REVIEW Review: Bucephalus minimus, a deleterious trematode parasite of cockles Cerastoderma spp. L. Magalhães & R. Freitas & X. de Montaudouin Received: 28 January 2015 /Accepted: 4 February 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract Trematodes are the most prevalent and abundant macroparasites in coastal waters. They display a complex life cycle with alternation of free-living and parasitic stages gen- erally involving three host species. The most deleterious stage is in the first intermediate host (a mollusc) where the parasite penetrates as miracidium larvae and asexually multiplicates in sporocysts/rediae to provide cercariae larvae. However, due to basic low prevalence in ecosystems, this system remains dif- ficult to study. Taking the example of the cockle (Cerastoderma edule), an exploited bivalve along North- Eastern Atlantic coasts, and Bucephalus minimus, its most prevalent parasite as first intermediate host, we summarised the 51 most relevant papers (1887–2015). Besides, a 16-year monthly monitoring was performed at Banc d’ Arguin (Atlantic coast of France), and allowed to obtain a sufficient number of infected cockles (276 out of 5,420 individuals) in order to provide new information concerning this parasite/host system. Sporocysts (diameter 80–500 μm) and developing cercariae (length 300–500 μm) are not visible before cockle reaches 16-mm shell length and then prevalence increases with host size. Seasonality of infection was not observed but variation of prevalence was significant among years and neg- atively correlated to the temperature of the former year, which could correspond to the period of infection by miracidium. Seven other species of trematode were identified in cockles as second intermediate host. For six of them, metacercariae abundance per individual was 2 to 12 folds higher in B. minimus-infected cockles, exacerbating the potential nega- tive impact on host. From the parasite point of view, metacercariae can be considered as hitchhikers, taking advan- tage of the abnormal migration of B. minimus-infected cockles to the sediment surface where they become more vulnerable to predators that are also the final hosts of many of these parasites. Keywords Bivalve . Cerastodermaedule . Long-termseries . Parasite . Trematode . Bucephalus minimus Introduction Parasites can seriously interfere with host population perfor- mance (Curtis 1995; de Montaudouin et al. 2014; Jonsson and André 1992), although their precise contribution often re- mains neglected. Trematodes are the most abundant and com- mon macroparasites in coastal waters (Lauckner 1983; Schmidt and Roberts 2000). They display a complex life cycle with alternation of sexual and asexual generations and of par- asitic and free-living stages. Thus, the parasite experiences totally different habitats in which the various stages must sur- vive, with physiological adjustments that must often be made extremely rapidly (Schmidt and Roberts 2000). There are also contrasted effects on host fitness according to parasite stage in the life cycle. The typical life cycle of a trematode (Esch et al. 2002) includes the following (Fig. 1): (a) a ciliated and swimming larva, the miracidium (free-living stage) which penetrates the first intermediate host (a mollusc); (b) the larva metamorpho- ses into a rather simple sac-like form, the sporocyst (parasitic stage). The sporocyst evolves in a more mature form of L. Magalhães (*) : R. Freitas Departamento de Biologia & CESAM, Universidade de Aveiro, 3810-193 Aveiro, Portugal e-mail: luisa.magalhaes@ua.pt L. Magalhães : X. de Montaudouin Université de Bordeaux, EPOC, UMR 5805 CNRS, 2, rue du Pr Jolyet, 33120 Arcachon, France Parasitol Res DOI 10.1007/s00436-015-4374-6