Historical observations of the large-scale flow and frontal structure of the Antarctic Circumpolar Current in the Scotia Sea region were combined with the wind-induced surface Ekman transport to produce a composite flow field. This was used with a Lagrangian model to investigate transport of Antarctic krill. Particle displacements from known krill spawning areas that result from surface Ekman drift, a composite large-scale flow, and the combination of the two were calculated. Surface Ekman drift alone only transports particles a few kilometres over the 150-day krill larval development time. The large-scale composite flow moves particles several hundreds of kilometres over the same time, suggesting this is the primary transport mechanism. An important contribution of the surface Ekman drift on particles released along the continental shelf break west of the Antarctic Peninsula is moving them north-northeast into the high-speed core of the southern Antarctic Circumpolar Current Front, which then transports the particles to South Georgia in about 140–160 days. Similar particle displacement calculations using surface flow fields obtained from the Fine Resolution Antarctic Model do not show overall transport from the Antarctic Peninsula to South Georgia due to the inaccurate position of the southern Antarctic Circumpolar Current Front in the simulated circulation fields. The particle transit times obtained with the composite large-scale flow field are consistent with regional abundances of larval krill developmental stages collected in the Scotia Sea. These results strongly suggest that krill populations west of the Antarctic Peninsula provide the source for the krill populations found around South Georgia.

Body size, geographical distribution and biomass make Laternula elliptica one of the most important bivalve species of the Antarctic. A complete study on the population dynamics (reproduction cycle, growth, mortality and productivity) of this species from King George Island gave growth parameters for the von-Bertalanffy-growth-function of: L∞ = 112.2 mm, K = 0.160 yr 1, t0 = 0.000 yr. Total mortality was estimated as Z = 0.392 yr−1. Somatic production and mean biomass of two distinct sub-populations were 8.7 and 67.3 g AFDW m−2 yr−1 at Beach & Glacier and 20.0 and 88.6 g AFDW m−2 yr−1 at Punta Elefante. The following P / B values were calculated; Beach & Glacier = 0.129, Punta Elefante = 0.226. It is suggested that these differences are linked to mortality caused by icebergs which is expected to be higher at the shallower Punta Elefante site.

Six abandoned colonies of Adélie penguin (Pygoscelis adeliae) were excavated near Palmer Station, Anvers Island, Antarctic Peninsula, to investigate the occupation history of this species. Sediments from each site yielded abundant fish bones and otoliths and squid beaks that represent prey remains deposited by penguins during the nesting period. Radiocarbon analyses indicate that colony occupation began prior to the Little Ice Age (LIA; 1500–1850 AD), with the oldest site dating to 644 yrs before present (BP; average reservoir-corrected date with Is range, 603–679 yr BP). Food remains indicate that the non-euphausiid prey of penguins consisted primarily of a mesopelagic squid (Psychroteuthis glacialis) and two species of fish (Pleuragramma antarcticun and Electrona antarctica). The relative abundance of the first two prey taxa varied significantly among six sites (X2>34.6; df = 10; P <0.001) with colonies dating prior to the LIA having greater representation of squid, and less of silverfish, than those occupied during the LIA. Data from control excavations at three modern colonies indicate a diet similar to that of the pre-LIA sites. These results suggest that Adélie penguins may have changed their diet in response to warming and cooling cycles in the past. In addition, only Adélie penguins are known to have nested in the Palmer Station area prior to the l950s; gentoo (Pygoscelis papua) and chinstrap (P. antarctica) penguins now breeding in this region have expanded their ranges southward in the Peninsula within the past 50 yrs, in correlation with pronounced regional warming.

Oxygen microelectrodes were used to measure the photosynthetic rates of Antarctic fast ice algal mats. Using the oxygen flux across the diffusive boundary layer below the fast ice at Davis, a productivity range of 0–1.78 mg C m−2 h−1 was measured. This is at the lower end of fast ice productivity estimates and suggests that conventional 14C techniques may overestimate sea ice algal mat productivity. Photosynthetic capacity (P max) approached 0.05 mg C. (mg chl a)−1 h −1. Onset of photosynthesis saturation, E k, was found at c. 14 μmol photons m −2 s −1. The irradiance of photoinhibition onset, E inh, was c. 20 μmol photons m −2 s −1 and the irradiance at the compensation point, E c, was 4 μmol photons m −2 s −1.

