Relationship between prevalence of trematode parasite Diplostomum sp. and population density of its snail host Lymnaea stagnalis in lakes and ponds in Finland

Abstract

Diplostomum sp. is a trematode parasite that infects aquatic snails, e.g. Lymnaea stagnalis (Gastropoda: Lymnaeidae), fish, and fish-eating birds. Ponds and lakes (n = 28) located in Finland between latitudes 61°45 0 N and 65°30 0 N were sampled for L. stagnalis, the first intermediate host for Diplostomum sp. L. stagnalis were found in 22 sites out of 28, and Diplostomum sp. in 10 of the 22 snail populations. Among the L. stagnalis populations that were infected by Diplostomum sp., the mean prevalence was 12.8%. Diplostomum sp. occurred in only one out of the seven L. stagnalis populations in four large lakes, but in 9 out of the 16 L. stagnalis populations in small lakes. In the pooled data, a positive correlation (r s = 0.427; P = 0.047; n = 22) between L. stagnalis density and Diplostomum sp. prevalence was found. The results suggest that Diplostomum sp. is fairly common in L. stagnalis populations in small lakes but rare in large lakes. Furthermore, although trematode parasites, in general, should have a negative effect on snail population density, the study indicates that the relationship between host density and parasite prevalence may greatly differ for individual trematode species, such as Diplostomum sp.

Activation of the immune defence of the freshwater snailLymnaea stagnalisby different immune elicitors

“…The lack of responses in the group of snails injected with trematode-infected gonad tissue is unexpected because a strong immune response could be assumed against trematode parasites as they are highly virulent (e.g. Karvonen et al, 2004) and also common in natural snail populations (Väyrynen et al, 2000;Voutilainen et al, 2009). However, it is possible that responses are simply not seen in the parameters measured in this experiment if some other defence mechanisms are used against them.…”

The invasive Chinese pond mussel Sinanodonta woodiana (Lea, 1834) as a host for native symbionts in European waters

“…This is possible due to both the biological characteristics of the species (large body size and biomass) and its ecological features (tolerance to water pollution and oxygen deficits) (Dudgeon and Morton, 1983;Du et al, 2011). Some authors emphasize that host density is a key parameter determining the prevalence of hosts (Arneberg et al, 1998;Voutilainen et al, 2009). In our study, higher density of S. woodiana was noted in heated lakes (Kraszewski and Zdanowski, 2001;Spyra et al, 2012), but higher prevalence of mussels was observed in fish ponds.…”

Relationships between nutrient enrichment, pleurocerid snail density and trematode infection rate in streams

“…Positive relationships between trematode infections in snails and secondary intermediate hosts (e.g. amphibians) and the density and species richness of snails have been documented in mesocosm experiments and field studies of standing waters (Johnson et al, 2007;Rohr et al, 2008;Voutilainen et al, 2009). However, other studies have shown that the abundance of vertebrate definitive hosts (e.g.…”