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Marine predators may undergo remarkable dietary changes through time as a result of both anthropogenic and natural changes in the environment, but this variability is often difficult to tackle and seldom incorporated into ecosystem models. This paper uses the stable isotope ratios of carbon and nitrogen in skeletal material of South American sea lions from Brazilian scientific collections to investigate whether these animals modified their diet from 1986 to 2009, as reported for other marine predators in the region. Stable isotope ratios indicated that demersal potential prey were always enriched in [sup.13]C as compared with pelagic prey. Accordingly, the absence of any statistically significant correlation between stranding year and the δ[sup.13]C values of adult males indicated no major increase in the consumption of pelagic prey from 1986 to 2009. Likewise, the results of the mixing model SIAR revealed a mixed diet including pelagic and demersal prey, with a central role for demersal fishes throughout the whole period. Furthermore, SIAR suggested no major changes in the proportion of pelagic and demersal prey in the diet of adult male South American sea lions during the past three decades. Demersal fishes were also relevant prey for juvenile South American sea lions during the whole period, but they always consumed a larger proportion of pelagic prey than the adults did. These results suggest no major changes in the diet of male South American sea lions during the past three decades in southern Brazil, contrary to what has been reported for other to predators in the regions and for the species in northern Patagonia., Introduction Human activities have impacted most of the marine ecosystems around the world (Halpern 2008), and only retrospective studies can give us a full account of the magnitude of the [...]

In diving seabirds, sexual dimorphism in size often results in sex-related differences of foraging patterns. Previous research on Magellanic penguins, conducted during the breeding season, failed to reveal consistent differences between the sexes on foraging behavior, despite sexual dimorphism. In this paper, we tested the hypothesis that male and female Magellanic penguins differ in diet and foraging patterns during the non-breeding period when the constraints imposed by chick rearing activities vanish. We used stable isotope ratios of carbon and nitrogen in feather and bone to characterize the diet and foraging patterns of male and female penguins in the South Atlantic at the beginning of the 2009-2010 and 2010-2011 post-breeding seasons (feathers) and over several consecutive breeding and migratory seasons (bone). The mean [δ.sup.13]C and [δ.sup.15]N values of feathers showed no differences between the sexes in any of the three regions considered or in the diet composition between the sexes from identical breeding regions; however, Bayesian ellipses showed a higher isotopic niche width in males at the beginning of the post-breeding season. Stable isotope ratios in bone revealed the enrichment of males with [δ.sup.13]C compared with females across the three regions considered. Furthermore, the Bayesian ellipses were larger for males and encompassed those of females in two of the three regions analyzed. These results suggest a differential use of winter resources between the sexes, with males typically showing a larger diversity of foraging/migratory strategies. The results also show that dietary differences between male and female Magellanic penguins may occur once the constraints imposed by chick rearing activities cease at the beginning of the post-breeding season., Introduction Body size is important to explain between-species differences in diving performance (Schreer and Kovacs 1997; Watanuki and Burger 1999) and within-species differences, in which individuals differ significantly in body [...]

This paper is a contribution to a better understanding of tsunamigenic potential from large submarine earthquakes. Here, we analyse the tsunamigenic potential of large earthquakes occurred worldwide with magnitudes around Mw 7.0 and greater, during a period of 1 year, from June 2013 to June 2014. The analysis involves earthquake model evaluation, tsunami numerical modelling, and sensors' records analysis in order to confirm the generation or not of a tsunami following the occurrence of an earthquake. We also investigate and discuss the sensitivity of tsunami generation to the earthquake parameters recognized to control the tsunami occurrence, including the earthquake magnitude, focal mechanism and fault rupture depth. A total of 23 events, with magnitudes ranging from Mw 6.7 to Mw 8.1 and hypocenter depths varying from 10 up to 585 km, have been analyzed in this study. Among them, 52% are thrust faults, 35% are strike-slip faults, and 13% are normal faults. Most analyzed events have been occurred in the Pacific Ocean. This study shows that about 39% of the analyzed earthquakes caused tsunamis that were recorded by different sensors with wave amplitudes varying from few centimetres to about 2 m. Some of them caused inundations of low-lying coastal areas and significant damages in harbours. On the other hand, tsunami numerical modeling shows that some of the events, considered as non-tsunamigenic, might trigger small tsunamis that were not recorded due to the absence of sensors in the near-field areas. We also find that the tsunami generation is mainly dependent of the earthquake focal mechanism and other parameters such as the earthquake hypocenter depth and the magnitude. The results of this study can help on the compilation of tsunami catalogs. [ABSTRACT FROM AUTHOR]

Among Anoplura, the family Echinophthiriidae includes species that infest pinnipeds and otters. Previous evidence obtained from pinnipeds infested by echinophthiriids, specifically from seals, indicates that flippers are the preferred infestation sites, while lice from fur seals select areas in the pelage. We studied habitat selection of Antarctophthirus microchir on South American sea lion pups (Otaria flavescens Shaw, 1800) from Patagonia, Argentina, during the austral summer of 2009. We found a clear pattern of habitat selection: eggs are laid on the dorsal surface; nymphs 1 hatch there and then migrate to the belly, where they develop into adults and copulate; and then ovigerous females return to the dorsal surface. On the one hand, nymphs 1 are characterised by their low locomotory ability; therefore, the fact that they migrate as soon as they hatch suggests a clear pressure leading to microhabitat restriction. On the other hand, the described pattern of microhabitat selection seems to respond to the physiological requirements of each stage, which vary according to the physiological process considered, e.g. oviposition, morphogenesis, hatching and development. Accordingly, it appears that A. microchir would prefer the host's ventral area for development and copulation and the dorsal area for oviposition. However, the causes of this pattern are not clear, and many factors could be involved. Considering that sea lion pups periodically soak at high tides, and that prolonged immersion and very high humidity are known to be lethal for lice eggs, selecting the dorsal area would be advantageous for oviposition because it dries much faster. Furthermore, because humidity should be retained for longer periods on the ventral surface of the pup, wetter conditions on the sea lion would prevent desiccation of the nymphs in the very arid environment where O. flavescens breeds.