Aggregation patterns in juvenile southern king crab Lithodes santolla (Molina, 1782). Are the aggregations related to moulting activity?

ABSTRACTThe early life history of decapod species involves several stages and ontogeny-related shifts in habitat requirements and behaviour. Early publications have reported that, in the San Jorge Gulf (45–47°S), Argentina, juvenile southern king crab Lithodes santolla (Molina, 1782) (SKC) remain in rocky coastal habitats for at least three years, prior to their migration to soft bottoms. In this study, we analysed the gregarious behaviour of juvenile SKCs and its relation with moulting activity through the early ontogeny of the species. Different aggregation patterns were observed in SKC juveniles during sampling. These aggregation patterns were related to an increase in moulting activity. SKC 1+ and 2+ formed small groups of 7–31 juveniles in holes or cracks at shallower depths. A large aggregation was recorded in November 2014 associated with Macrocystis pyrifera forests. This aggregation involved advanced juveniles 3+, probably at the end of their stay in the coastal environment. Our results suggest that the aggregation of juvenile SKCs is related to high moulting activity and that differences in the aggregation patterns are related to ontogeny. The aggregation of advanced juveniles may reflect a (re)synchronous moult prior to a coordinated abandonment of the coastal environment.HIGHLIGHTS The aggregation behaviour of SKC juveniles is related to an increase in moulting activity.The aggregation pattern exhibits differences related to the size/age of SKC juveniles.SKCs form large aggregations at the end of their stay in coastal environments.KEYWORDS: Southern king crabLithodes santollaaggregations of juvenilesontogenetic shiftsmoulting activity AcknowledgementsWe thank Héctor Durbas for his assistance in the fieldwork.Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis work was partially funded by the Ministerio de Ciencia, Tecnología e Innovación Productiva of Argentina (PICT 2015-1297).