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doi: 10.1111/j.1095-8312.1980.tb00093.xpmid: N/A
A tradition of biological research in the Antarctic was established by Cook 200 years ago. This tradition has been built on by other British expeditions, notably the ‘Discovery’ Investigations. The British Antarctic Survey, which arose from Operation Tabarin and the Falkland Islands Dependencies Survey, now carries out a programme of coordinated and continuous biological research. The Atlantic sector of the Antarctic, in which the Survey operates, is of key importance biologically. The Antarctic provides a striking biological contrast between a species‐poor and very barren terrestrial ecosystem and the species‐rich and productive ocean which surrounds it. Severe climatic conditions and great isolation (a contrast to the Arctic) characterize the Antarctic environment. Work at the Survey's biological research stations is designed to study the distribution and interactions of organisms and communities, how they have adapted to Antarctic conditions, and which by their abundance may be deemed successful. Research is done into terrestrial, fresh‐water and marine systems. Additionally, there is a major research programme into the biologv, environment and principal predators of krill, Euphausia superba. The Antarctic is a laboratory where opportunities exist for natural experiments to test theories and elucidate basic biological problems.
doi: 10.1111/j.1095-8312.1980.tb00094.xpmid: N/A
The Signy Island terrestrial reference sites epitomize unpolluted maritime Antarctic tundra. The extreme transition from the harsh Antarctic winter to the milder summer facilitates studies of the effects of freeze‐thaw cycles on microbial activity in moss peat. Seasonal monitoring of peat oxygen uptake showed a transient spring peak at c. 0oC, attributed to microbial utilization of dissolved organic carbon (DOC). After a more gradual temperature‐linked summer increase, autumnal freeze‐thaw cycles stimulated a final pre‐winter peak. The transient climaxes were associated with blooms of saccharolytic yeasts and microfungi. The bacterial population stabilized after a spring increase but then diversified as DOC became rate‐limiting. Effects of pre‐monitored spring freeze‐thaw cycles on late‐winter peat cores were simulated in a Gilson respirometer. In vitro perturbations demonstrated the regulatory effects of DOC availability, water content and temperature on peat respiration and microflora! composition. Comparative respirometry and loss in tensile strength of interred cotton strips showed a difference in decomposer activity beneath a relatively dry Polytrichum‐Chorisodontium turf and a wet Cattiergon‐Cephalozielta carpet. This was associated with water content and anaerobiosis. Cellulolysis accelerated during the growing season and increased with depth, despite anaerobic conditions. Estimates of annual bryophyte decomposition are presented for use in an Antarctic ecosystem model.
doi: 10.1111/j.1095-8312.1980.tb00095.xpmid: N/A
Three components of the survival strategy of a terrestrial Antarctic mite, Alaskozetes antarcticus (Acari: Cryptostigmata) are considered: overwintering survival, energetics and life history. Supercooling is an important feature of its cold tolerance, whilst elevation of standard metabolism allows activity at low temperatures, both of which contribute tcTa long development and maximum survival of individuals in the population. These are facets of the overall survival strategy evolved by such a species in response to the Antarctic terrestrial environment, but which may be widespread in polar invertebrates.
doi: 10.1111/j.1095-8312.1980.tb00096.xpmid: N/A
Oxygen uptake by the peat of two Antarctic bryophyte communities (a moss turf and a moss carpet) is converted to organic matter loss and used to derive the rate of decomposition. The decay rates obtained in this way are evaluated in two mathematical models which simulate the accumulation of dead organic matter (DOM) in the communities from the litter production and decomposition rate. Litter production, the extent of DOM accumulations at present on the sites and mean decomposition rates (i.e. fraction of standing crop lost per year) were 409 g m‐2 year‐1, 33.5 kg m‐2 and 0.017 g g‐1 year‐1 in the moss turf and 392 g m‐2 year‐1, 29.6 kg m‐2 and 0.010 g g‐1 year‐1 in the moss carpet respectively (all weights expressed as dry weight). Aerobic decomposition rate declined with depth in both communities. From the model's predictions it is suggested that the observed decay rate was too high in the moss turf and too low in the carpet. Possible reasons for this are discussed and suggestions made for future work.
