Antarctic icebergs decimating seafloor life

A decade ago, the sea floor off the coast of the west Antarctic Peninsula (WAP) was a patchwork quilt of different colors and species. But now, icebergs are increasingly scouring the sea floor as they drift close to shore, fundamentally altering that rich ecosystem in the process. That’s the conclusion of a study reported this week in Current Biology. Each winter, the WAP sea surface freezes over, forming a skin of “fast ice” that holds back the bergs. But with climate change, the WAP is experiencing rapid regional warming, with fewer days each year of fast ice—letting the icebergs into the shallows more often, where they carve huge gashes through the habitat of the colorful, tentacled invertebrate animals carpeting the sea floor. The team examined the spatial distribution, diversity, and interactions between and within species from 1997 to 2013, along with scours from the ice each year. What it found was sobering: Most species weren’t able to recover from the increasingly frequent pounding by the ice. Instead, one species—a nondescript white mosslike animal encrusted on the rocks—emerged as an all-conquering winner, edging out the rest by its sheer ability to take a beating. It now has a near-monopoly in the area, the study found—and that could make the whole region more vulnerable to invading species.

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