US research vessel Marcus Langseth was scheduled to work in Canadian waters. Credit: Lamont–Doherty Earth Observatory

An environmental lawsuit is threatening the departure of a long-planned, US$4.7-million research cruise to image sea-floor structures off the coast of western Canada.

The RV Marcus Langseth, a vessel operated by Columbia University in New York for the US National Science Foundation, had acquired all its permits to depart on 21 August for the Endeavour hydrothermal vents, 250 kilometres southwest of Vancouver Island. But on 10 August, the Canadian activist legal group Ecojustice, in Vancouver, British Columbia, sued the university, the Canadian department of fisheries and oceans and the minister of foreign affairs, alleging among other things that proper procedures were not followed in assessing how the seismic air bursts set off during the cruise would affect marine life.

Cruise co-leader Douglas Toomey, a geophysicist at the University of Oregon in Eugene, says the ship was specifically scheduled and routed to avoid whales, and that marine-mammal observers would be on hand when airguns were fired.

As Nature went to press, a hearing on the lawsuit was being scheduled for this week.

The cruise plans to sink 64 portable seismometers near the Endeavour vent field, fire airguns into the water for 10 days, then retrieve the data-laden seismometers that pop to the surface. Toomey hopes that the analysis will answer important questions about the flow of Earth's mantle, as well as about earthquakes in the region.

Ecojustice officials didn't respond to interview requests, but a statement on its website attributed to group lawyer Lara Tessaro says that the Canadian government should "refuse to sanction the harassment of endangered whales". The lawsuit was filed on behalf of the Living Oceans Society and the Canadian Parks and Wilderness Society, and argues that the minister of foreign affairs should not grant the vessel clearance.

The use of airguns for seismic studies in western Canada has stirred environmental anger before. In 2008, a joint US–Canadian study of granite structures underlying British Columbia was halted (see Nature 451, 3; 2008). Since then, the region has seen growing environmental activism, including a recent sabotage (see Nature doi:10.1038/news.2009.715; 2009) of an onshore explosive charge that was part of a seismic test.