The dense phytoplankton blooms observed in earlier studies in the Southern Ocean Marginal Ice Zone (MIZ) may not be representative of all regions, so that some previous assessments of the overall importance of this system in total primary production may have been overestimated. Recent observations have shown that increased phytoplankton production may not always be associated with the retreating ice-edge, due to the unpredictability of meltwater-induced stability. Complex interactions between the MIZ and hydrographic fronts have also been indicated. A range of simple simulations, based on biomass inventories for the major biogeochemical systems in the Southern Ocean, show that the greater part of chlorophyll biomass is located in the extensive regions between the major fronts. Consideration of the fronts and the MIZ only, which we surmize may be the principal sites of export production, indicates that the MIZ is clearly the most important single feature. Even if the occurrence of MIZ blooms in the simulations is reduced dramatically, such blooms still appear to make a substantial contribution to production and, by implication, carbon export.

Biomass allocation and growth by the clonal plant Acaena magellanica were characterized for three populations grazed by introduced reindeer on the subantarctic island of South Georgia. Annual growth markers (internode lengths) were used to divide each rhizome into current year's shoots, one-year-old and two-year-old rhizome segments. Total dry weights were significantly smaller in grazed than in ungrazed populations. Leaf biomass of current year's shoots was very much lower in grazed shoots. Rhizome length and number of leaves were less affected than dry weight by grazing, and the reindeer grazing thus seems to mainly influence biomass accumulation rather than morphology in Acaena. Interactions with Festuca contracta in both grazed and ungrazed areas were also studied in a two-year competition experiment. No apparent release of soil resources (as measured by an increase in plant growth) was apparent in plots where Festuca was removed, but the current year's shoots of Acaena were smaller and more numerous in these plots than in controls, especially in the ungrazed area.

In 1991 Chamsocephalus gunnari <1 year old were sampled at Shag Rocks on 18 January and off five bays on the north-east coast of South Georgia between 19 January and 12 February. Two separate size-groups of 31–46 mm and 55–87mm standard length (SL) were found at Shag Rocks. However, samples taken off Possession Bay, South Georgia, within two days of those at Shag Rocks, contained only one size-group of 25–57 mm SL. Samples taken at other locations at South Georgia also contained only single size-groups between 24–63 mm SL. The mean and median length of the large size-group at Shag Rocks are significantly larger (P<0.001) than those at South Georgia. For those at South Georgia there was an apparent growth of around 0.76% SL d−1, which is comparable with previous reports of their growth rate during the first year. Based on this growth rate, the differences between the average size of the larger size-group of C. gunnari at Shag Rocks and those at South Georgia indicates that they hatched at periods separated by about three months. This and other published evidence suggests there may be separate populations of C. gunnari at Shag Rocks and South Georgia.

The vertical distribution, abundance, population structure and life cycle of the ice-associated copepod, Paralabidocera antarctica was studied in the fast ice near Syowa Station (69°00'S, 39°35'E) in the eastern part of Lützow-Holm Bay in 1970, 1975 and 1982. The results indicated that P. antarctica inhabited the ice-seawater interface throughout the year with a one year life cycle and was actually present in the sea ice for most of the year except the summer. P. antarctica overwintered as naupliar stages (NIV-NV) with slow development in sea ice during winter. P. antarctica population then developed rapidly and attained adulthood in the water just beneath the sea ice during spring-summer. P. antarctica depended entirely on ice algae for food throughout its whole life-span, suggesting that the ice-seawater interface provides favourable food conditions for P. antarctica. The slow development in naupliar stages in sea ice and short copepodite life span in the water suggest that P. antarctica may adapt its growth strategy to suit the varying fast ice/water interface environment.

