Visitor impacts and climatic variability will shape the future ecology of Fraser Island's perched dune lakes
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Fraser Island's perched dune lakes are magnets for tourists. Our research has documented the ecological consequences of unregulated visitor use of these systems, with a focus on the likely visitor-mediated delivery of nutrients to these oligotrophic systems. In addition to threats from visitors, a significant sleeper issue for perched dune lakes is climate change. Perched dune lakes are not connected to the regional water table and water levels are known to fl uctuate widely with local rainfall patterns. Given the projected changes in climate in the Fraser Island region - increased temperatures, reduced rainfall, increased evaporation and increased hydrologic variability - we anticipate that lake levels are likely to fluctuate even more in the future. These fluctuations are likely to have both ecological and infrastructure consequences. In this paper, we present a conceptual model of the natural nutrient dynamics in perched dune lakes, with particular emphasis on the effects of water level fl uctuations and grazing organisms. We then superimpose visitor activities and climate change and increased climatic variability on model functions, and suggest how they are likely to intensify interactions between nutrient processes and fluctuating hydrology. We predict that visitor-mediated nutrient inputs will stimulate algal growth, but that the consequences of this increase in algal biomass, especially for consumer organisms (but also for visitors themselves), will differ between wet (high water level) and dry (low water level) periods. Understanding the dynamic nature of algal production in perched dune lake ecosystems in the context of an increasingly variable climate, is essential to inform how these systems should be managed, particularly for the highly visited systems that inevitably experience the additional stress of nutrient inputs from visitors. Maintaining the natural oligotrophic status of perched dune lakes is an important management principle.
Proceedings of the Royal Society of Queensland
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Environmental Science and Management not elsewhere classified