Publication Abstract

Tissue and fixative dependent shifts of d13C and d15N in preserved ecological material

C. Sweeting, N. Polunin and S. Jennings

Carbon and nitrogen stable isotope analyses are routinely used to investigate aquatic food webs, and have potential application in retrospective investigations using archived materials. However such analyses assume that storage does not alter isotopic signatures of materials preserved, or that changes in isotopic composition during storage are predictable. Here we examine preservation shifts on cod (Gadus morhua) muscle, roe and liver tissue over 21 months following preservation in 80% ethanol, 4% formaldehyde and by freezing. Preservation shifts were not consistent among tissues. High protein tissues exhibited greater δ¹⁵N shifts than low protein tissues in 4% formaldehyde, while greater δ¹³C shifts occurred in relatively higher fat tissues when preserved in alcohol. Freezing did not change isotopic signatures. Responses of δ¹⁵N and δ¹³C are explained by differences in the preservative's isotopic signature and reaction properties and biochemical composition of the tissues preserved. The results clarify some of the processes that lead to isotopic change during preservation.

Reference:

C. Sweeting, N. Polunin and S. Jennings (2004) Tissue and fixative dependent shifts of d13C and d15N in preserved ecological material. Rapid Communications in Mass Spectrometry, 18: 2587-2592