Seasonality in an Arctic fjord ecosystem: Hornsund, Spitsbergen

Abstract

Based on two complete years of marine ecological surveys (1981‐82 and 1984‐85) carried out in the Hornsund fjord on southern Spitsbergen (77N), the seasonal variation of physical and biological processes is presented. Physical parameters reflect the strong seasonality of sun radiation, while water salinity and temperature fluctuate within a narrow range. Concentrations of nutrients and suspended matter depend on meltwater discharge from glaciers and snow cover thickness. The breeding period of most marine invertebrate species is strongly related to the phytoplankton bloom which peaks in May. Ringed seal and polar bear occurrences are directly related to sea ice conditions. Both species are most numerous in Hornsund during March‐April. Sea birds which nest in huge colonies along the Hornsund coasts arrive in April‐May and leave by August‐September except for Fulmars and Brünnich's Guillemots which were observed year‐round.

Scale-dependent variation in competitive ability among encrusting Arctic species

“…Winter fast-ice is less common and longer lived from the inner fjord to the mouth (Węs8awski et al 1988). Sea temperature in July was ~3°C in all areas (annual variation approximately -1.8 to + 4°C).…”

“…The near-bottom salinity regime is even more stable, varying from just 33 to 34 psu. At the surface and on the shore, salinity can change rapidly with the melt around June (32 to 25 psu; see Swerpel 1985, Węs8awski et al 1988). There is a substantial suite of potential competitors, except in the intertidal, which is characterised by a depauperate fauna (Węs8awski et al 1993, Kuklinski 2001).…”

Bipolar patterns of intraspecific competition in bryozoans

“…The central and outer parts of the fjord are only occasionally covered with fast-ice (Węs8awski et al 1988). Oceanographic and seasonal aspects of Horsunfjord have been covered in more detail by Swerpel (1985) and Węs8awski et al (1988). Similarly, for details of biomass, biodiversity and competition on the intertidal and coastal boulders see Węs8awski et al (1993) and Barnes & Kukliński (2003).…”

“…1). The sea temperature at the time of material collection in July 2002 was 3°C (annual variation -1.8 to 4°C), and salinity varied from 33 to 34 psu (but this can drop rapidly during the June melt to > 25 psu, see Swerpel 1985 andWęs8awski et al 1988). The inner fjord is characterised by winter (mid-December to end of May) coverage of fast-ice (frozen sea surface) and is subject to ice scour from floating ice during summer months.…”

“…The inner fjord is characterised by winter (mid-December to end of May) coverage of fast-ice (frozen sea surface) and is subject to ice scour from floating ice during summer months. The central and outer parts of the fjord are only occasionally covered with fast-ice (Węs8awski et al 1988). Oceanographic and seasonal aspects of Horsunfjord have been covered in more detail by Swerpel (1985) and Węs8awski et al (1988).…”