Antarctic ice sheet discharge driven by atmosphere-ocean feedbacks at the Last Glacial Termination

Reconstructing the dynamic response of the Antarctic ice sheets to warming during the Last Glacial Termination (LGT; 18,000–11,650 yrs ago) allows us to disentangle ice-climate feedbacks that are key to improving future projections. Whilst the sequence of events during this period is reasonably well-known, relatively poor chronological control has precluded precise alignment of ice, atmospheric and marine records, making it difficult to assess relationships between Antarctic ice-sheet (AIS) dynamics, climate change and sea level. Here we present results from a highly-resolved ‘horizontal ice core’ from the Weddell Sea Embayment, which records millennial-scale AIS dynamics across this extensive region. Counterintuitively, we find AIS mass-loss across the full duration of the Antarctic Cold Reversal (ACR; 14,600–12,700 yrs ago), with stabilisation during the subsequent millennia of atmospheric warming. Earth-system and ice-sheet modelling suggests these contrasting trends were likely Antarctic-wide, sustained by feedbacks amplified by the delivery of Circumpolar Deep Water onto the continental shelf. Given the anti-phase relationship between inter-hemispheric climate trends across the LGT our findings demonstrate that Southern Ocean-AIS feedbacks were controlled by global atmospheric teleconnections. With increasing stratification of the Southern Ocean and intensification of mid-latitude westerly winds today, such teleconnections could amplify AIS mass loss and accelerate global sea-level rise.

Effect of Storage at Low Temperatures on Development and Survival of Postparasitic Juveniles of Romanomermis culicivorax (Nematoda: Mermithidae)

Development of postparasites and adult females of Romanomermis culicivorax Ross and Smith, 1976 may be retarded by keeping cultures at 10 or 15 C for 15 wk. Storage at 5 C resulted in high mortality of postparasites. A storage temperature of 10 C is suitable if development of postparasites, young adults, and gravid females is to be greatly retarded. None of the females were gravid when postparasites (1-6 days old) were kept at 10 C for 15 wk. Development resumed after the cultures were returned to 26 C and no significant mortality occurred. A storage temperature of 15 C is suitable if development is to be only moderately retarded. After a 15-wk storage period, only a few weeks were required to return the cultures to full production status.

Embryonic development of Romanomermis communensis (Nematoda:Mermithidae) at different temperatures

Embryos of R. communensis completed their development to the late coil stage in 16.5 days at 20 °C, 22 days at 15 °C, and 32 days at 10 °C. Embryos failed to develop at 5 °C, although 10% did reach the two-cell stage by 32 days. About 5% of the eggs at 20 and 15 °C hatched after embryonation was completed. There was no further hatching during the 32-day period of observation. The nematode is probably univoltine in its natural habitat near Churchill, Manitoba.