As climate change renders more of the Arctic free of ice for more of the year, shippers that increasingly move cargo north of Canada and Russia are potentially also transporting unintended cargos of organisms from lower latitudes. In a new study, researchers have detected a host of more southerly species in the ballast waters of ships at an Artic port and have determined that by midcentury, at least one of the most pernicious of those interlopers could spread to the Far North.
Past studies have examined the risk of invasive species infesting Arctic regions by modeling shipping routes and expected changes in ocean climates. The research team led by Chris Ware of the Tromsø University Museum has taken the novel step of analyzing ballast water of Arctic-bound ships. Ware and his colleagues took samples in 2011 from eight ships arriving in Svalbard, a group of Norwegian islands in the Arctic waters off Scandinavia. Of the 73 zooplankton species they found living in the ballast water, 23 hailed from outside the area, including larvae of several barnacle and crab species.
Not all nonnative species invade new habitats when they encounter them. “One of the biggest challenges in researching biological invasions is predicting what species might cause impacts if they are introduced to new locations and what those impacts might be,” Ware explained via email. However, one of the species that turned up in this study has already earned a nasty reputation: Carcinus maenas, the green crab, ranks among the world’s 100 worst invasive alien species called out in the Global Invasive Species Database and has already damaged ecosystems in Australia and the Americas.
Today’s still harsh conditions in Svalbard prevent the green crab and other potential invaders from getting a foothold there, but Ware’s team mapped the likely extent of future hospitable conditions for the species they found, using the projections of an emissions scenario that assumes greenhouse gases will continue to rise for the next century. Within 40 years, climate change will likely alter Svalbard’s habitat enough to make it hospitable to many of the foreign crabs, barnacles, shrimp, and other species currently arriving in ballast water, and the same will hold true across the Arctic.
Ware and his colleagues published their findings last month in the Journal of Applied Ecology. They used a high-end emissions scenario, they reported in the paper, because it best approximates the actual emissions trajectory of the past decade. Because emissions might rise less steeply or even decline in the future, the team described its findings as “an assessment of the sensitivity of the biophysical system, rather than a prediction.”
With warming of the Arctic, “invasive marine species, including those transported through ballast water, represent a significant problem for the Arctic,” according to Martin Sommerkorn, an ecologist who is the director of the World Wide Fund for Nature’s Global Arctic Programme. The Arctic passages opened by climate change will also make east–west movement between oceans easier for marine organisms, he suggested, potentially destabilizing ecosystems further.
—Rebecca Heisman, Freelance Science Journalist; email: [email protected]
Citation: Heisman, R. (2015), Ships bring more than cargo to Arctic waters, Eos, 96, doi:10.1029/2015EO041175. Published on 9 December 2015.