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Data from 35 published studies were collated to examine patterns in the trophic enrichment of ¹³C of consumers. Because both delta ¹³C and delta ¹⁴N vary systematically across ecosystems, it was necessary to standardize for such differences before combining data from numerous sources. Relationships of these measures of ecosystem-standardized delta ¹³C to ecosystem-standardized trophic position ( DELTA delta ¹⁵N) for freshwater, estuarine, coastal, and open-ocean and for all aquatic ecosystems yielded regression equations of low predictive capability (average of 20% explained variance in delta ¹³C). However, differences were observed in the slopes between delta ¹³C and standardized trophic position when data were examined study-specifically: the average trophic fractionation of ¹³C was found to increase from + 0.2omicron for freshwater to + 0.5omicron for estuarine to + 0.8omicron for …