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Assessing Biodiversity Declines Understanding human impact on biodiversity depends on sound quantitative projection. Pereira et al. (p. 1496 , published online 26 October) review quantitative scenarios that have been developed for four main areas of concern: species extinctions, species abundances and community structure, habitat loss and degradation, and shifts in the distribution of species and biomes. Declines in biodiversity are projected for the whole of the 21st century in all scenarios, but with a wide range of variation. Hoffmann et al. (p. 1503 , published online 26 October) draw on the results of five decades' worth of data collection, managed by the International Union for Conservation of Nature Species Survival Commission. A comprehensive synthesis of the conservation status of the world's vertebrates, based on an analysis of 25,780 species (approximately half of total vertebrate diversity), is presented: Approximately 20% of all vertebrate species are at risk of extinction in the wild, and 11% of threatened birds and 17% of threatened mammals have moved closer to extinction over time. Despite these trends, overall declines would have been significantly worse in the absence of conservation actions.

The Antarctic Peninsula is one of the most rapidly warming regions on Earth, as evidenced by a recent increase in the intensity and duration of summer melting, the recession of glaciers and the retreat and collapse of ice shelves. Despite this, only a limited number of well-dated near shore marine and lake sediment based palaeoenvironmental records exist from this region; so our understanding of the longer-term context of this rapid climate change is limited. Here we provide new well-dated constraints on the deglaciation history, and changes in sea ice and climate based on analyses of sedimentological proxies, diatoms and fossil pigments in a sediment core collected from an isolation basin on Beak Island in Prince Gustav Channel, NE Antarctic Peninsula (63°36′S, 57°20′W). Twenty two radiocarbon dates provided a chronology for the core including a minimum modelled age for deglaciation of 10,602 cal yr BP, following the onset of marine sedimentation. Conditions remained cold and perennial sea ice persisted in this part of Prince Gustav Channel until c. 9372 cal yr BP. This was followed by a seasonally open marine environment until at least 6988 cal yr BP, corresponding with the early retreat and disintegration of the ice shelf in southern Prince Gustav Channel. Following isolation of the basin from 6988 cal yr BP a relatively cold climate persisted until 3169 cal yr BP. A Mid-late Holocene climate optimum occurred between 3169 and 2120 cal yr BP, inferred from multiple indicators of increased biological production. This postdates the onset of the Mid-late Holocene climate optimum in the South Shetland Islands (4380 cal yr BP) and the South Orkney Islands (3800 cal yr BP) suggesting that cooler climate systems of the Weddell Sea Gyre to the east of the Peninsula may have buffered the onset of warming. Climate deterioration is inferred from c. 2120 cal yr BP until 543 cal yr BP. This was followed by warming. Superimposed on this warming trend, the instrumental record of recent warming at nearby Hope Bay is mirrored by a recent increase in the lake’s primary production and a shift in the diatom communities in the uppermost 3 cm of sediments, suggesting that this is amongst the first records to show an ecological response to recent rapid temperature increase. These new constraints on glaciological and climate events in Prince Gustav Channel are reviewed in the context of wider changes in the Antarctic region. Peer reviewed

The current downturn of the arctic cryosphere, such as the strong loss of sea ice, melting of ice sheets and glaciers, and permafrost thaw, affects the marine and terrestrial carbon cycles in numerous interconnected ways. Nonetheless, processes in the ocean and on land have been too often considered in isolation while it has become increasingly clear that the two environments are strongly connected: Sea ice decline is one of the main causes of the rapid warming of the Arctic, and the flow of carbon from rivers into the Arctic Ocean affects marine processes and the air-sea exchange of CO2. This review, therefore, provides an overview of the current state of knowledge of the arctic terrestrial and marine carbon cycle, connections in between, and how this complex system is affected by climate change and a declining cryosphere. Ultimately, better knowledge of biogeochemical processes combined with improved model representations of ocean-land interactions are essential to accurately predict the development of arctic ecosystems and associated climate feedbacks.

AbstractNature-based solutions, such as shellfish reefs, can support natural coastal defence and be a potential solution for climate-resilient shorelines in the future. In the Belgian Part of the North Sea, the “Coastbusters” projects aim to develop nature-based coastal protection by favouring subtidal mussel bed establishment on the seafloor through typical longline aquaculture techniques. Mussel beds are dependent on environmental conditions, and both influence the physical and biogeochemical features in a soft-sediment environment. Therefore, a comprehensive ecological monitoring program is essential to assess the success of future mussel bed development and its influence on the surrounding ecosystem. For establishing a monitoring baseline of the two experimental areas, a combination of conventional benthic assessment methods (grab sampling and granulometry) and non-invasive techniques (sediment profile imaging and transect diving video surveys) were utilised. Although mussel reefs did not yet develop by the time of this study, clear differences in ecological and sedimentological characteristics were found between two experimental areas (sheltered and exposed), subjected to slightly different hydrodynamic conditions. The one sheltered by coastal sandbanks was dominated by fine-muddy sand, higher species richness, biomass, and higher biological activity (burrows, fauna, and biological beds) as observed by all methods in one or another way. Moreover, functional diversity indices revealed a higher partitioning of the total available resources, suggesting more complex ecological processes in the sheltered area. Conversely, the area more exposed to the open sea was dominated by more sandy sediments, and fewer organisms were found. The combination of those different monitoring tools provides an integrated, complementary view, from different perspectives, on the biological, physical and functional characteristics of the study areas.

The Wadden Sea has an important role for marine mammals in terms of resting, nursing and foraging. Harbor seal is the most abundant marine mammal species in this area. The use of the food resources of the Wadden Sea by seals is not clear, and previous studies showed that this species can travel kilometers away from their haul-outs to forage in the North Sea. In this study, we analyzed the stable isotopes of vibrissae from 23 dead harbor seals found on the island of Sylt to investigate their diet. The predator´s carbon and nitrogen isotope compositions were compared to the compositions of different potential prey items from the Sylt-Rømø Bight and from the North Sea in order to study seasonal pattern in the diet and in the foraging location. In parallel, seasonal variation of abundance and biomass of the potential prey items from the Sylt-Rømø Bight were studied and compare to their contribution to the seal´s diet. The results revealed a change in the seal´s diet from pelagic sources in spring to a benthic based diet in summer, and an increasing use of the North Sea resources in fall and winter in accordance with the seasonal variation of the availability of prey in the Sylt-Rømø Bight.