Adding ecological value to the subtidal zone of dikes
Many dikes in the Netherlands need reinforcement to comply with the safety standards in times of climate change. In the subtidal part of the dike traditionally weak parts are reinforced with a layer of steel slag of riprap. At several locations in the Eastern Scheldt ridges of riprap have been or will be applied in the subtidal zone. These intend to trap sediment, ensuring the surrounding steel slag or riprap is covered by sediment, thereby bringing back the original sandy/muddy habitat. The goal is to preserve this habitat which is an important precondition for the reinforcement of of coastal defence structures in this Natura 2000 area. There are indications that the flora and fauna that develop on the ridges might ‘seed’ the surrounding habitat. Many local species that are found on soft habitats are known to use hard structures for eg refuge or shelter. Therefore the ridges may contribute to the biodiversity of target species of sandy or muddy habitats while at the same time providing an habitat for eg. commercial species like lobster. This will be tested in a large-scale lab facility at NIOZ-Yerseke. In 12 large basins (length x width x depth: 7,5x3x2m) the development on test ridge sections and their surrounding sandy bottom will be monitoring with a variety of techniques, including: camera-observations with gopro or underwater drone and sampling+determination of species present. Several techniques will be tested to monitor mobile species.
Research type: field research, desk analysis
Research level: project level, e.g. Water management students and/or Civil engineering students; minor, internship or graduation bachelor thesis project.
Prerequisite: interest in marine ecology, good snorkeling skills, driver's license preferred.
Partners: NIOZ, Rijkswaterstaat
Client: Tim van Oijen (HZ)
