High Arctic Mytilus spp.: occurrence, distribution and history of dispersal

Many marine species are known to change their distribution in response to changing climatic conditions. One such example is the blue mussel Mytilus spp., spreading northward coincident with an increase in ocean temperatures. On Svalbard, the frst living specimens of Mytilus spp. were discovered in 2004. Here we present an analysis of the current distribution of Mytilus spp. on Svalbard, with a focus on the west coast of Spitsbergen where strong Atlantifcation has been documented over the last few decades. We conducted diver-based surveys to develop a distributional map and to compare the current distribution with that of the Holocene. Furthermore, we investigate the recent history of recruitment of mussels on Svalbard to help identify invasion pathways. Our results show that blue mussels have been present on the archipelago at least since 2000 and are widespread along the west coast today. We also present evidence of local reproduction in one of the sites explored