Linking Opportunities to the Water Framework Directive and Natura 2000

Linking opportunities to the Water Framework Directive and Natura 2000

Research into the developments that can serve the goals of the Water Framework Directive and Natura 2000 at the Eastern Scheldt and Lake Grevelingen.

Final thesis Tess van der Hulle

6-6-2019

Linking opportunities to the Water Framework Directive and Natura 2000

Author: Tess van der Hulle 71647 Bachelor Delta Management HZ University of Applied Sciences

In-company mentor: Thijs Poortvliet Rijkswaterstaat Zee & Delta

First examiner: Pierre Bleuzé HZ University of Applied Sciences

Second examiner: Jasper van den Heuvel HZ University of Applied Sciences

Place: Middelburg, The Netherlands

Date: 6-6-2019

Summary

Rijkswaterstaat has an effort-obligation and result-obligation to take measures to achieve the goals of the Water Framework Directive (WFD) at the Eastern Scheldt and Lake Grevelingen. The WFD aims to achieve and protect a sufficient ecological and chemical status of inland surface waters, transitional waters, coastal waters and ground water. Preparations have started to take measures for the third cycle (2022-2027). Furthermore, Rijkswaterstaat is responsible for the conservation of the favourable status of the Natura 2000 (N2000) areas Eastern Scheldt and Lake Grevelingen. N2000 is a network of nature areas of European importance, aiming to safeguard Europe’s biodiversity by implementing the goals of Bird Directive and Habitats Directive.

Water defences have affected the water quality of water bodies negatively. Furthermore, habitats of plants and animals have been modified or lost. Yet, the ecological goals of the WFD and N2000 must be met. Stakeholders and managers of the Eastern Scheldt’s and Lake Grevelingen’s ecological values are taking measures to improve the areas’ ecology. However, initiatives are not always linked to the WFD and N2000, while these measures could serve the goals, which lead to the following research question:

Which opportunities can serve the goals of the Water Framework Directive and Natura 2000 in the Eastern Scheldt and Lake Grevelingen while not deteriorating water safety?

For the collection of data, the methods of desk research and consultation are used. An initiative is considered an opportunistic measure if the initiative contribute to the favourable status of the WFD and N2000 goals and does not deteriorate water safety.

According to the WFD goals, the Eastern Scheldt’s ecology requires improvement on the quality element of ‘other aquatic flora’. Lake Grevelingen’s ecology requires improvement on the quality elements of ‘other aquatic flora’, ‘macrofauna’ and ‘fish fauna’. According to the N2000 goals, the Eastern Scheldt’s goals for habitat types and species, coastal breeding birds and ducks, geese and swans are not realized. Stilts might nog be realized in the future. Lake Grevelingen’s goals for habitat species, coastal breeding birds, marsh breeding birds, fish-eating birds and ducks, geese and swans are not met. Habitat types might not be realized in the future.

The opportunities-map on the next page provides an overview of ambitions and initiatives of stakeholders at the Eastern Scheldt and Lake Grevelingen that have been assessed as an opportunistic measure for the implementation of the WFD and/or N2000. In addition, opportunistic location for the implementation of new measures are provided. By including the initiatives in the WFD River Basin Management Plan Scheldt and N2000 Management Plan, the initiatives can become official WFD and N2000 measures.

III

Table of content 1. Introduction ...... 1 1.1 Background ...... 1 1.2 Problem statement ...... 1 1.3 Research objective ...... 2 1.4 Research question ...... 3 1.5 Readers guide ...... 3 2. Theoretical framework ...... 4 2.1 Research areas...... 4 2.1.1 Eastern Scheldt ...... 4 2.1.2 Lake Grevelingen ...... 4 2.2 Water Framework Directive ...... 5 2.2.1 Management ...... 5 2.2.2 Categorization of water bodies ...... 5 2.2.3 Goals ...... 6 2.2.4 References and scales Eastern Scheldt and Lake Grevelingen ...... 6 2.3 Natura 2000 ...... 7 2.3.1 Management ...... 7 2.3.2 Goals ...... 8 2.3.3 Conservation goals for Eastern Scheldt and Lake Grevelingen ...... 8 2.4 Conceptual framework ...... 9 3. Method ...... 10 3.1 Research design ...... 10 3.2 Data collection ...... 10 3.2.1 Desk research ...... 10 3.2.2 Consultation ...... 11 3.3 Analysis of results ...... 11 4. Results ...... 12 4.1 Status WFD ...... 12 4.1.1 Eastern Scheldt ...... 12 4.1.2 Lake Grevelingen ...... 13 4.2 Status N2000 ...... 13 4.2.1 Eastern Scheldt ...... 14 4.2.2 Lake Grevelingen ...... 14 4.3 Criteria for assigning measures ...... 15 4.3.1 WFD ...... 15

4.3.2 N2000 ...... 16 4.4 Assessment of initiatives ...... 16 4.4.1 Sand supplementation (Eastern Scheldt) ...... 17 4.4.2 Hard salt marsh defences (Eastern Scheldt)...... 18 4.4.3 Shellfish reefs (Eastern Scheldt) ...... 19 4.4.4 Seven-island plan (Eastern Scheldt) ...... 21 4.4.5 Nature compensation (Eastern Scheldt) ...... 23 4.4.6 Aquatic nature reserve (Eastern Scheldt)...... 24 4.4.7 Reintroduction of tide (Lake Grevelingen) ...... 24 4.4.8 Reintroduction of seagrass (Lake Grevelingen) ...... 27 4.4.9 Bird islands (Lake Grevelingen) ...... 29 4.4.10 Waddenmozaïek ...... 30 4.4.11 Island Griend ...... 31 5. Discussion ...... 33 5.1 WFD ...... 33 5.2 N2000 ...... 34 5.3 Assessment of initiatives ...... 34 6. Conclusion & Recommendations ...... 36 6.1 Sub questions ...... 36 6.2 Research question ...... 38 6.2 Recommendations...... 39 7. References ...... 41 Appendix 1: Background on research areas ...... 50 A1.1 Eastern Scheldt ...... 50 A1.1.1 Management ...... 50 A1.1.2 Water network ...... 50 A1.1.3 Pressures ...... 50 A1.2 Lake Grevelingen ...... 52 A1.2.1 Management ...... 53 A1.2.2 Water network ...... 53 A1.2.3 Pressures ...... 53 Appendix 2: Background on the WFD and N2000 ...... 55 A2.1 Water Framework Directive ...... 55 A2.1.1 Management ...... 55 A2.1.2 Categorization of water bodies ...... 56 A2.1.3 Goals ...... 56

A2.1.4 Quality elements per type of surface water body ...... 57 A2.2 Natura 2000 ...... 59 A2.2.1 Management ...... 59 A2.2.2 Goals ...... 60 Appendix 3: WFD References and scales ...... 62 A3.1 K2...... 62 A3.1.1 Biology ...... 62 A3.1.2 Hydro morphology ...... 63 A3.1.3 Physical chemistry ...... 63 A3.2 M32 ...... 64 A3.2.1 Biology ...... 64 A3.2.2 Hydro morphology ...... 65 A3.2.3 Physical chemistry ...... 65 A3.3 Pollutants ...... 65 A3.4 Ubiquitous substances ...... 65 Appendix 4: N2000 Conservation goals and status of research areas ...... 66 A4.1 Eastern Scheldt ...... 68 A4.2 Lake Grevelingen ...... 74 Appendix 5: List of stakeholders ...... 79 Appendix 6: Results and status of WFD quality elements of research areas ...... 81 A6.1 Eastern Scheldt ...... 82 A6.1.1 Physical chemistry ...... 82 A6.1.2 Priority substances ...... 82 A6.1.3 Ubiquitous substances ...... 82 A6.1.4 Biology ...... 83 A6.2 Lake Grevelingen ...... 84 A6.2.1 Physical chemistry ...... 84 A6.2.2 Priority substances ...... 84 A6.2.3 Ubiquitous substances ...... 84 A6.2.4 Biology ...... 85 Appendix 7: Overview of WFD measures ...... 86 Appendix 8: Consultation ...... 87 A8.1 Eastern Scheldt ...... 87 A8.2 Lake Grevelingen ...... 88 A8.3 WFD ...... 89 A8.4 N2000 ...... 92

A8.5 Tides Lake Grevelingen ...... 92 A8.6 Intertidal areas ...... 93 A8.7 Seagrass ...... 93 A8.8 Shellfish reefs ...... 94 A8.9 Bird islands ...... 95 A8.10 Seven-island-plan ...... 95 A8.11 Wadden mozaiek and Griend ...... 96 A8.12 Ambitions Natuurmonumenten ...... 96 A8.13 Ambitions Oosterscheldevisie ...... 96 A8.14 Overall research ...... 97

VII

1. Introduction This research report is part of the final thesis for the fourth year study of Delta Management at the HZ University of Applied Sciences. The research assignment is provided by Rijkswaterstaat Zee & Delta, as part of an internship. In this chapter, the research topic is introduced. The statement of the research problem is given and the research objective is described. This results in the research question that will be answered in the report. To conclude, a readers guide is provided. 1.1 Background Rijkswaterstaat is currently working on the improvement of ecological water quality, in order to meet the goals of the European Water Framework Directive. The Water Framework Directive (WFD) aims to achieve and protect a sufficient status of inland surface waters, transitional waters, coastal waters and ground water (Witteveen+Bos, Royal Haskoning DHV, Colibrie Advies, & Twynstra Gudde, 2018a). During the Water Conference in 1996, the European Commission concluded that water protection should become a priority within the European Water Policy, which resulted in a proposal for a WFD (European Parliament and the Council, 2000). The Directive, published in 2000, sets standards in both ecological and chemical water quality of all surface waters, which have to be achieved within a deadline. Member States of the European Union are required to perform monitoring and assessment on their water bodies and assign qualified authorities to apply the goals of the WFD (European Parliament and the Council, 2000). Member States identify national (and possibly transboundary) river basins districts and compose a River Basin Management Plan for each cycle of the WFD (Witteveen+Bos, et al., 2018a). Each cycle takes six years, starting in 2010. Currently the measures planned for the second cycle are being executed (2016-2021) and preparation for the third cycle (2022-2027) has started. According to the Directive, Member States are obliged to have achieved the WFD goals for each water body by 2027. Rijkswaterstaat’s regional department ‘Zee & Delta’ is responsible for the application of the WFD goals in Zeeland, containing the river basin ‘Scheldt’.

The European Union has developed another method for the protection and conservation of ecosystems, in addition to the WFD (Ministerie van Infrastructuur en Milieu, 2015). Natura 2000 (N2000) was established, existing of a network of nature areas of European importance (Ministerie van Landbouw, Natuur en Voedselkwaliteit, 2006). The network puts a protection status on the N2000 areas, with its main purpose to safeguard European biodiversity. The N2000 status is designated to nature areas that meet the criteria of the EU Habitats Directive (1992) and the EU Birds Directive (2009) set by the European Union. The EU Member States have agreed to conserve a favourable status of the N2000 network by implementing the goals of both the Birds Directive and the Habitats Directive (Ministerie van Landbouw, Natuur en Voedselkwaliteit, 2006). These goals are described as conservation objectives, existing of maintenance, expansion or improvement of present natural values, while still allowing sustainable use (Ministerie van Infrastructuur en Milieu, 2015). In the Netherlands, the goals are executed via management plans written for each nature area, following the same cycles of six years as the WFD (Rijkswaterstaat, 2016a). 1.2 Problem statement The Netherlands’ water system has been severely adapted, in order to protect the low-lying areas from flooding (Ministerie van Infrastructuur en Milieu, 2015). Water defences, like dikes and storm barriers, have affected the water quality of water bodies negatively. In addition, habitats of plants and animals have been modified or lost. Restoring river basins to its original state is impossible, since flooding will have extreme effects on the land and its inhabitants. Yet, the ecological water quality must meet the standards set by the EU WFD.

The ecological and chemical state of water bodies have been monitored and tested. The WFD goals for each water body must be met before the end of the third cycle (2027). In order to know the status of a water body, the measurements of the monitoring programme and the standards for a sufficient ecological and chemical state must be analysed. In addition, the monitoring results of habitats and birds must be compared to the N2000 goals. In order to improve the status of an area, measures are being executed by different stakeholders in the second cycle. In addition, projects with other purposes than the WFD and N2000 might still affect the achievement of goals, providing opportunities to link an initiative to the WFD and N2000. Furthermore, new techniques or measures taken in comparable situations might be applicable to improve the current status and meet the WFD and N2000 goals.

According to the National WFD Team (2018), Rijkswaterstaat is obliged to take measures in order to improve the insufficient scores of a water body’s status. As a result, the research problem is stated. Firstly, a clear and practical overview of the current state of water bodies according to the WFD and N2000 criteria is lacking. Secondly, inefficient communication within and amongst organisations is causing missed opportunities of initiatives that can be linked to the WFD and N2000. Projects executed by organisations onsite might unknowingly contribute to the goals of the WFD and N2000, or provide opportunities when adjustments are made. Thirdly, assessment of the results of projects executed is lacking. Furthermore, the connection between WFD and N2000 status of water bodies and possible measures is hardly made. To conclude, a complete overview of opportunities that can serve both the WFD and N2000 is lacking, while the deadline is approaching. Action is needed to meet the goals in time, yet the opportunities present to do so are still unknown.

Although the problem statement involves all water bodies located in Zeeland, this research will focus on the water bodies Eastern Scheldt and Lake Grevelingen, as assigned by Rijkswaterstaat Zee & Delta. The areas face pressures, for which solutions and their effects are part of a very topical discussion. Both areas are part of the N2000 network and WFD, located in the Scheldt river basin district. Both areas have been modified from its natural state for the improvement of water safety, affecting the quality of water, habitat and species. According to Rijkswaterstaat (2018), the status of the Eastern Scheldt and Lake Grevelingen is insufficient by the standards of the WFD. Furthermore, Rijkswaterstaat (2016b+c) states that further conservation measures are necessary to achieve the N2000 conservation objectives. Rijkswaterstaat Zee & Delta is facing the issue of result-obligation towards the directives, while an overview of the status and opportunities is lacking. In addition, measures may not affect water safety aspects negatively. 1.3 Research objective The current status of the Eastern Scheldt and Lake Grevelingen is insufficient by the standards of the WFD and N2000. In order to achieve a sufficient state, improvements must be made before the end of the third cycle. Concluding from the problem statement, the following vision for the research areas Eastern Scheldt and Lake Grevelingen is stated:

The Eastern Scheldt and Lake Grevelingen have a sufficient status according to the goals of the Water Framework Directive and Natura 2000. Opportunities to improve the status are explored in a situation where public and private stakeholders communicate efficiently and participate to conserve and manage the sufficient status of the water quality, habitat and species, while still allowing sustainable use of the areas. The implementation of WFD and N2000 measures does not affect water safety negatively.

This research will contribute to the integrated vision stated, by exploring which opportunities can contribute to the goals of the WFD and N2000. The research objective is to provide Rijkswaterstaat with:

 Insight in the method the WFD and N2000 uses for measuring the status of a water body;  Understanding of the status of the research areas according to the WFD and N2000 goals;  Insight in stakeholders’ contributions to the WFD and N2000 goals;  Insight in opportunities that serve the WFD and N2000 goals and their effect on water safety.

The research will result in an advise consisting of an opportunities-map, providing an overview of opportunities for the research areas. The map illustrates what improvements can be made to reach the WFD and N2000 goals in the current situation; what is going to be implemented by stakeholders of the problem; what ambitions do stakeholders have; what adjustments can be made to existing projects and what new measures could be implemented.

In the research, measures are assessed according to criteria set by the National WFD Team. The coordinator and the regional project team determine whether the content of the measures forms an opportunity that can be executed. Subsequently, a request is made at the National WFD Team. If approved, the process starts with an assignment-letter that orders the means to execute the measure. For this reason, the research contributes to the stated vision, since the advice may result in the execution of an opportunistic measure. The measure might improve the status of a water body, contributing to the obligation to reach the desired status of a water body. 1.4 Research question In order to achieve the research objective, the report will focus on one research question. This research question is:

Which opportunities can serve the goals of the Water Framework Directive and Natura 2000 in the Eastern Scheldt and Lake Grevelingen while not deteriorating water safety?

In order to answer the main research question, four sub questions are formulated. These sub questions are:

1. What is the current status of the Eastern Scheldt and Lake Grevelingen according to the goals of the WFD and N2000? 2. What are the criteria for the WFD and N2000 and how can they be linked to independent projects? 3. What initiatives are in development that could be linked to the goals of the WFD & N2000 at the Eastern Scheldt and Lake Grevelingen by Rijkswaterstaat and other stakeholders? 4. Will the initiatives deteriorate water safety? 1.5 Readers guide Firstly, the theoretical framework is described in Chapter 2. The chapter forms the foundation of the research, existing of theory, definitions and relevant studies into the research subject. Chapter 3 describes the method of the research, including the approach for answering the research question. Chapter 4 provides the results of the execution of the method. In Chapter 5, the results are discussed. To conclude, in Chapter 6, the research question is answered and recommendations are given.

2. Theoretical framework This chapter provides the theory behind the research topic. The framework serves as an expansion of the problem statement, providing a basis for understanding the results of this research. Firstly, a short background to the research areas is described. Secondly, the WFD and N2000 goals are explained. Definitions of terms providing a better understanding of the research problems are included. To conclude, a conceptual framework is provided, showing the connections between all aspects of the theoretical framework. 2.1 Research areas Both the Eastern Scheldt and Lake Grevelingen are part of the Scheldt river basin (Rijkswaterstaat, 2018). The research areas contain natural values of national and international importance. Therefore, the areas are part of the N2000 network and WFD (Rijkswaterstaat, 2016b+c). Flood defences, the water system and infrastructural works are managed by Rijkswaterstaat and water board(s). The Delta Works, serving as flood defences, have influenced the characteristics of the Eastern Scheldt and Lake Grevelingen. Below, the most relevant matters are summarized. More elaborate information on the research areas can be found in Appendix 1. 2.1.1 Eastern Scheldt The Eastern Scheldt is categorized as coastal water (Rijkswaterstaat, 2018). According to Rijkswaterstaat (2016b), the most important functions at the Eastern Scheldt involve shipping and nature. The research area is shown in Figure 1. The water body has a surface of 350 km2 (Rijkswaterstaat, sd.a). The Eastern Scheldt is connected with adjacent water bodies via ship locks and sluices in dams (Rijkswaterstaat, 2016b). Due to the Eastern Scheldt Storm Surge Barrier and dams surrounding the water body, tidal currents declined with thirty percent (Van Zanten & Adriaanse, 2008). As a result, intertidal areas are eroding, its sediment filling tidal channels. The process is called ‘sandhunger’, which results in the loss of sand banks and tidal flats (and consequently loss of salt marshes, having mostly a negative effect on nature, and little negative effects on dike safety, shipping, recreation and (shell)fishing (Witteveen+Bos, 2011). Sandhunger is pressuring the N2000 and WFD goals.

Figure 1 The location of the Eastern Scheldt is shown on the map by the blue-marked area. The whole area serves as WFD water body and is part of the N2000 network. The Eastern Scheldt is located between the municipalities of Schouwen-Duiveland, Tholen, Reimerswaal, Kapelle, Goes and Noord-Beveland. The other borders to the water body are formed by the Eastern Scheldt barrier, Oesterdam, Philipsdam, Grevelingendam and Zandkreekdam. (Rijkswaterstaat, 2018)

2.1.2 Lake Grevelingen Lake Grevelingen is Europe’s largest salt water lake (Rijkswaterstaat, 2014; Tangelder, et al., 2018). According to Rijkswaterstaat (2016c), the most important functions of Lake Grevelingen involve nature, recreation and (shell)fishing. The research area is shown in Figure 2. The water body has a surface of 140 km2 (Rijkswaterstaat, sd.b). The lake is connected with adjacent water bodies via a ship lock and sluices in its dams (Rijkswaterstaat, 2016c). Due to the Brouwersdam and Grevelingendam surrounding the water body, the lake has no tidal action (Bouma, et al., 2008). As a result, Lake Grevelingen’s deep water layers are suffering from oxygen deficiency and stratification (Turlings, et al., 2009). Furthermore, missing tidal action and a set water level are affecting the lake’s

4 ecosystem negatively (Hoeksema, 2002). Lake Grevelingen’s issues are pressuring the N2000 and WFD goals.

Figure 2 The location of Lake Grevelingen is shown on the map by the blue-marked area. The whole area serves as WFD water body and is part of the N2000 network. The lake is located between the municipalities of Schouwen-Duiveland and Goeree-Overflakkee. The other borders are formed by the Brouwersdam (west) and Grevelingendam (east). (Rijkswaterstaat, 2018)

2.2 Water Framework Directive The European Water Framework Directive (WFD) aims to achieve and protect a sufficient state of inland surface waters, transitional waters, coastal waters and ground water (Article 1, WFD, European Parliament and the Council, 2000). The European Union provides its Member States with a Directive for goals, monitoring of water quality and taking measures. The goal of the WFD is to achieve a sufficient ecological and chemical status of all waters. The EU Member States have result- obligation and effort-obligation to take measures to reach the WFD goals. Furthermore, detoriation of the status of all water bodies must be prevented (art. 4, WFD).

This paragraph mainly adressess surface waters, since the research areas are surface waters. Ground water plays a minor role. 2.2.1 Management The implementation of the WFD involves multiple governmental organisations (Witteveen+Bos, et al., 2018a). Rijkswaterstaat is is responsible for the management and implementation of the WFD. EU Member states are required to translate the WFD goals into national legislation for implementation purposes (art. 24, WFD). The WFD is included in the Dutch law by the ‘Decree on Quality Standards and Monitoring for Water 2009’ (Bkmw, 2009). EU Member States identify national (and possibly transboundary) river basin districts, for which they ensure appropriate administrative arrangements (art. 3, WFD). Member States ensure the production of River Basin Management Plans (RBMP) (art. 13, WFD). A RBMP includes technical characteristics of the water bodies located in the river basin, the goals, measures and motivation for possible delays and exceptions for the achievement of the WFD goals per cycles of six years. Currently the measures planned for the second cycle are being executed (2016-2021) and preparation for the third cycle (2022-2027) has started (Witteveen+Bos, et al., 2018a). Besides RBMPs, Member States are required to produce programmes that monitor the water status of water bodies within a river basin district, which provide an overview of the water status (art. 8, WFD). The management of the WFD is described more elaborately in Appendix 2 (paragraph A2.1.1). 2.2.2 Categorization of water bodies A river basin exists of several water bodies. EU Member States have to analyse the characteristics of a river basin district, review the environmental impact of human activity and perform an economic analysis of the water use (art. 5 WFD). In order to do so, Member States must identify the location and boundaries of all surface water bodies and ground waters and categorize them (Annex II, WFD). Surface water bodies in their natural state are categorized as rivers, lakes, transitional waters or coastal waters. In addition to the natural state, surface water bodies can be categorized as artificial or heavily modified. A heavily modified water body is a surface water body which is substantially changed in character as a result of physical alterations by human activity (art. 2, WFD). In the

5 categories of natural water bodies, each type has a name and code, which have different goals assigned to the water body type (Elbersen, Verdonschot, Roels, & Hartholt, 2003). More elaborate information on the categorization of water bodies can be found in Appendix 2 (paragraph A2.1.2). 2.2.3 Goals According to the WFD, each water body must achieve a sufficient ecological and chemical water status. For water bodies categorized as natural water bodies, the limit reference for a sufficient water status is the Good Ecological Status (GES) (art. 2, WFD). The limit reference for artificial and heavily modified water bodies is the Good Ecological Potential (GEP), which is derived from the most similar natural water type (Van der Molen, Pot, Evers, & Van Nieuwerburgh, 2012). The highest score possible refers to the High Ecological Status (HES) for natural water bodies and the Maximum Ecological Potential (MEP) for artificial and heavily modified water bodies.

The goal of the WFD is to achieve the GES or GEP for each water body (art. 4, WFD). Furthermore, objective is that detoriation of the status of all surface and ground water bodies is prevented by implementing all necessary measures (art. 4, WFD). In addition, necessary measures are taken to improve the status of water bodies up to the GEP (art. 4, WFD), which may not affect water safety of the area (Rijkswaterstaat, 2018). For the ecological assessment of the WFD, a one-out-all-out principle is used, meaning that all quality elements need to meet the GEP or GES to reach the overall sufficient status (Van der Molen, et al., 2012). The quality elements are divided in differrent categories and differ for each natural water type of surface water (Annex V, WFD), an overview is provided in Appendix 2 (paragraph A2.1.4). For artificial and heaviliy modified surface water bodies, the quality elements of the natural water type that resembles the water body closest are applied.

The biological quality elements are measured in the Ecological Quality Ratio (EQR), which indicactes the distance to the HES and MEP (Van der Molen, et al., 2012). The EQR for HES and MEP is 1, while the GEP and MEP are usually set at 0,6. Furthermore, the WFD includes priority substances and other pollutants that affect the biological quality elements. The pollutants refer to the Environmental Quality Standards (EQS) (European Parliament and of the Council, 2013). The EQS sets the Annual Average (AA-EQS) concentration per substance for inland surface waters and other surface waters. Furthermore, the EQS sets the Maximum Allowable Concentration (MAC-EQS) per substance for inland surface waters and other surface waters.

The deadline for achieving the sufficient status (GES or GEP) of all water bodies is by the end of the third cycle, in 2027 (Witteveen+Bos, et al., 2018a). However the time limit may be extended on the condition that further detoriation is prevented (art. 4, WFD). The WFD offers a possibility for less stringent environmental objectives if the natural condition makes the achievement of the GEP or GET impracticable, disproportionately expensive or if the water body’s characteristics are heavily affected by human activities (art. 4. WFD).

More elaborate information on the WFD goals can be found in Appendix 2 (paragraph A2.1.3). 2.2.4 References and scales Eastern Scheldt and Lake Grevelingen The Eastern Scheldt is classified as K2, which is a coastal water that is protected from heavy tides and wave action, and is part of the polyhaline waters (water with a salinity level between 18 and 30 parts per thousand) (Van der Molen, et al., 2012). Furthermore, the Eastern Scheldt is identified as heavily modified surface water body in the RBMP Scheldt 2016-2021 (Ministerie van Infrastructuur en Milieu, 2015).

Lake Grevelingen is classified as M32, which is a large brackish-to-saline lake. Furthermore, Lake Grevelingen is identified as heavily modified surface water body in the RBMP Scheldt 2016-2021 (Ministerie van Infrastructuur en Milieu, 2015).

The tables in Appendix 3 shows the relevant references and scales for biology, physical chemistry and hydro morphology of the natural water types K2 (paragraph A3.1) and M32 (A3.2). Each biological quality element exists of sub quality elements, from which the final judgement for each quality element is assessed by the overall EQR (Van der Molen, et al., 2012). The scale used for the assessment of biology and physical chemistry of natural water types is shown in Table 1. Each status is corresponding with a value in EQR, including a GES or GEP. Furthermore, the reference for each (sub) quality element is given, from which the values are derived. For the hydro morphological quality elements, the references are given with the corresponding units. For pollutants (priority substances), the EQS for the applicable substances is given (paragraph A3.3) (Ministerie van Infrastructuur en Milieu, 2015). In addition, the EQS and MAC for the relevant ubiquitous substances is given, for which the sufficient or insufficient status is provided (paragraph A3.4) (European Parliament and of the Council, 2013).

Table 1 The WFD scale used for the assessment of the biology, hydro morphology and physical chemistry of natural water bodies. For heavily modified water bodies, the good status (green) is the limit, meaning the status is equal to the GEP or higher. For priority substances and (non)-ubiquitous substances, only the sufficient (blue) or insufficient (red) score is given.

High status / Sufficient Good status Moderate status Moderate status - Bad status / Insufficient Insufficient

By monitoring the different sub quality elements and substances, the status for each element can be assessed. By using the formulas given in Appendix 3, the final judgement for each quality element can be calculated, resulting in the conclusion whether the status is sufficient or not. 2.3 Natura 2000 Natura 2000 (N2000) is a network of nature areas of European importance, aiming to safeguard Europe’s biodiversity (Ministerie van Landbouw, Natuur en Voedselkwaliteit, 2006). The Birds and Habitats Directives for specific N2000 areas serve as the main instruments to achieve this goal, by putting a protection status on birds and habitats, including characteristic species. The Ministry of Agriculture, Nature and Food quality (2006) states that ‘’Member States of the European Union will take all necessary measures to ensure a ‘favourable conservation status’ of species and habitat types of community importance’’. Nature areas are assigned to the network via a Designation Decree (Rijkswaterstaat, 2016a). Consequently, the conservation goals (criteria) for the N2000 area are determined. The N2000 goals do not have a strict deadline, however EU Member States are obliged to commit effort on taking measures that serve the N2000 goals and a vision for 2030 is made. 2.3.1 Management The Dutch Nature Protection Act described the terms of the N2000 area designation, including the area’s conservation goals (art. 2.1, Nature Protection Act, 2019). Conservation goals exist of habitats conserving the birds according to the Birds Directive and habitats conserving the species according to the Habitats Directive (art. 1 Habitats Directive, 1992). The Nature Protection Act requires management plans for each N2000 area (art. 2.3). A management plan follows the same cycles of six years as the WFD (Rijkswaterstaat, 2016a). Management plans describe the area-specific conservation goals, including the necessary conservation measures and their intended results (art. 2.3, Nature Protection Act). These conservation measures are defined as measures taken for preservation, maintenance or re-establishment of the sufficient diversity and area of habitats for all the species of birds applicable to the N2000 area (art. 3, Birds Directive, 2009). Furthermore, the

7 conservation measures correspond with the ecological requirements of the natural habitat types applicable to the N2000 area and avoid deterioration and disturbance of natural habitats and their species (art. 6, Habitats Directive). The measures are the result of assessment of the conservation goals (Rijkswaterstaat, 2016a). Rijkswaterstaat takes the lead in the production of management plans for the Delta waters (Rijkswaterstaat, 2016a). More elaborate information on the management of N2000 can be found in Appendix 2 (paragraph A2.2.1). 2.3.2 Goals According to the Nature Protection Act (2019), N2000 acts on conservation goals, aiming to achieve a favourable status for natural habitats and the population of species of wild fauna and flora of community interest. (art. 1.1 Nature Protection Act; art 2 Habitats Directive). A natural habitat type is of community interest when the territory is endangered, has a small natural range or is a habitat listed in the Directive (art. 1, Habitats Directive). A species is of community interest when the species is endangered, vulnerable, rare or negatively exploited. Bird species applicable to the N2000 are species that are in danger of extinction, vulnerable to change in habitat, rare, or require attention because of the specific nature in their habitat (art. 4, Birds Directive).

