Bucephalid Trematode Disease of Mussels


Category 2 (In Canada and of Regional Concern)

Common, generally accepted names of the organism or disease agent

Bucephalid infection of mussels.

Scientific name or taxonomic affiliation

Prosorhynchus squamatus (=Bucephalus mytili) and Rudophinus (=Prosorhynchus) crucibulum (both in the family Bucephalidae).

Geographic distribution

Northwestern Europe, Britain and three focal location in Atlantic Canada. However trematodes identified as Bucephalus sp. have been reported on the west coast of North America by scientists investigating various contaminants (Kim et al. 1998 and Moles and Hale 2003). Specifically, Kim et al. (1998) reported that Bucephalus sp. infections were equally common in M. edulis species complex and M. californianus on the west coast of the United States but the intensities of infection were significantly lower than in M. edulis on the east coast (Massachusetts to New Jersey). And, Moles and Hale (2003) found that M. trossulus exposed to untreated sewage had a significantly higher prevalence of encysted trematodes (identified as metacercariae of Bucephalus sp.) than mussels from three other beaches (including the secondary wastewater site) in Alaska. Also, Powell et al. (1999) reported Bucephalus-like trematodes in petroleum seep mussels (referred to as Bathymodiolus sp. or Seep Mytilid Ia) from the Gulf of Mexico and indicated that the intensities of infection were extremely high in comparison to shallow-water mytilids and may exert a significant influence on seep mussel population dynamics.

Host species

Sporocysts and cercariae in Mytilus edulis, Mytilus galloprovincialis and possibly other bivalve species.

Impact on the host

Infected mussels are invariably castrated; also causes weakness and gaping which can reduce product value during shipping and marketing.

Diagnostic techniques

Gross Observations: Mantles showed abnormal colouration (patchy yellow-white) in heavily infected individuals. However, early/light infections could not be detected by gross observation.

Histology: Various life stages in the vascular system of mussel sections.

Methods of control

No known methods of prevention or control. In Atlantic Canada, four species of fish (Gadus morhua, Hippoglossoides platessoides, Melanogrammus aeglefinus and Myoxocephalus scorpius) have been recorded as definitive hosts (host in which the adult stage of the parasite occurs) of P. squamatus. Metacercarial host(s) has/have yet to be identified.


Bower, S.M. 1992. Diseases and parasites of mussels. In: Gosling, E. (ed), The Mussel Mytilus: Ecology, Physiology, Genetics and Culture. Elsevier, Amsterdam, pp. 543-563.

Bower, S.M. and A.J. Figueras. 1989. Infectious diseases of mussels, especially pertaining to mussel transplantation. World Aquaculture 20: 89-93.

Coustau, C., Combes, C., Maillard, C., Renaud, F. and B. Delay. 1990. Prosorhynchus squamatus (Trematoda) parasitosis in the Mytilus edulis­Mytilus galloprovincialis complex: specificity and host­parasite relationships. In: F.O. Perkins and T.C. Cheng (eds.) Pathology in Marine Science. Academic Press Inc., New York, p. 291­298.

Coustau, C., I. Robbins, B. Delay, F. Renaud and M. Mathieu. 1993. The parasitic castration of the mussel Mytilus edulis by the trematode parasite Prosorhynchus squamatus: specificity and partial characterization of endogenous and parasite-induced anti-mitotic activities. Comparative Biochemistry and Physiology 104A: 229-233.

Kim, Y., E.N. Powell, T.L. Wade, B.J. Presley and J. Sericano. 1998. Parasites of sentinel bivalves in the NOAA Status and Trends Program: distribution and relationship to contaminant body burden. Marine Pollution Bulletin 37: 45-55.

Lauckner, G. 1983. Diseases of Mollusca: Bivalvia. In: O. Kinne (ed.) Diseases of Marine Animals. Volume II: Introduction, Bivalvia to Scaphopoda. Biologische Anstalt Helgoland, Hamburg, p. 632-673.

McGladdery, S.E., M.F. Stephenson and F. McArthur. 1999. Prosorhynchus squamatus (Digenea: Platyhelminthes) infection of blue mussels, Mytilus edulis, in Atlantic Canada. Journal of Shellfish Research 18: 297. (Abstract).

Moles, A. and N. Hale. 2003. Use of physiological responses in Mytilus trossulus as integrative bioindicators of sewage pollution. Marine Pollution Bulletin 46: 954–958.

Powell, E.N., R.D. Barber, M.C. Kennicutt II and S.E. Ford. 1999. Influence of parasitism in controlling the health, reproduction and PAH body burden of petrolium seep mussels. Deep Sea Research Part I 46: 2053-2078.

Teia dos Santos, A.M. and J. Coimbra. 1995. Growth and production of raft-cultured Mytilus edulis L., in Ria de Aveiro: gonad symbiotic infestations. Aquaculture 132: 195-211.

Citation Information

Bower, S.M., McGladdery, S.E. (2009): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Bucephalid Trematode Diseases of Mussels.

Date last revised: June 2009
Comments to Susan Bower

Date modified: