Oil pollution increases plasma antioxidants but reduces coloration in a seabird

Abstract

It has been suggested that condition-dependent signals may be a useful measure of environmental quality. In this study, we tested the hypothesis that oil pollution enhances oxidative stress and impairs expression of a carotenoid-based signal in a wild population of the yellow-legged gull (Larus michahellis). During the courtship period, a group of gulls were fed a supplementary diet containing heavy fuel oil from the Prestige oil spill and were compared with control gulls fed a similar supplementary diet without fuel oil. Blood levels of polycyclic aromatic hydrocarbons, the most toxic components of crude oils, were higher (30%) in the Prestige oil-fed gulls than in the control gulls. Plasma concentrations of vitamin E and carotenoids were also significantly higher in the Prestige oil-fed gulls (31 and 27%, respectively). Although, the plasma levels of lipid peroxidation markers were higher (13%) in gulls fed with Prestige oil than in the control gulls, these differences were not significant, possibly because of the small number of gulls analyzed. The red bill spot was significantly smaller (16%) in the oil-fed gulls than in the control individuals. This study provides the first experimental evidence that a carotenoid-based signal in a free-living seabird is affected by exposure to oil pollution and is hence indicative of environmental quality. Since the yellow-legged gull belongs to a complex of species widely distributed throughout the northern hemisphere, the method described may constitute a useful tool for evaluating sub-lethal effects of oil spills in seabirds.

Integument colouration in relation to persistent organic pollutants and body condition in arctic breeding black-legged kittiwakes (Rissa tridactyla)

“…Thereby, our study provides evidences that POPs contamination can affect integument carotenoidbased colouration. This is consistent with previous work since Pérez et al (2010a) showed that organic compounds negatively influence the red bill spot size of adults yellow-legged gulls (Larus michahellis) during the courtship period. Moreover, Bortolotti et al (2003) found that colouration of ceres and lores were disrupted by an enriched-PCB diet in captive American kestrels: exposed males were duller than controls, and juveniles of both sexes were brighter in winter.…”

“…Under this scenario, female kittiwakes with the highest POP levels could allocate preferentially their carotenoids towards protective physiological functions (immunity, antioxidant capacity) whereas female kittiwakes with the lowest POP levels could allocate preferentially the available carotenoids towards sexual signaling. These results are thus consistent with the existence of a trade-off between allocations of carotenoids to sexual ornaments signaling versus physiological functions for detoxification processes (Pérez et al, 2010a). However, we did not perform any physiological analysis in our study and, thus, the existence of this trade-off could only be confirmed by coupling integument and plasma carotenoid measurements and POP levels in future studies.…”

“…the most colourful kittiwakes are those with the best immunological status. This implies that healthy individuals should require fewer carotenoids for immune defenses and could therefore allocate more carotenoids to enhance colouration (Pérez et al, 2010a;Pérez-Rodríguez and Viñuela, 2008). However, this hypothesis could only be confirmed by measuring carotenoids in integuments and plasma coupled to the measure of immunological parameters.…”

“…They also maintain the structural integrity of immune cells by removing free radical molecules that are produced through normal cellular activity, but also through environmental stressors (Chew, 1996). Consequently, carotenoids promote survival (immunity, antioxidant capacity) suggesting that a tradeoff may exist between allocations of carotenoids to sexual ornaments signaling versus physiological functions for self-maintenance (Eraud et al, 2007;Pérez et al, 2010a;Von Schantz et al, 1999). It is widely assumed that condition-dependence is a common feature of sexual displays (Kristiansen et al, 2006;Martinez-Padilla et al, 2007;Mougeot et al, 2006Mougeot et al, , 2007Pérez-Rodríguez and Viñuela, 2008;Velando et al, 2006).…”

“…In addition to this effect of body condition on carotenoid-based colouration, a few studies have suggested that environmental pollution could also affect, and more precisely disrupt, the expression of avian colouration (Eeva et al, 1998;Pérez et al, 2010a). For example, persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs) and pesticides appear to reduce the expression of carotenoid-based colouration.…”