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5 September 2022
On one of the most isolated islands in the world, the beaches are full of plastic. So much plastic that it acts like an insulation blanket. Plastic strongly affects the daily temperature cycle of the sand. During the day the sand is a few degrees warmer than normal, and at night it is cooler. The animals that live here are being affected by it.
Henderson Island is situated between Chile and New Zealand, thousands of kilometres from the civilised world. Nobody lives on the island and it is protected as a UNESCO world heritage site because of its unique flora and fauna.
PLASTIC WARMS UP BEACHES
In 2019, researchers took the temperature of the sand of the beaches of Henderson Island (and Cocos, another island) at different places and times every day. It turned out that the plastic was causing the maximum temperature of the top layer to be 2.45 degrees Celsius higher than normal during the day and an extra 1.5 degrees cooler at night. This has consequences for animals, especially for cold-blooded animals that cannot regulate their own body temperature, and for the meiofauna which are organisms that live in the sand.
This is not a previously described phenomenon that is caused by plastic pollution. The findings are in the Journal of Hazardous Materials. Also read this summary and this interview with one of the researchers.
HENDERSON ISLAND, THE MOST POLLUTED PLACE IN THE WORLD
This was a follow-up to previous research. In 2017, Henderson Island became world news. The same researchers had counted the plastic. They found 38 million pieces of plastic, or almost 700 pieces per square metre of beach. Nowhere else in the world is there a higher density of plastic waste and that at the same time is so far from human habitation. The plastic is brought here by the South Pacific Gyre, the current that circulates in enormous anti-clockwise circles in the southern part of the Pacific Ocean.
The scientists returned in 2019 and published more findings. The number of microplastics appeared to have risen sharply in the intervening four years. They also observed that in the top 5 cm of sand on one single beach there were more than 4 billion nanoplastics (smaller than 0.001 mm).
DANGEROUS FOR ANIMALS
It is known that plastic causes all sorts of problems for animals. Larger animals get caught in nets and drown or starve. Dolphins, sea turtles and seals either get entangled in plastic while playing with it or they see plastic as food. Hermit crabs that use plastic containers or lids to live in burn in them. Miniscule plastic particles (nanoplastics) can enter any organism, from plankton to whales. There is now an additional threat: the change in the temperature of beach sand.
DOES CLEANING UP HELP?
In June 2019, another team went to Henderson to clean up and analyse the items. In 11 days they collected six tonnes of plastic waste on just a 2.5 km stretch of beach on the east side of the island. Of this, 60% came from industrial fishing and included 1,200 fishing buoys and a lot of nets. Other items came from 25 countries and included bottles from Japan, Scotland and Puerto Rico, and even a rubber boot made in the Netherlands.
The rubbish was gathered together above the high tide line in 13 places. Poor weather conditions made it impossible to remove. Sailing back to the island to collect all that plastic is extremely expensive and it would have to be shipped thousands of kilometres to the mainland. That rubbish is still lying there in 13 piles.
It recently transpired that the cleaned up beach was again full of rubbish. Within three years another 50 items per square metre had washed up. The washed up plastic once again threatens to cause more extreme temperatures of the sand.
Cleaning up does not help unless it done very regularly and the costs are covered.
Photo: Silke Stuckenbrock, beach at Cocos Island.
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