Eight hundred photosynthesis-irradiance relationships were determined in the shelf waters adjacent to Palmer Station, Antarctica during the spring/summer periods of 1991–94. Biomass specific maximum photosynthetic rate, PBmax, and the light limited photosynthetic efficiency, αB, were poorly correlated to the physical forcing and nutrient regimes at the sampling stations. The two photosynthetic parameters, however, did strongly covary indicating the minimum irradiance required to saturate photosynthesis, Ik, was relatively constant in this highly variable environment. The variability in Ik could partially be attributed to both depth in the water column and time of the year, with the highest values occurring for surface samples during the summer period of peak incident irradiance. Given this and the significant dependence of Pmax on phytoplankton biomass, a simple empirical model for primary productivity was developed. An independent test of the model was performed on data collected in a mesoscale offshore grid and predicted primary production was found to be within 13% of measured values. Although there are limitations to this approach (i.e. exclusion of diel periodicity in photosynthetic response), these results provide relatively robust estimates of daily primary production for the Southern Ocean.

Gobionotothen gibberifrons <1 year old, of the 1977, 1980, 1981, 1985, 1986, 1990 and 1995 cohorts, were sampled using nets, in various periods during summer (December to February) at South Georgia. Growth in standard length (Ls) was estimated using the exponential model. Among the seven cohorts, average growth rate varied between 0.33–2.1% Lsd−1, and predicted Ls for mid-January varied between 21.6–29.1 mm. Average growth rate was inversely related to mean date of sampling but was not significantly related to mean Ls. Mean sea surface temperatures were available for the 1981–95 cohorts. Average growth rate and predicted Ls for mid-January were both negatively conelated with mean December–January sea temperature, but were not significantly related to mean weekly sea surface temperature during the sampling periods. Greater average growth rate and greater Ls in cooler summers may be partly due to a large-scale pattern of environmental variability, indicated by sea temperature, that governs the timing and magnitude of the production cycle and food availability.

Two gravity cores, Gebra-1 and Gebra-2 from the central and eastern basins of Bransfield Strait, West Antarctica, consist mainly of hemipelagic, laminated muds with black layers rich in sand-sized volcanic ash. Micropalaeontological (diatoms and radiolarians) and geochemical (organic and inorganic) analyses, together with radiometric dating (U/Th, 14C and 210Pb) have been performed on both cores. AMS analyses on Total Organic Carbon yielded a 14C-age older than expected, 2810 yr BP for the core top of Gebra-1 and 2596 yr BP for Gebra-2. The downcore pattern of ages indicates a sedimentation rate of 130 cm kyr1 for Gebra-1 and 160 cm kyr1 for Gebra-2 210Pb anomalies suggest the core top of Gebra-1 is present-day sediment. The diatom and radiolarian assemblages are related to the sequence of neoglacial events over the last three millennia. The recent significant reduction in Chaetoceros resting spores is interpreted as a reduction in palaeoproductivity. The progressive increase in sea-ice taxa for the last three millennia may indicate a cooling trend. Greater sea-ice coverage during the coldest neoglacial events in the Bransfield Basin, as well as in the Weddell Sea and Bellingshausen Sea, is documented by increases in sea-ice taxa and reductions in Thalassiosira antarctica/ T. scotia resting spores, Fragilariopsis kerguelensis, the Lithomelissa group and the “circumpolar” group of radiolarians. For these periods, we postulate a restricted communication between the Weddell Sea, Bellingshausen Sea and Bransfield basin. The millenial-scale changes are overprinted by a high frequency cyclicity at about 200–300 yrs, which might be related to the 200–yrs solar cycle.

