First Cruise of Trophic BATS Project
Alexandra Freibott, Stephanie Wilson and Susanne Neuer participated in Atlantic Explorer cruise X1101 from February 22 till March 6, 2011 to study the trophic interactions and particle export during the winter season in the Sargasso Sea, dubbed “Trophic BATS”. This was the first in a series of four cruises within this recently funded NSF project in which Neuer is a principal investigator. Other members of the team are Dr. Tammi Richardson (lead PI and chief scientist of the cruise) from the University of South Carolina, Dr. Mike Lomas from the Bermuda Institute of Ocean Sciences and Dr. Rob Condon from the Dauphin Island Sea Lab in Alabama.
At a total of five sites (an anticyclonic eddy, slope waters of the eddy, and repeatedly the Bermuda Atlantic Time Series study site, BATS), the researchers studied phytoplankton production, microzooplankton grazing, mesozooplankton grazing and particle export. A novel deployment array was used for the production and microzooplankton grazing experiments, so called ‘sundials’, disks on which the incubation bottles are attached so they would all receive the same light intensity. With these sun dials attached to a line at different depths in the upper 100 m (the euphotic zone), the water in the bottles can be incubated at the same depth from where the sea water was originally sampled. These incubations made for some early mornings (or short nights); we obtained the water at about 2 AM with a very early rosette cast, set up the experiments and deployed again right before dawn. Stormy winter weather forced us to deploy the last incubation experiment on deck in incubators as 12 ft waves make work on the fantail too difficult.
Exciting observations in the zooplankton which the Condon group collected by nets were the salps, and lots of them. The almost entirely transparent animals (about half to two inches long) belong to the ‘jelly plankton’ but taxonomically they are tunicates, primitive chordates (very distant relatives of the vertebrates). They filter through intricate mucus filters the tiniest of phytoplankton; they are truly vacuum cleaners of the ocean. Because of the production of large fast sinking fecal pellets they have a special role in the particle flux of the ocean. Stephanie Wilson of the Neuer group kept them in large beakers and collected their fecal pellets which she will analyze by DNA based molecular tools to identify the prey spectrum of the salps.