Impact of Urbanisation on Estuarine Sandflats: Use of Ecological Indicators, Stable Isotope Enrichment and Network Modelling

Abstract

Urbanisation often exerts large-scale adverse effects on coastal areas and estuaries, which are ecologically diverse and highly productive habitats. Understanding the ecological resilience of these habitats is a prerequisite for their management. Direct quantification of ecosystem functioning using conventional approaches, however, is difficult and time-consuming. This difficulty has greatly restricted ecosystem-level research and thus, the ability to predict an ecosystem’s responses to urbanisation. The main aim of this thesis was to assess the impact of urbanisation on estuarine sandflats. I developed a novel food web analytical approach, by combining stable isotope (13C) enrichment, compartmental modelling, and ecological network analysis techniques to quantify food web dynamics. This approach was tested with estuarine sandflats, which is one of the most important coastal habitats worldwide. The novel approach allows quantitative testing of specific hypotheses about food web dynamics through manipulative experiments, by comparing system indices that reflect ecosystem condition. Further, I conducted manipulative experiments using this approach to investigate the structural and functional response of a multi-level estuarine sandflat food web to two common anthropogenic stressors from urbanisation, namely, organic enrichment and physical disturbance.