Ecological integrity of aquatic systems

Focusing on the ecological integrity of large river systems has suggested the rethinking of the entire issue from a landscape perspective. Ecological integrity is impossible without biological integrity. However, it appears improbable that highly localized measures of biological integrity can be used for effective, scientifically justifiable extrapolations to landscape- or system-level ecological integrity. It may be more reasonable to make measurements at the level of organization of interest, i.e. larger spatial and temporal scales. In addition, human society and natural systems have been coevolving since the agricultural revolution and, arguably, well before then. Two types of coevolution between human society and natural systems appear possible: (1) an 'arms-race' in which human society ignores changes in natural systems-essential ecosystem services are lost, resulting in unpleasant consequences for society; or (2) mutualism in which environmental literacy and a feeling of responsibility for natural systems motivate rapid societal response to ecosystem changes and the preservation of ecological integrity. The simplest measures of ecological integrity may be the actions of human society likely to minimize or markedly reduce negative impacts on natural systems. This does not mean substituting such measures for more customary ecological measures, but rather using both types of measurements simultaneously.