Antarctic late Cenozoic pectinid-bearing sedimentary strata are chiefly confined to localities in the northern part of the Antarctic Peninsula, in the McMurdo Sound area, and Marine Plain, East Antarctica. Ages of these deposits range from Oligocene to Holocene. Chlamys-like scallops, which are absent from today's Southern Ocean, thrived in Antarctic waters during both glacial and interglacial episodes, but disappeared during the Late Pliocene. Their extinction is believed to result from the combined effects of increased carbonate solubility, habitat loss and limitations in food availability, associated with major cooling.

The diet of Cygnodraco mawsoni Waite 1916 and Gymnodraco acuticeps Boulenger 1902 (Pisces: Bathydraconidae) was studied in the Cooperation and Cosmonaut seas in the depth range 200–400 m during the summer 1988. Stomach content analysis showed that both species are piscivorous predators but with different feeding habits. Cygnodraco mawsoni fed mostly on young notothenioid fish, regularly complementing these with pelagic, Euphausia superba, and benthic crustaceans, such as amphipod gammarids and mysids. In contrast, G. acuticeps relied mostly on mesopelagic fish of the family Myctophidae. Although C. mawsoni and G. acuticeps occupy similar depths in the Cosmonaut Sea, different feeding habits appear to limit the probability of interspecific competition for food.

On the continental rise west of the Antarctic Peninsula there are nine large mounds interpreted as sediment drifts, separated by turbidity current channels. Drift 7 is 150 km long, 70 km wide and up to 700 m high and is asymmetric, with steep sides on the south-east (towards the continent) and south-west, and gentle slopes to north-west and north-east. Cores on the gentle sides of the drift show a cyclicity between brown, bioturbated, diatom-bearing mud with foraminifera and radiolarians, and grey, laminated, barren mud. Biostratigraphic evidence is consistent with a Late Quatermary age. Detailed lithostratigraphy and magnetic susceptibility data allow precise correlation over distances of tens of kilometres. On the basis of chemostratigraphy, the brown sediment is interpreted as interglacial (isotope stages 1 and 5) and the grey as glacial (stages 2–4 and 6). Sedimentation rates are 3.0–5.5 cm ka-1. Cores on the steep sides of the drift recovered a condensed section with thinner cycles and hiatuses. Fine grain size, very poor sorting and the absence of a mode in the silt size range indicate deposition from suspension with only weak current activity. There is little evidence for cyclic changes in bottom current strength. Supply of sediment to the benthic nepheloid layer was by entrainment of mud from turbidity currents, and by setting of pelagic material (biogenic grains, IRD, sediment suspended in meltwater plumes). Cyclic changes in sediment supply include more biogenic supply in interglacials with less sea ice cover, more terrigenous supply from turbidites in glacials with ice sheets grounded to the shelf edge, and changes in IRD content

A detailed study was made of the extent of genetic variation within populations of two moss species, Bryum argenteum and Hennediella heimii, from the Garwood Valley in Southern Victoria Land, Antarctica. RAPD (Random Amplified Polymorphic DNA) technology was used to analyse over 30 clumps of each species, collected from adjacent sites in five small meltstream drainage channels. Overall, extensive genetic variation was found, with no two samples being identical in either species. For both species, most clumps showed within-clump variation, although generally the shoots from each clump were most closely related to other shoots from that clump, indicating somatic mutation. Of the B. argenteum isolates, most showed distinct clustering corresponding to the five drainage channels, with some clustering within the top, middle or bottom of the channels, and separation of northern and southern sides of the valley. There was some evidence of across-channel dispersal for B. argenteum. For H. heimii, the situation was quite different; there was very little clustering of clumps according to channel from which they were collected. Rather, the isolates appeared to form one continuous population across the five channels, with partial separation of northern and southern sides of the valley. These results are consistent with the predicted means of dispersal of these species in Antarctica: predominantly by water for B. argenteum, and by wind for H. heimii.

