At the ice edge krill undergoes diurnal migrations with the period of 12 hours and amplitude of about 6 meters. The mean depth of krill occurrence is 41 m, shallower then for open waters. In our opinion these migration parameters are characteristic of juvenile adolescent krill dominating at the ice edge.

The method of target strength measurement adopted for the krill's target strength determination is proposed. The relation between the length of krill's individual and its target strength, obtained at the laboratory conditions, is presented.

Studies on performance capacity and selectivity of trawls used for industrial fisheries of krill (Euphausia superba) were carried out on the research vessel r/v „Profesor Siedlecki". It has been ascertained that performance capacity of the proposed trawl is about 0.86 and that chiefly small, 22—26 mm-long, krill specimens are passing through the trawl segments made of 12 mm-meshed fabric. This has an essential effect on the age-size structure of caught specimes of krill. It has been stated that the insets of less than 10 mm-mesh fabric in the bags and less than 12 mm-mesh fabric in the bellies of the trawl are practically inexpedient.

An attempt at assessing the correlation between the content of fluoride in the Antarctic krill from various fishery and its.biological condition was carried out Fluoride was determined with the Dolan method, which was modified by the present authors. No statistically significant correlation was found between the degree of sexual maturity and fluoride content. There was no decisive statistical relation between the body weight and body length of individuals and the content of fluoride in the Antarctic krill.

Concentration of Zn, Cu, Cd, Pb and Co have been determined in Antarctic water (South Shetland Islands) and in krill exoskeletons with the help of atomic absorption spectrophotometry. Concentrations of these metals both in sea-water and in krill exoskeleton are in order Zn > Cu > Cd > Ni > Pb > Co. Comparing concentrations of these metals in sea-water to their concentrations in krill exoskeleton, the factors have been calculated giving a list of metals in the order of krill chitin ability, which is Ni > Cu > Zn > Cd > Pb > Co accumulation. The highest accumulation factors for Ni and Cu point out to the special role played by these metals in krill life.

The photo-oxidability of lipids taken from 32 samples of krill from different dates of catch has been examined for photooxidation. Relations were indicated between the rate of accumulation of peroxides in the process of lipids, exposure and content of lipids in krill, its iodine value and amount number of carotenoids.

A composition of lipids of some Antarctic Crustacea (Euphausia superba. E. triacantha. Thysanoessa macrura and Mysidacea gen. sp. indet.) caught in the Admiralty Bay (South Shetlands) was compared. Lipids of E. superba differed in low content of waxes that evidences for different management of lipids than in other examined Crustacea.

Using a thin layer chromatography the content and composition of krill lipids was examined in different sex and maturity stages. The content of lipids decreased in the following sequence: immature males — females with eggs — juvenile specimens — spent females — mature males. In females the differences concerned mainly phospholipids and waxes, in males — triacylglicerols; this fact proves the different utilisation of lipids for reproduction in both sexes.

On the basis of acoustically registered cross-sections of krill aggregations, regular, irregular and layer forms were distinguished. Regular forms are most frequently observed during spring and in the day time, while irregular forms are most frequent during summer and night hours. The density histograms made for two hour intervals clearly show the day-night difference, but the seasonal (spring, summer) difference is less pronounced. Mean density of swarm is lowest during the night and reaches a maximum in early morning hours. The mean volume backscattering strength values (Sv) for spring and summer are nearly identical. We suggest that regular forms correspond to foraging swarms and irregular forms to feeding swarms as described by Hamner (1984).

On the basis of measurements of the depth of occurrence of 11000 krill aggregations and the biological analyses of these animals and measurements of some environmental factors the diurnal vertical distribution of aggregations is presented against the background of various environmental conditions. Vertical distribution of aggregations is closely related to the feeding rhythm of krill. Active vertical migrations have been recorded at civil twilight. The increasing and decreasing rate of aggregations in those periods is described.

The presence of Euphausia superba, E. crystallorophias and Thysanoessa macrura was observed in Admiralty Bay (King George Island, South Shetland Islands) and the size of individuals of particular species are diverse and varying during the summer season. E. superba population is older and specimens larger than in analogous season in 1979. The maximum number of females with eggs was noted in the first half of January 1980, i.e. earlier than in 1979. In E, crystallorophias population the presence of females with eggs was observed in the second half of December 1979.

The highest infestation by phoronts (resting stages) of Apostoma ciliates forms 1, 2, is restricted to the 3-th and 4-th pairs of E. superba thoracic limbs. They occur mostly on meropodites of endopodite and plumose setae of exopodite. The trophonts (trophic stage) of those Apostoma are present in large numbers in krill's tissue. The life cycle of those histophagous Apostoma include also free-living stage - tomit. Swarm formed by krill seems to be a reason for the common and extensive infestation by protozoans.

