Green Infrastructure and Water Quality in the Wadden Sea under Future Changes in Climate

On Thursday, May 16 at 9:30, Sara Pino Cobacho will defend her master‘s thesis in Coastal and Marine Management. Her thesis is titled, Green Infrastructure and Water Quality in the Wadden Sea under Future Changes in Climate. The thesis presentation takes place at the University Centre of the Westfjords and is open to the public.

The thesis first advisor is Dr. Ghada El Serafy, Specialist in Data Assimilation, Data Sciences and Applied Informatics at Deltares an independent institute for applied research in the field of water and subsurface in the Netherlands. The second advisor is Dr. Zoi Konstantinou, Policy Officer at the Directorate for Maritime Affairs, European Commission. The external reader is Dr. Pamela Woods, Fisheries Scientist at the Icelandic Marine and Freshwater Research Institute.


Natural shellfish reefs act as Green Infrastructure by protecting the coastline while respecting the natural functioning of the ecosystem. Yet, their efficiency is surrounded by uncertainty when they are subject to Climate Change-related stressors. Identifying their vulnerabilities when exposed to changing water conditions is fundamental to identify the best circumstances for an efficient application of these reefs. An ecological modelling approach enabled the simulation of several future climate scenarios for the Dutch Wadden Sea. Concentrations of dissolved oxygen, nitrate, orthophosphate and Chlorophyll-α were assessed, as well as shellfish biomass as this variable reflected the two-way relationship between the reefs and environmental conditions. The model included Mytilus edulis and Crassostrea gigas, the two dominant reef-forming species in the Dutch Wadden Sea. Orthophosphate concentrations were found to be significantly affected by changes in river outflows increasing up to 25% under RCP8.5, whereas no significant changes in nitrate concentrations were obtained due to high denitrification rates. Irradiance was the main limiting factor for primary production that resulted to be significantly impacted by climate change at most of the monitoring sites. These impacts do not only involve changes in abundance and distribution of phytoplankton but also disturbances to the general pattern of primary productivity. Dissolved oxygen levels were found not to be an issue in the coming years as this variable was not very sensitive to environmental changes. The distribution of shellfish was highly dependent on food availability which caused an eastern migration of these species in search of phytoplankton. In light of these findings, coastal protection strategies that use Green Infrastructure cannot only rely on shellfish reefs as a long-term measure as their continuity in the current locations may vary in the future. This situation would be aggravated in the high emission scenarios, leading to a faster migration of the reefs and an increasingly vulnerable coastline. Shellfish would not only depend on primary producers to survive but they would also provide them with a physical shelter thus enhancing primary production rates. Because of this two-way relationship between the shellfish, water quality and ecology, the presence of reefs is proven to influence the state of the environment. In order to compensate for the vulnerability caused by reef migration, the deployment of a complementary coastal management option would be necessary. Thus, shellfish reefs could not be implemented as a single measure to appropriately cover the protection requirements of a vulnerable coast.

Sara Pino Cobacho defends her masters thesis on water quality in the Wadden Sea.