Fish fly, not fry on undersea molten ponds

by Christine Roulston


New flatfish.

It may seem like something from another planet but fish that skip across pools of molten sulphur do exist and have been captured on video in the western Pacific.

The newly discovered flatfish, which thrive around sulphur ponds caused by underwater volcanoes, are the subject of research by University of Victoria ocean scientists Drs. John Dower and Verena Tunnicliffe.

“No one has ever found flatfish in a hydrothermal area and no one expected to see them in such abundance,” says Dower. “In some cases there were a few hundred fish per square metre sitting on the bottom near the sulphur pools.” The team also observed a few fish sitting on the molten sulphur and then moving off unharmed.

The footage was captured during three research voyages, the most recent in May, using remote submersibles along the Mariana Arc, a 1,200 km chain of underwater volcanoes and islands between Guam and Japan. Numerous hydrothermal vents occur in the area, where water becomes hot and mixes with toxic heavy metals.

Dower and Tunnicliffe were part of the expedition sponsored by the National Oceanic and Atmospheric Administration’s (NOAA) Ocean Exploration Program, a scientific and educational outreach program.

The UVic team will describe the fish’s behaviour and their ecology in a forthcoming journal paper.

“We’re hoping to learn more about how they manage to stand the temperatures on these sulphur ponds and also what they eat to support themselves,” says Dower. The researchers believe the flatfish live off small invertebrates in the sediment and “deadfalls” of normal ocean fish that are killed by the volcanic plume and fall to the seafloor.

UVic biology master’s student Jen Tyler will be focusing on how exactly the fish nourish themselves.

In the spring, Dower and Tunnicliffe will travel to New Zealand to study another volcanic arc off the country’s north coast where they believe the same distinctive flatfish resides.

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