Component Community of Larval Trematodes in the Mudsnail Hydrobia Ventrosa: Temporal Variations in Prevalence in Relation to Host Life History

Abstract

Temporal variations in the prevalence of larval trematodes in the short-lived prosobranch mudsnail Hydrobia ventrosa (Montagu) were investigated in relation to host life history and season for 4 successive years in temperate windflats of the southern Baltic Sea. The component community of trematode larvae in H. ventrosa comprises at least 10 species; families (and species) represented include Notocotylidae (1), Echinostomatidae (1 or 2), Heterophyidae (2), Monorchidae (1), Microphallidae (3 or 4), Psilostomatidae (1), and Hemiuridae (1). The notocotylid Paramonostomum alveatum was the most prevalent species, followed by the microphallids Maritrema subdolum and Microphallus sp. Trematode prevalence in H. ventrosa fluctuated seasonally. Prevalence usually peaked in summer between July and September-October and decreased in late winter-early spring. This seasonal change is chiefly explained by the life history patterns of the semelparous snail host. Hydrobia ventrosa has a maximum life span of about 2 yr and reproduces between June and November of its second calendar year. The first trematode infections appeared annually in May when the most abundant cohort of H. ventrosa, the second-calendar-year snails, mature. The prevalence continued to increase until August-September, throughout the reproductive period of the second-calendar-year snails, Prevalence decreased during winter, when most of the second-calendar-year snails died after reproduction. On the basis of longterm laboratory experiments, it has been shown that the late autumn-winter mortality was not the result of trematode infections. Seasonal patterns of prevalence were similar among the trematode species except for the monorchid Asymphylodora demeli, the only one using fish definitive hosts. Species-specific differences in the seasonal occurrence of prepatent infections and the predominance of certain larval stages in winter are interpreted as different strategies of the trematode species to survive the harsh winter conditions, or to survive the death of the first intermediate host in autumn-winter, or both.

Trematode Infections inLittorina littoreaon the New Hampshire Coast

“…Generally, larger (typically assumed to be older) snails are more likely to be infected with parasites than smaller snails due to an increased opportunity to become infected over time (Hughes and Answer 1982, James 1968, Kube et al 2002, Matthews et al 1985, Pohley 1976. We found few small snails (<14 mm) to be infected.…”

Seasonal dynamics in an intertidal mudflat: the case of a complex trematode life cycle

“…Other studies have reported different seasonal patterns, with lows in prevalence during winter and spring and peaks in summer (e.g. Hughes & Answer 1982, Kube et al 2002b or similar patterns of maximum levels in winter and spring (e.g. Al-Kandari et al 2000).…”

“…Seasonal changes in trematode prevalence in snail hosts have been attributed to the life history of the snail host, e.g. age structure, recruitment or mortality, seasonal changes in ambient temperatures or the biology of the final hosts, including abundance or behaviour (Kube et al 2002b and references therein). Also, seasonal infection patterns in snail hosts have been linked to infection-status-specific winter migration toward low shore and subtidal areas (Sindermann 1960, Sindermann & Farrin 1962, a possibility that remains unexplored in the system studied here but that may account for some of the patterns observed.…”

“…Smith 2001, Kube et al 2002a, Latham & Poulin 2003, Hechinger & Lafferty 2005, Byers et al 2008) but also temporally (e.g. Hughes & Answer 1982, Lauck ner 1987, Meißner & Bick 1997, Al-Kandari et al 2000, Kube et al 2002b, Jen sen et al 2004, Al-Kandari et al 2007). Many aspects of the transmission of trematodes are influenced by temperature, and thus, seasonal changes in temperature are bound to affect transmission dynamics (e.g.…”

Temporal variation in prevalence and cercarial development of Echinostephilla patellae (Digenea, Philophthalmidae) in the intertidal gastropod Patella vulgata

“…Whilst in short-lived (< 2 years) gastropods the observed dynamics are largely attributable to life history characteristics of the host (Esch and Fernandez 1994, Field and Irwin 1999, Kube et al 2002, temporal patterns in long-lived hosts are often inconsistent and causes of variation in the frequency of infection are less clear (Sindermann and Farrin 1962, Esch and Fernandez 1994, Ngo and Choi 2004. Similar to the findings of previous investigations (Robson and Williams 1970, Lang and Dennis 1976, Sannia and James 1978, Hughes and Answer 1982, which revealed an increase in infection rates during the warmer months of the year, our study showed prevalence of Echinostephilla patellae infections in Patella vulgata to peak in September, suggesting recent miracidial invasions.…”