Coastal transformation and marine habitat loss

Coastal areas are undergoing continuous transformation to sustain the increasing residential, commercial, and tourist activities. However, the proliferation of artificial infrastructures (i.e. marinas and breakwaters) may contribute to destroy and fragment marine natural habitats, to alter the connectivity among populations and, as a consequence, the natural seascape. In particular, the upper sub tidal rocky fringe, where the coastal transformations are more conspicuous, represents the natural habitat of dominant engineering algae, such as Cystoseira and Sargassum; some of them, because of their sensitivity to environmental variability, are considered biological elements of water quality. The recent attempt to measure historical changes in macro algal diversity in the Gulf of Naples has highlighted a dramatic decrease of Cystoseira species in the upper sub littoral zones and at the same time the lack of information on their up to date extension. To verify the influence of coastal development on the decline of Cystoseira species in the Gulf, the percentage of natural/artificial coastal length has been estimated with Google Earth orto-photos. The results testified a correspondence: the higher was the Cystoseira spp. loss, the greater was the development of artificial urban infrastructures. To follow the temporal dynamics of these shallow systems, a complete remonitoring of the fucoid distribution along the Neapolitan coast has been planned. Up to now, the occurrence of these species has been mapped and digitalized in a qGIS database (scale 1:2,500) for the shallowest fringe of the island of Ischia. An ongoing homogenization of diversity at a medium scale has been recorded: Cystoseira compressa (the less sensitive species) is the widespread species; fragmented stands of Cystoseira amentacea (the most sensitive) still exist. Their distribution is limited to natural habitats slope more gently while the highest diversity has been reached in rocky pools. Occasional settlements were recorded on artificial structures when natural marine habitat was preserved in the surrounding area and the distance among the algal patches could not be a limiting factor in the spreading of the species. These preliminary data seem to suggest that a stronger collaboration between engineers and ecologists could favour a better coastal management in order to mitigate the impacts of artificial infrastructures on natural marine ecosystems and avoid the loss of biodiversity.