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[1] From time series of dissolved oxygen (O 2 ), phosphate (PO 4 ) and water temperature (T) during the last forty years in the Japan Sea Deep Water and the North Pacific Intermediate Water, we found that O 2 , PO 4 and T show a clear bidecadal oscillations of about 18 years superimposed on the linear trends of decrease of 0.47 mmol-O 2 kg À1 yr À1 and increase of 0.003 mmol-PO 4 kg À1 yr À1 and 0.005°C yr À1 in both two oceanic areas. The changes of O 2 , PO 4 and T in the two oceanic areas were synchronized despite the water formation systems of each area being independent. Both the linear trends and the oscillations of O 2 , PO 4 and T in the two oceanic areas also showed a strong correlation with the anomaly of the sea surface level pressure in the North Pacific that possibly affects the change of surface oceanic condition.

Antarctic krill embryos and larvae were experimentally exposed to 380 (control), 1000 and 2000 µatm p CO 2 in order to assess the possible impact of ocean acidification on early development of krill. No significant effects were detected on embryonic development or larval behaviour at 1000 µatm p CO 2 ; however, at 2000 µatm p CO 2 development was disrupted before gastrulation in 90 per cent of embryos, and no larvae hatched successfully. Our model projections demonstrated that Southern Ocean sea water p CO 2 could rise up to 1400 µatm in krill's depth range under the IPCC IS92a scenario by the year 2100 (atmospheric p CO 2 788 µatm). These results point out the urgent need for understanding the p CO 2 -response relationship for krill developmental and later stages, in order to predict the possible fate of this key species in the Southern Ocean.

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