TIME TO GO HOME

NBP08-08 Weekly Science Report – 3 August 2008

"The third and final week of our winter cruise for the FOODBANCS2 Project (in which we are studying the effects of sea-ice loss due to climate change on pelagic-benthic coupling) has been extremely productive and successful. After completing sampling at our fourth primary station (AA, west of Deception Island at 63o 3’S, 61o 36’W) we had a 14 hour transit to Station B, west of Anvers Island (at 64o 48’S, 65o 21’W). There we experienced the first rough weather of the cruise (24 hours of winds at 30-45 knots, and seas of 12-16 feet), but still completed our full station sampling program within 52 hours (6 megacores, 1 box core, 2 otter trawls, 2 tucker trawls, on Blake trawl, two yoyo camera tow, 1 kasten core, one plankton two and one CTD). We also deployed our final time-lapse camera mooring, placing the digital camera on the seafloor at 600 m depths, where is will photograph 3 square meters of seafloor every 12 hours for the next seven months. Because of unexpectedly calm weather (winds below 10 knots for most of the first two weeks on station) and extraordinary hard work from all science, Raytheon and ECO personnel, we were able to complete work at the primary stations along our latitudinal transect (ranging from 63 to 68 S) 36 h early. This allowed us to make a brief visit to Potter Cove on King George Island, and to extend our latitudinal transect to the north, by adding Station N (for “North”) west of Elephant Island at 61 12.0’S, 56 14.6’W. Locating a suitable 600-m deep site for Station N was more difficult than anticipated because the first site we selected, based on mulibeam and Kudsen sonar surveys, was revealed by a camera tow to be paved with cobbles and peppered with boulder-sized drop stones. After additional unsuccessful surveying near King George Island, we located sediment covered continental shelf at 600-m depths 30 miles west of Elephant Island at 61 12.0’S, 56 14.6’W. Neptune allowed is to sample this site for about 16 hours during which we conducted a camera tow, and collected three megacores, 1 box core, 1 Kasten core, a CTD and a Blake trawl. The wind then accelerated to 30-40 knots from the south, bringing high seas and low temperatures (with a wind chill of -35 C), shutting down sampling operations until we had to begin our transit north to Punta Arenas at 0200 h on August 1st. Our transit across the Drake Passage was very smooth, although we hit a bit of rough weather and high head winds (up to 55 knots) along the Atlantic coast of Argentina. We expect to arrive in port in Punta Arenas on time at 0800 h on August 4th.

In summary, our cruise was extraordinarily successful; we have completed our full sampling program from 68 to 63 S along the Antarctic Peninsula, and extended the latitudinal range of our data to Station N at 61 S, providing us with a transect ranging >400 miles from south to north. We conducted a total of 114 field operations (cores, trawls, CTDs, net and camera tows, etc.), averaging 9 operations per day while on station. We also completed 28 core incubations to examine benthic chemical fluxes and labeled phytodetritus uptake by infaunal benthos at all of our primary stations. This remarkable success most be ascribed to excellent weather conditions during most of the cruise, and the remarkable energy, enthusiasm and skill of Raytheon, ECO and scientific personnel.

We thus approach Punta Arenas fatigued but in excellent spirits, having experienced the many faces of the Antarctic Peninsula, from moonlit nights in the sea ice in Marguerite Bay, to gales on the edge of Drake near Elephant Island. We look forward to processing our samples when we get ashore to explore how annual sea-ice duration and climate change along our latitudinal transect influence pelagic-benthic coupling in this remarkable marine ecosystem."

Craig R. Smith, Chief Scientist