Australian sandy-beach ecosystems and climate change: ecology and management

Abstract

Despite their great socio-economic importance, sandy beaches have attracted little ecological research. This is unfortunate since, contrary to popular belief, they support diverse ecological assemblages whose species are mostly small and buried and which deserve protection as part of ecologically sustainable development (ESD). Moreover, the management of beaches and linked adjacent ecosystems is becoming increasingly important because of their vulnerability to burgeoning human pressures including climate change. Although there are large uncertainties involved, some of the climate-related environmental changes and their ecological consequences for sandy beaches are explored in this paper, some management issues discussed and research proposed. Temperature-related changes include the likelihood that the geographical ranges of some species will change, some cool-adapted species will decline in abundance, possibly to extinction, and the rate of processes such as decomposition and photosynthesis will increase. The increasing acidification of the ocean may affect many beach species directly via reduced calcification and indirectly via changes to the phytoplankton on which some beach species depend for food. Changed hydrology may affect both nearshore primary productivity and the larval movements of many species. Increased storminess may change the morphodynamic state of beaches with consequent effects on the diversity, abundance and composition of beach assemblages.The combination of storm surges and sea-level rise may enhance erosion rates, the most extreme effect being the total loss of sandy beach habitat, especially if sea-walls are deployed to protect coastal assets. Alternatively, in some areas there may be a slow retreat of the coastline with few effects on beach ecosystems. Concerning management, both mitigation and adaptation strategies are needed to meet public ESD goals. The former would seek to constrain the increase in atmospheric greenhouse gases by addressing the underlying causes (i.e., population and economic growth) and by applying appropriate technologies. Adaptation strategies would recognise the linkages between beaches, dunes and surf zones and maintain sand movement and storage and allow for the landward migration of beaches. Failing this, the active maintenance of beaches in their present location by soft engineering (e.g., the transport of sand to the intertidal beach from elsewhere, a process called beach nourishment) is far preferable to hard engineering (e.g., sea-walls) from the nature conservation and socio-economic points of view. Since beach ecosystems are poorly understood even at basic descriptive levels, future management, monitoring, and predictions of the possible impacts of large-scale phenomena (such as global climate change) will be assisted by basic research into documenting biodiversity, community dynamics, autecology, and eco-physiology of beach fauna and the linkages with adjacent ecosystems. As well, the use of human interventions (e.g., beach nourishment) as scientific experiments combined with optimised monitoring is recommended.