Copepods associated with the red king crab Paralithodes camtschaticus (Tilesius, 1815) in the Barents Sea

Abstract

There are no data on copepod occurrence, infestation indices, and localization on red king crabs in the Russian part of the Barents Sea. For this reason, we examined the species composition, infestation indices, and localization patterns of copepods colonizing the red king crab Paralithodes camtschaticus in Dalnezelenetskaya Bay, a small gulf in the Barents Sea. In total, nine species of Copepoda were found on hosts in July of 2009 ~ 2011. Typical planktonic copepods (Calanus, Microsetella, and Microcalanus) and some benthopelagic and benthic species (Ectinosoma, Cyclopina, and Zaus) were found in low occurrences; their prevalences did not exceed 5%, and these copepods should be considered incidental visitors. The benthopelagic harpacticoid copepods Tisbe, Harpacticus, and Dactylopusia were the most abundant, with high prevalences and mean intensities of infestation, and should be classified as commensals. Infestation indices were correlated with the host size and shell condition. The majority of copepods were found on host gills (90% ~ 100%). We suggest that the recorded absence of symbiotic copepods from crab branchial chambers in our previous studies in August of 2004 ~ 2008 may be explained by predation or competition with the symbiotic amphipod Ischyrocerus commensalis, which was confirmed by analysis of amphipod gut contents. This report expands our knowledge on the colonization of different fouling and symbiotic species on red king crabs. Our study has management and aquaculture implications as it sheds light on possible interactions between copepods and their crab hosts. Colonization of crabs in general may be beneficial for the copepod species because it enhances food acquisition, increases their mobility, and affords them a degree of protection from predators. Conversely, this association may have negative effects on the crab host due to a decrease in respiratory function.