For each type of conservation goals named in Table 2, the conservation goals applicable to the N2000 area are assigned (Rijkswaterstaat, 2016a). The Management plan describes the goals and trends, from which the status of habitats and species can be concluded. In the Management plan, the obstacle causing the unfavourable status is described (Rijkswaterstaat, 2016a). Resulting from the assessment, conservation goals can be categorized as maintenance, improvement or expansion of areal, forming the basis for planning the conservation measures to do so. More elaborate information on the N2000 goals can be found in Appendix 2 (paragraph A2.2.2).

Table 2 Types of conservation goals and clusters located in the Delta waters, as described in the Management Plan Delta Waters 2015-2021 (translated from Rijkswaterstaat, 2015).

Type Cluster Breeding birds Coastal breeding birds Marsh breeding birds Non-breeding birds Stilts Fish-eating birds Ducks, geese and swans Birds of prey Habitat species Fishes Plants Mammals Invertebrates Habitat types No clusters

2.3.3 Conservation goals for Eastern Scheldt and Lake Grevelingen In the designation decrees of the Eastern Scheldt and Lake Grevelingen, the boundaries of the N2000 areas are described (see Figure 1 and 2) (Staatssecretaris van Economische Zaken, 2013; Minister van Landbouw, Natuur en Voedselkwaliteit, 2009). Furthermore, the specific species and habitat types for each N2000 area are assigned. For each species or habitat type, the conservation goal is described, including the conservation method: maintenance, improvement or expansion of habitat.

Appendix 4: N2000 Conservation goals provides an overview of all species and habitat types applicable to the Eastern Scheldt (paragraph A4.1) and Lake Grevelingen (paragraph A4.2) according to the Management plan Eastern Scheldt (Rijkswaterstaat, 2016b) and Management plan Lake Grevelingen (Rijkswaterstaat, 2016c). The conservation goal is provided, including an indication

8 whether the conservation goal is met. Furthermore, the trend monitored is shown for the specific area. In addition, the national conservation status (favourable or not) is shown and finally the relative importance of the areas to the national goal is shown.

Analyzing the mentioned data, it can be concluded which conservation goals are met with the current management and which goals face obstacles (the goals are not met). Current management is defined as the complex of measures and activitities implemented in the current situation, relating to the natural value (measures like area management, management and maintenance, law enforcement, communication, mitigation measures and zoning) (Rijkswaterstaat, 2016a). By identifiying the obstacles, measures can be developed, aiming to achieve the conservation goals. Appendix 4 provides an overview of the realization of conservation goals on the short term and the long term. 2.4 Conceptual framework Figure 3 shows the conceptual framework, providing an overview of the concept this research is based on. Using the theoretical framework, the WFD and N2000 goals are recognized, both serving the Eastern Scheldt’s and Lake Grevelingen’s ecology. Furthermore, stakeholders of the research areas are recognized, an overview is provided in Appendix 5. Stakeholders develop projects for their own goals. The priority of water safety remains in the development of the water bodies. For this research, the overlap between project’s goals, WFD goals, N2000 goals and water safety goals forms the basis of the research. Where goals meet (overlap), an opportunity is formed to link projects to the WFD and N2000, adapting the projects into (conservation) measures. The measures contribute to the effort-obligation of the WFD and N2000; moreover the projects receive more (financial) support. Consequently, all goals can be achieved: the sufficient status of the water bodies is achieved within the WFD and N2000 deadlines and the stakeholder’s project is implemented, without deteriorating the water safety.

Figure 3 The conceptual framework.

3. Method This chapter describes the method for acquiring and analysing the results of the research. The results and discussion chapters serve as the answers to the research (sub) question(s) (as described in Chapter 1, paragraph 1.4). First, the research design is described. Secondly, the method for data collection is described. To conclude, the method for the analysis of the results is described. 3.1 Research design The research uses both quantitative and qualitative data, dependent on the research question. Furthermore, a case study is used, in order to fit the scope of the research.

 Quantitative data: For the first sub question focussing at the status of the water bodies, quantitative data is used. The status is dependent on quality elements and conservation goals, which are monitored. The goals and scales used to determine the status are numerical (as shown in Appendix 3 and Appendix 4). In order to conclude if an initiative can serve as an opportunity for the WFD and N2000, the goals and scales are used.  Qualitative data: The overall results will mainly exist of qualitative data. The results of the second sub question are dependent on a descriptive method. The initiatives that could be linked to the WFD and N2000 are dependent on a stakeholder analysis and evaluation of their ambitions and project plans (third sub question). In addition, case comparison is used to evaluate initiatives’ applicability to the research areas. Furthermore, the known effects of the initiatives on water safety are described (fourth sub question).  Case study: Although the research problem involves all water bodies in Zeeland, the Eastern Scheldt and Lake Grevelingen are focussed on, due to the scope of the research.  Scope: The research scope is a time limit. A period of four months is available for the execution of the research. The original problem statement accounts all WFD and N2000 water bodies in Zeeland, however two water bodies were chosen to fit the time limit. 3.2 Data collection For the collection of data, the methods of desk research and consultation are used. 3.2.1 Desk research The theoretical framework is established by desk research, which supports the research results. Publications of monitoring data and the scales and goals set by the WFD and N2000 are used to answer the first sub question. The tables including the goals and scales for the WFD (Appendix 3) and N2000 (Appendix 4) are compared to monitoring data, from which the status of each quality element or conservation goal is concluded. Furthermore, the legal instruments for the WFD and N2000 contribute to answering the second sub question. The method for application of (conservation) measures is derived from the Water Framework Directive, Habitat Directive, Birds Directive and Nature Protection Act. Furthermore, a stakeholder analysis is executed using data from the theoretical framework, which has resulted in a list of stakeholders (Appendix 5). Vision documents and project plans form the basis of the results for the third sub question. Evaluation is done by comparing the ambitions and initiatives’ goals to the WFD and N2000 goals. Evaluation of possible opportunistic measures contributing to the WFD is done via criteria set in the WFD. By analysing the pressures on the research areas in the theoretical framework, suggestion for measures can be collected from studies into the pressures, performed by stakeholders. The most important water safety aspects can be derived from project plans involving the research areas.

3.2.2 Consultation More inclusive information about ambitions and initiatives in development is retrieved via meetings with owners of these initiatives and experts on the different subjects the research includes. During the meetings, questions about the goals and implementation of the initiatives are asked, as well as knowledge about the research areas, ecology, WFD and N2000. Together with the results from the desk research, the initiatives can be assessed as an opportunity or not. The contact persons within stakeholder organisations are supplied by Rijkswaterstaat Zee & Delta. Furthermore, Rijkswaterstaat’s employees are consulted via meetings or e-mail for finding documentations on specific subjects, providing insight on projects and the research areas and for reflection on the research results. The persons consulted are listed in Appendix 8. Furthermore, the questions asked are stated and answers provided by the consultants are translated and summarized. The information is validated by summarizing the relevant discussion points at the end of the meeting, by confirmation through documented sources and providing a summary of the research results to consultants. 3.3 Analysis of results The results of each sub question are analysed. The monitoring results are compared to the scales and goals of the WFD and N2000, from which the status of the water body can be concluded. Furthermore, the goals of stakeholders’ initiatives found in the results are analysed. To conclude, the initiatives’ effects on water safety are assessed. The initiatives found will be assessed as opportunistic or not, by the assessment criteria described below. For N2000, the contribution of the initiative to conservation goals is described. By comparing the status of the water bodies and the goals of different initiatives, links can be recognized. The final results are illustrated in an opportunities-map of the research areas, showing the opportunistic measures contributing to a sufficient status of the Eastern Scheldt and Lake Grevelingen according to the WFD and N2000. To conclude, in the Discussion chapter, the quality of the research is assessed, by questioning the validity of the data collected.

An initiative is considered as an opportunistic measure for the WFD if it meets the following criteria:

1. The initiative contributes to the EQR-score for a (sub) quality element that scores below the GEP (effort-obligation concerning the EQR score); 2. The initiative contributes to the prevention of deterioration of the EQR-score for a (sub) quality element (effort-obligation concerning the prevention of deterioration); 3. The initiative does not deteriorate water safety.

4. Results This chapter provides the results to the research topics described in Chapter 1. Firstly, monitoring data is provided and assessed to the WFD scales and N2000 goals. Secondly, the criteria for the assignment of initiatives as WFD or N2000 measure is described. Thirdly, an overview of ambitions and projects of Rijkswaterstaat and stakeholders at the research areas is provided, describing the initiatives’ goals. The goals are assessed according to the WFD and N2000 criteria. To conclude, the initiatives’ effects on water safety are described. 4.1 Status WFD In order to determine the status of the research areas, monitoring was performed by Rijkswaterstaat (Witteveen+Bos, et al., 2018a). The ‘monitoring results’ are provided and compared to the scales of the WFD. EU Member States are obliged to monitor the (sub) quality elements once every six years (Ohm, Ten Hulscher, & Smits, 2014). However a ‘final result’ is given annually for the status of all quality elements and categories every year, which exists of the mean EQR score of the last three monitoring years. The conclusion of the status per (sub) quality element is made by colour indication, as shown in Table 1. The status of a category (biology, physical chemistry, etc.) is corresponding with the quality element of the lowest score (one-out-all-out principle). The status of the overall ecology and chemistry is corresponding with category of the lowest score. Below, the status per category and quality element is described for 2018. More elaborate information of the method for assessing the status of water bodies according to the WFD is provided in Appendix 6. 4.1.1 Eastern Scheldt Table 3 provides the status of the Eastern Scheldt, concluded from the final results of 2018. Appendix 6 (paragraph A6.1) provides an overview with all results (monitoring and final) of each quality element and corresponding sub quality elements. Below, the overview is summarized and the (sub) quality elements that require improvement are mentioned.

Table 3 The status of the Eastern Scheldt's quality elements according to the WFD goals in 2018. The status was concluded by Rijkswaterstaat (2019a).

Quality element Status 2018 Overall ecology Moderate Biology Moderate Ecology Physical chemistry Good Priority substances Good - Sufficient Overall chemistry Bad – Insufficient Chemistry Ubiquitous substances Bad – Insufficient Non-ubiquitous substances Good – Sufficient Ecology The final result for biology is a moderate status, due to the moderate status of ‘other aquatic flora’ (Rijkswaterstaat, 2019a). The status of ‘other aquatic flora’ is negatively affected by the (measured) absence of Common seagrass and moderate status of seagrass quantity (Rijkswaterstaat, 2019b). The final results for ‘phytoplankton’ and ‘macrofauna’ are good statuses (Rijkswaterstaat, 2019a). The final result for physical chemistry is a good status, due to the good status of all relevant quality elements (Rijkswaterstaat, 2019a). The final result for priority substances is a sufficient status, due to the sufficient status of the relevant substances arsenic and silver (Rijkswaterstaat, 2019a). To conclude, the overall ecology is a moderate status, due to the moderate status of biology.

12 were detected, therefore the non-ubquitous substances are of sufficient status. To conclude, the overall chemistry is of bad status, due to the bad status of the ubiquitous substances. 4.1.2 Lake Grevelingen Table 4 provides the status of Lake Grevelingen, concluded from the final results of 2018. Appendix 6 (paragraph A6.2) provides an overview with all results (monitoring and final) of each quality element and corresponding sub quality elements. Below, the overview is summarized and the (sub) quality elements that require improvement are mentioned.

Table 4 The status of the Lake Grevelingen's quality elements according to the WFD goals in 2018. The status was concluded by Rijkswaterstaat (2019a).

Category Quality element Status 2018 Overall ecology Bad – Insufficient Biology Bad – Insufficient Ecology Physical chemistry Good Priority substances Bad – Insufficient Overall chemistry Bad – Insufficient Chemistry Ubiquitous substances Bad – Insufficient Non-ubiquitous substances Good – Sufficient Ecology The final result for biology is a bad status, due to the bad status of ‘other aquatic flora’ (Rijkswaterstaat, 2019a). The status of ‘other aquatic flora’ is negatively affected by the (measured) absence of seagrass (Rijkswaterstaat, 2019b). The final result for ‘phytoplankton’ is a good status (Rijkswaterstaat, 2019a). The final results for ‘macrofauna’ and ‘fish fauna’ are moderate statuses, and thus require improvement. The latest monitoring result (2016) is a good status, however the AMBI (ratio of sensitive, tolerant and opportunistic species) could be improved (Verduin, Leewis, & Van Haaren, 2018). The sub quality elements of diadromous species and fresh-water species score badly at both quantity and biomass, decreasing the overall status of ‘fish fauna’ (Rijkswaterstaat, 2019b). The final result for physical chemistry is a good status, due to the good status of all relevant quality elements (Rijkswaterstaat, 2019a). The final result for priority substances is a bad status, due to the bad status of the substance arsenic (Rijkswaterstaat, 2019a). The final result for silver is of sufficient status. To conclude, the overall ecology is of bad status, due to the bad status of biology and priority substances.

Chemistry The monitoring result for ubiquitous substances is a bad status, due to the bad status of the substances benzo(ghi)perylene and mercury (Rijkswaterstaat, 2019b). No non-ubiquitous substances were detected, therefore the non-ubquitous substances are of sufficient status. To conclude, the overall chemistry in 2018 is of bad status, due to the bad status of the ubiquitous substances. 4.2 Status N2000 In order to determine the status of the research areas according to the N2000 goals, monitoring was performed, its results shown in the N2000 management plans (Rijkswaterstaat, 2016a). Rijkswaterstaat is responsible for the monitoring and evaluation of the N2000 habitat types and species. The species of water birds and sea mammals are counted by Delta Project Management, as requested by Rijkswaterstaat (Arts, et al., 2018). From the monitoring results, conclusions are made in the management plans. Conclusion on the conservation goals and their status are made every six years (following the cycles of the management plans) (Van Beek, Van Rosmalen, Van Tooren, & Van der Molen, 2014). In Appendix 4, the conservation goals are shown according to the Designation Decree Eastern Scheldt (Minister van Landbouw, Natuur en Voedselkwaliteit, 2009) and Designation Decree Lake Grevelingen (Staatssecretaris van Economische Zaken, 2013). Furthermore, the amount

13 of species monitored is shown, the trend, national conservation status, relative importance and method for conservation is shown according the Management plan (Rijkswaterstaat, 2016b+c). From this information, the realization is concluded per goal. 4.2.1 Eastern Scheldt Below, the goals facing obstacles (or expected to) during the monitoring period (2006 – 2011) of the Management plan Eastern Scheldt 2016-2022 are described. The overview of all habitat types and species and their status (including those with a sufficient status) is provided in Appendix 4 (paragraph A4.1).

Habitat According the Management plan (Rijkswaterstaat, 2016b) the habitat types ‘Transition mires and quaking bogs’, the status is unfavourable, since expansion of the habitat and improvement of its quality is not automatically achieved. Furthermore, the habitat type is facing vegetation succession, which is accelerated due to high nitrogen deposition. The habitat types ‘Large shallow bays’, ‘Salt meadows outside of dikes’, ‘Cordgrass fields’ and ‘Saltwort’, are expected to decrease in the future due to sandhunger (obstacle described in Appendix 1, paragraph A1.1.3). The status of the habitat species ‘Common Seal’ is unfavourable, since the habitat quantity and quality requires improvement (Rijkswaterstaat, 2016b). In addition, the species might be threatened by sandhunger, causing a decrease in potential resting-, moulting- and reproduction area. The status of the ‘Root Vole’ is unfavourable, since the habitat quantity and quality is decreasing. Furthermore, the expansion of habitat is not automatically achieved.

Birds The statuses of coastal breeding birds ‘Common Ringed Plover’, ‘Pied Avocet’ and ‘Kentish Plover’ are unfavourable, due to vegetation succession, predators and insufficient resting (Rijkswaterstaat, 2016b). In addition, new breeding areas do not develop naturally (anymore). In the future, the species will face the consequences of sandhunger. The status of the ‘Little Tern’, ‘Sandwich Tern’ and ‘Common Tern’ is favourable, however future obstacle might by vegetation succession. The goals for the coastal breeding birds are regional goals. This means, the goals and measures account for all N2000 areas in the region ‘Delta Waters’ (Rijkswaterstaat, 2016a). The status for marsh breeding bird ‘Western Marsh Harrier’ is unknown, because the amount of breeding pairs and their trend is unknown (Rijkswaterstaat, 2016b). The statuses of stilt birds ‘Common Ringed Plover’, ‘Dunlin’, ‘Sanderling’, ‘Common Greenshank’, ‘Red Knot’, ‘Pied Avocet’, ‘Bar-tailed Godwit’, ‘Eurasian Oystercatcher’, ‘Ruddy Turnstone’, ‘Common Redshank’, ‘Eurasian Curley’ and ‘Grey Plover’ are favourable, however sandhunger forms a possible obstacle to these species (Rijkswaterstaat, 2016b). The ‘Kentish Plover’ status is unfavourable, and sandhunger might form an obstacle in the future. The statuses of ducks, geese and swans ‘Common Shelduck’, ‘Northern Pintail’, ‘Common Goldeneye’, ‘Eurasian Coot’ and ‘Northern Shoveler’ are unfavourable for unknown reasons (Rijkswaterstaat, 2016b). Sandhunger might form an obstacle in the future. 4.2.2 Lake Grevelingen Below, the goals facing obstacles during the monitoring period (2006 – 2011) of the Management plan Lake Grevelingen 2016-2022 are described. The overview of all habitat types and species and their status (including those with a sufficient status) is provided in Appendix 4: N2000 Conservation goals and status of research areas (paragraph A4.2).

Habitat According the Management plan (Rijkswaterstaat, 2016c), the habitat types ‘Indike salt meadows’, ‘Salt wort’ and ‘Sea pearlwort’ are favourable. However, possible obstacles in the future are

14 desalinisation and vegetation succession due to a lack of dynamics. The status of the habitat species ‘Root Vole’ is unfavourable (Rijkswaterstaat, 2016c). Its habitat’s quality and quantity is decreasing due to forest development and (intensive) grazing. Furthermore, the expansion of the habitat and improvement of the quality of habitat is not automatically achieved.

Birds The statuses of coastal breeding birds ‘Common Ringed Plover’, ‘Pied Avocet’, ‘Kentish Plover’ and ‘Common Tern’ are unfavourable (Rijkswaterstaat, 2016c). The expansion of the habitat and improvement of the quality of habitat is not automatically achieved. Furthermore, the Common Tern is facing predation. The Kentish Plover’s breeding population at the Mediterranean Sea is pressured, which is possibly influencing deltas. The status of the ‘Sandwich Tern’ is favourable, however possible obstacles in the future are predation and lack of suitable breeding locations. The goals for the coastal breeding birds are regional goals. This means, the goals and measures account for all N2000 areas in the region ‘Delta Waters’ (Rijkswaterstaat, 2016a). The status for marsh breeding bird ‘Western Marsh Harrier’ is unfavourable (Rijkswaterstaat, 2016c). The goal is set high and expansion of the habitat is necessary. The statuses of fish-eating birds ‘Great Crested Grebe’ and ‘Horned Grebe’ are unfavourable, however the reason for the unfavourable status is unknown (Rijkswaterstaat, 2016c). Too little fish is expected to be the reason. For the Horned Grebe, there is a small amount of individual birds counted. The status of ducks, geese and swans ‘Common Goldeneye’ is unfavourable, however the cause for the reason for the unfavourable status is unknown (Rijkswaterstaat, 2016c). The low amount of birds is possibly caused by low availability of food (benthos) and the deteriorated water (bed) quality. 4.3 Criteria for assigning measures In order to assign projects as WFD measure or N2000 conservation measure, a process must be followed. In Chapter 2. Theoretical framework, the management of the WFD and N2000 is already described. Below, the process for the application of areas is described according to the WFD and N2000. Furthermore, it is concluded how projects can be linked to the WFD and N2000. 4.3.1 WFD In order to assign a WFD water body, the EU Member States must execute tasks. As described more elaborately in Chapter 2 (paragraph 2.2.1), the Member States’ tasks include the implementation of necessary measures to achieve the GEP of heavily modified water bodies and prevent deterioration of their status within a set time scale (art. 4, WFD, European Parliament and the Council, 2000).

The necessary measures can exist of ‘basic measures’ and ‘supplementary measures’ (art. 11, WFD). Basic measures comply with the minimum requirements to achieve the sufficient status of the water bodies (GEP and no deterioration), accountability of costs by the Member States, prevention of pollution and protection of drinking water sources. Basic measures assure the efficient and sustainable use of water. Supplementary measures can be taken to provide extra protection level of the status of water bodies or to support the basic measures. The combination forms the programme of measures, which is reported in the River Basin Management Plan (RBMP) and send to the EU Commission (art. 15, WFD). Besides the programme of measures, EU Member States are obliged to include the analysis of characteristics, environmental impact assessment of human activities, economic analysis of water use, monitoring programme and assessment of the status of water bodies.

To conclude, an initiative can be included as official WFD measure, by integrating the measure in de programme of measures in the RBMP (Ministerie van Infrastructuur en Milieu, 2015). The WFD coordinator and regional team are responsible for the inventory and assessment of measures (see

15 criteria below) (Van der Schee, 2018). Consequently the request at the national team is made. The responsible regional departments (Rijkswaterstaat Zee & Delta for the research areas) provides an overview of measures, including implementation plan and costs (Poortvliet, 2019). With the assessment criteria, the requested measures are prioritized (Muller, 2019). The available financial means for the WFD measures is an indicator for the implementation of the measures. According the RBMP Scheldt (2015), the planned measures per water body are included in Rijkswaterstaat factsheets (2018). An overview is provided in Appendix 7: Overview of WFD measures.

The National WFD Team’s method to assess if a measure is an opportunity for the WFD uses the following criteria (Van der Schee, 2018):

1. The river basin has an activity that is not realized or difficult to realize. 2. The initiative contributes to the EQR-score for the water body and/or river basin. 3. There is (still) an obligation to take effort at the water body and/or river basin concerning the EQR-score. 4. The initiative is cost-effective.

If criteria 1, 2 or 3 apply and criteria 4 applies, the measure is concerned an opportunity for the WFD (Van der Schee, 2018). Cost-effectiveness is measured by the effort-obligation (concerning EQR-score or prevention of deterioration), effectiveness concerning the improvement of the EQR score and broadened effectiveness by including the N2000 goals (Oterdoom & Muller, 2018). A measure is assessed cost-effective during the prioritising of all submitted WFD measures (Muller, 2019). The cost-effectiveness is assessed by comparing measures to each other, while looking at the available financial means and potential contribution a measure has. For this reason, this report assesses projects only on effort-obligation concerning the EQR and prevention of deterioration, since these criteria are required when submitting a WFD measure. 4.3.2 N2000 As described more elaborately in Chapter 2 (paragraph 2.3.1), Rijkswaterstaat produces management plans for the Delta waters (Rijkswaterstaat, 2016a). The management plans include the status of each goal and the measures that can be taken to maintain, improve or expand the bird and habitat goals. The measures are the result of assessment of the conservation goals. Firstly, measures taken for contribution of other policy framework and programmes (e.g. WFD measures and projects) to the realisation of goals are assessed. If necessary, supplementary measures are planned. Prioritization of measures is done by assessing the trend: goals with a negative trend have priority over goals with a stable or positive trend. The division in tasks for the realisation of measures is already described in Chapter 2. Theoretical framework.

To conclude, an initiative can be included as official N2000 conservation measure, by integrating the measure in the management plans (Rijkswaterstaat, 2016a). Policy framework and projects are assessed to ‘free-ride’ with. Thus, WFD measures are already linked to N2000, by including them in the management plans. Supplementary measures are taken by the responsible regional departments (Rijkswaterstaat, Association Natuurmonumenten, Staatsbosbeheer, Foundation Het Zuid-Hollands Landschap and Foundation Het Zeeuwse Landschap). 4.4 Assessment of initiatives Concluding from the status of the WFD, Rijkswaterstaat is still obliged to realize the WFD goals. Concluding from the N2000 management plans, no additional conservation measures are required to realize the N2000 goals on the short term. For these reasons, the initiatives mentioned in this

16 paragraph contribute to the effort-obligation for the WFD goals. Nevertheless, measures can still contribute to the N2000 goals for which the realization on the long term is uncertain.

In Appendix 7, all current official WFD measures are mentioned. Below, the ambitions and projects (in development) involving the ecology of the Eastern Scheldt and Lake Grevelingen are mentioned. These are potential WFD and N2000 measures. Additionally, projects located elsewhere that could potentially be implemented at the research area are mentioned. A description of the initiatives’ goal is provided. The initiatives’ contribution to the WFD and N2000 goals is assessed. Furthermore, the initiatives’ effects on water safety are described. Consequently, a project is assessed as an ‘opportunistic measure’ or not, using the criteria described in Chapter 3 (paragraph 3.3). 4.4.1 Sand supplementation (Eastern Scheldt) Currently, Rijkwaterstaat is implementing sand supplementations at the Roggeplaat. The Roggeplaat is an intertidal area located in the north-western part of the Eastern Scheldt (see Appendix 1, Figure A2). Sand supplementation is a temporary solution to the process of ‘sandhunger’, which is explained more elaborately in Appendix 1 (paragraph A1.1.3). Sandhunger is causing intertidal areas to become lower and smaller, having negative consequences on nature and water safety (Van Zanten & Adriaanse, 2008). Tidal flats (slikken) and sand banks function as foraging areas for birds and serve as a natural buffer, reducing wave impact on flood defences.

The implementation of sand supplementations for the Eastern Scheldt is included in the Spatial Development Strategy (see Appendix 1, paragraph A1.1.3). The supplementation of the Roggeplaat is included in the N2000 Management plan. The Roggeplaat was chosen due to its rapidly decreasing height and surface (Witteveen+Bos, 2017). The project will contribute to the maintenance goals of ‘Salt wort’, ‘Cordgrass fields’, ‘Salt meadows outside of dikes’ and habitats of ‘Stilts’ (breeding and non-breeding birds), the ‘Common Shelduck’, ‘Northern Pintail’ and ‘Common Seal’ (Witteveen+Bos & Bureau Waardenburg bv, 2013; Rijkswaterstaat, 2016b). According to the Designation Decree Eastern Scheldt, the sand banks and tidal flats, litoral mussel banks and seagrass are part of the maintenance goal of ‘Large shallow bays’ (Minister van Landbouw, Natuur en Voedselkwaliteit, 2009). Witteveen+Bos (2011) mentions the WFD goals for intertidal areas, seagrass and litoral mussel beds, which need to be taken into account when implementing measures. Furthermore, it is stated that benthic fauna and sublittoral communities are not affected by sandhunger, however they will experience disturbance during and short after the supplementation (Witteveen+Bos & Bureau Waardenburg bv, 2013a). By using the method of ‘priming’, in which the sediment layer containing benthos is moved carefully, benthos can recover more quickly from disturbances (Van der Werf, et al., 2016). According to the WFD assessment (see Appendix 6, paragraph A6.1.4), the quality element for ‘macrofauna’ is of good status, meaning there is no effort-obligation to improve the EQR score (Rijkswaterstaat, 2019a).

Erosion of tidal flats located in front of salt marshes (schorren) increases the wave impact on salt marshes and flood defences (Witteveen+Bos & Bureau Waardenburg bv, 2013b). Salt marshes are found adjacent to dikes (see Figure 4), which develop from siltation on tidal flats (Stichting Nationaal Park Oosterschelde, sd). The sediment elevates the tidal flats, allowing vegetation to grow above the water surface. The higher elevated parts of salt marshes only flood during spring tides. The area of salt marshes might decrease, however their quality will not be affected by sand hunger (Witteveen+Bos & Bureau Waardenburg bv, 2013b). Although salt marshes cannot be supplemented due to their vegetation, the supplementation of tidal flats will protect the salt marshes and dikes. The quantity and quality of salt marshes are included in the WFD quality element of (other) aquatic flora (Van der Molen, et al., 2012). The most recent monitoring result (2016) show a moderate score for the quantity of salt marshes, while the quality is of good status. Therefore, sand supplementation

17 of tidal flats located in front of salt marshes contributes indirectly to the aquatic flora goals, which is of moderate status (Rijkswaterstaat, 2019a). Furthermore, the maintenance of salt marshes is a N2000 conservation goal, for which its realisation on the long term is unknown (see Appendix 4, paragraph A4.1).

