Untitled Document

FOODBANCS2 - 2009 Summer Cruise
February 11th - March 17th

BENTHIC FAUNAL FEEDING DYNAMICS ON THE ANTARCTIC SHELF AND THE EFFECTS OF GLOBAL CLIMATE CHANGE ON BENTHO-PELAGIC COUPLING

David J. DeMaster, Craig R. Smith, and Carrie J. Thomas, Principal Investigators

The Antarctic Peninsula region exhibits one of the largest warming trends in the world. Climate warming in this region is reducing the duration of winter sea-ice cover, altering both the pelagic ecosystem and pelagic-benthic coupling. We are conducting a 3-year study along a latitudinal climate gradient on the Antarctic Peninsula to explore the potential impacts of climate change (e.g., reduction in sea-ice duration) on Antarctic shelf ecosystems. We are conducting three cruises during summer and winter regimes along a 5- station transect from Smith Island (62.5°S) to Marguerite Bay (68.5°S), evaluating a broad range of benthic ecological and biogeochemical processes. Specifically, we will examine the feeding strategies of benthic deposit feeders along this climatic gradient to elucidate the potential response of this major trophic group to climatic warming. In addition, we will (1) quantify organic carbon and nitrogen flux, recycling and burial at the seafloor and (2) document changes in megafaunal, macrofaunal, and microbial community structure along this latitudinal gradient. We expect to develop predictive insights into the response of Antarctic shelf ecosystems to some of the effects of climate warming (e.g., a reduction in winter sea-ice duration).

Click on the images for details on our cruise track and to learn more about our temporary home: the Antarctic research vessel Lawrence G. Gould

UH Manoa and NCSU researchers pose for the 'team picture' during the last winter expedition to the Antarctic Peninsula aboard the Antarctic research vessel Nathaniel Palmer. Although it was almost the end of that cruise, there was no reason for sadness or crying because a lot of work and fun would still be waiting for us in the next expedition. Follow us in this next new adventure. Check out our web blog, where we will be posting some interesting and exciting news of this second summer Antarctic journey.

During this 2009 summer cruise, we will recover our high-tech digital, time-lapse cameras attached to aluminum frames (Da Tripods) that have been taking pictures of the seafloor during the past 8 months. The camera is now laying on the bottom of the ocean at a depth of 500 meters and taking photos at a 12-hour intervals. This survey will help us study the feeding activities of roving sea cucumbers and urchins, and explore the possible changes in the seafloor community structure and activity linked to changes in the upper-ocean climate warming.

This sequence of pictures show our research group led by Prof. Smith testing a time-lapse camera on Da Tripod at the Makai Pier on Oahu. The entire equipment package weighs about 250 pounds in air (180 pounds under water). There is a large, specially designed battery (essentially an oil-filled car battery) to power the camera and the strobe for the 8 month period. The system is dropped freely to the seafloor with its own flotation and ballast weight: Two acoustic releases drop the weight on command at the end of the deployment, allow Da Tripod to float back to the surface for recovery (this is called a “free-vehicle system” because it operates independently). Testing the camera under water was essential to calibrate all the settings before the equipment was shipped down to Punta Arenas in Chile, where we departed from for the 2008 winter cruise.

This heavy (1.5 ton) equipment is used to collect marine sediments from the deep-sea bottom. It efficiently brings back to the ship about 100 liters (300 pounds) of mud samples containing worms, crustaceans, brittle stars and all kinds of bacteria. This allow us to study the animal communities living in the sediments We can also use this equipment to study sediment geochemistry evaluating the quantities and reactions of various chemical in the mud.

The sequence of pictures above show the preparation to launch the mooring on which the sediment trap is attached. The mooring consists basically of a heavy anchor at the bottom (an 800 pound railroad wheel!) a line consisting of chain and polyester rope, the sediment trap attached about 150 m above the sea bottom, and a string of floats on top to keep the mooring line verticaland also to float the equipment to the surface at the end of the deployment. Whew! And of course, an acoustic release system is attached to release the anchor at the end of the deployment, and allowing the whole array to float back to the surface of the ocean for recovery. One of the 2009 summer cruise most expected events will be the safe recovery of this valuable gear, bringing important information about Antarctic ocean biogeochemistry.

This funnel-shaped device is used to collect sinking particles from the water column over extended periods of time. All the food reaching the seafloor in our study areas sinks from the sunlit surface waters, and the sediment trap measures how this food material arrives at the seafloor over the year of our study. During the first cruise, we deployed two sediment-trap of moorings (like those shown in the pictures below) at the stations either end of our transect to study latitudinal changes in the abundance and composition of sinking food material to the seabed. The traps rotates a new collection cup into place every two weeks, so we can see how the rate of food sinking to the seafloor changes from summer to winter months.

The images below show a sample of the high-resolution photos taken during the first summer cruise of FOODBANCS2.
The sequence of pictures taken along transects on the seafloor will help us to identify changes in faunal feeding and reproductive patterns linked to the pelagic productivity and loss of sea ice.

The climate is warming in many polar regions, including our study area, but scientists can not yet predict how these remarkably rich ecosystems will change with warming. Sea ice, which provides ice algae as food and help to structure Anarctica ecosystems, is expected to largely disappear in the Antarctic and Arctic. By study how Antarctic food webs, and the diversity and behavior of animals changes from north (little sea ice) to south (lots of sea ice) along the Antarctic Peninsula, we expect to be able to predict how animal communities will change over time at a single location as sea ice disappears. By knowing how warming will change the special communities of animals and other ecosystem processes in Antarctica, we can better predict and manage the effects of human activities, including fishing and tourism in the Antarctic, and our use of fossils fuels to produce greenhouse gases.