Abstract
The main aim of this study was to compare the polychaete communities in two similar polar areas: an Arctic fjord, Hornsund (Svalbard) and an Antarctic fjord, Ezcurra Inlet (South Shetlands). This is the first attempt to compare Arctic and Antarctic diversity based on fully comparable datasets. Forty van Veen grab samples were collected in each fjord: twenty replicates were taken in each of two fjord areas characterized by a different level of glacial disturbance—in the inner (glacial bay) and outer (fjord mouth) region of both fjords, from depths of about 100 m in 2005 (Hornsund) and in 2007 (Ezcurra Inlet). In the glacial bays, species richness and diversity were significantly higher in Ezcurra Inlet than in Hornsund due to higher rate of glacial disturbance in the latter one. In the outer areas, species richness was similar in both fjords, although diversity values were higher in Ezcurra Inlet. Polychaete species richness in the habitats characterized by similar level of disturbance (outer areas of the fjords) was the same in both polar regions. At this small scale, where community drivers are very similar, the species richness seems to be independent from the local or regional species pool.
Highlights
Until recently, it was commonly assumed that the benthic diversity in the Antarctic is substantially higher than in the Arctic (Dayton et al, 1994; Knox & Lowry, 1977; Crame, 1997; Brandt, 2001)
Forty van Veen grab samples were collected in each fjord: twenty replicates were taken in each of two fjord areas characterized by a different level of glacial disturbance—in the inner and outer region of both fjords, from depths of about 100 m in 2005 (Hornsund) and in 2007 (Ezcurra Inlet)
23,103 specimens were collected in Hornsund (HD), and 24,121 in Ezcurra Inlet (EI) (Table 2)
Summary
It was commonly assumed that the benthic diversity in the Antarctic is substantially higher than in the Arctic (Dayton et al, 1994; Knox & Lowry, 1977; Crame, 1997; Brandt, 2001). The homogeneity of the Arctic benthic habitats and higher rates of disturbance were pointed as possible reasons for differences in diversity between both regions (Dayton, 1990) These common assumptions have recently been questioned and considered as a result of overgeneralization (Piepenburg, 2005). There have only been few attempts to compare benthic diversity on Arctic and Antarctic shelves, and those included only large scale syntheses comparing either the Arctic and Antarctic as a whole (Knox & Lowry, 1977), or large basins, like the Laptev Sea and Weddell Sea (Piepenburg et al, 1997; Starmans et al, 1999; Starmans & Gutt, 2002; Sirenko, 2009) Those analyses were mostly focused on mega-epibenthic fauna, not always collected with quantitative sampling gear. Rigorous comparisons of similar depths and types of habitats are essential as the only way to provide any further meaningful inventories (Clarke & Crame, 2010)
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