Age, oxidative stress exposure and fitness in a long-lived seabird

The need to manage exposure to oxidative stress, which can damage macromolecules, is thought to influence the resolution of life history trade-offs. Oxidative damage is expected to increase with age as a consequence of changes in the optimal investment in defences or repair, and/or because of senescence in antioxidant defence systems, though the pattern might differ between short and long-lived species. However, data on age related changes in damage levels in wild populations are rare. Using cross-sectional and longitudinal data collected over three years, we examine variation in a measure of oxidative damage exposure in known age, wild European Shags (Phalacrocorax aristotelis), a relatively long lived species. The cross-sectional data showed a quadratic relationship between oxidative damage exposure and age: both relatively young and old adults had higher levels than those in middle age. In contrast, a measure of non-enzymatic antioxidant levels did not vary with age. The cross-sectio...