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Kelp forests are complex underwater habitats that support diverse assemblages of animals ranging from sessile filter feeding invertebrates to fishes and marine mammals. In this study, the diversity of invertebrate fauna associated with kelp holdfasts was surveyed in a high Arctic glacial fjord (76 N, Hornsund, Svalbard). The effects of algal host identity (three kelp species: Laminaria digitata, Saccharina latissima and Alaria esculenta ), depth (5 and 10 m) and glacier-derived disturbance (three sites with varying levels of mineral sedimentation) on faunal species richness and composition were studied based on 239 collected algal holdfasts. The species pool was mostly made up by three taxa: colonial Bryozoa and Hydrozoa, and Polychaeta. While the all-taxa species richness did not differ between depths, algal hosts and sites, the patterns varied when the two colonial sessile filter-feeding taxa were analysed alone (Hydrozoa and Bryozoa). The Hydrozoa sample species richness and average taxonomic distinctness were the highest at undisturbed sites, whereas Bryozoa species richness was higher in sediment-impacted localities, indicating relative insensitivity of this phylum to the increased level of mineral suspension in the water column. The average taxonomic distinctness of Bryozoa did not vary between sites. The species composition of kelp-associated fauna varied between sites and depths for the whole community and the most dominant taxa (Bryozoa, Hydrozoa). The high load of inorganic suspension and sedimentation did not cause pauperization of kelp holdfast-associated fauna but instead triggered the changes in species composition and shifts between dominant taxonomic groups. [ABSTRACT FROM AUTHOR]

Hydroid diversity and species composition were studied in Arctic coastal waters around the Norwegian Svalbard Archipelago. The aim of the present study was to examine the influence of physical factors (depth and substrate type) on the distribution and diversity of the benthic hydrozoan fauna that has been poorly studied in the high-latitude polar region. The study is based on a total of 557 samples collected between 1996 and 2007. Over 1200 colonies and 70 taxa of Hydrozoa were collected by SCUBA divers, dredges and van Veen grabs. The distribution patterns with respect to major environmental factors were studied based on presence/absence data. Four substrate types were most commonly colonized by hydroid colonies: algae, bryozoans, rocks and hydrozoans. The highest species richness was noted on algae and rocks. Shallow water communities of the study area were characterized by a high hydroid species richness. A number of species decrease along the depth gradient. Some species have shown some preferences towards selected substrates or one of the two depth zones, but most hydroid species were generalists in terms of both the depth and substrate preferences. No species could be classified as substrate-specific ( i.e. occurring only on one substrate type). The substrate heterogeneity was shown to be an important driver of hydroid species richness in Arctic coastal waters. [ABSTRACT FROM AUTHOR]

High polar communities tend to be young because of the frequent and intense impact of ice (scour), so colonisation patterns are particularly important. Yet, despite a wealth of studies at temperate and tropical latitudes, we know of no hard substratum settlement/colonisation experiments reported north of 60°N, to date. Here we report on fauna encrusting square panels immersed at 12 m depth in Isforden, Spitsbergen (Svalbard) after 2 and 3 days, a week and a year. Arctic colonisation is slow but is not species poor. We found no colonists present after 2 and 3 days but two panels were colonised by a bryozoan and polychaetes after a week. After a year immersion, three panels were 3, 5 and 11% covered with a mean of ∼247 colonists. This is about an order of magnitude lower than has been described from most studies elsewhere, but not as low as has been recorded at an Antarctic locality. Most individual colonists (80–93%) were polychaetes ( Spirorbis tridentatus) but most of the species were bryozoans. The Arctic is widely described as taxon poor compared with elsewhere, but at the local scale we investigated, species richness (20) was as high or higher than in many similar colonisation studies along the north Pacific or Atlantic coasts. In striking contrast, no settlement panel study has yielded fewer higher taxa (2 phyla, 3 classes) than this high arctic study. [ABSTRACT FROM AUTHOR]

Thirty-two species of echinoderms from epibenthic sledges, dredges, scuba diving, and other samples (in total: 467 samples and c. 20 000 specimens) from fjords and coastal waters off Spitsbergen were analysed between 1996 and 2014. The most numerous group of echinoderms in the coastal waters off Spitsbergen is brittle stars (78% of the total individuals). The echinoderms do not form any clear assemblages according to depth or distance from glacial sedimentation and substrate. Some species prefer hard bottom ( Strongylocentrotus droebachiensis) or water free from glacial suspensions ( Ophiopholis aculeata). In contrast to the species listed above, we also found opportunistic species such as the starfish Urasterias lincki and the brittle star Ophiocten sericeum. These two species are distributed quite uniformly, regardless of the environmental factors. The majority of the species prefer a soft bottom below 200 m. [ABSTRACT FROM AUTHOR]