Assessment of coastal dune vulnerability to natural and anthropogenic disturbances along the Gulf of Mexico

Human population density is globally three times higher along the coasts than inland, and thus environmental impacts of human activities are greater in magnitude on coastal ecosystems such as beaches and dunes. Vulnerability assessment (the loss of capacity to return to the original dynamic state after system displacement) is thus necessary to evaluate the conservation status and determine the most relevant disturbance events. Twenty-six sites along 902 km of Gulf of Mexico coastline, varying in conservation status and sedimentary dynamics, were sampled. At each site a vulnerability index (VI) was calculated based on variables that described geomorphological condition, marine influence, aeolian influence, vegetation condition and human effects. Vulnerability was very variable along the coast and only 19% of the sampled locations (mostly in the central Gulf of Mexico) displayed low vulnerability. Cluster analyses of the values assigned to the checklists for each location grouped the studied sites into three, according to their VI values. Low vulnerability locations had abundant sediment supply and low human impact. Locations with medium to high VI were mostly affected by their natural geomorphological and marine features and had medium to intense human activities. Management strategies should consider the observed variability in vulnerability, the natural dynamics of these systems and the role of human activities and interests, in order to achieve adequate policies and establish well-informed priorities for integrated coastal zone management.