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The giant Antarctic Octopus Megaleledone setebos is the largest Southern Ocean octopod whose ecology is poorly known. Here, we study ontogenetic shifts of habitat and trophic ecology of M. setebos throughout its life cycle by stable isotopic analysis of [delta].sup.13C and [delta].sup.15N on its beaks collected from the diet of Antarctic toothfish in Amundsen and Ross Seas (Antarctica). Values of [delta].sup.13C (from - 24.3 to - 19.4â°) differed between beaks of individuals from different capture locations, thus reflecting the ability of M. setebos living in different habitats. Despite sequential sampling along beaks showed a small (< 2.3â°), but significant variation in lower beak's [delta].sup.13C values, a relation with [delta].sup.15N values suggests that such differences are related to changes in the diet with M. setebos inhabiting the same area its entire life. Values of [delta].sup.15N differed between beaks of individuals from different capture locations, suggesting that different habitats of M. setebos are associated with different diets. Serial sampling along the beaks (from + 4.2 to + 10.7â°) suggests an ontogenetic change of, at least, one trophic level from juvenile to adult. We also report a capture of two large intact specimens from Dumont D'Urville Sea (Antarctica): a male with 1150 mm of total length and 18,300 g of mass and a female with 1030 mm of total length and 10,061 g of mass. The beaks of these both specimens, confirmed to be of M. setebos through genetic analysis, were also used to confirm the identification of M. setebos collected from Antarctic toothfish stomachs., Author(s): José P. Queirós [sup.1], Mark Fenwick [sup.2], Darren W. Stevens [sup.2], Yves Cherel [sup.3], Jaime A. Ramos [sup.1], José C. Xavier [sup.1] [sup.4] Author Affiliations: (1) grid.8051.c, 0000 0000 [...]

Feeding habits of the four most abundant deep-sea demersal trawl-caught macrourids on Chatham Rise, New Zealand, were examined from stomach contents. Two species were predominantly benthic foragers: Coelorinchus bollonsi on infaunal and epifaunal polychaetes, and C. aspercephalus on epifaunal crustaceans; and two species were predominantly mesopelagic foragers; C. oliverianus on calanoid copepods, and Lepidorhynchus denticulatus on mesopelagic crustaceans. The most important predictors of diet variability were identified using distance-based linear models and included areal predictors in all four species, fish size in C. aspercephalus, C. bollonsi and L. denticulatus, and sample year in C. bollonsi. Cluster analyses showed that the diets of C. aspercephalus and C. bollonsi were most distinct. There was a greater interspecific similarity in diet in the spatial and fish size subgroups of C. oliverianus and L. denticulatus, than at the species level. Failing to account for areal, temporal, and ontogenetic variability in diets may bias evaluations of resource competition., Author(s): Darren W. Stevens [sup.1] , Matthew R. Dunn [sup.1] Author Affiliations: (1) grid.419676.b, 0000000092525808, National Institute of Water and Atmospheric Research Ltd, , 301 Evans Bay Parade, Greta Point, [...]