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Brasso R.L.,University of North Carolina at Greensboro | Chiaradia A.,Phillip Island Nature Park | Polito M.J.,Louisiana State University | Raya Rey A.,CONICET | Emslie S.D.,University of North Carolina at Wilmington
Marine Pollution Bulletin | Year: 2015

The wide geographic distribution of penguins (Order Sphenisciformes) throughout the Southern Hemisphere provided a unique opportunity to use a single taxonomic group as biomonitors of mercury among geographically distinct marine ecosystems. Mercury concentrations were compared among ten species of penguins representing 26 geographically distinct breeding populations. Mercury concentrations were relatively low (≤2.00. ppm) in feathers from 18/26 populations considered. Population-level differences in trophic level explained variation in mercury concentrations among Little, King, and Gentoo penguin populations. However, Southern Rockhopper and Magellanic penguins breeding on Staten Island, Tierra del Fuego, had the highest mercury concentrations relative to their conspecifics despite foraging at a lower trophic level. The concurrent use of stable isotope and mercury data allowed us to document penguin populations at the greatest risk of exposure to harmful concentrations of mercury as a result of foraging at a high trophic level or in geographic 'hot spots' of mercury availability. © 2015 Elsevier Ltd.

Chiaradia A.,Phillip Island Nature Park | Forero M.G.,CSIC - Donana Biological Station | Hobson K.A.,Environment Canada | Cullen J.M.,Monash University
ICES Journal of Marine Science | Year: 2010

After the disappearance of primary prey, seabirds exhibit gradually decreased breeding performance, and eventually the population size drops. Results are presented of an investigation into the diet of little penguins (Eudyptula minor) at Phillip Island, Australia, during a period when their key prey, pilchard (Sardinops sagax), declined dramatically. Data from stomach flushing (1982-2006) were used, supported by stable isotope (δ 15N, δ13C) analyses of blood samples (2003, 2004, and 2006). The effect of the pilchard mortality on penguin diet was immediate, the birds shifting to a diet almost devoid of pilchard, and this was followed by 2 years of low breeding success, with considerably fewer penguins coming ashore. During periods when pilchard was not part of the diet, penguins consumed prey of a higher trophic level, e.g. higher values of δ15N. Variability in penguin blood δ15N coincided with years of low prey diversity. The disappearance of pilchard resulted in a decrease in prey diversity and led penguins to "fish up" the foodweb, possibly because of the simplified trophic structure. After 1998, however, breeding success re-attained average levels and the numbers of penguins coming ashore increased, probably because of increased abundance of prey other than pilchard after a 3-year period of food scarcity. Although little penguins apparently compensated over time, a less-flexible diet could make them ultimately vulnerable to further changes in their foodweb. © 2010 International Council for the Exploration of the Sea.

Brasso R.L.,University of North Carolina at Wilmington | Drummond B.E.,University of North Carolina at Wilmington | Borrett S.R.,University of North Carolina at Wilmington | Chiaradia A.,Phillip Island Nature Park | And 2 more authors.
Environmental Toxicology and Chemistry | Year: 2013

The authors hypothesized that the catastrophic annual molt of penguins (Sphenisciformes) would lead to reduced intraindividual variation of mercury concentrations in body feathers. While mean mercury concentrations varied significantly among 8 penguin species, intraindividual variability did not differ among species and was 3 times lower than values observed in other seabirds. The findings of the present study suggest that a single body feather collected at random per individual can be adequate to estimate mercury exposure at the population level in penguins. © 2013 SETAC.

Zimmer I.,University of Strasbourg | Zimmer I.,French National Center for Scientific Research | Ropert-Coudert Y.,University of Strasbourg | Ropert-Coudert Y.,French National Center for Scientific Research | And 6 more authors.
Marine Biology | Year: 2011

A complex interaction of biotic and abiotic factors influences animal foraging activity. It is often difficult to understand which factors may affect animals' foraging and how it is affected. For instance, whereas the effect of sexual dimorphism on foraging activity has been reported in several species, little is known of the complex interactions between variables acting at a finer scale, e.g. the variability of body mass within a sex. Evaluating the importance of these finer scale factors is also essential to the understanding of foraging behaviour. We propose here a simple approach by applying principal component analysis (PCA) in a novel way to examine relationships between biotic and abiotic factors affecting foraging behaviour of top predators. We studied female little penguins (Eudyptula minor) of known age, carrying miniature accelerometers during the guard stage of breeding. Surprisingly, the body mass of the females did not influence any of the foraging parameters, but females foraging later in the breeding season dived shallower and more often, showing a strong correlation with laying date. Similarly, the diving effort of females was greater with increasing chick age within the same breeding stage. These results indicate that for female little penguin, the relationship between changes in prey availability and hunting effort can change at a fine scale, within a breeding stage. Therefore, any analysis of little penguin foraging behaviour during breeding should consider the timing in relation to the breeding season. We encourage researchers to develop the use of this PCA approach as it could help clarify the complexity of the underlying mechanisms determining foraging activity and we propose that it should be used as a first step of foraging behaviour analysis, before examining a particular relationship. © 2010 Springer-Verlag.

Ritchie W.J.,La Trobe University | Green J.A.,La Trobe University | Green J.A.,University of Liverpool | Dann P.,Phillip Island Nature Park | And 3 more authors.
Emu | Year: 2010

Abdominally implanted data-loggers have been used to study the behaviour and physiology of birds, with no detectable negative effects. This technique has great potential for smaller and streamlined species, since these animals tend to be more prone to the negative effects that may be associated with externally attached devices. We conducted the first assessment of the impacts of abdominally implanted heart-rate data-loggers on a smaller species, the Little Penguin (Eudyptula minor), which weighs ∼1.1kg. The number and duration of trips to sea were recorded in male penguins implanted with a device (n≤10) and compared with a control group not implanted with a device (n≤10). Trips were recorded for the entire duration of the Penguins' winter non-breeding period, which for this species is the time of year when their energy budgets are most delicately balanced. The heart-rate data-loggers appeared to have no effect on percentage of time spent at sea, and the number and duration of overnight trips of 25 days or 626 days. Implanted Penguins undertook fewer trips of 1-day duration but the duration of these trips of 1 day was not affected. Individual Penguins showed highly variable foraging behaviour and the difference in the number of trips of 1 day may be attributed to individual specialisation in foraging behaviour. © 2010 Royal Australasian Ornithologists Union.

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