The Antarctic Peninsula is warming as rapidly as anywhere on Earth over the past few decades, resulting in ice-shelf collapse, glacial retreat, and rising ocean temperatures. The major goal of this project has been to  evaluate biodiversity and ecosystem function in the unique seafloor animal communities along the Antarctic Peninsula, and then work with in interdisciplinary team to assess the response and sensitivities of Antarctic marine ecosystems to rapid climate change. Project outcomes include important contributions in following areas.

The cold water on the Antarctic shelf has long formed a temperature barrier to cold-intolerant, predacious king crabs, preventing crab dispersal from the warmer deep sea into colder, shallow Antarctic waters. Using an underwater robot called a Remotely Operated Vehicle, we showed that a large, reproductive population of king crabs has crossed the Antarctic shelf into the Palmer Deep in the last 10,000 y. The king crab population (estimated at ~1.6 million individuals) appears to have dramatically altered seafloor biodiversity and ecosystem function in this deep near-shore basin (see pictures 1 and 2). Recent warming trends of shelf waters along the Antarctic Peninsula suggest that, if these king crabs are indeed excluded by cold temperatures, predacious crabs may disperse broadly into shallow Antarctic Peninsula shelf waters within a few decades, potentially causing major diversity loss in the long-isolated, evolutionarily novel Antarctic shelf communities. Our work has stimulated healthy scientific debate on the effects of temperature on Southern Ocean king crabs, and their potential to invade and alter ecosystem structure in Antarctic near-shore waters. Our crab discovery has also elicited extensive press coverage and has highlighted the need to better understand the potential impacts of climate warming on the unique biodiversity of the Antarctic region.

To explore the influence of glacier melting on Antarctic seafloor communities, we conducted the first studies of productivity and biodiversity along transects from the open continental shelf deep into glacier-hosting Antarctic fjords. Unexpectedly, we found that glacier-hosting fjords along the Antarctic Peninsula are extraordinary hotspots of seafloor productivity and biodiversity (see pictures 3, 4, and 5). These Antarctic fjords provide habitat and foraging areas for Antarctic krill and baleen whales, enhance regional seafloor biodiversity, and attract substantial tourist activity along the Antarctic Peninsula. Our studies suggest that productivity/biodiversity hotspots are maintained in these fjords because the fjord glaciers are still in early stages of melting. Our studies also suggest that climate warming may “snuff out” these extraordinary hotspots of Antarctic biodiversity by increasing glacial melt and releasing large amounts of glacial sediments into the fjords.

We have found that the warmer west side of the Antarctic Peninsula harbors much different seafloor communities than the east side, where bottom waters are substantially colder.  In fact, the most abundant sediment dwelling species on the west side of the Peninsula appears to be absent from colder waters on the east side. These results indicate strong, temperature related regional differences in seafloor biodiversity around the Antarctic Peninsula, and suggest that ocean warming by a few degrees might cause dramatic shifts in seafloor communities.  

We have found that seafloor animal communities vary substantially along a transect spanning a large range in time (15 – 170 years) since overlying ice-shelf breakout in the Larsen A Embayment (see picture 6).  We are now analyzing these patterns to help predict how further ice-shelf loss might influence marine ecosystems around Antarctica.

Finally, our project has contributed substantia...

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