Dietary histories of herbivorous loricariid catfishes: Evidence from δ13C values of otoliths

Abstract

The ecology of many Neotropical fishes is difficult or often impossible to study during rainy seasons. Thus, ecological studies of tropical fishes are usually performed on fish captured only during dry seasons. Because otoliths preserve a record of life history, this study evaluated the utility of otolith stable isotope values for the investigation of trophic ecology of Neotropical fishes (specifically herbivorous loricariid catfish) throughout their lives. Because plant dietary materials have δ13C values that are determined by their photosynthetic pathways, metabolism and environmental conditions, different plants may impart different isotope values on fish otoliths that reflect consumption of these plants. The δ 13C(otolith) values of xylophagous Panaque nigrolineatus captured in the field were significantly lower than those of algivorous Hypostomus regani from a nearby region. A laboratory experiment wherein Hypostomus sp. had δ13C(otolith) values that reflected the δ13C values of their plant diet and additional evidence indicate that δ13C(otolith) values in loricariid catfish otoliths can record dietary history. © 2006 Springer Science+Business Media B.V.