The occurrence of the copepods Stephos longipes (Calanoida) and Drescheriella glacialis (Harpacticoida) in summer sea ice in the Weddell Sea, Antarctica

• Main Authors: Schiel, Sigrid, Thomas, D. N., Haas, Christian, Dieckmann, Gerhard, Alheit, Ruth
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2001
• Subjects: Antarctic; Antarctic Peninsula; Rotten; The Antarctic; Weddell; Weddell Sea; Antarc*; Antarctic Science; Antarctica; Sea ice; Copepods
• Online Access: https://epic.awi.de/id/eprint/4434/; https://hdl.handle.net/10013/epic.15009

In January to March 1997, a RV Polarstern cruise transected the Weddell Sea resulted in samples being taken in thick pack ice in the southeastern Weddell Sea and then along the marginal ice edge towards the Antarctic Peninsula. Several ice types were thus sampled, over a wide geographic area during late summer/early autumn. During the first 2/3 of the cruise summer conditions prevailed, with air temperatures around 0°C and there was extensive snow melt. A common feature of the ice was the occurrence of surface ponds. Another significant feature during this first warm period was that many floes had quasi-continuous horizontal gaps. The underlying ice was often very porous and rotten. By the onset of cold air temperatures in late February the gaps rapidly started to refreeze, and the gap layer was quickly frozen onto the underside of the overlying ice.The calanoid copepod Stephos longipes occurred in all habitats encountered and showed highest numbers in the surface ice in summer, in the gap water during both seasons and in the refrozen gap water in autumn. Nauplii outnumbered copepodids in the surface ice and refrozen gap water while in the gap water copepodids, mainly stages CI-CIII in summer and CII-CIV in autumn, comprised about 70% of the total population. The harpacticoid species Drescheriella glacialis did not occur in all habitats but was missing in surface ponds and new ice. Nauplii of D. glacialis were rarely found in gap water, but they predominated in the refrozen gaps.Key words: sea ice, copepods, Stephos longipes, Drescheriella glacialis, seasonality