摘要：We investigated the ability of otolith stable nitrogen isotope ratio (δ 15 N) to discriminate among fishes from southern Illinois streams that differed in proportions of watershed agricultural land. Otolith δ 15 N was nearly as effective as muscle δ 15 N in identifying fishes from individual sites with different percentages of agricultural land cover; both had accuracies of >75%. However, because of the relatively low N content of otoliths, substantial amounts (~8 mg) of otolith material are required for δ 15 N analysis compared to fish muscle tissue (~0.3 mg), which precludes the use of otolith δ 15 N as an indicator of dietary and environmental history for small fishes.
