The algal vegetation in the outer part of Isfjorden, Spitsbergen: revisiting Per Svendsen's sites 50 years later

The benthic algal vegetation was investigated at two different sites in the outer part of Isfjorden, Svalbard, during 27–29 July 2007. One exposed site at Kapp Linné and one sheltered site in Ymerbukta were sampled both in the littoral and sublittoral zones. A total of 83 different taxa were recorded, 81 from the sublittoral and 40 from the littoral zone. The sublittoral zones at the two sites did not differ much in terms of the taxa recorded, but the number of species in the littoral differed between the two sites: Kapp Linné had 39 while only five species were found in Ymerbukta. The results are compared to a survey made by Per Svendsen in 1954 and 1955 in order to seek any changes in the diversity. Even though the number of species is difficult to compare directly, we registered a higher species number than Svendsen did 50 years ago. The difference seemed more pronounced in the littoral zone than in the sublittoral. Possible explanations for the differences between the two investigations are discussed. Two species not previously recorded in Svalbard, Antithamnionella floccosa and Litosiphon laminariae, were registered.