CITATIONS 0 READS 40 6 authors, including: Some of the authors of this publication are also worki... more CITATIONS 0 READS 40 6 authors, including: Some of the authors of this publication are also working on these related projects: Foraging behaviour of the Red-footed booby View project IceBird -Response of Antarctic seabirds to a changing environment: from oceanographic conditions to foraging behaviour and demography View project Cedric Cotte Muséum National d'Histoire Naturelle
The open ocean is a highly variable environment where marine top predators are thought to require... more The open ocean is a highly variable environment where marine top predators are thought to require optimized foraging strategies to locate and capture prey. Mesoscale and sub-mesoscale features are known to effect planktonic organisms but the response of top predators to these features results from behavioural choices and is poorly understood. Here, we investigated a multi-year database of at-sea distribution and behaviour of female Southern elephant seals (Mirounga leonina) to identify their preference for specific structures within the intense eddy field of the dynamic Antarctic Circumpolar Current (ACC). We distinguished two behavioural modes, i.e. travelling and intensive foraging, using state-space modelling. We employed multisatellite Lagrangian diagnostics to describe properties of (sub-)mesoscale oceanic circulation. Statistical analyses (GAMMs and Student's t-tests) revealed relationships between elephant seal behaviour and (sub-)mesoscale features during the post-moulting period (January-August): travelling along thermal fronts and intensive foraging in cold and long-lived mesoscale water patches. A Lagrangian analysis suggests that these water patches -where the prey field likely developed and concentrated -corresponded to waters which have supported the bloom during spring. In contrast, no clear preference emerged at the (sub-)mesoscale during the post-breeding period (October-December), although seals were distributed within the Chlorophyll-rich water plume detaching from the plateau. We interpret this difference in terms of a seasonal change in the prey field. Our interdisciplinary approach contributes to elucidate the foraging strategies of top predators in a complex and dynamic environment. It also brings top down insights on prey distribution in remote areas where information on mid-trophic levels are strongly lacking and it identifies important physical-biological interactions relevant for ecosystem modelling and management.
Incidental mortality of seabirds on fishing vessels is well docu-mented and there is mounting evi... more Incidental mortality of seabirds on fishing vessels is well docu-mented and there is mounting evidence that longline fishing is a major cause of observed decrease of albatross and petrel popula-tions (Brothers, 1991). interactions with fishery activities often have lethal consequences and assessing the magnitude of these potential interactions is therefore a priority. the Commission for the Conservation of Antarctic marine living resources (CCAm-lr), the Agreement on the Conservation of Albatross and Petrels (ACAP), the southern indian ocean Fisheries Agreement (sioFA), and BirdLife International thus recommend a better identification of overlapping areas between seabirds and fisheries, and an assess-ment of interactions likely to induce incidental mortality on as fine a spatio-temporal scale as possible. this can be achieved through the use of remote telemetry to identify seabird distributions, along with data on the distribution of commercial fishing effort (Weim-erskirch, 1998) t...
