Figure 1.
δ15N values in four trophic groupings of litter-based invertebrates collected above and below waterfall barriers to salmon migration on the Clatse and Neekas Rivers, British Columbia. Invertebrates are ranked (left to right) based on increasing consumption of animal protein (see methods). t-test results: ** denotes p < 0.01; *** denotes p < 0.001.