Sea floor sediments of McMurdo Sound were sampled to obtain material suitable for detailed analysis of foraminiferal populations and their relationships to sediment type and ecological factors. Areas sampled, using the sea-ice as platform, were New Harbour and near the McMurdo Station desalination plant discharge point. Later in the season during January and February, Drs. D. Bennett and F. Davey obtained five gravity cores for this work during a seismic profiling cruise on board the Benjamin Bowring. These were from open-water areas inaccessible from the sea ice earlier in the season. Figure 1 is a map of the McMurdo Sound area showing sample locations for all material collected this past season; depths ranged from 8 to 750m.

A total of 29 core and grab samples were obtained by dropping equipment through a twelve inch access hole drilled in the two metre thick sea ice (Plate II A.B.C.D.). Twenty-seven of these were large enough for analysis. The additional five gravity cores have been split horizontally into one or two centimetre segments to yield 24 samples. The total number of samples to be analysed from this season is 51.

Preliminary examination of material obtained during the 1979-80 season and this past season indicates variation of foraminiferal populations between open McMurdo Sound waters and the embayed New Harbour area. Agglutinated species predominate in the muddier, enclosed New Harbour sediments, while calcareous forms are more prevalent in the deeper open Sound waters. Varying amounts of sponge mat have been found at several sites but these seem to have little effect on the species present.

Next season (1981-82) we plan to continue the sampling programme, using our modified large-diameter sphincter corer, as well as a salinity-temperature bridge, current meter, tide gauge, and underwater camera. The areas to be covered are southern McMurdo Sound and Granite Harbour.

Figure 1: Map of McMurdo Sound, showing this season's sea floor sampling sites and position of the seismic survey lines.