This bibliography presents a list of 169 papers of Polish authors, treating on the Antarctic zooplankton. The majority of these papers (67%) concern Antarctic krill (Euphausia superba Dana), mainly its biology, ecology and physiology. Quite numerous papers by Polish authors concerning the biochemistry of krill as well as its fishing technique and food - processing are here omitted.

In the investigated area the overall abundance of krill was small and was increasing with the distance from ice. However, with the data available, it was not possible to decide whether this increase was related to the ice border or was a part of a larger scale phenomenon. The depth distributions as well as the mean values of krill depth were similar to those of open water both in this study and reported in literature.

Results from the hydro-acoustic studies aiming at evaluation of the Euphausia superba biomass in the Bransfield Strait in March 1981 are presented. These investigations, called conventionally Micro-FIBEX, were carried out on the r/v "Profesor Siedlecki" during 13-16 .March 1981, as continuation of the studies carried out in that region within the scheme of the FIBEX programme in the period of 5-12 March 1981. The abundance of the biomass was estimated at 258 thousand ton, which at the investigated area of about 1755 NM2 gives the mean value of biomass density 142 t/NM2 (41.4 g/m2).

The amount and composition of lipids m some Antarctic animals were studied. The material consisted of crustaceans (Euphausia superba, Paramoera sp., Orchomene sp.), tunicates (Salpa thompsoni) and vertebrates (Notothenia rossi marmorata and Hydrurga leptonyx). The author's data are discussed on the background of available literature information.

During SIBEX the acoustically evaluated amount of krill in the Bransfield Strait and Drake Passage was very low with the mean density 3.24 individuals/m2 and 4.29 individuals/m2 accordingly. Any substantial quantities of krill were found North-West from the Elephant Island and North from the King George Island, where the density of krill exceeded 1000 individuals/m2 (about 100 t/nM2]). The total biomass was estimated at 70590 ton in the Bransfield Strait and at 122470 ton in the Drake Passage, which was many times less than during FIBEX 81, especially in the Bransfield Strait.

In 25 krill samples (Euphausia superba) collected at the Scotia Sea and in the area of South Georgia, South Orkney and South Sandwich Islands, Antarctic Peninsula and the eastern part of the Bellingshausen Sea the concentrations of Cd, Pb. Zn, F, 90Sr, 137Cs, U and 239, 240 Pu has been determined. The corresponding average concentrations were found to be: Cd — 2.5, Pb — 3.4, Z n — 123.1 , F — 50 (ppm dry weight), 90Sr— 1.9, 137Cs — 4.7 (mBq x -1 dry weight), U — 11.1 (ppb dry weight) and 239, 240Pu - 0.08 (mBq x g-1 dry weight).

Recording of krill swarms and the observations of the state of the sea and the force of wind were conducted on the M/T "Gemini" from 6 to 26 February, 1978, eastwards of the South Orkneys Archipelago. It has been found that a heavy sea and strong winds disperse krill swarms. At night krill swarms occur much more frequently than during the day.

Observations on abundance and distribution of juvenile fish within the krill concentrations were made during February—March 1981. Juvenile and scarce postlarval stages belonging to 23 species of the suborder Notothenioidei were recorded in the investigated area. Chionodraco rastrospinosus and Chaenodraco wilsoni were the most frequent and numerous species. Juvenile fish, as well as extensive concentrations of krill, were recorded mainly in the southern part of the Bransfield Strait and in the shelf waters westwards of the Palmer Archipelago. The juveniles were however absent in the open waters of the Drake Passage.

Studies were carried out in the region of southern. Drake Passage and Bransfield Strait in February and March 1981. The relation occurring between the alimentary tract filling (ATF) and the quantity of chlorophyll α integrated within the range of 0-150 m water-layer may be described by Ivlev's equation expressing the amount of the food ration in relation to food concentration. The ATF value increases in large individuals and is proportional to their body weight. The daily rythm of krill feeding, expressed by ATF, depends on the quantities of food in the environment.

Stocks of krill in the southern part of the Drake Passage and in the Bransfield Strait were estimated by the hydroacoustic method, during the BIOMASS-FIBEX expedition (Febr.-March 1981). Krill stocks in the Drake Passage and Bransfield Strait were assessed at about 1.2 and 2.3 mln tons, respectively. A map of krill distribution in these regions was prepared. The main krill biomass (66%) was found to occur within the Bransfield Strait which accounts for only 13.7% of the total area under survey.

The compilation of experimental data on krill target strength is performed and results compared with the theory. A modification of the Johnson's theory is proposed to fit experiment.

The length of crystalline cones (cc) is proportional to krill body length and this proportion can be described by the equation L cc = L krill x 1.679 + 52.032 ( cc — μm; L krill - mm). By measuring cc one can determine the size of krill with the precision of 2—3 mm. The structure of crystalline cones is not crystal, and the elemental composition includes much of S and Ca. Crystalline cones are often found in the stomach and feces of animals feeding on krill.