Pollution in the South Pacific Ocean affects Rapa Nui

Pollution in the South Pacific Ocean affects Rapa Nui

Pollution in the South Pacific Ocean affects Rapa Nui

by Raquelle de Vine
& Charles Moore

Late last December, the Marine Research Foundation Algalita (California, USA) arrived on Easter Island. The director of the institution, the scientist Charles Moore, was the discoverer, in 1997, of the “Island of Plastic” which is forming in the North Pacific Ocean between Hawaii and the North American continent. It is as big as Central Europe and weighs nearly 3 million tons. Sad to say, since that discovery, similar accumulations of floating plastic rubbish have been found in the center of all the oceans of the world, with our South Pacific Ocean no exception. His new mission is to determine how much rubbish – especially plastic – is now in the South Pacific between the coast of Chile and Easter Island. He is accompanied by a group of Scientists of Rubbish from the Catholic University of the North.
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There was a low misty cloud blanketing the island on 19 December 2016 as we came upon the northern point of Rapa Nui. It was early hours in the morning and the crew of the ORV Alguita were all on deck elated by the sight of the island and the Moai of Ahu Tahai standing tall upon the coastline. Seventeen days prior, we had set sail from the Galapagos archipelago after initially leaving from Long Beach, California on 2 November 2016. The purpose of the voyage? For Algalita Marine Research and Education, to sample floating plastic pollution in the South Pacific Ocean, with a special focus on the South Pacific Subtropical Gyre.
Rapa Nui’s central location within the great South Pacific Ocean also puts it in the central area of the enormous system of currents known as a gyre. The South Pacific Gyre is a system of circular ocean currents formed by the patterns of the earth’s winds and rotational forces. It stretches from Australia to South America. The circular motion of the currents rotates counter-clockwise combining four of the main currents, creating a central convergence zone of the ocean surface and everything on it.

A water bottle lost down the drain in Sydney or a fishing buoy lost overboard in Peruvian waters can find its way into this central accumulation area, or the shores of Rapa Nui – most likely photodegraded, weathered and /or overgrown by marine organisms but all the same it is there, because plastic biodegrades over time scales of decades or longer. This central convergence of marine plastic debris is what has attracted Algalita for their 2016/2017 Expedition. Since 1999, two years after sailing through part of the North Pacific Subtropical Gyre, now commonly referred to as “Great Pacific Garbage Patch,” Captain Moore and the ORV Alguita have returned there ten times. Each time they have been monitoring the plastic pollution within it. This 2016/17 voyage is to begin monitoring and comparison with the South Pacific Gyre.

Gyres are indicative of the state of the debris in the oceans due to the concentration of accumulated debris. Like spilling rice all over the floor and then sweeping it up into a pile, the pile gives you an idea of how much was spilled. The expanse of the ocean is far too great to be able to understand the extent of the problem within our life time if we just picked each grain up, grain by grain.
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To gather the information from the Gyre which will allow us a better understanding of the state of the South Pacific Ocean, Algalita uses a device known as a Manta Trawl. Specifically designed for the purpose of zooplankton and micro-plastic (<5mm) sampling, it allows us to gather samples from the Neuston (surface) layer of the ocean in a fine-meshed net. We drop the Manta Trawl for about 30 minutes up to twice a day, every day, dependent on ocean conditions.

By the time the expedition arrived in Rapa Nui we had conducted 40 trawls, however this was only the beginning. We took refuge at Rapa Nui for the holiday period and to prepare for the crossing to Mainland Chile, via the gyre, we also conducted a week-long sampling in the offshore waters. During our time we enjoyed great hospitality and kinship from the locals, particularly Christian Rapu and Sebastian Yankovic-Pakarati.

Sebastian joined the crew along with Juan Pablo Muñoz-García from Galapagos Islands and Tim Kiessling from the Nucleo Milenio ESMOI and Magdalena Gatta from Scientists of Rubbish. During the week of sampling around Rapa Nui, we conducted several more trawls and collected a variety of larger debris, which allows for a record of any identifiable items and their potential sources, as the main percentage of plastic debris in the ocean is in micro form. Microplastic debris can come from cosmetics such as microbeads but most are fragments of larger plastic items that have degraded and broken down. As you may have experienced if you are sifting through the sands of Anakena beach on Rapa Nui, the tiny plastic fragments of debris you find contaminating the natural sand could have come from anywhere! But finding a complete item, before the sun, wind, waves or organisms have broken it down or eaten away at it, gives us more of an idea of where the debris might be coming from.

Upon arriving in the surrounding waters of Rapa Nui, we experienced greater and greater quantities of plastic litter and densities which didn’t start to decrease until we were much further East, near the Island of Robinson Crusoe. Both within the waters around Rapa Nui and crossing the South Pacific Gyre, our trawl samples were coming in thick with plastic micro fragments, filament and fishing line – the South Pacific’s very own Plastic Soup. Captain Moore’s subjective feeling of the extent of accumulation of the microplastic debris likens it to the samples they were taking in 2007 in the North Pacific gyre. This was unexpected to him, as in 2011 when Algalita collaborated on an initial study of microplastics in the South Pacific Subtropical Gyre, the total quantity of microplastics gathered in samples could be held in a single hand…. This is no longer the case.

The comparison of larger litter to the North Pacific Gyre has also been interesting as the majority of identifiable objects found in the North Pacific Gyre are consumer goods, whereas during our current collection only 22.5 % has been consumer goods, 52% has been related to industrial fisheries, and the rest was unidentifiable. Most items were buoys, lines, ropes, buckets, fuel/oil containers and fish bins. We even hauled in a lone ghost net drifting along and discovered a disused FAD, Fish Aggregation Device. This is an artificial object which is used to attract deep sea fish, such as marlin, tuna and mahi-mahi (dolphin fish). Generally they are found on buoys or floaters that are attached to the ocean floor by blocks of cement. The fish are fascinated by any floating object, so these can be used to mark their breeding grounds. More than 300 species of fish will gather around the FAD, which are used both for recreational and commercial fishing. Alguita, together with organizations in Rapa Nui, is demanding that the nations of the world take effective measures to reduce the contamination in the oceans and to protect the still pristine ecosystems, such as the waters around Rapa Nui.

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