Ecophysiology and ecological limits of symbiotrophic vesicomyid bivalves (Pliocardiinae) in the Southern Ocean

first_imgGeothermal energy provides an important resource in Antarctic marine ecosystems, exemplified by the recent discovery of large-sized chemosymbiotic vesicomyid bivalves (subfamily Pliocardiinae) in the Southern Ocean. These clams, which we identified as Archivesica s.l. puertodeseadoi, have been reported as dead shells in areas previously covered by Larsen A and B ice shelves (eastern Antarctic Peninsula) and as live animals from active hydrothermal sites in the Kemp Caldera (South Sandwich Arc) at depths of 852–1487 m. Before, A. puertodeseadoi was known only from its type locality in the Argentine Sea, so we considerably extend the range of the species. Observations taken by remotely operated vehicle (ROV) footage show that the clams can live buried in sediment, or epilithically on the surface of rocks in diffuse geothermal flow. Experimental respirometry was conducted at surface pressure on individual bivalves acclimated to either their habitat temperature (4 °C) or elevated temperature (10 °C). The range of standard metabolic rates, from 3.13 to 6.59 (MO2, μmol O2 h−1 g−1 dry tissue mass), is similar to rates measured ex situ for other species in this clade, and rates did not differ significantly between temperature groups. Taken together, these data indicate a range of ecophysiological flexibility for A. puertodeseadoi. Although adapted to a specialist mode of life, this bivalve exploits a relatively broad range of habitats in the Southern Ocean: within sulphidic sediments, epilithically in the presence of diffuse sulphidic flow, or in deep methane-enriched seawater trapped under ice.last_img read more

Speech: PM press statement at European Council: 14 December 2018

first_img That the EU stands ready to embark on preparations so that negotiations on the future partnership can start as soon as possible. As formal conclusions, these commitments have legal status and therefore should be welcomed.As I have always said, the guaranteed way of avoiding the backstop is to have the future partnership in place by the time the implementation period is over. The EU is very firmly committed to this course.But MPs will require further assurances, and I have discussed that this morning with my EU partners, including Presidents Tusk, Juncker and others.I note there has been reporting that the EU is not willing to consider any further clarification. The EU is clear – as I am – that if we are going to leave with a deal this is it.But my discussions with colleagues today have shown that further clarification and discussion following the Council’s conclusions is in fact possible.There is work still to do and we will be holding talks in coming days about how to obtain the further assurances that the UK Parliament needs in order to be able to approve the deal.I say again. It is in the overwhelming interest of all our people – in the EU and the UK – to get this done, and as quickly as possible. If the backstop was ever triggered, it would apply only temporarily and the EU would use its best endeavours to negotiate and conclude expeditiously a subsequent agreement that would replace the backstop. At this Council meeting, I have held a series of discussions with my fellow leaders on the Brexit deal and I was crystal clear about the assurances which are needed on the backstop having heard the views of MPs in the House of Commons.I reiterated that it is in the interests of the EU as well as the UK to get this over the line. A disorderly Brexit would be good for no-one.At 27 level, the EU have published a series of conclusions.The EU made clear: that it is their firm determination to work speedily on a future relationship or alternative arrangements which ensure no hard border by 31 December 2020 so that the backstop will not need to be triggered.last_img read more