(Table 3) Sedimentation rates of stage 1 and last glacial maximum from different Holes during cruises of RRS Discovery in 1984-1985 and 1987-1988, and RRS James Clark Ross in 1992-1993

Within the Scotia Sea, the axis of the Antarctic Circumpolar Current (ACC) is geographically confined, and sediments therefore contain a record of palaeo-flow speed uncomplicated by ACC axis migration. We outline Holocene and Last Glacial Maximum (LGM) current-controlled sedimentation using data from 3.5-kHz profiles, cores and current meter moorings. Geophysical surveys show areas of erosion and deposition controlled by Neogene basement topography. Deposition occurs in mounded sediment drifts or flatter areas, where 500-1000 m of sediment overlies acoustic basement. 3.5-kHz profiles show parallel, continuous sub-bottom reflectors with highest sedimentation rates in the centre of the drifts, and reflectors converging towards marginal zones of non-deposition. Locally, on the flanks of continental blocks (e.g. South Georgia), downslope processes are dominant. The absence of mudwaves on the sediment drifts may result from the unsteadiness of ACC flow. A core transect from the ACC axis south to the boundary with the Weddell Gyre shows a southward decrease in biogenic content, controlled by the Polar Front and the spring sea-ice edge. Both these features lay farther north at LGM. The cores have been dated by relative abundance of the radiolarian Cycladophora davisiana, and by changes in the biogenic Ba content, a palaeoproductivity indicator. Sedimentation rates range from 3 to 17 cm/ka. The grain size of Holocene sediments shows a coarsening trend from south to north, consistent with strongest bottom-current flow near the ACC axis, though interpretation is complicated by the presence of biogenic grains. Year-long current meter records indicate mean speeds from 7 cm/s in the south to 12 cm/s in the north, with benthic storm frequency increasing northwards. LGM sediments are predominantly terrigenous and show a clearer northward-coarsening trend, with well-sorted silts in the northern Scotia Sea. Assuming a constant terrigenous source, this implies stronger ACC flow at the LGM, contrasting with weaker Weddell Gyre flow deduced from earlier work.

Seagrass and associated benthic community data derived from field surveys at Low Isles, Great Barrier Reef, conducted July-August, 1997

The distribution of seagrass and associated benthic communities on the reef and lagoon of Low Isles, Great Barrier Reef, was mapped between the 29 July and 29 August 1997. For this survey, observers walked or free-dived at survey points positioned approximately 50 m apart along a series of transects. Visual estimates of above-ground seagrass biomass and % cover of each benthos and substrate type were recorded at each survey point. A differential handheld global positioning system (GPS) was used to locate each survey point (accuracy ±3m). A total of 349 benthic survey points were examined. To assist with mapping meadow/habitat type boundaries, an additional 177 field points were assessed and a georeferenced 1:12,000 aerial photograph (26th August 1997) was used as a secondary source of information. Bathymetric data (elevation below Mean Sea Level) measured at each point assessed and from Ellison (1997) supplemented information used to determine boundaries, particularly in the subtidal lagoon. 127.8 ±29.6 hectares was mapped. Seagrass and associated benthic community data was derived by haphazardly placing 3 quadrats (0.25m**2) at each survey point. Seagrass above ground biomass (standing crop, grams dry weight (g DW m**-2)) was determined within each quadrat using a non-destructive visual estimates of biomass technique and the seagrass species present identified. In addition, the cover of all benthos was measured within each of the 3 quadrats using a systematic 5 point method. For each quadrat, frequency of occurrence for each benthic category was converted to a percentage of the total number of points (5 per quadrat). Data are presented as the average of the 3 quadrats at each point. Polygons of discrete seagrass meadow/habitat type boundaries were created using the on-screen digitising functions of ArcGIS (ESRI Inc.), differentiated on the basis of colour, texture, and the geomorphic and geographical context. The resulting seagrass and benthic cover data of each survey point and for each seagrass meadow/habitat type was linked to GPS coordinates, saved as an ArcMap point and polygon shapefile, respectively, and projected to Universal Transverse Mercator WGS84 Zone 55 South.

Respiration rate of Microsetella norvegica collected during James Cook cruise JC087

Respiration of Microsetella norvegica was measured at PAP site during two days, using a UNISENSE microrespiration system and microelectrodes for O2. 10-20 starved Microsetella individuals were carefully placed into 2-ml respiration chambers in filtered sea water, and their respiration was measured for 20 min. The respiration rate was calculated based on the slope of the decrease in oxygen against time in the respiration chamber containing Microsetella, compared to the control where only filtered seawater was present. In total 18 measurements were conducted.