2010 Volume 5 Issue 2 Pages 79-82
Stable isotope analyses are often used for the estimation of food web structures based on empirical fractionation (i.e., enrichment of carbon isotope signatures at 0–1‰ with one trophic level, and that of nitrogen at 3–4‰). We examined the effect of 80% ethanol fixation on both carbon and nitrogen stable isotope signatures of six species of macrobenthos samples. The effect of fixation was inconsistent (i.e. both enrichment and depletion occurred). The shift of nitrogen isotope signatures due to fixation ranged from −0.3 to +0.8‰, and the carbon signatures of fixed samples showed enrichment by −0.3 to +1.3‰ depending on the species. These changes would clearly affect estimation of trophic levels and energy flow in food webs. Ethanol fixation may not be a smart choice because of the inconsistency of the effect on isotope signatures. However, if the effect was corrected for each species, ethanol-fixed samples can be practically useful for food web analyses using stable isotopes.
