Maximum values of the settling volume and dry weight of suspended particulate matter, were found in the open waters of the southern Drake Passage (between 60°8' S and 62° 11' S), and west of the Anvers Island. Minimum respective values were observed in the Bransfield Strait. The distribution of phytoplankton cell numbers and of algal biomass expressed as total cell volumes closely followed the distribution of particulate matter. Diatoms were the major algae of the plankton. Several species of the genera Chaetoceros, Nitzschia and Corethron were dominant and characteristic of the phytoplankton assemblages in different parts of the study area.

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.

Zooplankton samples taken in February and March 1981 in the southern Drake Passage and the Bransfield Strait revealed distinct differences between animal communities inhabiting water masses of different origin and of different physico-chemical properties. The West Wind Drift waters of the Drake Passage were rich in zooplankton; they were characterized by a high abundance of Radiolaria and young Limacina sp., the constant occurrence of Rhincalanus gigas, a significant share of Clausocalanus sp. and Calanoides acutus. On the other hand the above mentioned forms were nearly absent or scarce in the much poorer waters adjacent to South Shetland Islands and especially waters of the Bransfield Strait where such copepods like Metridia gerlachei and Oncaea curvata dominated or at least played a significant role being rare and scarce or absent in the Drake Passage. This picture was especially clear in the upper 100 m water layer, whereas in the deeper layer (300-100 m) these quantitative and qualitative differences were less obvious.

In the region under investigations 30 species of seabirds were observed. In the southern part of Drake Passage Daption capense. and Oceanites oceanicus predominated quantitatively, Macronectes giganteus, M. halli and Pachyptila spp. were subdominant. The vessel was often accompanied by Diomedea exulans. In the Bransfield Strait Fulmarus glacialoides, D. capense and O. oceanicus were predominant. M. giganteus was subdominant. The estimated value of the biomass of seabirds was the highest in the region to the west of Elephant Island, slightly lower in the region of Anvers Island, Smith Island and Livingston Island, and the lowest in the south-eastern part of Bransfield Strait and the middle part of the investigated region of Drake Passage.

In the investigated area, mass occurence of krill was observed in the vicinity of islands and the Antarctic Peninsula, in the waters above the shelf and shelfs slope. Small quantities of krill were found in the open oceanic waters. Immature individuals dominated close to the Antarctic Peninsula. Large, sexually mature kril dominated farther from the continent. Gravid females contributed little to the total populations. Krill of the largest size occured near the Palmer's Archipelago, and of the smallest size at the Antarctic Peninsula and the Elephant Island. It is likely that krill observed west and north of the Palmer Archipelago had been brought by currents from the Bellingshausen Sea. Krill in the Bransfield Strait originated probably from the mixing of populations carried by currents from the Weddell Sea and the Bellingshausen Sea.

Following compounds were determined in samples from Bransfield Strait and southern part of Drake Passage (area "A"): dissolved free- and combined amino acids, dissolved mono- and polisaccharides and urea. Concentration of urea in most samples ranges from traces to 1.5 μgat Nurea-1 and total urea content in water column from 10 to 150 m lies between 19.23 and 197.4 mgat Nurea . Dissolved free amino acids concentration ranges from 0 to 0.60μg x 1-1 and total free amino acid content are found to be between 20 and 60 mmol. Concentrations of combined amino acids lay below 7 μmol x 1-11 and integrated value for combined amino acids fluctuates between traces and 450 mmol. Monosaccharides concentrations in most samples do not exceed 2.5 μmol x l-1 and their content in water column lies below 180 mmol. Polysaccharides content in water column ranges from 1.8 to 3.94 mol and concentrations vary between 8 and 32 //mol-1 1. Evident differences in the content of dissolved organic compounds between Bransfield Strait and southern part of Drake Passage were found.