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McMurdo Sound (mcmurdo + sound)
Selected AbstractsThe Geologic Basis for a Reconstruction of a Grounded Ice Sheet in McMurdo Sound, Antarctica, at the Last Glacial MaximumGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 2-3 2000George H. Denton A grounded ice sheet fed from the Ross Embayment filled McMurdo Sound at the last glacial maximum (LGM). This sheet deposited the little-weathered Ross Sea drift sheet, with far-traveled Transantarctic Mountains (TAM) erratics, on lower slopes of volcanic islands and peninsulas in the Sound, as well as on coastal forelands along the TAM front. The mapped upper limit of this drift, commonly marked by a distinctive moraine ridge, shows that the ice-sheet surface sloped landward across McMurdo Sound from 710 m elevation at Cape Crozier to 250 m in the eastern foothills of the Royal Society Range. Ice from the Ross Embayment flowed westward into the sound from both north and south of Ross Island. The northern flowlines were dominant, deflecting the southern flowlines toward the foothills of the southern Royal Society Range. Ice of the northern flowlines distributed distinctive kenyte erratics, derived from western Ross Island, in Ross Sea drift along the TAM front between Taylor and Miers Valleys. Lobes from grounded ice in McMurdo Sound blocked the mouths of TAM ice-free valleys, damming extensive proglacial lakes. A floating ice cover on each lake formed a conveyor that transported glacial debris from the grounded ice lobes deep into the valleys to deposit a unique glaciolacustrine facies of Ross Sea drift. The ice sheet in McMurdo Sound became grounded after 26,860 14C yr bp. It remained near its LGM position between 23,800 14C yr bp and 12,700 14C yr bp. Recession was then slow until sometime after 10,794 14C yr bp. Grounded ice lingered in New Harbor in the mouth of Taylor Valley until 8340 14C yr bp. The southward-retreating ice-sheet grounding line had penetrated deep into McMurdo Sound by 6500 14C yr bp. The existence of a thick ice sheet in McMurdo Sound is strong evidence for widespread grounding across the Ross Embayment at the LGM. Otherwise, the ice-sheet surface would not have sloped landward, nor could TAM erratics have been glacially transported westward into McMurdo Sound from farther offshore in the Ross Embayment. [source] Antarctic fish can survive prolonged exposure to elevated temperaturesJOURNAL OF FISH BIOLOGY, Issue 7 2008E. Robinson The Antarctic notothenioid Pagothenia borchgrevinki was collected from the stenothermal waters of McMurdo Sound in the summers of 2004, 2005 and 2006. Acclimation ability at 4° C was tested in healthy P. borchgrevinki and in individuals infected with x-cell gill disease. All healthy fish successfully acclimated to 4° C, establishing compensatory changes in resting oxygen consumption rate (Rrest) and critical swimming speed (Ucrit) during a 1 month acclimation period, which were maintained during a longer, 6 month acclimation period. In contrast, individuals infected with x-cell disease were unable to acclimate to 4° C, demonstrating significantly reduced survival rates compared with healthy individuals at 4° C. Measurements of Rrest suggest that limitations in the ability of x-cell fish to uptake oxygen from the external milieu may have a negative effect on their survival at 4° C. [source] Dinucleotide microsatellite markers from the Antarctic seals and their use in other PinnipedsMOLECULAR ECOLOGY RESOURCES, Issue 3 2002C. S. Davis Abstract Twenty-four microsatellite loci were isolated from three species of Antarctic seals (Subfamily Monachinae, Tribe Lobodontini). Eleven loci were cloned from Weddell seal, Leptonychotes weddellii, seven from leopard seal, Hydrurga leptonyx, and six from crabeater seal, Lobodon carcinophagus. Variability was assessed in Weddell seals collected in McMurdo Sound, leopard seals from Bird Island, South Georgia, and crabeater seals sampled in the eastern Ross Sea. All loci were variable in the three species used for cloning and 22 of these loci amplified variable products in the Ross seal, Ommatophoca rossii. Cross-species amplification was largely successful, with an average of 19 loci amplifying products in other phocids. [source] The initial journey of juvenile emperor penguinsAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue S1 2007Gerald L. Kooyman Abstract 1.The first major journey of emperor penguins, among several in their lifetime, is the juveniles' dispersal from their natal colony on a trip that takes them beyond Antarctic waters. The route taken by fledglings from Cape Washington (74.5°,S; 165.4°,E) was studied by applying satellite transmitters to ten individuals during December 1994,1996. In January 2001 transmitters with longer transmission capacity were also applied to six hand-fed fledglings, which had been held captive for one month while attaining a body mass exceeding that of wild birds. These post-captive birds were released at the ice edge of McMurdo Sound (77.5°,S; 165.0°,E), which is in the vicinity of other emperor penguin colonies, and 320,km south of their natal colony of Cape Washington. 2.Independent of their parents, the wild birds travelled north-east for the next two months, reaching locations as low as 57°,S. The post-captive birds travelled north also, but their trek reached only to about 63°,S before they turned south, or remained near their most northerly position from March through May. 3.It was concluded that among colonies in the southern Ross Sea: (a) most healthy fledglings survive at least the first two months at sea, feeding themselves as they go; (b) the Cape Washington fledglings travelled as far north as 57°,S, and much of this journey was in ice free waters; (c) by April, the post-captive birds reached at least as far as the large-scale pack ice edge and possibly beyond the edge at 63°,S; (d) by early March the trend north ends, and by about late March the birds travel to, or remain near the northern ice edge. 4.The reason the birds travel so far north remains a mystery. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||