State of the Oceans — Log 93
YOUR WEEKLY BRIEFING FROM PARLEY
This image: Jason Washington / Coral Reef Image Bank. Header image: Rick Miskiv.
PLASTIC POLLUTION
Until now, scientists believed that microplastics were mainly formed by slow, physical processes like sunlight and waves, that slowly break apart plastic over time. But this week, a new study suggests that animals also play a “completely unexpected” role in breaking down marine debris into microplastics.
In an experiment at University College Cork in Ireland, tiny crustaceans fragmented plastic into pieces smaller than a cell – in just four days. This rapid plastic breakdown (which the researchers call “biological fragmentation”) may also affect feeding: 66% of plastic the crustaceans ate was plastic they had fragmented.
The species from this experiment is a member of the genus Gammarus, which has over 200 species and is common across the globe. That means similar crustaceans all over the world could quickly be spreading microplastics that are small enough to pass through cell walls and harm wildlife: “This definitely adds an extra layer to our understanding of plastics’ fate in our environment,” said the study’s lead author. “Once plastics reach rivers and oceans, we don’t really know what happens to them. If animals are ingesting and fragmenting them, the problem is amplified.”
SHARKS AND FISH
Two devastating stories this week: First, a new report finds that sharks are ‘functionally extinct’ across a fifth of all coral reefs. Like stewards, sharks keep fish populations in check and healthy, but their numbers are so low they can no longer regulate reefs all over the world. Next, another study shows that migratory river fish populations have dropped by 76% since 1970. Pollution, overfishing, the climate crisis… the global die-off has many causes, but removing dams can make a difference. “Almost without exception, where dams have been removed, you see populations bounce back, often much more quickly than anticipated,” said one of the study’s authors. Migratory fish carry nutrients from the ocean into fresh waters, and they support the livelihoods of millions. As another researcher warned, “If these fish populations continue to decline, there will be far-reaching consequences for many species which rely on them.”
ILLEGAL FISHING
An industrial-sized Chinese fishing fleet is parked just outside of the Galápogos Islands marine reserve, threatening wildlife and conservation efforts within the archipelago. Every year, Chinese vessels fish along the boundaries of this UNESCO World Heritage Site, but this year’s fleet is among most dangerous yet: “The fleet’s size and aggressiveness against marine species is a big threat to the balance of species in the Galápagos,” said one of Ecuador’s former environment ministers. The Ecuadorian navy is on high alert as a Chinese vessel has been caught fishing illegally inside the marine reserve before. In 2017, the Fu Yuan Yu Leng 999 was apprehended with 300 tons of marine life aboard. This story comes just one week Parley collaborator Ian Urbina announced the discovery of the world’s largest illegal fishing fleet: 800 Chinese ships were found fishing North Korean waters in violation of U.N. sanctions.
INNOVATION
For a new study, unmanned underwater gliders covered thousands of miles listening for ‘clicks’ from the endangered Mediterranean sperm whale. This novel approach shed light on the species’ daily routine, including its foraging behavior and the fact that these whales are not exactly ‘morning people’. From reducing bycatch to re-routing shipping lanes, the authors believe their work could promote the conservation of the 2500 remaining Mediterranean sperm whales and marine mammals everywhere. In the words of one co-author, “Gliders allow us to go into new areas, which we wouldn’t have observations from otherwise, and also at times of year when we are not usually monitoring.”
OCEAN WONDERS
A team of researchers have discovered a new current flowing into the Faroe Bank Channel, which is one of the world’s largest deep sea “waterfalls.” The Nordic Sea is a relatively well-documented region, so this finding comes as a surprise. This current also adds to our understanding of ocean circulation and potentially the climate crisis. Across the North Atlantic, ocean currents naturally regulate Earth’s glacial cycles. This new one could be an important piece of the puzzle. As one author put it, “The two discoveries reported here, in one of the best studied areas of the world ocean, is a stark reminder that we still have much to learn. This is crucial given the absolutely fundamental role [currents] play in the major glacial-interglacial climate swings.”
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