Filters: Tags: longitudinal gradients (X)1 result (32ms)
Spatial Variation in Î´15N and Î´13C Isotopes in the San Juan River, New Mexico and Utah: Implications for the Conservation of Native Fishes
Spatial patterns of resource use by small-bodied fishes in the San Juan River were examined using stable isotopes. Using Î´15N of fishes as an index of trophic position, our data suggest both native and non-native fishes primarily consumed macro-invertebrates. The Î´13C of these fishes further suggested a detritus-based food web, from which most species fed on chironomids in low-velocity habitats. A two-way ANOVA revealed a significant interaction between trophic level of fish species and longitudinal position in the river. This interaction was primarily attributed to a decline in trophic level of non-native red shiner Cyprinella lutrensis, relative to other species, in upstream reaches of the river. In addition,...