“…There has been little agreement, however, as to the nature of the seasonal cycle or its cause (Brousseau and Baglivo, 1991). Seasonal trends in the prevalence of DN have been reported in oysters O. edulis (Balouet et al, 1986;da Silva et al, 2011) and O. lurida (Farley and Sparks, 1970;Farley, 1976), in mussels M. trossulus (Farley and Sparks, 1970;Farley, 1976;Mix, 1983;Cosson-Mannevy et al, 1984;Rasmussen, 1986), in clams M. arenaria (Cooper et al, 1982b;Farley et al, 1986;Brousseau, 1987a;Barber, 1990;Leavitt et al, 1990;Farley et al, 1991;Böttger et al, 2013) and M. balthica (Christensen et al, 1974;Wolowicz et al, 2005), and in cockles C. edule (Twomey and Mulcahy, 1988b;Iglesias, 2006;Le Grand et al, 2010). Fig.…”