Prey Selectivity in Juvenile Red King Crabs from the Coastal Barents Sea

Abstract

The invasive red king crab, Paralithodes camtschaticus, has become an abundant and important component in the food web of the coastal Barents Sea and can affect the structure and functioning of the local benthic communities through competition and predation. Although dietary composition and feeding behavior of the crab have been intensively studied, prey selectivity in this species under natural conditions remains poorly defined. For this reason, juvenile red king crabs and benthic samples were collected simultaneously at five coastal sites in Kola Bay to reveal the species composition and structure of feeding habits and the diet of red king crabs. The results of stomach and gut content analyses coupled with calculated Ivlev’s indices indicated that 2–5-year-old crabs frequently consumed bivalve mollusks in relative proportions to prey field biomasses. At all sites, juveniles selectively rejected polychaetes. In soft-bottom communities, when the average density of Bivalvia decreased, the crabs showed increased preference for Gastropoda, Crustacea, and Echinodermata. As a result of selective feeding focused on infaunal suspension-feeding mollusks, juvenile red king crabs have altered the structure of benthic communities in the mouth of Kola Bay. Our results may have important implications for evaluating the consequences of the crab introduction and its population management.

Ecology and Distribution of Red King Crab Larvae in the Barents Sea: A Review

“…In autumn, RKC individuals segregate by sex, and males and females form aggregations in deep and shallow waters, respectively [24,25,27]. RKC is a high-level predator feeding on abundant bottom animals including mollusks, polychaetes, and echinoderms [44]. They can also feed on fish offal in the regions where multispecies fishing occurs [44,65].…”

“…RKC is a high-level predator feeding on abundant bottom animals including mollusks, polychaetes, and echinoderms [44]. They can also feed on fish offal in the regions where multispecies fishing occurs [44,65]. The main predators of RKC are cod, wolffish, and skates [24,25,27,29].…”

“…The benthic fauna represents an important component of the Arctic marine food webs and bottom secondary production was found to contribute a significant part to the diet of commercial demersal fish [43]. As RKC is a top predator it may compete with benthivorous fish and benthic organisms for food [44]. Some authors reported reduced benthic diversity and biomass at some coastal sites after the RKC introduction [40,44].…”

“…As RKC is a top predator it may compete with benthivorous fish and benthic organisms for food [44]. Some authors reported reduced benthic diversity and biomass at some coastal sites after the RKC introduction [40,44]. Furthermore, this species has become a host for a variety of epibiotic and symbiotic species [32,33,40,45] promoting their range expansion and possible cascading impacts on the ecosystem [33].…”

“…Many aspects of the RKC biology, ecology, fisheries, aquaculture, and management have been intensively studied and reviewed [23][24][25]27,[29][30][31][32][33][34][35]41,42,[44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63]. The larvae of RKC exist during the spring period and they occur in the plankton during 8-10 weeks and then settle to the bottom [29].…”