Science

'Lost World' Of Underwater Volcanoes Is A Hotspot For Humpback Whales

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A newly-discovered “lost world” of underwater volcanoes is teeming with diverse marine life above and below the waves.

Scientists aboard the Commonwealth Scientific and Industrial Research Organisation (CSIRO) vessel Investigator mapping the seafloor have uncovered a diverse chain of volcanic seamounts located in deep water about 400km east of Tasmania.

Although these aquatic mountains reach height of up to 3000m from the surrounding seafloor, they’re still far beneath the ocean, with the highest peaks starting at a depth of nearly 2000m.

Humpback whales seen from the deck of the Investigator research vessel over a newly-discovered range of underwater volcanoes (Credit: Eric Woehler/CSIRO)Eric Woehler/CSIRO

“Our multibeam mapping has revealed in vibrant detail, for the first time, a chain of volcanic seamounts rising up from an abyssal plain about 5000m deep,” Dr Tara Martin of the mapping team said in a statement.

“The seamounts vary in size and shape, with some having sharp peaks while others have wide flat plateaus, dotted with small conical hills that would have been formed by ancient volcanic activity. Having detailed maps of such areas is important to help us better manage and protect these unique marine environments, and provides a stepping stone for future research.

Underwater volcanoes like these are usually key sites for marine wildlife and the ship’s explorations showed increased phytoplankton activity in the area. The researchers were also treated to frequent sightings of life above water as well.

“While we were over the chain of seamounts, the ship was visited by large numbers of humpback and long-finned pilot whales,” Dr Eric Woehler from BirdLife Tasmania, who was on Investigator with a team conducting seabird and marine mammal surveys, said.

“We estimated that at least 28 individual humpback whales visited us on one day, followed by a pod of 60-80 long-finned pilot whales the next. We also saw large numbers of seabirds in the area including four species of albatross and four species of petrel.”

“Clearly, these seamounts are a biological hotspot that supports life, both directly on them, as well as in the ocean above,” he added.

Research indicates that migratory animals like whales might use these underwater features as vital stopping points, to fuel up on their journey and to serve as navigational aids.

“These seamounts may act as an important signpost on an underwater migratory highway for the humpback whales we saw moving from their winter breeding to summer feeding grounds,” Dr Woehler said.

“Lucky for us and our research, we parked right on top of this highway of marine life!”

The life and origin of these seamounts will be further studied later this year when Investigator returns to the region for two further research voyages departing in November and December.

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