The Bulletin of the Polish Academy of Sciences: Technical Sciences (Bull.Pol. Ac.: Tech.) is published bimonthly by the Division IV Engineering Sciences of the Polish Academy of Sciences, since the beginning of the existence of the PAS in 1952. The journal is peer‐reviewed and is published both in printed and electronic form. It is established for the publication of original high quality papers from multidisciplinary Engineering sciences with the following topics preferred: Artificial and Computational Intelligence, Biomedical Engineering and Biotechnology, Civil Engineering, Control, Informatics and Robotics, Electronics, Telecommunication and Optoelectronics, Mechanical and Aeronautical Engineering, Thermodynamics, Material Science and Nanotechnology, Power Systems and Power Electronics.

Journal Metrics: JCR Impact Factor 2018: 1.361, 5 Year Impact Factor: 1.323, SCImago Journal Rank (SJR) 2017: 0.319, Source Normalized Impact per Paper (SNIP) 2017: 1.005, CiteScore 2017: 1.27, The Polish Ministry of Science and Higher Education 2017: 25 points.

Abbreviations/Acronym: Journal citation: Bull. Pol. Ac.: Tech., ISO: Bull. Pol. Acad. Sci.-Tech. Sci., JCR Abbrev: B POL ACAD SCI-TECH Acronym in the Editorial System: BPASTS.

We talk to Dr. Katarzyna Błachowiak-Samołyk, professor at the Department of Marine Ecology at the PAS Institute of Oceanology in Sopot, about the impact of human activity on life in the oceans.

High−frequency acoustic measurements supplemented by a modern optical method, Laser Optical Plankton Counter (LOPC), allowed us to perform a comparative analysis through the application of a mathematical model. We have studied the correspondence between measured and modelled echoes from zooplankton aggregations consisted mainly of two Calanus species. Data were collected from the upper 50 m water layer within the hydrographical frontal zone on the West Spitsbergen Shelf. The application of a “high− −pass” model of sound scattering by fluid−like particles to the distribution of zooplankton sizes measured by LOPC resulted mostly in very good agreement between the measured (420 kHz BioSonics) and modelled values, except for cases with very low zooplankton abundance or with occurrence of stronger scatterers ( e.g. macrozooplankton, fish). An acoustic model validated for the elastic parameters of zooplankton confirmed that particles smaller than 1 mm in diameter, although highly abundant, did not contribute significantly to the sound scattering process at a frequency of 420 kHz. The implementation of diverse complementary methods has great potential to obtain high spatial and temporal resolution in zooplankton distribution studies; however, their compatibility has to be tested first.

Four Ostracoda species belonging to one family, Halocyprididae, were found in plankton material collected from the Scotia Sea and off the King George Island (the Antarctic) during the austral summer 1988/1989. Alacia belgicae, A. hettacra and Metaconchoecia isocheira were dominant making up to nearly 99% of all Ostracoda. The horizontal distribution was modified by variability of hydrological conditions. The higher concentrations of chlorophyll a and phytoplankton, which were found in the mid- and eastern parts of the Scotia Sea, coincided with the highest densities of Ostracoda. The influence of ice pack presence in the Scotia Sea upon the higher abundance of Ostracoda in the period investigated in comparison with the earlier studies was distinctive. A vertical distribution analysis confirmed that the three above-mentioned endemic species were most abundant in the mesopelagial. The population structures of A. belgicae, A. hettacra, and M. isocheira were analysed. The presence of the youngest stage of A. belgicae in the Scotia Sea confirmed the beginning of reproduction of this species at that time. The vertical distribution patterns of A. hettacra and M. isocheira populations were similar, although their age structures in comparison with A. belgicae differ significantly. This was consistent with their higher “mean population stage” values.

The material discussed in this paper was collected in the Drake Passage and Bransfield Strait (Antarctica) within the framework of the BIOMASS-SIBEX programme. Samples were collected by hauling Nansen nets verticaly through the 100 — 0, 300—100 and 500 — 300 m layers in December 1983 and January 1984. Of the six species recorded — Metaconchoecia isocheira, Alacia hettacra, Alacia belgicae, Metaconchoecia skogsbergi, Boroecia antipoda and Discoconchoecia off. elegans — the first three, endemic to Antarctic waters — were predominant (92.9%). Ostracoda were found most abundantly in the eastern part of the study area — between Elephant Island and South Orkney Islands, and in the south-western part of Bransfield Strait. Their vertical distribution depended on the hydrological conditions. Ostracoda were most numerous in the 500—300 m and 300 — 100 m layers; very few were recorded in the 100—0 m surface layer.

