Tag Archives: arctic seas

Sea sponges survive in the Arctic by feasting on extinct creatures

The bottom of the Arctic Ocean is not the easiest of places to live in. Nutrients and vegetation are very scarce, it’s cold, it’s dark, the elements are pretty much against you. That’s why researchers were very surprised to find a dense population of sponges alive and kicking in the volcanic seamounts of the ocean. As it turns out, they were feeding off fossilized remains of extinct animals and fauna.

Image credit: The researchers.

Researchers from Germany’s Alfred Wegener Institute were around 200 miles from the North Pole on board their research vessel when a submarine camera they were towing caught sight of fuzzy sponges on top of the extinct volcanoes. They just couldn’t believe it. Some of the sponges even stretched over three feet (one meter) across — very big for sponge standards. 

Sponges don’t have a digestive tract, so they rely on passive filter feeding to collect nutrients from water passing through them. Ocean currents in the Arctic Ocean are slow, with not many particles swirling in the water. This made the sighting even more unusual, especially considering tests showed the average sponge was 300 years old. How were they surviving there, for centuries, in what was basically an ocean wasteland?

Studying the sponges

The researchers collected samples of the organisms and the sediment around them and sent the samples to the lab for examination. The analysis showed the seafloor wasn’t as desolate as thought. In fact, the sediment samples were full of fossils. 

The fossils were the empty shells of large deep-sea worms. While they don’t live there anymore, the researchers weren’t surprised to find the shells. Many years ago, gases leaked from the vents of the submerged volcanoes, creating a perfect habitat for the worms. That dynamic ecosystem from a long time ago is still influencing the area. 

The samples collected suggest the sponges are packed with microbial bacteria, with which they form a symbiotic relationship. The bacteria break down the ancient leftovers that then the sponges use to obtain nutrients from. The researchers spotted different sizes of sponges, with the average measuring 30 centimeters or 12 inches.

“This allows them to feed on the remnants of former, now extinct inhabitants of the seamounts, such as the tubes of worms composed of protein and chitin and other trapped detritus,” said first study author Teresa Morganti, a sponge expert from the Max Planck Institute for Marine Microbiology in Bremen, Germany, in a statement.

The researchers believe that there could be more sponge grounds similar to this one along the volcanic ridge of the Arctic Ocean. This would be good news for many other creatures that live there because sponges are natural ecosystem engineers. As they grow, they create places for other animals to live in, depositing a sticky surface for bacteria to settle on. 

A better understanding these ecosystems is essential to protect and manage the diversity of the Arctic Sea, which is currently under serious pressure, the researchers stress. With the sea ice retreating at record rates, the researchers want that the web of life in the Arctic Sea is under pressure. Both the sea ice and its thickness have shown a big decline, affecting the oceanic environment. 

Last year, another group of researchers found sponges below the Antarctic ice shelves while drilling in the Filchner-Ronne Ice Shelf neat the southeastern Weddell Sea. It was an accidental discovery that left the researchers perplexed, calling for further studies (like this one) to better understand what’s actually going on below the Arctic Sea. 

The study was published in the journal Nature

Gulf Stream diagram

Huge methane deposits trapped in seabed sediments might get released due to warmer waters

Gulf Stream diagram

Gulf Stream flow diagram.

Scientists have found hints that methane deposits, tucked away in seabed sediments, have began to breakdown from their frozen state. The shifting of the Gulf Stream from colder to warmer waters is to blame, the researchers note. While a significant greenhouse gas influx into the atmosphere might occur, the researchers conclude, based on their models and experimental data, that it would take thousands of years for the methane to sublimate into gas.

“We know methane hydrates exist here and, if warming continues, it can potentially lead to less stable sediments in this region,” says Matthew Hornbach, a marine geologist at the Southern Methodist University in Dallas, Texas, who led the study.

The study suggests some 2.5 gigatonnes of methane hydrate along the continental slope of the eastern United States are currently subjected to destabilizing. Temperature alone isn’t enough to cause their release, however underwater land slides can trigger such an event, and the region is particularly prone to them.

While it’s yet unclear what impact such a quantity of methane released in the atmosphere might have on global warming, one thing certain is that such an event is far from happening in the near future. The scientists used seismic data collected in 1977 to model where they expected the frozen methane to become gaseous in the western North Atlantic margin. After correcting interference in their model to better reflect reality, the scientists found that water was much cooler in the area before.

After modeling heat flow through the methane hydrate sediments in relation to time at the current temperature, the authors found that it would take some 5,000 years for all the methane to sublimate and become gas.  “We don’t know where we are in the 5,000-year time frame, but our best approximation suggests we are 800 to 1,000 years in,” says Phrampus.

While the study offers relief by presenting the slim chances of such an event occurring in the near future, it does highlight the potential danger that the destabilization of greenhouse gas deposits poses. There are many hydrate deposits around the world that deserve attention, like the ones located in the Arctic seabed. The region’s waters have warmed significantly in the past decades, and since it’s the place undergoing the maximum amount of change, it’s therefore the best place to study these dynamics. Also, whether destabilized hydrates can make the continental slopes more unstable is a discussion still far from reaching a widely approved conclusion.

“The embarrassing reality is we don’t have any solid confirmation that these connections are causative rather than correlative,” says Charles Paull, a marine geologist at Monterey Bay Aquarium Research Institute in Moss Landing, California, who has studied this western Atlantic region in detail.

Findings were reported in the journal Nature.

Mysterious creatures found in Antarctica seas

misterious creatures

The return of three Antarctic marine science research vessels marks the crowning of one of Australia’s most ambitious International Polar Year projects, a census of life in the Antarctic seas. The ships (Aurora Australis and collaborating vessels L’Astrolabe from France and Umitaka Maru from Japan) came back from the Southern Ocean, their decks overflowing with a vast array of ocean life.

These samples of ocean life are just fascianting, with most of them never even seen before; these unknown species delighted scientists. Aurora Australis voyage leader Dr Martin Riddle says that their expedition uncovered a remarkably rich, colourful and complex range of marine life in this extreme environment which has been previously undiscovered.

“Some of the video footage we have collected is really stunning – it’s amazing to be able to navigate undersea mountains and valleys and actually see what the animals look like in their undisturbed state,” he said.

“In some places every inch of the sea floor is covered in life. In other places we can see deep scars and gouges where icebergs scour the sea floor as they pass by. Gigantism is very common in Antarctic waters – we have collected huge worms, giant crustaceans and sea spiders the size of dinner plates.

We haven’t discovered the extreme environments from our planet yet, and these explorations are more than welcome. Still, could the much talked about nuclear waste dumped in Antarctica have something to do with these species? Nobody seems to even mention this, so it’s probably not the case.

“Specimens collected will be sent to universities and museums around the world for identification, tissue sampling and bar-coding of their DNA. Not all of the creatures that we found could be identified and it is very likely that some new species will be recorded as a result of these voyages.”