Being responsible neighbours to marine ecosystems
Europe is home to miles and miles of beautiful coastline, especially in the Mediterranean region. Many settlements established in ancient times have since evolved into full-fledged metropolitan areas, complete with urban marine structures such as ports, marinas, seawalls and so on. To date, little work has been done to assess the impact of these structures on the marine ecosystem. This challenge was taken up by the 'Sustainable urban development: solutions to promote the biological and conservation value of marine urban structures' (Marurbe) project. Experiments were carried out to investigate the ability of beneficial marine algae, Cystoseira barbata, and an undesirable, invasive tunicate, better known as a sea squirt, to establish themselves. C. barbata populations are on the decline, but during Marurbe it was discovered that it could readily survive and reproduce on urban marine structures. In fact, structures with complex architecture may actually facilitate the growth of C. barbata. On the other hand, tunicates fare equally well on both naturally occurring and manmade reefs, though native species of sea squirts prefer the former. To complete the picture, the impact of the detritus of two of the most common inhabitants of urban marine structures, sea lettuce, Ulva spp., and the Mediterranean mussel, Mytilus galloprovincialis, was studied. Both types of detritus are deposited on the nearby seafloor, but their influence on the amount and types of macrofauna found therein is totally different. This finding emphasises the fact that urban marine structures must be carefully managed in order to control their influence on the marine ecosystem. Furthermore, the Marurbe results suggest that a site-specific approach should be developed and applied in order to obtain the best results.
