Preservation effects on stable isotope analysis of fish muscle

We evaluated the effect of salt and formalin-ethanol sample preservation on carbon and nitrogen isotopic signatures of fish muscle tissue. We found statistically significant effects of the tissue preservation technique on both delta(13)C and delta(15)N; however, the magnitude of change was small and directionally uniform. Isotopic shifts were similar to those observed in previous studies in which formalin was used to preserve samples of quail blood and muscle and sheep blood. Because salt preservation caused minimal isotopic shifts (+0.13parts per thousand delta(13)C, +0.72parts per thousand delta(15)N), we propose salt as an easy, inexpensive preservation technique for biological samples collected in remote field settings. Specimens preserved with formalin and ethanol were minimally affected by preservation (-1.12parts per thousand delta(13)C, +0.62parts per thousand delta(15)N) and therefore may be suitable for ecological applications of stable isotope analysis when carbon and nitrogen sources are differentiated by more than 2parts per thousand. Further research is required to evaluate potential long-term storage effects of formalin fixation and alcohol preservation on isotopic signatures of fish tissues.