PhD defence Pieterjan Verhelst

Friday, December 7, 2018

We are pleased to announce that on Friday 7 October 2018, PhD researcher Pieterjan Verhelst will be defending his PhD dissertation on "European eel (Anguilla anguilla L.) movement behaviour in relation to habitat fragmentation - Novel insights inferred from acoustic telemetry". This PhD is promoted by prof. dr. ir. Peter Goethals, prof. dr. Tom Moens, dr. ir. Ans Mouton and dr. Jan Reubens. Below you can find a short abstract of the research. The defence starts at 17:00 and takes place at Auditorium A3, building S9, Campus Sterre (Krijgslaan 281, 9000 Ghent). Adjacent the reception will take place at 19:00 at the Kleine Leszaal, building S8.

An ever increasing human population has led to global change, resulting in substantial pressures on ecosystems and diversity loss by (in general) acting on five fronts: (a) climate change, (b) habitat modifications resulting in habitat loss and fragmentation, (c) biogeochemical and hydrological cycles and pollution, (d) biological invasions, and (e) overexploitation of natural resources. Consequently, maintaining species diversity and ecosystem functioning will increasingly require human intervention by adequate management. Aquatic environments are among the most anthropogenically altered systems. Impact often results in changed hydrological conditions due to land reclamation, agricultural drainage, shipping accompanied with shipping locks, waste water treatment and hydropower. Obviously this affects aquatic life, among them fish species. A flagship fish species affected by global change, is the European eel (Anguilla anguilla L.). Its spawning grounds are assumed to be in the Sargasso Sea, after which the leptocephalus larvae drift with the Gulf Stream to continental Europe and metamorphose into glass eels. It is this stage which settles in coastal, estuarine and freshwater habitats to grow as yellow eels. Once they reached a certain size and accumulated enough fat, they migrate back to the spawning site as silver eels. Yet, over the last four decades, their glass eel recruitment numbers have plummeted by 90 – 99%, leading to the ’critically endangered’ IUCN Red List status. This worrisome decline resulted in the adoption of the EU Eel Regulation in 2007 which states that European countries need to take management measures to ensure 40% escapement of the spawning stock biomass, defined as the best estimate of the theoretical escapement rate if the stock were completely free of anthropogenic influences. However, as all five components of global change affect the European eel population, taking effective measures is not straightforward. Consequently, to partly cover this knowledge gap, habitat quality and connectivity were the central focus of this dissertation. Connectivity between freshwater habitats and marine areas is heavily obstructed by anthropogenic structures (e.g. weirs, pumping stations, shipping locks, sluices...), leading to a high pressure on the European eel population. A better understanding of fish migration behaviour in relation to these barriers is needed to take proper mitigation actions. To understand eels’ habitat use, we applied acoustic telemetry to reveal their movement behaviour in various aquatic systems and habitat types.