Thermophilous molluscs on Svalbard during the Holocene and their paleoclimatic implications

Abstract

Five species of guide fossils from the Holocene warm period in Svalbard are considered: Mytilus edulis, Modiolus modiolus, Arctica islandica, Littorina littorea and Zirphaea crispata. These are now extinct in Svalbard; Zirphaea crispata, especially, requires considerable higher water temperatures than occur there today. Known radiocarbon dates on Mytilus, Modiolus and Zirphala are given. Thirty-four dates on Mytilus edulis show that it lived in Svalbard from before 9500 BP to about 3500 BP, and probably again around 1000 BP. Five dates on Modiolus and Zirphaea indicate a climatic optimum in Svalbard from about 8700 BP to 7700 BP. The most favourable places then had conditions similar to the northeastern coast of Finnmark, northernmost Norway, today. Mytilus edulis is considered a good climate indicator, and a future warming of the marine climate in Svalbard could be indicated by its eventual re-immigration into the area.