Ecophysiology of Antarctic sea-ice meiofauna

摘要: Sea ice is permeated by small brine channels, which are characterised sub-zero temperatures and varying salinities. Despite sometimes extreme conditions a relatively diverse fauna flora thrives within these channels. Stephos longipes, Paralabidocera antarctica Drescheriella glacialis the dominant copepod species found Antarctic sea ice. Their life-cycle strategies well-established, but life cycles of other meiofauna (metazoans > 50 µm) little explored. Adaptation mechanisms allowing to survive largely unknown. In order increase our knowledge sea-ice meiofauna, different microhabitats their metazoan were studied during two cruises with R/V “Polarstern” western Weddell Sea. The sympagic in sub-ice layer was Ectinosoma sp., occurring regularly D. glacialis/racovitzai, Diarthrodes cf. lilacinus, Idomene S. longipes. glacialis/racovitzai longipes members surface-layer late spring. populations consisted mainly adults early naupliar stages this layer, points an active reproduction surface layer. Other taxa undetermined turbellarians, gastropod Tergipes antarcticus, ctenophore amphipod species. Sampling records from Bellingshausen Sea, as well Prydz Lutzow-Holm Bay indicate that T. antarcticus widely distributed During study, adults, juveniles, veliger larvae egg clutches A thorough morphological anatomical description all performed developmental time determined being 31 days (range: 13 65 days) at 0 °C. observed racovitzai, habitat allows assign also true meiofauna. changing salinities formation for P. antarctica, antarcticus. haemolymph isosmotic medium 25 45 g/kg (S. longipes) 55 (P. antarctica). Thermal hysteresis (a non-colligative inhibition growth) not antarctica. These first reports thermal gastropods crustaceans, respectively. acquisition seems enable exploit available particular, high abundances stronger temperature fluctuations can occur than lowermost centimetres be restricted physiologically lower importance choice remains shown. probably prerequisite ability spawn Adaptations low elevated salinties on transcriptional level investigated Two isoforms protein found, which, if recombinantly expressed, confers hysteresis. homology group (putative) antifreeze proteins bacterium, snow mold several diatoms and, contrast, no homologs any lineage suggest obtained through horizontal gene transfer. This key event evolution