Polish Polar Research

Multidisciplinary research was carried on in 1978/79 in the region of Admiralty Bay and Arctowski Station. This area is representative of the near-shore Antarctic ecosystem. It is characterized by a number of local traits such as climate, ice conditions, hydrology, hydrochemistry and hydrodynamics. Estimates were made of primary production and abundance of zooplankton in Admiralty Bay and of the biomass and quantity of food taken by avi-fauna and pinnipeds. Main routes and directions of transport of mineral and organic matter are shown; some of them have been estimated quantitatively. A continuous inflow of organic matter from Bransfield Strait is necessary for the summer functionning of Admiralty Bay.

Admiralty Bay, which is the largest embayment on King George Island (South Shetland Islands, West Antarctica) has been geologically mapped by the present author between 1977 and 1979. The following rock-complexes have been distinguished: 1) evoic stratiform complex of andesitic and rhyolitic lavas and sediments (Martel Inlet Group and Cardozo Cove Group: probably Upper Jurassic); 2) Andean intrusions represented by gabbroic and dioritic dykes with associated pyrite-mineralization (Wegger Peak Group: approximately Cretaceous-Tertiery boundary); 3) Tertiary stratiform complex of basaltic and andesitic lavas and interstratified sediments, altogether more than 2700 m thick (King Island Supergroup: probably Eocene — Middle Miocene); 4) late Tertiary intrusive complex of basaltic and andesitic dykes and plugs (Admiralty Bay Group: probably boundary of Miocene and Pliocene); 5) late Tertiary effusives: olivine basalts, andesites etc., and sediments, about 600 m thick (Kraków Icefield Supergroup: Pliocene and ?earfy Pleistocene), with well preserved traces of two subsequent glaciations; 6) Quaternary intrusions (Cape Syrezol Group), Pleistocene) and effusives (Penguin Island Group: Holocene), mainly olivine basalts, related to opening of the Bransfield rift. An outline of structural history of King George Island is also presented.

The main current system occurring at Admiralty Bay is a two-phase flow system typical for fiords. Tidal waters are a decisive factor in determining the movements of water, whereas surface circulation is determined by winds, when the wind speed is higher than 4 m/s. The maximum values and directions of the surface drift current depend exclusively upon the actually prevailing wind field. The current speeds may reach the order of magnitude up to 100 cm/s. This flow lies above the two-phase system of currents generated by tides. The value of the currents produced by tides may reach up to ~50 cm/s. The direction of the current flow is not always in line with the corresponding of the tide. This is due probably to the irregularity and asymmetry of the tide and great inertis of the water masses.

Studies were carried out from December 1978 till February 1979. Quantities of suspended matter in the waters of Admiralty Bay ranged from 2.8 to 182.6 mg/1. The maximum quantities of suspended matter were recorded in the inshore zone, in particular at the mouths of the streams running off from the pielting glaciers. In the open regions of Admiralty Bay the average quantities of suspended matter were: 12.4 mg/1 in the upper water-layers, from 14.9 to 16.7 at the depth of 10-50 m and less than 10 mg/1 in deeper water-layers. The quantity of suspended matter drifting from the land into Admiralty Bay during austrial summer was estimated as averaging about 2000 tons per day.

Results from measurements and basic observations of meteorological elements carried out in 1978, at Arctowski Station situated on King George Island (South Shetland Islands) are presented.

The new species of antarctic skates was described from waters near Elephant Island, as a Raja rakusai sp. n.

During austral summer of 1979 in the area of Elephant Island ten species of fish representatives of five families, were identified.

Blood of 71 specimens of Notothenia rossii marmorata and 61 specimens of Notothenia neglecta from the region of Admiralty Bay (King George Island) was examined. The number of erythrocytes and hemoglobin content were higher in the blood of N. neglecta. The number of erythrocytes and hemoglobin content were similar in males and females of both species. Considerable differences were noted between individual specimens.

Observations were carried out in Penguin Island on 27 January 1979. The results of the birds census were as follows: Pygoscelis adeliae— 1710 pairs, P. antarclica— 7058 pairs, Macronecles giganteus—512 pairs, Oceanites oceanicus — 47 pairs, Chionis alba — 5, Stercorarius skua lonnbergi — 6 pairs, Larus dominicanus — 63 pairs, Sterna vittata—18. Other species showed different requirements as regards breeding grounds. Simultaneously the following Pinnipedia were observed on Penguin Island: Mirounga leonina — 202 specimens, Arctocephalus gazella — 48 adult and 6 young individuals, Leptonychotes weddelli — 2, Lobodon carcinophagus — 1.

Throughout 1978 regular counts of pinniped mammals were conducted along as 12-kilometre-long stretch of the Admiralty Bay coasts. The occurrence of all the six species of antarctic seals was noted, among them the most numerous were Mirounga leonina, Arctocephalus tropicalis and Lobodon carcinophagus. The number of these animals varied within a year-cycle. M. leonina and Leptonychotes weddelli breed at Admiralty Bay.