Figure 4 Locations of salt marsh vegetation at the Eastern Scheldt (Jentink, 2017a).

In the period 1995-2013, the area of salt marshes has decreased from 500 hectares to 465 hectares (Jentink, 2017b). Concluding from trends in salt marsh quality in the period of 2001-2007 can be concluded that climax vegetation or medium high salt marshes have transformed into low salt marshes. In the period of 2007-2013, low salt marshes have transformed into pioneer salt marshes (possible due to a recent cold winter). It is expected that in 2050, salt marshes can only be found in sheltered locations (Rattenkaai and Krabbenkreek) (Van Zanten & Adriaanse, 2008). Consequently, salt marshes will not meet the WFD and N2000 goals. Sandhunger is an autonomous process, therefore the goals are allowed to be adapted. However feasible measures like sand supplementation are still included in the (River Basin) Management Plans. As shown in Figure 4, the Roggeplaat does not protect salt marshes. Therefore, the decision for the second phase of the Spatial Development Strategy determines the opportunities for the WFD and N2000 goals for salt marshes, since only the supplementation of tidal flats located in front of salt marshes contributes to the the protection of salt marshes indirectly. 4.4.2 Hard salt marsh defences (Eastern Scheldt) Salt marshes are minimally affected by sandhunger, since their vegetation holds sediment (Witteveen+Bos & Bureau Waardenburg bv, 2013b). Currently, several salt marshes of the Eastern Scheldt are becoming smaller (Van Zanten & Adriaanse, 2008).

Sea level rise is pressuring the Eastern Scheldt’s salt marshes, causing the areas to ‘drown’ in the future (Witteveen+Bos & Bureau Waardenburg bv, 2013b). Furthermore, many of the Eastern Scheldt’s salt marshes are categorized as ‘old’, meaning the sedimentation has heightened the salt marsh to such an extent that it barely floods (Jacobse, Scholl, & Van de Koppel, 2008). The old salt marshes are eroding. The decrease in intertidal areas due to sandhunger increases the impacts on higher elevated areas. In order to prevent erosion, shoreline defences are most effective at places with a high wave impact, which accounts for all salt marshes at the Eastern Scheldt (Van Zanten & Adriaanse, 2008). A slope made of stone directly at the ‘cliff’ of a salt marsh is able to stop

18 deterioration of the salt marsh (see Figure 5). These hard defences have been applied often and have proven to be an efficient method for the protection of salt marshes. NIOZ is currently researching methods of nature-based (soft) salt marsh defences (NIOZ, 2019). More information about soft defences is found in paragraph 4.4.3.

Figure 5 A slope made of stone directly at the ‘cliff’ of a salt marsh is able to stop loss of the salt marsh (Van Zanten & Adriaanse, 2008).

Tidal flats and salt marshes form a natural buffer for dikes, since intertidal areas decrease the wave impact on dikes (Van Zanten & Adriaanse, 2008). Therefore, the defence of salt marshes serves water safety. Furthermore, the maintenance of salt marshes is a N2000 conservation goal (see Appendix 4, paragraph A4.1). In addition, N2000 habitat goals ‘Cordgrass fields’ and ‘Salt wort’ grow on the wet parts of salt marshes (Witteveen+Bos, 2017). Stilts use salt marshes as habitat during high tides. According to the N2000 Management plan Eastern Scheldt (2016b) and factsheets of the RBMP Scheldt (2018), the implementation of salt marsh defences is already a WFD measure, realized by Rijkswaterstaat during the first cycle of the WFD. The defences contribute to the N2000 conservation goals of coastal breeding birds. The N2000 goals for coastal breeding birds are not achieved or are expected to face obstacles in the future. Furthermore, the maintenance of salt marshes is a N2000 conservation goal, for which its realisation on the long term is unknown due to sand hunger (see Appendix 4, paragraph A4.1). Currently, only few salt marshes contain hard (stone) defence: the salt marshes at the Krabbenkreek, the Rumoirtschor (near Krabbenkreek) and Gouweveer (near Zierikzee), which have proven effective (Jacobse, et al., 2008).

According to the WFD assessment, the final result for ‘other aquatic flora’ is of moderate status (see Appendix 6, paragraph A6.1.4) (Rijkswaterstaat, 2019a). The most recent monitoring result (2016) show a moderate score for the quantity of salt marshes, while the quality is of good status (Rijkswaterstaat, 2019b). Therefore, a measure needs to maintain and ideally expand the area in order to improve the status of ‘other aquatic flora’ (in combination with the improvement of Common seagrass). As mentioned in paragraph 4.4.1, WFD and N2000 goals for salt marshes might need to be adapted if measures prove infeasible to maintain the salt marshes area. 4.4.3 Shellfish reefs (Eastern Scheldt) Besides sand supplementation, the use of shellfish reefs for the protection of tidal flats and sand banks was explored at the Eastern Scheldt (Stichting Ecoshape, 2019a). Oyster and mussel reefs reduce wave impact, which decreases erosion and supports sedimentation (Van Zanten & Adriaanse, 2008). Consequently, the (foraging) area for birds (Red Knot and Eurasian Oystercatcher) and other animals is maintained. Especially mussel banks conserve a high biodiversity that birds can use as food. Oysters occur up to one meter below NAP, while mussels occur up to the water surface, making them suitable for the protection of tidal flats, sand banks and lower parts of salt marshes.

After small-scale pilot experiments in 2009, three large-scale artificial oyster reefs were constructed at the tidal flats of Viane and De Val, as part of the Building with Nature programme (Stichting Ecoshape, 2019b). The Building with Nature programme looks for sustainable solutions for hydraulic engineering problems by using the natural system as starting point (Stichting Ecoshape, 2019c). From the projects, it was concluded that oyster reefs reduce erosion of tidal flats, trap sediment and increase local diversity in a sandy habitat by providing a hard substrate habitat.

Currently, the project More Value with Mussels (Meer waarde met Mosselen) is being executed at the tidal flats of Viane, which researches the possibilities to reintroduce littoral mussel banks at the

Eastern Scheldt and maintain them on the long term at the Eastern Scheldt (HZ University of Applied Sciences, 2014). The involved organisations have different stakes, therefore the research has multiple goals: Create new profitable production locations for the shellfish industry (shellfish growers); Create (alternative) methods to stabilize (the edges) of intertidal areas for sandhunger (Rijkswaterstaat Zee & Delta); Enhance the natural values of intertidal areas and contribute to the N2000 goals (Natuurmonumenten, ARK Natuuronwikkeling and Wereldnatuurfonds). The research project will result in a method for the construction of littoral mussel banks and insight in how the different goals of the involved parties can be joint. Furthermore, the role of mussels as ecosystem engineers and their role in the food web will be researched, as well as the mussels’ capacity to prevent erosion. The HZ University of Applied Sciences is participating with knowledge institutes (NIOZ, IMARES, Deltares), Ecoshape, Province of Zeeland and the mentioned stakeholders.

According to Schug and Wellman (2012), shellfish habitats provide a wide diversity of ecosystem services, as shown in Figure 6. The ecosystem services of ’’Stabilization of submerged land by trapping sediments’’ and ‘’Reduction of marsh shoreline erosion’’ have been used in the experiments (using oysters and mussels) at the Eastern Scheldt. Shellfish reefs attenuate wave energy and reduce erosion of salt marshes and aquatic vegetation. The projects at the Eastern Scheldt were however located on tidal flats, unconnected to salt marshes. Therefore, shellfish reefs could contribute to the WFD sub quality element of areal salt marshes, in case the shellfish reefs are located (on tidal flats) in front of salt marshes. The WFD quality element for ‘other aquatic flora’ is of moderate status, partly by the low quantity of salt marshes, as mentioned before (Rijkswaterstaat, 2019b). Furthermore, shellfish remove suspended solids from water, which increases water clarity (Newell, 2004). This process enables seagrass growth, which is a WFD sub quality element for ‘other aquatic flora’. The final result of 2018 for ‘other aquatic flora’ is of moderate status (see Appendix 6, paragraph A6.1.4) (Rijkswaterstaat, 2019a). The most recent monitoring result (2016) shows a bad status for the total seagrass area at the Eastern Scheldt (Rijkswaterstaat, 2019b). The coverage of Dwarf seagrass is of good status, while no coverage of Common seagrass was detected, resulting in a bad status. Additionally, oyster reefs create habitat for species like benthic interverbrates, crustaceans and fish (Grabowski & Peterson, 2007). A decline in oyster reefs accounts for loss of habitat and decrease in biodiversity (Lotze, et al., 2006). The final WFD result of 2018 for ‘macrofauna’ is of good status (Rijkswaterstaat, 2019a), however the most recent monitoring result (2016) shows an overall moderate status (Rijkswaterstaat, 2019b).

Figure 6 The ecosystem services of shellfish banks (Schug & Wellman, 2012).

According to the N2000 Management plan Eastern Scheldt (2016b), the implementation of oyster reefs on intertidal areas at the Eastern Scheldt is already a WFD measure, realized by Rijkswaterstaat for the first cycle of the WFD. The defences contribute to the N2000 conservation goals of coastal breeding birds. As shown in Appendix 4 (paragraph A4.1), the N2000 goals for coastal breeding birds are not achieved or are expected to face obstacles in the future. Furthermore, the N2000 improvement goal for ‘Large shallow bays’ involves recovery of dry-falling mussel banks (Minister van

Landbouw, Natuur en Voedselkwaliteit, 2009), which the project More Value with Mussels is providing

NIOZ is currently researching methods of ‘soft’ salt marsh defence (NIOZ, 2019). The research involves the study of the island Griend, located in the Wadden Sea. The effectiveness of ecosystem- based water safety is studied, where subsystems (mussel banks, seagrass fields, tidal flats and salt marshes) support each other. More information about the project Griend can be found in paragraph 4.4.11. The outcomes of the research can be used to design a more specific measures involving shellfish reefs. 4.4.4 Seven-island plan (Eastern Scheldt) Foundation Het Zeeuwse Landschap and Delta ProjectManagement have developed the Seven-island plan in assignment of the Province of Zeeland (Castelijns, et al., 2016). From monitoring and a field day (including consultation of experts, managers and protectors of birds), the Province has concluded that breeding areas for coastal breeding birds are pressured. Furthermore, a shortage in suitable breeding areas will arise on the short term. The Seven-island plan contains short-term and long-term measures to assure sufficient breeding areas for coastal breeding birds in and around the Delta waters.

Coastal breeding birds breed in natural dynamic environments, however due to the Delta Works, these dynamics have decreased (Castelijns, et al., 2016). During the construction of the Delta Works and period of large-scale nature development project, the suitable breeding areas remained available, however the current breeding areas become unsuitable due to vegetation succession and presence of predators. According to the Management plan for Delta waters, coastal breeding birds require sufficient breeding areas in order to achieve the conservation goals (Rijkswaterstaat, 2016a). The N2000 conservation goals of coastal breeding birds is a regional goal, since coastal breeding birds choose the most suitable breeding areas in the whole delta annually (Castelijns, et al., 2016).

On the long term, the factors determining the population size of coastal breeding birds are researched (Castelijns, et al., 2016). The research is part of the Life IP Deltanatuur Programme in cooperation with Foundation Het Zeeuwse Landschap and the Province of Zeeland (project Rust voor Vogels, Ruimte voor mensen in de Zuidwestelijke Delta). The project aims for sustainable conservation, which is feasible on the long term. On the short term, measures need to assure sufficient breeding areas, in order to achieve the regional goal of coastal breeding birds. For the construction of breeding areas, the ‘Sandwich Tern’ and ‘Little Tern’ are considered, since they have the highest requirements for breeding areas. Other species can benefit from measures taken for the most critical species.

On the short term, the Seven-island plan provides opportunities for the recovery and maintenance of existing habitat for coastal breeding birds for both the Eastern Scheldt and Lake Grevelingen (Castelijns, et al., 2016). The short-term measures will be included in the nature management activities of the area (Van der Vlugt, 2019). On the longer term, the development of seven islands at the Eastern Scheldt, Western Scheldt and Voordelta is proposed, its locations shown in Figure 7. The locations are already elevated sand banks, that are planned to be heightened using local sediment retrieved from dredging (Castelijns, et al., 2016). The construction of the islands is intended to be executed in phases, since each phase of island development can host its corresponding species of coastal breeding birds. The phase-system fits the pioneer characteristic of coastal breeding birds. The three phases are shown in Figure 8. The project plans will be developed per individual island. Currently, the project plans for the islands in the Western Scheldt are in production, since the situation concerning breeding locations for birds is the most urgent there (Van der Vlugt, 2019).

Furthermore, it is decided that the realization of the Roggeplaat will not be combined with its sand supplementation. The realization of the Katse Plaat is discussed with Association Natuurmonumenten, who owns and manages the sand bank (Van Zijderveld, 2019).

Figure 7 The intended location for the seven islands at the Eastern Scheldt, Western Scheldt and Voordelta. The plan concerns the following locations at the Eastern Scheldt: Dwars in de Weg (4); Katseplaat (5); Roggeplaat (6). (Castelijns, et al., 2016)

Figure 8 The different phases of the development of islands in which different species of coastal breeding birds use the most suitable island as breeding area. Sand banks that rarely flood are most suitable for Little Terns. In the second phase, early stages of dunes suit Sandwich Terns and small seagulls. The last phase involves dunes that suit large seagulls and spoonbills. Since not all island can develop into dunes, the final phase can be replaced with salt marshes, which also suits the breeding area requirements of large seagulls and spoonbills. (Castelijns, et al., 2016)

As shown in Appendix 4 (paragraph A4.1), the N2000 goals ‘Common Ringed Plover’, ‘Pied Avocet’ and ‘Kentish Plover’ are not realized due to vegetation succession, predators and insufficient resting (Rijkswaterstaat, 2016b). Furthermore, the N2000 Management plan states that new breeding areas do not develop naturally (anymore) for these coastal breeding birds. Additionally, the N2000 goals ‘Little Tern’, ‘Sandwich Tern’ and ‘Common Tern’ are expected to meet the obstacle of vegetation succession in the future. The Seven-island plan contributes to realize the goals, since the goals of the plan and the obstacles of the N2000 coastal breeding birds overlap.

According to Van Zijderveld (2019), the realization of the Katseplaat can be combined with aquatic nature around the islands, like seagrass. Furthermore, Het Zeeuwse Landschap pleads for combining management of aquatic nature with nature located above the water surface (Van der Vlugt, 2019). It

22 is suggested to combine the islands with shellfish reefs. Considering the WFD (sub) quality elements and their statuses (improvement is required for areas Common seagrass and areal salt marshes), the implementation of aquatic nature could be combined with the realization of each island at the Eastern Scheldt, since the project plans have not been made yet. To conclude, a project expansion involving aquatic nature could be opportunity to receive more financial means for a project (Poortvliet, 2019). Suggestions for the combination with aquatic nature are made in paragraph and 4.4.11.

The project involves island which are not connected to water defences. As mentioned, it is known that sand banks (first phase(s) of islands) and salt marshes (potential final phase of island) form a natural buffer for dikes, since intertidal areas decrease the wave impact on dikes (Van Zanten & Adriaanse, 2008). Therefore, the islands will contribute to water safety by preventing erosion of the intertidal areas. 4.4.5 Nature compensation (Eastern Scheldt) In the period 2018-2020, the company TenneT realizes a new high-voltage power line between Borssele and Rilland in order to transport sustainably generated wind energy (Zeeuwse Milieu Federatie, 2018). The construction will affect bird habitat. For this reason, Association Natuurmonumenten, Foundation Het Zeeuwse Landschap, Zeeuwse Milieufederatie and TenneT have agreed to compensate for the negative effects on nature by taking measures. Natuurmonumenten will receive financial compensation for the power pylon that will be placed at the Eastern Scheldt near Krabbendijke, which will be used for the mitigation of sandhunger (Van Zijderveld, 2019).

According to Van Zijderveld, the areas near Zandkreek and the port at Neeltje Jans require dredging. Normally, the dredged sediment would be discharged into the deeper channels. However, the sediment can be re-used for mitigation measures. Currently, the type of soil is being researched by NIOZ. If the sediment contains sand, the sediment can be used for the supplementation of the tidal flat Hooghe Kraaijer. If the sediment contains mud (slib), the sediment can be used to develop salt marshes. Both initiatives are located in the South-Eastern part of the south-eastern Scheldt (Kom). The planning is to start dredging in the autumn of 2020. Consequently, the design will be made and permits will be applied for. Stakeholders from the oyster industry will be involved in the process to avoid conflicts. The nature compensation plans are expected to be finished in 2023 (Zeeuwse Milieu Federatie, 2018). If the re-use of dredged sediment proofs successful, the method might be applied again, since more locations require dredging and sand hunger keeps pressuring ecology (Van Zijderveld, 2019). Measures will improve resting- and foraging areas of stilts like the ‘Plover’, ‘Pied Avocet’, ‘Eurasian Oystercatcher’ and ‘Eurasian Curlew’, which are all N2000 goals expected to be pressured by sandhunger (see Appendix 4, paragraph A4.1). If NIOZ’s research results in the creation of salt marshes, the measures contributes to the N2000 goal ‘Salt meadows outside of dikes’, which is currently not realized (see Appendix 4, paragraph A4.4.1) (Rijkswaterstaat, 2016b). Thus, the goals for nature compensation at Kom and the obstacles of N2000 overlap.

Considering the WFD (sub) quality elements and their statuses (improvement is required for areal Common seagrass and areal salt marshes), the implementation of aquatic nature could be combined with the realization of nature compensation. A project expansion involving aquatic nature could be an opportunity to receive more financial means for a project (Poortvliet, 2019). Suggestions for the combination with aquatic nature are made in paragraph 4.4.11. To conclude, if the research concerning the dredged sediment finds mud, the sediment can be used to develop salt marshes. As mentioned, the areal salt marshes is a WFD sub quality element of the quality element ‘other aquatic flora’, which final result in 2018 was of moderate status and thus requires improvement.

The nature compensation measures involve maintenance and protection of intertidal area. As mentioned, it is known that sand banks, tidal flats and salt marshes form a natural buffer for dikes, since intertidal areas decrease the wave impact on dikes (Van Zanten & Adriaanse, 2008). Therefore, the measures will contribute to water safety by maintaining the intertidal areas. 4.4.6 Aquatic nature reserve (Eastern Scheldt) In the Eastern Scheldt Vision 2018-2024, the ambition for an aquatic nature reserve is described, located in the National Park Eastern Scheldt. It is stated that an aquatic nature reserve serves as an supplementary measure to sand supplementation to maintain the quality of nature (Slabbers, Brader, & Sorée, 2018). The National Park includes nature both above and underneath the water surface, including birds, fish, marine mammals and benthos, which support each other within the food chain. The establishment of an aquatic nature reserve will lead to improved protection of species and habitats, improved biodiversity and improved food chain. Furthermore, divers and the fishing industry can benefit from healthy and strong aquatic nature. Additionally, the reserve will contribute positively to nature above the water surface, since it is part of a coherent ecosystem.

In the period 2018-2024, the opportunities for an aquatic nature reserve at the Eastern Scheldt will be researched, involving different sectors (Slabbers, Brader, & Sorée, 2018). The location and size will be researched, as well as different uses. Firstly, it is considered whether the location should be near the water defences or in deeper parts at the South-Eastern part of the Eastern Scheldt (Kom). Secondly, the choice for hard or soft substrate needs to be made. Thirdly, the possibilities for combining the reserve with ‘drowned’ villages, diving locations and fishery sector will be researched. The aquatic nature reserve is envisioned to be established by 2026.

The final result in 2018 for the WFD quality element of ‘other aquatic flora’ is of moderate status (Rijkswaterstaat, 2019a). The latest WFD monitoring results (2016) show a bad status of seagrass, due to the (measured) absence of Common seagrass (see Appendix 6, paragraph A6.1.4) (Rijkswaterstaat, 2019b). At the Eastern Scheldt, Common seagrass only grows at the intertidal area of Oude Tonge (Plaat van Oude Tonge) ( (Jentink, 2017c; IVN Natuureducatie, 2017). However, further development of Common seagrass at this location is pressured by recreation. The final result in 2018 for the WFD quality element of ‘macrofauna’ is of good status (Rijkswaterstaat, 2019a). For N2000, fish-eating birds might profit from the improved habitat for fish. However, the N2000 goals for fish-eating birds are all realized (see Appendix 4, paragraph A4.1) (Rijkswaterstaat, 2016b). 4.4.7 Reintroduction of tide (Lake Grevelingen) Currently, Rijkswaterstaat is planning the project Getij Greveligen (Tides Lake Grevelingen) (Werkverband Grevelingen, 2019). The project objective is to improve the water quality of Lake Grevelingen by reintroducing tidal action via a sluice in the Brouwerdam. The Delta Works caused a lack of hydrodynamics, having negative effects on natural values, like oxygen deficiency. Currently, a sluice in the Brouwersdam (Brouwerssluis) enables permanent exchange of water from the North Sea, which is improving natural processes (Hoeksema, 2002). A sluice in the Grevelingendam (Flakkeese Spuisluis) allows two-way exchange of water with the Eastern Scheldt since 2017 (Werkverband Grevelingen, 2019). The first result on oxygen-level were positive, however the Flakkeese Spuisluis has been closed for the last one and a half years to build a Tidal Test Centre (Poortvliet, 2019). Lake Grevelingen is still suffering from increased absence of oxygen in deep channels, causing benthos to die (Werkverband Grevelingen, 2019). Consequently, essential habitat is lost, resulting in a decrease in biodiversity and economic opportunities. The pressures caused by lack of dynamics are described more elaborately in Appendix 1 (paragraph A1.2.3).

After assessment of scenarios at Lake Grevelingen, the goal is to improve the water quality by reintroducing tides with a tidal range of 50 centimetres at an average water level of -0,20 centimetres NAP (current level) (Ministerie van Infrastructuur en Milieu, 2014). By connecting Lake Grevelingen with the North Sea through a (larger) sluice in the Brouwersdam (Figure 9), oxygen-rich water is supplied and (aquatic) nature can be restored (Rijkswaterstaat, 2019c). The tidal range of 50 centimetres will solve 85 to 90 percent of the problems in oxygen balance (Anon, 2012). By improving the water quality, benthic life (lobsters, crabs, shellfish and worms) is restored. These benthos is the food for birds and fish, creating a robust ecosystem. A robust ecosystem provides opportunities for the (shell)fish industry, recreational sector, a tidal power station and overall quality of life (Werkverband Grevelingen, 2019). The project is a cooperation of Rijkswaterstaat, the provinces of Zeeland and Zuid-Holland, the municipalities of Schouwen-Duiveland and Goeree- Overflakkee and Staatsbosbeheer (Rijkswaterstaat, 2019c). The project is part of the Programmatische Aanpak Grote Wateren (PAGW), in which the government, regional departments and social organisations aim for future-proof large water bodies with high quality nature and a strong economy. The PAGW was established, as WFD and N2000 measures stop when their goals are met, while some large waters require supplementary measures to achieve resilient ecosystems and robust nature (Rijkswaterstaat, 2017).

Figure 9 Artist impression Getij Grevelingen. Via lockable sluice- cylinders seawater flows into Lake Grevelingen during flood and flows out of the lake during ebb. Consequently oxygen-rich water is supplied and water of shallow and deeper parts is mixed. (Rijkswaterstaat, 2019c)

Without action, the WFD goals of ‘macrofauna’, ‘fish fauna’ and ‘other aquatic flora’ are expected to be infeasible by 2035 (Rijkswaterstaat, 2014). Oxygen deficiency (as a result of stratification) of the bottom layer has a negative impact on benthic life in the deeper parts of Lake Grevelingen (Wetsteijn, 2011). The biomass of benthos has been decreasing since 1993 and the composition of benthos has shifted, resulting in an increase in worms in soft substrate macrobenthos. The reintroduction of 50 centimetres tidal range will have a positive effect on the WFD goal for macrofauna (Turlings, et al., 2009). The quality of benthos life will improve due to improved oxygen conditions and the potential development of new intertidal areas around the islands (Hompelvoet, Veermansplaat, Stampersplaat, Dwars in de Weg and the former tidal flats of Bommenede and Slikken van Flakkee) (Dienst Landelijk Gebied, 2014). Tidal flats might develop at the bottom of the intertidal areas, where benthos can locate themselves. The final WFD result for ‘macrofauna’ in 2018 is of moderate status, and thus requires improvement (see Appendix 6, paragraph A6.2.4) (Rijkswaterstaat, 2019a). In the most recent monitoring result (2016), overall macrofauna is of good status, however the AMBI index (measuring sensitivity of species for disturbance) is of moderate status (Verduin, Leewis, & Van Haaren, 2018). For the sub quality elements of ‘fish fauna’, the tidal range will have a positive effect on the amount of estuarine residents and marine species by improving fish migration and oxygen balance (Turlings, et al., 2009; Dienst Landelijk Gebied, 2014). The final WFD result for ‘fish fauna’ in 2018 is of moderate status (Rijkswaterstaat, 2019a). In the latest monitoring results (2017), diadromous species and fresh-water species score insufficiently on both biomass and amount of species (Rijkswaterstaat, 2019b). The amount of species categorized as marine juveniles and marine seasonal quests are of moderate status. Estuarine species score sufficiently. According to the Work Group Grevelingen, the intended tidal range of 50 centimetres will restore 60 to 80 percent of the original oxygen levels at the bottom of the lake, which is

25 sufficient to restore aquatic and benthic life to meet the WFD goals (Werkverband Grevelingen, 2019). Besides ‘macrofauna’ and ‘fish fauna’, the other WFD (sub) quality elements and indicators (see Appendix 3, paragraph A3.2) will not be affected by the tidal range of 50 centimetres (Turlings, et al., 2009). The WFD goal for oxygen balance is of good status, however the indicator only involves surface water (Ohm, Ten Hulscher, & Smits, 2014). The final result in 2018 for the WFD quality element of ‘other aquatic flora’ is of bad status, due to the (measured) absence of seagrass (Rijkswaterstaat, 2019b). For the reintroduction of seagrass, fresh water supply is required, which will not be supplied by the reintroduction of tides (Turlings, et al., 2009). According to Dienst Landelijk Gebied (2014), the realization of tides will increase the salinity in Lake Grevelingen slightly, which decreases the opportunities for seagrass. The reintroduction of seagrass (WFD sub quality element of ‘other aquatic flora’) will only be possible by using more saline-tolerant species (Wetsteijn, 2011). More information about the reintroduction of seagrass at Lake Grevelingen can be found in paragraph 4.4.8.

Tides will change vegetation succession on the shores of islands and banks, resulting in new suitable breeding areas for coastal breeding birds (Turlings, et al., 2009). Additionally, coastal breeding birds can forage on the potentially improved benthos (Turlings, et al., 2009; Dienst Landelijk Gebied, 2014). Therefore, the reintroduction of 50 centimetres tidal range will have a positive effect on the N2000 goals for coastal breeding birds, for which most species score insufficiently (see Appendix 4, paragraph A4.2). Furthermore, the reintroduction of tides has a positive to highly positive effect on fish-eating birds (the fish stock is expected to improve), for which the ‘Great Crested Grebe’ and ‘Horned Grebe’ score insufficiently. Furthermore, the ‘Common Shelduck’ might benefit from tidal action, since the species forage on bottom fauna (Turlings, et al., 2009). For habitat goals, the tidal range has a positive effect on salt marshes, which might result in an increase in birds that use salt marshes as habitat (e.g. ‘Barnacle Goose’, ‘Greylag Goose’, ‘Eurasian Wigeon’ and ‘Eurasian Teal’). ‘Humid dune slacks’ and ‘Fen orchid’ will experience a negative effect (Turlings, et al., 2009; Dienst Landelijk Gebied, 2014). The Netherlands has a great responsibility for these N2000 goals, since Lake Grevelingen is their main habitat (Dienst Landelijk Gebied, 2014). Lake Grevelingen hosts 30 to 50 percent of the national area of ‘Humid dune slacks’ and the ‘Fen Orchid’ is one of the most important species occurring within this habitat type. For these reasons, the negative effect on the habitat types needs to be prevented or limited.

Reintroduction of tidal action will change Lake Grevelingen’s watertype and nature (Ministerie van Infrastructuur en Milieu, 2014). Introducing tides, Lake Grevelingen’s water type will change from M32 (brackish-to-saline lake) to K2 (coastal water that is protected from heavy tidal and wave action, and is part of the polyhaline waters). Consequently, the current WFD and N2000 goals will not apply anymore, thus new goals need to be developed. In order to change the WFD water body type officially, the change needs to be discussed at the RAO and RBO (Van Westen, 2012). Then, the change needs to be motivated in the factsheets (of the RBMP). The manager of the water body is responsible for the adaptation of the WFD goals. For N2000, the goals can be adapted during the development of the (new) Management plan (Minister van Landbouw, Natuur en Voedselkwaliteit, 2009; Staatssecretaris van Economische Zaken, 2013). The new goals have to be included in the River Basin Management Plan Scheldt 2022-2027 and N2000 Management plan Delta Waters and new agreements on financing and execution of management have to be made (Ministerie van Infrastructuur en Milieu, 2014). The changes have to be discussed with the European Union. The national government will change the goals for the WFD and N2000 when the system change is final. The new goals will involve new and different investments, therefore the measures maintaining the current status can be omitted.

According to the Environmental Impact Report (MER), the reintroduction of tides at Lake Grevelingen via the North Sea will not affect water safety (Rijkswaterstaat, 2014). By maintaining the current water level, water barriers and sluices, no additional measures need to be taken concerning water safety.

