Short Note: South Pacific Gyre and Pollution in Henderson Island

Recently, scientists found that Henderson Island, one of the remotest islands discovered so far, was covered with an estimated 38 million pieces of trash at its coast. The major concern for the scientists was that what made the remotest and uninhabited island a plastic junkyard.

Researchers say that the South Pacific Gyre, a component of earth system of rotating ocean currents, is responsible for the collection of such huge density of thrash on the island. The South Pacific Gyre carries with it the debris from South America, or those dumped by the fishing boats, and then deposits the debris at the coast of the island.

What is an ocean gyre and how is it formed?

Ocean gyre is any large system of circulating ocean currents, especially those involved with large wind movements. For example, South Pacific Gyre, Northern Indian Ocean Gyre, etc.

There are three forces that are responsible for the circulation of a gyre viz. Global Wind Pattern, Coriolis Effect & Earth’s Land Masses. Wind drags the ocean surface, causing the water to move in the direction of the wind. The deflection of a moving object on earth due to earth’s rotation is called Coriolis Effect. It is capable of deflecting the ocean currents by angles of about 45 degrees. Ocean gyre is also influenced by the extent of landmasses to which it is surrounded. For example, the South Pacific Gyre is large ocean gyre and includes hundreds of kilometers of Open Ocean and very less influence of land masses; on the other hand north Indian Ocean Gyre is a much smaller ocean gyre and is widely influenced by the land masses.

What is it causing worry for scientists?

As per recent report presented at World Economic Forum, 14% of the plastic is recycled, 40% of plastic is going into landfills and the rest of the plastic trash is dumped into the seas or oceans. This plastic debris injures and kills fish, seabirds and marine mammals. It also creates physical barriers on beaches to animals such as sea turtles, and other invertebrates. Nearly 200 marine species and about 55 percent of the population of seabirds’, including those endemic to Henderson Islands, are at risk due to eating of plastic debris.

Facts about Henderson Island

This Island is located in the South Pacific Ocean about halfway between New Zealand and Chile and is recognised as a UNESCO world heritage site.  This island is visited by humans only once every five to 10 years for research purposes. It is one of the world’s last two raised coral atolls (other being Aldabra Island in the Indian Ocean) whose ecosystems remain relatively unaffected by human contact. As per research published in April 2017, the island consists of the highest density of plastic rubbish than anywhere in the world.

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