• European Marine Science
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Bats and birds are key providers of ecosystem services in forests. How climate and habitat jointly shape their communities is well studied, but whether biotic predictors from other trophic levels may improve bird and bat diversity models is less known, especially across large bioclimatic gradients. Here, we achieved multi-taxa surveys in 209 mature forests replicated in six European countries from Spain to Finland, to investigate the importance of biotic predictors (i.e. the abundance or activity of defoliating insects, spiders, earthworms and wild ungulates) for bat and bird taxonomic and functional diversity. We found that nine out of 12 bird and bat diversity metrics were best explained when biotic factors were added to models including climate and habitat variables, with a mean gain in explained variance of 38% for birds and 15% for bats. Tree functional diversity was the most important habitat predictor for birds, while bats responded more to understorey structure. The best biotic predictors for birds were spider abundance and defoliating insect activity, while only bat functional evenness responded positively to insect herbivory. Accounting for potential biotic interactions between bats, birds and other taxa of lower trophic levels will help to understand how environmental changes along large biogeographical gradients affect higher-level predator diversity in forest ecosystems.

The seasonal and spatial variability of dissolved Barium (Ba) in the Amundsen Gulf, southeastern Beaufort Sea, was monitored over a full year from September 2007 to September 2008. Dissolved Ba displays a nutrient-type behavior: the maximum water column concentration is located below the surface layer. The highest Ba concentrations are typically observed at river mouths, the lowest concentrations are found in water masses of Atlantic origin. Barium concentrations decrease eastward through the Canadian Arctic Archipelago. Barite (BaSO4) saturation is reached at the maximum dissolved Ba concentrations in the subsurface layer, whereas the rest of the water column is undersaturated. A three end-member mixing model comprising freshwater from sea-ice melt and rivers, as well as upper halocline water, is used to establish their relative contributions to the Ba concentrations in the upper water column of the Amundsen Gulf. Based on water column and riverine Ba contributions, we assess the depletion of dissolved Ba by formation and sinking of biologically bound Ba (bio-Ba), from which we derive an estimate of the carbon export production. In the upper 50 m of the water column of the Amundsen Gulf, riverine Ba accounts for up to 15% of the available dissolved Ba inventory, of which up to 20% is depleted by bio-Ba formation and export. Since riverine inputs and Ba export occur concurrently, the seasonal variability of dissolved Ba in the upper water column is moderate. Assuming a fixed organic carbon to bio-Ba flux ratio, carbon export out of the surface layer is estimated at 1.8 ± 0.45 mol C m‑2 yr‑1. Finally, we propose a climatological carbon budget for the Amundsen Gulf based on recent literature data and our findings, the latter bridging the surface and subsurface water carbon cycles. International audience

Abstract. The Greenland ice sheet is one of the largest contributors to global meansea-level rise today and is expected to continue to lose mass as the Arcticcontinues to warm. The two predominant mass loss mechanisms are increasedsurface meltwater run-off and mass loss associated with the retreat ofmarine-terminating outlet glaciers. In this paper we use a large ensemble ofGreenland ice sheet models forced by output from a representative subset ofthe Coupled Model Intercomparison Project (CMIP5) global climate models to project ice sheet changes and sea-level risecontributions over the 21st century. The simulations are part of theIce Sheet Model Intercomparison Project for CMIP6 (ISMIP6). We estimate thesea-level contribution together with uncertainties due to future climateforcing, ice sheet model formulations and ocean forcing for the twogreenhouse gas concentration scenarios RCP8.5 and RCP2.6. The resultsindicate that the Greenland ice sheet will continue to lose mass in bothscenarios until 2100, with contributions of 90±50 and 32±17 mm to sea-level rise for RCP8.5 and RCP2.6, respectively. The largestmass loss is expected from the south-west of Greenland, which is governed bysurface mass balance changes, continuing what is already observed today.Because the contributions are calculated against an unforced controlexperiment, these numbers do not include any committed mass loss, i.e. massloss that would occur over the coming century if the climate forcingremained constant. Under RCP8.5 forcing, ice sheet model uncertaintyexplains an ensemble spread of 40 mm, while climate model uncertainty andocean forcing uncertainty account for a spread of 36 and 19 mm,respectively. Apart from those formally derived uncertainty ranges, thelargest gap in our knowledge is about the physical understanding andimplementation of the calving process, i.e. the interaction of the ice sheetwith the ocean. info:eu-repo/semantics/published

In January 2017, the International Seabed Authority released a discussion paper on the development of Environmental Regulations for deep-sea mining (DSM) within the Area Beyond National Jurisdiction (the “Area”). With the release of this paper, the prospect for commercial mining in the Area within the next decade has become very real. Moreover, within nations’ Exclusive Economic Zones, the exploitation of deep-sea mineral ore resources could take place on very much shorter time scales and, indeed, may have already started. However, potentially toxic metal mixtures may be released at sea during different stages of the mining process and in different physical phases (dissolved or particulate). As toxicants, metals can disrupt organism physiology and performance, and therefore may impact whole populations, leading to ecosystem scale effects. A challenge to the prediction of toxicity is that deep-sea ore deposits include complex mixtures of minerals, including potentially toxic metals such as copper, cadmium, zinc, and lead, as well as rare earth elements. Whereas the individual toxicity of some of these dissolved metals has been established in laboratory studies, the complex and variable mineral composition of seabed resources makes the a priori prediction of the toxic risk of DSM extremely challenging. Furthermore, although extensive data quantify the toxicity of metals in solution in shallow-water organisms, these may not be representative of the toxicity in deep-sea organisms, which may differ biochemically and physiologically and which will experience those toxicants under conditions of low temperature, high hydrostatic pressure, and potentially altered pH. In this synthesis, we present a summation of recent advances in our understanding of the potential toxic impacts of metal exposure to deep-sea meio- to megafauna at low temperature and high pressure, and consider the limitation of deriving lethal limits based on the paradigm of exposure to single metals in solution. We consider the potential for long-term and farfield impacts to key benthic invertebrates, including the very real prospect of sub-lethal impacts and behavioral perturbation of exposed species. In conclusion, we advocate the adoption of an existing practical framework for characterizing bulk resource toxicity in advance of exploitation. info:eu-repo/semantics/publishedVersion

The Belgica cold-water coral banks on the eastern slope of the Porcupine Seabight are closely associated with bottom currents. In order to better understand the local temporal and spatial characteristics, as well as the palaeoclimatologic influences, a 26 m long core, taken on a small contourite drift, was studied. This sediment record of approximately 100 ka BP reveals new insights into the regional glacial and sedimentary processes, which are intrinsically linked to several geological, climatological, biological and hydrodynamic variables. The glacial sequences in the core contain six ice-rafting events (IRE). They are comparable with the North Atlantic Heinrich Events, although their characteristics show dominant influences from the proximal British-Irish Ice Sheet (BIIS). These IRE have a low magnetic susceptibility and are deposited during two or three ice-rafting pulses. The record of ice-rafting suggests a millennial-scaled BIIS destabilisation and confirms the start of a final retreat about 25 ka ago. Additionally, the glacial sequence corresponds to a muddy contourite, influenced by bottom-current strength variations during interstadials, possibly triggered by sporadic reintroductions of Mediterranean Outflow Water in a glacial North Atlantic Ocean. The interglacial sequence features an 11-m thick deep-water massive sand unit, probably deposited under a high-energy bottom-current regime.