RIVER FISH RESEARCH

It has always been a dream for me to carry out my own PhD research on fish ecology and behaviour. When the opportunity came along to do a PhD at the Aquaculture and Fisheries chair group at ‘my own’ Wageningen University, I had to board that ship. Even if that meant to leave my relaxing life in Bonaire (Dutch Caribbean) behind and move back to the Netherlands. I started this 4-year PhD research in July 2017 and below you can find a short description of my research.

Problem: The river Rhine has been extensively modified throughout history, which resulted in the decline or loss of many of its original flora and fauna. Despite recent changes in ecological perception and the subsequent positive changes to water quality and habitat variability, the ecological quality of the river Rhine is still poor. Especially the recovery of rheophilic fish species, an indicator for good ecological quality, remains below expectations. We expect that the (slow) recovery pattern of these rheophilic fish populations is mainly caused by insufficient presence and accessibility of habitats that function as nursery area for rheophilic fish.

Objectives: The main objective of this PhD research is to assess the temporal and spatial use of diverse habitats by juvenile rheophilic fish in the aquatic-terrestrial transition zones in the floodplains along the lower river Rhine. The project focusses on the underlying processes of recruitment dynamics of rheophilic fish in relation to habitat complexity and food availability.

Approach: Over a period of 3 years (2017-2020), floodplain water bodies along the lower River Rhine will be sampled to assess the relation between rheophilic fish recruitment and their habitat. Sampling will focus on floodplain systems within the management area of Rijkswaterstaat Oost-Nederland (RWS-ON) in the Netherlands: IJssel, Waal, Nederrijn and Lek. Sampling will mainly focus on recently created floodplain systems (secondary channels and oxbow lakes). For comparison, the main river (river banks and groyne fields) will also be included in the sampling process. The sampled water bodies vary in morphology and hydrological characteristics, such as: substratum, vegetation, slopes of shorelines, depth, flow velocity and connectivity. Some of the water bodies will have a permanent connection to the main channel, whereas others will only be connected during floods. In the summer of 2017 (between 10 July and 7 August), juvenile fish communities have been sampled in 59 river-floodplain locations.

In addition to the extensive 3-year fieldwork, a more in-depth fieldwork approach is chosen to investigate the recruitment dynamics of juvenile rheophilic fish within a floodplain system. Four potentially interesting locations are chosen from the 2017 dataset as study area for the period 2018-2020. Locations will be monitored from March until October, the ‘nursery season’ for (rheophilic) fish in the river Rhine. Locations will be monitored throughout the season with permanent measuring equipment (habitat complexity and water quality) and fish/habitat will be monitored on a weekly basis. Most of the fieldwork and analysis will be done by MSc, BSc and HBO students in collaboration with PhD student.

For more information on this research you can contact me.

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