Abstract
Sandy beaches are impacted by multiple threats, leaving them vulnerable to superimposed pressures from global change. While the extent of beaches along coasts is vast, management resources are finite, which necessitates prioritisation of beaches for management action. Our aim was to modify an existing, globally applied cumulative-impacts mapping framework to make it applicable specifically to sandy beach ecosystems at fine spatial scales. We conducted an online survey prior to the VIth International Sandy Beaches Symposium 2012, allowing beach experts to score habitat-threat interactions with regards to: extent, frequency and functional impact of disturbances, resistance of the ecosystem to these disturbances, and the time taken for complete recovery following the disturbances. We also investigated the relative weighting of these 5 categories in the final threat score, as well as interactions among stressors. There were 65 complete responses from sandy beach experts worldwide. The average range in scores was 9.7 out of a possible maximum range of 10 (i.e., at least one expert rated each threat-habitat interaction to be 0 or 1, and another scored the same phenomenon, 9 or 10), and extent and frequency were the only criteria experts were confident to score. There were no consistent significant biases in the scores associated with the experts' stated experience and expertise, or geographic factors. We concluded that the large range in perceived threat intensities among experts, and potential misunderstanding of the tasks were the most likely explanations for the extreme variability in the scores. Since the response rate in the section on interactions among stressors was so low, we concluded that this was most likely because there is insufficient published information available for experts to evaluate threat interactions with any level of confidence. This was also confirmed by comments provided by experts in this section. In short, the methodology for assessing cumulative threats to beaches needs to be revised. The first aim of this workshop is thus to score the functional impact and recovery time of a base case scenario for each threat, which is represented by a realistic maximum intensity of the threat acting on a pristine beach. The second aim is to identify knowledge gaps and research priorities for threats to beaches. While the results from the online threats survey were too variable to be meaningful for their intended purpose, they have benchmarked our understanding of threats to beaches, and will be useful in guiding future research.