An indicator is the measured feature in the ecosystem (e.g. particulate nitrogen); an indicator category is generated by combining one or more related indicators (e.g. the category ‘nutrients’ is made up of particulate nitrogen and particulate phosphorus); an index is generated by combining related categories (e.g. the index ‘water quality’ is made up of nutrients, water clarity, chlorophyll-a and pesticides); the overall score is generated by one or more index (e.g. water quality, coral, seagrass and fish indices can make up an inshore marine zone score).
Indicators, categories and indices are displayed in a ‘coaster’ to demonstrate which indicators are aggregated to produce category and index scores.