Late winter abundance and distribution of phaeodarian radiolarians, other large protozooplankton and copepod nauplii in the Weddell Sea, Antarctica

• Main Authors: Nöthig, Eva-Maria, Gowing, M. M.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 1991
• Subjects: Weddell; Weddell Sea; Antarc*; Antarctica; Sea ice; ice covered waters
• Online Access: https://epic.awi.de/id/eprint/2274/; https://hdl.handle.net/10013/epic.12862

ABSTRACTLarge (>64 µm) protozooplankton (radiolarians, thecate dinoflagellates, foraminiferans, and tintinnid ciliates) and copepod nauplii were sampled at six stations located in sea ice covered waters, using a multinet at five depth intervals between the surface and 1000 m during a late winter expedition of RV 'Polarstern' on a west-east transect across the Weddell Sea. Large (> 400 µm) phaeodarian radiolarians contributed more than 98 % of the carbon in the large protozooplankton fraction; large protozoo-plankton were approximately 38 % of the total protozooplankton carbon during the late winter under the close pack ice in the upper 250 m. Large protozooplankton may therefore be an important food source for small particle-feeding zooplankton in the upper 250m, and a modest food source down to 1000m. Phaeodarian species distributions showed a distinct vertical pattern. Except for spumellarian and nassellarian radiolarians all other protozooplankton (foraminiferans, thecate dinoflagellates, tintinnids) were most abundant in the upper 250 m. The horizontal variation showed a western, central and eastern pattern most probably due to the differing regional hydrography. Feeding ecology of the dominant species of phaeodarians was examined using transmission electron microscopy of contents of feeding vacuoles. The 58 specimens were trophic generalists. The predominance of silica fragments and amorphous material in vacuoles and the similarity of vacuole contents of specimens from 3 depth zones suggest that phaeodarians in late winter may have fed on organic aggregates.