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This Atlas of top predators from the French Southern Territories in the Southern Indian Ocean is asummary of information on the use of the southern Indian Ocean by 22 seabirds and seals species:king penguin, gentoo penguin, Adelie penguin, eastern rockhopper penguin, northern rockhopperpenguin, macaroni penguin, Amsterdam albatross, wandering albatross, black-browed albatross,Indian yellow-nosed albatross, light-mantled albatross, sooty albatross, southern giant petrel,northern giant petrel, southern fulmar, Cape petrel, snow petrel, white-chinned petrel, grey petrel,brown skua, southern elephant seal and Antarctic fur seal.The distribution map of each species was obtained by the use of tracking methods that allowidentifying important areas in the southern Indian Ocean. The determination of zones of high speciesrichness suggests several important areas for top predators. First the breeding colonies andsurrounding zones: Amsterdam and Saint Paul Islands, Marion and Prince Edward islands and the DelCano Rise, Crozet Islands, Kerguelen Plateau and East Antarctica (Adlie Land sector). Second, theupwelling-current zones: Benguela and Agulhas Currents Systems and third several the oceanic zones:the Southwest Indian Ridge (East Bouvetya and the North Subtropical Front), the Mid-Indian Ridge(North of Kerguelen and the Eastern Indian Ocean, the Southeast Indian Ridge (Great Australian Bightand Tasmania, Ob and Lena Banks, and East Antarctica (Prydz Bay - Queen Maud Land sectors, AdlieLand sector).The analysis of distribution indicates that some pelagic species have a much wider foraging rangeoutside the breeding season than during the breeding season (some disperse over very large areas,i.e. wandering albatross). This highlights the urgent need to strengthen collaborations, namelybetween conservation and management organisms such as CCAMLR and the fisheries organisations(RFMOs), to ensure the protection of these species and the conservation of the ecosystem that willalso be beneficial for many other species.In conclusion, although this inventory of areas of key importance is preliminary because of the lackof data on several keystone species such as burrowing petrels which could not be studied in thiswork, the results presented here show an unprecedented improvement in the identification ofpriority areas within the Southern Indian Ocean, which should be the primary targets of site-basedconservation efforts in the near future. The Southern Indian Ocean is not pristine. The most seriousthreats are linked to industrial fishing activities, including fishery discards, bycatch of seabirds andmarine mammals, as well as, in a lesser extent, degradation of marine environments through globaland local pollution. On land, alien introductions and diseases are now the main threats. Despitemuch improvement in the conservation measures taken by several fisheries, especially in thesouthern part of the Indian Ocean, fisheries continue to exert an important negative influence onseveral seabirds, especially on the high seas. However climate change is now increasingly consideredto have a negative impact on seabirds at some Antarctic and sub-Antarctic localities.The long-term monitoring programs on seabirds and seals are funded by the French Polar Institute Paul-Emile Victor (IPEV: programs n 109 ORNITHOECO: Oiseaux et mammifres marins sentinellesdes changements globaux dans locan Austral, resp. H Weimerskirch; and n394 OISEAUXPLONGEURS: Stratgie nergtique des prdateurs marins et variabilit physique et trophique delocan Austral: tude en mer, resp : C-A Bost).The Atlas work was supported by the French Southern Territories (TAAF), the French MarineProtected Areas Agency through the program of bio-regionalisation en vue de ltablissement dunrseau daires marines protges dans locan Austral, les Kerguelen, Crozet, mer Dumont dUrville.; This Atlas of top predators from the French Southern Territories in the Southern Indian Ocean is asummary of information on the use of the southern Indian Ocean by 22 seabirds and seals species:king penguin, gentoo penguin, Adlie penguin, eastern rockhopper penguin, northern rockhopperpenguin, macaroni penguin, Amsterdam albatross, wandering albatross, black-browed albatross,Indian yellow-nosed albatross, light-mantled albatross, sooty albatross, southern giant petrel,northern giant petrel, southern fulmar, Cape petrel, snow petrel, white-chinned petrel, grey petrel,brown skua, southern elephant seal and Antarctic fur seal.The distribution map of each species was obtained by the use of tracking methods that allowidentifying important areas in the southern Indian Ocean. The determination of zones of high speciesrichness suggests several important areas for top predators. First the breeding colonies andsurrounding zones: Amsterdam and Saint Paul Islands, Marion and Prince Edward islands and the DelCano Rise, Crozet Islands, Kerguelen Plateau and East Antarctica (Adlie Land sector). Second, theupwelling-current zones: Benguela and Agulhas Currents Systems and third several the oceanic zones:the Southwest Indian Ridge (East Bouvetya and the North Subtropical Front), the Mid-Indian Ridge(North of Kerguelen and the Eastern Indian Ocean, the Southeast Indian Ridge (Great Australian Bightand Tasmania, Ob and Lena Banks, and East Antarctica (Prydz Bay - Queen Maud Land sectors, AdlieLand sector).The analysis of distribution indicates that some pelagic species have a much wider foraging rangeoutside the breeding season than during the breeding season (some disperse over very large areas,i.e. wandering albatross). This highlights the urgent need to strengthen collaborations, namelybetween conservation and management organisms such as CCAMLR and the fisheries organisations(RFMOs), to ensure the protection of these species and the conservation of the ecosystem that willalso be beneficial for many other species.In conclusion, although this inventory of areas of key importance is preliminary because of the lackof data on several keystone species such as burrowing petrels which could not be studied in thiswork, the results presented here show an unprecedented improvement in the identification ofpriority areas within the Southern Indian Ocean, which should be the primary targets of site-basedconservation efforts in the near future. The Southern Indian Ocean is not pristine. The most seriousthreats are linked to industrial fishing activities, including fishery discards, bycatch of seabirds andmarine mammals, as well as, in a lesser extent, degradation of marine environments through globaland local pollution. On land, alien introductions and diseases are now the main threats. Despitemuch improvement in the conservation measures taken by several fisheries, especially in thesouthern part of the Indian Ocean, fisheries continue to exert an important negative influence onseveral seabirds, especially on the high seas. However climate change is now increasingly consideredto have a negative impact on seabirds at some Antarctic and sub-Antarctic localities.The long-term monitoring programs on seabirds and seals are funded by the French Polar Institute Paul-Emile Victor (IPEV: programs n 109 ORNITHOECO: Oiseaux et mammifres marins sentinellesdes changements globaux dans locan Austral, resp. H Weimerskirch; and n394 OISEAUXPLONGEURS: Stratgie nergtique des prdateurs marins et variabilit physique et trophique delocan Austral: tude en mer, resp : C-A Bost).The Atlas work was supported by the French Southern Territories (TAAF), the French MarineProtected Areas Agency through the program of bio-rgionalisation en vue de ltablissement dunrseau daires marines protges dans locan Austral, les Kerguelen, Crozet, mer Dumont dUrville.

