The last decade of Antarctic ecological research has seen a growing awareness of the pre-eminent role played by microscopic life-forms throughout this region of the biosphere. Yet despite much new information, fundamental questions remain about the species diversity and community structure of the Antarctic microflora. There are major deficiencies in our knowledge of all microbial groups, and the information base is especially inadequate for the ice-free and coastal regions increasingly subject to human impacts.

The structure and function of swimming muscles in Antarctic fish is reviewed, the emphasis being on the highly endemic sub-order Notothenioidei. Adult stages of the vast majority of species swim at low speeds using large pectoral fins (labriform locomotion). This is supplemented with sub-carangiform swimming in pelagic juvenile stages and in the adult stages of some other species. The thrust for sustained activity is provided by the recruitment of slow muscle fibres. Slow muscle myofibrils typically occur in columns one fibril thick entirely surrounded by mitochondria. The resulting high volume density of mitochondria (30–60%), and short inter-mitochondrial spacing, is thought to represent an adaptation which serves to compensate for the detrimental effects of low temperature on enzyme reaction and diffusion rates. Sub-carangiform swimming is used to achieve burst speeds associated with prey capture and/or predator avoidance. Burst speeds require the recruitment of fast twitch fibres in the myotomes. In many demersal species the energy supply for burst swimming largely comes from phosphogen hydrolysis, and the capacity of fast twitch fibres for anaerobic glycogenolysis is severely reduced. Antarctic fish are characterized by delayed maturation, slow growth and low metabolic rates. The fast myotomal muscles of adult stages often contain few fibres less than 80 μm diameter, fibres 200–450 μm diameter forming the major size class in numerous species. It is therefore likely that hyperplasia ceases at a relatively early stage in development and that subsequent muscle growth involves hypertrophy of existing fibres. Studies of the contractile properties of isolated muscle fibres suggest that low temperature limits maximum swimming performance in Antarctic fish. Kinematic data suggest that this is most noticeable for juvenile stages, which have higher maximum tail-beat frequencies than adults.

Specimens of Prasiola collected from habitats not experiencing nutrient enrichment from birds are considered to be P. calophylla. The alga has three distinct growth forms; uniseriate filaments, narrow ribbons and expanded sheets. Reproduction is by aplanospores and fragmentation of the thallus. The known Antarctic distribution is disjunct with only two records outside Victoria Land. However, it is widespread in the latter region. The alga is absent from areas where there are high salt concentrations in waters and soils. Elsewhere it is common in streams and on water-flushed ground as well as occurring on terminal ice-faces of glaciers and as chasmoendolithic growths. Ribbons are found mostly on the lower surfaces of stones, and uniseriate filaments on the exposed surfaces of the stream beds of seasonal melt streams. Expanded sheets occur in less vigorous water flows. There is a need for further culture and field studies in order to understand the factors which control morphological development and distribution patterns.

Following the break-up of Gondwana, the drift of Antarctica to its present position and the establishment of the Antarctic Convergence, fish evolution was characterized by adaptation to progressive cooling of the environment. The decrease of erythrocyte number and haemoglobin concentration in the blood of Antarctic teleosts raises several questions concerning the physiology of respiration and the enzymatic role of erythrocytes. Our study of the molecular basis of cold adaptation includes the relationship between molecular structure and biological function of haemoglobins. Species of the suborder Notothenioidei, largely confined within the Convergence, have only one major haemoglobin, which displays the Root effect in oxygen binding; on the other hand, Zoarcidae (a family found at all latitudes) have four or five haemoglobins, only one of which displays the Root effect. In addition, our data indicate that the physiological relevance of erythrocyte-like cells, present in very small number in the blood of haemoglobinless Channichthyidae, may be linked to higher content of enzymes, such as glucose-6-phosphate dehydrogenase, in comparison with erythrocytes of red-blooded fishes.

The extensive ablation zone on the McMurdo Ice Shelf (78°S, 165°30′E) contains numerous ponds that are lined with benthic mats of cyanobacteria and associated micro-organisms. The photoautotrophic biomass content of these mats was examined in six contrasting ponds. Particulate carbon contributed only 3.2% of the mat dry weight, with C:N ratios generally less than 20:1. The chlorophyll a content was low relative to carbon (chlorophylla : C<0.01). Analysis of the mats by high performance liquid chromatography [HPLC] showed that the pigment fraction assayed spectrophotometrically as chlorophyll a contained large quantities (up to 70%) of the degradation product chlorophyllide a and the epimer chlorophyll a'. Photosynthetic rates per unit chlorophyll a[HPLC] were extremely slow: <0.1 mg C (mg Chla)−1, less than one tenth the rates recorded in the overlying phytoplankton community. These analyses indicate that in the ice pond benthic mats most of the dry weight is inorganic, most of the organic carbon is non-chlorophyll-containing material, and much of the chlorophyll a is not photosynthetically active. Cold temperatures and the associated low activity of herbivores and detritivores may contribute towards this preservation of inactive chlorophyll a on the McMurdo Ice Shelf, and perhaps in similar benthic mats in the lakes and streams of southern Victoria Land.

