The Antarctic intertidal zone is one of the world’s most extreme marine environments. As well as having a typically high annual temperature variation (~ 30 °C), it is affected by frequent ice scouring in summer and ice encasement in winter, as well as substantial salinity fluctuations during tidal cycles. For many years the Antarctic intertidal was believed to host only migratory species during summer, however, recent studies have found several permanently resident macrofaunal species, including the limpet Nacella concinna. Here we present results of the first seasonal comparison of different ecophysiological parameters in this species collected from the intertidal in both winter (August and September) and summer (January and February) on Adelaide Island (West Antarctic Peninsula). There was clear evidence of seasonal acclimatisation with a shift in thermal window between winter and summer limpets. The seasonal change in metabolic rate did not show increased costs in winter (cf metabolic cold adaptation) and the seasonal increase in oxygen consumption was within the range expected due to the physical effects of temperature alone. O:N ratios indicated that the animals were using the same metabolic substrate (mainly protein) all year round. There was no significant difference in condition factor between winter and early summer individuals. However comparisons with subtidal N. concinna showed that those from the intertidal had a lower condition factor than those permanently immersed. Whilst remaining in the ice-encased intertidal during winter may give access to ice-algae and microphytobenthos in the shallows and provide a feeding advantage early in the season, there are clearly extra costs to living in the intertidal per se. Hence N. concinna may not derive any obvious fitness advantage but may simply be occupying an available niche and surviving the physical challenges in the shallows.
View post tag: News by topic View post tag: Maritime View post tag: Naval View post tag: partner Maritime Partner Announces Contract with Ghana Ports, Harbours Authority View post tag: Navy April 26, 2012 Back to overview,Home naval-today Maritime Partner Announces Contract with Ghana Ports, Harbours Authority View post tag: contract View post tag: ports View post tag: Ghana Industry news View post tag: authority View post tag: Harbours View post tag: Announces Maritime Partner has announced their first contract with Ghana Ports and Harbours Authority.The contracts include delivery of a brand new design , Alusafe 1600 Security Patrol and Rescue Boat, various training of personnel and a spare part package. Delivery is set to late 2012.The craft will be installed with twin Volvo Penta D11-600 and Hamilton HJ 322 Waterjets which will give the boat a top speed of 35 knots.[mappress]Naval Today Staff , April 26, 2012; Image: maritime-partner Share this article
Professor Stephen Hawking, the celebrated physicist and cosmologist, is to give a free public lecture on black holes at the Oxford University Mathematics Institute on Wednesday January 18 at 5pm.Spaces were made available today and demand is expected to be very high. The Mathematics Institute will be podcasting the lecture live.He will speaking about black holes in the inaugural Roger Penrose lecture at the Royal Observatory Quarter on Woodstock Road.Prof Hawking is currently Director of Research at the Cambridge University Department of Applied Mathematics and Theoretical Physics.The Professor, now 74, was diagnosed with the motor neurone disease ALS at the age of 21.It will be the first lecture in a new series offered by the Mathematics Institute, in celebration of the lifetime’s contribution of Professor Roger Penrose.It was alongside Penrose that Hawking showed that Einstein’s General Theory of Relativity implied space and time would have a beginning in the Big Bang and an end in black holes.The lecture will be Hawking’s second address in Oxford in the space of three months, having spoken at the Union in November.His speech there – tickets for which sold out in minutes – warned that humans will die out within 1,000 years unless mankind leaves earth.People can email [email protected] to register to attend the event, and visit maths.ox.ac.uk for more details.Oxford University have been contacted for for comment.