Use of isotopic analysis of vertebrae in reconstructing ontogenetic feeding ecology in white sharks

摘要

We conducted stable C-13 and N-15 analysis on white shark vertebrae and demonstrated that incremental analysis of isotopes along the radius of a vertebral centrum produces a chronological record of dietary information, allowing for reconstruction of an individual's trophic history. Isotopic data showed significant enrichments ill N-15 with increasing sampling distance from the centrum center, indicating a correlation between body size and trophic level. Additionally, isotopic values verified two distinct ontogenctic trophic shifts in the white shark: one following parturition, marking a dietary switch from yolk to fish; and one at a total length of > 341 cm, representing a known diet shift from fish to marine mammals. Retrospective trophic-level reconstruction using vertebral tissue will have broad applications in future studies on the ecology of threatened, endangered, or extinct species to determine life-long feeding patterns, which would be impossible through other methods.