After the summer of 2019, a decision of preference (MIRT-2 decision) will be made concerning the scope of the project (Werkverband Grevelingen, 2019). The decision involves water level management (mean water level and tidal range), type of sluice and the choice for a tidal energy station. The alternatives have different effects on ambitions, climate robustness, costs (over time), planning, risks and capacity. Furthermore, the project-transcending issues of climate robustness and N2000 are researched. Sea level rise will cause difficulty for the exchange of water from Lake Grevelingen to the North Sea. It is uncertain whether sufficient amounts of oxygen-rich water can be exchanged to support the aquatic nature. Additionally, the effects on N2000 and economics are researched. The partners of the project will advise the Minister of Infrastructure and Water Management and Minister of Agriculture, Nature and Food Quality, who make the decision. After the decision of preference, the plan development phase will start, in which the project-transcending issues are included in an Environmental Impact Report (MER) and the design will be refined. 4.4.8 Reintroduction of seagrass (Lake Grevelingen) Common seagrass was a rather common species in Lake Grevelingen and even expanded after the closure of the lake in 1971 (Nienhuis, et al., 1996). However, the population decreased to 100 hectares in 1993 and disappeared completely a few years later. Reason for the disappearance of seagrass is likely to be the increased salinity, that the seagrass (having low salt-tolerance) could not survive (Giesen, Heusinkveld, & Van Katwijk, 2016). Currently, the circumstances in Lake Grevelingen (natural water management and decreased salinity) form an opportunity for the reintroduction of Common seagrass.

In 2014, a pilot reintroducing Common seagrass was executed at the tidal flats of Flakkee (Slikken van Flakkee). However, the seeds were contaminated with Phytophthora, which reduced germination and thus success of the pilot (Govers, et al., 2015; Giesen, et al., 2016). In order to research the feasibility of the reintroduction of Common seagrass at Lake Grevelingen, another pilot was executed in 2017 (Heusinkveld, Van der Heide, Hoeijmakers, & Govers, 2019). It was concluded that seeds from a donor are able to germinate. Additionally, a new pilot was started in 2018, which will conclude in 2021. In 2018, it was concluded that high densities of lugworms, crabs and microalgae threaten seeds and germs, while crabs, a lack of grazers, algae and low oxygen levels threaten adult plants. In the upcoming period, experiments will be executed to confirm these potential threats as restrictions for the recovery of seagrass. The goal of the project is to achieve recovery of Common seagrass or find the requirements for its recovery at Lake Grevelingen. The locations of the experiments in 2019 are shown in Figure 10.

Globally, seagrass fields are of high ecological and economic importance within coastal zones (Heusinkveld, et al., 2019). Seagrasses act as ecosystem engineers, meaning they alter the abiotic environment of their ecosystem (Van der Heide, et al. in Heusinkveld, et al., 2019; Maxwell, et al., 2016). Firstly, the plants attenuate water movement (Wijgergangs & De Jong, 1999). Calmer waters result in an eutrophic environment for benthic organisms, sedimentation (Wijgergangs & De Jong, 1999) and decreased water turbidity (Van der Heide, et al. in Heusinkveld, et al., 2019). Secondly, the roots of seagrass stabilize sediment, providing coastal protection (Christianen, et al., 2013). Consequently, seagrass supports its own development and provides suitable habitat for species using the plants for foraging, shelter from predators and nursery (Wijgergangs & De Jong, 1999; Maxwell, et al., 2016). Plant-eating birds and macrofauna forage directly on seagrass (Wijgergangs & De Jong,

1999). Other species (e.g. types of snails, crustaceans, echinoderms and fish) forage on the epiphytes growing on the seagrass. Other ecosystem services of seagrass include nutrient cycling (Wijgergangs & De Jong, 1999; Maxwell, et al., 2016) and carbon storage (Mazarrasa, et al., 2015).

Figure 10 The locations for the 2019 experiments at Lake Grevelingen. (Heusinkveld, Van der Heide, Hoeijmakers, & Govers, 2019)

The pilot project is a WFD measure in the second cycle (Rijkswaterstaat, 2018). The project serves the goal for the improvement of ‘other aquatic flora’. In 2018, the final result for the WFD quality element of ‘other aquatic flora’ was of bad status (Rijkswaterstaat, 2019a). The most recent monitoring results (2013 and 2017) both show an overall bad status of ‘other aquatic flora’ (see Appendix 6, paragraph A6.2.4) (Rijkswaterstaat, 2019b). The sub quality elements ‘seagrass quantity’ and ‘seagrass quality’ are both of bad status according to the monitoring results. Specific fish species use seagrass as a nursery (Kikuchi, in Wijgergangs & De Jong, 1999). Furthermore, fish use seagrass as a shelter from predators (Sogard & Olla, 1993). At Lake Grevelingen, fish fauna (e.g. Grobies, Three-spined sticklebacks, Herrings and Sand smelts) had the opportunity to expand during the period of increasing seagrass areal (Doornbos, in Wijgergangs & De Jong, 1999). As mentioned in paragraph 4.4.7, the final WFD result for ‘fish fauna’ in 2018 is of moderate status, and thus requires improvement (Rijkswaterstaat, 2019a). The final result in 2018 for the WFD quality element ‘macrofauna’ is of moderate status (Rijkswaterstaat, 2019a). The latest monitoring result (2016) shows a good overall status for ‘macrofauna’ (Verduin, et al., 2018). The latest monitoring result (2016) for the sub quality element AMBI index (measuring sensitivity of species for disturbance) is of moderate status. It is researched that the species richness and density of macrofauna (mostly epifauna: species of hard substrate) are higher at locations with seagrass than at locations without seagrass (Orth, Heck, & Van Montfrans, 1984; Boström & Bonsdorff, 1997). Escaravage & Hummel (2004) confirm this relation between macrofauna and seagrass for Lake Grevelingen specifically. According to Boström & Bonsdorff (1997), seagrass has a positive effect on macrofauna, due to seagrass’ following characteristics:

 Low predation due to the complexity of the habitat;  Active habitat choice by organisms looking for shelter from predators or currents;  Accumulation of nutritious particles and substrate used for epiphytic production.

The occurrence of Common Seagrass at Lake Grevelingen mainly determines the presence of plant- eating birds (Holland, 1991). Figure 11 shows the correlation between the decrease of plant-eating birds and the decrease of seagrass area (De Kraker, in Wijgergangs & De Jong, 1999). Especially the N2000 species Eurasian Wigeon, Mallard, Eurasian Teal and Eurasian Coot are negatively affected by the decrease of seagrass, since they forage on the seagrass. The N2000 species Brant goose also forages on seagrass, however can forage on alternative food sources. The mentioned N2000 goals

28 are all realized and are expected to remain of sufficient status on the long term (see Appendix 4, paragraph A4.2) (Rijkswaterstaat, 2016c). As mentioned, fish fauna had the opportunity to expand during the period of increasing seagrass area (Doornbos, in Wijgersgangs & De Jong, 1999). The characteristic fish species (Grobies, Three-spined stickleback, Herring and Sand smelt) for seagrass habitats in shallow parts of Lake Grevelingen form food source for fish-eating birds (Holland, 1991). The N2000 goals for the fish-eating birds the ‘Horned Grebe’ and ‘Great Crested Grebe’ are currently not realized (see Appendix 4, paragraph A4.2) (Rijkswaterstaat, 2016c). Although the obstacle is unknown, the species are expected to have too little fish.

Figure 11 The correlation between the occurrence of seagrass (bars) in Lake Grevelingen and the amount of herbivore birds (line). Occurrence of seagrass is measured from a coverage of more than five percent of seagrass coverage. (De Kraker, in Wijgergangs & De Jong, 1999)

Figure 12 shows a map with the opportunistic locations for the development of Common seagrass at Lake Grevelingen. Depths of one to three meters are considered as highly opportunistic location for the development of seagrass (De Jong, 2017).

Figure 12 Map with opportunities for development of Common seagrass based on the different depths and previous occurrence of Common seagrass in 1994 in Lake Grevelingen. Depths of 1 to 3 meters are considered as highly opportunistic (dark green). Depths of 0,1 to 1 meter and 3 to 4 meters are considered opportunistic (light green). (De Jong, 2017)

4.4.9 Bird islands (Lake Grevelingen) In the period August 2018 until December 2018, Staatsbosbeheer implemented new bird islands at Lake Grevelingen (Staatsbosbeheer, sd). The islands are located at the existing islands Markenje, Kleine Stampersplaat and Kabbelaarsbank (see Figure 13), which were chosen after assessment of eight potential locations (Ter Harmsel, Van Boheemen-Gerritsen, & Puts, 2016). The Lake’s scarcely vegetated banks, accessible foraging habitat, richness in fish and nutrient-rich in dike meadows create a suitable areas for coastal breeding birds. Shellfish islands were constructed to serve as

29 breeding areas, in order to contribute to the N2000 conservation goals for the ‘Pied Avocet’, ‘Common Tern’, ‘Common Ringed Plover’, ‘Kentish Plover’, ‘Sandwich Tern’ and ‘Little Tern’ (Staatsbosbeheer, sd). Shellfish islands have become scarcer at Lake Grevelingen after the construction of the Brouwersdam. The project is not included in Lake Grevelingen’s N2000 Management plan 2016-2022 (Rijkswaterstaat, 2016c). The upcoming years, the Life IP Deltanatuur programme will monitor the effects of the bird islands concerning the settlement and breeding of coastal breeding birds (RPS, 2018). The information can be used to for future organisation of bird islands.

Figure 13 The locations of preference for the construction of bird islands. (Ter Harmsel, et al., 2016)

The project contributes to the N2000 goals for coastal breeding birds. The goals for the ‘Sandwich Tern’ is possibly pressured by the lack of suitable breeding areas (see Appendix 4, paragraph A4.2) (Rijkswaterstaat, 2016c). The other goals for the mentioned species (except for the ‘Little Tern’) are currently not realized. Furthermore, the project could be combined with aquatic nature, in order to contribute to the WFD goals (Poortvliet, 2019). Suggestions for the combination with aquatic nature are made in paragraph and 4.4.11. 4.4.10 Waddenmozaïek Association Natuurmonumenten, University of Groningen and NIOZ have initiated the project Waddenmozaïek (Wadden mosaics) at the Dutch Wadden Sea, as part of the Waddentools programme (Govers, Van der Heide, Olff, & Smeele, 2018). The goal of the Waddentools programme is to create a toolbox including tested measures that aims for a ‘rich’ and optimal functioning Wadden Sea. In a rich Wadden Sea, the foodweb is complete, containing healthy fish stock and extensive shellfish banks, providing nursery, resources and breeding area. Despite of the Wadden Sea’s protection status, the water body is pressured by human activities, like shell extraction, dredging and fishing (at the waterbed). The project Waddenmozaïek focusses on recovery measures of the Wadden Sea’s waterbed, existing of sand, sludge, rocks, mussel banks, seagrass fields and oysters, together forming a diverse ‘mosaic’. The project will experiment with measures aiming for the recovery of aquatic nature via five subprojects. Besides the mentioned initiators, Staatsbosbeheer, Rijkswaterstaat and Coalitie Wadden Natuurlijk are involved in the project. Below, the subprojects’ questions planned to be answered by executing experiments (in the period 2019- 2020) are described.

Subproject 1 questions the effect of closing an area from waterbed-fishing (e.g. mussels, shrimps, fish by-catch) on the recovery of ecosystem engineers and the food web (Govers, et al., 2018). The experiments will result in a management advice concerning the closure of waterbed-fishing areas, its scale and expected recovery time. Subproject 2 questions the contribution of hard substrates to the

30 quality of aquatic nature, which will result in an advice concerning the construction of hard substrates (gravel, rocks and shellfish) that benefit a rich Wadden Sea. Benefits could possible include the settlement of species like mussels, oysters, macro-algae and sponges. Subproject 3 questions which possible recovery measures there are for the recovery of permanently flooded shellfish banks. Experiments will provide insight in the possibilities for the recovery of permanently flooded shellfish banks, since shellfish provide ecosystem services (see paragraph 4.4.3). Subproject 4 questions which recovery measures there are for the recovery of permanently flooded seagrass. Experiments will result in a map with opportunistic locations for seagrass recovery and insight in key factors for seagrass recovery, since seagrass provides ecosystem services (see paragraph 4.4.8). Subproject 5 will map the current nature (habitats and the food web) of the (permanently flooded parts of the) Wadden Sea, in order to support recovery measures. The project will result in habitat- map and a map with opportunities for nature, visualization of the food web, management instructions and an advice about suitable monitoring methods.

The results of the subprojects at the Wadden Sea are relevant for the mentioned initiatives at the Eastern Scheldt and Lake Grevelingen, since they could be applied at the research areas, serving the WFD and N2000 goals (Poortvliet, 2019). The Wadden Sea is categorized as WFD watertype K2, just like the Eastern Scheldt (Van der Molen, et al., 2012). Lake Grevelingen’s watertype will change from M32 to K2, once tides are reintroduced (see paragraph 4.4.7) (Ministerie van Infrastructuur en Milieu, 2014). Subproject 1 corresponds with the ambition for an aquatic nature reserve at the Eastern Scheldt (see paragraph 4.4.6), since both projects question the effects of the (lack of) use to support aquatic nature. Subproject 2 and 3 corresponds with the initiative concerning shellfish reefs at the Eastern Scheldt (see paragraph 4.4.3), since both initiatives aim for the ecosystem services shellfish reefs provide. Subproject 4 corresponds with the pilot project (and WFD measure) focussing on the recovery of seagrass (see paragraph 4.4.8), since both initiatives aim for to benefit from the ecosystem services seagrass provides. The WFD and N2000 goals the initiatives serve can be found in the paragraphs referred to. 4.4.11 Island Griend The uninhabited island Griend, located in the Wadden Sea, is threatened to disappear due to erosion (Govers, Van der Heide, Olff, Smeele, & Van der Eijk, 2017). The manager of Griend, Association Natuurmonumenten, wants to conserve the island, for its high natural importance. The island serves as breeding, resting and foraging habitat and high-tide refuge for large amounts of birds, as well as habitat for seals. Furthermore, the tidal flats around Griend (Grienderwaard region), conserve high benthic biomass and birds (species typical for Wadden Sea’s intertidal zones). Before the construction of the Afsluitdijk, Griend used to ‘walk’ (move) in southeast direction due balanced erosion and sedimentation on opposite sides of the island. After the construction of the Afsluitdijk (1932), the tidal range increased. Consequently, erosion increased and the island became smaller. Multiple measures were taken to conserve the island, however they were ineffective on the long term.

In August and September of 2016, recovery measures started, aiming to protect the island from rapid erosion and allow the island to flood more frequently (Govers, et al., 2017). Sand supplementations, placement of shellfish piles, the lowering of a sand dike and removing vegetation serve as temporary measures, providing time to improve the understanding of the Griend system. In 2016 a multi-year research into processes that support and keep balanced the ‘walking’ of islands like Griend started. The subsystems mussels, seagrass fields, sand spit (schoorwal), salt marshes and sand banks are all expected to support sedimentation and slow down erosion, as shown in Figure 14. Currently, the ecosystem engineers mussel banks and seagrass are missing, resulting in a lack of natural support of

31 the sand spit. The ecosystem services of mussel banks and Common seagrass are described in paragraphs 4.4.3 and 4.4.8. In the spring of 2017, experiments started to investigate the relation between mussel banks, seagrass fields and Griend’s ‘walking’. Biodegradable constructions (mosselkratten), that have proven to stimulate mussel growth on different location in the Wadden Sea, were placed on two locations at Griend. Common seagrass was sowed just behind the constructions for mussels. In order to gain insight in the effects of the 2016 recovery measures and the experiments involving mussels and seagrass, Griend and its surroundings are extensively monitored until the end of 2019. The monitoring will result in insight in Griend’s geomorphological developments. Furthermore, the experiments will result in insight in the settlement and effects of mussels and Common seagrass. The scope of the experiments is too small to recover Griend, however the results can be used to take suitable (management) measures in the future.

Figure 14 The subsystems allowing Griend to ‘walk’ by supporting each other. Mussel banks break waves for seagrass, dead shells, plants feed the sands pit, the sand spit protect the salt marsh and the salt marsh traps clay. If one or more subsystem is pressures or removed, the whole system is affected. (Janne Nauta in Govers, et al., 2017)

The results of the experiments at Griend are relevant for the different initiatives at the Eastern Scheldt and Lake Grevelingen, since they could be applied at the research areas, serving the WFD and N2000 goals (Poortvliet, 2019). The Wadden Sea’s correspondence with the water types of the research areas is described in paragraph 4.4.10. Mussel banks and their effects on the ecosystem services are currently researched in the Eastern Scheldt in the project More Value with Mussels (see paragraph 4.4.3) (HZ University of Applied Sciences, 2014). Furthermore, the reintroduction of Common seagrass is currently researched in Lake Grevelingen (see paragraph 4.4.8) (Heusinkveld, et al., 2019). In the Eastern Scheldt, Foundation Het Zeeuwse Landschap has the ambition to implement (part of) the Seven-island plan (see paragraph 4.4.4) (Castelijns, et al., 2016). The creation of the islands for coastal breeding birds could be combined with mussel banks and seagrass fields, whose ecosystem services support the maintenance of the islands (similar to Griend) and the WFD and N2000 goals (see paragraph 4.4.3 and 4.4.8). Furthermore, Association Natuurmonumenten might support the development of salt marshes at the south-eastern part of the Eastern Scheldt, dependent on the sediment available (see paragraph 4.4.5) (Van Zijderveld, 2019). The implementations of the subsystems mussel banks and seagrass fields can support the maintenance of the salt marshes (similar to Griend) and support the WFD and N2000 goals. For Lake Grevelingen, the opportunistic location for the reintroduction of seagrass (see Figure 12), overlap with the locations were bird islands were recently constructed (see paragraph 4.4.9 and Figure 13). Seagrass’ ecosystem services (see paragraph 4.4.8) could contribute to the maintenance of the islands, serving WFD and N2000 goals. To conclude, the outcomes of the research of Griend can be used to expand initiatives at the research areas and serve WFD and N2000 goals more extensively.

5. Discussion In this chapter, the quality of the research results is discussed. The interpretation, validity and limitations of the results are discussed. Furthermore, possible differences between theory and practise are described. The chapter is divided in subjects that raise questions concerning the quality of the research. 5.1 WFD The status of the WFD quality elements per water body is concluded annually, however EU Member States are obliged to monitor once every six years (Ohm, et al., 2014). The ‘final result’, which is concluded annually, exists of the mean score of the last three monitoring years. For this reason, a ‘final result’ of a particular year can differ from the ‘monitoring result’ of that same year. This makes assessing the status and contribution of initiatives to the EQR-score more complex, since the relevance of the results differ. Furthermore, monitoring of all (sub) quality elements is not performed simultaniously (in the research areas) (Rijkswaterstaat, 2019b), which complicates the comparison of (sub) quality elements. In addition, the one-out-all-out-principle might provide an unrealistic status of a water body, since the water body can be assessed of bad status, while only one (sub) quality element might be of insufficient status.

Lake Grevelingen is classified as the WFD water type M32, which is a brackish-to-saline lake (Rijkswaterstaat, 2018). Part of the WFD quality element ‘fish fauna’ is the quantity and biomass of fresh-water species with a chloride-tolerance of equal or less than 8 grams per liter (type Z1) and equal or less than 4 grams per liter (type Z2) (Van der Molen, et al., 2012). However, Lake Grevelingen is known to be Europe’s largest saltwater lake (Rijkswaterstaat, 2014; Tangelder, et al., 2018). The lake’s aimed salinity is 16 grams chloride per liter (Wetsteijn, 2011). Questions can be raised for the motive of including fresh-water species to measure the ecolgical status of a salt water body.

The WFD quality element ‘macrofauna’ is determined by using the BEQI2-method, which exists of the sub quality elements Species richness, Shannon index and AMBI (Van der Molen, et al., 2012). For species richness, the amount of species are counted in a sample area (Van Loon, et al., 2015). The Shannon Index measures the abundance of species and the AMBI measures the sensitivity of species for disturbance by using the Borja formula. The EQR-score for each sub quality element is calculated by using the reference (the maximum score), which mean forms the BEQI2-score or overall ‘macrofauna’ monitoring result. When taking measures to improve or maintain the status of WFD quality element ‘macrofauna’, the measure needs to contribute to these three sub quality elements. However in practise, measures focus on the creation of habitat and suitable circumstances of specific species. In order to conclude if an initiative contributes to the EQR-score of ‘macrofauna’, the status per species would be required. However the BEQI2-method and lack of clear overview of monitoring results and calculations complicates the possibility to conclude wat the contribution of initiatives to macrofauna is. Therefore, the contributions of the described measures in the research results are based on documented sources about the contribution to the overall status of macrofauna. The quality of the research results (involving the assessment of initiatives) could have been higher if the sub quality elements could have been used to assess the effects of initiatives on them.

Currently, 90 percent of the WFD measures from the first cycle are not maintained (Van Schijndel & Van Es, 2019). The contribution to the ecological water quality of measures that are maintained is questioned. This statistics are considered unacceptable, considering the large scope of the European WFD programme. The WFD is not responsible for management of measures taken, however in order to achieve the aimed results of a measure, sufficient transfer of measures to maintenance and

33 management organisations is required. According to Van Schijndel & Van Es, management needs to be included on the short term in order to improve the WFD implementation programme. The lack of management after the implementation of measures affects the research, since management of measures enhances the effectiveness of measures. Additional measures, which involve additional costs, might not be necessary when proper management of measures was included in an earlier stage. 5.2 N2000 The assessment of the realization of the N2000 goals in the most recent management plans (2016) is based on monitoring data from the period 2006/2007 until 2010/2011 (Rijkswaterstaat, 2016b+c). The management plans are valid until 2022. Yet, monitoring of water birds and sea mammals is done monthly (Arts, et al., 2018). The use of old monitoring data to conclude the status of the N2000 goals possibly decreases the quality of the research, in case the statistics have changed considerably. The status of the N2000 goals per water body are old, and since the last countings on which the goals are based, birds and trends might have changed over time. Consequently, the assessment of the contribution of initiatives to the realization of the N2000 goals is of low accuracy. Therefore, the motivation for each initiative as opportunstic is less strong than with more recent results of the realization of N2000 goals. 5.3 Assessment of initiatives The scope of the effect of sandhunger on the decrease of salt marshes in the Eastern Scheldt is unclear. Witteveen+Bos & Bureau Waardenburg bv (2013b) state that salt marshes are minimally affected by sandhunger, since their vegetation holds sediment. Furthermore they state that erosion (due to sandhunger) of tidal flats in front of salt marshes increases the wave impact on salt marshes. Additionally, sea level rise is causing the salt marshes at the Eastern Scheldt to drown in the future. Moreover, it is expected that salt marshes can only be found in sheltered locations by 2050 (Van Zanten & Adriaanse, 2008). It is questioned whether the WFD and N2000 goals should be adapted due to the autonomous process of sandhunger. The reasons provided for the decrease in salt marshes are controversial, since it is stated that salt marshes are minimally affected by sandhunger, yet their goals might not be met due to sandhunger. This contradiction affects the quality of the motivation for the contribution of initiatives to the WFD and N2000 goals, because the effectiveness of the initiative depends on the highest pressure it is tackling, which is either sandhunger or sea level rise.

The reintroduction of tides in Lake Grevelingen will restore the aquatic and benthic life sufficiently to meet the WFD goals (‘macrofauna’ and ‘fish fauna’) (Werkverband Grevelingen, 2019). The other WFD (sub) quality elements and indicators will not be affected by the intended tidal range of 50 centimetres (Turlings, et al., 2009). However, according to Dienst Landelijk Gebied (2014), the realization of tides will increase the salinity in Lake Grevelingen slightly, which might decrease the opportunities for seagrass. The reintroduction of seagrass (WFD sub quality element of ‘other aquatic flora’) will only be possible by using more saline-tolerant species (Wetsteijn, 2011). Thus, the effects of tides on ‘other’ WFD quality elements are controversial. Furthermore, reintroduction of tides will require a shift in the nature and water type and thus in the water type and because of that the WFD and N2000 goals have to be adjusted (Ministerie van Infrastructuur en Milieu, 2014). It is stated that the different goals will involve different investments, therefore the measures maintaining the current status can be omitted at a point where the project will be implemented on the short term. This statement questions the motive for each WFD and N2000 measure taken or planned at Lake Grevelingen, since their effects might not be relevant anymore after the implementation of the project Getij Grevelingen. For example, measures taken to improve the status of the WFD quality

34 element ‘fish fauna’ might not apply, since the water type K2 does not include the quality element ‘fish fauna’. On the other hand can the support of fish fauna contribute to the N2000 goals of ‘fish- eating birds’.

To conclude, the significance of the measures can be questioned. Initiatives might meet the criteria set in Chapter 3, however their contribution to the EQR-score or amount of birds or trends is not quantified in the assessment of the initiatives. The motivation for the contribution to the EQR-score or N2000 goals could be stronger if the initiatives’ contribution would be quantified. Deltares has developed the KRW-verkenner; a software tool for the calculation of the effects of (potential) measures on the ecological status for the WFD (Deltares, sd). Using this tool would require new quantified criteria for the assessment of initiatives as opportunistic or not. A different method would be to determine significance by setting criteria for the surface an initiative requires compared to the water body’s surface. The quantification of the contribution of initiatives to the WFD and N2000 is beyond the scope of this research. Finally, the initiatives’ effects on external activities at the research areas, like the (shell)fish industry and recreation, are beyond the scope of this research, since only the potential effects for the WFD and N2000 goals are part of the research’s problem definition.

6. Conclusion & Recommendations Following from the research results, the research question can be answered. Below, the sub questions are answered first. Then, the main question is answered using the research’s product: a map with opportunistic measures serving the goals of the WFD and N2000 at the research area. 6.1 Sub questions 1. What is the current status of the Eastern Scheldt and Lake Grevelingen according to the goals of the WFD and N2000? According to the WFD goals, the overall ecology of the Eastern Scheldt in 2018 has a moderate status, due to the moderate status of the water body’s biology. Furthermore, the Eastern Scheldt’s overall chemistry has a bad status, due to the bad status of ubiquitous substances. The overall ecology of Lake Grevelingen has a bad status, due to the bad status of the water body’s biology and priority substances. Furthermore, Lake Grevelingen’s overall chemistry has a bad status, due to the bad status of ubiquitous substances.

According to the N2000 goals, the Eastern Scheldt’s goals for habitat types and habitat species, coastal breeding birds and ducks, geese and swans are not realized. Stilts might not be realized in the future. Lake Grevelingen’s goals for habitat species, coastal breeding birds, marsh breeding birds, fish-eating birds and ducks, geese and swans are not met. Habitat types might not be realized in the future.

2. What are the criteria for the WFD and N2000 and how can they be linked to independent projects? An initiative is considered an opportunity for the implementation of the WFD if the initiative includes the effort-obligation to achieve the goal (GEP) and the prevention of deterioration of the status of the water body’s goal(s). The initiative is officially linked to the WFD, if the initiative is included in the WFD River Basin Management Plan. An initiative is considered opportunistic for the implementation of N2000 if the initiative contributes to the goals set in the Designation Decree for a N2000 area. The initiative is officially linked to N2000, if the initiative is included in the N2000 Management plan.

3a. What initiatives are in development that could be linked to the goals of the WFD & N2000 at the Eastern Scheldt by Rijkswaterstaat and other stakeholders? The sand supplementations of the Roggeplaat do not contribute to the protection of salt marshes. A decision on other supplementations has not been made yet. Sand supplementation of tidal flats located in front of salt marshes is an opportunity for the implementation in the third cycle of the WFD and N2000, because:

 The measure includes the effort-obligation concerning the prevention of deterioration of the WFD quality element ‘other aquatic flora’;  The measure contributes to the N2000 goals of ‘Salt meadows outside of dikes’, ‘Cordgrass fields’, ‘Stilts’, ‘Common Shelduck’, ‘Northern Pintail’ and the ‘Common Seal’.

Hard defences of salt marshes maintain the amount of area, however none are currently planned to be constructed. The measure of hard defences is an opportunity for the implementation of the third cycle of the WFD and N2000, because:

 Only few salt marshes contain hard defences (Krabbenkreek, Rumoirtschor and Gouweveer).  The measure includes the effort-obligation concerning the prevention of deterioration of the WFD quality element ‘other aquatic flora’;

 The measure contributes to the N2000 goal of ‘Salt meadows outside of dikes’, ‘Saltwort’, ‘Cordgrass fields’, ‘Stilts’ and coastal breeding birds.

The project ‘More Value with mussels’ is being executed at the tidal flats of Viane, however not located in front of salt marshes. The implementation of shellfish reefs is an opportunity for the implementation of the third cycle of the WFD and N2000, because:

 The measure includes the effort-obligation concerning the EQR-score and prevention of degradation of the WFD ‘other aquatic flora’, on condition that the intertidal area stabilized with shellfish is located in front of a salt marsh;  The measure includes the effort-obligation concerning the prevention of degradation of WFD quality element ‘macrofauna’;  The measure contributes to the N2000 goal of ‘Salt meadows outside of dikes’, ‘Large shallow bays’ and coastal breeding birds.

The implementation of the seven-island plan is an opportunity for N2000, because the measure contributes to the N2000 goals of coastal breeding birds. Furthermore, combinations with aquatic nature could be made, similar to the island Griend, which can serve the WFD goals for ‘other aquatic flora’ and ‘macrofauna’.

