Deep sea canyons at risk from human activities: New Zealand scientist

New Zealand's extensive underwater canyons are under threat from human activity and need better protection, says a government scientist who worked on an international study of the marine ecosystems.

There were about 10,000 large submarine canyons, major features of continental margins, around the world with at least 230 off New Zealand, according to the study by the International Network for Submarine Canyon Investigation and Scientific Exchange.

Recent studies of canyons had considerably increased understanding of their ecological role, the goods and services they provided to humans, and the impacts of human activities on their overall ecological condition, said marine ecologist Ashley Rowden, of the National Institute of Water and Atmospheric Research, who worked on the study.

Pressures from human activities included litter, fishing, dumping of land-based mine tailings, and oil and gas extraction, Rowden said in a statement Thursday.

The effects of climate change might modify the intensity of currents within canyons, which was predicted to impact the structure and functioning of canyon communities, as well as affect food supply to the deep-ocean ecosystem.

Only 10 percent of canyons worldwide were covered by marine protected areas (MPAs), and these were not evenly distributed around the globe.

Also, canyon protection mainly focused on the shallow areas, and it was important to protect complete systems as they acted as the main connection between shallow and deep waters, said Rowden.

"MPAs within the New Zealand Exclusive Economic Zone protect 41 large canyons, or 17 percent of their total estimated area, but more should be part of the network. They contain important biodiversity and face a number of threats," Rowden said.

The Kaikoura Canyon, one of the most productive deep-sea ecosystems in the world, lying of the northeast of the South Island, was mostly protected.

But the effect of the 7.8-magnitude earthquake in November last year on its deep-sea ecosystem was not yet known, and research was required to understand the impact submarine landslides and sediment-laden currents might have had on its biodiversity.

"We need to know whether the canyon is still operating effectively as a marine reserve," said Rowden. Endit