Effects of infection by the protistan parasite Marteilia relringens on the reproduction of cultured mussels Mytilus galloprovincialis in Galicia (NW Spain)

Abstract

Infection by the protistan Marteilia refringens affects the digestive glands of cultured mussels in Galicia, Spain. Effects of the infection on the reproduction of the mussel were studied at 3 sites. Gonad cycle of mussels involved gametogenesis utilizing stored reserves and leading to spring spawning (conservative strategy). This was followed by various sequences of gonad restoration and spawning utilizing the energy from concurrent feeding directly (opportunistic strategy). M. refringens significantly inhibited gonad development in the periods of opportunistic reproductive strategy, proportionally to infection intensity. However, the inhib~tory effect was not significant in the period of conservatlve strategy, probably because mussels had developed storage tissue before the infection progressed. Development of storage tissue was estimated by the abundance of adipogranular (ADG) cells in the mantle. Infection by M. refringens was clearly associated with inhibition of ADG cell development. The heavier the infection, the lower the abundance of ADG cells. Differences in abundance of ADG cells among categories of mussels with different infection intensity were significant at every site. No significant difference in susceptibility to progression of infection was detected between males and females and a similar mortality rate between sexes can be assumed. Evidence suggests that stress following spawning could enhance the progression of the infection.

Prevalence and infection intensity of the ovarian parasite Marteilioides chungmuensis during an annual reproductive cycle of the oyster Crassostrea gigas

“…Protozoan parasites in the phylum Paramyxea have been extensively studied in areas in which oysters and mussels are commercially raised (Becker & Pauley 1968, Wolf 1977, Figueras & Montes 1988, Villalba et al 1993, Fuentes et al 1995, Renault et al 1995, Camacho et al 1997, Berthe et al 2000, Hine & Thorne 2000. The presence of the ovarian parasite Marteilioides chungmuensis (Comps et al 1986) has been reported from oyster culture grounds in Korea (Chun 1970(Chun , 1972(Chun , 1979 and in Japan (Imai et al 1968, Matsusato & Masumura 1981.…”

Marteiliosis in molluscs: A review

“…Furthermore, the parasite may interfere directly with host feeding and absorption simply by its physical presence. Development of adipo-granular storage cells in the mantle of Mytilus galloprovincialis was shown to be inhibited in the presence of M. refringens (Villalba et al 1993b). Apparently, M. refringens also interferes with glycogen storage in Ostrea edulis (see Robert et al 1991).…”

“…Gametogenesis and gonadal development are reduced or delayed in infected oysters, O. edulis ) and mussels, M. galloprovincialis (Figueras et al 1991;Villalba et al 1993b). Heavily infected individuals may reach the point of being unable to start a new gametogenic cycle in the following year.…”

“…Heavily infected individuals may reach the point of being unable to start a new gametogenic cycle in the following year. On the other hand, spawning stress itself may enhance the progression of the disease (Villalba et al 1993b).…”

Parasites, pathological conditions and resistance to Marteilia cochillia in lagoon cockle Cerastoderma glaucum from Galicia (NW Spain)

“…Three species of the genus Marteilia, viz. M. refringens (Villalba et al 1993), M. cochillia (Villalba et al 2014) and M. octospora (Ruiz et al 2016), occur in Galicia, including the Ría de Arousa where the 2 lagoon cockles infected with a Marteilia-like parasite were found. Even if M. cochillia was the species infecting those 2 lagoon cockles, C. glaucum should be considered resistant to M. cochillia since no case of advanced infection with fully developed parasites was detected (only 2 out of 520 individuals were lightly infected with immature parasite stages).…”