INFESTATION OF PSEUDIONE TUBERCULATA (ISOPODA: BOPYRIDAE) ON JUVENILES OF LITHODES SANTOLLA (MAGELLAN REGION, CHILE): A SPATIAL MESOSCALE ANALYSIS

Abstract

We document latitudinal patterns of infestation of the bopyrid isopod parasite Pseudione tuberculata on southern king crab Lithodes santolla juveniles (20 – 50 mm carapace length) recruited to fishing grounds in the southern Chilean fjord system. A total of 750 individuals were collected by semiautonomous diving in 11 of 21 sampling locations in the study area along the western margin of the Magellan region between August and September 2013. The prevalence of P. tuberculata varied between 0 and ~22% and displayed a spatial pattern associated with three areas: i) northern Beagle Channel (10 – ~22%; lengths between 37 and 47 mm), ii) northeastern Navarino Island without infestations (0%; 26 – 55 mm) and iii) Piazzi Island – Capitan Aracena Island (0 – 12%; 50 – 77 mm). Infestations were independent of host sex, while parasite prevalence decreased with host length. Thus no parasitization was observed on crabs longer than 55 mm. A comparison of slopes between linearized length-weight regressions suggests that parasitized individuals had lower weight growth than uninfested individuals. Both southern king crab juvenile density and P. tuberculata prevalence were higher to the southeast of fishing areas towards Beagle Channel where previous research reported lower average surface water temperatures ( 30 psu). The study area covers four zones relevant for the conservation and protection of subantarctic biodiversity and provides opportunities for large-scale geographic studies of the host-parasite relationship.