeochemist of marine environments at the Marine Biological Association in Plymouth, UK, which oversees the aircraft fleet.

Whenever a ship tows a CPR, the crew fills out a logbook and notes any problem related to the aircraft. Ostle and his colleagues traveled all towing cranes in the North Atlantic between 1957 and 2016 to determine whether plastic entanglements had become more common.

During the 60-year period, 208 entanglements were recorded, some in the 1950s and 1960s. But since then, encounters with large plastic items, or macroplastics, have become much more common, multiplying in the 1980s and 1990s and culminating in the 2000s, when CPT became entangled in about 3% of traits (see "Plastic entanglements"). Fishing gear was the main culprit – involved in 55% of all entanglements.

Evidence Analysis

This increase is unlikely to result from a better record of entanglements: when the team analyzed the number of cardiopulmonary resuscitation encounters with natural objects, such as algae and fish, no significant changes occurred. occurred during the same period.

According to Van Sebille, the study of large plastic items, it does not reveal much about the amount of microplastics (fragments less than 5 millimeters long) in the oceans. These tiny contaminants come from sources such as disposable plastic packaging, rather than fishing gear.

Nevertheless, he adds, the study shows that fishing plays a major role in plastic pollution and will provide useful baseline data for determining whether policy changes are affecting plastic levels in the oceans. "As fisheries become more professional, especially in the North Sea, it is hoped that we will see a decrease," he says.