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

Abstract

Background: 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. Results: 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. Conclusions: 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.

SIZE AT SEXUAL MATURITY OF NIPA-OBLIGATE CRAB Labuanium politum (CRUSTACEA: SESARMIDAE); HARVESTING PLAN PRECEDING COMMERCIALISATION

“…In terms of CW sizes, both male and female L. politum were evenly sized at earlier stages of gonadal development (IM and INT A). Dvoretsky and Dvoretsky, (2014) on red king crab Paralithodes camtschaticus suggested that at the earlier stages, sizes were the same between both males and females until reproductive age but in a recent study both male and female L. politum were showing significant differences in size after reaching INT B and DE stages. This study showed females were to be bigger than males after reaching INT B stage and this might due to the extension from gonadal development and external surface for carrying eggs on the abdominal pleopods which means larger berried female crabs with greater volume of eggs as being observed in Liocarcinus depurator (Rufino et al, 2004).…”

“…In crustaceans, the size between males and females might be different after reaching maturity. This might due to the sexual dimorphism, competition for mate and territory (Christy, 1987;Saher & Qureshi, 2012;Dvoretsky & Dvoretsky, 2014). Whilst, another null hypothesis had been raised concerning the size of males and females L. politum after reaching maturity; H 0 = Size between males and females L. politum after passing juvenile stage are equal.…”

Commercial fish and shellfish in the Barents Sea: Have introduced crab species affected the population trajectories of commercial fish?

“…(Hydrozoa), and Circeis armoricana (Polychaeta). Symbiotic species include Ischyrocerus commensalis and I. anguipes (Amphipoda), Tisbe furcata (Copepoda), Harmothoe imbricata (Polychaeta), and Johanssonia arctica (Hirudinea) (Dvoretsky and Dvoretsky 2009a, 2010a, 2013a. All species found on the crabs appear to be native to the Barents Sea (Dvoretsky and Dvoretsky 2009b, c).…”

Caprella ungulina Mayer, 1903 (Amphipoda: Caprellidae): epizoo de Paralomis granulosa (Hombron & Jacquinot, 1846) (Decapoda: Lithodidae) en aguas de Magallanes, Chile

“…El porcentaje de epibiosis fue estimado contabilizando el número de centollones con presencia del anfípodo, además de determinar el número de anfípodos presentes en cada ejemplar (Tabla 1). Estos índices son equivalentes al porcentaje de prevalencia (proporción de P. granulosa con epibiosis) y la intensidad (número de C. ungulina presente en cada ejemplar de centollón) (Bush et al 1997;Dvoretsky & Dvoretsky, 2013). …”

“…El porcentaje de epibiosis determinado en el presente estudio es bajo dado que menos del 15% de los ejemplares de P. granulosa analizados mostró epibiosis por parte de C. ungulina (Tabla 1), tomando en consideración el tamaño muestreal y que en otras especies de litódidos introducidos al Mar de Barents (Paralithodes camtschaticus), algunos anfípodos invasores (género Ischyrocerus) muestran niveles de prevalencia sobre el 40% (Dvoretsky & Dvoretsky, 2010) y en especies de copépodos harpacticoídeos comensales muestran valores superiores al 20% de prevalencia en el sistema branquial (Dvoretsky & Dvoretsky, 2013). Dada la captura de sólo ejemplares machos no se puede predecir qué niveles de epibiosis podrían ser comunes en ejemplares de P. granulosa de sexo femenino.…”