The dreissenid zebra (ZM) and quagga mussel (QM), which belong to the world’s most successful invaders, endanger native unionid (U) mussels through their intensive biofouling. The two dreissenid species are closely related but different in many aspects. Our goal was to explore the mechanisms underlying interspecific differences in biofouling between them. We investigated size, density, and substratum specificity of dreissenids on different living (U shells) and non-living (stones) substrata, using long-term field datasets of Lake Balaton, Hungary, from the beginning of QM invasion. We carried out lab experiment focusing on the re-colonization and post-settlement movement behavior of dreissenids regarding their substrate preferences. ZM occupies hard objects, especially stones, more often than QM. In contrast, QM more often selects U shells, but also detaches from buried substratum more often than ZM. In the field, ZM was more frequent, its density was higher and its population was more stable than that of QM. Infestation intensity of U in the field by ZM was overall higher than by QM despite the decline of the former. The observed field differences are not considered as recruitment preferences, it rather can be explained by the detachment of QM from substrate. The long term field survey also confirmed that U population may provide shelter for ZM against QM invasion. The pressure on native host species can be lower in those habitats where only QM appears and can be expected to decrease in habitats where the previously introduced ZM has been displaced by the new invader.

Primary Presenter: Csilla Balogh, Balaton Limnological Research Institute, Eötvös Lóránd Research Network (balogh.csilla@blki.hu)

Authors:

Csilla Balogh, Balaton Limnological Research Institute, Eötvös Lóránd Research Network  (balogh.csilla@blki.hu)

Lukasz Jermacz, Nicolaus Copernicus University, Faculty of Biological and Veterinary Sciences, Department of Invertebrate Zoology and Parasitology, Torun, Poland  (jermacz@umk.pl)

Zoltan Serfozo, Balaton Limnological Research Institute, Eötvös Lóránd Research Network  (serfozo.zoltan@blki.hu)

Jaroslaw Kobak, Nicolaus Copernicus University, Faculty of Biological and Veterinary Sciences, Department of Invertebrate Zoology and Parasitology, Torun, Poland  (jkob73@umk.pl)