Deng, B.L. (2018). Patterns of parasitism in native and invasive freshwater mussels -- testing the enemy release hypothesis. Master's Thesis, University of Jyväskylä, Jyväskylä, Finland. 36 pp.

508806

Deng, B.L.

2018

36 pp.

Publication

https://urn.fi/URN:NBN:fi:jyu-201808153836

Available for editors  

Freshwater mussels are regarded as ‘key stone’ species, since their filtration and other activities provide important services in aquatic ecosystems. However, freshwater mussels are facing more and more threats worldwide, one of which is the invasion of alien mussel species – one of the main causes of population declines and extinctions of native freshwater mussels. The aim of this study was to test the Enemy Release Hypothesis – which argues that invaders’ success results from reduced natural enemy attack, for example, parasites, by comparing the parasitism pattern between native and invasive freshwater mussels. Native and invasive mussels were collected from four lakes (Lake Võrtsjärv in Estonia, Lake Nowy Lipsk in Poland, Lake Mergozzo and Lake Varese in Italy) with eight reference lakes from Finland where no invasive mussels occur. Alien species samples included the Asian clam Corbicula fluminea from lakes Nowy Lipsk, Mergozzo and Varese, Chinese pond mussel Sinanodonta woodiana from Lake Nowy Lipsk, and zebra mussel Dreissena polymorpha from Lake Võrtsjärv. Native species in this study were the duck mussel Anodonta anatina (Võrtsjärv, Nowy Lipsk), swan mussel Anodonta cygnea (Nowy Lipsk, Mergozzo,Varese), painter’s mussel Unio pictorum (Võrtsjärv, Nowy Lipsk), swollen river mussel Unio tumidus (Nowy Lipsk) and Unio elongatulus (Mergozzo, Varese). Parasite species found included 5 digenean trematodes: Rhipidocotyle fennica, R. campanula, Cercaria duplicata, Phyllodistomum macrocotyle, Aspidogaster conchicola; the oligochaete Chaetogaster limnaei, the chironimid Glyptotendipes sp., the ergasilid copepod Paraergasilus rylovi as well as adult and larval water mites, a total of 11 parasite taxa. Number of parasite taxa, prevalences and intensities of infection varied between lakes and mussel species, but the parasite taxa richness and the sum of prevalences of infection, both were, on average, statistically significantly higher (4 and 6 times higher, respectively) in the native mussels than among the invasive mussels. The average (± s.e.) mean number of parasite taxa in native and invasive mussels were 4.1 ± 0.4 and 0.9 ± 0.5, while the average (± s.e.) mean sum of prevalences were 139.1 ± 12.9 and 22.9 ± 21 %, respectively. For example, the invasive species C. fluminea (three lakes, n = 117) was completely uninfected. Thus, the results indicate that lower parasite load in invasive mussel species compared to the native ones can benefit invasive mussels and therefore contribute to their success. In addition, the reference data from Finland showed high diversity of parasites infection rates (mussel species found were A. anatina, A. cygnea, Pseudanodonta complanata, U. tumidus and U. pictorum) among different species. To conclude, these results support the Enemy Release Hypothesis as a relevant explanation for the success of biological invasions.

RIS (EndNote, Reference Manager, ProCite, RefWorks)
BibTex (BibDesk, LaTeX)

[Back to search]