Lopes, R. M.. CEM-UFPR, rmlopes@uol.com.br
Dubischar, C. M.. AWI, cdubischar@awi-bremerhaven.de
Bathmann, U. V.. AWI, ubathmann@awi-bremerhaven.de
Pollard, R. SOC, r.pollard@soc.soton.ac.uk

 
DISTRIBUTION OF SMALL COPEPODS AT THE ANTARCTIC POLAR FRONT
 
The Polar Front Zone (PFZ) is characterized by strong physical gradients at about 50 degrees South. Horizontal advection and vertical stratification processes occurring at different time and spatial scales had a major impact on biological rates in this area during the 1995/96 summer (Ant XIII, POLARSTERN). Physical and biological data were recorded continuously to 250 m water depth using a CI Seasoar equipped with an optical plankton counter (OPC). A 100-micrometer mesh sized multinet was used to collect small-sized organisms down to 1000 m. Young copepodites and nauplii of the cyclopoid Oithona similis dominated in the mixed layer, comprising roughly 50-85% of the total mesozooplankton density, and reaching up to 20,000 org.l-1 within the chlorophyll-rich areas. Other small copepods were very abundant above the pycnocline, including Ctenocalanus citer, Microcalanus pygmaeus and Oncaea spp. A typical mesopelagic association occurred below 300 m depth, dominated by O. frigida, several oncaeids and small calanoids. Densities of small copepods were about 3 orders of magnitude higher than those of large dominant calanoids. Accordingly, we suggest that oithonids, oncaeids and small calanoid copepods play a major role in the food web dynamics at the PFZ.
 
Day: Tuesday, Feb. 2
Time: 04:30 - 04:45pm
Location: Hilton of Santa Fe
 
Code: SS23TU0430H