Relationships of Some Species of Digenea with the Marine Prosobranch Littorina littorea (L.) I. The Occurrence of Larval Digenea in L, littorea on the North Yorkshire Coast

Abstract

1. 8515 specimens of the common periwinkle, Littorina littorea (L.), from four localities on the North Yorkshire coast were examined for larval Digenea during 1966 and 1907. Four species were found, namely Cryptocotyle lingua (Creplin, 1825), Himasthla leptosoma (Creplin, 1829), Cercaria lebouri Stunkard, 1932 and Cercaria A, the incidence of infection with which correlated with the presence of sea bird and wader final hosts.2. 5878 of all L. littorea examined were from one locality of relatively high incidence of infection where there were seasonal changes in incidence, being greatest during the autumn and early winter and least during the summer. The incidence of infection was higher in larger than in smaller periwinkles except in infections with an unidentified species, named Cercaria A, where the incidence declined sharply in L. littorea above 25 mm shell length. The ecology of the infections is discussed.

Occurrence of the digenean Cryptocotyle lingua in farmed Arctic charr Salvelinus alpinus and periwinkles Littorina littorea sampled close to charr farms in northern Norway

“…There were variations in incidence of infection among both the farm and control sites, and factors such as inter-tidal environmental conditions and differences In resistance among periwinkle strains may influence the abundance of C. lingua in snail hosts (Robson & Williams 1970). There is, however, no reason to believe that such factors would have led to the higher levels of infection recorded in periwinkle population~ collected adjacent to the fish farms in the current study.…”

“…Several authors have concluded that the presence and behaviour of piscivorous birds have the most decisive impact upon the incidence of infection of Cryptocotyle lingua in periwinkle populations (Hoff 1941, Sindermann & Farrin 1962, Robson & Williams 1970, Hughes & Answer 1982, Irwin 1983, Matthews et al 1985, Lauckner 1987. Although not quantified, quite large numbers of birds were observed in the vicinity of the farms during the current investigation.…”

“…1 the charr cages were situated in brackish water of low temperature (8 "C). Production of C. lingua cercariae ceases when the temperature drops below 8 to 10 'C (Sindermann & Farrin 1962, Robson & Williams 1970. Further, Moller (1978) demonstrated that both low temperatures and low salinities have a negative effect upon the development, infectivity and sunrival of the free-living stages (eggs and cercaria) of C. lingua.…”

“…Seawater temperature was measured at each farm site (Table 1). Since prevalence of infection with Cryptocotyle lingua m periwinkles is known to increase with increasing snail size (James 1968a, Robson & Williams 1970, Lauckner 1984, 1987, Matthews et al 1985, the largest specimens were collected at each site. Immediately after collection, shell height of the periwinkles was measured to the nearest 0.1 mm using a slide caliper.…”

Trematode Infections inLittorina littoreaon the New Hampshire Coast

“…Although seasonal variation in the prevalence of parasitic infections in intertidal snails is common (L. littorea: Hughes and Answer 1982, Lauckner 1987, Pohley 1976, Robson and Williams 1971, Sindermann and Farrin 1962Hydrobia spp: Field andIrwin 1999, Kube et al 2002), we sampled during summer because a higher prevalence of infection occurs during summer months compared to winter months. Poulin and Mouritson (2003) attribute low prevalence of infection during winter months to ambient water temperatures.…”