Spatial distribution of copepods in fast ice of eastern Antarctica

The distribution and abundance of sympagic copepods in fast ice of the Australian Antarctic Territory (AAT) were investigated between October and December 1995. Copepods were collected from six sites between the northern Vestfold Hills (Murphy Rocks) and Mawson Station, a distance of approximately 650km. Nine species of copepods were identified from the ice cores, however, of these only three were recorded regularly : Paralabidocera antarctica, Drescheriella glacialis and Stephos longipes. The density of copepods was highest in the bottom few cm of ice, with abundances reaching up to 147l^. The highest concentrations of chlorophyll α were also found in the bottom portion of ice, suggesting that the copepods congregated in regions of high food availability. All developmental stages of Drescheriella glacialis were observed during this study, often from within a single core. In contrast, Paralabidocera antarctica occurred mainly as early copepodite stages, and Stephos longipes mainly as nauplii. These observations were consistent with the documented life cycles for each species. Drescheriella glacialis appears to reproduce and breed within the ice, Paralabidocera antarctica overwinters in the ice but enters a pelagic phase as late-stage copepodids, while nauplii of Stephos longipes are the predominant stages which associate closely with sea ice

Feeding patterns and gonadal maturation of zooplankton in the Indian Sector of the Southern Ocean

第6回極域科学シンポジウム[OB] 極域生物圏11月16日（月）　統計数理研究所 セミナー室1（D305

The Response of Antarctic Sea Ice Algae to Changes in pH and CO2

Ocean acidification substantially alters ocean carbon chemistry and hence pH but the effects on sea ice formation and the CO2 concentration in the enclosed brine channels are unknown. Microbial communities inhabiting sea ice ecosystems currently contribute 10–50% of the annual primary production of polar seas, supporting overwintering zooplankton species, especially Antarctic krill, and seeding spring phytoplankton blooms. Ocean acidification is occurring in all surface waters but the strongest effects will be experienced in polar ecosystems with significant effects on all trophic levels. Brine algae collected from McMurdo Sound (Antarctica) sea ice was incubated in situ under various carbonate chemistry conditions. The carbon chemistry was manipulated with acid, bicarbonate and bases to produce a pCO2 and pH range from 238 to 6066 matm and 7.19 to 8.66, respectively. Elevated pCO2 positively affected the growth rate of the brine algal community, dominated by the unique ice dinoflagellate, Polarella glacialis. Growth rates were significantly reduced when pH dropped below 7.6. However, when the pH was held constant and the pCO2 increased, growth rates of the brine algae increased by more than 20% and showed no decline at pCO2 values more than five times current ambient levels. We suggest that projected increases in seawater pCO2, associated with OA, will not adversely impact brine algal communities

Mid-Holocene Social Interaction in Melanesia: New Evidence from Hammer-Dressed Obsidian Stemmed Tools

The widespread distribution in Papua New Guinea of obsidian stemmed tools dated to the mid-Holocene has led scholars to postulate the existence of large interaction spheres. A newly reported artifact from Biak Island, West Papua provides the stimulus for reconsidering the role of this tool type in regional social interaction. The tool was hammer-dressed, a technique unknown for obsidian flaked tools elsewhere in the world and only rarely applied to obsidian artifacts in Melanesia. This new find closely resembles hammer-dressed obsidian stemmed tools from Garua Island, Papua New Guinea, but these are characterized by LA/ICPMS, PIXE-PGME, and INAA to the local Baki and Kutau-Bao obsidian sources in New Britain, Papua New Guinea, whereas the Biak tool is sourced to outcrops on Lou Island in Manus Province, Papua New Guinea. Hypotheses for functional, symbolic, and social roles of hammer-dressing are explored and evaluated on the basis of replication experiments and use-wear analyses. We argue that the complex and exceptionally rare technologies used for manufacturing hammer-dressed stemmed tools and applied to obsidian acquired from two widely separated obsidian sources substantially add to previous evidence for wide-scale social interaction during the mid-Holocene. The existence of these social networks might also have provided a mechanism for the rapid, extensive spread of innovations like Austronesian languages or Lapita pottery

Zooplankton community structure and dominant copepod population structure on the southern Kerguelen Plateau during summer 2016

The Tenth Symposium on Polar Science/Ordinary sessions: [OB] Polar Biology, Wed. 4 Dec. / 3F Multipurpose conference room, National Institute of Polar Researc