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Climate-driven changes in disturbance are a major threat to ecosystem Functional diversity. The selective mechanisms underlying ecosystem response to disturbance are far from universal and remain the subject of scientific debate. Ice scouring of the shallow Antarctic benthos is one of the largest disturbance gradients in the natural environment and thus provides an opportunity to investigate how disturbance gradients influence functional structure of a biological assemblage. The Western Antarctic Peninsula, in particular, is a hotspot of climate-driven environmental change. Addressing how this system might respond to species loss is critical. Previous surveys across the shallowest 100 m of the seabed, detected unimodal changes in diversity and a shift in assemblage composition in response to disturbance gradients. This study investigated how functional traits and associated functional diversity change across the depth gradient. Our results revealed that selective mechanisms, such as disturbance filtering and inter-species competition, reduce functional redundancy at the extremes of the disturbance gradient. Our study highlights areas of potential vulnerability to future environmental change due to low functional redundancy. Threatening the important negative (mitigating) feedbacks on climate change, through blue carbon, currently provided by Antarctic continental shelf benthic assemblages.

Marine heatwaves (MHWs) are increasing in both intensity and frequency against a backdrop of gradual warming associated with climate change. In the context of MHWs, animals are likely to experience sub-lethal, rather than lethal effects, defining long-term limits to survival and/or impacting individual and population fitness. This study investigated how functional sub-lethal limits track critical thresholds and how this relationship changes with warming rate. To this end we monitored basic functioning, specifically the ability to right, feed and assimilate energy, as well as oxygen consumption rate in the common Antarctic sea urchin, Sterechinus neumayeri. Water temperature in experimental systems was increased at rates of 1oC day-1, 0.5oC day-1 and 0.3oC day-1, in line with the characteristics of MHW events previously experienced at the site where the study urchins were collected on the Antarctica Peninsula. Functioning was assessed during the simulation of MHWs and sub-lethal limits determined when the rate of functional degradation changed as temperature increased. Results suggest that thermal sensitivity varies between the key biological functions measured, with the ability to right having the highest thermal threshold. Arguably, the most interesting result was that functions deteriorated at lower temperatures when warming was more rapid (1oC day-1), contrary to lethal critical thresholds, which were reached at lower temperatures when warming was slower (0.3oC day-1). MHWs and their impacts extend far beyond Antarctica and in this context, our analyses indicate that the onset rate of MHWs is critical in determining an organism’s ability to tolerate short-term elevated temperatures.

Embryonic development is dictated by tight regulation of DNA replication, cell division and differentiation. Mutations in DNA repair and replication genes disrupt this equilibrium, giving rise to neurodevelopmental disease characterized by microcephaly, short stature and chromosomal breakage. Here, we identify biallelic variants in two components of the RAD18-SLF1/2-SMC5/6 genome stability pathway, SLF2 and SMC5, in 11 patients with microcephaly, short stature, cardiac abnormalities and anemia. Patient-derived cells exhibit a unique chromosomal instability phenotype consisting of segmented and dicentric chromosomes with mosaic variegated hyperploidy. To signify the importance of these segmented chromosomes, we have named this disorder Atelís (meaning - incomplete) Syndrome. Analysis of Atelís Syndrome cells reveals elevated levels of replication stress, partly due to a reduced ability to replicate through G-quadruplex DNA structures, and also loss of sister chromatid cohesion. Together, these data strengthen the functional link between SLF2 and the SMC5/6 complex, highlighting a distinct role for this pathway in maintaining genome stability.

Decommissioning of oil and gas infrastructure globally has focused attention on its importance as hard substratum on continental shelf and slope habitats. Observational studies are needed to improve understanding of faunal assemblages supported by offshore infrastructure and better predict the effect of removal. Here, we present results from visual inspection and physical sampling of a small oil and gas industry structure decommissioned from an oil field in the North East Atlantic. This is supported by observations of similar structures nearby and by photographs of the surrounding seabed from environmental baseline surveys. The structure supported a reasonably high biomass and diversity of invertebrates (>10 kg and >39 macrofaunal and 17 megafaunal species) and fishes (>20 kg biomass and >4 species). The invertebrate megafaunal species present on the structure were a sub-set of the hard substratum fauna observed on surrounding seabed. Porifera were absent from the structure. Biological succession in the first 2 years occurred as follows. Sparse colonies of the hydroid Obelia sp. stet were early colonisers then subsequent development of thick hydroid turf (Obelia sp. stet. and Halecium sp. stet.) supported an invertebrate assemblage (2654 individuals kg wet mass–1) dominated by saddle oysters [Pododesmus squama (Gmelin, 1791) and Heteranomia sp. stet.)] and scale worms (Harmothoe spp.). Percentage cover of hydroid turf varied significantly over the structure, with most growth on sections exposed to strongest currents. Commercially important fish species present around the structure included Gadus morhua (Atlantic cod), Pollachius virens (saithe) and Lophius piscatorius (monkfish). Studies of artificial structures such as this provide much needed data to understand their role in the ecology of seafloor habitats and inform environmental decision making on all stages of industry from exploration to decommissioning. We show that the ecological role of the decommissioned