The lipid composition of natural populations of diatoms in the sea ice at McMurdo Sound was determined during the austral spring bloom of 1985, using and Iatroscan TLC–FID system. The major lipid classes in all samples were polar lipids (including phospholipid, glycolipid and chlorophyll) and triacylglycerol, with lesser proportions of free fatty acids. Total lipid increased through November and early December, reaching a maximum (3300 mg m−2 at Cape Armitage and 1800 mg m−2 at Erebus Ice Tongue) c. one week after the chlorophyll a maxima. This increase was largely attributable to a corresponding increase in triacylglycerol. At the lipid maxima, triacylglycerol/polar lipid ratios in the range 1.0 to 2.5 were observed. The dynamic variations in lipid class abundances indicate that profound changes in the physiology of sea-ice diatoms are occurring throughout the spring bloom. A range of sterols (C26–C30) were detected; 24-methylenecholesterol, brassicasterol and 24-ethylcholesterol were the major sterols at the Cape Armitage and Erebus sites. The similarity of the sterol profiles to those of Antarctic freshwater algal communities strongly indicates diatoms as a more probable source of C29 sterols in the freshwater lakes than cyanobacteria or other algal groups. The hydrocarbons isolated from sea-ice diatoms at all sites were dominated by two unsaturated components, n−C21:6 and a diunsaturated isoprenoid C25 alkene. Until this study, no biological source had been validated for the isoprenoid C25:2 diene, even though it has been detected in many estuarine and coastal sediments.

Zooplankton was sampled intensively with an RMT 1+8M system in the fjord of Cumberland East Bay, South Georgia during late winter 1983 and summer 1987. In summer, biomass was highest in the surface 20 m, reaching 142 g dw/1000 m3. Copepods dominated the zooplankton comprising 96–99% by numbers, of which 80–90% occurred in the top 100 m of the 265-m water column. The small clausocalanid Drepanopus forcipatus was particulary abundant. With increasing depth the proportion of non-copepod biomass, principally Mysidacea and Amphipoda increased significantly. Biomass throughout the water column in winter was generally 4–5 times lower than in summer although again copepods, and in particular D. forcipatus and members of the Metridinidae, still numerically dominated the plankton. Biomass levels were some 2–3 times greater than those found in Antarctic oceanic regions but were comparable with estimates from some boreal fjords. The mixture of neritic and oceanic species encountered, and the seasonal presence of some gelatinous zooplankton, particularly ctenophores, appears typical of the community structure of many fjord ecosystems.

The southernmost exposures of Mesozoic dolerites in Coats Land, the Omega dolerites, occur at Whichaway Nunataks. The dolerites are geochemically indistinguishable from the Theron Mountains' dolerites. In both regions high- and low-Ti compositions occur with trace element signatures more akin to island-arc magmas than within-plate tholeiites. From a preliminary Sr isotopic study the Omega dolerites can be classified as Ferrar type. The existence of Ferrar type material in these nunataks suggest that the boundary between the Ferrar and Weddell Sea sub-provinces occurs within the Theron Mountains.

A normal mode approach is used to model the behaviour of a linearly-damped, elastic, ice beam floating on a fluid foundation and subjected to a random distributed loading. As an example, two loading regimes are considered to act on the Erebus Glacier Tongue, McMurdo Sound: broad bandwidth (‘white noise’) loading, and an ocean wave-type pressure distribution beneath the tongue. For white noise input, the root mean square (rms) deflexion is found to good accuracy within the first few modes, but the rms bending moment increases with the number of modes included in the summation due to the unlimited frequency content of the forcing. Solutions for the rms deflexion and bending moments quickly converge to their mathematical limit after six modes when the forcing is due to ocean waves. A local maximum in rms bending moment near the end of the beam confirms that waves may be important as a mechanism for iceberg calving.

Recent geomorphological research in the ice-free areas of West Antarctica and the subantarctic islands has begun to provide an outline glacial chronology that helps our understanding of the late Quaternary history of ice sheets. However, there is a need for detailed studies of the glacial history of the Antarctic Peninsula area and its offshore islands before a general chronology can be fully reliable. In particular, evidence of Neoglacial glacial fluctuations in the area are imperfectly known in spite of work by Sugden & Clapperton (1977) on island groups in the Scotia Sea, Clapperton et al. (1978) on South Georgiaand Clapperton & Sugden (1982) on Alexander Island. The aim of this note is to present data relating to Holocene glacier fluctuations from the hitherto unstuded Brabant Island (64°15′S, 62°3′W).

The structural basement of Alexander Island consists of a wide belt of accretionary complex rocks, the LeMay Group (Bum 1984). This is overlain by ?Cretaceous-Tertiary calcalkalinevolcanic rocks (Bum 1981), and intruded by several slightly younger, but related, plutons (Care 1983). The Rouen Mountains batholith is a large group of these plutons which occurs in the northern part of the island.

Wind and temperature profiles in the lowest 2000 m of the atmosphere at Halley (75°35′S, 26°50′W) have been analysed. Surface winds blow most frequently from the sector 090° ± 45° but the 2000 m wind direction is much more evenly distributed and appears to be determined by synoptic-scale pressure gradients. A simple one-dimensional boundary layer model, which includes the effects of stably-stratified air overlying a sloping surface, is able to reproduce some of the features of the observed profiles.