Environment

As Antarctic Sea Ice Melts, Seaweed Smothers Seafloor

As sea ice melts at the poles, increasingly more sunlight hits the seafloor. This allows algae and seaweed to thrive in ecosystems once dominated by invertebrates.

Animals that dwell on the seafloor of the Arctic and Antarctic spend most of their lives in total darkness: Sea ice blocks rays during the spring and early summer, and the sun sets completely in the winter. Late summer and early fall — when the ocean warms up enough to thaw the ice — often marks the only time these creatures see light.

But as climate change causes sea ice to begin melting earlier and earlier in the summer, shallow-water ecosystems will soak up increasingly more rays. New research from a team of Australian biologists suggests this could cause a major shift in the seafloor communities along the coast of Antarctica, where invertebrates like sponges, worms and tunicates — globular organisms that anchor to rocks on the seafloor — currently dominate.