Laser-based Fourier-Transform Raman spectroscopy (FTRS) has been used to identify in situ compounds of ecophysiological significance in diverse field-fresh Antarctic cryptoendolithic microbial communities. FTRS does not disrupt the community and permits characterization of visible and invisible compounds in their natural configuration within cells and their current or former microhabitat. The small “footprint” of the microscopic laser beam permits accurate analysis of discrete zones of compounds produced by extant or degraded micro-organisms with minimum destruction of the biota. This spatial chemical analysis is applicable to any translucent or exposed habitat or biotic assemblage. Two hydrated forms of biodegradative calcium oxalate were differentiated in black-pigmented and hyaline lichen zones of endolithic communities. The oxalate was restricted to zones containing fungi. Communities dominated by cyanobacteria at Battleship Promontory (77°S) and a newly discovered site at Timber Peak (74°S) contrasted chemically with those dominated by eukaryotic algae at East Beacon (78°S). FTRS also showed the zonation of pigments including chlorophyll and UV-protective carotenoids in situ. At extreme sites on the polar plateau, it revealed the presence of “fossil” endolithics where detrimental climatic changes had made the microbes non-viable or amorphous, being represented solely by their residual bio-molecules. The technique has potential for past or present life-detection anywhere in the world without destruction of the microniche.

Erosion of bedrock from lower intertidal reefs by waves acting on attached plants of bull-kelp (Durvillaea antarctica) was investigated over one year at Macquarie Island, Southern Ocean. At a site on the more sheltered east coast, such erosion occurred during four separate storms, each casting up 834–1078 large kelp plants km−1 of coast, of which 30–45% were still attached to jagged, freshly quarried bedrock fragments over 2.5 cm long. The largest fragment weighed was 74.6 kg; rounded cobbles and boulders attached to kelp plants and weighing up to 102.2 kg (and probably more than 160 kg) were also cast up on beaches. 19–21% of the standing crop of large kelp plants was removed by storms during the year of observation. Break points for 10 kelp stipes were found to be at least 90–161 kg. Total annual erosion by kelp-plucking is at least 1.56 tonnes of rock km−1 of coast. However, in terms of erosion this computes to only 0.1 mm yr−1, far below the rate of uplift of the island.

The Weddell Sea region arguably represents the largest unknown in quantifying the Antarctic contribution to the global water balance following the Last Glacial Maximum (LGM). This paper reviews the available onshore and offshore geological evidence constraining the volume of formerly expanded ice in the Weddell Sea embayment, focusing on the West Antarctic Ice Sheet (WAIS) and provides a preliminary reconstruction of the WAIS during the LGM. Dating control is generally poor and so our WAIS reconstruction is based on the assumption that the evidence of most recent ice sheet expansion dates to the LGM. Our reconstruction is intended to provide initial constraints with which glaciological models can be compared and shows grounded ice extent, flow directions, and ice surface elevations. Both marine and terrestrial geological evidence imply a substantial expansion of ice in the Weddell Sea embayment. Marine evidence shows that ice sheets were grounded in Crary Trough in the southern Weddell Sea and on the Antarctic Peninsula continental shelf during the LGM. Inland, the ice thickened by between 400 m (Ellsworth and Palmer Land) and 1900 m (Ellsworth Mountains). Ice core evidence suggests that the interior of the ice sheet remained the same or even thinned relative to present. The main unknowns now concern the exact location of the grounding line on some sectors of the shelf and the timing of ice sheet grounding and retreat. The limited radiocarbon data that exist on the eastern shelf indicates that the East Antarctic Ice Sheet retreated from the shelf prior to the LGM.

Seasonal haul-out patterns and diet of individually marked leopard seals (Hydrurga leptonyx) were investigated at Bird Island, South Georgia during the 1983–96 winters. A total of 2956 leopard seal sightings were made, and 121 seals were tagged during the study, mainly between 1993 and 1996. Photographs of scars and pelage patterns were also used to identify a subset of these individuals across years, which provided no evidence of tag loss between or within years. Leopard seals were observed between April and November; the mean time between the first and last sightings in each year was 208 d (s d ± 48). Between 1993–96, eight seals were resident around the island for more than 100 d, and the longest recorded residence was 130 d. The proportion of tagged seals resighted was 0.35 and 0.17 in 1995 and 1996 respectively. Based on estimates of body length, <5% of the seals were juveniles (0–1 years) and >70% were not sexually mature. There was considerable inter-annual variation in abundance, with a maximum of 502 sightings during 1994, compared with a minimum of 21 during 1986 and 1989. Antarctic fur seals (Arctocephalus gazella) were the main prey item (58% of kills observed and 53% of scats). Other items included penguins (28% of kills observed and 20% of scats) and fish (24% of scats). Antarctic krill (Euphausia superba), southern elephant seals (Mirounga leonina) and seabirds other than penguins were also present in the diet in small quantities.