Modern diatom samples were collected from 43 sites across the Strømness Bay area of South Georgia. From 115 taxa belonging to 22 six diatom assemblages were distinguished. A CCA-analysis indicated that the assemblages are linked to pH and conductivity ranges, and habitat structure. The Eunotia paludosa var. paludosa - Eunotia subarcuatoides assemblage occurs in small acid water bodies. Samples of the Fragilaria germainii - Pinnularia aff. anglica assemblage are found in pools with a relatively high conductivity. The Fragilaria neoproducta assemblage and the Achnanthes subatomoides - Navicula vitabunda assemblage are mainly found in larger pools and lakes. This relationship between the assemblages and pH was comparable with results found in the testate amoebae fauna of South Georgia.

During winter research cruises to South Georgia (1983 and 1993) fish eggs were abundant in the neuston. Examination of the external sculpturing and the micropyle morphology of the eggs collected during 1993 using scanning electron microscopy indicated that these were fertilized ova of Notothenia rossii marmorata. A comparison between the eggs of N. rossii from Iles Kerguelen and South Georgia showed these to have a similar surface morphology but a difference in the structure of the micropyle. In 1993, the abundance of fish eggs in the neuston varied from 0-116 eggs m−3 with an average of 4.5 eggs m−3. During 1983, eggs were most abundant in the neuston but at lower average levels (0.04 eggs m−3, range 0–1.17 eggs m−3) and these were distributed from the surface to >380 m.

The food and energy requirements of adult emperor penguins parenting chicks were examined at Auster (about 11 000 pairs) and Taylor Glacier (about 2900 pairs) colonies during the winter, spring and summer of 1988. Tritiated water-derived estimates of food consumption trebled during the five-month period of chick care, ranging from 2.3 kg d−1 in winter when chicks were <5% of adult mass, to 6.3 kg d−1 in summer, when chicks represented 40–50% of adult mass. These food consumption rates were equivalent to the acquisition of 11.4 MJ d−1 and 33.4 MJ d−1 metabolizable energy in winter and summer respectively. Chick provisioning was not accompanied by a major increase in food consumption by adults. Adults assimilated 84–92% of their daily food intake themselves and retained the remainder for the chick. The food ration of chick for the three seasons (42 kg) constituted only about 9.5% of adult maintenance requirements during the same period. Adults consumed an estimated 482 kg of food (including the ration for the chick), which amounted to about 10 700 t and 2800 t of fish and squid consumed by the breeding populations at Auster and Taylor Glacier, respectively.

The occurrence of fish in the diet of the Antarctic fur seal (Arctocephalus gazella) at Bird Island, South Georgia was investigated by analysis of fish otoliths in scats (faeces) collected during late May to early November 1983. Of the 55 scats examined, 49 contained fish remains, and 45 contained fish otoliths. Ten fish species were represented by 415 otoliths, and 33 otoliths were too digested to be identified unequivocally. Fish size was estimated from otolith size based on published allometric equations. Four coastal notothenioid fishes dominated the fish component of the diet: Champsocephalus gunnari and Gobionotothen gibberifrons each comprised about 40% of the total fish mass; Chaenocephalus aceratus was ranked third by mass and the smaller Lepidonotothen larseni occurred in one quarter of the scats but was of lower importance in terms of mass. The length-frequency distribution of C. gunnari landed by the commercial fishery in October 1982 to June 1983 is similar to that which comprised the bulk of the diet in the present study. Compared with recent studies on the fish component of the diet in the literature, the dominance of C. gunnari is generally similar, however, there was a greater proportion of G. gibberifrons during the 1983 winter and spring than reported for recent winters.

