The introduction of artificial structures on marine soft- and hard-bottoms: ecological implications of epibiota

摘要

Artificial structures, such as seawalls, breakwaters, jetties, pontoons and pier pilings are becoming ubiquitous features of landscape in shallow coastal waters of urbanized areas. Nonetheless, few published studies have focused on their ecology and little effort has been devoted to determine how the various objectives (economic, social and ecological) involved in their introduction into natural systems can be reconciled. These structures provide suitable substrata for a variety of epibenthic organisms, including macroalgae, invertebrates and fish (Bohnsack & Sutherland 1985; Connell & Glasby 1999; Davis et al. 2002; Bacchiocchi & Airoldi 2003; Chapman & Bulleri 2003; Bulleri & Chapman 2004). Since their primary objective is not to attract particular target species, there is, in general, no a priori expectation as to which assemblages should or should not become established on the new surfaces. The ecological value and implications for biodiversity of these epibenthic assemblages (at local and regional scales) depend on the type of natural habitat(s) mostly affected. Specifically, they will vary between the case in which artificial structures are deployed on hard-bottoms or soft-bottoms. Distinguishing between the two scenarios could, therefore, be key to avoiding the misinterpretation of the value of epibiota occurring on artificial structures by decision-makers and stakeholders.