During the last 30 years, at-sea studies of seabirds and marine mammals in the oceans south of th... more During the last 30 years, at-sea studies of seabirds and marine mammals in the oceans south of the Subtropical Front have described an association with major frontal areas. More recently, the advancement in microtechnology has allowed the tracking of individuals and investigations into how these marine predators actually use the frontal zones. In this review, we examine 1) the relative importance to apex predators of the different frontal zones in terms of spatial distribution and carbon flux; 2) the processes that determine their preferential use; and 3) how the mesoscale dynamics of frontal structures drive at-sea foraging strategies of these predators. We review published results from southern waters and place them in a broader context with respect to what has been learned about the importance of fronts in oceans farther north. Some fronts constitute important boundaries for seabird communities in southern waters. At a mesoscale the maximum values of seabird diversity and abundance correspond to the location of the main fronts. At-sea surveys show a strong curvilinear correlation between seabird abundance and sea surface temperatures. High mean species richness and diversity for whales and seabirds are consistently associated with the southern water mass boundary of the Antarctic Circumpolar Current, the Subtropical Front and the Subantarctic Front; in the case of the Polar Front mean seabird densities are more variable. At small-scales, variation in seabird occurrence has been directly related to the processes at fronts in a limited number of cases. A significant positive relation was found between some plankton feeding species and frontal temperature gradient-phytoplankton variables. Telemetric studies have revealed that several apex predators (penguins, albatrosses, seals) perform long, directed foraging trips either to the Subtropical front or Polar Front, depending on locality. Seabirds with low flight costs, such as albatrosses, are able to reach fronts at long distances from colonies, showing variable foraging strategies as a function of the distances involved. Diving birds such as King penguins, that travel at a higher cost and lower speed, rely on the predictable spatial distribution of mesopelagic fish found close to the Polar Front. They may use the currents associated with eddies as oceanographic cues in the active search for frontal zones. Once in these areas they dive preferentially in and below the depth of the thermocline where catches per unit effort are high. Elephant seals concentrate foraging activity principally inside or at the boundary of cyclonic eddies. These mesoscale features appear to offer exceptional productivity favourable for foraging by various diving top predators. The connection between biophysical parameters at fronts and predators is likely to be made through biological enhancement. Top predators appear to forage at locations where prey are advected by physical processes and others where prey are produced locally. Long-term research on at-sea distributions and demographic parameters of top predators are essential to assess the consequences of potential shift in front distributions in relation to global warming. Such environmental changes would add to the impact of fish extraction by the industrial fisheries on the southern food webs.
... Delord1,*, Cédric Cotté1, Clara Péron1, Cédric Marteau1, 3, Patrice Pruvost2, Nicolas Gasco2,... more ... Delord1,*, Cédric Cotté1, Clara Péron1, Cédric Marteau1, 3, Patrice Pruvost2, Nicolas Gasco2, Guy Duhamel2, Yves Cherel1, Henri Weimerskirch1 1Centre d'Études Biologiques de Chizé, UPR 1934 du Centre National de la Recherche Scientifique, 79360 Villiers-en-Bois, ...
CITATIONS 0 READS 40 6 authors, including: Some of the authors of this publication are also worki... more CITATIONS 0 READS 40 6 authors, including: Some of the authors of this publication are also working on these related projects: Foraging behaviour of the Red-footed booby View project IceBird -Response of Antarctic seabirds to a changing environment: from oceanographic conditions to foraging behaviour and demography View project Cedric Cotte Muséum National d'Histoire Naturelle
The open ocean is a highly variable environment where marine top predators are thought to require... more The open ocean is a highly variable environment where marine top predators are thought to require optimized foraging strategies to locate and capture prey. Mesoscale and sub-mesoscale features are known to effect planktonic organisms but the response of top predators to these features results from behavioural choices and is poorly understood. Here, we investigated a multi-year database of at-sea distribution and behaviour of female Southern elephant seals (Mirounga leonina) to identify their preference for specific structures within the intense eddy field of the dynamic Antarctic Circumpolar Current (ACC). We distinguished two behavioural modes, i.e. travelling and intensive foraging, using state-space modelling. We employed multisatellite Lagrangian diagnostics to describe properties of (sub-)mesoscale oceanic circulation. Statistical analyses (GAMMs and Student's t-tests) revealed relationships between elephant seal behaviour and (sub-)mesoscale features during the post-moulting period (January-August): travelling along thermal fronts and intensive foraging in cold and long-lived mesoscale water patches. A Lagrangian analysis suggests that these water patches -where the prey field likely developed and concentrated -corresponded to waters which have supported the bloom during spring. In contrast, no clear preference emerged at the (sub-)mesoscale during the post-breeding period (October-December), although seals were distributed within the Chlorophyll-rich water plume detaching from the plateau. We interpret this difference in terms of a seasonal change in the prey field. Our interdisciplinary approach contributes to elucidate the foraging strategies of top predators in a complex and dynamic environment. It also brings top down insights on prey distribution in remote areas where information on mid-trophic levels are strongly lacking and it identifies important physical-biological interactions relevant for ecosystem modelling and management.
