Urban structures as marine habitats

Large numbers of urban structures have been added to the waterways around c oastal cities and many more are likely to be added in the future. Some of t he most common structures seen in harbors around the world are pier pilings , pontoons, and retaining walls. These may be constructed from a variety of materials, many of which are foreign to the marine environment. Despite th e proliferation of urban structures around coastal cities, there has been s urprisingly little research on the effects they may have on marine biota. I n this paper we present details of studies which tested whether different t ypes of subtidal organisms grew on different urban structures and natural r ocky reefs. The results indicate that many urban structures in harbors and estuaries may be considered novel habitats, quite distinct from natural roc ky reefs. A great deal more research is needed to understand fully the cons equences of adding new habitats to the marine environment.