The main objective of this thesis is to increase the understanding of the effect of shellfish presence on the stability of loose rock revetments and to investigate the possibilities in the design. Pacific oyster (Crassostrea gigas) and blue mussel (Mytilus edulis) presence on loose rock revetments was quantified. C. gigas and M. edulis are common shellfish species in the port area and act as ecosystem engineers. They require a certain salinity level, water temperature, phytoplankton ratio, and sufficient submersion time for daily feeding and respiration. The current presence of shellfish in the port area was predicted based on salinity levels generated by an OSR model. Outcomes were compared to qualitative measurements of C. gigas and M. edulis presence performed in the port area. C. gigas is present on revetments where salinity levels exceed 16‰, which is the case at Maasvlakte 2, Beerkanaal, and Calandkanaal. M. edulis were hardly observed in the port area on revetments. M. edulis can move relatively easily and detach from the surface after mortality occurs in contrast to C. gigas. They are, therefore, not considered a reliable structural addition, so only the effect from C. gigas was studied. C. gigas presence leads to binding of stones in revetments. This binding of stones will increase the stability of stones in the revetment. The relationship between the presence of oysters and stability upgrading is described using a connectivity model. The relationship between the presence of oysters and binding of stones is measured in the port area, these measurements are used to validate the model. Measurements showed that the cumulative coverage ratio of dead and living C. gigas decreases as one moves up to the intertidal zone from the mean low water level (MLW). The binding of stones increases when the coverage ratio of C. gigas is larger. This shows that there is a relationship between the coverage ratio of oysters and the binding of stones, and this assumes that there is a relationship between the coverage ratio of oysters and stability upgrading. The presence of oysters comes with structural, environmental, and ecological impacts. The conditions in the Port of Rotterdam as a system itself can pose various opportunities and threats for oyster coverage, such as global warming, pollution, and future port plans. Complementary measures can be implemented to mitigate the limitations and threats. The maintenance demand, and associated costs, decreases when oysters are present. Oysters are usually present naturally; their presence can be stimulated by enhancing C. gigas populations at locations with conditions that would allow potential oyster growth. Enhancement strategies depend on local conditions. Application is most promising when bow thruster or ship wave impact is normative because oysters are mainly found up to NAP +0.5 m. Additional enhancement costs are approximately equal to the expected reduction in maintenance costs. Possible ways of application in the Port of Rotterdam are summarized in a flowchart.

The aim of the Building with Nature (BwN) design philosophy is to improve on a traditional approach for infrastructural projects by utilising natural processes to create benefits for society and nature. In a fast-changing world where climate action is becoming increasingly important, there is need for an innovative approach in large infrastructural projects where nature is not considered as an obstacle, but stimulated and used in a sustainable way. The BwN design philosophy offers the opportunity to realize this improvement. This research first aimed to create an evaluation framework of (international) standards and goals to identify opportunities for improvement of a port masterplan and to get a better understanding of the need for sustainable port development. Included in this evaluation framework are, amongst others, the Port Vision2030, the Corporate Social Responsibility statement and the international strategy of the Port of Rotterdam (PoR). On the basis of these visions and standards, the corporate governance of the PoR was tested by conducting an informal opinion poll amongst twenty colleagues at the PoR (International, Environmental Management and Port Development). A practical example of a traditional port development project that can be improved by applying BwN is the Kuala Tanjung (KT) Port-Industrial complex at Sumatra, in Indonesia. This port development project is still in its initiation phase where a first master plan is proposed. Since the goal of the Indonesian government is to build a world-class port, international and sustainable standards apply. This project was used as a case to identify opportunities to improve a traditional master plan by applying a BwN approach. The evaluation framework was applied to the current master plan of KT to check whether this project meets the requirements for international port development, in particular from a nature/social point of view. It is concluded that the current design mainly focuses on the functional requirements of the port, proposing mitigation and compensation measures against the negative social and environmental impact of the port development. The BwN philosophy, on the other hand, prescribes a thorough understanding of the natural system emphasizing on the positive effects of the project for stakeholders and nature, to create a win-win solution. After applying the general evaluation framework, it became clear what aspects in the current master plan should be improved. A literature study of applied BwN solutions resulted in an onshore and offshore alternative for the port development including several BwN solutions. Together with experts involved in the KT project, it is concluded that the onshore alternative is more realistic (from a functional point of view), while still offering opportunities for applying the BwN philosophy. In the current natural system of KT the mangroves offer various important ecosystem services. In addition, it is concluded that the breakwaters proposed by the current master plan form a large part of the CAPEX. Consequently, a solution is proposed where mangroves are integrated in the design to attenuate waves and enhance nature at the same time. To test whether this BwN solution is realistic, a preliminary feasibility study has been executed. The results of a mangrove coastal protection program at Demak (Java, Indonesia) and various scientific articles (Ecoshape BwN Guidelines, 2018) about rehabilitation programs for mangroves have been used to set up a general checklist with habitat requirements for mangroves. These requirements were compared with the local conditions at KT and recommendations for creating these conditions at the breakwater location were given. According to the checklist, the site at KT appeared to be suitable for mangrove establishment. This resulted in preliminary mangrove breakwater designs for various depths. In addition, the effect of the BwN solution on the phasing of the adapted master plan was determined, rough cost estimates were made and the implementation risks were identified. According to these conditions, the mangrove-based breakwater appeared to be technically feasible for the first 2000 m of the shallow part of the south-eastern breakwater at KT. Finally, the evaluation framework was applied again to check if the current master plan of KT has been improved (read: less dilemmas occurring from deviating standards in Indonesia) and a general advice is given on the applicability of the selected BwN solution to other ports in Indonesia and (sub)tropical zones of the Asia Pacific region.