A year round comparative study on the population structures of pelagic Ostracoda in Admiralty Bay (Southern Ocean)

• Published in: Hydrobiologia
• Main Authors: Blachowiak-Samolyk, K., Angel, M.V.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2007
• Subjects: Halocyprida; Ostracoda; Antarctic; Southern Ocean; Antarctic Peninsula; King George Island; Bransfield Strait; Admiralty Bay; Croker; Croker Passage; Antarc*
• Online Access: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=210964

The population structures of the three dominant planktonic halocyprid Ostracoda species in Admiralty Bay (King George Island, Antarctic Peninsula) were followed throughout the course of a year in zooplankton samples collected once every three weeks from February 1993 to January 1994. The sampling was conducted at two stations: A in the central part of Admiralty Bay (400-0 m) and B in the entrance to the Bay from the Bransfield Strait (400-0 m). The samples were taken using a WP-2 net (square mouth opening of 0.196 m 2 and 200 µm mesh) hauled vertically from the bottom to the surface. Changes in the age structures of the populations of three species Alacia belgicae , Alacia hettacra and Metaconchoecia isocheira were tracked. Their population structures differed. The changes in A. belgicae suggested that it reproduces year-round, whereas both A. hettacra and M. isocheira probably complete their life cycles within a year. The cycle in A. hettacra probably starts earlier in the year than that of M. isocheira . Populations of A. belgicae and M. isocheira were more advanced in their development at station A, than at station B, but A. hettacra was more advanced at the latter. Advection appears to play a role in maintaining the populations in the shelf waters. Comparisons between populations in the shelf area (Admiralty Bay) and in open ocean waters (Croker Passage) show that the M. isocheira population is older in shelf water whereas the age structure of A. belgicae population is not influenced by the locality.