engleski

Harmful epiendobiosis of Eugymnanthea inquilina (Cnidaria, Hydrozoa) and doubtful parasitism of Urastoma cyprine (Turbellaria, Holocoela) in the Mytillus galloprovincialis (Bivalva)

Marine bivalves act as hosts to many viral, bacterial, protozoan and invertebrate parasites. Among them, Mytilus galloprovincialis Lamarck, 1819, being an economically important species with annual global landings of 86.624 tones (FAO, 2008) represents the most constant resource for scientific research concerning pathogens that could influence aquaculture production. In South Adriatic Sea, where Croatian culturing of M. galoprovincialis is the highest, so far no heavy diseases or mortality outbreaks have been reported. Turbellarians in general are accepted as hermaphroditic free-living Platyhelminthes, although each of their groups includes species that form particular associations with other organisms. These associations are relatively of undefined and unresolved character, mostly just termed commensal, although for some, evidence of obligate parasitism has been found. Parasitic turbellarians affect their bivalve hosts in different ways, usually inhibiting and retarding host gametogenesis, growth and overall condition, or directly inducing tissue damage. Rarely, sudden mortalities of the hosts are observed and most authors agree that their infections result in negligible pathology and economic loss. However in Croatian mussel culturing, an increased prevalence and abundance of the epiendobiont Eugymnanthea inquilina (Cnidaria, Hydrozoa) and turbellarian Urastoma cyprine (Turbellaria, Holocoela) has been observed lately. Faced with such a sudden event, the aim of our research was to asses if turbellarian U. cyprine and cnidarian E. inquilina impose any pathological effect on subcellular, cellular and histological level on overall growth and reproduction of cultured M. galloprovincialis. Our data inferred by TEM indicate that U. cyprinae evokes intense immune reaction that results in encapsulation of the parasite, while necrosis and shedding of mantle epithelial cells occurs at the contact of the cnidarian and bivalve. Cell apoptosis inferred by positive caspase reaction was observed only in case of the turbellarian parasitation.

hydrozoa; turbellaria; Mytillus galoprovincialis

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