Tag Archives: Mariana deep sea trench

When Life Colonizes Plastic: the Deep Sea Wonder

The ocean deep, where pressure is high, light absent and nutrients scarce, is often seen as a desert. But, as with other deserts, it has oases. Hydrothermal vents, methane-gas seeps and whale corpses are hot spots for marine wildlife.  These natural loci of biodiversity are now being joined by unnatural ones made of plastic. Researchers obtained 33 objects from the deep sea in the South China Sea. Most were bags, bottles and food wrappers, but they picked up some derelict fishing ropes and traps as well…

These objects were teeming with life. When the researchers examined their finds in a laboratory, they found nearly 1,200 individual organisms representing 49 species of crustaceans, corals, echinoderms, flatworms, molluscs, polychaete worms and fungi. They also discovered evidence that some of these species were breeding. There were egg capsules from four different types of snail, and a cocoon from a flatworm known for parasitising crustaceans. This result suggests that accumulations of plastic are, indeed, benthic oases… As to why organisms colonise the objects in these accumulations, the short answer is, “because they are there”.

Excerpts from Marine Ecology: Deep-ocean plastic is a haven for life, Economist, Feb. 6, 2021

Who Owns the Riches of the Melting North Pole

A competition for the North Pole heated up in May 2019, as Canada became the third country to claim—based on extensive scientific data—that it should have sovereignty over a large swath of the Arctic Ocean, including the pole. Canada’s bid, submitted to the United Nations’s Commission on the Limits of the Continental Shelf (CLCS), joins competing claims from Russia and Denmark. Like theirs, it is motivated by the prospect of mineral riches: the large oil reserves believed to lie under the Arctic Ocean, which will become more accessible as the polar ice retreats. And all three claims, along with dozens of similar claims in other oceans, rest on extensive seafloor mapping, which has proved to be a boon to science…

Coastal nations have sovereign rights over an exclusive economic zone (EEZ), extending by definition 200 nautical miles (370 kilometers) out from their coastline. But the 1982 United Nations Convention on the Law of the Sea opened up the possibility of expanding that zone if a country can convince CLCS that its continental shelf extends beyond the EEZ’s limits…..Most of the 84 submissions so far were driven by the prospect of oil and gas, although advances in deep-sea mining technology have added new reasons to apply. Brazil, for example, filed an application in December 2018 that included the Rio Grande Rise, a deep-ocean mountain range 1500 kilometers southeast of Rio De Janeiro that’s covered in cobalt-rich ferromanganese crusts.

The Rio Grande Rise, Brazil

To make a claim, a country has to submit detailed data on the shape of the sea floor and on its sediment, which is thicker on the shelf than in the deep ocean. …CLCS, composed of 21 scientists in fields such as geology and hydrography who are elected by member states, has accepted 24 of the 28 claims it has finished evaluating, some partially or with caveats; in several cases, it has asked for follow-up submissions with more data. Australia was the first country to succeed, adding 2.5 million square kilometers to its territory in 2008. New Zealand gained undersea territory six times larger than its terrestrial area. But CLCS only judges the merit of each individual scientific claim; it has no authority to decide boundaries when claims overlap. To do that, countries have to turn to diplomatic channels once the science is settled.

The three claims on the North Pole revolve around the Lomonosov Ridge, an underwater mountain system that runs from Ellesmere Island in Canada’s Qikiqtaaluk region to the New Siberian Islands of Russia, passing the North Pole. Both countries claim the ridge is geologically connected to their continent, whereas Denmark says it is also tied to Greenland, a Danish territory. As the ridge is thought to be continental crust, the territorial extensions could be extensive)

Lomonosov Ridge, Amerasian Basin

Tensions flared when Russia planted a titanium flag on the sea floor beneath the North Pole in 2007, after CLCS rejected its first claim, saying more data were needed. The Canadian foreign minister at the time likened the move to the land grabs of early European colonizers. Not that the North Pole has any material value: “The oil potential there is zip,” says geologist Henry Dick of the Woods Hole Oceanographic Institution in Massachusetts. “The real fight is over the Amerasian Basin” where large amounts of oil are thought to be locked up…

There’s also a proposal to make the North Pole international, like Antarctica (South Pole), as a sign of peace, says Oran Young, a political scientist at the University of California, Santa Barbara. “It seems a very sensible idea.”

Richard Kemeny, Fight for the Arctic Ocean is a boon for science, June 21, 2019

How Nuclear Explosions Affect the Deep Ocean

Radioactive carbon released into the atmosphere from 20th-century nuclear bomb tests has reached the deepest parts of the ocean, new research finds.  A new study in AGU’s journal Geophysical Research Letters finds the first evidence of radioactive carbon from nuclear bomb tests in muscle tissues of crustaceans that inhabit Earth’s ocean trenches, including the Mariana Trench, home to the deepest spot in the ocean.

Mariana Deep Ocean Trench

Organisms at the ocean surface have incorporated this “bomb carbon” into the molecules that make up their bodies since the late 1950s. Crustaceans in deep ocean trenches are feeding on organic matter from these organisms when it falls to the ocean floor. The results show human pollution can quickly enter the food web and make its way to the deep ocean, according to the study’s authors.


According to researchers, water containing carbon-14 can take centuries to circulate throughout the ocean, but the food web drastically accelerated the process. “There’s a very strong interaction between the surface and the bottom, in terms of biologic systems, and human activities can affect the biosystems even down to 11,000 meters,” said Weidong Sun, a coauthor of the study, “so we need to be careful about our future behaviors.”

AGU Press Release, 8 May 2019