Marine management has the central aim of protecting the health of the system, whether that health relates to natural functioning or the wellbeing of Man. Therefore it is helpful to think of health as defined under FOUR categories: medical, biological, societal and economic, each of which requires protecting. If our main aim in marine management is to protect health then, as far as the biology is concerned, we can consider health at each of SIX different levels of biological organisation and judge changes in these against uncertainty and variability in the system (McLusky

and Elliott, 2004 and Borja et al., 2010a): • Health of the cell – as functioning, at a molecular/biochemical level, maintenance of cellular selleckchem processes; as structure as the integrity of the organelles. In essence,

the detection of change in health and consequent aim by management is to ensure those levels are fit-for-survival. We take the precautionary approach which assumes that stress will be transferred through the natural system but in reality the system can absorb stress, termed environmental homeostasis ( Elliott and selleck Quintino, 2007). As we go through each of these SIX levels, the complexity increases, it is more difficult to detect a response, a greater level of stress is needed to create a response and the response times increase. We assume, through the precautionary principle, that the effects Lck at one biological level, e.g. cell, will be transmitted to another, e.g. population if the stress is not removed although systems have an inherent ability to reduce or remove the effects of stress (individual or environmental homeostasis) ( Elliott and Quintino, 2007). We can then adopt the language of health for wider environmental change and the means of addressing problems: hence we can regard adverse change as SEVEN symptoms of marine ecosystem pathology for wider use and identify a few indicators of change for a wide and general application across human-derived problems (Box 3). It is interesting that the determination of unhealthy ecosystems

is analogous with medicine which uses diagnosis, prognosis, treatment and prevention which can be directly translated to environmental systems in which we carry out FIVE stages: of assessment, prediction, remediation/creation/restoration, recovery and prevention. We manage in order to deliver a healthy system which we can define as a system fit-for-purpose – i.e. the big idea fulfilling ecology and social-economy. Taking ideas from the human, medical system, we can show the similarities in approach whereby we make a diagnosis of change or a prognosis of future change – if the system becomes or is likely to become degraded then we bring in treatment or prevention of change, we may even have to restore the system to health by various measures ( Elliott et al., 2007 and Borja et al.