The implementation of the nature compensation, at either the Hooghe Kraaijer or elsewhere in the Kom, is an opportunity for the realization of the N2000 goals, because the initiative contributes to the N2000 goals for habitat and stilts. Furthermore, the creation of salt marshes (as part of nature compensation) is an opportunistic measure for the WFD, since the measure includes the effort- obligation concerning the prevention of deterioration of the WFD quality element ‘other aquatic flora’.

The aquatic nature reserve could be an opportunity for the WFD, dependent on the location. If a location with (reintroduced) Common seagrass is chosen, the reserve contributes to the EQR-score of ‘other aquatic flora’. The protection of macrofauna contributes to the prevention of the deterioration of the WFD quality element ‘macrofauna’.

3b. What initiatives are in development that could be linked to the goals of the WFD & N2000 at Lake Grevelingen by Rijkswaterstaat and other stakeholders?

The reintroduction of tides at Lake Grevelingen will contribute to the effort-obligation for the EQR- scores of ‘macrofauna’ and ‘fish fauna’. Furthermore, the project affects different N2000 goals both positively and negatively. Therefore, the project is an opportunity for the WFD. However, the goals for both the WFD and N2000 might change, therefore the status according to the WFD and N2000 is unknown after the implementation of the project. Yet, the project is expected to serve the WFD goals. Measures for the compensation and mitigation of negative effects on N2000 goals are being researched, which outcomes can be used to assess the project as an opportunity for N2000.

The results of the pilot projects can be used (to set the criteria) for the reintroduction of Common seagrass at Lake Grevelingen. The map with opportunistic locations for the reintroduction of seagrass can be used (Figure 12). The reintroduction of seagrass is an opportunity for the implementation of the third cycle of the WFD and N2000 because:

 The measure includes the effort-obligation concerning the EQR-scores of the WFD quality elements ‘other aquatic flora’, ‘macrofauna’ and ‘fish fauna’;  The measure contributes to the N2000 goals for fish-eating birds.

The bird islands created for coastal breeding birds serve the N2000 goals. Furthermore, the combination with aquatic nature could be made, similar to the island Griend, which can serve the WFD goals for ‘other aquatic flora’, ‘macrofauna’ and ‘fish fauna’.

4. Will the initiatives deteriorate water safety? The defence of salt marshes through sand supplementations of tidal flats, hard defences and shellfish reefs contribute to water safety at the Eastern Scheldt. Furthermore, the creation of islands (seven- island plan) and intertidal areas (nature compensation) contribute the Eastern Scheldt’s water safety. The designation of an aquatic nature serve at the Eastern Scheldt does not affect water safety.

The reintroduction of tides at Lake Grevelingen will not affect water safety. The reintroduction of Common seagrass contributes to Lake Grevelingen’s water safety due to seagrass’ ability to stabilize sediment.

The combination of aquatic nature with islands or intertidal areas (seven-island plan at the Eastern Scheldt and bird islands at Lake Grevelingen) contributes to water safety. 6.2 Research question The sub questions together answer the main research question:

Which opportunities can serve the goals of the Water Framework Directive and Natura 2000 in the Eastern Scheldt and Lake Grevelingen while not deteriorating water safety?

The complete overview of opportunistic initiatives at the Eastern Scheldt and Lake Grevelingen according to the assessment of initiatives is shown in the opportunities-map in Figure 15. Furthermore, locations for potential measures are shown on the map: opportunistic location for the reintroduction of seagrass; tidal flats (located in front of salt marshes) that can be defended by shellfish reefs or sand supplementations; salt marshes that can be defended by hard or soft defences; islands that can be protected by subsystems supporting each other.

Figure 15 The opportunities-map for the Eastern Scheldt and Lake Grevelingen. The map includes opportunistic initiatives and potential measures that could be implemented to serve the WFD and N2000 goals. The map is available on A0 in Appendix 9.

The opportunities-map forms a vision for the Eastern Scheldt and Lake Grevelingen, resulting from the research. All initiatives and potential measures included in the map contribute to the implementation of the WFD and N2000 at the research areas. The different stakeholders of research areas’ ecology are included in the map. The combination of the participation of stakeholders and implementation of the opportunistic initiatives as WFD and N2000 measures contributes to the integral vision:

Concerning the WFD, N2000 and stakeholders, it is recommended to:

 Use the WFD and N2000 as coherent programmes instead of two separate tasks, in order to serve a broader goal and achieve more by taking measures that serve both the WFD and N2000 goals. Specifically, there are relations between WFD’s ‘other aquatic flora’ (including salt marshes) and N2000’s ‘Salt meadows’, WFD’s ‘fish fauna’ and N2000’s ‘fish-eating birds’, WFD’s ‘macrofauna’ and N2000’s ‘coastal breeding birds’ and ‘Large shallow bays’;  Gain more knowledge of the WFD (sub) quality elements by consulting experts at Rijkswaterstaat WVL, in order to improve decision-making on the contribution of (stakeholders’) initiatives to the achievement of WFD goals. Especially the WFD quality element ‘macrofauna’ requires more clarification;  Question the relevance of the assessment of the status of the WFD and N2000 goals in (River Basin) Management plans and monitoring data by looking at the monitoring method, time and location; Explore the possibilities of using more recent and relevant data to assess the status of a water body or specific goal, like the DPM’s monitoring data on birds and the MWTL monitoring data for the WFD (sub) quality elements;  Apply the research method on other WFD and N2000 water bodies, in order to gain insight in how initiatives from (external) stakeholders can contribute to the obligation to achieve the goals; Use the criteria set in the method to assess initiatives opportunistic or not for the implementation of the WFD and N2000;  Inform stakeholders of water body’s ecology on the WFD and N2000 goals and what they can gain from including the WFD and N2000 in their plans, like (governmental) support and financial means; Possibly organize an information session and discuss the applicability of the WFD and N2000 for stakeholders jointly;  Motivate stakeholders to inform Rijkswaterstaat about their plans in order to prevent missed opportunities to include the WFD and N2000 in their plans; Stay in touch with stakeholders in order to prevent missed opportunities;  Explore the possibility to quantify the contribution of initiatives to the WFD and N2000 goals and set quantified criteria for initiatives to be assessed as opportunistic or not; Get to know the application of the KRW-Verkenner and test it usefulness;

 Explore the effects (opportunities and threats) of the initiatives on external activities at the research areas, like the (shell)fish industry and recreation and involve stakeholders in the process.

For the specific opportunities at the Eastern Scheldt and Lake Grevelingen, it is recommended to:

 Stay informed on the locations of sand supplementation planned for the second phase (2025-2060) of the Eastern Scheldt’s Spatial Development Strategy. Supplementations of tidal flats located in front of salt marshes (see opportunities-map) contribute to the WFD and N2000 goals;  Explore the possibilities for implementing hard defences at salt marshes (see opportunities- map) at the Eastern Scheldt, in order to maintain them. Evaluate the feasibility of the Eastern Scheldt’s goals concerning salt marshes, due to the effects of sandhunger, and adapt the goals if necessary;  Stay informed on the results of the project ‘More value with mussels’ and explore expansion if the project proofs successful; Keep in touch with NIOZ about the research involving soft salt marsh defences at the island Griend and explore the application at the salt marshes at the Eastern Scheldt, seven-island plan and bird islands at Lake Grevelingen;  Include the Seven-island plan in the N2000 Management plans; Explore the possibilities to apply ecosystem engineers, similar to the island of Griend;  Stay updated on the decision to spend the available financial means for nature compensation at the Eastern Scheldt; Get involved in the nature compensation plans of Association Natuurmonumenten in order to combine the project with WFD and N2000 goals; Use one activity to support another, by using sediment retrieved from dredging to create (intertidal) land elsewhere;  Get involved in the allocation of the aquatic nature reserve at the Eastern Scheldt and motivate the choice for a location with Common seagrass (see opportunities-map);  Stay informed on the decision of preference concerning the project Getij Grevelingen and research the effects of the project on other initiatives at Lake Grevelingen, in order to assess the necessity of the initiatives;  Use the results of the experiments involving seagrass to successfully reintroduce Common seagrass during the third cycle of the WFD; Include the reintroduction of Common seagrass in the River Basin Management Plan and N2000 Management plan;  Contact Staatsbosbeheer and prevent missed opportunities to include initiatives, like the bird islands, in N2000 Management plans and explore opportunities to combine measures with aquatic nature at an early stage;  Learn from the Waddenmozaïek experiments and explore the possibilities to apply the subprojects at the Eastern Scheldt and Lake Grevelingen.

Finally, it is recommended to use the opportunities-map as a vision for the Eastern Scheldt and Lake Grevelingen.

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Thijs Poortvliet (Rijkswaterstaat Zee & Delta) Marjoke Muller (Rijkswaterstaat Water, Verkeer en Leefomgeving) Kees van der Vlugt (Stichting Het Zeeuwse Landschap) Frans van Zijderveld (Vereniging Natuurmonumenten)

Appendix 1: Background on research areas This Appendix is an elaboration of the background on the research areas. The information on the Eastern Scheldt and Lake Grevelingen is summarized in the Theoretical Framework (Chapter 2). A1.1 Eastern Scheldt The Eastern Scheldt is a coastal water that is part of the Scheldt river basin (Rijkswaterstaat, 2018). The area is part of the Natura 2000 network, and was assigned a National Park in 2002, making the Eastern Scheldt a nature area of international value (Witteveen+Bos, 2011; Stichting Nationaal Park Oosterschelde, sd). Its characteristics have changed over time with the construction of the Delta Works. According to Rijkswaterstaat (2016b), the most important functions at the Eastern Scheldt involve shipping and nature. Furthermore, the Eastern Scheldt’s purposes include water drainage, flood defence, cooling water, recreation, (professional) fishing, gaining surface minerals, aviation, research and monitoring. The Eastern Scheldt Vision 2018-2024 provides insight in the area’s ecological and economic developments, functions, ambitions and stakeholders (Slabbers, Brader, & Sorée, 2018). Furthermore, it is stated that the WFD and N2000 must be applied and that water safety must be guaranteed. A1.1.1 Management The Eastern Scheldt is managed by different water authorities. Rijkswaterstaat and Water Board Scheldestromen manage and maintain flood defences, the water system and infrastructural works (Rijkswaterstaat, 2016b). Rijkswaterstaat executes management of major waterways, water quantity and water quality. Water Board Scheldestromen manages polder discharges. Nature conservation (outside the dikes) is managed by Staatsbosbeheer, Association Natuurmonumenten, Het Zeeuwse Landschap, Water Board Scheldestromen and municipalities. Monitoring of birds, habitat and vegetation is managed by Province of Zeeland, owners of the area, Rijkswaterstaat and volunteers. A map of the working areas of the nature managers in the province of Zeeland is provided in Appendix 5. A1.1.2 Water network The Eastern Scheldt’s state in the Scheldt’s water network has been changed by the Delta Works that protect the land from flooding (Rijkswaterstaat, 2018). For this reason, the Eastern Scheldt is identified as a heavily modified water body, meaning its characters have changed due to physical alterations by human activity (European Parliament and the Council, 2000). The Eastern Scheldt storm surge barrier provides a protection level against a severe storm with a probability of occurring once every 4000 years (Witteveen+Bos, 2011). The lockable barrier only closes during threatening high water levels, tidal influences from the North Sea are still allowed when the barrier is open (Rijkswaterstaat, 2016b). Furthermore, sluices in the Grevelingendam and Zandkreekdam allow exchange of water between adjacent lakes Grevelingen and Veere. Other adjacent water bodies include the Scheldt-Rijn channel (separated by the Oesterdam) and Krammer (separated by the Philipsdam). Shipping routes remain connected via locks in all dams surrounding the Eastern Scheldt. A1.1.3 Pressures The North Sea’s tides and currents cause erosion and sedimentation processes at the Eastern Scheldt, creating tidal marshes, sand banks, shallow waters and deep tidal channels (Rijkswaterstaat, 2016b). The dynamics facilitate ecological values of international importance, like habitat for birds and plants. However the tidal action declined with thirty percent after the construction of the Delta Works (Van Zanten & Adriaanse, 2008). Fewer water flows in and out of the Eastern Scheldt, causing a decreased flow velocity. Consequently, transport of sedimentation has become unbalanced, since eroded sediment is transported to the tidal channels, however the sediment is not returned to

50 intertidal areas like sand banks and tidal flats. The intertidal areas become smaller and lower. The process is called ‘sandhunger’ (as shown in Figure A1), which results in the loss of sand banks and tidal flats, having negative effects on nature, dike conservation, shipping, recreation and fishing (Witteveen+Bos, 2011). In addition to sandhunger, the expected sea level rise of 60 centimetres by between 1990 and 2100 is accelerating the loss of intertidal areas. It is expected that by 2045, the Eastern Scheldt’s intertidal areas have decreased with fifty percent (Van Zanten & Adriaanse, 2008).

Figure A1 Cross-section illustrating the process of sandhunger. The grey area shows the erosion of intertidal areas in the period 1986-2001, while the yellow area shows the sedimentation moving to the deep channels. (Van Zanten & Adriaanse, 2008)

The loss of intertidal areas will have negative consequences on the short term (Witteveen+Bos, 2011). Firstly, intertidal areas attached to dikes act as a buffer for high waves. The loss of tidal flats and sand banks will affect the safety norm of the dikes, since wave impact has a direct effect on the dikes. Secondly, the intertidal areas form habitat for seals and protected birds (especially stilts), providing them with food. Smaller areas that fall dry for shorter times due to sandhunger will cause a shortage in food, which will eventually lead to a decline in population. Accordingly the Natura 2000 conservation goals are pressured. Thirdly, sandhunger is pressuring social-economic interests. Cockle fishing is occurs at the shrinking intertidal areas. Furthermore, the amount of visitors of the Eastern Scheldt’s nature might decrease. To conclude, the tidal channels experience sedimentation, which might require dredging in some areas to allow shipping.

Currently, Rijkswaterstaat is implementing sand supplementation at the Roggeplaat. The Roggeplaat is an intertidal area located in the north-western part of the Eastern Scheldt, as shown in Figure A2. Sand supplementation is a solution to the process of ‘sandhunger’, which is negatively affecting intertidal areas. Therefore, the Ministry of Infrastructure and Environment requested exploration in opportunistic measures to solve the problem. According to Witteveen+Bos (2011), experiments were implemented in order to gain insight in the effectiveness of measures: Pilot sand supplementation was executed at the Galgeplaat (2008); Oyster reefs are studied as erosion-limiting measures within the programme Building with Nature; The effectiveness of the combination of sand supplementation and oyster reefs were tested at the Schelphoek (2011); Study into supplementation strategies (2010); Study into consequences of sandhunger (ANT, 2013).

From the experiments and studies, it is concluded that sand supplementations successfully prevent sandhunger’s negative effects on nature (Witteveen+Bos & Bureau Waardenburg bv, 2013a). Construction might damage or disturb natural values, however only to values that benefit from the measure on the long term. Therefore the alternative of supplementation of 100 % is possible, conserving all sand banks and tidal flats. In order to realize the (N2000) conservation goals on the short term, solely the supplementation of the Roggeplaat is necessary (Witteveen+Bos & Bureau Waardenburg bv, 2013a). Secondly, it is concluded that sand supplementation (directly) at the Eastern Scheldt’s dikes will serve as an effective measure to reduce wave impact. The measure increases the dikes’ durability until 2060, when the dikes do not meet the water safety norms

51 anymore. The supplementations are a type of adaptive management, since they provide the opportunity to choose different methods for enhancing water safety: by enhancing the dikes or enhancing the foreland. Thirdly, it is concluded that the implementation of oyster reefs is an effective method to control erosion (Stichting Ecoshape, 2019a). More information about this project is given in paragraph 4.4.3.

Figure A2 The Spatial Development Strategy for the sand supplementations at the Eastern Scheldt. The first phase (2015- 2015) involves supplementation of the Roggeplaat, including a monitoring programme (red area)). The second phase (2025- 2060) involves determination of other supplementations (yellow-striped area). (Nieuwland, 2013)

By implementing supplementation of the Roggeplaat on the short term, the long-term strategy for tackling sandhunger for the whole area can be deferred until 2025. Uncertainties like sea level rise, development of erosion, population trends in stilts and efficiency of actual sand supplementation can be monitored, in order to make sufficient long-term decisions. The vision for the approach of sandhunger is shown in the Spatial Development Strategy in Figure A2. A1.2 Lake Grevelingen The Grevelingen is categorized as a salt water lake that is part of the Scheldt river basin (Rijkswaterstaat, 2018). The construction of the Delta Works has changed the lake’s ecological characteristics (Turlings, et al., 2009). According to Rijkswaterstaat (2016c), the most important functions of Lake Grevelingen involve professional fishing, nature and recreation. Furthermore, the Grevelingen’s purposes include water drainage, flood defence and shipping. The research area is Europe’s largest salt water lake and is part of the Natura 2000 network, making it a nature area of (inter)national importance.

A1.2.1 Management In order to conserve nature areas and recreational zones, nature is managed actively by Rijkswaterstaat, Staatsbosbeheer, Natuur- en Recreatieschap De Grevelingen, Zuid-Hollands Landschap, Water Board and private organisations (Rijkswaterstaat, 2016c). Rijkswaterstaat and Water Board Scheldestromen and Hollandse Delta manage and maintain flood defences, the water system and infrastructural works. Furthermore, Rijkswaterstaat executes management of major waterways, water quantity and water quality. Monitoring of birds, habitat, vegetation, water quality and dikes is managed by the Province, owners of the area, Rijkswaterstaat and volunteers. A map of the working areas of the nature managers in the province of Zeeland is provided in Appendix 5. A1.2.2 Water network Lake Grevelingen’s state in the Scheldt’s water network has been changed by the Delta Works that protect the land from flooding (Rijkswaterstaat, 2018). For this reason, Lake Grevelingen is identified as a heavily modified water body, meaning its characters has changed due to physical alterations by human activity (European Parliament and the Council, 2000). The Grevelingendam seperates the lake from the Eastern Scheldt and Krammer-Volkerak (Rijkswaterstaat, 2016c). A sluice allows exchange of water between the Grevelingen and Eastern Scheldt. Furthermore, a lock connects the shipping routes. The Brouwersdam closed the open connection to the North Sea. Consequently, the Grevelingen became a lake without tides. However, a sluice (Brouwerssluis) in the Brouwersdam still allows exchange of water. A1.2.3 Pressures Before the construction of the Delta Works, tides from the North Sea created tidal marshes and sand banks (Rijkswaterstaat, 2016c). The Grevelingendam cuts off supply of fresh water from rivers Rhine and Meuse, while the Brouwersdam cuts off the supply from the North Sea (Bouma, et al., 2008). The loss of tides in combination with a set target water level of -0,2 NAP changed the characteristics of Lake Grevelingen. Firstly, intertidal areas remained above water level permanently, while lower lying areas disappeared, having consequences for the lake’s species and their habitat (Van der Pluijm & De Jong, 2003). Secondly, salinity levels decreased due to a precipitation surplus (Hoeksema, 2002). Thirdly, the lack of tides is causing stratification and oxygen deficiency in the lake (Lengkeek, Bouma, & Waardenburg, 2007). Since the realization of the Delta Works, only wind power is mixing water layers. During warm seasons with a little wind, the lower water layer is not mixed with the warmer upper layer. Consequently, the bottom layer does not receive oxygen from the upper layer that is in contact with the surface. In addition, the degradation of algae (during warm seasons) is an oxygen- consuming process, contributing to the oxygen deficiency of the deeper areas of Lake Grevelingen. To conclude, increasing sedimentation due to lack of movement has caused a higher concentration of sludge in deep channels (Schaub, et al., 2002).

The consequences of the Delta Works affected Lake Grevelingen’s natural values negatively. Currently, a sluice in the Brouwersdam enables permanent exchange of water from the North Sea, improving natural processes (Hoeksema, 2002). The sluice has a positive effect on stratification and diversity of underwater-fauna. However, the inlet allows algae blooms into the lake, resulting in increased absence of oxygen in the deep channels. In the current situation, Lake Grevelingen is pressured by (Turlings, et al., 2009):

 Low oxygen concentration and stratification in deep channels, that causes unsuitable habitat for benthos;  Decrease of suitable breeding areas for birds due to succession of vegetation. Consequently, the conservation goals of N2000 might not be achieved;

 Possible decline of fish-eating birds;  Disappearance of seagrass, due to increased salinity. Consequently, the conservation goals of the WFD might not be achieved;  Accumulations of sea lettuce and algae blooms sink to the bottom of the lake, where degradation processes consume oxygen;  Mortality of benthic due to little to none oxygen in the deep water layers and sedimentation of sludge;  Increase in Japanese oysters, being nuisance to recreants. Furthermore, they can take other species’ habitat and food, which may lead to disappearance of species.

At Lake Grevelingen, the maximum surface of oxygen-free water (at the waterbed) is mainly found during the end of June and start of July (Smaal & Wijsman, 2014). The oxygen-free conditions usually last two to three months. Figure A3 provides a cross-section of the monitoring of oxygen in Lake Grevelingen in 2016 (Didderen, Bergsma, Driessen, & Lengkeek, 2016). It is shown that oxygen deficiency occurs in the deeper parts of the lake, near Scharendijke and Den Osse. Oxygen deficiency (as a result of stratification) of the bottom layer has a negative impact on benthic in the deeper parts of Lake Grevelingen (Wetsteijn, 2011). Furthermore, the inlet of Phaeocystis via the Brouwerssluis during spring enhances the oxygen deficiency. Managers aim to maintain the oxygen-deficient waterbed surface at less than five percent of the total surface.

Figure A3 TSO measurements of oxygen in Lake Grevelingen on June 22nd, 2016 (top diagram) and July 21st, 2016 (bottom diagram). The (left) x-as shows the depth in meters. The y-as shows the location of measurement, the diagram forms a cross-section of the lake. The colour scale shows the amount of oxygen measured in mg/L. (Didderen, Bergsma, Driessen, & Lengkeek, 2016)

Appendix 2: Background on the WFD and N2000 This chapter serves as an expansion of the background on the Water Framework Directive and Natura 2000. The information below is summarized in the Theoretical Framework (Chapter 2). A2.1 Water Framework Directive The European Water Framework Directive (WFD) aims to achieve and protect a sufficient state of inland surface waters, transitional waters, coastal waters and ground water (Article 1, WFD, European Parliament and the Council, 2000). The European Union provides its Member States with a Directive for goals, monitoring of water quality and taking measures, in order to achieve a sufficient ecological and chemical status of all waters. The EU Member States have result-obligation and effort- obligation to take measurs to reach the WFD goals. Furthermore, detoriation of the status of all water bodies must be prevented (art. 4, WFD). This paragraph mainly adressess surface waters, since the research areas are surface waters. Ground water plays a minor role. A2.1.1 Management In the Netherlands, the WFD involves multiple governmental organisations with the following tasks (Witteveen+Bos, et al., 2018a):

 Lead (take political responsibility): European Union, Ministry of Infrastructure and Water Management, Ministry of Economic Affairs and Climate Policy, and possibly the Ministry of Agriculture, Nature and Food Quality, provinces, water boards and Rijkswaterstaat;  Govern (management and implementation): Rijkswaterstaat, provinces and water boards;  Justify (take political and financial responsibility): Rijkswaterstaat, provinces and water boards. Direct link to EU via Informatiehuis Water;  Supervision (monitoring): Provinces and Ministry of Infrastructure and Water Management (department Human Environment and Transport Inspectorate).

EU Member states are required to translate the WFD goals into national legislation for implementation purposes (art. 24, WFD). The Dutch Ministry of Infrastructure and Environment has developed the National Water Plan on a strategic level, while regional plans have been developed by provinces (Witteveen+Bos, Royal HaskoningDHV, Colibrie Advies, & Twynsta Gudde, 2018b). On an operational level, National Water Management Plans have been developed by the Ministry of Infrastructure and Environment. Regional Water Management Plans have been developed by water boards. Furthermore, municipalities are allowed to take measures to achieve the WFD goals, however they are not obliged to. The WFD is included in the Dutch law by the ‘Decree on Quality Standards and Monitoring for Water 2009’ (Bkmw, 2009).

EU Member States identify national (and possibly transboundary) river basin districts, for which they ensure appropriate administrative arrangements (art. 3, WFD). The WFD (art. 2) defines a river basin as ‘’the area of land from which all surface run-off flows through a sequence of streams, rivers and, possibly, lakes into the sea at a single river mouth, estuary or delta’’. A river basin district is ‘’the area of land and sea, made up of one or more neighbouring river basins together with their associated ground waters and coastal waters (…)’’ (art. 2, WFD). Member States ensure the production of River Basin Management Plans (RBMP) (art. 13, WFD). A RBMP includes technical characteristics of the water bodies located in the river basin, the goals, measures and motivation for possible delays and exceptions for the achievement of the WFD goals. RBMPs are part of the National Water Plan, having corresponding cycles (Witteveen+Bos, et al., 2018b). Each cycle takes six years. Currently the measures planned for the second cycle are being executed (2016-2021) and preparation for the third cycle (2022-2027) has started (Witteveen+Bos, et al., 2018a). The management of river basins is

55 discussed during Regional Administrative Consultation Committees RBO in Dutch) and Regional Official Consultation Committees (RAO in Dutch), in which the national government, regional governmental departments and other stakeholders are represented.

Besides RBMPs, Member States are required to produce programmes that monitor the water status of water bodies within a river basin district (art. 8, WFD). Monitoring programmes provide an overview of the water status. Subsequently, the water status of surface waters and ground water can be assessed according to the WFD goals. A2.1.2 Categorization of water bodies A river basin exists of several water bodies. EU Member States have to analyse the characteristics of a river basin district, review the environmental impact of human activity and perform an economic analysis of the water use (art. 5 WFD). In order to do so, Member States must identify the location and boundaries of all surface water bodies and ground waters and categorize them (Annex II, WFD).

Surface water bodies in their natural state are categorized as rivers, lakes, transitional waters or coastal waters. In addition to the natural status, surface water bodies can be categorized as artificial or heavily modified. An artificial water body is a water body created by human activity (art. 2, WFD). A heavily modified water body is a surface water body which is substantially changed in character as a result of physical alterations by human activity (art. 2, WFD). The WFD uses two systems for differentiation of surface water types: System A differentiates water bodies according to descriptors within its ecoregion; System B differentiates water bodies according to valuation of descriptors within its river basin district, in order to set the ecological and chemical standards (goals) for a specific water body (Annex II, WFD). In the Netherlands, system B is used (Elbersen, Verdonschot, Roels, & Hartholt, 2003). In the categories of natural water bodies, each type has a name and code. For large natural water bodies, there are nine lake types, twelve river types, three coastal water types and one transitional water type, each having a reference standard for a sufficient status of the water body.

Besides location and boundaries, characterization of ground water bodies includes pressures, pollution sources, water abstraction, artificial recharge, dependent ecosystems and overlying layers in the catchment area (Annex II, WFD).

The WFD states that Member States have to register water bodies within a river basin district that are protected areas (art. 6, WFD). Protected areas are areas that ‘’have been designated as requiring special protection under specific Community legislation for the protection of their surface water and groundwater or for the conservation of habitats and species directly depending on water’’ (art. 6, WFD). Protected areas include areas designated for abstraction of water intented for human cosumption, protection of economically significant aquatic species, recreational waters (Directive 76/160/EEC), nutrient-sensitive areas (Directive 91/676/EEC & Directive 91/271/EEC) and protection of habitats or species (Natura 2000, Directive 92/43/EEC & Directive 79/409/EEC) (Annex IV, WFD). A2.1.3 Goals According to the WFD, each water body must achieve a sufficient ecological and chemical water status. For water bodies categorized as natural water bodies, the limit reference for a sufficient water status is the Good Ecological Status (GES) (art. 2, WFD). For natural water bodies, the goals (or standards) have been set nationally (Van der Molen, Pot, Evers, & Van Nieuwerburgh, 2012). The limit reference for artificial and heavily modified water bodies is the Good Ecological Potential (GEP), which is derived from the most similar natural water type. The majority of the Dutch water bodies are artificial or heavily modified. The highest score possible refers to the High Ecological Status (HES)

56 for natural water bodies and the Maximum Ecological Potential (MEP) for artificial and heavily modified water bodies.

The quality elements are divided in differrent categories and differ for each natural water type of surface water (Annex V, WFD). An overview is provided in Appendix 2. For artificial and heaviliy modified surface water bodies, the quality elements of the natural water type that resembles the water body closest are applied. The quality elements are divided in different categories. The ecological status includes the water bodies’ biology, physical chemistry and pollutants that may not exceed the set standards. The chemical status includes the water bodies’ ubiquitous substances and non-ubiquitous substances, which may not exceed the set standards.

The biological quality elements are measured in the Ecological Quality Ratio (EQR), which indicates the distance to the HES and MEP (Van der Molen, et al., 2012). The EQR for HES and MEP is 1, while the GEP and MEP are usually set at 0,6. Hydro morphological, chemical and physico-chemical elements support the biological elements (art. 4, WFD). Furthermore, the WFD includes priority substances and other pollutants that affect the biological quality elements. The pollutants refer to the Environmental Quality Standards (EQS) (European Parliament and of the Council, 2013). The EQS sets the Annual Average (AA-EQS) concentration per substance for inland surface waters and other surface waters. Furthermore, the EQS sets the Maximum Allowable Concentration (MAC-EQS) per substance for inland surface waters and other surface waters. For some substances, the EQS for biota is included. The EQS for pollutants are included in the RBMPs.

