An international group of researchers, coordinated by Professor of Genetics of the University of Oviedo, Eva García Vázquez, has pioneered the application of massive sequencing of environmental DNA to monitor invasive marine species that survive in ballast waters discharged by large ships. The prestigious journal Marine Pollution Bulletin has published the results of the study carried out on the basis of the data collected during a journey from the port of Bremen in Germany to Cape Town in South Africa.

These works, developed in the framework of the research lines of the Marine Observatory of Asturias, and promoted by the Cluster of Energy, Environment and Climate Change of the Campus of International Excellence, are carried out on the German research ship Polarstern. Students and professors of the Erasmus Mundus Master Programme in Marine Biodiversity and Conservation joined this journey, which lasted one month.

The team took samples of the ballast water of Polarstern, a German ice-breaker ship devoted to research, in order to monitor the organisms that survived day after day, and those that could handle temperature changes, oxygen changes, etc. The ballast waters that large cargo ships to guarantee their balance are nowadays the quickest way to have marine organisms spread out, as they take it in one port and discharge it in a place with a totally different marine biodiversity.

DNA extraction and massive sequencing of all the samples were performed with last generation technologies in the laboratories of the scientific-technical services of the University of Oviedo. All the data assembled resulted in thousands of DNA sequences, whose taxonomic analyses were developed taking into account two genetic markers: one for animals, and another one for plants and algae in this case. The results were compared to the data collected through the taxonomic identification of visu, under a microscope, which was carried out on board.

The journal Marine Pollution Bulletin has published the work developed by an international team, led by Professor Eva García Vázquez at the University of Oviedo, and Dr. Anastasija Zaiko at the University of Klaipeda (Lithuania), to test a new techniques to reduce biological invasions.

This pioneering technique allows us to save time when developing monitoring processes of the marine biodiversity, as it is easier and quicker than the visual counting of all the samples. The environmental DNA sequencing clears up some ambiguities when identifying different individuals, and it actually allowed locating certain organisms that could not be identified in the visual counting process.

The distance and variety of the routes followed by large cargo ships that bring ballast waters in their hold, allow hundreds of species to travel from their original habitat to places with a different biodiversity. These journeys are usually long and the temperature conditions, amount of oxygen, etc., vary dramatically, so only high-resistant species survive, with a high invasive potential at their destination.

As for the route followed by the Polarstern between Bremen and Cape Town, the temperature of the ballast water reached 30 ºC near the Equator, and the oxygen drastically decreased. Protozoa and some fungi, within animals, and also some red algae, although in less proportion, proved to be the species with the highest survival capacity in a journey that brought them from the waters of the North Sea to the Equator line, which are places with a very different marine biodiversity.

The identification of these species means an essential first step to achieve a better control of the marine biodiversity and stop the biological invasions that are nowadays one of the major environmental problems for oceans. The published article is only the first one of a series of research works.

Research team

Researcher developing this research line from the University of Oviedo:

• Eva García Vázquez, Yaisel Borrel, Alba Ardura (Department of Functional Biology)
• José Luis Martínez Fernández (Scientific Technical Services)
• Daniel Serna Fuente (Scientific Technical Services)

From the University of Klaipeda (Lithuania) and Cawthron Institute (New Zealand): Anastasija Zaiko

From the University of Klaipeda: Aurelija Samuiloviene

Julia Schmidt-Petersen (Ghent University, Belgium) and Deni Ribicic (Norwegian University of Science and Technology, Norwey), also took part in this project.

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German ice-breaker vessel Polarstern dedicated to research. Image: Anastasija Zaiko