Hotspot volcanoes

The ‘lost world’ of underwater volcanoes is a hotspot for humpback whales

A recently discovered ‘lost world’ of underwater volcanoes teems with diverse marine life above and below the waves.

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

Although these water mountains reach a height of up to 3000m from the surrounding seabed, they are still far below the ocean, with the highest peaks starting at a depth of almost 2000m.

Eric Woehler/CSIRO

“Our multibeam mapping has revealed for the first time in vivid detail a chain of volcanic seamounts rising from an abyssal plain to around 5000m depth,” said Dr Tara Martin of the mapping team. in a press release.

“Seamounts vary in size and shape, with some having sharp peaks while others have wide flat plateaus, dotted with small conical hills believed to have been formed by ancient volcanic activity. Have detailed maps of these areas is important to help us better manage and protect these unique marine environments and provides a springboard 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.

“While we were over the seamount chain the ship was visited by large numbers of humpback and longfinned pilot whales,” said Dr Eric Woehler of 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 one day, followed by a group of 60-80 long-finned pilot whales the next day. We also saw a large number of seabirds in the area, including four species of albatrosses and four species of petrels.

“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 migrating animals like whales could use these underwater features as vital stopping points, to refuel during their journey, and to serve as aids to navigation.

“These seamounts may serve as an important signpost on an underwater migratory highway for humpback whales that we have seen move from their winter breeding to their summer feeding grounds,” Dr Woehler said.

“Fortunately for us and our research, we parked just above this marine life highway!”

The life and origin of these seamounts will be investigated later this year when Investigator returns to the area for two more research trips departing in November and December.