The deadline for achieving the sufficient status (GES or GEP) of all water bodies is by the end of the third cycle, in 2027 (Witteveen+Bos, et al., 2018a). However the time limit may be extended on the condition that further detoriation is prevented (art. 4, WFD). A delay in achieving the GEP and GES is permitted when improvements could not have been made within the time scope due to technical feasibility, high expensenses or natural conditions. Another requirement is a descriptive motivation for the postponement in the RBMP. Furthermore, the delay may not exceed two cycles and the measures that will be taken before the new deadline are described in the RBMP.

The WFD offers a possibility for less stringent environmental objectives if the natural condition makes the achievement of the GEP or GET impracticable, disproportionately expensive or if the water body’s characteristics are heavily affected by human activities (art. 4. WFD). Requirments to the application of less stringent objectives are: Achievement of the highest ecological and chemical status of surface waters possible; The least possible change to good ground water status; No further occurance of detoriation. Furthermore, the motivation for the less stringent objectives, including the new objectives are described in the RBMP. A2.1.4 Quality elements per type of surface water body The table on the next page shows the different WFD quality elements per category (Annex V, WFD). The blue-marked areas mean the quality element is applicable for the type of natural surface water body (rivers, lakes, transitional waters or coastal waters). For artificial and heaviliy modified surface

57 water bodies, the quality elements of the natural water type that resembles the water body closest are applied.

For each quality element, a standard (or reference) GES or GEP is set per surface water body. Each quality element is measured, so it can be assessed according to the standards. The quality elements ‘Hydrological regime’, ‘Morphological conditions’ and ‘Tidal regime’ contain sub-elements that are measured, as shown in the table. Then, it can be determined if the GES or GEP is sufficient and thus if the WFD goals are achieved.

Category Quality element Rivers Lakes Transitional Coastal waters waters

Composition, abundance and biomass of phytoplankton Composition and abundance of (other) aquatic flora

Biology Composition and abundance of benthic invertebrate fauna

Composition, abundance and age structure of fish fauna

• Quantity and • Quantity and dynamics of dynamics of water flow water flow Hydrological regime • Connection to • Residence time ground water • Connection to bodies the ground water body

River continuity Hydro morphological elements supporting • River depth • Lake depth • Depth variation • Depth variation the biological and width variation • Quantity, • Structure and elements variation • Quantity, structure and substrate of the • Structure and structure and substrate of the coastal bed Morphological condition substrate of the substrate of the bed • Structure of river bed lake bed • Structure of the intertidal • Structure of • Structure of the intertidal zone the riparian zone the lake shore zone

• Fresh water • Direction of flow dominant Tidal regime • Wave exposure currents • Wave exposure Thermal conditions Chemical and physico-chemical Oxygenation conditions elements supporting Salinity the biological Acidification status elements Nutrient conditions - General Transparancy

Category Quality element Rivers Lakes Transitional Coastal waters waters

Pollution by all priority substances identified as Chemical and being discharged into body physico-chemical of water elements supporting Pollution by other the biological substances identified as elements being discharged in - Specific pollutants significant quantities into the body of water

A2.2 Natura 2000 Natura 2000 (N2000) is a network of nature areas of European importance, aiming to safeguard Europe’s biodiversity (Ministerie van Landbouw, Natuur en Voedselkwaliteit, 2006). The Birds and Habitats Directives for specific N2000 areas serve as the main instruments to achieve this goal, by putting a protection status on birds and habitat species, including characteristic species. The Ministry of Agriculture, Nature and Food quality (2006) states that ‘’Member States of the European Union will take all necessary measures to ensure a ‘favourable conservation status’ of species and habitat types of Community importance’’. Nature areas are assigned to the network via a Designation Decree (Rijkswaterstaat, 2016a). Consequently, the conservation goals (criteria) for the N2000 area are determined. The N2000 goals do not have a strict deadline, however EU Member States are obliged to commit effort on taking measures that serve the N2000 goals and a vision for 2030 is made. A2.2.1 Management The European Birds Directive (2009) and Habitats Directive (1992) are secured in Dutch legislation by the Nature Protection Act (Wet Natuurbescherming, 2019). The act describes the terms of N2000 area designation, including the area’s conservation goals (art. 2.1, Nature Protection Act, 2019). ‘’Conservation means a series of measures required to maintain or restore the natural habitats and the populations of species of wild fauna and flora at a favourable status’’ (art. 1, Habitats Directive, 1992). Conservation goals exist of habitats conserving the birds according to the Birds Directive and habitats conserving the species according to the Habitats Directive. Furthermore the terms for permits for the implementation of projects in N2000 areas are described (art. 2.7, Nature Protection Act). Projects may not cause deterioration of the conservation goals (art. 6 Habitats Directive). The Nature Protection Act requires management plans for each N2000 area (art. 2.3). A management plan follows the same cycles of six years as the WFD (Rijkswaterstaat, 2016a).

Management plans describe the area-specific conservation goals, including the necessary conservation measures and their intended results (art. 2.3, Nature Protection Act). These conservation measures are defined as measures taken for preservation, maintenance or re- establishment of the desired diversity and area of habitats for all the species of birds applicable to the N2000 area (art. 3, Birds Directive, 2009). Furthermore, the conservation measures correspond with the ecological requirements of the natural habitat types applicable to the N2000 area and avoid deterioration of natural habitats and disturbance of their species (art. 6, Habitats Directive). The measures are the result of assessment of the conservation goals (Rijkswaterstaat, 2016a). Natural habitats are defined as ‘’terrestrial or aquatic areas distinguished by geographic, abiotic and biotic features, whether entirely natural or semi-natural’’ (art. 1, Habitats Directive). Besides conservation measures, mitigation of harmful human activities is included. The management plans include determination and prioritization of goals and determine the sense of urgency for specific habitats

59 and species (Ministerie van Landbouw, Natuur en Voedselkwaliteit, 2006). Accordingly, the conservation measures are prioritized.

On behalf of the Ministry of Infrastructure and Environment, Rijkswaterstaat takes the lead in the production of management plans for the Delta waters (Rijkswaterstaat, 2016a). Furthermore, the following roles and tasks are distinguished:

 Establishment of the Management plan: Ministry of Economic Affairs, Rijkswaterstaat and provinces;  Granting of permits according to the Nature Protection Act: provinces and Ministry of Economic Affairs;  Management and execution of conservation measures: Rijkswaterstaat, Association Natuurmonumenten, Staatsbosbeheer, Foundation Zuid-Hollands Landschap, Foundation Zeeuwse Landschap;  Regional governance: municipalities and water boards;  Mitigation of negative effects caused by human activity: stakeholders of the activity;  Monitoring of measures and their effects: qualified authority or stakeholder in owned management area, corresponding with the authority or stakeholder’s regular tasks;  Evaluation of monitoring and results: Rijkswaterstaat.

Rijkswaterstaat organizes sessions with regional parties for the drawing up of the management plans (Rijkswaterstaat, 2016a). At the Administrative Consultation Natura 2000 Delta waters (BOND in Dutch), qualified authorities make the decisions. The BOND is advised by the Administrative Advisory group Natura 2000 Delta waters (BAND in Dutch), consisting of administrative representatives of all sectors and local governmental departments. Regional boards existing of official representatives of interest groups and governmental departments supply local information. The information presented to the regional boards is also discussed by representatives of qualified authorities (OBG in Dutch). A2.2.2 Goals According to the Nature Protection Act (2019), N2000 acts on conservation goals, aiming to achieve a favourable status for natural habitats and the population of species of wild fauna and flora of community interest. (art. 1.1 Nature Protection Act; art 2 Habitats Directive). A natural habitat type is of community interest when the territory is endangered, has a small natural range or is a habitat listed in the Directive (art. 1, Habitats Directive). A species is of community interest when the species is endangered, vulnerable, rare or negatively exploited. Bird species applicable to the N2000 are species that are in danger of extinction, vulnerable to change in habitat, rare, or require attention because of the specific nature in their habitat (art. 4, Birds Directive).

A natural habitat’s status is considered favourable when the habitat meets the following requirements (art. 1, Habitats Directive):

 ‘’It’s natural range and areas it covers within that range are stable or increasing;  The specific structure and function which are necessary for its long-term maintenance exist and are likely to continue to exist for the foreseeable future;  The conservation status of its typical species is favourable.’’

The conservation status of a species is considered favourable when (art. 1 Habitats Directive):

 ‘’Population dynamics data on the species concerned indicate that it is maintaining itself on a long-term basis as a viable component of its natural habitats;

 The natural range of the species is neither being reduced nor is likely to be reduced for the foreseeable future;  There is and will probably continue to be, a sufficiently large habitat to maintain its populations on a long-term basis.’’

Table 2 (see Chapter 2, paragraph 2.3.2) shows the types and clusters of conservation goals, as categorized in the Management plan for the Delta waters (Rijkswaterstaat, 2016a). For each type named in Table 2, the conservation goals applicable to the N2000 area are assigned. Only if all assigned species and habitat types can survive sustainably, the Netherlands is taking its responsibility for the conservation of European biodiversity. The national goals are assessed according to its relative importance to the European goals, and then categorized in classes (Ministerie van Landbouw, Natuur en Voedselkwaliteit, 2006). In the Netherlands, the classes are defined as of high (class A), medium (class B) or of considerable (class C) national relative importance to the European goals. Furthermore, the habitats and species are assessed according to the N2000 area specific goals. The Management plan describes the goals and trends, from which the status of habitats and species can be concluded. The status can be favourable, moderate unfavourable or unfavourable. In the Management plan, the obstacle causing the unfavourable status is described (Rijkswaterstaat, 2016a). Based on the conservation goals and their assessment, management measures can be elaborated, forming the basis of the N2000 Management plan.

The management plans show whether a conservation goal is achieved with the current management (Rijkswaterstaat, 2016a). If not, the conservation measures necessary to achieve the favourable status are described. Consequently, it is assessed if the favourable status might be achieved after the implementation of the conservation measures.

On the short term, the conservation goals do not have to be achieved completely (Rijkswaterstaat, 2016a). However, deterioration in quantity and quality of habitat types and species has to be stopped within the first six year cycle, as ecosystems might not be able to recover. In addition, conservation measures may have higher costs in the future if the deterioration is not stopped. On the long term, the conservation goals for Delta waters must be met by approximately 2030. The vision for 2030 is to have continued multifunctional N2000 areas with large economic and recreational values, where robust ecosystems host special natural values.

Appendix 3: WFD References and scales A3.1 K2 A3.1.1 Biology The table below shows the biological references and scales for the applicable (sub) quality elements for the water type K2, according to STOWA (2012).

Quality element Sub quality element High status Good status Moderate Moderate status Bad (limit: (limit) status (limit: (limit) / Status (limit) / HES/MEP) / GES/GEP) Insufficient Insufficient Reference Phaeocystis blooming 0 10 17 42 84 frequency (%) Chlorofyl-a Phytoplankton 9,3 14 21 42 84 (90-p; µg/l) EQR 1,0 0,8 0,6 0,4 0,2 Final judgement = EQR Phytoplankton = (EQR (Phaeocystis) + EQR (Chlorofyl-a))/2 Salt marsh (% of total 13 10 7 4 2 water body) (Schorren) Salt marsh quality 5 4,5 3,5 2,5 1,5 (credits) (Schorren) Seagrass area (% of 7,5 5 4 2 1 total water body) Seagrass quality (% coverage dwarf 60 54 42 30 18 seagrass) Seagrass quality Other aquatic (% coverage common 30 27 21 15 9 flora seagrass) EQR 1,0 0,8 0,6 0,4 0,2 Final judgement = EQR Aquatic flora =

Polyhaline-Intertidal  36 - 45 27 - 36 18 - 27 9 - 18 0 - 9 Species richness (S) Ref. = 45* Polyhaline-Intertidal  3,0 – 3,7 Shannon Index (log2) 2,2 – 3,0 1,5 – 2.2 0,7 – 1,5 0 – 0,7 Ref. = 3,7* (H) Polyhaline-Subtidal  54 - 67 40 - 54 27 - 40 13 - 27 0 - 13 Species richness (S) Ref. = 67* Polyhaline-Subtidal  Macrofauna: 4,1 – 5,1 Shannon Index (log2) 3,1 – 4,1 2,0 – 3,1 1,0 - 2,0 0 – 1,0 Benthic Ref. = 5.1* invertebrate (H) fauna *** AMBI 0 – 1,2 1,2 – 2,4 2,4 – 3,6 3,6 – 4,8 4,8 - 6 Ref. = 0 EQR 0,8 – 1,0 0,6 - 0,8 0,4 – 0,6** 0,2 – 0,4 0 – 0,2 Ref. = 1 Final judgement = EQR Macrofauna = ‘’BEQI2 = (EQR(S) + EQR(H) + EQR(AMBI))/3 EQR(S) = S(sample)/S(ref.) EQR(H) = H(sample)/H(ref.) EQR(AMBI) = (AMBI(bad) – AMBI(sample)) / (AMBI(bad) – AMBI(ref.))’’ (Van Loon, et al., 2015). * The sample waterbed surface is approxemately 0,1 m2 ** GEP/GES ≥ 0,6 *** BEQI2 = Bentic Ecosystem Quality Index; Species richness = number of species in sample; Shannon Index measures abundance; AMBI measures sensitiviy of species for disturbance by using the Borja formula.

A3.1.2 Hydro morphology The table below shows the hydro morphological WFD quality element relevant for the water type K2, according to according to STOWA (2012).

Quality element Range HES / MEP Natural shores (%) 80 - 100

A3.1.3 Physical chemistry The table below shows the physio-chemistry references and scales for the applicable (sub) quality elements for the water type K2, according according to STOWA (2012).

A3.2 M32 A3.2.1 Biology The table below shows the biological references and scales for the applicable (sub) quality elements for the water type M32, according to STOWA (2012).

Quality element Sub quality element High status Good status Moderate Moderate status Bad (limit: (limit) status (limit: (limit) / Status (limit) / HES/MEP) / GES/GEP) Insufficient Insufficient Reference Phaeocystis blooming 0 10 17 35 80 frequency (%) Chlorofyl-a Phytoplankton 8 12 18 36 72 (90-p; µg/l) EQR 1,0 0,8 0,6 0,4 0,2 Final judgement = EQR Phytoplankton = (EQR (Phaeocystis) + EQR (Chlorofyl-a))/2 Seagrass quantity (% 65 – 100 surface area with 50 - 65 35 – 50 20 - 35 0 - 20 Ref. ≥ 90 possible coverage) Seagrass quality (% surface area of 50 – 100 40 – 50 30 – 40 15 – 30 0 - 15 Other aquatic seagrass field with Ref. ≥ 50 flora coverage > 60%) EQR 0,8 – 1,0 0,6 – 0,8 0,4 – 0,6** 0,2 – 0,4 0 – 0,2 Final judgement = EQR Aquatic flora =

Species richness (S) 35 – 44 26 – 35 18 – 26 9 – 18 0 – 9 Ref. = 44* Shannon Index (log2) 3,3 – 4,2 2,5 – 3,3 1,7 - 2,5 0,8 – 1,7 0 – 0,8 (H) Ref. = 4,2* AMBI 0 – 1,2 Macrofauna: 1,2 – 2,4 2,4 – 3,6 3,6 – 4,8 4,8 - 6 Benthic Ref. = 0 invertebrate EQR 0,8 – 1,0 0,6 – 0,8 0,4 – 0,6** 0,2 – 0,4 0 – 0,2 fauna **** Ref. = 1,0 Final judgement = EQR Macrofauna = ‘’BEQI2 = (EQR(S) + EQR(H) + EQR(AMI))/3 EQR(S) = S(sample)/S(ref.) EQR(H) = H(sample)/H(ref.) EQR(AMBI) = (AMBI(bad) – AMBI(sample)) / (AMBI(bad) – AMBI(ref.))’’ (Van Loon, et al., 2015). CA*** (amount of 4 – 10 3 – 4 2 – 3 1 – 2 0 – 2 species Ref. ≥ 5 ER*** (amount of 8 – 14 6 – 8 4 – 6 2 – 4 0 - 2 species) Ref. ≥ 10 MJ*** + MS*** 11 – 18 8 – 11 5 – 8 2 - 5 0 – 2 (amount of species) Ref. ≥ 14 Z1*** + Z2*** (amount 4 – 11 3 – 4 2 – 3 1 – 2 0 – 1 of species) Ref. ≥ 5 CA*** (biomass %) 8 – 100 6 – 8 4 – 6 2 – 4 0 - 2 Fish fauna Ref. ≥ 10 ER*** (biomass %) 8 – 100 6 – 8 4 – 6 2 – 4 0 - 2 Ref. ≥ 10 MJ*** + MS*** 15 – 100 10 – 15 5 – 10 2 – 5 0 - 2 (biomass %) Ref. ≥ 20 Z1*** + Z2*** 8 – 100 6 – 8 4 – 6 2 – 4 0 - 2 (biomass %) Ref. ≥ 10 EQR 0,8 – 1,0 0,6 – 0,8 0,4 – 0,6** 0,2 – 0,4 0 – 0,2 Ref. = 0 EQR = ((sum indicators species)/5 + (sum indicators biomass)/6) /2 * The sample waterbed surface is approxametely 0,1 m2 ** GEP/GES ≥ 0,6 *** CA: Diadromous species; ER: Estuarine residents; MJ: Marine juveniles; MS: Marine seasonal quests; Z1: Fresh-water species, choride-tolerance ≤ 8 g/l; Z2: Fresh-water species, chloride-tolerance ≤ 4 g/l

**** BEQI2 = Bentic Ecosystem Quality Index (second version); Species richness = number of species in sample; Shannon Index measures abundance; AMBI measures sensitiviy of species for disturbance by using the Borja formula. A3.2.2 Hydro morphology The table below shows the hydro morphological WFD quality element applicable for water type M32, according to according to STOWA (2012).

Quality element Low reference High reference Accountability Surface variation (km2) 5 140 Expert judgement Water depth (m) 0,10 7 1 Water depth variation (m3) 0 8,4 Expert judgement Volume (m3) 7 199 * 106 Calculation Residence time (year) 0,3 7,4 Calculation Seepage (0/1) 0 1 Expert judgement Bottom surface/volume 10,4 0,40 Calculation Slope bank profile (degree) 10 70 Expert judgement

A3.2.3 Physical chemistry The table below shows the physio-chemistry references and scales for the applicable (sub) quality elements for the water type M32, according according to STOWA (2012).

Quality element Sub quality element High status Good status Moderate Moderate Bad (limit: (limit: status status (limit) / Status (limit) / HES/MEP) / GES/GEP) Insufficient Insufficient Reference Thermal Daily value (Celcius) ≤ 23 ≤ 25 25 – 27,5 27,5 – 30 > 30 conditions Salinity Chlorinity (mg C /l) 10000 – 18000 > 10000 9000 – 10000 8000 – 9000 < 8000 Acidity pH 9,0 – 9,5 6,5 – 9,0 6,5 – 9,0 9,5 – 10,0 > 10,0 < 6,5 Oxygen balance Saturation (%) 50 - 60 40 – 50 80 - 120 60 - 120 < 40 120 - 130 130 - 140 Nutrients Winter DIN (mg N /l)* ≤ 0,22 ≤ 0,46 0,46 – 0,77 0,77 – 0,92 > 0,92 Winter DIN ≤ 15,6 ≤ 33 33 – 55 55 – 66 > 66 (µmol N /l)* Transparency SD (m) ≥ 2,0 ≥ 0,9 0,6 – 0,9 0,45 - 0,6 < 0,45 * The values for nitrogen are winter values (December until February) with a salinity of 30 or higher. For lower salinity, the standard for nitrogen (mg N /l) = 2,59 – 0,071 * salinity. A3.3 Pollutants The table below shows the EQS for pollutants applicable to both the Eastern Scheldt and Lake Grevelingen, according to the RMBP Scheldt 2016-2021 (Ministerie van Infrastructuur en Milieu, 2015).

Substance AA-EQS inland surface waters MAC-EQS inland surface waters Arsenic, dissolved (µg/l) 0,5 8 Silver, dissolved (µg/l) 0,01 0,01

A3.4 Ubiquitous substances The table below show the EQS for ubiquitous substances applicable to both the Eastern Scheldt and Lake Grevelingen, according to the Directive on priority substances (European Parliament and of the Council, 2013). Furthermore, the MAC for biota is given for mercury.

Substance MAC-EQS inland surface waters MAC Biota Benzo(ghi)perylene 8,2 × 10-3 µg/l Not applicable Mercury 0,07 µg/l 20 µg/kg

Appendix 4: N2000 Conservation goals and status of research areas In this Appendix, the N2000 conservation goals are provided specifically for the Eastern Scheldt and Lake Grevelingen. The legends for the tables in A4.1 Eastern Scheldt and A4.2 Lake Grevelingen are provided on the next page.

In order to determine the status of the research areas according to the N2000 goals, monitoring was performed, its results shown in the N2000 management plans (Rijkswaterstaat, 2016a). Rijkswaterstaat is responsible for the monitoring and evaluation of the N2000 habitat types and species. The species of water birds and sea mammals are counted by Delta Project Management, as requested by Rijkswaterstaat (Arts, et al., 2018). From the monitoring results, conclusions are made in the management plans. Conclusion on the conservation goals and their status are made every six years (following the cycles of the management plans) (Van Beek, Van Rosmalen, Van Tooren, & Van der Molen, 2014). Furthermore, the amount of species monitored is shown, the trend, national conservation status, relative importance and method for conservation is shown according the Management plan (Rijkswaterstaat, 2016b).

Monitoring of species is performed monthly, from the shore, boats and airplanes during high tides, when birds locate themselves at higher grounds (Arts, et al., 2018). The counting is done by professionals (from Rijkswaterstaat, Staatsbosbeheer and Province of Zeeland) and volunteers, who communicate countings to assure accurate monitoring results. For the monitoring of habitat, the method of vegetation mapping is used, in which assessment is performed of the presence, abiotic factors, presence of typical species and other factors determining the sufficient functioning of the habitat type (Van Beek, et al., 2014). The current monitoring results are from the period 2006/2007 until 2010/2011 (Rijkswaterstaat, 2016b+c).

In this Appendix, the conservation goals are shown according to the Designation Decree Eastern Scheldt (Minister van Landbouw, Natuur en Voedselkwaliteit, 2009) and Designation Decree Lake Grevelingen (Staatssecretaris van Economische Zaken, 2013). Furthermore, the amount of animals per species is shown, the trend, national conservation status, relative importance and method for conservation is shown according the Management plan (Rijkswaterstaat, 2016b+c). In the Management plan it is concluded whether the conservation goal is facing obstacles, which determines if measures are required for the realisation of the conservation goal on the short term (within 1st cycle of six years) and long term (2nd cycle or later). If a conservation goal is expected to be realised by implementing measures, the specific measures are described in the Management plan. From the Management plan, it can be concluded that the combination of all measures set are sufficient to realize the unfavourable goals on the short term. For goals facing possible obstacles in the future, it is unknown whether the goal will be realized on the long term.

Legend Applicable to: 1 2 3 4 5 6 Species Counted average pares of Minimum conservation goal Trends area (2002-2011) National status of Relative importance area Type of conservation species (2006/2007- of pares of species -  Moderate decrease conservation -  <2% of Dutch population M  Maintenance 2010/2011) 0  stable --  highly unfavourable +  2-15 % of Dutch I  Improvement -  Less than goal +  moderate increase -  moderate unfavourable population E  Expansion of areal 0  Same as goal ++  strong increase +  favourable ++ 15-50% of Dutch +  Higher than goal ?  unknown population +++  >50% of Dutch population

Habitat types Not applicable Not applicable Trends area (2002-2011) National status of Relative importance area Type of conservation -  Moderate decrease conservation -  <2% surface area, mainly M  Maintenance 0  stable --  highly unfavourable moderate quality I  Improvement +  moderate increase -  moderate unfavourable +  >15% surface area, E  Expansion of areal ++  strong increase +  favourable mainly moderate quality / 2- ?  unknown 15% surface area / <2% surface area, mainly good quality ++  >15% surface area, mainly good quality / special quality / special geographical location and good quality

Conservation goal is not achieved with current management. Conservation goal is achieved with current management, however might not be achieved in the next cycle . Conservation goal is achieved with current management. Amount of species is below the conservation goal / There is a negative trend. Yet the capacity of the area is sufficient. Conservation goal will be achieved due to implementing measures. No deterioration due to the implementation of measures. It is unknown whether the conservation goal will be achieved. Conservation goal will probably be achieved. (r) Regional goal of the region ‘Delta Waters’.

A4.1 Eastern Scheldt The table below shows the species and habitat types applicable to the N2000 area Eastern Scheldt, according to the Designation Decree (Minister van Landbouw, Natuur en Voedselkwaliteit, 2009). The conservation goals and obstacles are shown, indicating whether the goals are met, according to the Management plan Eastern Scheldt (Rijkswaterstaat, 2016b).

Habitat type/ EU - code Amount1 Min. Trend3 National Relative Goal Goal Obstacle Realisation goal Realisation goal Species conservation conservation import- habitat habitat short term (<6 long term (>6 goal2 status4 ance5 quantity quality6 years, 1st cycle) years, 2nd cycle or 6 later) Coastal breeding birds Vegetation succession, predators and insufficient resting. New Kentish Plover (r) A138 (-) 27 60 ? -- + E I breeding areas do not No deterioration Unknown Strandplevier develop naturally (anymore). In future: sandhunger. Yes, by Common Tern (r) Possible future; A193 (0) 1109 1109 0 - + M M implementing Yes Visdief vegetation succession. measures. Marsh breeding birds Western Marsh Harrier A081 ? 19 ? + - M M Unknown Unknown Yes Bruine kiekendief Stilts Common Ringed Possible future: decrease Plover A137 0 280 0 + + M M foraging area due to Yes Unknown Bontbekplevier sandhunger. Possible future: decrease Dunlin A149 + 14100 0 + + M M foraging area due to Yes Unknown Bonte strandloper sandhunger. Possible future: decrease Sanderling A144 + 260 ++ - + M M foraging area due to Yes Unknown Drieteenstrandloper sandhunger. European Golden Plover A140 0 113 ++ -- + M M No Yes Yes Goudplevier Common Possible future: decrease Greenshank A164 0 150 ? + + M M foraging area due to Yes Unknown Groenpootruiter sandhunger. Possible future: decrease Red Knot A143 0 7700 - - ++ M M foraging area due to Yes Unknown Kanoet sandhunger. Northern Lapwing A142 0 4500 ? - - M M No Yes Yes Kievit

Habitat type/ EU - code Amount1 Min. Trend3 National Relative Goal Goal Obstacle Realisation goal Realisation goal Species conservation conservation import- habitat habitat short term (<6 long term (>6 goal2 status4 ance5 quantity quality6 years, 1st cycle) years, 2nd cycle or 6 later) Stilts Possible future: decrease Pied Avocet A132 + 510 0 - + M M foraging area due to Yes Unknown Kluut sandhunger. Possible future: decrease Bar-tailed Godwit A157 0 4200 0 + + M M foraging area due to Yes Unknown Rosse grutto sandhunger. Eurasian Possible future: decrease Oystercatcher A130 0 24000 - -- ++ M M foraging area due to Yes Unknown Scholekster sandhunger. Possible future: decrease Ruddy Turnstone A169 + 580 + -- ++ M M foraging area due to Yes Unknown Steenloper sandhunger. In future: decrease Yes, by Kentish Plover A138 - 50 ? -- + M M foraging area due to implementing Unknown Strandplevier sandhunger. measures. Possible future: decrease Common Redshank A162 + 1600 + - + M M foraging area due to Yes Unknown Tureluur sandhunger. Possible future: decrease Eurasian Curlew A160 + 6400 ++ + + M M foraging area due to Yes Unknown Wulp sandhunger. Possible future: decrease Grey Plover A141 + 4400 + + ++ M M foraging area due to Yes Unknown Zilverplevier sandhunger. External: Cause for decrease amount of Spotted Redshank birds unknown. In A161 - 310 - + ++ M M Yes Unknown Zwarte ruiter future: decrease foraging area due to sandhunger. Fish-eating birds Great Cormorant A017 + 360 0 + - M M No Yes Yes Aalscholver Little Grebe A004 + 80 + + + M M No Yes Yes Dodaars

Habitat type/ EU - code Amount1 Min. Trend3 National Relative Goal Goal Obstacle Realisation goal Realisation goal Species conservation conservation import- habitat habitat short term (<6 long term (>6 goal2 status4 ance5 quantity quality6 years, 1st cycle) years, 2nd cycle or 6 later) Fish-eating birds Great Crested Grebe A005 0 370 ? - + M M No Yes Yes Fuut Little Egret A026 + 20 ? + + M M No Yes Yes Kleine zilverreiger Horned Grebe A007 + 8 ++ + ++ M M No Yes Yes Kuifduiker Eurasian Spoonbill A034 + 30 ++ + + M M No Yes Yes Lepelaar Red-breasted Merganser A069 0 350 ? + + M M No Yes Yes Middelste zaagbek Ducks, geese and swans Cause for decrease amount of birds Common Shelduck A048 - 2900 - + + M M unknown. In future: No deterioration Unknown Bergeend decrease foraging area due to sandhunger. Barnacle Goose A045 + 3100 ++ + + M M No Yes Yes Brandgans Cause for decrease Common Goldeneye A067 - 680 - + + M M amount of birds No deterioration Likely Brilduiker unknown. Greylag Goose A043 + 2300 + + + M M No Yes Yes Grauwe gans Tundra swan A037 N.A. N.A. ? - S+ M M No Yes Yes Kleine zwaan Gadwall A051 + 130 ? + - M M No Yes Yes Krakeend Cause for decrease Eurasian Coot A125 - 1100 ? - - M M amount of birds No deterioration Likely Meerkoet unknown.

