Taxa-based indices of biotic integrity (IBIs) are commonly used to evaluate ecological well-being of freshwater systems including streams, rivers, and wetlands. The occurrence and prevalence of taxa and functional groups are correlated in multivariate space to disturbance gradients where ultimately the relative abundance of sensitive to tolerant taxa provide an indication of ecosystem integrity or impairment. Because IBIs are taxa-based they are inherently sensitive to regional differences in biodiversity, therefore IBIs need to be constructed regionally and for specific habitat types (e.g. streams vs wetlands). Community body size distributions, on the other hand, are ataxic and as such more universal (i.e. all communities have body sizes). Community body size distributions represent an emergent property of aquatic communities and have been used to infer food web function. It is hypothesized that ataxic community body size distributions can provide insightful metrics of ecosystem integrity complementary to traditional taxa-based metrics. Community size spectra (CSS) is a theoretical approach for examining patterns in community (or assemblage) – wide body size distribution. CSS quantifies the relative abundance of individuals, regardless of taxonomic identity, across a range of body sizes. There is a near universal decline in abundance with increasing body size in aquatic systems directly related to size-related metabolism and gape-limited foraging. The rate of decrease, often referred to as the CSS slope, represents food web efficiency or degree of biomass/energy in the smaller size classes (lower trophic positions) passed to successively larger (often higher trophic position) organisms. The CSS slope responds in a predictable fashion to internal food web changes in species relative abundance as well as external watershed and habitat characteristics. In general, however, the CSS is broadly stable around a long-term mean and deviations from that mean (outside typical temporal variability) are indicative of ecosystem change. In this presentation I will share a series of published and unpublished case studies to demonstrate the responsiveness of CSS and make a case for the use of ataxic community body size distributions as complementary measures ecosystem integrity.