Material for this paper was collected during the BIOMASS-SIBEX research programme, and consisted of 97 samples taken at 47 stations in Drake Passage and Bransfield Strait (Antarctica). The samples were taken by hauling Nansen nets vertically through the 0-100, 100 - 300 and 300 - 500 m layers at the end of December 1983 and the beginning of January 1984. Four Chaetognatha species were recorded in the study region: Eukrohnia hamata, Sagitta gazellae, Sagitta mari and Sagitta planctonis. The population structures of the dominant species E. hamata and also S. gazellae were analyzed in the context of the region's hydrology. Certain regularities are apparent in the distribution of the developmental stages of E. hamata in water column. Mature specimens of this species inhabit deeper waters than juveniles. The highest proportions of juveniles in the entire population of E. hamata were recorded in slightly warmer waters.

The distribution of planktonic Ostracoda (Halocyprididae) was studied based on vertically-stratified zooplankton samples collected by hauling 200 p.m - mesh net by day and by night during two austral seasons: summer 1985/1986 and winter 1989, from the 1200 m deep Croker Passage off the Antarctic Peninsula. Seven species of Ostracoda were recorded: Alacia belgicae, Alacia hettacra, Melaconchoecia isocheira, Metaconchoecia skogsbergi, Boroecia antipoda, Disconchoecia aff. elegans and Proceroecia brachyaskos. The first three species, endemic to Antarctic waters, were predominant (about 90%). Generally Ostracoda were most numerous in 600-200 m layer in summer and in 1000-400 m layer in winter. In the investigated area there was a clear contrast between the abundance of Ostracoda during austral summer and scarcity during austral winter.

During a midwinter cruise north of 80oN to Rijpfjorden, Svalbard, the composition and vertical distribution of the zooplankton community were studied using two different samplers 1) a vertically hauled multiple plankton sampler (MPS; mouth area 0.25 m2, mesh size 200 μm) and 2) a horizontally towed Methot Isaacs Kidd trawl (MIK; mouth area 3.14 m2, mesh size 1500 μm). Our results revealed substantially higher species diversity (49 taxa) than if a single sampler (MPS: 38 taxa, MIK: 28) had been used. The youngest stage present (CIII) of Calanus spp. (including C. finmarchicus and C. glacialis) was sampled exclusively by the MPS, and the frequency of CIV copepodites in MPS was double that than in MIK samples. In contrast, catches of the CV-CVI copepodites of Calanus spp. were substantially higher in the MIK samples (3-fold and 5-fold higher for adult males and females, respectively). The MIK sampling clearly showed that the highest abundances of all three Thysanoessa spp. were in the upper layers, although there was a tendency for the larger-sized euphausiids to occur deeper. Consistent patterns for the vertical distributions of the large zooplankters (e.g. ctenophores, euphausiids) collected by the MPS and MIK samplers provided more complete data on their abundances and sizes than obtained by the single net. Possible mechanisms contributing to the observed patterns of distribution, e.g. high abundances of both Calanus spp. and their predators (ctenophores and chaetognaths) in the upper water layers during midwinter are discussed.

Sixty seven zooplankton taxa were recorded in a total of 5 WP-2 net vertical hauls carried out in a year round cycle in Admiralty Bay. Copepoda were the most common and abundant group and Oithona similis was the dominant species throughout the area. Polychaeta, Ostracoda and Chaetognatha were also rather common and abundant. Euphausiacea, Amphi-poda and Salpae occured mainly in the central part and the outlet area of the bay. No differences in zooplankton assemblages diversity in the four investigated areas of Admiralty Bay were en­countered. However, distinct differences in species richness between the zooplankton of Ezcurra Inlet and the main basin of the bay were observed. The composition of zooplankton was rather stable throughout the year, but seasonal occurrences of larvae of Polychaeta, Crustacea, Echino-dermata and Ascidiacea were noted. A Ust of the 174 zooplankton taxa ever found in Admiralty Bay is presented by combining the present results with the existing scientific data.

The food and foraging strategy of fifteen species of seabirds and sea mammals from two high Arctic fjords were analysed. One of the fjords, Kongsfjord, is strongly influenced by warm waters from the Atlantic , while Hornsund is of a more Arctic character. Prey species in the Atlantic waters were more diverse (82 species and 16 functional groups) compared to those of Arctic waters (67 prey species and 14 functional groups). The consumption of top predators from Hornsund in the peak season of July was estimated at 2.86*106 MJ, while that in Kongsfjord was 1.35*106 MJ. For the analysed function of the ecosystem (the transfer of energy to the top trophic levels) the specific character of prey species is of key importance and not the diversity, abundance or biomass per se. Lower species diversity and biomass in Arctic waters is compensated for by the occurrence of larger individuals of these species, which permits top predators to prey directly on lower trophic levels.