Habitat type/ EU - code Amount1 Min. Trend3 National Relative Goal Goal Obstacle Realisation goal Realisation goal Species conservation conservation import- habitat habitat short term (<6 long term (>6 goal2 status4 ance5 quantity quality6 years, 1st cycle) years, 2nd cycle or 6 later) Ducks, geese and swans Cause for decrease amount of birds Northern Pintail A054 - 730 - - + M M unknown. In future: No deterioration Unknown Pijlstaart decrease foraging area due to sandhunger. Brant Goose A046 0 6300 0 - ++ M M No Yes Yes Rotgans Cause for decrease Northern Shoveler A056 - 940 - + + M M amount of birds No deterioration Likely Slobeend unknown. Eurasian Wigeon A050 0 12000 ? + + M M No Yes Yes Smient Mallard A053 0 5500 0 + - M M No Yes Yes Wilde eend Eurasian Teal A052 + 1000 ? - - M M No Yes Yes Wintertaling Birds of prey Peregrine Falcon A103 + 10 (max.) ? + + M M No Yes Yes Slechtvalk Habitat species Possible future; decrease potential resting-, moulting- and Yes, by Common Seal (r) H1365 N.A. N.A. ? + - I I reproduction area due implementing Yes Gewone zeehond to sandhunger. measures. Measures required to improve habitat. Decrease habitat’s Yes, by Root Vole quality & quantity. H1340 N.A. N.A. ? -- + E M implementing Yes Noordse woelmuis Expansion goal not measures. automatically achieved. Habitat types Large shallow bays Decrease due to H1160 N.A. N.A. ? -- ++ M I Yes Unknown Grote baaien ‘Sandhunger’.

A4.2 Lake Grevelingen The table below shows the species and habitat types applicable to the N2000 area Eastern Scheldt, according to the Designation Decree (Staatssecretaris van Economische Zaken, 2013). The conservation goals and obstacles are shown, indicating whether the goals are met, according to the Management plan Eastern Scheldt (Rijkswaterstaat, 2016c).

Habitat type/ EU - code Amount1 Min. Trend3 National Relative Goal Goal Obstacle Realisation goal Realisation goal Species conservation conservation import- habitat habitat short term (<6 long term (>6 goal2 status4 ance5 quantity quality6 years, 1st cycle) years, 2nd cycle or 6 later) Coastal breeding birds Common Ringed Yes, by E – I not automatically Plover (r) A137 0 (28) 28 + -- + E I implementing Yes achieved. Bontbekplevier measures. Little Tern A195 0 (190) 190 ++ -- + M M No Yes Yes Dwergstern Possibly future; Yes, by Sandwich Tern (r) Predation and lack of A191 0 (989) 989 ? -- ++ M M implementing Yes Grote stern suitable breeding measures. locations. Pied Avocet (r) E – I not automatically A132 - (363) 410 + - + E I No deterioration Yes Kluut achieved. E – I not automatically achieved. Pressured Kentish Plover (r) breeding population A138 - (70) 110 0 -- ++ E I No deterioration Likely Strandplevier Mediterranean Sea pressured, possibly influencing deltas. Predation. Yes, by Common Tern (r) A193 - (732) 2700 + - + E I E – I not automatically implementing Yes Visdief achieved. measures. Marsh breeding birds Western Marsh Highly set goal. Yes, by Harrier A081 - 20 0 + - M M Expansion habitat implementing Yes Bruine kiekendief necessary. measures.

Habitat type/ EU - code Amount1 Min. Trend3 National Relative Goal Goal Obstacle Realisation goal Realisation goal Species conservation conservation import- habitat habitat short term (<6 long term (>6 goal2 status4 ance5 quantity quality6 years, 1st cycle) years, 2nd cycle or 6 later) Stilts Common Ringed Plover A137 + 50 ? + - M M No Yes Yes Bontbekplevier Dunlin A149 0 650 ? + - M M No Yes Yes Bonte strandloper European Golden Plover A140 - 2600 ? -- + M M External Yes Yes Goudplevier Pied Avocet A132 + 80 0 - - M M No Yes Yes Kluut Bar-tailed Godwit A157 + 30 ? + - M M No Yes Yes Rosse grutto Eurasian Oystercatcher A130 - 560 - -- - M M External Yes Yes Scholekster Ruddy Turnstone A169 - 30 - -- - M M No Yes Yes Steenloper Kentish Plover A138 + 20 + -- + M M No Yes Yes Strandplevier Common Redshank A162 - 170 0 - - M M No Yes Yes Tureluur Eurasian Curlew A160 + 440 ? + - M M No Yes Yes Wulp Grey Plover A141 - 130 + + - M M No Yes Yes Zilverplevier Fish-eating birds Great Cormorant A017 0 310 0 + - M M No Yes Yes Aalscholver Little Grebe A004 + 70 + + + M M No Yes Yes Dodaars Great Crested Grebe Unknown; Too little fish A005 - 1600 - - + M M No deterioration Yes Fuut is expected. Black-necked Grebe A008 + 1500 0 - +++ M M No Yes Yes Geoorde fuut

Habitat type/ EU - code Amount1 Min. Trend3 National Relative Goal Goal Obstacle Realisation goal Realisation goal Species conservation conservation import- habitat habitat short term (<6 long term (>6 goal2 status4 ance5 quantity quality6 years, 1st cycle) years, 2nd cycle or 6 later) Fish-eating birds Little Egret A026 - 50 -- + ++ M M No Yes Yes Kleine zilverreiger Unknown; Too little fish Horned Grebe A007 - 20 ? + ++ M M is expected. Very low No deterioration Yes Kuifduiker amount of individuals. Eurasian Spoonbill A034 0 70 ? + + M M No Yes Yes Lepelaar Red-breasted Merganser A069 0 1900 0 + +++ M M No Yes Yes Middelste zaagbek Duck, geese and swans Common Shelduck A048 + 700 + + - M M No Yes Yes Bergeend Barnacle Goose A045 + 1900 + + - M M No Yes Yes Brandgans Common Goldeneye A067 - 620 - + + M M Unknown No deterioration Likely Brilduiker Greylag Goose A043 + 630 ++ + - M M No Yes Yes Grauwe gans Tundra swan A037 + 4 ++ -- - M M No Yes Yes Kleine zwaan Greater White- fronted Goose A041 - 140 - + - M M External Yes Yes Kolgans Gadwall A051 0 320 ? + - M M No Yes Yes Krakeend Eurasian Coot A125 + 2000 + - - M M No Yes Yes Meerkoet Northern Pintail A054 + 60 + - - M M No Yes Yes Pijlstaart Brant Goose A046 + 1700 + - + M M No Yes Yes Rotgans Northern Shoveler A056 + 50 + + - M M No Yes Yes Slobeend

Habitat type/ EU - code Amount1 Min. Trend3 National Relative Goal Goal Obstacle Realisation goal Realisation goal Species conservation conservation import- habitat habitat short term (<6 long term (>6 goal2 status4 ance5 quantity quality6 years, 1st cycle) years, 2nd cycle or 6 later) Duck, geese and swans Eurasian Wigeon A050 0 4500 0 + - M M No Yes Yes Smient Mallard A053 - 2900 0 + - M M External Yes Yes Wilde eend Eurasian Teal A052 - 510 0 - - M M No Yes Yes Wintertaling Birds of prey Peregrine Falcon A103 0 10 (max.) 0 + + M M No Yes Yes Slechtvalk Habitat species Fen Orchid H1903 N.A. N.A. + -- ++ M M No Yes Yes Groenknolorchis Decrease habitat’s quality & quality due to Yes, by Root Vole forest development and H1340 N.A. N.A. - -- ++ E I implementing Yes Noordse woelmuis (intensive) grazing. E – I measures. not automatically achieved. Habitat types Sea buckthorn M H2160 N.A. N.A. 0 + + M No Yes Yes Duindoornstruwelen M Grey Dunes (lime- deficient) H2130_B N.A. N.A. 0 -- - M M No Yes Yes Grijze duinen (kalkarm) Creeping Willow H2170 N.A. N.A. 0 + + M M No Yes Yes Kruipwilgstruwelen Great Willow Herb H6430_B N.A. N.A. 0 - - M M No Yes Yes Harig wilgenroosje In dike salt meadows Possible future; lack of Schorren en zilte dynamics, desalinisation H1330_B N.A. N.A. 0 - + M M Yes Unknown graslanden and vegetation (binnendijks) succession.

Appendix 5: List of stakeholders The table below shows the stakeholders of the Eastern Scheldt and Lake Grevelingen. Key stakeholders were already mentioned in Chapter 2. The stakeholders are categorized by sector. The stakeholders in the table are managers of the WFD and N2000, spatial developers or are affected by (possible) developments. In addition, a map (see Figure A3) is provided with all nature managers at the province of Zeeland.

Sector Stakeholders of the research areas European Union Ministry of Infrastructure & Water Management Ministry of Economic Affairs and Climate Policy Ministry of Agriculture, Nature and Food Quality Rijkswaterstaat Zee & Delta Province of Zeeland Province of Zuid-Holland Government / Water board Scheldestromen Management Water board Hollandse Delta Municipality of Schouwen-Duiveland Municipality of Goerree-Overflakkee Municipality of Tholen Municipality of Reimerswaal Municipality of Kapelle Municipality of Goes Municipality of Noord-Beveland Staatsbosbeheer Association Natuurmonumenten Foundation Zuid-Hollands Landschap Foundation Zeeuwse Landschap Nature Natuur- en Recreatieschap De Grevelingen Nationaal Park Oosterschelde Foundation de Oosterschelde Delta Project Management (DPM) HZ University of Applied Sciences Wageningen Marine Research Knowledge institutes Deltares NIOZ Beroepsvissers Zuid-west Nederland Sportvissers Zuid-west Nederland Nederlandse Vissersbond Fishing Nederlandse Oestervereniging Vereniging Mosselhangcultuur Producentenorganisatie Mosselcultuur Toeristisch Ondernemend Zeeland Natuur- en Recreatieschap De Grevelingen RECRON Recreation & tourism Nederlandse Onderwatersport Bond Nederlands Watersportverbond Entrepreneurial associations of the municipalities Shipping Koninklijke Schuttevaer Inhabitants Individuals

Figure A3 Nature management map 2019 (Adapted from Provincie Zeeland, 2019). Working areas of nature managers in the Province of Zeeland. The Eastern Scheldt and Lake Grevelingen are national waters, therefore they are managed by Rijkswaterstaat. However the shoreline’s nature and islands are managed by the organisations shown in the map.

Appendix 6: Results and status of WFD quality elements of research areas In order to determine the status of the research areas, monitoring was performed by Rijkswaterstaat (Witteveen+Bos, et al., 2018a). The monitoring data is provided and compared to the scales of the WFD. Consequently the status of the water bodies in concluded per (sub) quality element. The overall biological and chemical status is concluded. In this chapter, an overview of all monitoring results and final results of the WFD quality elements are provided per research area.

Appendix 3 provides an overview with the scales for the natural water types (Van der Molen, et al., 2012). However the Eastern Scheldt and Lake Grevelingen are heavily modified water bodies (Rijkswaterstaat, 2018). The Eastern Scheldt is resembled by type K2 and Lake Grevelingen is resembled by type M32 (Ministerie van Infrastructuur en Milieu, 2015). Some scales of the biological (sub) quality elements are altered to the specific water bodies (Rijkswaterstaat, 2019a). In order to clarify the resemblance of the scales per (sub) quality element with the natural water type or the new scale, the GEP is provided. The conclusion of the status per (sub) quality element is made by the colour indication, as shown in Table 1. The status of a category (biology, physical chemistry, etc.) is corresponding with the quality element of the lowest score (one-out-all-out principle). The status of the overall ecology and chemistry is corresponding with the category of the lowest score.

In order to conclude the status of the (sub) quality element, two types of results are shown for different years. For biology, the ‘monitoring result’ is the EQR score calculated from measurement results of each sub quality element of the monitoring year, which results in the EQR score per quality element. The monitoring results are reported in Rijkswaterstaat’s database (MWTL Basisrapportage, 2019b). The method for monitoring and assessment is set by the WFD to ensure the quality of monitoring and to enable comparison of water bodies in the EU. Member States are obliged to monitor the (sub) quality elements once every six years (Ohm, Ten Hulscher, & Smits, 2014). However a ‘final result’ is given for the status of all quality elements and categories every year. The ‘final results’ for the years 2009 and 2015 until 2019 are reported by Rijkswaterstaat (Totaal eindoordeel met biologie - ecologie - chemie, 2019a). The ‘final result’ is the mean EQR score of the last three monitoring years (Ohm, et al., 2014). For this reason, a ‘final result’ of a particular year can differ from the ‘monitoring result’ of that same year. For physical chemistry elements, monitoring is performed ever year, for which the ‘final results’ are given (Rijkswaterstaat, 2019b). For pollutants and ubiquitous substances, the ‘monitoring result’ is used. Both types of (available) results are shown in this Appendix.

The monitoring results are reported in Rijkswaterstaat’s database (MWTL Basisrapportage, 2019b). Monitoring is not performed every year (N.A.). In some years monitoring was performed, however the EQR score is unknown (?). The ‘final results’ for the years 2009 and 2015 until 2019 are reported by Rijkswaterstaat (Totaal eindoordeel met biologie - ecologie - chemie, 2019a). The conclusion of the status per (sub) quality element is made by the colour indication, as shown in Table 1. The status of a category (biology, physical chemistry, etc.) is corresponding with the quality element of the lowest score. The status of the overall ecology and chemistry is corresponding with category of the lowest score. In the following, all available information is collected in order to conclude the status of the Eastern Scheldt and Lake Grevelingen.

A6.1 Eastern Scheldt A6.1.1 Physical chemistry

Quality element Sub quality element GEP Final result Final result Final result Final result Final result 2009 2015 2016 2017 2018 Thermal conditions Daily value (Celcius) ≤ 25 19,2 20,9 19,7 20,8 20,1 Oxygen balance Saturation (%) ≥ 60 98,6 100 99,6 98,2 93 Nutrients Winter DIN (mgN /l) ≤ 0,46 0,49 0,54 0,52 0,51 0,43

A6.1.2 Priority substances Substance AA-EQS inland MAC-EQS inland Monitoring result Monitoring result Monitoring result surface waters surface waters 2016 2017 2018 Arsenic, dissolved (µg/l) 0,5 8 ? ? ? Silver, dissolved (µg/l) 0,01 0,01 N.A. ? ?

A6.1.3 Ubiquitous substances

Substance MAC-EQS inland MAC Biota Monitoring result Monitoring result Monitoring result surface waters 2016 2017 2018 Benzo(ghi)perylene 8,2 × 10-3 (µg/l) N.A. 4,4 (µg/l) 1,8 (µg/l) 1,7 ( µg/l) Mercury 0,07 (µg/l) 20 (µg/kg) 3,6 (µg/l) ? 4,6 (µg/l)

A6.1.4 Biology

Quality GEP Final Final Final Final Final Sub quality element Monitoring Monitoring Monitoring Monitoring Monitoring Monitoring element (EQR) result result result result result result (2009) result (2010- result (2013) result (2014) result (2015) result (2016) 2009 2015 2016 2017 2018 (EQR) 2012) (EQR) (EQR) (EQR) (EQR) (EQR) (EQR) (EQR) (EQR) (EQR) (EQR) Phaeocystis blooming ? ? ? 0,870 0,944 0,58 Phyto- frequency (%) 0,6 0,74 0,91 0,91 0,89 0,86 ? ? ? 0,935 0,947 0,77 plankton Chlorofyl-a (90-p; µg/l) ? ? ? 1,000 0,949 0,96 Salt marsh (% of total water body) 0,128 N.A. 0,112 N.A. N.A. 0,112 (schorren) Salt marsh quality 0,133 N.A. 0,3 N.A. N.A. 0,3 (credits) (schorren) Seagrass area (% of Other 0,011 N.A. 0,016 N.A. N.A. 0,015 aquatic 0,14 0,03 0,13 0,13 0,13 0,13 total water body) 0,102 N.A. 0,156 N.A. N.A. 0,135 flora Seagrass quality (% coverage dwarf 0,239 N.A. 0,362 N.A. N.A. 0,267 seagrass) Seagrass quality (% coverage common 0 N.A. 0 N.A. N.A. 0 seagrass) Polyhaline  Species 0,69 N.A. ? ? N.A. N.A. 0,45* Macro- richness (S) ^2012 fauna: Polyhaline  Benthic 0,65 0,6 0,70 0,64 0,64 0,64 0,64 Shannon Index (log2) N.A. N.A. ? ? 0,59 N.A. N.A. N.A. N.A. 0,58* 0,59* inverte- (H) ^2011 brate AMBI fauna N.A. ? 0,62 ? N.A. N.A. 0,74* ^2010 * (Verduin, Leewis, & Van Haaren, 2018)

A6.2 Lake Grevelingen A6.2.1 Physical chemistry Quality element Sub quality element GEP Final result Final result Final result Final result Final result 2009 2015 2016 2017 2018 Thermal conditions Daily value (Celcius) ≤ 25 20,8 22,1 21,2 21,6 21,9 Salinity Chlorinity (mg C /l) ≥ 10000 N.A. ? ? ? N.A. Acidity pH 6,5 – 9,0 8,2 7,7 7,73 8,6 7,92 Oxygen balance Saturation (%) 60 - 120 106 102 101 102 102 Nutrients Winter DIN (mgN /l) ≤ 0,46 0,33 0,46 0,46 0,47 0,39 Transparency SD (m) ≥ 0,9 2,14 2,1 2,1 2,2 2,1

A6.2.2 Priority substances Substance AA-EQS inland MAC-EQS inland Monitoring result Monitoring result Monitoring result surface waters surface waters 2016 2017 2018 Arsenic, dissolved (µg/l) 0,5 8 1,5 1,9 1,0 Silver, dissolved (µg/l) 0,01 0,01 N.A. ? ?

A6.2.3 Ubiquitous substances Substance MAC-EQS inland MAC Biota Monitoring result Monitoring result Monitoring result surface waters 2016 2017 2018 Benzo(ghi)perylene 8,2 × 10-3 (µg/l) N.A. 1,5 (µg/l) 1,5 (µg/l) 1,5 (µg/l) Mercury 0,07 (µg/l) 20 (µg/kg) ? ? 2,1 (µg/l)

A6.2.4 Biology

Quality GEP Final Final Final Final Final Sub quality element Monitoring Monitoring Monitoring Monitoring Monitoring Monitoring Monitoring element (EQR) result result result result result result (2009) result (2010- result (2013) result (2014) result (2015) result (2016) result (2017) 2009 2015 2016 2017 2018 (EQR) 2012) (EQR) (EQR) (EQR) (EQR) (EQR) (EQR) (EQR) (EQR) (EQR) (EQR) (EQR) Phaeocystis blooming ? ? ? 1,000 1,000 1,00 N.A. Phyto- frequency (%) 0,6 0,92 0,86 0,88 0,82 0,84 ? ? ? 0,986 0,687 0,82 N.A. plankton Chlorofyl-a ? (90-p; µg/l) ? ? 0,986 0,687 0,82 N.A. Seagrass quantity (% surface area with N.A. N.A. 0 N.A. N.A. N.A. 0 Other possible coverage) aquatic 0,01 0,01 0,00 0,00 0,00 0,00 Seagrass quality (% N.A. N.A. 0 N.A. N.A. N.A. 0 flora surface area of N.A. N.A. 0 N.A. N.A. N.A. 0 seagrass field with coverage > 60%) Macro- Species richness (S) ? ? ? N.A. N.A. 0,63* N.A. fauna: Shannon Index (log2) Benthic ? ? 0,55 ? N.A. N.A. 0,67* N.A. 0,6 0,55 0,58 0,58 0,58 0,58 (H) 0,51 0,67 N.A. N.A. 0,60* N.A. inverte- ^2010 AMBI brate ? ? ? N.A. N.A. 0,51* N.A. fauna CA** (amount of N.A. 0 0,4 N.A. N.A. N.A. 0,2 species ER** (amount of species) N.A. 0,8 0,6 N.A. N.A. N.A. 0,8 MJ** + MS** (amount of species) N.A. 0,333 0,4 N.A. N.A. N.A. 0,533 Fish Z1** + Z2** (amount 0,392 0,59 0,41 0,42 0,42 0,42 0,43 N.A. N.A. 0 0 0,439 N.A. N.A. N.A. N.A. N.A. N.A. 0 0,446 fauna of species) ^2011 CA** (biomass %) N.A. 0 0,109 N.A. N.A. N.A. 0,033 ER** (biomass %) N.A. 1 1 N.A. N.A. N.A. 1 MJ** + MS** 1 N.A. 1 1 N.A. N.A. N.A. (biomass %) Z1** + Z2** (biomass 0 N.A. 0 0 N.A. N.A. N.A. %) * (Verduin, Leewis, & Van Haaren, 2018) ** CA: Diadromous species; ER: Estuarine residents; MJ: Marine juveniles; MS: Marine seasonal quests; Z1: Fresh-water species, choride-tolerance ≤ 8 g/l; Z2: Fresh-water species, chloride-tolerance ≤ 4 g/l

Appendix 7: Overview of WFD measures Below, an overview of measures located in the Eastern Scheldt and Lake Grevelingen from all cycles of the WFD is provided. All measures are included in the RBMP(s) and information is retrieved from Rijkswaterstaat’s factsheets (2018). The measures from the first cycle have been executed. The measures from the second cycle are in development. Measures from the third cycle are planned.

Cycle Location Measure Initiator Additional information 1st Eastern Scheldt Recovery of tidal action Rijkswaterstaat In combination with measure Defence of and fresh-salt transition the edges of salt marshes and construction at Rammegors and of shellfish banks. Schelphoek Pilot: planting seagrass Rijkswaterstaat Execution of active vegetation management and water quality management. Pilot into the reintroduction of seagrass. Defence of the edges of Rijkswaterstaat In combination with measure Recovery of salt marshes and tidal action and fresh-salt transition at construction of shellfish Rammegors and Schelphoek. banks Creation of fishways at Water board Creation of five fishways from infrastructural works infrastructural works to polders. Lake Grevelingen Commisioning of Rijkswaterstaat Flakkeese Spuisluis forms a sluice between Flakkeese Spuisluis the Eastern Scheldt and Lake Grevelingen, in order to improve Lake Grevelingen’s water quality. Pilot: planting seagrass Rijkswaterstaat Execution of active vegetation management and water quality management. Pilot into the reintroduction of seagrass. 2nd Eastern Scheldt Research into Rijkswaterstaat Execution of research into derivation of pollutants exceeding pollutants and possible measures against the norms discharges, emissions and loss. Lake Grevelingen Commisioning of Rijkswaterstaat Currently, a tidal test center is in Flakkeese Spuisluis construction at the sluice. Pilot: planting seagrass Rijkswaterstaat Execution of active vegetation management and water quality management. Pilot into the reintroduction of seagrass. Research into Rijkswaterstaat Execution of research into derivation of pollutants exceeding pollutants and possible measures against the norms discharges, emissions and loss. 3rd Eastern Scheldt Cofinancing fishways to Water board Creation of five fishways from polders infrastructural works to polders.

Appendix 8: Consultation In this chapter a list of consultants is provided. The consultants are used as sources where documented sources are lacking or require more in-depth explanation. Furthermore, personal visions on the research topic are asked.

An overview is provided per topic of information provided by the consultants. The questions (Q) asked are stated and the answers (A) given are translated and summarized. The questions are numbered for reference, but are not ordered chronologically. The date for the information provided is added to the answers given to each question.

The following persons are consulted:

 Thijs Poortvliet (Rijkswaterstaat Zee & Delta): Reflection on research results; supplier contact persons; consultant on topics WFD and measures.  Alexander Nefs (Rijkswaterstaat District Noord): Reflection on research results; consultant topic Lake Grevelingen.  Eric van Zanten (Rijkswaterstaat Zee & Delta): Consultant on topics Eastern Scheldt, sand hunger and shellfish reefs.  Jan Willem Slager (Rijkswaterstaat Zee & Delta): Consultant on topic N2000.  Loes de Jong (Rijkswaterstaat Zee & Delta) Consultant on topic project Getij Grevelingen.  Marjoke Muller (Rijkswaterstaat Water, Verkeer en Leefomgeving): Consultant on topic WFD.  Willem van Loon (Rijkswaterstaat Water, Verkeer en Leefomgeving): Consultant on topic WFD quality element macrofauna.  Dick de Jong (formerly Rijkswaterstaat Zee & Delta): Reflection on research results; consultant on topics WFD, ecology, Eastern Scheldt and Lake Grevelingen.  Kees van der Vlugt (Foundation Het Zeeuwse Landschap): Consultant on topics Eastern Scheldt and activities Het Zeeuwse Landschap.  Tjeerd Bouma (NIOZ): Consultant on topics Eastern Scheldt, Lake Grevelingen, Building with nature and defence of salt marshes, tidal flats and activities NIOZ.  Frans van Zijderveld (Association Natuurmonumenten): Consultant on topics Eastern Scheldt and activities Natuurmonumenten.  Marijn Tangelder (Wageningen Marine Research): Consultant on topics ecology, Eastern Scheldt, Lake Grevelingen and activities Wageningen Marine Research.  Wilco Jacobusse (Foundation Nationaal Park Oosterschelde): Consultant on topics Eastern Scheldt and activities Nationaal Park Oosterschelde.  Jildou Schotanus (HZ University of Applied Sciences): Consultant on topic project Meer waarde met Mosselen. A8.1 Eastern Scheldt Q1: What are ecological issues at the Eastern Scheldt? What measures can be taken? Do these measures contribute to the WFD and N2000 goals? A1a: In the Eastern Scheldt, sand hunger forms the main pressure on ecology. The intertidal areas become lower and smaller, decreasing the foraging time and space for birds like stilts. Furthermore the aging of schorren (salt marshes located at dikes that allow vegetation) is an issue. The salt marshes become rough terrain with little birds and other animals. A solution could be excavation of the areas. Over time, the salt marshes will develop themselves, since sediment builds up again. This is how salt marshes can rejuvenate. This process serves the WFD goals, since salt marshes are part of the WFD quality elements. The seven-island plan serves the goals of N2000, in combination with aquatic nature, a link to the WFD goals could be made. Phytoplankton is restricted from multiplying

87 to a greater level, since shellfish consume phytoplankton. As long as the shellfish population is not decreased, phytoplankton cannot develop itself to a larger scale. The main topics for the WFD at the Eastern Scheldt are seagrass and salt marshes. – Dick de Jong, 28-3-2019 A1b: The biggest problem at the Eastern Scheldt is sand hunger. Furthermore, the Eastern Scheldt is a large production area that raises contradictions in use of space, since the maximum production capacity is exceeded. In addition, the required rest for foraging and breeding birds is pressured by recreational activities. – Kees van der Vlugt, 4-4-2019 A1c: The Eastern Scheldt is pressured by its activities. The area is ‘overused’, causing disturbance for birds. Measures for the prevention of disturbance of birds will be included in the new N2000 management plans. Furthermore, the aquatic nature could be better protected if multiple areas were categorized separately. Currently, the Eastern Scheldt is defined as a ‘Large bay’, however by categorizing smaller (strong ecological) areas, the protection of aquatic nature can be adapted to more specific circumstances. – Frans van Zijderveld, 12-4-2019 A1d: The Eastern Scheldt’s ecosystem has experienced multiple changes since the realization of the Delta Works. Firstly, the choice to keep the Eastern Scheldt ‘open’ was made considering the benefits for the shellfish industry. Both natural and cultured shellfish are an important factor in the Eastern Scheldt’s ecosystems. The Japanese oyster was introduced to boost the oyster growth, however the species grew faster than expected. The Japanese oyster filters algae, forming an important factor in the food chain. Currently, the Japanese oyster is decreasing due to viruses. Besides the Japanese oyster, other exotics affect the Eastern Scheldt’s ecosystem as well. It is researched that oyster reefs can successfully prevent erosion of intertidal areas and support sedimentation. See Q33. Secondly, the fish stocks are decreasing due to unknown reasons. To conclude, the three most important issues at the Eastern Scheldt are shifting management, sand hunger and oysters. – Marijn Tangelder, 18-4- 2019

Q2: Organisation Nationaal Park Oosterschelde is responsible for the functioning of the National Park and the detection of issues and put them on the agenda. What does this mean? A2: The functioning of the National Park means the goals of the park are met. The goals include (quoted (and translated) from Contournotitie meerjarenagenda Nationaal Park Oosterschelde; eindconcept 2018): 1. Protection and development of nature and landscape (intensifying nature management and nature development); 2. Strongly stimulation of education and information / comunication; 3. Stimulation of nature-focused recreation; 4. Promotion of research. Especially the goal of research can be expanded more. The organisation acts as the ‘guard’ of the Eastern Scheldt. The organisation detects or is informed of issues and then makes aware the suitable (management) organisation. For example, the organisation was (one of the) inititator in processes regarding sandhunger, trawl fishing and allocation of wind mills. – Wilco Jacobusse, 7-5-2019 A8.2 Lake Grevelingen Q3: What are main ecological issues at Lake Grevelingen? What measures can be taken? Do these measures contribute to the WFD and N2000 goals? A3a: For Lake Grevelingen, the reintroduction of seagrass and provision of oxygen are the most important steps of the improvement of the ecological water system, which might be realized in approximately ten years. As a result of the tidal action, the shores of the islands in and around Lake Grevelingen will erode. The shore (or bank) defences will become unstable. The intertidal areas at the shores are unsuitable for shellfish as defence. Furthermore, stilts use the intertidal areas. An option could be to research the possibilities for shore-defences. Another option could be to monitor the new situation for approximately ten years before making any decisions. Heightening the islands will only do more harm than good, since orchids grow on the shores. – Dick de Jong, 28-3-2019 A3b: After the realization of the Delta Works, Lake Grevelingen became brackish, however the aim