Closely spaced continuous temperature profiles from expendable bathythermographs launched along two sections across the Drake Passage and western Scotia Sea in the summer 1981–1982 are used to examine the vertical medium-scale (∼10–100 m) temperature fine structure. The large-scale temperature structure across the frontal regimes characteristic of the Antarctic Circumpolar Current and the cross-frontal structure of the upper ocean are discussed. In the Drake Passage the heat content drops about 0.5 × 102 Kcal cm−2 (2 × 109 J m−2) across the Subantarctic Zone and 0.9 × 102 Kcal cm−2 (3.6 − 109 J m−2) across the Polar Front. In the Scotia Sea the heat content changes across the front are not as prominent. The statistical model of Joyce (1977) is used to quantify the heat fluxes across the fronts produced by the medium-scale temperature interleaving. In the Drake Passage the estimated heat flux is 0.32 × 10−3 °C m s−1 (1.3 × 103 W m−2) across the Subantarctic Front and 0.46 × 10−3 °C m s−1 (1.9 × 103 W m−2) across the Polar Front. In the Scotia Sea the estimated heat flux is larger in the Polar Front reaching 0.71 × 10−3 °C m s−1 (2.9 × 103 W m−2). The medium-scale fine structure heat fluxes are about 10% of the existing estimates of the mesoscale eddy heat fluxes and comparable to heat fluxes associated with the meridional flow of deep and bottom waters across the Antarctic Circumpolar Current.

Temporal and spatial variations of the epilithic phycoflora were studied in one of the largest streams at Hope Bay (Antarctic Peninsula) during the summer of 1992/93. A complete floristic inventory was made, and the relative frequencies of each algal taxon were estimated. Periphytic cumulative chlorophyll a was measured by means of artificial substrata. The stream was a typical maritime Antarctic lotic ecosystem, with evident signs of enrichment by sea-birds. Variability in discharge strongly affected the water chemistry, with the high water level periods characterized by the lowest conductivities and dissolved reactive phosphorus concentrations. Epilithic algal communities predominantly consisted of algal mats or filamentous and foliose forms of Prasiola crispa. Other dominant species were Leptolyngbya fragilis, Hydrurus foetidus, Chrysococcus cf. rufescens and Phaeogloea mucosa. Whereas P. crispa appeared more frequently near to the origin of the stream in Boeckella Lake, Chrysophyceae were better developed towards the mouth.

During January 1994 seven meltwater ponds on the McMurdo Ice Shelf were investigated for their content of biogenic iodinated and brominated volatile hydrocarbons. An efficient purge and trap system in combination with a powerful gas chromatographic separation and an electron capture detector achieved detection limits of 0.02–0.4 ng 1−1, depending on the different substances. The following compounds could be identified and quantified: CH3I, CH2I2, CH2C1I, CHBr3, CH2Br2, BrCH2CH2Br, CHBr2Cl, and CHBrCl2. This is the first time that 1,2–dibromoethane has been detected as a biogenic substance in the environment. In contrast to many other aquatic systems, where CH3I is found to be the most volatile iodine compound, CH2I2 showed the highest concentration in all ponds falling in the range of 5–20 ng 1−1. In three of seven ponds investigated, CH2CII was the second abundant iodinated substance. CHBr3 usually exhibited concentrations in the range of 2.5–8.6 ng 1−1. BrCH2CH2Br, previously not observed as a biogenic compound, was found to have concentrations similar to those of bromoform and even exceeded the bromoform content in two ponds and the CH2Br2 content in all ponds. Whether cyanobacteria, the dominant organisms in the ponds, are responsible for this distribution pattern must be clarified by further investigations.

An examination of notothenioid fish of three species, including 23 immature Notothenia coriiceps Richardson, revealed seven acanthocephalan species, including two Echinorhynchida occurring in the intestine and five Polymorphida in the body cavity. Four species -Metacanthocephalus johnstoni Zdzitowiecki, Corynosoma arctocephali Zdzitowiecki, C. pseudohamanni Zdzitowiecki, C. shackletoni Zdzitowiecki - are reported for the first time from the area. Polymorphida were twice as numerous as Echinorhynchida. The dominant parasites were Aspersentis megarhynchus (Linstow) and C. hamanni (Linstow) in Notothenia coriiceps, and C. bullosum (Linstow) in Chaenocephalus aceratus (Lönnberg). The infection of Notothenia coriiceps and Chaenocephalus aceratus in this area was compared with these species and Notothenia rossii Richardson in neighbouring areas. The infection of Notothenia coriiceps at the South Orkney Islands is more similar to that at the South Shetland Islands than that found at South Georgia.

