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Distribution of Modern Benthic Foraminifera of McMurdo Sound, Antarctica

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dc.contributor.author Ward, Barbara Lynne
dc.date.accessioned 2008-08-11T03:30:50Z
dc.date.accessioned 2022-10-27T02:51:42Z
dc.date.available 2008-08-11T03:30:50Z
dc.date.available 2022-10-27T02:51:42Z
dc.date.copyright 1984
dc.date.issued 1984
dc.identifier.uri https://ir.wgtn.ac.nz/handle/123456789/25595
dc.description.abstract This thesis presents the results of a study of benthic foraminifera from McMurdo Sound, Antarctica. The sound is 50 km across and more than 900 m deep, and is ice-covered for at least 9 months of the year. However, salinity and temperature of the bottom waters are constant (35‰ and -1.8° C). Sea floor sediment is mainly fine sand and mud with a little ice-rafted gravel. The aim of the study was to document the distribution of living and dead foraminifera and to determine the factor(s) controlling it. The twenty-six sites in water from 76 to 856m deep were sampled by gravity corer and grab, and nearly 40,000 specimens (2334 living and 36,875 dead) were identified. Three present day assemblages can be recognised: 1. Shallow open water assemblage (SWA): Trochammina glabra, Cribrostomoides jeffreysii, Trifarina earlandi, Ehrenbergina glabra, Fursenkoina earlandi and Globocassidulina crassa. 2. Deep open water assemblage (DWA): Reophax pilulifer, Reophax subdentaliniformis, Portotrochammina antarctica, Textularia antarctica and Miliammina arenacea. 3. Harbour/enclosed basin assemblage (HA): Reophax subdentaliniformis, Portotrochammina antarctica, Textularia antarctica, Fursenkoina earlandi and Globocassidulina crassa. The composition of the assemblages is controlled largely by calcium carbonate compensation depth (CCD). Calcareous species are abundant and varied (84 calcareous species) in the SWA above 620m, but are virtually absent from the DWA, which is found in deeper water. The dominance of agglutinated foraminifera in the HA indicates an even shallower CCD (about 270m) in restricted coastal settings. Death assemblages have a similar species diversity to corresponding life assemblages and are reasonably representative of them, except for the 200m zone above the offshore CCD, where death assemblages are depleted in calcareous taxa. The diversity of the agglutinated component of each assemblage remains nearly constant in all habitats and at all water depths, even though shallow water samples include a range of calcareous species. Thus competition from calcareous species appears not to be a stress factor for agglutinated species, which are considered to have reached the limit of their evolutionary potential in these waters. en_NZ
dc.language en_NZ
dc.language.iso en_NZ
dc.publisher Te Herenga Waka—Victoria University of Wellington en_NZ
dc.title Distribution of Modern Benthic Foraminifera of McMurdo Sound, Antarctica en_NZ
dc.type Text en_NZ
vuwschema.type.vuw Awarded Doctoral Thesis en_NZ
thesis.degree.grantor Te Herenga Waka—Victoria University of Wellington en_NZ
thesis.degree.level Doctoral en_NZ
thesis.degree.name Doctor of Philosophy en_NZ


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