Abstract
Beach ecosystems are subject to increasing pressures from the combined growing effects of coastal development and climate change, pressures that threaten the ecological health and resilience of beaches. Here we discuss the related concepts of ecosystem health and resilience in the context of sandy beaches and explore some salient consequences for shoreline management. Although concepts of ecological health vary, ecosystems have not evolved to an optimal stable state actively maintained by homeostatic mechanisms such as exist for individual organisms. Instead, ecosystems display great natural variability. Although this variability may be important for ecosystem health and evolutionary potential, the current poor knowledge of beach variability limits both ecological understanding and management. Similarly, the evolving concept of resilience is problematic for beaches but useful for management. Resilience encompasses different aspects of ecological stability (i.e., resistance to and recovery from disturbances) and internalises humans as part of the ecosystem. Fundamental to the understanding of both ecosystem health and resilience is knowledge of the natural state of a beach, its range of variability, appropriate experimental design (to isolate the effects of factors of interest) and the magnitude of change that constitutes a significant ecological impact. For both theoretical and empirical reasons, the last remains an uncomfortably subjective socio-scientific decision for coastal managers. Conceptual problems aside, the development of cost-effective protocols to assess beach health and resilience would be useful for coastal managers as would access to research findings and their scientific interpretation. Priorities include the establishment of a range of habitat and biotic response variables (both structures and processes), appropriate sampling methods and observational time series. Also needed are management strategies that enhance resilience. These should be ecosystem-based, internalise human activity, include a range of stakeholders, accommodate multiple stresses and operate at appropriate scales. The last recognises that beaches interact strongly with adjacent and distant systems. Strategies will be multi-faceted and include ecologically-benign, soft-engineering interventions (e.g. beach nourishment), allowing some beaches to migrate inland with rising seas, and providing refuges and corridors to enhance post-impact recovery. Ultimately, the maintenance of beaches as functional ecosystems, their ecological and social values and their ecosystem services will all require the acceptance of new paradigms for managing coastal population growth and climate change, these being fundamental underlying threats to beaches worldwide.