I want to analyse the diets of infaunal invertebrates from a deep-sea methane hydrates site. The organisms had been preserved in 10 % formalin and then transferred to 70 % ethanol for about 4 years now. I know this preservation method affects the carbon stable isotopic signature and, depending on the organisms, the nitrogen stable isotopic signature too. But I'm having some trouble finding information on the literature about the effects of preservation on sulfur stable isotopes.
Thanks!
Hello Neus Campanyà-Llovet,
Effect of long-term storage following preservation with formalin has been found to bring about no detrimental effects on the stable sulfur isotopes of museum preserved piscifauna. The following link supports the claim ; however in cases of infaunal invertebrates the effect might be different due to greater penetration and conformational changes in various moieties.
Nonetheless, it is a very interesting and seldom focused area of study and I sincerely wish you success in your research.
Regards,
Dr. Abhishek Mukherjee
Hi Neus,
Some studies (see Edward 2002) on 34S have shown that fixation with formalin has some effects but they are manageable, but one needs to be careful from acidifying the sample, since acidification does have a measurable effect on 34S values. Please have a look at the attached papers. The reference sections of those papers will give you lead to other information. Hope this helps.
Tomas
Hi Neus,
I would say it highly depends on which invertebrates you plan to analyze... Both from the literature and my own experience, I'd say such effects can be taxon-specific.
Effects on d13C are strong and clear, effects on d15N and d34S tend to be less frequent. Also, in some cases formalin-induced isotopic deviation tends to be stable in time, so if you have some relevant samples, you could try to calculate some kind of correction factor.
Hope this helps
Loïc
