Sliding baselines and shuffling species: Implications of climate change for marine conservation

The concept of shifting or sliding baselines refers to the way that significant changes to an ecological system are mistakenly measured against a previous baseline, which may be significantly different from the original state of the system. The concept assumes an 'original state' exists and that a return to that state might be possible, if it could be determined and there was sufficient control of human interference. The concept has been important in both marine conservation planning and fisheries management. However, long periods of exploitation, observed and projected climate change, and the disappearance of some environments, suggest that a return to an original state is unlikely to be achievable in many systems. In addition, protection based on static marine protected areas is unlikely to meet common conservation objectives, as species and habitats are moving and species assemblages shuffling with the changing climate. An alternative to modeling single species distribution changes is to examine change in environmental proxies, such as sea surface temperature (SST). Here, projected changes in SST for the period 2063-2065 from a downscaled ocean model are used to illustrate the similarity to, and movements of, present pelagic environments within conservation planning areas off Eastern Australia. The future environment of small planning areas differs from their present environment and static protected areas might not protect range-changing species. Climate-aware conservation planning should consider the use of mobile protected areas to afford protection to species' changing their distribution, and develop conservation objectives that are not underpinned by a return to historical baselines.