The genus Pogonophryne is the most species-rich genus of barbeled plunderfishes (Artedidraconidae) and includes more than 25 poorly known species endemic to the Southern Ocean. In this study, we provide new data on the age and reproductive traits of some species of Pogonophryne from the southern Weddell Sea, inferred through otolith reading and histological analyses of gonads. Individual age estimates ranged between 16 and 18 years for Pogonophryne barsukovi and Pogonophryne immaculata and between 10 and 22 years for Pogonophryne scotti. As is commonly found in notothenioids, P. barsukovi followed a group-synchronous type of ovarian development, with pre-vitellogenic and vitellogenic oocytes forming two well-separated egg-size groups. A single spawning female in the sample produced ~1097 eggs and 7.9 eggs g-1. The sample of P. immaculata consisted exclusively of developing males, with testes composed of cysts of spermatogonia, spermatocytes and spermatids. Pogonophryne scotti was the most abundant species, including relatively small males at immature or developing stages of gonad development. Larger females were regressing, being characterized by ovaries with postovulatory follicles and atretic oocytes. Based on the macroscopic and histological analyses of gonads, the spawning season would take place in autumn for P. barsukovi and P. immaculata and in spring–early summer for P. scotti.

Burrow-nesting seabirds constitute an important part of seabird diversity, yet accurate estimates of their abundance are largely lacking, limiting our understanding of their population dynamics and conservation status. We conducted a survey to estimate the number of South Georgia diving petrel (Pelecanoides georgicus) burrows during the 2013–14 breeding season on Ile de la Possession, Crozet archipelago, southern Indian Ocean. We used distance sampling and acoustic playback in order to estimate burrow densities in a priori-selected favourable nesting areas. A total of 855 burrows were detected. The mean altitude of burrows was 601.8 ± 69.4 m. The mean burrow detection distance was 1.77 ± 1.63 m. The burrow density was estimated at 15.649 burrows ha-1 (95% confidence interval (CI): 10.245–23.903) and the slope-corrected total favourable area was 2365.53 ha, which yielded an estimate 37 018 burrows (95% CI: 24 235–56 544). The playback response rate was 15.8 ± 1.3%, and 40.8 ± 1.7% of burrows were occupied or showed signs of occupation. Occupancy rates were low compared to those measured by systematic burrow inspection in other studies. Assuming that laying occurred in 80–93% of the estimated number of burrows, as estimated by previous studies, gives an estimate of 29 614 (95% CI: 19 388–45 235) to 34 426 (95% CI: 22 538–52 585) breeding pairs.

We investigate the spatial distribution, spectral properties and temporal variability of primary producers (e.g. communities of microbial mats and mosses) throughout the Fryxell basin of Taylor Valley, Antarctica, using high-resolution multispectral remote-sensing data. Our results suggest that photosynthetic communities can be readily detected throughout the Fryxell basin based on their unique near-infrared spectral signatures. Observed intra- and inter-annual variability in spectral signatures are consistent with short-term variations in mat distribution, hydration and photosynthetic activity. Spectral unmixing is also implemented in order to estimate mat abundance, with the most densely vegetated regions observed from orbit correlating spatially with some of the most productive regions of the Fryxell basin. Our work establishes remote sensing as a valuable tool in the study of these ecological communities in the McMurdo Dry Valleys and demonstrates how future scientific investigations and the management of specially protected areas could benefit from these tools and techniques.

Many pycnogonids are ectoparasites of benthic invertebrates. Even gastropods are on their menu (reviewed in Dietz et al. 2018). It is somewhat ironic that a marine gastropod, Dickdellia labioflecta (Dell, 1990), might have reversed this principle. Hedgpeth (1964), Sirenko (2000) and Schiaparelli et al. (2008) observed clutches of eggs and young Dickdellia snails on pycnogonids. Sirenko (2000) suggested that this might be a case of ectoparasitism and not just phoresy.

The South Fork of Wright Valley contains one of the largest rock glaciers in the McMurdo Dry Valleys, Antarctica, stretching 7 km from the eastern boundary of the Labyrinth and terminating at Don Juan Pond (DJP). Here, we use results from ground-penetrating radar (GPR), qualitative field observations, soil leaching analyses and X-ray diffraction analyses to investigate rock glacier development. The absence of significant clean ice in GPR data, paired with observations of talus and interstitial ice influx from the valley walls, support rock glacier formation via talus accumulation. A quartz-dominated subsurface composition and discontinuous, well-developed desert pavements suggest initial rock glacier formation occurred before the late Quaternary. Major ion data from soil leaching analyses show higher salt concentrations in the rock glacier and talus samples that are close to hypersaline DJP. These observations suggest that DJP acts as a local salt source to the rock glacier, as well as the surrounding talus slopes that host water track systems that deliver solutes back into the lake, suggesting a local feedback system. Finally, the lack of lacustrine sedimentation on the rock glacier is inconsistent with the advance of a glacially dammed lake into South Fork during the Last Glacial Maximum.

Analysis of multichannel seismic profiles collected on the continental rise off the Sabrina Coast, East Antarctica, has allowed the determination of the acoustic features that are indicative of major evolution steps of the East Antarctic Ice Sheet (EAIS) and highlights the role of meltwater that originated from Totten Glacier in shaping the margin architecture. The arrival of marine-terminating glaciers into the coastal region was recorded by an enhanced sediment input on the continental rise and the nucleation of channel-levees. Downslope sedimentary processes were dominant throughout the Late Cenozoic, testifying to the progressive growth of a highly dynamic, temperate ice sheet on the continent. The last evolutionary step marks the transition to when a full polar glacial regime occurred. The development of a prograding wedge with steeply dipping foresets on the continental shelf and slope exemplifies sedimentation at this time. Other sub-sea-floor observations indicate that downslope fluxes, triggered by glacial meltwater, were still able to deeply erode and deliver sediments to the rise area. This study's findings have led to the identification of expanded and well-preserved sedimentary successions, which we suggest should be considered as priority targets for future International Ocean Discovery Program deep drilling due to the sensitivity of the ice sheet in this area.

Marine-geophysical evidence on sea-floor morphology and shallow acoustic stratigraphy are used to examine the substrate around the location at which Sir Ernest Shackleton's ship Endurance sank in 1915 and on the continental slope-shelf sedimentary system above this site in the western Weddell Sea. Few signs of turbidity-current and mass-wasting activity are found near or upslope of the wreck site, and any such activity was probably linked to full-glacial higher-energy conditions when ice last advanced across the continental shelf. The wreck is well below the maximum depth of iceberg keels and will not have been damaged by ice-keel ploughing. The wreck has probably been draped by only a few centimetres of fine-grained sediment since it sank in 1915. Severe modern sea-ice conditions hamper access to the wreck site. Accessing and investigating the wreck of Endurance in the Weddell Sea therefore represents a significant challenge. An ice-breaking research vessel is required, and even this would not guarantee that the site could be reached. Heavy sea-ice cover at the wreck site, similar to that encountered by Agulhus II during the Weddell Sea Expedition 2019, would also make the launch and recovery of autonomous underwater vehicles and remotely operated vehicles deployed to investigate the Endurance wreck problematic.