Epifauna associated with an introduced crab in the Barents Sea: a 5-year study

Species composition, prevalence, intensity, and spatial distribution of macro-invertebrates colonizing the invasive red king crab (Paralithodes camtschaticus) in a typical bay of the Barents Sea, Dalnezelenetskaya Bay (depths 5-40 m), and adjacent deeper water (120-180 m) were examined in the summers of 2004-2008. In all, 43 associated species were found on the crabs. The most common epibionts were Mytilus edulis (Bivalvia), Obelia spp. (Hydrozoa), and Circeis armoricana (Polychaeta). Symbiotic species included Ischyrocerus commensalis and Ischyrocerus anguipes (Amphipoda), Harmothoe imbricata (Polychaeta), and Johanssonia arctica (Hirudinea). There were no significant differences in the prevalence of infestation between male and female crabs. The prevalence of most of the common species was greater in crabs with old shells than in crabs with new shells. Infestation levels of J. arctica were higher in deeper than in shallow water, and M. edulis was less abundant in deep water. All species found on the crabs appear to be native to the Barents Sea. However, I. commensalis amphipods were not found at the site examined before the introduction of the red king crab, indicating that their distribution may have changed after association with this host species. Introduced hosts may well influence the distribution of rare native species.