No abstract

No abstract

26Intertidal mussel beds are important for intertidal ecosystems, because they feature a high 27 taxonomic diversity and abundance of benthic organisms and are important foraging grounds 28 for many avian species. After the introduction of the Pacific oyster (Crassostrea gigas) into 29 the European Wadden Sea, many mussel beds developed into oyster dominated bivalve beds. 30Despite the fact that oysters have been colonizing many European intertidal areas for about 31 two decades, their impact on the ecosystem is still poorly understood. Here, we investigated 32 the impact of oysters on the condition of mussels and on the spatial distribution of birds on 18 33 bivalve beds with different grades of oyster occurrence throughout the Dutch Wadden Sea. 34Moreover, in comparing bird densities on bivalve beds with densities expected on the total 35 intertidal area, we could detect which species exhibit a preference for the structured habitat. 36Overall, 50 different bird species were observed on the beds, of which about half regularly 37 frequent intertidal flats. Most of these species showed a preference for bivalve beds. The 38 condition of mussels decreased with the oyster dominance, whereas the majority of bird 39 species was not affected by the oyster occurrence. However, three of the four species that 40 were negatively affected depend on intertidal mussels as food source. Even though the 41 Pacific oyster is a nonnative species, attempts to fight it may do more harm to avian 42 biodiversity than good.

No abstract

Long-term sustainable port development requires accounting for the intrinsic values of ecosystems. However, in practice, ecosystem considerations often only enter the planning and design process of ports when required by an Environmental Impact Assessment. At this late stage, most of the design is already fixed and opportunities to minimize and restore ecosystem impacts are limited. In this paper, we adopt a large-scale, ecosystem perspective on port development with the aim to identify ecosystem-based design alternatives earlier and throughout the planning and design of a port’s marine infrastructure. We present a framework, termed the ‘ecosystem-based port design hierarchy’ (EPDH), to identify ecosystem-based alternatives at four hierarchical design levels: 1) alternatives to port developments, 2) port site selection, 3) port layout design, and 4) design of structures and materials. In applying the EPDH framework retrospectively to a case study of port expansion in Tema, Ghana, we establish that ecosystem considerations played only a limited role in identifying and evaluating alternatives at all four design levels in the case study, whereas more eco-friendly alternatives in terms of port layouts, structures, and materials are identified using the EPDH framework. This reveals that opportunities for ecosystem-friendly port designs may have been missed and demonstrates the need for and the potential added value of our framework. The framework can assist practitioners in earlier and wider identification of ecosystem-based alternatives for a port’s marine infrastructure in future seaport developments and, hence, represents an important step towards more sustainable port designs.