MSc thesis topic: Using Remotely Sensed data to map development in seagrass fields over time along the North Sea coasts

Seagrass provides very important habitat including nursery ground for many marine species. In the Netherlands, extensive seagrass fields could be found in The Wadden Sea area and the province of Zeeland. Although the larger Wadden Sea area still supports the largest intertidal seagrass bed in Europe (Dolch et al. 2017), in The Netherlands hardly any seagrass is left since the tremendous declines in the 1930s and 1970-1980s (Dolch et al. 2013). The remaining seagrass beds in the UK and Denmark still provide the ecological function for the North Sea ecosystem that the Netherlands also profits from. However, seagrasses in the UK are also in serious decline for several reasons. In the Netherlands some (very) small scale restoration projects are ongoing, and from such introductions seagrass could recover if given the opportunity on suitable locations. Previous studies have demonstrated that seagrasses are visible using remotely sensed imagery for example from the Landsat and Sentinel satellites (Barillé et al. 2010; Kohlus et al. 2020).

In this study the student will first use Landsat imagery to identify the signal of sea grasses for known areas of seagrass, for example in the larger Wadden Sea area and along the British coast. Next, we will extend the methodology and generate biannual seagrass maps for the North Sea coast to identify developments in seagrass loss and recovery. Lastly, we will link (historical) presence of seagrass with existing data on sea depth, salinity, and current strength to be able to predict where along the Dutch coast (especially the Wadden Sea as well as Zeeland) the conditions would be suitable for seagrass restoration efforts.

Relevance to research/projects at GRS or other groups

This project is a collaboration with the Marine Animal Ecology (MAE) group of Wageningen University.

Objectives and Research questions

• What is the spectral signal of seagrasses in the North Sea?
• What are the spatial developments of seagrasses along the North Sea coasts over the last twenty (and preferably more) years?
• What is the spatial relation between seagrass occurrence and sea depth, salinity, and current strength?
• What locations would be suitable for future seagrass habitats?

Requirements

• At least Intro to Remote Sensing
• Experience or interesting in the processing of satellite image time series
• Geoscripting
• Interest and affinity for marine environments

Literature and information

• Barillé, Laurent, Marc Robin, Nicolas Harin, Annaëlle Bargain, and Patrick Launeau. "Increase in seagrass distribution at Bourgneuf Bay (France) detected by spatial remote sensing." Aquatic Botany 92, no. 3 (2010): 185-194.
• Dolch, Tobias, Christian Buschbaum, and Karsten Reise. "Persisting intertidal seagrass beds in the northern Wadden Sea since the 1930s." Journal of Sea Research 82 (2013): 134-141.
• Dolch T., Folmer E.O., Frederiksen M.S., Herlyn M., van Katwijk M.M., Kolbe K., Krause-Jensen D., Schmedes P. & Westerbeek E.P. (2017) Seagrass. In: Wadden Sea Quality Status Report. Eds.: Kloepper S. et al., Common Wadden Sea Secretariat, Wilhelmshaven, Germany. Last updated 21.12.2017. Downloaded 20.04.2023. qsr.waddensea-worldheritage.org/reports/seagrass Kohlus,
• Jörn, Kerstin Stelzer, Gabriele Müller, and Susan Smollich. "Mapping seagrass (Zostera) by remote sensing in the Schleswig-Holstein Wadden Sea." Estuarine, Coastal and Shelf Science 238 (2020): 106699.
• Eelke O. Folmer, Justus E.E. van Beusekom, Tobias Dolch, Ulf Grawe, Marieke M. van Katwijk, Kerstin Kolbe and Catharina J.M. Philippart (2016) Consensus forecasting of intertidal seagrass habitat in the Wadden Sea, Journal of Applied Ecology 2016, 53,1800–1813.

Expected reading list before starting the thesis research

• See above

Theme(s): Sensing & measuring; Integrated Land Monitoring