88 was to keep the lake saline. Therefore the Brouwerssluis was made. In the beginning, the sluice closed in winter. Then the decision was made to open the sluice permanently. These shifts in management have affected Lake Grevelingen’s (eco)system. Lake Grevelingen has more going on than just oxygen deficiency. It is a natural process for benthos to decrease as the Lake becomes deeper. The deeper areas contain less food. Thus, oxygen deficiency is not the only reason for the decrease in benthos. Currently, it is being researched that benthos are also decreasing in shallower parts of the lake. Interesting research into oxygen levels show that after the Brouwerssluis was opened permanently, the oxygen deficiency in the middle of lake increased. Improvement only occurred near the sluice. After the realization of the sluice, it was decided that the sluice would be closed in summer to prevent stratification. Questions could be asked why the sluice was still opened permanently. Furthermore, WMR is not executing pilots or measures at the moment, however the systems changes and their causes are researched. The fish stocks are not monitored very often, however this should be monitored annually to make conclusions on trends. The Flakkeese Spuisluis is expected to have a positive effect on fish stocks at Lake Grevelingen. An experiment concerning biological monitoring at the Flakkeese Spuisluis involved the placement of baskets containing mussels on both sides of the sluice (Eastern Scheldt and Lake Grevelingen). Mussels are a good indicator for water quality. Results have shown that the mussels on the bottom of the water bodies did not survive before the sluice was opened. After the opening the sluice, the survival of mussels improved. Furthermore, scenarios are being developed for Lake Grevelingen with and without tidal action. To conclude, the concentration of Tributyltin used to exceed the standards. Tributyltin is used in paint for (recreational) boats. Questions could be raised how the substance influences the ecosystems. For example, the substance could have influence on the (bad) development of seagrass. – Marijn Tangelder, 18-4-2019 A8.3 WFD Q4: How is a project submitted as WFD measure? A4: An overview of initiatives is made by regional departments including the implementation plan and costs, which is submitted to the European Union. - Thijs Poortvliet, 12-3-2019

Q5: How accurate are the WFD monitoring results? A5a: The method for monitoring is established by the EU for all water bodies, meaning the method is not specifically altered for each area, so monitoring results of different areas can be compared to each other. However in practise, the status can go beyond the WFD indicators. For example, the oxygen balance for Lake Grevelingen is assessed of ‘good status’, which is measured at a depth of one meter below water surface according to the WFD monitoring method. Lake Grevelingen however is facing oxygen deficiency in the deeper water layers, which is not monitored according to the WFD method. - Thijs Poortvliet, 12-3-2019 A5b: The monitoring results can be inaccurate, since monitoring is only obliged every six years. Furthermore, the set monitoring method can be adapted to the situation of a water body and the available (financial and material) means of a country. – Dick de Jong, 28-3-2019 A5c: The assessment of the status of a quality element is sometimes adapted by consultation of an expert. – Thijs Poortvliet 28-3-2019

Q6: How is the score for a whole water body determined when there are multiple monitoring locations per water body? Is the mean calculated? A6: The average EQR score for each monitoring location is calculated. Then the mean is calculated, which forms the EQR score for the whole water body. Marjoke Muller, 11-4-2019

Q7: Is monitoring of every (sub) quality element performed every year? A7a: Monitoring is not necessarily performed every year. – Marjoke Muller 15-3-2019

A7b: Biological quality elements are not measured every year, since the monitoring method is expensive. Monitoring is often performed every three years or every six years. – Thijs Poortvliet, 12- 3-2019 A7c: Additionally: When monitoring is only performed once every three years (or even once every six years), it is difficult to determine trends. Marjoke Muller, 11-4-2019

Q8: How is the status of each water body concluded per year, when monitoring is not performed every year? A8a: The final result or judgement for a year per quality element is a mean over the last three monitoring years, which is not necessarily the same year or the year before. – Marjoke Muller, 15-3- 2019 A8b: Additionally: the final judgement is assessed by an expert, possibly adapted. – Thijs Poortvliet, 15-3-2019

Q9: Why is the mean over the last three monitoring years used? A9: By using the mean, natural variations per year are filtered. For example, extreme temperatures only occurring in one year can influence the score, providing inaccurate trends. – Marjoke Muller, 11- 4-2019

Q10: How much value is the WFD status assessment of water bodies worth? Aza: The results of the WFD assessment are of little value, since the method is set by the WFD. In practise, water bodies can require different methods of monitoring (see example Q5). Furthermore, the Dutch government does not look beyond the GEP, taking minimum effort, only to achieve the status that they are obliged to achieve. Measures to improve the status to a higher status than the GEP will not be taken. – Dick de Jong, 28-3-2019 A10b: The WFD is a tool to plan measures that improve ecology of water bodies and to achieve goals. Since the WFD is included in legislation, measures are only taken to achieve the effort-obligation. This forms a risk, since (improvement of) ecology goes beyond the WFD goals. – Marjoke Muller, 11- 4-2019

Q11: The WFD status is not allowed to deteriorate. What does this mean? A11: For biology, no deterioration is considered for the status of quality, meaning that quality elements phytoplankton, other aquatic flora, macrofauna and fish fauna may not deteriorate to another status in the scale. The status may not deteriorate from green to yellow, yellow to orange, orange to red. If the status is already bad (red), the EQR score may not decrease. For chemistry, the concentrations of pollutants may not increase. - Marjoke Muller, 11-4-2019

Q12: How are scales for heavily modified water bodies developed? A12: The scales of the heavily modified water bodies are the same as the scales for natural waters, however the goals are different. The goals exist of heavy modified water bodies are developed by exploring what status is achievable by taking measures. The goals are ambition-based. - Marjoke Muller, 11-4-2019

Q13: Why do the scales for heavy modified waters not include the ‘high status’ and the reference, like natural waters have? A13a: The Netherlands does not take effort to achieve a status above the GEP (see Q10). – Dick de Jong, 28-3-2019 A13b: The WFD has set the two different scales for natural waters and heavily modified waters. The high status for heavily modified water is not required. Marjoke Muller, 11-4-2019

Q14: How can the WFD goals be adapted? For example to a new situation like at Lake Grevelingen (water body type might shift from M32 to K2)? A14: The scales and goals can be altered to the situation of the water body or a new type of water body can be added to the WFD scales and references. The initiative for changing the water type and goals is with the manager of the water body, which is the regional department of Rijkswaterstaat. The national team can be consulted in the process, since it is a national procedure to change the type. After consultation at the RAO (Regionaal Ambtelijk Overleg) and RBO (Regionaal Bestuurlijk Overleg), the official change in water type can be processed in official documentations. Marjoke Muller, 11-4-2019

Q15: When is an initiative considered cost-effective? A15: A measure is assessed cost-effective when prioritising all submitted WFD measures. The cost- effectiveness is assessed by comparing measures to each other, while looking at the available budget. Then, the measures are prioritised. Marjoke Muller, 11-4-2019

Q16: When assessing WFD measures, are the effects on N2000 goals considered? A16: WFD measures often contribute positively to N2000 goals. During prioritising WFD measures, it is attempted to take account with N2000. ‘Free-ride’ opportunities with measures are considered. When a WFD measures has negative effects for N2000 goals, the decision on the implementation of the measures is dependent on the permit-granting authority. Negative effects need to be reported to the EU, including a motivation for the implementation of a measure, so a decision can be made. Marjoke Muller, 11-4-2019

Q17: What is measured to determine the sub quality elements of Species Richness, Shannon Index and AMBI, as part of the quality element macrofauna? A17: All species, the abundance per species per sample area. – Willem van Loon, 15-4-2019

Q18: To which species is the BEQI2-method applicable? A18: The method is particularly applicable to endo fauna and partly on epifauna. – Willem van Loon, 15-4-2019

Q19: Does the BEQI2 method provide a complete overview on the ecological status of macrofauna? A19: The BEQI2 provides a reasonably well overview, since the method involves three indicators. For a fully complete overview, the total biomass and eco-engineers (mussel- and oyster banks) should be included. – Willem van Loon, 15-4-2019

Q20: How do stakeholders take account with or involve the WFD during management or project plans? How do stakeholders take account with or involve aquatic nature during management or project plans? A20a: Het Zeeuwse Landschap manages multiple areas in and around the Eastern Scheldt. The organisation focusses mostly on ecology and not chemistry. Het Zeeuwse Landschap pleads for the inclusiveness of aquatic nature in projects, for example in production processes at the Eastern Scheldt. – Kees van der Vlugt, 4-4-2019 A20b: Currently, the importance of aquatic nature is growing, besides nature above the water surface. Opportunities to link projects to the WFD have been missed. – Frans van Zijderveld, 12-4- 2019 A20c: The WFD goals are taken into account when executing research at Wageningen Marine Research. For example, Bureau Waardenburg is developing WFD scenarios for Lake Grevelingen with or without tidal action, using calculations. – Marijn Tangelder, 18-4-2019

A8.4 N2000 Q21: For some conservation goals, the management plan shows that the goal can be achieved on the short term by taking measures, and on the long term the goal is achieved current management. Why are measures taken on the short term if on the long term the current management is sufficient? A21: It is assumed that on the long term, the measures of the short term are actually implemented. – Jan Willem Slager, 26-2-2019 A8.5 Tides Lake Grevelingen Q22: Who wrote Werkplan 2019 Getij Grevelingen? A22: The work group Grevelingen (Werkverband Grevelingen). – Loes de Jong, 18-4-2019

Q23: What is the current status of the plan? What is involved in the decision of preference (voorkeursbesluit) that will be taken in the summer of 2019? A23a: The MIRT decision involves how the islands at Lake Grevelingen will be managed when tidal action is restored. Furthermore, the decision involves the choice for a tidal power station and the amount of tidal action that is brought back. – Tjeerd Bouma, 10-4-2019 A23b: The decision involves the scope of the alternative(s) of preference, the budget, financing and method for the next phase of plan development (planuitwerking). Specifically, the decision involves water level management (medium water level and tidal range), the type of sluice (cylinders, turbines or a combination), the climate robustness and method for mitigation or compensation of negative effects on usage functions and nature. Currently, the work group Grevelingen is working on the content required for the decision of preference. In November 2019, the decision will be presented to the Minister of Infrastructure and Water Management, who is the qualified authority for making the decision. The Minister makes the decision considering the advice of the Ministry of Agriculture, Nature and Food Quality, the Provinces of Zeeland and Zuid-Holland and the municipalities of Schouwen-Duiveland and Goeree-Overflakkee, since they contribute to the project financially. The Minister will receive the advices of the parties latest in October 2019 after their management activities have been discussed. – Loes de Jong, 19-4-2019

Q24: Why is the project part of the PAGW and not WFD, when it serves the goals of the WFD? Aa: PAGW looks beyond the goals of the WFD, since the water quality of water bodies might be pressured beyond the WFD goals or WFD monitoring methods (see example Q5). – Thijs Poortvliet 12-3-2019 A24b: The Netherlands has made a budget available for the implementation of the WFD. However, it turned out there is not enough budget for all measures when setting the programme of measures in 2005. During prioritizing, measures that were socially unacceptable due to high costs and/or measures of which the effectiveness could not be estimated beforehand were not included as WFD measures. The project Getij Grevelingen was not included due to its relative high costs. During intermediate evaluations there was no opportunity to adapt the prioritization of measures. The programme of measures was set until 2027 in 2005. – Loes de Jong, 18-4-2019

Q25: What are possible negative effects on N2000? Will these effects be compensated for? A25: The change in water system will make some of the current goals more feasible, like the diversity of species and habitats, saline habitats and stilts. The shift does not affect higher elevated fresh water habitattypes and plants like bushes (Struwelen). The current conservation goals for coastal breeding birds, Humid dune slacks and Fen orchid are more difficult to realize, due to little suitable habitats. Furthermore, the resting areas for stilts at the Eastern Scheldt are decreasing during high tides. Compensation method to mitigate or compensate negative effects are currently being researched. – Loes de Jong, 18-4-2019

Q26: Why is the status of Lake Grevelingen’s oxygen balance assessed of ‘good status’ according to the WFD? A26: see Q5. A8.6 Intertidal areas Q27: Can salt marshes be supplemented? A27: No, since vegetation grows on salt marshes, only tidal flats and sand banks can be supplemented. – Dick de Jong, 28-3-2019

Q28: What measures have been taken or are in progress to mitigate erosion of salt marshes? A28a: Currently, NIOZ is researching methods of schorverdediging (salt marsh defence). I believe that if we had the current knowledge back when ‘hard’ defences were used as defence on salt marshes, the defences would have been done differently. For example, by using pioneer vegetation and allowing it to expand. Protection methods of salt marshes could be improved by looking more at the whole system. One defence can protect the next, which serves the next and so on, until the whole area up to the dike is protected from pressures like erosion (‘cascades’). – Tjeerd Bouma, 10-4-2019 A28b: Firstly, experiments testing the ability of Common Cordgrass on tidal flats to create salt marshes have been conducted at the Eastern Scheldt. Results show that salt marshes can develop well with low wave impact. Parts of the vegetation was washed away by waved. Secondly, the introduction of tidal action at Rammegors is an interesting experiment, since it is tested how an area changes from a fresh water environment to a saline environment. Rammegors is a polder located in the Eastern Scheldt, where a sluice was made to allow salt water and tidal action into the area, aiming to create new salt marshes. The project is interesting for the WFD, since it is tested how much time a salt marsh needs to develop itself from a previously fresh water environment. The first phases show growth of Salt wort, then channels are formed and eventually salt marsh vegetation will develop. – Marijn Tangelder, 18-4-2019

Q29: Are all salt marshes provided with hard defences currently? What can still be done to make the WFD score sufficient (make areal bigger)? A29: Salt marshes are threatened by erosion (sandhunger) and sea level rise. In time, sea level rise forms the largest threat, salt marshes will eventually drown. Measures to make salt marshes grow do not exist. Only one salt marsh (located at the Grevelingendam) is growing due to sedimentation, even though the salt marsh is disturbed by people’s activities. Cordgrass fields could be planted on previous salt marsh ground in order to develop the salt marsh again. However the salt marsh did disappear for a reason, which might result in loss of the salt marsh again. Currently, the salt marshes of the Eastern Scheldt are very poorly defended (by using stones). Stones (or hard defences) are the best way to defend salt marshes. However the few salt marshes containing the hard defences are still eroding. The only way to achieve the WFD goals for salt marshes is to change the goal. – Eric van Zanten, 19-4-2019

Q30: What is the effect of sand hunger (loss of salt marshes and tidal flats) on macrofauna? Does sand supplementation mitigate the negative effects? A30: During sand supplementation, benthos is affected negatively, taking a long term to recover. By using the method of priming, in which the sediment layer containing benthos, is moved. This way the benthos requires less time to recover after supplementation. – Tjeerd Bouma, 10-4-2019 A8.7 Seagrass Q31: Will the WFD measure continue in the 3rd cycle of the WFD? A31: This is dependent on the availability of financial means. The seagrass project is on the (national)

93 list for WFD measures in the 3rd cycle, however at the bottom of list of prioritization. Therefore it is currently unsure whether the project will continue in the 3rd cycle. – Thijs Poortvliet, 4-4-2019

Q32: How can seagrass be implemented at the Eastern Scheldt and Lake Grevelingen to serve the WFD goals? A32: At the Eastern Scheldt, research has been conducted to test if seagrass can survive behind the oyster reefs. The results show bad survival of seagrass. Experiments to develop seagrass often go wrong. Understanding of (eco)systems needs to be improved in order to succeed the experiments. It is that seagrass was doing well before, and has (almost) disappeared. The reason for the decrease needs to be known in order to reintroduce seagrass effectively. Furthermore, the concentration of Tributyltin used to exceed the standards. Tributyltin is used in paint for (recreational) boats. Questions could be raised how the substance influences the ecosystems. For example, the substance could have influence on the (bad) development of seagrass. More knowledge is required on the factors that influence seagrass growth. – Marijn Tangelder, 18-4-2019 A8.8 Shellfish reefs Q33: Can shellfish reefs contribute to the defence of salt marshes? A33a: Mussels and oysters reefs could contribute if they are located on the lower parts of the salt marshes. The higher (elevated) the shellfish are, the less time they have to feed, which happens in the water. The same principle accounts for vegetation on salt marshes, the longer the vegetation is under water, the more likely the vegetation will die. – Tjeerd Bouma, 10-4-2019 A33b: The Building with Nature programme uses Japanese oysters to prevent erosion of tidal flats and to support sedimentation behind the oyster reefs. An experiment was done at the Slikken van Viane, near Zierikzee, in order to test if the effects of waves on the oyster reefs. Furthermore, it was confirmed that the Japanese oyster can settle themselves after placement of the reefs and grow naturally. For salt marshes, it is researched that a cascade system could be used for protection, where one defence measure protects the next. – Marijn Tangelder, 18-4-2019

Q34: What is the status of the project involving mussel banks at Viane? A34a: The project is called More value with mussels (Meerwaarde met mosselen). In the designation decree of N2000 is stated that mussel banks require improvement at the Eastern Scheldt. In the past, mussel banks could be found at the tidal flats at Viane (Slikken van Viane). Until the 1990’s, mussel growers located mussels on sand banks (that fall dry). However birds foraged from the mussel banks, therefore the mussel growth shifted to the water. The project involves a research into how mussel growth can be developed, performed by HZ and NIOZ. Subsidy is provided by RAAK-PRO. Experiments were performed using different method to test how mussels can develop. The best method involved a mobile fences, on which mussels are put. The mussels attach themselves to the fences. After a storm, the mussels started rolling, however the banks remained attached to the fences. Reports on the project will be developed in 2019. The project has already resulted in a technique that develop living mussels. The goal of the project is to improve the mussel banks in order to contribute to the N2000 goal and to test the feasibility of growing mussels on intertidal areas. Upscaling would be possible, however a good motivation is required. – Eric van Zanten, 19-4-2019 A34b: The project More value with mussels focusses on the method creating mussel banks on intertidal areas, in order to serve the shellfish industry, stabilize intertidal areas for sandhunger and create natural values. The project is part of the N2000 goals. The mussels (seeds) are placed at tidal flats that are most affected by erosion and wave impact. The implementation of the project started three years ago at the tidal flats of Viane. MZI (Mosselzaad-Invanginstallaties) seeds are used on eroding parts of the tidal flats, which have to settle and develop. Sufficient amount of seeds need to be planted, since mussels take time to develop to predation (e.g. from crabs and birds). The first

94 result involve the successful method to create sustainable mussel banks (at Viane). Additionally, the musel banks trap sediment. Results for the mussel banks’ contribution to biodiversity are not finished yet. Birds species are monitored daily by taking photos every 15 minutes. The Oystercatcher benefits from the mussels. This summer, macrofauna will be monitored upcoming summer, to see the difference from one year ago. One year is a short time to see the development. The project involves mussels (and not oysters), since the Eastern Scheldt has a sufficient amount of oyster reefs. Mussel banks on tidal flats decreased after the construction of the Delta Works. Furthermore, mussels have a different function in the ecosystem, for example, birds can forage on them. Additionally, there is a demand for mussels from the shellfish industry. The combination of mussel fishing while maintaining the mussel banks for its ecosystem services can be arranged via a management strategy. Another option for the benefit of mussel growers could be to only supply the mussel seed. The project will result in insight in the value of mussels for each stakeholder, which is currently in progress. The possibilities for upscaling the project are looked into, the Roggenplaat, Galgenplaat, Dortsman, Krabbenkreek and the North-side of the Oesterdam are considered in addition to the tidal flats of Viane. However upscaling is dependent on the availability of financial means and the results of the project. The WFD was not included in the plan. – Jildou Schotanus, 8-5- 2019 A8.9 Bird islands Q35: How could the project be linked or combined with a WFD measure? A35: The islands could be combined with the development of nature below the surface, by exploring the possibilities of aquatic nature. The project of Griend (located in the Wadden sea) could be used as an example. – Thijs Poortvliet, 12-3-2019

Q36: Could the project of the island Griend, where aquatic flora is combined with the islands, be implemented in combination with the bird islands? A36: It should be explored whether shell banks, seagrass could be combined with the bird islands. The bird islands are made of sand which does not affect aquatic nature negatively. The Wadden sea is of a different, much rougher, water type than Lake Grevelingen though. – Thijs Poortvliet, 13-3- 2019 A8.10 Seven-island-plan Q37: What is the current status of the plan? Will it be executed? By who? A37: Currently, project plans for the islands in the Western Scheldt are in production, since the situation concerning breeding locations for birds is the most urgent in the Western Scheldt. The seven islands will be created in phases, in order to create different stages for the islands. The different types of breeding birds require different types of breeding areas, which are created through the process of constructing the islands. Therefore, the islands will not be created simultaneously. It is already decided that initial project at the Roggeplaat will not be adapted to the seven-island-plan. The short-term measures described in the plan are included in the nature management that Het Zeeuwse Landschap executes at its (owned) areas. – Kees van der Vlugt, 4-4-2019

Q38: What could be effects on the WFD goals? Can the project be expanded to a WFD measure by combining islands with aquatic nature? A38a: Het Zeeuwse Landschap pleads for including aquatic nature management in project plans. The project plans for each specific island in the Eastern Scheldt are not finished yet. The combination with oyster banks and mussel banks could be made. – Kees van der Vlugt, 4-4-2019 A38b: Involving aquatic nature forms an opportunity for getting more financial means for a project. – Thijs Poortvliet, 4-4-2019

A8.11 Wadden mozaiek and Griend Q39: Are the (sub) projects of project Wadden mozaiek and Griend WFD measures? A39: No. – Thijs Poortvliet 12-3-2019

Q40: Which WFD and N2000 goals are served by the sub projects? A40: Aquatic flora, benthic fauna and fish fauna. Better quality and/or quantity of fish serves the N2000 goals for fish-eating birds. – Thijs Poortvliet 12-3-2019 A8.12 Ambitions Natuurmonumenten Q41 What ambitions or plans does Association Natuurmonumenten have at the Eastern Scheldt? Specifically at Roelshoek? A41a: Natuurmonumenten has financial means available for measures that form a response to sand hunger. There is an ongoing discussion whether it should be used for salt marshes or tidal flats. – Tjeerd Bouma, 10-4-2019 A41b: Currently, the importance of aquatic nature is growing, besides nature above the water surface. As mentioned in the Oosterscheldevisie, Natuurmonumenten is working on the allocation of an aquatic reserve (onderwaterreservaat). See Q42. Secondly, sand supplementation at the Roggeplaat will start in October 2019, as part of the Programmatische Aanpak Grotere Wateren (PAGW), the Galgeplaat is also taken account with for future supplementations. The combination with shellfish reefs is an opportunity. Thirdly, TenneT is constructing a new electricity route with power pylons in between Borssele and Rilland. One power pylon will be constructed in the Eastern Scheldt (near Krabbendijke). Since ecology will be affected by the pylon, Natuurmonumenten will receive financial compensation, which will be used for mitigating measures for sand hunger. Two areas near Zandkreek and the port at Neeltje Jans require dredging. Normally, the dredged sediment would be dumped into the deeper channels. However, the sediment can be re-used for mitigation measures. Currently, the type of soil is being researched by NIOZ. Results are expected in two weeks. If the sediment contains mud (slib), the sediment can be used to develop salt marshes. If the sediment contains sand, the sediment can be used for the supplementation of the tidal flat Hooghe Kraaijer. The planning is to start dredging in the autumn of 2020. Consequenctly, the design will be made and permits will be applied for. The oyster industry will be informed in the process. I expect no issues concerning the oyster sector. If the re-use of dredge-sediment proofs successful, the method might be repeated, since sandhunger keeps pressuring the Eastern Scheldt and more locations require dredging. In case the sediment can be used for the development of salt marshes, the project can be an opportunity for CO2 storage, since salt marshes can store CO2 (Blue Carbon project). Fourthly, the seven-island plan of Het Zeeuwse Landschap involves the Katseplaat, which is managed by Natuurmonumenten. The area can be used by coastal breeding birds. A combination with seagrass could be possible. – Frans van Zijderveld, 12-4-2019 A8.13 Ambitions Oosterscheldevisie Q42: What is the status of the research into a (onderwater) aquatic reserve at the Eastern Scheldt, as mentioned in the Oosterscheldevisie? A42a: Research is being conducted into an aquatic nature reserve. Het Zeeuwse Landschap argues that the reserve should be an actual reserve where nature is undisturbed. Other organisations argue that boats can still sail over it. A good location could be in the Kom (Eastern part) of the Eastern Scheldt or at the Verdronken stad van Reimerswaal. Another location could be at the Zeeland bridge, where sepias (zeekatten) are found. – Kees van der Vlugt, 4-4-2019 A42b: The purpose is not necessarily to protect species, but to assign an area where use is not allowed. The Eastern Scheldt is pressured by activities, the water body is over-used. For the aquatic reserve, it needs to be determined what activities are allowed. Both this and the location of the

96 aquatic reserve are discussed with the Province of Zeeland, Nationaal Park Oosterschelde and divers. Divers are involved, since they have the most knowledge of aquatic nature and suitable locations with valuable nature. The stakes of the shellfish industry have to be taken account with. Furthermore, the divers preferences are taken account with. For the location, all areas with hard substrate are considered. The Kom (Eastern part) is considered or near the Zeeland bridge. – Frans van Zijderveld, 12-4-2019 A42c: The reserve will have as little activity as possible, however the exact allowed activities are still being discussed. Goal is to create a nursery for the reserve and its surroundings. Although fishermen were initially against the plan, they can profit from the reserve, since the reserve contributes to a richer ecosystem. A richer ecosystem can provide more food for N2000 species. Furthermore, the reserve can serve as a communication tool, promoting the Eastern Scheldt’s ecology. The location has not been determined. The Plaat van Oude-Tonge, where seagrass is located, is not ruled out yet. During a session with experts the species the reserve should protect have been discussed and a decision still has to be made. This information is not published yet. It is not determined who will be the manager of the reserve. It is unsure if management activities are required, since it is not determined whether new nature will be created. Rijkswaterstaat is the manager of the Eastern Scheldt. Natuurmonumenten is actively involved in the process. The Province of Zeeland will be initiator of further decisions. It is important that stakeholders like the fishing industry and divers are involved from the start of the process. – Wilco Jacobusse, 7-5-2018 A8.14 Overall research Q43: What is your vision on the research objective? Are opportunities to link projects to each other and serve a wider goal missed in your experience? Are opportunities to link stakeholders’ projects and ambitions to the WFD and N2000 missed in your experience? A43a: Opportunities would be explored more easily if active management was arranged differently. The national government officially manages the national waters, however nature management is not included, raising a discussion. Currently, the (financial) means to facilitate experts is lacking. Experts need to actively look into pressures and opportunities of water bodies. The licensing authority (the Province) is lacking specific knowledge to make decisions. Nature management is transferred to nature organisations like Staatsbosbeheer and Natuurmonumenten. However aquatic nature (below the surface) does not have a manager in Lake Grevelingen, which should also be included in the active nature management. Furthermore, the task of the implementation of WFD measures should be transferred to the nature managers. In addition, active management includes looking ahead. The current frameworks (WFD and N2000) use the past as a guiding tool, since the status of water bodies is compared to the previous natural status. Furthermore, the WFD and N2000 should be included in the visions of all stakeholders when making plans. – Dick de Jong, 28-3-2019 A43b: Opportunities that can be linked to project are not considered enough. Systems are looked at separately, while systems can be supplementary. By performing experiments and learning from research, while developing measures for actual pressures. Research can start on the small scale and can be expanded after learning from its methods. Then it can become an opportunity to integrate it more into full systems. Rijkswaterstaat is doing well, looking at opportunities, learning from experiments and implementing what is necessary. However, opportunities should be discussed earlier in the execution stage. This way with limited effort, a project can have more value. – Tjeerd Bouma, 10-4-2019 A43c: Currently, the importance of aquatic nature is growing, besides nature above the water surface. Previously, opportunities to combine WFD, N2000 and sand hunger have been missed. – Frans van Zijderveld, 12-4-2019 A43d: WMR has the ambition to perform an intensive monitoring year. Monitoring includes the

97 chemical and ecological water quality, birds, production, zooplankton and other indicators of the ecosystem. When all indicators of a water body are performed in the same year, the monitoring results have more value. The understanding of water systems is vital to perform good management, which contributes to programmes like the WFD. – Marijn Tangelder, 18-4-2019 A43e: Using the context of project Getij Grevelingen: The project aims for improvement of the whole food chain by improving the water quality. Improved functioning of the food chain and water system have a positive effect on for example fish-eating birds and seals. Furthermore, tidal action will bring back intertidal areas, which will connect the water-connected food chain with the food chain of the islands and the Lake’s shores. This process can enrichen the current situation, however there it also involves a loss of habitat. The combination will hopefully add value either the WFD or N2000. – Loes de Jong, 18-4-2019