How coastal species are living on plastic debris in the ocean

Source– The post is based on the article “How coastal species are living on plastic debris in the ocean” published in “The Hindu” on 18th April 2023.

Syllabus: GS3- Environment

Relevance– Issues related to marine life and marine pollution

News– Recently, a study published by researchers from Canada, the Netherlands, and the U.S. have reported that coastal lifeforms have colonised plastic items in the Great Pacific Garbage Patch.

What are some facts about the Anthropocene epoch?

This is the name some scientists have proposed for a new period in history. It is characterized by the influence of Homo sapiens on the planet’s geology and ecosystems.

Scientists are still not clear when this epoch really began. Some candidates include the first nuclear weapon test and rapid industrialisation after the Second World War.

Some link it with the creation of plastic trash which is abundant in our urban refuse, rivers, and forests.

What are some facts about the great pacific garbage patch?

There are some water currents in the ocean that form loops. These are called gyres.

The North Pacific Subtropical Gyre is located just north of the equator in the Pacific Ocean. It consists of the Kuroshio, North Pacific, California, and North Equatorial currents and moves in a clockwise direction.

These currents flow adjacent to 51 Pacific Rim countries. Any trash that enters one of these currents, from any of these countries, could become part of the gyre.

Inside this gyre lies a long east-west strip. Here, some of the debris in these currents has collected over the years. The eastern part of this is the Great Pacific Garbage Patch. It is estimated to be 1.6 million sq. km big and more than 50 years old.

It contains an estimated 45,000-1,29,000 metric tonnes of plastic. It is predominantly in the form of microplastics. The more visible objects that haven’t yet broken down into smaller particles accounted for 92% of the plastics in 2018.

What are the findings of the study?

The tsunami off the Japanese coast in 2011 contributed to the debris in this garbage patch. Researchers had found debris on the West coast of North America containing live life forms originally found in Japan.

From November 2018 to January 2019, researchers collected 105 pieces of plastic debris from the eastern part of the NPSG. Based on the study, 98% of the debris items had invertebrate organisms.

They also found that pelagic species (species of the open ocean) were present on 94.3% of them and coastal species on 70.5%.

They found organisms belonging to 46 taxa. While 37 of them were coastal, the rest were pelagic. Among both coastal and pelagic organisms, crustaceans were the most common.

The coastal species were most commonly found on fishing nets whereas the pelagic species on crates.

Nearly all taxa were of Northwest Pacific origin, including Japan. Most debris items (85.7%) did not have identifiable markings linked to origin, such as manufacture locations or company/brand names.

The researchers also found that 68% of the coastal taxa and 33% of the pelagic taxa reproduced asexually. There was evidence of sexual reproduction among the hydroids and the crustaceans.

They reported a strong positive correlation between reproduction and mobility.

What is the relevance of the findings of the study?

The introduction of species on plastic items has given rise to a new kind of standing coastal community in the open ocean. Researchers have named it the neopelagic community.

The neopelagic community is not misplaced from other areas of the oceans but lives on plastic items in the garbage patch, including reproducing there.

As per another study polyethylene films had chemically bonded with rocks in China. This is reminiscent of the “anthropoquinas” of Brazil (sedimentary rocks embedded with plastic earrings) and the “plastiglomerates” of Hawaii (beach sediment + organic debris + basaltic lava + melted plastic).