The incidence ofCarcinonemertes carcinophila(Kolliker) on some decapod crustaceans from the Scottish West Coast

Publisher Website
Google Scholar
Abstract
From May 1985 until June 1987, decapod crustaceans in the Firth of Lome were caught monthly by creeling. Ovigerous animals were preserved, and the gills and egg masses examined for evidence of infestation by the nemertean parasite Carcinonemertes carcinophila. Samples of the gills from male and non-ovigerous female crabs were also retained, and examined for the encysted juvenile stage. In the early months of 1989, a few ovigerous Carcinus mamas obtained by diving were examined. Ovigerous Liocarcinus puber and L. depurator were caught in small numbers, and both were infested with the parasite. In L. depurator the gills were heavily infested with the encysted juveniles, but few worms were found in the egg mass, 7 being the highest number in a single crab. In L. puber up to 25 worms were found in an individual crab, but the number of cysts in the gills was low. Only one ovigerous C. mamas was obtained by creeling; the egg mass contained only a few nernertines, and very few cysts were found on the gills. However, of the few shore crabs obtained by diving, one had the highest number offree-living worms found on an egg mass (42), but again very few cysts were found on the gills. Examination of the gills from male and non-ovigerous female crabs confirmed that C. mamas and L. puber had few identifiable encysted juveniles, whereas L. depurator had a very high number. No evidence of infestation was found in either the squat lobster Munida rugosa or the spider crab Hyas araneus, both of which were caught in considerable numbers. The egg strings of the parasite were found from May to October, associated with worms at least 13.6 mm long, although larger worms were found during the winter months.