Developing Sub-Indices of Disturbance Variables within each of the four disturbance categories (Land Use/Land Cover, Alteration of River Flows, Sources of Pollution, and Estuary Eutrophication) were combined to create a sub-index of disturbance associated with each category. To calculate the sub-indices, a percent rank was calculated for variable scores in each estuary. Percent rank scores were inverted (i.e. 1-percent rank) where necessary to maintain consistency of interpretation, with low scores representing the highest degree of disturbance. Within each disturbance category, the average of each of the variable percent rank values was calculated. Finally, the percent rank of this average was calculated – this represented the sub-index [...]
