Victoria University

Distribution of Modern Benthic Foraminifera of McMurdo Sound, Antarctica

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dc.contributor.advisor Vella, Paul
dc.contributor.advisor Barrett, Peter Ward, Barbara Lynne 2008-10-02T02:54:31Z 2008-10-02T02:54:31Z 1984 1984
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 per mil and -1.8 degrees 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.iso en_NZ
dc.publisher Victoria University of Wellington en_NZ
dc.subject Foraminifera en_NZ
dc.subject Paleontology en_NZ
dc.subject Calcareous species en_NZ
dc.subject Antarctic regions en_NZ
dc.subject Agglutinated species en_NZ
dc.title Distribution of Modern Benthic Foraminifera of McMurdo Sound, Antarctica en_NZ
dc.type Text en_NZ
vuwschema.contributor.unit School of Geography, Environment and Earth Sciences en_NZ
vuwschema.subject.marsden 260112 Palaeontology en_NZ
vuwschema.type.vuw Awarded Doctoral Thesis en_NZ Geology en_NZ Victoria University of Wellington en_NZ Doctoral en_NZ Doctor of Philosophy en_NZ
vuwschema.subject.anzsrcfor 049999 Earth Sciences not elsewhere classified en_NZ

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