doi: 10.1111/j.1095-8312.1980.tb00097.xpmid: N/A
Antarctic lakes present a wide variety of physical, chemical and biological conditions, and are not always the simplified systems imagined by earlier workers. The volume of data on lakes of various ages now allows informed speculation on the evolution of the Antarctic lake ecosystem.
doi: 10.1111/j.1095-8312.1980.tb00098.xpmid: N/A
The majority of Antarctic benthic invertebrates so far studied do not produce pelagic larvae, but develop non‐pelagically by means of egg capsules, brooding or viviparity. The predominance of protected development in the Antarctic benthos is primarily due to the short period of summer phytoplankton abundance and the low sea temperature. Such conditions make it difficult for a larva to complete pelagic development before food becomes scarce in the surface waters. Prosobranch gastropods illustrate some important aspects of Antarctic benthic invertebrate reproduction. Species which develop non‐pelagically have an aseasonal or prolonged spawning period. They produce a small number of large yolky eggs which remain in the benthos and develop slowly, giving rise to large, fully competent juveniles. Conversely, one species with free development has a short, synchronous spawning period during early summer, producing larvae which can benefit from the phytoplankton bloom. Protected development by means of brooding will limit dispersion, but transport on floating algae and by anchor ice may partially compensate for this in the Antarctic.
doi: 10.1111/j.1095-8312.1980.tb00099.xpmid: N/A
The concept of ‘metabolic cold adaptation’, namely that polar marine ectotherms are adapted in having an elevated basal metabolic rate, has been examined in the light of recent biochemical, physiological and ecological data for Antarctic marine organisms. It is now clear that marine invertebrates from Antarctic waters are characterized by slow growth rates, low basal metabolism and reduced annual reproductive effort, and there is thus no clear evidence of the traditional view of an elevated metabolic rate. By analogy with fish, protein synthesis rates are probably also low. This suggests that the major feature of cold adaptation is a reduction in the individual total annual energy intake in comparison with ecologically similar organisms from warm water. This allows a high standing crop of suspension feeders to develop, and low temperature is thus a significant factor in the successful widespread adoption of typical K‐strategies in Antarctic marine invertebrates.
doi: 10.1111/j.1095-8312.1980.tb00100.xpmid: N/A
Information on small scale distributions of three species of Antarctic zooplankton is reviewed. Aggregations of the euphausiid Euphausia superba, the tunicate Salpa thompsoni, and the amphipod Parathemisto gaudichaudii are compared, and the manner in which such aggregations mav arise is discussed. A possible relationship between swarming and feeding activity in E. superba is suggested in which krill are thought to be dispersed whilst feeding but that on repletion they swarm. It is thought that this may account for this species' irregular spatial distribution as recorded bv previous expeditions. A further consequence of this theory is that during the Winter swarming will be minimal.
doi: 10.1111/j.1095-8312.1980.tb00101.xpmid: N/A
At the sub‐Antarctic island of South Georgia 25 of the 29 breeding species are seabirds. Fifteen of these have recently been studied in some detail. By examining the timing of their breeding seasons and their diet and feeding ecology (especially feeding techniques and potential foraging ranges), the nature of their ecological isolating mechanisms, and in particular the way in which they partition the resources of the marine environment, are reviewed. Although breeding season adaptations occur (winter breeding in Wandering Albatross and King Penguin; out of phase breeding in two species‐pairs of small petrels) these are less important than dillerences in food and feeding ecology. There is a fundamental distinction between the niche of pursuit‐diving species (mainly penguins) and the remainder which are basically surface‐feeders. The two abundant krill‐eating penguins show clear differences in feeding zones. Three albatrosses and a petrel feed mainly on squid and there are differences in both the species and size of the prey of each. The remaining seabirds chiefly take krill (although the giant petrels are extensive scavengers and some smaller petrels specialize on copepods) and utilize different feeding methods and areas to do so. Various adaptations related to inshore and offshore feeding zones are discussed. Although most species possess a combination of ecological isolating mechanisms additional evidence for the particular importance of dietary differences is presented.
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