New Records of Symbiotic Amphipods on Red King Crabs in the Coastal Barents Sea.

Monitoring epibiotic communities on the invasive red king crab (Paralithodes camtschaticus) in the Barents Sea is crucial for understanding the co-adaptation between this species and the local benthic fauna. Red king crabs were collected during regular diving surveys conducted in the coastal Barents Sea in 2015, 2021, and 2022. A detailed examination revealed the presence of two amphipod species, Metopa pusilla and Crassicorophium bonellii, which were not previously documented as epibionts on this host. With these additions, the total number of epibiotic amphipods on Barents Sea red king crabs rises to nine species (versus two in the native Sea of Okhotsk). Amphipod colonization was skewed toward large males, likely reflecting their greater migratory behavior. The prevalence of Metopa pusilla ranged from 1.9% to 4.3%, with a mean intensity of one individual per infested crab; Crassicorophium bonellii exhibited prevalence of 4.7-14.3% and mean intensity of 1.3-3.3 individuals. The primary colonization sites were the carapace and limbs. Given the low infestation parameters and the epibionts' localization away from critical structures like the gills and egg clutches, it is concluded that these amphipods pose a negligible risk to host health.