Biodiversity on coastal boulders at Spitsbergen

Boulder communities were studied in summer 2002 in West Spitsbergen fiords. We examined multiple samples at three stations in Kongsfjorden (79° N, 12° E) and three stations in Hornsund (77° N, 16° E) fjord. Horsund is more influenced by Arctic water masses while Kongsfjorden is by Atlantic warmer waters. Altogether 2752 boulders (of 254 681 cm2 surface area) were investigated in the intertidal, 6 m and 12 m. 73 taxa of Bryozoa were determined; 1 to phylum, 1 to order, 3 to family, 16 to genus and 52 to species level. ANOSIM a priori statistic (Global R=0.141, p=0.016) reveal no difference between the investigated sites. Cluster and multidimensional scaling analyses divided samples into two groups: intertidal samples and the rest of samples. Thirteen taxa (8 species) occurred in the intertidal zone whilst 73 taxa (52 species) were subtidal. All the intertidal taxa were also present in the subtidal samples. Communities were dominated by Harmeria scutulata (57% in of colonies in the intertidal and 54% in the subtidal). The next most abundant species, Cauloramphus intermedius and Cribrilina annulata represented just 5% of colonies each; the dominance values for the other taxa were below 5%. There was no diversity pattern along the depth gradient. In both fjords the highest values of Shannon-Wiener index were 2.7. Despite the distance between Kongsfjorden and Hornsund (over 200 km) and differences in hydrological features between the fjords no difference between their boulder communities.