Parasitic mite and trematode abundance are associated with reduced reproductive output and physiological condition of freshwater mussels

Abstract

Although historically understudied, parasites may play an important role in freshwater invertebrate population ecology and evolution. We quantified abundance of parasitic mites and trematodes in the freshwater mussel Pyganodon grandis, in a southeastern Alabama stream (USA), to assess parasite impact on adult mussel physiological condition and reproductive output. We used stepwise multiple regression analyses to assess the effects of mussel size and parasites on reproduction and condition. Multiple regression analysis found no multivariate models that predicted reproductive output or physiological condition. However, univariate models revealed that increased parasite densities predict reduced mussel reproductive output and physiological condition. These findings suggest that parasites may have important negative consequences for freshwater mussels. We hypothesize that elevated parasite loads may reduce mussel fitness in impounded or nutrient-enriched streams with high densities of intermediate hosts (chironomid midges).

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

“…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.…”

“…The presence of the water mites in fish ponds, where the high number of chironomids was noted, is not surprising, as unionicolids use the chironomid larvae as hosts in the life cycle (Baker, 1991). The adult forms of unionicolid water mites are attached to the gills of mussels and cause displacement, rupture, and erosion of the gill epithelium (Baker, 1976;Edwards and Vidrine, 2006;Fisher et al, 2000;Gangloff et al, 2008).…”

Behaviour and physiology are linked in the responses of freshwater mussels to drought

“…Opintlocco Creek is a low-gradient stream (<1%) situated in the Gulf Coastal Plain, and the dominant substratum is sand and silt (<2 mm; Gangloff, Lenertz & Feminella, 2008). Opintlocco Creek is a low-gradient stream (<1%) situated in the Gulf Coastal Plain, and the dominant substratum is sand and silt (<2 mm; Gangloff, Lenertz & Feminella, 2008).…”

“…Our study was in the headwaters of Opintlocco Creek, located in the Tallapoosa catchment of east central Alabama (32°22¢42¢¢N, 85°26¢54¢¢W). Opintlocco Creek is a low-gradient stream (<1%) situated in the Gulf Coastal Plain, and the dominant substratum is sand and silt (<2 mm; Gangloff, Lenertz & Feminella, 2008). The headwaters have intermittent flow in drought years.…”

Factors affecting trematode infection rates in freshwater mussels

“…Fragmentary evidence suggests that digenean trematodes may affect physiology (Jokela et al, 1993), growth (Taskinen, 1998, and reproductive ability (Taskinen & Valtonen, 1995) of their bivalve hosts. Similarly, aspidogastrean trematodes were observed to negatively impact physiology and growth of their mussel hosts (Gangloff et al, 2008). The selective pressure of digenean trematodes has only occasionally been considered in research on bivalve life history (Haukioja & Hakala, 1978;Jokela & Mutikainen, 1995, but see Jokela et al, 2005.…”