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Penguins have been recently identified as useful bioindicators of mercury (Hg) transfer to food webs in the Southern Ocean over different spatial and temporal scales. Here, feather Hg concentrations were measured in adults and chicks of all the seven penguin species breeding in the southern Indian Ocean, over a large latitudinal gradient spanning Antarctic, subantarctic and subtropical sites. Hg was also measured in feathers of museum specimens of penguins collected at the same sites in the 1950s and 1970s. Our aim was to evaluate geographical and historical variations in Hg transfer to penguins, while accounting for feeding habits by using the stable isotope technique (δ 13 C, habitat; δ 15 N, diet/trophic level). Adult feather Hg concentrations in contemporary individuals ranged from 0.7 ± 0.2 to 5.9 ± 1.9 μg g −1 dw in Adélie and gentoo penguins, respectively. Inter-specific differences in Hg accumulation were strong among both adults and chicks, and mainly linked to feeding habits. Overall, penguin species that feed in Antarctic waters had lower feather Hg concentrations than those that feed in subantarctic and subtropical waters, irrespective of age class and dietary group, suggesting different Hg incorporation into food webs depending on the water mass. While accounting for feeding habits, we detected different temporal variations in feather Hg concentrations depending on species. Notably, the subantarctic gentoo and macaroni penguins had higher Hg burdens in the contemporary rather than in the historical sample, despite similar or lower trophic levels, respectively. Whereas increases in Hg deposition have been recently documented in the Southern Hemisphere, future monitoring is highly needed to confirm or not this temporal trend in penguins, especially in the context of actual changing Hg emission patterns and global warming. [ABSTRACT FROM AUTHOR]

The article discusses research on the utilization of stable isotopes of body feathers to investigate seasonal isotopic niche changes of four southern procellariiformes and the level to which individuals are specialised relative to their population within each season. It states that niche variation has important implications for ecological interactions and conservation biology. It stresses that the study highlights the utility of feather isotopic signature of albatrosses for determining trophic niche width (TNW) and points out the necessity to develop such new approaches to better depict niche variations at both population and individual levels.

The article presents the study conducted regarding the use of nitrogen and carbon isotope values of individual amino acids (AA) in determining the foraging ecology of the four penguin species in Southern Ocean. The study aims to identify these values of individual amino acids which isolated from the penguins' chick blood foraging in various oceanic regions. It shows that the carbon isotope values of all AAs have declined with latitude while the difference in the nitrogen isotope values of the penguins is due to the difference of their trophic levels and foraging locations. The result shows that the isotopes reflect the relative trophic level of the species.