Ninety eight polychaete species were found in the shallow sublittoral of Admiralty Bay. The most abundant were Leitoscoloplos kerguelensis, Tauberia gracilis, Ophelina syringopyge, Rhodine intermedia, Tharyx cincinnatus, Aricidea (Acesta) strelzovi, Apistobranchus sp., Cirrophorus brevicirratus and Microspio moorei. Mean abundance of polychaetes was estimated at 120 ind./ 0.1m2. As a result of cluster analysis several polychaete assemblages were distinguished. The highly specific assemblage with two characteristic species, Scoloplos marginatus and Travisia kerguelensis, from shallow areas with sandy bottom situated far from glaciers; a distincly specific assemblage with Apistobranchus sp. from poorly sorted sediments in the bottom areas situated on the slopes at the base of steep rubble shores; the richest and most diverse, highly specific polychaete assemblage from the central basin of the bay with Tauberia gracilis as the most characteristic species, as well as two assemblages from the bottom areas neighbouring glaciers and influenced by the intensive enrichment of very small grain-sized sediments with Ophelina cylindricaudata and Tharyx cincinnatus. Clear assemblages’ arrangement was observed along the gradient: sand, silty sand, silt towards clay silt. Other important factors, supporting the proposed classification of assemblages and their character, include the sorting coefficient of the sediment (So) as well as the slope of the bottom. The between-habitat diversity of polychaete fauna is strongly connected with the phenomena occurring in the neighbouring terrestrial coastal areas.

The checklist of Admiralty Bay polychaetes elaborated on the basis of historical and current data includes 120 benthic and 5 pelagic species. Admiralty Bay is the most intensively sampled area in the Antarctic, taking into account polychaete fauna, and the checklist of Polychaeta may be therefore considered as a rather comprehensive one. In the sublittoral soft bottom three dominant species: Leitoscoloplos kerguelensis, Tauberia gracilis and Ophelina syringopyge constitute almost 50% of all collected polychaetes (20%, 16% and 13% respectively). Rhodine intermedia, Tharyx cincinnatus, Aricidea (Acesta) strelzovi, Apistobranchus sp., Cirrophorus brevicirratus, Microspio moorei, Maldane sarsi antarctica, Aglaophamus ornatus and Asychis amphiglypta make up a group of species of considerable abundance (a further 30% of author's collection). The average abundance of polychaetes of the sublittoral soft bottom was estimated at 120 individuals per 0.1 m2, with the observed maximum 390 individuals per 0.1 m2.

The distribution of pelagic Polychaeta in the Scotia Front region is presented. 6 polychaete taxa were recorded in the material with the most abundant Pelagobia longicirrata which constituted 86% of all collected specimens. The mixing of water masses in the frontal zone influence the quantitative distribution of polychaetes in the water column.

Lacydonia (Polychaeta: Phyllodocida) is a poorly known genus containing 16 species that are sporadically collected in low densities all over the world oceans. During three cruises (in June 2014 in Ullsfjorden, northern Norway, in January 2015 in Kongsfjorden, and in June 2012 in Smeerenburg, Svalbard) nine specimens of Lacydonia eliasoni were found on sandy and muddy sediments at depths from 180 to 350 m. All specimens were incomplete and consisted of 10 to 29 chaetigers. This study presents the first record of the Lacydonia genus in the waters of Svalbard as well as the first record of L. eliasoni in coastal waters off northern Norway. This species has been reported previously in the Skagerrak and Trondheimsfjorden (southern Norway), our findings therefore may indicate a northward extension of its range, possibly due to climate changes.

Based on material collected during the BIOICE project off Iceland, the taxonomy and distribution of seventeen species (11 genera) of polychaetous annelids belonging to the family Ampharetidae (Annelida; Polychaeta) is reviewed. Eleven of these species were previously reported in the area or nearby areas: Amage auricula , Anobothrus gracilis , Glyp− hanostomum pallescens , Grubianella klugei , Lysippe fragilis , L. labiata , L. sexcirrata , L. vanelli , Samythella elongata, Sosane bathyalis and S. wireni . Five species, Amage benhami, Melinnampharete eoa, Noanelia hartmanae , Ymerana pteropoda and Zatsepinia rittichae , either never or only once reported after original description, are redescribed or discussed. A potentially new species, Amage sp., is described but not named because only one specimen is present. Several body characters of high taxonomic relevance in Ampharetidae are reviewed using SEM. The distribution of each species off Iceland is provided.

The eight most abundant species (mean density >20 ind. m −2 ), which occurred at high frequencies (mean >30%) were selected from grab samples in the three Svalbard fjords: Hornsund, van Mijenfjord, and Kongsfjord, in the summer seasons between 1997 and 2007. Six polychaete and two bivalve species comprised more than 47% of the individuals and the biomass in all the samples examined. Four species are cosmopolitan, while the others are widely distributed Arctic−boreal species, and none has Arctic origin. Their density, frequency of occurrence, and biology are very similar across the wide geographical range from boreal to Arctic conditions. As the diversity of benthic fauna in the fjords studied increases (from 172 to 238 species), the dominance of the eight species in the soft bottom community diminishes from 76% to 47%. In times of hydrological regime shift, i.e. , the warming of the European Arctic, it is unlikely that the abundancy of these species in the soft bottom fjordic ecosystems will change. The most common soft bottom species are not good indicators of environmental change in the Arctic, and rare, specialized species are better option for indicative purposes.

By means of the synthetic diagram method (Romaniszyn 1970) populations of benthic Polychaeta at the depth ranging from 15 to 250 m of the Admiralty Bay (South Shetland Islands) were analysed. During the summer season of 1979/80 three replicate subsamples were taken at 18 stations situated along 3 crosssections using the Van Veen grab of a catching area of 0.09 m2 ; 61 benthic taxa of Polychaeta were recorded in these samples. The characteristics of particular assemblages are presented together with their tendency to change as a result of substrate quality, depth and position in the study area. Considerable affinity between the fauna of Polychaeta in the shallowest part of the bay and the composition and structure of polychaete assemblages occurring at Arthur Harbor (Anvers Island), which were described by Richardson and Hedgpeth (1977) was recorded.

Seventy−six species of Polychaeta were found in 19 quantitative samples collected in the deep sublittoral (200–500 m) of Admiralty Bay (South Shetlands). Three assemblages were distinguished by similarity analysis (clustering, nMDS). The soft bottom in depths from 200 to 300m was strongly dominated by Maldane sarsi antarctica and had very low species richness and diversity. The second assemblage was distinguished in the areas of the sea floor in the same depth range but with aggregations of Ascidiacea and Bryozoa. It was again characterized by high abundance of Maldane sarsi antarctica , but showed significantly higher species richness and diversity. Diversity of polychaete feeding guilds was also high in these areas. This pattern was probably associated with an increased habitat complexity due to the presence of dense aggregations of large suspension feeders. High species richness and diversity was also noted in the third assemblage, associated with the deepest sublittoral (400–500 m) of Admiralty Bay. This is the area characterized by very stable environmental conditions, where the assemblage was dominated by Tharyx cincinnatus , Sternaspis sp., Maldane sarsi antarctica , and Asychis amphiglypta .

226 taxa (180 identified to species) of benthic invertebrates are recorded from Admiralty Bay on the basis of the material collected by Polish Antarctic Expeditions. Main groups concerned are Folychaeta, Mollusca, Amphipoda and Echinodermata. For each species the bathymetric range, the frequency, the abundance and the geographical distribution are given.