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The biota and environment of fumarolic ground recently discovered near Mount Rittmann are described. Three patches (about 1 m2 each) of the moss Pohlia nutans were found in a minor caldera rim. Cyanophytes, chlorophytes, protozoa and bacteria were isolated from the moss and warm ground (30–50°C). The results are compared with those of previous studies on Antarctic volcanoes. The origin of the geothermal flora is discussed in terms of long-distance transport of propagules to the continent.

Reproductive allocation (reproductive biomass relative to vegetative biomass) and seed production were measured for samples of the two native phanerogams occurring in Antarctica. Material collected on South Georgia (subantarctic), Signy Island (northern maritime Antarctic) and Léonie Island (southern maritime Antarctic) allowed an initial comparison of reproduction over a wide latitudinal range. Sizes of vegetative and reproductive structures of Colobanthus quitensis were smaller in Signy Island samples than those from South Georgia or Léonie Island. This pattern was reflected in the pattern of seed production. Vegetative and reproductive structures of Deschampsia antarctica were generally similar in size at both maritime Antarctic sites, but larger at subantarctic South Georgia. Seed production was similar in each season assessed and at all three sites. In most samples of both species there were close relationships between reproductive and vegetative biomass, and seed output and reproductive biomass. Subantartic C. quitensis showed greater allocation to seed production than material from maritime Antarctic sites. D. antarctica showed the reverse pattern, with greater allocation to reproductive biomass and seed production in most samples of maritime Antarctic material, particularly those from Signy Island. Reproductive strategies do not form any specific adaptation to the Antarctic environment for these species. Reasons for the failure of other higher plants to become established in the maritime Antarctic are discussed, and it is concluded that geographical isolation is the main factor. The most important proximate factors influencing propagules which reach potential colonization sites are likely to be the short length and low temperature of the summer season in relation to the time required for establishment.

The fate of ice biota released via meltwater into pools of seawater trapped between melting ice floes (crack pools) was followed in late January in the southern Weddell Sea. Low salinity crack pools shared the following features: nitrate exhaustion, high pH and POC/PON ratios, high bacterial biomass composed of large cells, and a dense algal assemblage dominated to over 90% by only two diatom species. It is suggested that this “climax stage” evolved from a nutrient rich, moderate biomass situation prevailing in high salinity crack pools, and is representative of summer succession of sea ice biota. “Overflow” production following nitrate exhaustion by the algae resulted in internal (lipid) and external (presumably mucus) carbon pools. The latter must fuel bacterial biomass build-up, as algal mortality appeared to be low. The large algal and bacterial stocks point to low grazing pressure exerted by phagotrophic protists, presumably due to poor food quality (e.g. high C/N ratios) and/or excessive mucus production. It is concluded that environmental selection of the abundant ice algal species occurs under conditions prevailing in the disintegrating ice cover during summer, which differ drastically from those generally referred to as characteristic of the sea ice habitat at large (a combination of low temperature, low light and high salinity).

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.

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.

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.

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.

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.

At Mount Charity, north-eastern Palmer Land, Rb–Sr whole-rock dating has identified three successive phases of granitoid emplacement in Triassic (232 ± 4 Ma), Jurassic (168 ± 1 Ma), and Cretaceous (120 ± 4 Ma) times. The Triassic suite comprises tonalites, granodiorites (including one two-mica granodiorite), monzogranite and a granite having either I-type or S-like mineralogies. The Jurassic suite includes only S-like granites, and the Cretaceous biotite tonalites and biotite granodiorite are all I-type. The three suites have negative ∈Nd and positive ∈Sr, and have subtly different Nd and Sr isotope characteristics: Suite A, ∈Srt =+30 to +53 and ∈Ndt =−0.9 to −3.1, Suite B, ∈Srt =+43 to +64 and ∈Ndt =−2 to −5.3, Suite C, ∈Srt =+22 to +23 and ∈Ndt =−2.5 to −2.6. Mineralogical and compositional differences between the three suites suggest that different sources were tapped. All the granitoids are isotopically intermediate in composition between Palmer Land crust and depleted asthenosphere. We suggest that the I-type granitoids were produced by melting of meta-igneous crust; by contrast, the S-like granitoids represent partial melts of garnet-bearing sedimentary crust. Syn-magmatic structures in Suite A are compared with known structural events in western Palmer Land and suggest that extension controlled Triassic pluton emplacement. The Jurassic magmas were also emplaced during an episode of arc extension, and intrusion of the Cretaceous magmas was probably controlled by regional extension and dextral transtension. Successive phases of magmatism focussed at Mount Charity are consistent with reactivated faults acting as magma conduits.

Atmospheric surface pressures on the East Antarctic ice sheet are examined as a contribution to a new regional climatology based on automatic weather stations (AWS). Monthly mean pressures along two meridional AWS lines show near the coast a semi-annual oscillation with equinoctial minima, which become submerged inland under a larger annual oscillation, asymmetrically shaped around a summer solstice peak. Such a peak could arise when air surrounding the ice sheet is heated and enabled to spread out over the ice. This concept has provided a classical prediction of the ice sheet's mean elevation; in this paper the theory is expressed in a more modern form. After the summer “flood” the vertical tropospheric circulation driving the progressive katabatic surface layer drainage from the ice sheet should create relatively higher pressures below the convergence region over the ice sheet center and lower pressures near the coast. In fact the observed mean monthly surface pressures decrease with elevation more slowly than follows from substituting the observed mean temperature-elevation gradients (“topographical lapse rates”) in the hydrostatic equation. However, below the surface inversion along the sloping ice sheet surface the hydrostatic balance is shown to be governed by temperatures higher than observed at the surface. Hydrostatic pressures are calculated with climatic estimates of the inversion strength. Their differences from the observed monthly mean surface pressures represent non-hydrostatic residuals which can be added to pressures at the coast to form elevation-free (“sea level”) pressure profiles. These show both the expected coastal troughs and high pressure over an ice sheet summit (Dome C).