Pelagic Amphipoda in a warming Arctic Ocean
The order Amphipoda is a widespread and abundant group in marine, freshwater, terrestrial and ice-associated habitats. They belong to the superorder Peracarida, which also includes zooplankter like cumaceans and isopods. In total, peracarids make up approximately 40 % of all crustaceans worldwide and often exceed the other crustacean taxa in terms of numbers and diversity. The order Amphipoda is a multifaceted group with about 7000 species in 150 families - comprised of the four suborders Caprellidea, Gammaroidea, Hyperiidea and Ingolfiellidea.
In the Arctic, about 15 amphipod species have been observed living underneath the sea-ice or in the open water. In this region, free-swimming Amphipods are important components in the ecosystem. The biomass of Themisto libellula in ice-free waters of the Greenland Sea and the northern North Atlantic has been estimated at 100 million tons. A order of magnitude comparable with the Antarctic krill in the Southern Ocean. T. libellula plays a central role in Arctic pelagic food webs. They provide a direct link between herbivore zooplankton such as copepods and higher trophic levels such as sea-birds, fish and marine mammals. Nowadays, in the Arctic organisms are faced with a drastically changing environment including increasing ocean temperatures and acidification as well as a rapidly declining sea ice cover. However, the seasonal distribution of amphipods in ice-covered Arctic seas, as well as many ecological features are still poorly understood.
Ongoing research
In the Arctic long-term observatory HAUSGARTEN (79°N/4°E) in the eastern Fram Strait we study species composition of Amphipods, their year-round distribution patterns and the influences of changing water temperature and sea ice properties on their community. In respect to this project, a co-operation between the AWI and two partners, the Norwegian Polar Institute and the Arctic Marine Ecosystem Research Network, both located in Tromsø, Norway, was established.
