We are conducting an integrated, multi-disciplinary field program to address the rapid and fundamental changes occurring in the Antarctic Peninsula region as a consequence of the abrupt collapse of the Larsen B Ice Shelf in the fall of 2002. A profound transformation in ecosystem structure and function is occurring in coastal waters of the western Weddell Sea. This transformation appears to be yielding a redistribution of energy flow between chemoautotrophic and photosynthetic production, and to be causing the rapid demise of the extraordinary seep ecosystem discovered beneath the ice shelf, providing an ideal opportunity to test fundamental paradigms in ecosystem evolution. We are testing the following hypotheses to elucidate the transformations occurring in marine ecosystems as a consequence of the Larsen B collapse:

1) Cold Seeps: The biogeographic isolation and sub-ice shelf setting of the Larsen B seep has led to novel habitat characteristics, chemoautotrophically dependent taxa and functional adaptations.

2) Background (Non-Seep) Benthos: Benthic communities beneath the former Larsen B ice shelf are fundamentally different from assemblages at similar depths in the Weddell sea-ice zone, and resemble oligotrophic deep-sea communities. Larsen B assemblages are undergoing rapid change.

3) Phytoplankton communities: The previously dark, oligotrophic waters of the Larsen B embayment now support a thriving phototrophic community, with production rates and phytoplankton composition similar to other productive areas of the Weddell Sea.

To test these hypotheses, and to document rapid changes occurring in the Larsen B ecosystem, we are using a remotely operated vehicle, shipboard samplers, and moored sediment traps to:

a) Sample and characterize microbial, macrofaunal and megafaunal components of the seep community,

b) Evaluate patterns of surface productivity, export flux, and mega- and macrofaunal composition in areas previously covered by the ice shelf and compare them to the open sea-ice zone,

c) Place ecosystem changes within the geological, glaciological and climatological context that led to ice-shelf retreat,

d) Predict the likely consequences on marine ecosystems of ice-shelf collapse in other regions of Antarctica vulnerable to climate change.

These activities are being conducted during a cruise in Jan-Mar 2010 to the Larsen B region, with sediment traprecoveries occurring 12 and 24 months later. Our efforts will significantly advance understanding of linkages among the earth’s systems in polar regions and are proposed in the true spirit of IPY. The project is tightly linked to companion projects addressing Marine & Quaternary Geosciences and Cryosphere & Oceans, topics, and to international collaborators from Argentina, Belgium, Canada, Germany, Spain and the United Kingdom.

Follow our scientific expeditions in the Antarctic ocean through our web-blog:
http://uhmanoa-antarctic-research-larissa.blogspot.com/