Aquatic parasitology

Despite omnipresence, parasites are neglected in ecosystem studies. Parasitism is the most successful mode of life on earth. The number of parasitic organisms exceeds the non-parasitic, their biomass those of large predators.

Parasites link different organisms (their intermediate and final hosts) in the system. Fundamental research on species taxonomy and host-parasite interactions are necessary, especially in species-rich, unexplored tropical waters.

Applied, advanced research is needed concerning the co-evolution of parasites with their fish hosts and their harmful potential. Consumers are affected (keywords: aquaculture, fisheries and food hygiene), especially concerning zoonoses (parasitic diseases transmitted via animals to humans). There is also a need to use fish parasite species as biological indicators, e.g. for fish or ecosystem health status or population studies.

We are working on the general questions of aquatic parasitology. For this purpose, the team - from the student to the post doc or the professor - investigates fish stocks and parasites worldwide.

For Indonesia, a host-parasite list including all known fish and parasite species could be developed. New species are described, new host and area proofs are provided. Insights into the interactions of biodiversity are given.

The same is true for the waters of Hawaii, Vietnam, the Gulf of Oman and the Persian Gulf, in whose parasite communities for the first time detailed insights are given, also by new species descriptions. European freshwater bodies and the Baltic Sea are sampled and recorded for the first time in this form.

Certain species are examined for their suitability for biological indication, e.g. environmental pollution or climate change. For this purpose, the Professorship for Groud- and Soil Research developed - for the first time – a methodology in which parasitic worms are examined for pollutant accumulations. With our "Star-Graph" the biological indication can be visualized and made understandable. Systems can be evaluated with regard to their potential or health status.

Molecular genetic analyzes show phylogeny and co-evolution, e.g. with fish. Malicious parasites are detected and facility management methods are developed. We identify the vectors for zoonoses and inform the public how to avoid them by choosing harmless fish species and correct cooking/preparation.

In addition to standard fish techniques (fish / organ examination, parasite fixation, dyeing, DIC light, electron and confocal microscopy, drawing by means of Camera Lucida, image documentation, surveys for (new) species determination), molecular genetic methods (DNA sequence analysis / alignment, phylogenetic stem trees) are applied. Natural biodiversity and commercial aquaculture from Northern European lakes, the Baltic Sea, the Indo-Pacific (Vietnam, Indonesia), Hawaii, Moorea and other sites are sampled. This results in a comparison of different types of fish, ecosystems (stressed / unloaded) and cultivation methods (aquaculture management of commercial groupers) and the dangers of parasites for their environment.

We are developing methods to use parasites as bioindicators: potential taxa are tested, evaluated and applied by using parasites of comparable fish species or sites. In this context, it is also possible to determine host-animal and species-community interactions, and ecosystem health (natural or cultural system) by means of long-term monitoring (pollution, climate change). Worms are analyzed by means of pyrolysis field ionization mass spectrometry, molecular-chemically, for pollutants in the ecosystem, since they accumulate 100 times more than, e.g. fish hosts. The further developed "Star-Graph" visualizes results and represents them decision makers of different economic sectors.