Age, diet, and season do not affect longevity-related differences in peroxidation index between Spisula solidissima and Arctica islandica.

The susceptibility of membrane lipids to peroxidation (peroxidation index [PI]) increases with the double bond content of fatty acids and is inversely correlated to longevity in mammals, birds, and bivalve molluscs. In molluscs, membrane polyunsaturated fatty acids content can be affected by temperature, nutrition, and the individual's age. In this study, we evaluated how these three parameters may alter correlations between PI and longevity. We determined the fatty acid and dimethyl acetal compositions of phospholipids from gill mitochondrial and nonmitochondrial preparations from the short-lived Spisula solidissima (maximum longevity = 37 years) and the long-lived Arctica islandica (maximum longevity = 507 years) exposed to diet abundance and temperature (season) treatments. We also evaluated the effect of individual age on PI in S. solidissima (from 6 to 23 years). The temperature increase from winter to summer (2 to 12°C) coincided with decreases in values of PI, proportions of eicosapentaenoic acid, and dimethyl acetals. Higher microalgae supplementation increased polyunsaturated fatty acids and PI and decreased dimethyl acetals; age did not affect the PI in S. solidissima. Our finding that the PI of A. islandica remained significantly lower than that of S. solidissima in corresponding fractions throughout treatments suggests that longevity-related differences in PI are resilient to environmental conditions.