Mesopelagic fish are a key component of the pelagic ecosystem throughout the world’s oceans. Opening and closing nets were used to investigate patterns in the distribution and abundance of mesopelagic fish from the surface to 1000 m on a series of transects across the Scotia Sea from the ice-edge to the Antarctic Polar Front. A total of 141 non-target net hauls were undertaken during three cruises (Nov 2006, Jan 2008 and Mar 2009), with 7852 teleost fish captured, representing 43 species in 17 families. A further 1517 fish were caught in targeted net hauls. The dominant families were the Myctophidae (6961 specimens; 21 species) and Bathylagidae (1467 specimens; 4 species). Few fish were caught in the upper 400 m during daylight, which was attributed to a combination of net avoidance and diurnal vertical migration. Species composition was linked to depth and location and was closely associated with oceanographic features. Diversity was lowest in cold water at the most southerly stations, which were dominated by Electrona antarctica, Gymnoscopelus braueri and Bathylagus antarcticus. Further north, diversity increased with the addition of species such as Krefftichthys anderssoni, Protomyctophum bolini and Electrona carlsbergi. The depth integrated biomass of myctophids was similar across the latitudinal transect and produced an estimate of 4.5 million tonnes in the Scotia Sea. Bathylagids were patchily distributed, but were abundant in the lower mesopelagic zone (>400 m) and are potentially significant zooplankton consumers. Given the biomass of the myctophids and bathylagids coupled with the vertical migrations of many species, these fish are likely to play a significant role in carbon export from the surface waters to the deep ocean.

International audience

Chemical tracers (e. g. stable isotopes or trace metals) are increasingly used to study trophic ecology and feeding habits of marine organisms and various factors can affect their values. The aim of the present study was to provide information on ontogenic effects on stable carbon and nitrogen values (delta C-13 and delta N-15) and on cadmium (Cd) and mercury (Hg) concentrations in 5 cephalopod species from the Bay of Biscay (North-East Atlantic Ocean). To this end, individuals belonging to 3 species showing the widest range of sizes were analysed for muscle delta C-13 and delta N-15 values and muscle Hg, and digestive gland Cd concentrations. Results showed that stable isotope ratios allowed discrimination of specific feeding strategies during ontogenesis. Segregation between 5 cephalopod species in terms of trophic ecology was also evidenced (different isotopic niches). In contrast, Hg concentrations varied over the same order of magnitude in these 5 cephalopod species, despite higher levels in the benthic octopus Eledone cirrhosa. Consistently, Hg concentrations followed the same ontogenic pattern and increased with increasing body size/age of cephalopods. Finally, Cd concentrations varied over 3 orders of magnitude among the 5 species. Despite possible effects of physiology in terms of metal bioaccumulation, Cd concentrations were likely to reflect specific feeding preferences or feeding zones and ontogenic variability within a single species. Thus, ontogenic effects have to be taken into account when stable isotope ratios of carbon and nitrogen or trace metals are used as ecological tracers; the best recommendation being to focus on a given class age.

