Finlo Cottier

This is chapter 1 of the State of Environmental Science in Svalbard (SESS) report 2021. We show temperature records from five marine observatories located around the fjords of Svalbard – Kongsfjorden (3 observatories), Isfjorden and Rijpfjorden. We have analysed the records from these observatories (the shortest is 5 years, the longest is 18 years) to determine trends in the water temperature. We investigated trends in the warmest part of the year (September to November) and the coldest part (March to May). In those fjords facing west towards the Fram Strait we typically see increasing temperatures, the maximum rate being 1.5°C per decade for the coldest period of the year in Kongsfjorden. This has resulted in much less sea ice in these western fjords. In the far northeast, Rijpfjorden shows no signs of warming at any point in the year. We also investigated the salinity of the bottom water in the outer part of Kongsfjorden and show that the salinity peaks in October and that there i...

The changing Arctic environment is affecting zooplankton that support its abundant wildlife. We examined how these changes are influencing a key zooplankton species, Calanus finmarchicus, principally found in the North Atlantic but expatriated to the Arctic. Close to the ice-edge in the Fram Strait, we identified areas that, since the 1980s, are increasingly favourable to C. finmarchicus. Field-sampling revealed part of the population there to be capable of amassing enough reserves to overwinter. Early developmental stages were also present in early summer, suggesting successful local recruitment. This extension to suitable C. finmarchicus habitat is most likely facilitated by the long-term retreat of the ice-edge, allowing phytoplankton to bloom earlier and for longer and through higher temperatures increasing copepod developmental rates. The increased capacity for this species to complete its life-cycle and prosper in the Fram Strait can change community structure, with large cons...

We measured vertical migration of zooplankton in an arctic fjord at 79uN between June and September 2002 and transcending a period of continuous illumination to one of true day and night to investigate the changing influence of light cues on behavior. Observations made with a moored 300 kHz acoustic Doppler current profiler indicated that two modes of vertical migration occurred during the study period. During the weeks of continuous illumination, backscatter data indicated that there was no net vertical displacement of the population at any time during the 24-h period, but vertical velocity showed a continuous net downward movement in the surface layers and a net upward movement at depth. We interpreted this as unsynchronized vertical migrations by individuals with upward trajectories that slowed closer to the surface and downward trajectories that were most rapid in their initial phases. Synchronized migrations, seen as an upward and downward movement of scattering layers at dusk and dawn respectively, began once true nighttime resumed toward autumn. It is likely that the relative rate of change in light was used as the proximal cue for synchronized migrations. Concurrent net samples identified Calanus finmarchicus and C. glacialis as the most likely contributors to the unsynchronized migration patterns. The high backscatter of the synchronized scattering layers suggests that they included additional taxa such as the euphausiid Thysanoessa spp., the pteropod Limacina helicina, or the hyperiid amphipod Themisto spp

... [2006]. The isopycnal mixing is 19 dominantly the act of eddy activity, which over time will modify the density field towards terrain-20 following isopycnals, or flat isopycnals far from the bottom [Adcock and Marshall, 2000]. This 21 ...