PLASTIC DEBRIS IN THE OCEAN

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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