International audience

National audience

The identification of cephalopods using their beaks is still a difficult technique. To increase our knowledge of this technique and stimulate a new generation of beak experts, the III International beak workshop and training course was organized in Faial, Azores Islands in 2007. We briefly review the activities of the workshop, including the identification procedure of lower beaks of cephalopods from predators with emphasis on cetaceans, seals, fish and seabirds; provision of basic knowledge to young researchers interested in the study area; identification of recent developments in beak research; and discussion of the main problematic issues. The families that need particular attention are Brachioteuthidae, Chiroteuthidae, Cranchiidae, Cycloteuthidae, Mastigoteuthidae, Octopoteuthidae, Promachoteuthidae, Onychoteuthidae (particularly the genus Walvisteuthis), Mastigoteuthidae and Cirroteuthidae. The stable isotopic signature of beaks is capable of revealing new trophic relationships and migrations. Future work should focus on: a) obtaining more cephalopod material from research cruises; b) promoting a close and continuous collaboration between beak experts and cephalopod taxonomists and; c) developing new, and updated, beak guides.

The food and feeding ecology of the 2 closely related species of prions Pachyptila belcheri and P. desolata was investigated over 3 consecutive chick-rearing periods at Iles Kerguelen, the only place where they nest sympatrically in large numbers. In all years, the 2 prion species fed on crustaceans, with a small proportion of mesopelagic fish and squid. The hyperiid amphipod Themisto gaudichaudii was consistently the dominant prey item, accounting for 76 and 70% by number, and 57 and 57% by reconstituted mass of the diet of P. belcheri and P. desolata, respectively. Prions, however, were segregated by feeding on different euphausiids, P. belcheri on Thysanoessa sp. (18% by number and 16% by mass) and P. desolata on Euphausia vallentini (9% by number and 15% by mass). P. desolata also caught more small prey such as copepods (9 vs Lepas australis (8 vs 3% by number) than P. belcheri, which can be related to the beak filtering apparatus present only in the former species. Biogeography of the prey and their state of digestion indicate that prions foraged in a wide variety of marine habitats, including the kelp belt, kelp rafts, and coastal, neritic and oceanic waters. Noticeable is the occurrence of E. superba in a significant number of food samples (15 and 10% for P. belcheri and P. desolata, respectively), suggesting feeding in distant foraging grounds in southern Antarctic waters, >1000 km from the breeding colonies, during the chick-rearing period. The stable-carbon and -nitrogen isotopic compositions of chick feathers were identical in both species, indicating no important trophic segregation during the breeding period, when adult birds are central-place foragers. The ratios were, however, different in adult feathers, suggesting moulting in Antarctic waters for P. belcheri and in subtropical waters for P. desolata, i.e. in distinct foraging areas when birds are not constrained to return to the colonies.

The distribution of foraging activity for female Antarctic fur seals was investigated at Cap Noir (49° 07’ S, 70° 45’ E), Kerguelen Island in February 1998. Eleven females were fitted with a satellite transmitter and time-depth recorder. The 2 data sets were combined in order to locate diving activity of the seals. The occurrence of fish in the diet of the seals was investigated by the identification of otoliths in 55 scats collected at the breeding colony during the study period. Oceanographic variables were measured simultaneously by direct sampling and satellite remote sensing. The mesopelagic fish community was sampled at 20 stations along 4 transects, where epipelagic trawls were conducted at night at 50 m depth. We then investigated, using geographic information systems, the relationship between the spatial distribution of diving activity of the seals and oceanographic variables (sea surface temperature, surface chlorophyll concentration, prey distribution and bathymetry) at the same spatio-temporal scale. An inverse relationship was found between the main fish species preyed on by the fur seals and those sampled in trawl nets. However, diving activity of the seals was significantly related to oceanographic conditions, forage fish distribution and distance from the colony, although these relationships changed with the spatial scale investigated. A probabilistic model was developed for the distribution of diving activity, which predicted where females should concentrate their foraging activity according to the oceanographic conditions of the year, and where breeding colonies should be located.