Abstract
In order to predict the expansion of the golden mussel (Limnoperna fortunei) population in Lake Kasumigaura, Japan, we investigated its spatial distribution in 2012 and compared it to the distribution in 2006. In 2012, mussels were found in 104 (83.2%) of 125 sampling sites evenly spaced around the entire shoreline of the lake. No mussels were found near the mouth of the Koise River at the north end of the lake. On average, the mussel density (the number collected in 10 minutes by a single researcher) at a given site was 3.8 times higher in 2012 than in 2006. Colonization of a vacant site from the nearest inhabited site was explained primarily by distance, whereas habitat classification of a vacant site had no significant effect. There was a 50% probability that golden mussels would colonize a vacant site as distant as 10.96 km from the nearest inhabited site within six years. Given this colonization potential, we predict that golden mussels will spread over the entire shoreline by 2018 at the latest.
