Ocean Sprawl

Abstract

Ocean sprawl is the proliferation of engineered artificial structures in coastal and offshore marine environments. These include ship hulls; infrastructure associated with land reclamation and urbanization (e.g., seawalls, bridges, floating docks); fisheries (artificial reefs, aquaculture installations); coastal defence structures (e.g., breakwaters, groynes); resource extraction (oil and gas rigs, renewable energy devices); and shipwrecks. Only fixed permanent and semipermanent structures are considered here and ship hulls are not included. Single structures can scale up with dramatic consequences for the local environment. Extreme examples of this include: the “New Great Wall” of China—seawalls enclosing coastal wetlands covering 60 percent of the total length of the Chinese coastline; “The World”, Dubai—an archipelago of over three hundred artificial islands constructed in the shape of a world map; and the “Steel Archipelago,” which describes more than four thousand oil and gas structures in the Gulf of Mexico. The placement of these fixed artificial structures modifies the local physical and chemical environment with cascading impacts on the composition, functioning, and service provision of surrounding species, habitats, and ecosystems. These structures also provide novel habitat which can offer surface for attachment, food, and protection for myriad marine species. They can act as fish aggregating devices, attracting fishing and other human activities. These structures may also have wide-reaching impacts through acting as barriers or conduits to ecological connectivity—the movement of organisms, materials, and energy between habitat units within seascapes. An improved understanding of the biological communities associated with artificial structures, coupled with the global drive for sustainable development, is driving an explosion of research into the design of multifunctional structures with built-in secondary ecological or socioeconomic benefits. Results to date have been promising but greater integration of the fields of ecology, engineering, and social sciences is necessary to better connect theory and practice in this emerging discipline.