The accepted paradigm for reproduction in Antarctic marine species is one where oogenesis takes 18 months to 2 years, and a bimodal egg-size distribution where two cohorts of eggs are present in female gonads throughout the year. These slow gametogenic traits are driven by low temperature and/or the restriction of resource availability because of extreme seasonality in the marine environment. Here we present data on the reproductive ecology of the common Antarctic bivalve Aequiyoldia eightsii (Jay, 1839) (Protobranchia: Sarepidae) from monthly samples collected between January 2013 and May 2014 at Hangar Cove, Rothera Point on the West Antarctic Peninsula. These data show that A. eightsii is unusual because it does not follow the typical pattern expected for reproduction in Antarctic marine invertebrates, and differs also from closely related nuculanid protobranch bivalves with respect to gametogenic duration and reproductive periodicity. Continuous oogenesis, evidenced by the year-round occurrence of previtellogenic, vitellogenic, and ripe oocytes in female gonads, is supplemented by a seasonal increase in reproductive intensity and spawning in Austral winter (April–May), evidenced by the loss of mature spermatozoa and ripe oocytes from males and females, respectively. The simultaneous occurrence of these contrasting traits in individuals is attributed to a flexible feeding strategy (suspension and deposit feeding) in response to seasonal changes in food supply characteristic of the Antarctic marine environment. Asynchrony between individual females is also notable. We hypothesise that the variability may represent a trade-off between somatic and reproductive growth, and previously reported internal interannual cycles in shell growth.

Broadcast spawning invertebrates in the Antarctic encounter a very arduous and unforgiving environment, where consistently low temperatures, high seawater viscosities and at times high flow conditions undermine successful sperm-egg interactions. The fertilization traits of the circumpolar Antarctic seastar Odontaster validus, were analyzed from diver-collected monthly samples from a shallow water site adjacent to the British Antarctic Survey (BAS) Rothera Research Station (Western Antarctic Peninsula). Dives were conducted using opencircuit scuba between 15–20 m depths. Successful sperm-egg interactions varied amongst seastars, however there was an optimum range in sperm concentration over which high numbers of eggs were fertilized (105–106 sperm⋅mL-1). This Antarctic seastar required 1–2 orders of magnitude more sperm to ensure optimal fertilization success compared to several comparable temperate species and the longevity of spermatozoa was moderate, retaining some activity and minimal fertilizing ability up to 24 hours after release. Eggs and sperm released by O. validus were also highly stenothermal, with extremely narrow ranges of thermal tolerance. Therefore, even small modifications in temperature dramatically reduced the number of eggs fertilized. This has important implications for the geographical distribution of Antarctic invertebrates, but also confirms the susceptibility of these species to environmental modification, making them one of the most temperature sensitive fauna on Earth. Such stenothermy is of particular relevance if ocean warming and the 1–2ºC rise in global temperature, predicted over the next century, is realized.

Waters around the Antarctic Peninsula are experiencing one of the fastest rates of warming seen anywhere on Earth in the sea in recent times. Species inhabiting nearshore seabed sites in Antarctica have a long history in near freezing temperatures and have poor physiological capacities to cope with change. Reproductive success is a vital characteristic in species survival and evaluation of how reproductive processes vary with time is key to identifying vulnerable species and evaluating the effects of ocean warming. The long-term gametogenic development of the nemertean Parborlasia corrugatus (McIntosh, 1876) was analysed from monthly samples collected between July 1997 and November 2000 from a shallow water site adjacent to the British Antarctic Survey Rothera Research Station (Western Antarctic Peninsula). Spermatogenesis, oocyte size and reproductive condition are described for each month using histological and image analysis techniques. Male and female reproductive condition varied seasonally, with a reduction in the proportion of large oocytes and mature sperm in the gonad during the late austral summer (December–March). We identify three key characteristics in the reproductive ecology of P. corrugatus (1) the timing of reproduction was consistent in the late austral summer of each year and synchronous between males and females (2) oogenesis progressed over a discrete 15–16 month period with a single generation of oocytes in the ovary during most stages of gametogenic development and (3) notable differences in reproductive condition were not apparent from year to year. The majority of long-term studies on reproductive ecology of marine invertebrates at high latitudes, with the exception of one or two species, revealed that 18–24 months are required for gametogenesis compared to 6–12 months in temperate species and there is extreme inter-annual variation in reproductive output. P. corrugatus differs from this in requiring only 15 months for gametogenesis, and has