PLASTIC DEBRIS IN THE OCEAN

sree nivas April 18, 2023 Environmental Issues, GS3 Leave a comment 160 Views

The Anthropocene epoch – This is the name some scientists have proposed for a new period in history characterised by the influence of one species on the planet’s geology, ecosystems and even its fate — none other than Homo sapiens.

Key details:

The North Pacific Subtropical Gyre (NPSG) have a long east-west strip where some of the debris of plastics in these currents has collected over the years.
The eastern part of this is the Great Pacific Garbage Patch.
It is, per one estimate, 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, predominantly in the form of microplastics.
Mass-wise, heavier, more visible objects that haven’t yet broken down into smaller particles accounted for 92% of the plastics in 2018.

Contribution of the Tsunami:

The tsunami off the Japanese coast in 2011 contributed to the debris in this garbage patch.
Until at least 2017, researchers had found debris washing ashore on the West coast of North America containing live lifeforms originally found in Japan.
Researchers reported that 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%.
That is, organisms found on coasts were getting by on small floating islands of garbage (to humans) out in the Pacific Ocean.
The number of coastal species such as arthropods and molluscs identified rafting on plastic was over three-times greater than that of pelagic species that normally live in the open ocean.
In all, they found organisms belonging to 46 taxa.
While 37 of them were coastal, the rest were pelagic.
Pelagic means relating to or living in areas of the sea away from the land
Among both coastal and pelagic organisms, crustaceans were the most common.
Nearly all taxa were of Northwest Pacific origin, including Japan.

The relevance of the findings

A new community:

The introduction of a vast sea of relatively permanent anthropogenic rafts since the 1950s has given rise to a new kind of standing coastal community in the open ocean.
Researchers have named it the neopelagic community.

A new settlement:

While coastal species have been found on human-made objects in the open ocean before, they were always considered to have been “misplaced” from their intended habitats.
The neopelagic community, on the other hand, is not misplaced but lives on plastic items in the garbage patch, including reproducing there.

Bonding of plastics with nature:

Polyethylene films had chemically bonded with rocks in China.
Anthropoquinas of Brazil (sedimentary rocks embedded with plastic earrings)
The “plastiglomerates” of Hawai’i (beach sediment + organic debris + basaltic lava + melted plastic).

SOURCE: THE HINDU, THE ECONOMIC TIMES, PIB

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