Undersea habitats supporting rare and potentially valuable organisms are at risk from seafloor mining scheduled to begin within this decade, according to a new study by a University of Toronto Mississauga geologist.
According to Jochen Halfar, assistant professor of earth sciences at the U of T Mississauga, and lead author of the study, mining of massive sulphide deposits near undersea hydrothermal vent systems could smother and contaminate the fragile flora and flora these vents support.
'Black smokers', or the undersea hydrothermal vents, as they are called, occur in areas where new oceanic crust is formed through undersea volcanic activity. Some biologists argue they represent the origins of life on earth.
Spewing 350-degree Celsius water into the frigid deep-sea environment, they support sulphur-loving bacteria and bizarre worm and clam species. As such, mining and other activities could irreversibly damage this fragile ecosystem.
'We need to act now to establish scientific and legal methods to protect these sensitive ecosystems and minimize the potential environmental impact of this industry. Imposing regulations after operations begin would prove very difficult, and some of the governments in the jurisdictions targeted by this industry have a poor record of mining oversight. The prospects for regulation of underwater mining are not good,' said Prof. Halfar.
A Canadian-based company is currently planning the world's first commercial undersea exploration for high-grade gold and copper, targeting an area known as the Manus backarc basin off the coast of Papua New Guinea.
'The demand for metals is growing rapidly, and along with the sharp rise in metal prices, we have seen the depletion of metal-rich terrestrial mines. For mining companies and their investors, undersea mining offers high concentrations of ore at relatively low production costs,' said Prof. Halfar.
'The mining operations will use a strip-mining approach to remove deposits within the top 20 metres of the seafloor, using remotely operated underwater mine cutters and a hydraulic pump system to transfer roughly two million tons of ore per year to the surface. These strips would be located approximately 500 meters to two kilometres from the active vents, but the cutting and pumping process will disgorge considerable amounts of fine sediment into the water column—a serious problem for vent organisms that feed by filtering the water in their habitat,' he said.
But the process would also raise the concentrated nutrients from the deep sea to the relatively nutrient-poor surface waters of the ocean, causing algal blooms and potentially contaminating waters that support Papua New Guinea's commercial fishing industry, as well as local subsistence fishers, he added.
'Depending on ocean currents, these nutrients could drift widely, disrupting the food chain and potentially damaging ecosystems that lie within other countries' economic zones or in international waters. This poses additional problems, because while a state has the right to exploit its own resources, international environmental law decrees that it cannot damage the environment beyond its boundaries,' said Prof. Halfar.
The study appears in the May 18 issue of the journal Science, and is co-authored by Rodney Fujita, a marine ecologist with Environmental Defense.