Polish Polar Research

Phytoplankton samples were collected at 74 stations in the European Arctic seas, 28 species of the armoured din oft age Hates being found. Thirteen dinoflagellates are illustrated by original drawings. The data on synonyms, size or size variation, localities and environmental factors (temperature and salinity) at the surface are given.

Chlorophyll α, phytoplankton, suspensions and zooplankton beneath the fast ice have been studied in Spitsbergen fjords (Hornsund, Bellsund, Sassenfjord, Gronfjord and Kongsfjord) in 1982, 1984/85,1987 and 1988. Observations on ice associated Polar cod and wildlife have been collected simultaneously. There were no typical sympagic communities observed at the West Spitsbergen fast ice. Exception was spring 1982 and 1988 when drifting ice from Barents Sea contributed to the fjords fauna. Fast ice on the investigated fjords was poor in adjacent zooplankton (biomass below 0.06 g/m3). Ice phytoplankton reflects the autumn situation and no specific communities of algae have been found. Chlorophyll α amount and organic sedimentation from ice and from the adjacent water were very similar (0.4 to 1.7 mg/m3 chlorophyll and 8 to 10 g d.w./m2/day sedimenling matter). The diet of Polar cod reflected the food items occurrence, Calanus has been the most common food. N o specific concentration of seabirds have been observed at fjords ice.

Physical and chemical properties (granulometric composition, pH, carbonates, organic carbon, nitrogen etc.) as well as bioenergetic activity of Spitsbergen tundra soils were studied at three chosen stations situated near Polish polar station "Hornsund". It was found that biological activity of Arctic tundra soils depended mainly on its physical properties, whereas the chemical composition of organic matter did not effect directly the bioenergetics of these soils. This bioenergetic activity depends mainly on the richness of micro- and mesofauna communities inhabiting the soil.

The paper deals with the structural variability and generative reproduction of Saxifraga oppositifolia populations in eight localities situated in Western Spitsbergen. The localities differed in terms of humidity, soil fertility, microclimate and frequency of disturbances. The population structure, the growth and development rate of individuals in the sea terrace and at the peat-bog prove that a dense plant cover influences positively the development of S. oppositifolia. The size of individuals, their biomass and population density is limited in most of the studied localities. Solifluction is the factor influencing the development of a population to the greatest extent. Of all the researched populations the weakest development was observed in the active structural grounds. Yearly changes in the structure of the populations as well as the yearly growth of the species studied are limited. The longevity, the development rate and size of the seedling recruitment are subject to modifications caused by the solifluction.

Net phytoplankton cell numbers in 50 m water column of Admiralty Bay ranged between 0.2 x 10 5 x m-2 on 24 August 1990 and 2.3 x 10 7 x m-2 on 15 November 1990. Cluster analysis has confirmed the presence of two groups of samples: spring and summer ones (October to April), rich in cells and in species, and, on the other hand, winter samples (June to August) impoverished in algae. Spring and summer fluctuations of diatoms were mainly due to Corethron criophilum, Rhizosolenia alata and its varieties, R. hebetata f. semispina, Thalassiosira spp., Chaetoceros spp., and Nitzschia spp. (Fragilariopsis and Pseudonitzschia groups). The abundance and succession of species in Admiralty Bay reflect seasonal differences in diatom growth; they also reflect mixed populations of the Weddell and Bellingshausen seas entering Admiralty Bay via Bransfield Strait. Striking poverty of algae in some summer samples can most likely be attributed to zooplankton grazing.

In the material collected in 26 stations along the course of three creeks in the vicinity of Polish Antarctic Station 183 taxa of algae have been identified: 25 of Cyanophyta, 123 of Bacillariophyceae, 2 of Xanthophyceae, 2 of Chrysophyceae and 31 of Chlorophyta. The highest species diversity was found in the algal community in Creek II (132 taxa), the second place was occupied by the "Petrified Forest Creek" (97 taxa), and the least diversified algal community was that from the "Ornithologists' Creek" (73 taxa).

Results of Polish biological investigations and surveys on the state of mackerel icefish (Champsocephalus gunnari Lonnberg, 1905) stock served to undertake an attempt at an independent estimation of some of its biological parameters as well as at the assessment of its biomass and fishing mortality during 1975/76—1991/92 fishing seasons with virtual population analysis (VPA) method (using MAFFVPA programme). Laurec-Shepherd and hybrid methods were applied for the VPA tuning. Von Bertalanffy equation parameters were estimated and compared with those published earlier. F0l and F max values were assessed

using Beverton and Holt model and Thompson and Bell method. Based on data from available literature the coefficient of natural mortality (M) was assumed to be 0.5. VPA results indicate that the total stock biomass (TSB) during the last 1991/92 season amounted to 34,818 tonnes and was approximately 10 times lower than in 1975/76 season. Spawning stock biomass (SSB) declined to a minimum of 7,396 tonnes in 1989/90 season. The assessment results point out to the recruitment as a major factor contributing to the stock fluctuations.

Flying bird counts were carried out at Esperanza Bay (62°24'S, 56°59'W), Antarctic Peninsula, between November 1989 and February 1990. Six breeding species (Oceanites oceanicus, Chionis alba, Catharacta lonnbergi, Catharacta maccormicki, Larus dominicanus and Sterna vittata) and six visitor species (Macronectes giganteus, Fulmarus glacialoides, Daption capense, Pagodroma nivea, Fregetta tropica and Phalacrocorax atriceps) were recorded. Kelp gull and Antarctic tern populations have decreased in relation to the data by previous authors, perhaps as a result of the increased activity at Esperanza Station. Cygnus melanocoryphus was recorded for the first time at Esperanza Bay.

Pinnipeds were monitored in Admiralty Bay between 1988 and 1992. No particular trends during this period were found, but seasonal changes in each are distinct. It is suggested that the phenology of pinnipeds and that of penguins ensures low competition for food between these groups.