Perceptions of system-identity and regime shift for marine ecosystems

There is growing empirical evidence around the world demonstrating regime shifts of marine ecosystems. But generalizable criteria to detect and define regime shifts are elusive because of: (i) an incomplete scientific understanding of processes underlying regime shifts; (ii) because the baseline state and conditions are ill defined, and; (iii) due to an inherent ambiguity in the concept of system identity. We surveyed marine scientists in Tasmania, Australia, and determined the effect of changing conditions (including type of climate impact, species loss, species composition, spatio-temporal extent, and human intervention) on their perception of marine regime shift. We find, there is an objective difficulty in detecting regime shifts that goes beyond scientific uncertainty and there is disagreement on which configurations of change indeed constitute a regime shift. Furthermore, this difference of opinion was not related to the degree of confidence that scientists indicated when identifying regime shifts. This lack of consensus and seemingly unrelated scientific confidence, may be attributable to value ambiguity around people s attitudes, cognitive biases, and baseline shift. When applying evidenced-based reference points in well-reasoned Ecosystem Based Management, there should be scientific consensus on the manifestation and extent of specific regime shifts, and recognition of value ambiguities influencing scientific perceptions.