Antarctic Species Disappear as Icebergs Released by Global Warming Roam Free

It turns out that warming temperatures are impacting more than just the ice in Antarctica. As icebergs are turned free to roam most of the year, boulders that were once encrusted with a thick assemblage of species are now only supporting a single species. The findings reveal the impact on biodiversity when it comes to climate change.

"The Antarctic Peninsula can be considered an early warning system-like a canary in a coal mine," said David Barnes, one of the researchers, in a news release. "Physical changes there are amongst the most extreme and the biology considered quite sensitive, so it was always likely to be a good place to observe impacts of climate change-but impacts elsewhere are likely to be not too far behind. A lot of the planet depends on the near-shore environment, not least for food; what happens there to make it less stable is important."

Fenstrulina rugula is a suspension feeder that belongs to a group that's sometimes referred to as moss animals. In previous studies, scientists had noted that there was an increase in mortality of this pioneer species. Yet the researchers in this study wanted to see how widespread that mortality was; after a survey dive in 2013, the researchers found a spot where no live animals could be found.

Startled by this, the researchers decided to conduct further surveys. They detailed the first assemblage-level changes coincident with increased scouring-the process by which icebergs impact boulders. No species present in 1997 has disappeared. However, many have become so rare that they play little role in the ecological community. In 2013, in fact, about 96 percent of all interactions involved just one species.

"Warming is likely to increase ice scour mortality and reduce assemblage complexity and could aid establishment of nonindigenous species," write the researchers in their paper, according to a news release. "We expect the deeper seabed to become richer in benthic colonization with more ice shelf collapse and fast ice losses, but hard surfaces in the shallows are likely to become deserts dominated by rapidly colonizing pioneers and responsive scavengers-with little role for spatial competition or even predation in shaping the structure of such assemblages."

The findings are published in the journal Current Biology.