We studied the influence of the semi-annual oscillation (SAO) on near-surface temperatures in Antarctica, using observations of 27 stations that were operational during (part of) the period 1957–79. For the annual cycle of surface pressure, the second harmonic explains 17–36% of the total variance on the Antarctic Plateau, 36–68% along the East Antarctic coast and almost 80% on the west coast of the Peninsula, and decreases further to the north. As a result of the amplification of the wave-3 structure of the circulation around Antarctica, a significant modification of the seasonal cooling is observed at many stations. The magnitude of this modification is largely determined by the strength of the temperature inversion at the surface: the percentage of the variance explained by the second harmonic of the annual temperature cycle is then largest on the Antarctic Plateau (11–18%), followed by the large ice shelves and coastal East Antarctica (6–12%) and stations at or close to the Peninsula (0–5%). A significant coupling between the half-yearly wave in surface pressure and that in surface temperature is found for coastal East Antarctica, which can be directly explained by the changes in meridional circulation brought about by the SAO. We show that the coupling of Antarctic temperatures to the meridional circulation is not only valid on the seasonal time scale of the SAO, but probably also on daily and interannual time scales. This has important implications for the interpretation of time series of Antarctic temperatures, a problem that will be addressed in part 2 of this paper.

This overview examines available circum-Antarctic glacial history archives on land, related to developments after the Last Glacial Maximum (LGM). It considers the glacial-stratigraphic and morphologic records and also biostratigraphical information from moss banks, lake sediments and penguin rookeries, with some reference to relevant glacial marine records. It is concluded that Holocene environmental development in Antarctica differed from that in the Northern Hemisphere. The initial deglaciation of the shelf areas surrounding Antarctica took place before 10 000 14C yrs before present(BP), and was controlled by rising global sea level. This was followed by the deglaciation of some presently ice-free inner shelf and land areas between 10 000 and 8000 yr BP. Continued deglaciation occurred gradually between 8000 yr BP and 5000 yr BP. Mid-Holocene glacial readvances are recorded from various sites around Antarctica. There are strong indications of a circum-Antarctic climate warmer than today 4700–2000 yr BP. The best dated records from the Antarctic Peninsula and coastal Victoria Land suggest climatic optimums there from 4000–3000 yr BP and 3600–2600 yr BP, respectively. Thereafter Neoglacial readvances are recorded. Relatively limited glacial expansions in Antarctica during the past few hundred years correlate with the Little Ice Age in the Northern Hemisphere.

Lithium distributions in lake and pond waters of the McMurdo Dry Valleys of southern Victoria Land, Antarctica were studied to elucidate the origin of dissolved salts and the evolutionary history of the lakes and ponds. The EfLi [(Li/Cl)sample/(Li/Cl)seawater] values of the bottom waters in Lakes Bonney and Fryxell were higher than unity (EfLi=4–7), indicating that the salts originated from sea salts (probably relict seawater) and have been subsequently modified by the contribution of meltwaters containing atmospheric fallout and/or rock and soil weathering products. In contrast, extremely high Li concentrations with high EfLi values in the Don Juan Pond water (EfLi = 180) and the bottom waters of Lake Vanda (EfLi = 40) suggest that the salts originated from deep groundwaters influenced mainly by saline water-rock interactions, as supported by the dissolution experiments of granite in NaCl solution. The low Li concentrations of pond waters with high EfLi values in the Labyrinth indicate that the salts are derived from atmospheric fallout. The decrease of the EfLi values with the increase of Cl concentrations can be explained by the repeated cycles of the migration of Li into the ice phase and subsequent ablation of surface ice, as indicated by seawater freezing experiments.