The quantitative and qualitative distribution of phytoplankton was investigated along five NorthSouth transects in the eastern Weddell Sea during the transition from late autumn to winter. Relationships with the regional hydrography, progressing sea ice coverage, nutrient distribution and zooplankton are discussed and compared with data from other seasons. To the north of the Antarctic Slope Front (ASF) a remnant temperature minimum layer was found above the primary pycnocline throughout summer. Surface waters had not entirely acquired typical winter characteristics. While temperature was already in the winter range, this was not the case for salinity. Highest biomass of phytoplankton, with the exception of the first transect, was found in the region adjoining the ASF to the north. Absolute chlorophyll a (Chl a) concentrations dropped from 0.35 to 0.19 lg l À1 . Nutrient pools exhibited a replenishing tendency. Ammonium concentrations were high (0.75-2 lmol l À1 ), indicating extensive heterotrophic activity. The phytoplankton in the ASF region was dominated by nanoflagellates, particularly Phaeocystis spp.. North of the ASF the abundance of diatoms increased, with Fragilariopsis spp., F. cylindrus and Thalassiosira spp. dominating. Community structure varied both due to hydrographical conditions and the advancing ice edge. The phytoplankton assemblage formed during late autumn were very similar to the ones found in early spring. A POC/PON ratio close to Redfield, decreasing POC concentration and a high phaeophytin/ Chl a ratio, as well as a high abundance of mesozooplankton indicated that a strong grazing pressure was exerted on the phytoplankton community. A comparison between primary production (PP) in the water column and the sea ice showed a shift of the major portion of PP into the ice during the period of investigation.

Purpose: This study is a meta-analysis to assess the effect of simulation-based learning using virtual reality (VR) on knowledge, affective, and performance domain outcomes of learning in nursing students. Results:A total of 10 studies (5 randomized control trials (RCTs) and 5 non-RCTs) involved 630 nursing students. As a whole, simulation-based learning using VR appeared to have beneficial effects on the knowledge (I 2 =50%, 95% CI 0.35 [0.09, 0.62], P=0.009), have no significant difference on the performance (I 2 =97%, 95% CI 1.05 [-0.54, 2.63], P=0.19) and have a negative impact on the affective field (I 2 =0%, 95% CI -0.43 [-0.71, -0.15], P=0.003). Conclusion:The existing evidences imply that simulation-based learning using VR might have a positive trend that is beneficial to knowledge and clinical skill acquisition. However, the best way of integration still needs further research to be identified.

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Colonisation of Lake Fletcher, a hypersaline, meromictic lake in the Vestfold Hills, Antarctica, by the calanoid copepod Drepanopus bispinosus, the cyclopoid copepod Oncea curvata and an undescribed cydippid ctenophore is discussed. In 1978, salinity directly under the ice was 66x, and repeated net hauls found no zooplankton. In 1983, adults of D. bispinosus were found, and in 1984, a reproductively active population of this species. Surface water salinity in 1984 was 56x,. During winter 1986, surface salinity was 54& and three zooplankton species (0. bispinosus, 0. cur&a and an undescribed cydippid ctenophore) had established populations in the lake. In 1986/87, high tides caused nearby Taynaya Bay to flood into the lake, and three further species (the calanoid, Paralabidocera antarctica, and two harpacticoids, Harpacticus furcatus and Idomene sp.) were found in the lake. It appears that periodic flooding after 1978 caused a salinity decrease in the lake from 66 to 54x,, and this enabled some invertebrate species to maintain year-round populations, whereas others require marine incursions to re-establish summer only populations.