Urban coral reefs of East and Southeast Asia: A case study approach

Hard corals and coral reefs are common in many coastal cities in Asia. Understanding how urban coral reefs are structured and how they function is crucial for informing conservation. We compiled available data on hard coral... [ view full abstract ]

Hard corals and coral reefs are common in many coastal cities in Asia. Understanding how urban coral reefs are structured and how they function is crucial for informing conservation. We compiled available data on hard coral composition and abundance from four main case study cities (Singapore, Jakarta, Hong Kong, and Naha), as well as qualitative information from several additional coastal cities in East and Southeast Asia, with the aim of identifying unifying patterns of urban coral reefs and clarifying the effects of urbanization on hard coral assemblages. Through this case study approach, we highlight several key characteristics of urban coral reefs. “Reef compression” and (a decline in bathymetric range with increasing turbidity and decreasing water clarity), dominance by domed growth forms, and low reef complexity were common. Inshore-offshore gradients in urban coral reefs varied considerably between cities, but were strongest for the largest case study city considered, Jakarta. Declines in urban coral cover in the 20^th Century have been followed more recently by fluctuations from acute impacts and rapid recovery. We highlight the major urban-related stressors that likely shape these patterns and present hypotheses for urban reef community dynamics, which should be expanded upon and tested empirically in future research. Additionally, coral colonization of urban infrastructure was recorded in several cities, and constitutes an important component of restoration and enhancement efforts for coral reefs in urban areas. We discuss the potential for ecologically engineering urban shorelines to enhance ecosystem services provided by coral reefs to urban populations.