INFECTION OF THE NORWAY LOBSTER NEPHROPS-NORVEGICUS BY A HEMATODINIUM-LIKE SPECIES OF DINOFLAGELLATE ON THE WEST-COAST OF SCOTLAND

Nephrops norvegicus (L.) from fishing grounds on the west coast of Scotland has been found to harbour infection by a species of parasitic dinoflagellate. Chromosome morphology and ultrastructural features suggest that the parasite is a member of the botanical order Syndiniales, possibly related to Hematodinium perezi Chatton & Poisson 1931. Cells invading the haemal spaces, however, show no signs of flagella. Mode of transmission is not yet known, and a flagellate spore stage has not been identified. Infection appears to be fatal to its host, the main cause of death possibly being disruption of gas transport and tissue anoxia caused by the proliferation of large numbers of dinoflagellate cells in the haemolymph. Severe infection has an adverse effect on meat quality that has provoked comment from fisherman and processors. Affected lobsters have been found at all west coast sites surveyed, with peak infection rates reaching 70 % of trawled samples. Infection occurrence shows marked seasonality coincident with the annual moult period of N. norvegicus. An increased prevalence of infection has been observed recently in some areas.