The occurrence of species in both polar regions (bipolarity) is a common phenomenon in the Antarctic flora. Considering the high morphological variation in polar regions due to extreme conditions, the use of molecular tools is indispensable for testing whether Arctic and Antarctic populations indeed belong to the same species. However, few phylogeographic studies of bipolar bryophytes have been conducted so far, especially when comparing molecular and morphological variation. Here, we assess the bipolarity and intraspecific variation of Roaldia revoluta, a strictly bipolar species of pleurocarpous mosses. Phylogenetic analyses based on ITS sequences clearly resolve R. revoluta as monophyletic and confirm its bipolar distribution pattern. Low intraspecific molecular variation in the markers ITS/26S and rpl16 was observed, and most specimens from both polar regions belong to a single haplotype, making it difficult to infer the origin and dispersal routes between both polar regions of R. revoluta. Morphometric analysis furthermore suggests that there are no significant morphological differences among populations from both polar regions and that morphological variation is mainly influenced by local environmental conditions. Our data do not unequivocally support the recent separation of the former intraspecific taxon Hypnum revolutum var. dolomiticum at the species level as Roaldia dolomitica.

The life history and oceanic impact of three very large icebergs that escaped together from the Weddell Sea sea ice, near the tip of the Antarctic Peninsula, are traced from March 2014. Despite the initial proximity of these three icebergs, they followed very different trajectories across the South Atlantic until their eventual break-up and melting 1 year later. The largest, giant iceberg, B17a, spent extensive periods grounded near two different islands. The triplet's gradual melting is examined through the impact on the icebergs' dimensions, but also the meltwater's oceanic influence on the local salinity and primary productivity. It is found that there was generally a significant local surface and mixed-layer freshening of a few tenths of a practical salinity unit, up to several hundred kilometres away from the 10–20 km-sized icebergs. In contrast, the chlorophyll impact was highly temporally variable, although it tended to be larger in the summer. Break-up of these large icebergs did not occur until near the end of their life. We also show that modelling the trajectories of individual very large icebergs can be reasonable for up to 2 weeks if the characteristics of the iceberg and the local ocean and atmospheric forcing are well known.

The concentration of suspended particulate organic carbon (POC) and its carbon isotopic composition (δ13CPOC) were analysed in this study with the aim of exploring the sources and factors influencing levels of POC in the surface water around the Antarctic Peninsula. The scanning electron microscopy results suggest that diatom particles formed the main component of suspended particulate matter, indicating that POC was mainly from in situ primary production. The high concentrations of chlorophyll a and POC in sea water mainly occurred in nearshore and sea-ice edge regions, which might be controlled by nutrient and reactive iron inputs stemming from sea-ice melting. The δ13CPOC in the study area is significantly lower than that in low-latitude waters, with a range of -31.8‰ to -22.8‰ (mean -28.9‰), which was controlled by the high CO2 concentration in the Southern Ocean and might be influenced by phytoplankton growth rates and assemblages. This study helps us to understand material cycling in the Antarctic region under the conditions of global climate change.

Deciphering the sub-ice geology in the Wilkes Subglacial Basin region is important for understanding solid earth-ice sheet evolution and for assessing geological ties between East Antarctica and formerly contiguous Australia. We analyse marine sediment samples derived from drill site U1359 of Integrated Oceanic Drilling Program Expedition 318. Our study reports for the first time that the inland sediment source area comprises a complex mafic igneous terrain and a metamorphosed Precambrian subglacial basement. Pyroxene geochemical analyses confirm the presence of tholeiitic to calc-alkaline basalts. The high-grade part of the subglacial terrain contains upper amphibolite to granulite facies rocks that are comparable to Archaean to Palaeoproterozoic rocks exposed in the Terre Adélie Craton and the formerly adjacent Gawler Craton in Australia. Chemical Th-U-total Pb isochron method (CHIME) ages extracted from a subhedral monazite grain associated with the low-grade biotite-muscovite schist rock fragment provide a unimodal age of 799 ± 13 Ma. Rare occurrences of 800 Ma age in the Terre Adélie Craton and/or George V Coast provide evidence for the presence of at least one late Neoproterozoic magmato-metamorphic event in the interior of Wilkes Land. The affinity of the unexposed geological domains of Wilkes Land, East Antarctica, with their Australian counterparts is discussed in the context of the Rodinia supercontinent.