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Dissertation: The invasion of alien mussel species threats freshwater mussels (Deng)

Doctoral researcher Binglin Deng examines in her doctoral thesis the ability of alien mussels to resist parasites compered to local freshwater mussels. The results help to understand the complex processes that likely underlie biological invasions and improve our ability to manage natural ecosystems.

Bioinvasion or invasive species have been creating “chaos” in ecosystem of invaded range that possibly lead to the loss of biodiversity and genetical homogeneous. Economically, the summed-up cost of invasive species in Europe was €138.6 billion between year 1960 and 2020 which can be huge burden to the society. 

• The emergent question is: Is there a general rule in bio-invasion, is there a common trait on the invasive species that successfully colonize new environments?, wonders doctoral researcher Binglin Deng from Ģ��ֱ��.

Invasive species had harbored less parasites

Among all the hypotheses explaining the success of invasion, Enemy Release Hypothesis (ERH) is the most popular and well-known one, which posit that invaders are released from natural enemies e.g. predators, parasites or pathogens and therefore, having advantage when competing with local species. 

First in the study, parasite pressure with parameter of parasite taxa richness and sum of prevalences were compared between sympatric population of native and invasive species from same sampling site in Europe (11 waterbodies).

• It is shown in the study that three invasive species on averagely harbored less parasites than native freshwater mussels and in invaded ranges, explains Deng. 

Protecting and enhancing the resilience of ecosystems

Second, the parasite pressure in the invasive bivalves S. woodiana and C. fluminea was compared between populations in the original range (China, 5 waterbodies) and the invaded range (Europe, 11 waterbodies). A reduction of parasite pressure was observed from both species in invaded ranges which means they have experience release from natural enemies and contribute to the success of invasive freshwater bivalves. Parasites are ubiquitous parts of planet that despite they are small in size but have great impact on the host and ecosystem.

• I believe this study provides a new dimension toward invasion of freshwater bivalves and offers a piece to the puzzle of bioinvasion ecology. It may help expand our understanding of the complex processes that likely underlie biological invasions and improve our ability to manage natural ecosystems, says Deng. 

The examination of M.Sc. Binglin Deng "Enemy Release hypothesis: Parasitism in invasive and native freshwater bivalves" is held on 7.6.2024 at 12:00 at S212 Seminaarinmäki. The Opponent is University Lecturer, Docent Satu Ramula (University of Turku) and custos is Professor Jouni Taskinen (Ģ��ֱ��). 

The dissertation can be read on the JYX publication archieve: