Faculty of Biology
PhD thesis: Influence of Pomphorhynchus sp. and Anguillicola crassus on physiological parameters of the European and Japanese eel
My doctoral thesis is dealing with the stress and immune response of European and Japanese eels on infestations with two invasive parasites, Pomphorhynchus sp. and Anguillicola crassus. The Asian swim bladder nematode A. crassus was introduced to Europe in the early 1980s with infested Japanese eels and is spreading among the population of the European eel since then.
The acanthocephalan Pomphorhynchus sp. is native in different fish species from the Ponto-Caspian-Region and was introduced to the river Rhine after the inauguration of the Main-Danube-Canal. The invasive round goby (N. melanostomus) likewise from the Ponto-Caspian-Region is a suitable paratenic host for Pomphorhynchus sp. and was first described in the river Rhine in 2008.
In contrast to the European eel, there is no stress response of the Japanese eel to infestations with its naïve parasite A. crassus, due to coevolutionary adaptations. Furthermore, Pomphorhynchus sp. is unknown to both eel species, what makes these eel-parasite-systems interesting for comparative studies. To display the stress and immune response I’m measuring cortisol and antibody responses of the eels to infestations pf these parasites.
Before the introduction of A. crassus to Europe, the closely related species A. novaezelandiae was present in Italy, but rapidly displaced by the more successful invader A. crassus. Fertile offspring by hybridization of this two species, is one possible hypothesis for the invasion success. This question is part of my thesis, as well.