International Polar Year 2007–2008 - WMO

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IPY 20 07–20 08
decrease in the Arctic watermass (Fig. 2.2-10).
Even though the biophysical model predicted
rather modest changes in the climate and plankton
production of the Barents Sea (Ellingsen et al., 2008),
these changes were nevertheless sufficient to produce
responses in capelin abundance, spawning area and
adult distribution.
New insights into temperature effects on the
distribution of capelin of the Barents Sea. The capelin
stock of the Barents Sea has long been recognized
as a principal food fish for cod and, therefore, as a
key component of the ecosystem on the Norwegian
arctic shelf. The importance of temperature as a
control on distribution of capelin has also long been
recognized, in general terms, but the specifics of that
relationship have now been examined in a study by
Randi Ingvaldsen, IMR Bergen. She finds that when the
temperature increases, the capelin spread northwards
and the distribution-area increases. When the capelin
stock is large, the feeding area is normally extended
eastwards. Consequently, the largest distribution
areas occur when the temperature is high and the
stock is large at the same time.
Complementing this study, Huse and Ellingsen
(2008) have modelled the likely consequences
of global warming on capelin distribution and
population dynamics. With input on physics and
plankton from a biophysical ocean model, the entire
life cycle of capelin including spawning of eggs, larval
drift and adult movement is simulated. The model
generates output on capelin migration/distribution
and population dynamics; simulations are performed
using both a present day climate and a future
climate scenario. For the present climate, the spatial
distributions resemble the typical spatial dynamics of
capelin, with the Murman and North Norway coasts as
the main spawning areas. Nevertheless, for the climate
change simulation, the capelin is predicted to shift
spawning eastwards and also utilize new spawning
areas along Novaya Zemlya. There is also a shift in the
adult distribution towards the north eastern part of
the Barents Sea and earlier spawning associated with
the warming. As the authors point out, it remains an
open question whether capelin will take up spawning
at Novaya Zemlya as predicted by the model, but
there is some evidence that such easterly spawning
has taken place in the past (see Gjøsæter, 1998).
The IPY in the NW Barents Sea. The Svalbard
archipelago in the NW Barents Sea is the eastern
gateway for Atlantic Water flowing into the Arctic.
Consequently the oceanography of the region
is characterized by the distinct water masses of
Atlantic or Polar origin, contrasting strongly in their
temperature and salinity. The sea ice conditions
around the archipelago reflect these contrasts, with
northern and eastern coasts having seasonal ice
cover while the west coast is relatively ice-free. Such
a range of conditions permits comparative studies of
ecosystem function to be conducted and has enabled
the investigation of the likely impact of warm, ice-free
conditions on arctic ecosystems (Willis et al., 2006) and
of how ecosystems might respond to changes in the
seasonal timing of retreat of the ice-edge.
Two sites in the archipelago have proved ideal for
such studies. Rijpfjorden, a fjord in Nordaustlandet
that faces north to the Arctic Ocean, represents the
Polar extreme while Kongsfjorden in NW Spitsbergen
is a site that is dominated by warm Atlantic Water with
water temperatures in excess of 6°C (Cottier et al.,
2007). The ice-covered nature of Rijpfjorden and the
relatively ice-free conditions in Kongsfjorden provide
a natural setting to investigate the role ice plays in
structuring arctic ecosystems. A key observational
capability is the placement of moored instruments
in each fjord, to provide background environmental
data or as a means of studying the shelf processes.
These moorings have been maintained by the Scottish
Association for Marine Science (www.arcticmarine.
org.uk) since 2002, with the logistical assistance of
Norwegian institutes, particularly University Centre in
Svalbard (www.unis.no).
The issue of ecosystem response to changes in sea
ice conditions have been captured in a Norwegian
IPY project called CLEOPATRA (Climate effects on
planktonic food quality and trophic transfer in Arctic
Marginal Ice Zones). CLEOPATRA was conducted in
Rijpfjorden which can be considered as a mesocosm
site representative of Arctic processes. The main
objectives of the IPY CLEOPATRA project were to study:
(1) the timing, quantity and quality of ice algal and
phytoplankton spring bloom;
(2) how variations in light and UV radiation affect
algal food quality; and
(3) the importance of timing and available food