Freshwater drainage systems, fed by melting of nearby inland ice and perennial snowdrifts, exist in the south-eastern part of arid, ice-free, coastal Vestfold Hills. Most important is the complex Druzhby system. Intriguing questions arise about the conditions controlling its seasonal development and about the consequences of possible changes of those conditions. A water-balance was calculated for 1990–91. The system went through four seasonal phases of which only one displayed a fully developed external drainage. Evidently, the relative duration of those phases can vary considerably from one year to another. The system depends critically on the water supply from ice-dammed Chelnok Lake, which could readily be drained by a minor retreat of Sørsdal Glacier. Exposed to excessive evaporation, the large Crooked Lake would then become internally drained and reach a new equilibrium in ∼830 years. A Crooked Lake sediment core can be interpreted as suggesting this occurred during the Holocene. The idea, inferred from striae, of a late Holocene Chelnok Glaciation reaching the northern shores of Crooked Lake is questioned. Instead, it is suggested that the Chelnok striae originate from local basal melting of the ice sheet draining southward into a deglaciated Sørsdal trough. At present, runoff is determined by opposing short and long-term climatic influences.

Six new species of marine Enchytraeidae, Grania hirsuticauda sp.n., G. acanthochaeta sp.n., G. carchinii sp.n., G. angustinasus sp.n., G. antarctica sp.n. and G. algida sp.n., are described from benthic material collected in McMurdo Sound during 1959–61 and Terra Nova Bay in 1988. They represent the first records of this family from below the Antarctic circle and, together with tubificids, the first oligochaetes from the Ross Sea. G. hirsuticauda, apparently the most widespread species in McMurdo Sound, is distinguished by having setae abruptly larger in the posterior third of the body and almost nodulate; a T-shaped prostomial bifurcation of the dorsal vessel, short sperm funnels and sperm sac, and thick-walled spermathecae. G. acanthochaeta possesses a unique, thorn-like, setal morphology and diverticulate spermathecal ampullae. G. carchinii, the only new species lacking lateral setae, is also distinguished by a remarkably high development of the chloragogen tissue and the possession of nephridia at 6/7. G. angustinasus, the most abundant species in the sampling area in Terra Nova Bay, and G. antarctica, have the same setal distribution, size and (curved) shape, but show different forms of penial bulbs (more complex in G. angustinasus) and spermathecal structures (the ampullae being larger and the external pores more posterior in G. antarctica). G. algida is distinguished by its L-shaped setae and carrot-shaped, diverticulate, spermathecal ampullae. All the new species lack cuticular penial stylets as well as spermathecal ectal glands. All species but G. carchinii are peculiar in possessing, in front of the brain, a middorsal vesicular body of specific shape and size containing a few refractile inclusions; a sensory (possibly a statocyst-like) function is suggested for this ‘head organ’, which has not been previously reported in the Oligochaeta.

Lake Wilson, a perennially ice-capped, deep (>100 m) lake at 80°S in southern Victoria Land was investigated in January 1993. Water chemistry and physical structure showed three distinct layers; an upper c. 35 m mixed layer of low salinity, moderately turbid water; a less turbid mid layer, 20 m thick of slightly higher salinity and supersaturated with oxygen; and a deep 20 m brackish layer (conductivity c. 4000 μS cm−1) with anoxic conditions in the lower 5 m. Extreme supersaturation of N2O (up to 400 times air saturation) together with high nitrate concentration (4000 mg m−3) was recorded in the deep layer. Phytoplankton biomass and photosynthetic activity was confined to the upper mixed layer and the band of supersaturated dissolved oxygen located at 40–55 m appears to represent a relict layer from when the lake level was lower. The evidence from a comparison of profiles between 1975 and 1993 suggests that Lake Wilson has risen 25 m since 1975, synchronous with a period of lake level rise in the McMurdo Dry Valleys lakes to the north at 77°S. Geochemical diffusion models indicate that Lake Wilson had evaporated to a smaller brine lake about 1000 yrs BP, which also fits the pattern shown by the McMurdo Dry Valleys lakes. Climate changes influencing lake levels have thus covered a wide area of southern Victoria Land.

