The Davis Strait - DCE - Nationalt Center for Miljø og Energi

84
due to the technical difficulties of quantitative sampling on hard or mixed
substrates. As a consequence, our knowledge about the benthic communities
associated with such heterogeneous habitats is limited, despite the fact that
such habitats are widespread in coastal areas in Greenland. A specific taxon
that is receiving increasing attention is cold-water corals. These corals are
widespread in large parts of the north Atlantic where they create a unique
habitat that is inhabited by a specific fauna (Mortensen & Buhl-Mortensen
2004, Bryan & Metaxas 2006). Cold water corals have been found in the
western part of the Davis Strait (Edinger et al. 2007). In Greenland waters
knowledge of coral distribution and abundance has not been systematically
studied. However, during trawl surveys conducted in Greenland waters,
corals have been found at many locations along the continental slope of
Southwest- and Southeast Greenland (ICES 2010a). Recently, a ban against
trawling in two areas south of Maniitsoq (64°N) was suggested due to the
observations of high abundance of corals.
4.5 Sea ice community
Susse Wegeberg (AU)
At least part of the assessment area is considered an open water region, so
sea ice and thereby sea ice communities may be less important in the area
compared with in areas with more extensive sea ice cover north of the assessment
area. However, in most winters the western part of the assessment
area is covered with pack ice from the Canadian side (Fig. 3.3.2) and sea ice
also occurs regularly in the fjords of the assessment area. Thus, the production
of these ice communities may be of greater importance in some years, at
times when the pelagic and benthic productions are relatively low, especially
before the spring bloom of phytoplankton. In addition, the sea ice community
is expected to be very vulnerable to oil spills as the ice may catch
and accumulate oil in the interface between ice and sea and the oil may penetrate
the ice through brine channels, and both these areas represent the
spaces occupied by sea ice communities.
The sea ice in the assessment area may be habitat for a specialised ecosystem
of bacteria as well as many species of microalgae and microfauna. Within
the assessment area, in the fjord Kangerluarsunnguaq (Kobbefjord), just
south of Nuuk, Mikkelsen et al. (2008) found that flagellates (prasinophytes,
dinoflagellates, cryptophytes) and both centric and pennate diatoms were
regular components of the sea ice algal community. Of diatoms especially
Chaetoceros simplex, a colonial, centric diatom, was dominant (75% of total
sea ice algal abundance) during its bloom in March. In the pack ice on the
Canadian side of the Davis Strait, Booth (1984) found a total dominance of
pennate diatom genera.
Strong patchiness of the sea-ice algae is commonly reported in the Arctic
(Booth 1984, Gosselin et al. 1997, Gradinger et al. 1999, Rysgaard et al. 2001,
Quillfeldt et al. 2009), caused by heterogeneity of the ice. Changes in ice
thickness, crystalline structure, salinity, porosity and density are important
for the community structure of sea ice organisms. Sea ice environments are
highly dynamic and display large variations in temperature, salinity and nutrient
availability. These variations lead to the high degree of horizontal
patchiness in microbial sea ice communities (Quillfeldt et al. 2009).