For the third time this spring, scientists and students of the two projects CLEOPATRA (“Climate effects on planktonic food quality and trophic transfer in Arctic marginal ice zones”) and “Ecological and ecotoxicological studies of ice amphipods”, both led by UNIS marine biologist Jørgen Berge, completed an extensive field sampling campaign in one of the most remote areas in Svalbard. The projects aim at understanding the timing and linkage of ecological key processes in seasonally ice covered marine ecosystems. The consequences of changes in light due to retreating and thinning of Arctic sea ice are of key interest.

Text: Eva Leu, Post Doc, Norwegian Polar Institute

Rijpfjorden on Nordaustlandet was chosen as a study site, since it represents a “true” Arctic fjord. This fjord is open only to the north and is influenced little by warm Atlantic water masses transported along the West coast of Spitsbergen. Heavy sea ice prevails until June/July in this area. In previous years, UNIS cruises have visited this fjord and taken one transect of samples, usually in August/September. Apart from these ‘snapshots’ of an early autumn situation, no data about the marine ecosystem have been available until today.

The Rijpfjorden camp site, one of the most remote areas in Svalbard. (Photo: Janne Søreide).

All year round data collection
In autumn 2006, a mooring was placed in Rijpfjorden to provide a continuous year-round data series about hydrographical and biological features of the fjord that will serve as important background information for the seasonal study performed in 2007.

In early February 2007, a weather station and a webcam were established there in order to monitor the meteorological conditions and ice cover.

During the four field campaigns this spring/summer (March, April, June and July 2007), biological data about ice algae, phytoplankton, zooplankton, sympagic and benthic amphipods, as well as light profiles and CTD measurements, are obtained.

Further data will be collected during the autumn cruises in August, September and October 2007. Despite major logistic challenges and pretty rough weather conditions (at least during the first stay in March), the three expeditions so far are a great success.

Delayed reproduction in the east
Rijpfjorden became completely ice-covered by land-fast ice during February, and the ice thickness had reached 50-70 cm in early March. The ice was growing further up to 80-100 cm in mid-April, and increased even a little bit more until mid-June. Light conditions, however, were changing greatly during the same period, owing to changes in the solar angle and snow depth.

The biomass of primary producers differed correspondingly. Zooplankton was found close to the ice, obviously feeding on ice algae, judging from their green gut and the absence of algae in the waters below the ice. Their reproduction, however, seemed to be delayed compared to fjords on the west coast. Benthic amphipods were also found close to the sea ice showing the importance of the production in the ice. Despite a lack of multi-year sea ice in the area, great numbers of truly ice associated amphipods were found in the inner basin of the fjord.

Students and scientists collecting data from the sea ice. (Photo: Jørgen Berge).