RESEARCH/REVIEW ARTICLE 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. The marine benthic algal vegetation on Spitsbergen is relatively poorly studied. Lindblom (1839) drew up the very first list: 19 species. During the second half of the 1800s, Agardh (1862; 1868) studied samples from several Swedish expeditions and increased the total number of species from Spitsbergen to 51. When Kjellman participated in the Swedish polar expedition from July 1872 through August 1873, he studied the algal vegetation on the western and northern side of the island of Spitsbergen. An unplanned overwintering in Mosselbay, northern Spitsbergen, allowed Kjellman to sample benthic algae under the ice during the winter and to observe that algae grew and reproduced ther