Résumé : Coastal environments are exposed to anthropogenic activities such as frequent marine traffic and restructuring, i.e., addition, removal or replacing with man-made structures. Although maritime shipping and coastal infrastructures provide socio-economic benefits, they both cause varied perturbations to marine ecosystems. The ports and marinas receiving a high frequency of international vessels, act as ‘hot-spots’ for marine invasions. The disturbed and modified habitats found in harbours and ports provide opportunities for non-native species to settle due to their competitive traits. Once established, the non-native species may spread to neighbouring habitats, thereby modifying the adjacent natural environment, its biodiversity, ecosystem structure and functioning.
Up to 70% of coastlines around the world have now been modified and is expected to rise in future. New bioinvasions are still being reported even with various biosecurity and management approaches across the globe. It is essential to understand the potential factors influencing the bioinvasions to have effective biosecurity measures and management plans. The overall aim of this thesis is to determine the influence of man-made structures on the marine biodiversity and presumptive fitness of native and non-native species on these structures. This thesis investigates ports and harbours as man-made environments, their impacts on marine biodiversity and the species status – native, non-native and cryptogenic, and the factors facilitating the spread of non-native species.