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, Madia/us modiolus, Arctica islandica, Littorina littorea and Zirphaea crispata. These arc now extinct in Svalbard; Zirphaea crispata, especially, requires considerable higher water temperatures than occur there today. Known radiocarbon dates on Mytilus, Modiolus and Zirphata arc 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 edu/is 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.

Radiocarbon-datedMytilus edulisandModiolus modiolusfrom northern Svalbard: Climatic implications

“…Since this is a thermophilous mollusc and not included in the present fauna of Svalbard, the palaeoclimatic implications of its former occurrence have been broadly discussed (see Feyling-Hanssen 1955, Salvigsen et al 1992, Hjort et al 1995.…”

“…After the introduction of the radiocarbon method for age determination, the number of dated samples of shells steadily grew, and 34 dates on Mytilus edulis from Svalbard were presented in Salvigsen et al (1992). Most of them were from the west coast and the central fjord areas of Spitsbergen, showing that Mytilus edulis lived there from before 9500 yr BP to c. 3500 yr BP.…”

“…Only three dates, all >9000 yr BP, were from the northern coast of Svalbard. Salvigsen et al (1992) also presented three radiocarbon dates on shells of Modiolus modiolus (horse mussel) from the shores of Isfjorden, with ages from c. 8700 yr BP to 7700 yr BP which were supposed to indicate a marine climatic optimum in this period. Hjort et al (1995) presented 11 age determinations on Mytilus edulis from Edgeøya and one such date from Svenskøya, Kong Karls Land.…”

“…The purpose of this paper is to follow up the information given in Salvigsen et al (1992) and Hjort et al (1995) and discuss further the matters dealt with there. The paper shows our present knowledge about the Holocene distribution of Mytilus edulis and Modiolus modiolus in northern Svalbard.…”

Ecological Shifts along the Florida Reef Tract: The Past as a Key to the Future

“…Stable oxygenisotopic values recorded in sediments from the extratropical North Atlantic also indicate warmer-than-present SSTs during the mid-Holocene (Ruddiman and Mix 1991). Evidence from both terrestrial and coastal regions shows that warming during this interval allowed many organisms to increase their ranges northward (Clarke et al 1967;COHMAP 1988;Delcourt and Delcourt 1991;Pielou 1991;Salvigsen, Forman, and Miller 1992;Dyke, Dale, and McNelly 1996;Strasser 1999;Dahlgren, Weinberg, and Halanych 2000;Jackson and Overpeck 2000). This period of thermal optimum during the Holocene also correlates with the northernmost position and expansion of coral reefs in the Pacific (Taira 1979;Veron 1992).…”