Factors affecting trematode infection rates in freshwater mussels

Abstract

Mussels are intermediate hosts of digenean trematodes, but determinants of these infections remain unknown. To address this problem, we collected duck mussels Anodonta anatina in eighteen lakes from northeastern Poland and examined how mussel age, sex, and the encrustation with zebra mussels Dreissena polymorpha and environmental conditions in lakes influenced infection rates. We also assessed parasitic preferences to host gonads and hepatopancreas and the impact of parasites on female fertility. Mussels were infected with Rhipidocotyle campanula and Phyllodistomum sp. Infection rates were higher in older and female mussels but were unrelated to the biomass of encrusting D. polymorpha and the trophy, thermal conditions, and Ca 2? availability. Parasites occupied gonads more often than hepatopancreas. Infected females were less likely to carry glochidia and incubated fewer glochidia. We suggest that the risk of infection by digenean trematodes increases with the amount of water processed by filter-feeding hosts and/or that parasites actively seek hosts which can provide them with abundant resources. This mechanism explains why parasites more often occupied older and female mussels and targeted their gonads. Future research on trematodemussel interactions should integrate knowledge on different elements of the complex trematode life cycles, including effects of higher-order hosts such as fish.

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

“…The presence of R. campanula in the gonads is the first recorded case of occurrence of bucephalid larval stages in S. woodiana in Poland and probably in Europe. The prevalence of Chinese pond mussels inhabited by R. campanula was comparable with the results noted by Baturo (1977) and Müller et al (2015) in native bivalve species (Unio pictorum and Anodonta anatina, respectively). In our research, R. campanula was found in S. woodiana only in thermally polluted lakes.…”

“…In native bivalve species, e.g. A. anatina, the presence of bucephalid trematodes decreases the production of glochidia (Taskinien and Valtonen 1995), causes partial or complete castration (Jokela et al, 2005;Gangloff et al, 2008;Müller et al, 2015), increases mortality (Taskinen et al, 1997) and causes changes in shell shape (Zieritz and Aldridge, 2011). The ecological consequences of the infestation of Chinese pond mussels by R. campanula remain unknown and further studies should address the question of whether this parasite significantly burdens its exotic hosts and thus may limit their spread.…”

Continuous reproduction of Sinanodonta woodiana (Lea, 1824) females: an invasive mussel species in a female-biased population

“…The structure of ovaries in S. woodiana was similar to that found in other Unionoidea mussels (Yokley, 1972;Grande et al, 2001;Chatchavalvanich et al, 2006;Sehriban & Sereflisan, 2006;Hinzmann et al, 2013;Müller et al, 2015). Reproductive follicles contained nurse cells and reproductive cells in different developmental phases.…”

Genome survey of the freshwater mussel Venustaconcha ellipsiformis (Bivalvia: Unionida) using a hybrid de novo assembly approach

“…Mussels are filter feeders and tissues as gills can potentially harbor microbial fauna. In addition, freshwater mussels are prone to infection by trematodes (Müller et al 2015, Capt et al 2018. As suggested by Takeuchi et al (2012), we first checked for the presence of double peaks in the distribution of the GC content of the raw reads, which would indicate contamination in the genome.…”