Well-preserved eclogites were found for the first time in Antarctica, at the Lanterman Range, northern Victoria Land. They are part of a mafic–ultramafic belt that lies between the Wilson Terrane, representing part of the palaeo-Pacific margin of Gondwana, and the Bowers Terrane, a Cambro-Ordovician volcanic are and related sediments, accreted to the margin during the Ross Orogeny. The eclogites formed at temperatures in the range 750–850°C and pressures above 15 kbar and subsequently experienced a decompressional path to low pressure amphibolite facies conditions. The formation and exhumation of eclogites and the attainment of the metamorphic peak in adjacent rock units is consistent with a plate convergent setting model at the palaeo-Pacific margin of Gondwana.

The stratigraphy of the upper part of the Upper Palaeozoic–Lower Mesozoic Victoria Group in the central Transantarctic Mountains is reviewed. Marked lithologic contrasts exist in the Falla Formation between the lower volcanic-poor part and the upper volcaniclastic part. The name Falla Formation is here restricted to the lower volcanic-poor part of the sequence making it the youngest formation in the Victoria Group. The upper volcaniclastic part, a tuffaceous sequence, is named the Hanson Formation.

The Tertiary stocks (Meander Intrusives) cropping out along the coasts of the Ross Sea were sampled for a palaeomagnetic study during the sixth Italian expedition to northern Victoria Land. Laboratory investigations concerned magnetic mineralogy and remanent magnetization. Minerals of the magnetiteulvöspinel series occur in the rocks from all stocks, with low-Ti titanomagnetite usually prevalent. Haematite and goethite occur in small amounts as alteration products. Large secondary components commonly screen the characteristic remanent magnetization and were removed by thermal or AF demagnetization at temperatures or peak-fields higher than 360°C and 20 mT respectively. A total of 10 VGPs were obtained from radiometrically dated rocks (42–22 Ma); the averaged position (69°S, 334°E; α95=9.9°) is the first middle Tertiary palaeomagnetic pole for East Antarctica, and gives evidence for a reversal in the course of the APW path. This evidence is not substantially altered by a supposed tilt-correction consistent with geophysical and geological models for the uplift of the Transantarctic Mountains. No definite conclusion about relative movements between East Antarctica and the Antarctic Peninsula can be drawn from the existing palaeomagnetic data.

An extensive analogue database of 60 MHz radio-echo sounding records of Antarctica (covering 50% of the ice sheet) is held at the Scott Polar Research Institute, University of Cambridge. This database was analysed in order to determine the presence and location of Antarctic sub-glacial lakes. In total, 77 sub-glacial lake-type records were identified, 13 more than detected in previous studies. An inventory of these sub-glacial lakes includes geographical coordinates, minimum length and overlying ice thickness for each lake. Information concerning the location of these lakes indicates that the majority (~70%) are found in the proximity of ice divides at Dome C and Ridge B within East Antarctica.

Reproductive characteristics are compared of the nototheniids Trematomus bernacchii and T. hansoni and the channichthyid Chionodraco hamatus caught in summer at Terra Nova Bay (Ross Sea) and caught all the year round in the waters off Casey Station (Mawson Sea). Whilst spawning of T. bernacchii took place in October–November off Casey and probably at Terra Nova Bay, the spawning period of T. hansoni differed between the sites (September–November off Casey, December–February at Terra Nova Bay). The spawning period also differed between sites for C. hamatus (August–October off Casey, December–February at Terra Nova Bay). Fecundity was higher and egg size was lower in nototheniid species (c, 8000 eggs of 3–4 mm) than in channichthyid (c. 4000 eggs of 4–5 mm). Moreover, the fecundity was lower and egg size higher in the specimens from Terra Nova Bay when compared to Casey.