Parasites in sympatric populations of native and invasive freshwater bivalves

Abstract

An increasing threat to local, native freshwater mussels (Unionida)-an ecologically important but globally alarmingly declining groupis the invasion by exotic bivalves. The Enemy Release Hypothesis predicts that introduced species should benefit from enemy-mediated competition because they are less likely to be harmed by natural enemies, such as parasites, than their native competitors. We investigated within-site differences in parasitism between sympatric native (tot. five spp.) and invasive (tot. three spp.) bivalves in eight northern European waterbodies, which harboured totally 15 parasite taxa. In paired comparisons using within-site averages, the mean number of parasite species in the native bivalves was 2.3 times higher, and the sum of parasite prevalences 2.4 times higher, than in the invasive bivalves. This may lead to enemy-mediated competitive release of invaders and contribute to the success of invasive freshwater bivalves, in general. However, while the invasive clam Corbicula fluminea was completely free from parasites, parasite parameters of the other invader, Sinanodonta woodiana, were relatively high, indicating that the role of parasites can be invader-specific and urges further research. Understanding the factors affecting success of freshwater bivalve invasions, such as parasitism, can aid invasion

The Chinese pond mussel Sinanodonta woodiana demographically outperforms European native mussels

“…The ability of S. woodiana to outcompete native mussels has been predicted based on its exceptional body-size, with a shell length reaching over 25 cm and total wet body mass over 1.5 kg 7 , 24 , high filtration rates 25 , ability to induce cross-resistance in the host fish 26 , and a possible role in transmitting parasites and diseases 27 , 28 . Despite these predictions, the impacts of S. woodiana on the population dynamics of native mussels, as far as we know, have not been studied before.…”

The first record of the swordtailXiphophorus helleriiHeckel, 1848 (Poeciliidae, Actinopterygii) established in the wild from Morocco

“…Besides to the high fecundity rate and trophic opportunism, the swordtail has proved its invasiveness also because of its tolerance for wide environmental factors and the ability of colonizing anthropogenic modified ecosystems (Arthington, Hamlet, & Bluhdorn, 1990; Bomford & Glover, 2004). Furthermore, invasive species can acquire parasites in the invaded area either by bringing them along themselves or by infection by parasites of the native species (Taskinen et al., 2020). In addition to several fungal and bacterial diseases, many different parasites have been found to be hosted by the swordtail, probably because it is a very popular fish and has been thoroughly studied (Froese & Pauly, 2019; Garcia, Fujimoto, Martins, & Moraes, 2009; Thilakaratne, Rajapaksha, Hewakopara, Rajapakse, & Faizal, 2003).…”

First record of metacercariae trematodes Opisthioglyphe ranae (Digenea: Telorchiidae) and Echinostoma bolschewense (Digenea: Echinostomatidae) in Dreissena polymorpha (Bivalvia: Dreissenidae) from the Don and Volga river basins, Russia

“…The tissues were dissected and inspected, piece by piece, by pressing them between two large glass plates followed by examination under a light microscope AxioLab.A1 (Carl Zeiss, Germany) (Taskinen et al 2020).…”

“…This is due to the fact that D. polymorpha populations are able to create extremely numerous populations to an increasing in the likelihood of infecting the final hosts. At the same time, the parasites can have a significant impact on their hosts in such ways as population dynamics, life cycle, food webs, physiology, growth, and reproductive ability of their hosts (Kraak & Davids 1991;Molloy et al 1997;Laruelle et al 2002;Müller et al 2015;Taskinen et al 2020). Thus, there is a need to study zebra mussel populations and their role waterbodies as a host of parasites (Mastitsky 2004;Burlakova et al 2006).…”