Ocean sprawl is the proliferation of human-made structures on the seafloor.
These structures include everything from seawalls to discarded garden statues.
Many of the structures that lead to ocean sprawl are not added to the marine environment with intentional, coordinated, or ecologically-oriented goals in mind, but are instead unintentionally discarded debris items. However, one’s trash is another’s treasure. Human-made structures of all kinds are colonized by benthic (bottom-dwelling) organisms. In many cases, the novel habitat provided by these structures supports communities of organisms that are not found in natural settings.
The same is true for structures associated with shoreline armoring, such as seawalls, breakwaters, and bulkheads. These structures are essential for urban infrastructure, flood defense, and city adaptation to sea level rise, yet they fundamentally change marine ecosystems.
Ocean sprawl is particularly expansive in sedimentary seascapes surrounding cities, where it creates a mosaic of hard- and soft-substrate habitat patches. Ecological theory tells us that it’s in these types environments (with high habitat heterogeneity) where we expect to see a lot of cross-habitat interactions between species and between ecosystems.