Incidental mortality of seabirds on fishing vessels is well docu-mented and there is mounting evi... more Incidental mortality of seabirds on fishing vessels is well docu-mented and there is mounting evidence that longline fishing is a major cause of observed decrease of albatross and petrel popula-tions (Brothers, 1991). interactions with fishery activities often have lethal consequences and assessing the magnitude of these potential interactions is therefore a priority. the Commission for the Conservation of Antarctic marine living resources (CCAm-lr), the Agreement on the Conservation of Albatross and Petrels (ACAP), the southern indian ocean Fisheries Agreement (sioFA), and BirdLife International thus recommend a better identification of overlapping areas between seabirds and fisheries, and an assess-ment of interactions likely to induce incidental mortality on as fine a spatio-temporal scale as possible. this can be achieved through the use of remote telemetry to identify seabird distributions, along with data on the distribution of commercial fishing effort (Weim-erskirch, 1998) t...
During the last 30 years, at-sea studies of seabirds and marine mammals in the oceans south of th... more During the last 30 years, at-sea studies of seabirds and marine mammals in the oceans south of the Subtropical Front have described an association with major frontal areas. More recently, the advancement in microtechnology has allowed the tracking of individuals and investigations into how these marine predators actually use the frontal zones. In this review, we examine 1) the relative importance to apex predators of the different frontal zones in terms of spatial distribution and carbon flux; 2) the processes that determine their preferential use; and 3) how the mesoscale dynamics of frontal structures drive at-sea foraging strategies of these predators. We review published results from southern waters and place them in a broader context with respect to what has been learned about the importance of fronts in oceans farther north. Some fronts constitute important boundaries for seabird communities in southern waters. At a mesoscale the maximum values of seabird diversity and abundance correspond to the location of the main fronts. At-sea surveys show a strong curvilinear correlation between seabird abundance and sea surface temperatures. High mean species richness and diversity for whales and seabirds are consistently associated with the southern water mass boundary of the Antarctic Circumpolar Current, the Subtropical Front and the Subantarctic Front; in the case of the Polar Front mean seabird densities are more variable. At small-scales, variation in seabird occurrence has been directly related to the processes at fronts in a limited number of cases. A significant positive relation was found between some plankton feeding species and frontal temperature gradient-phytoplankton variables. Telemetric studies have revealed that several apex predators (penguins, albatrosses, seals) perform long, directed foraging trips either to the Subtropical front or Polar Front, depending on locality. Seabirds with low flight costs, such as albatrosses, are able to reach fronts at long distances from colonies, showing variable foraging strategies as a function of the distances involved. Diving birds such as King penguins, that travel at a higher cost and lower speed, rely on the predictable spatial distribution of mesopelagic fish found close to the Polar Front. They may use the currents associated with eddies as oceanographic cues in the active search for frontal zones. Once in these areas they dive preferentially in and below the depth of the thermocline where catches per unit effort are high. Elephant seals concentrate foraging activity principally inside or at the boundary of cyclonic eddies. These mesoscale features appear to offer exceptional productivity favourable for foraging by various diving top predators. The connection between biophysical parameters at fronts and predators is likely to be made through biological enhancement. Top predators appear to forage at locations where prey are advected by physical processes and others where prey are produced locally. Long-term research on at-sea distributions and demographic parameters of top predators are essential to assess the consequences of potential shift in front distributions in relation to global warming. Such environmental changes would add to the impact of fish extraction by the industrial fisheries on the southern food webs.
... Delord1,*, Cédric Cotté1, Clara Péron1, Cédric Marteau1, 3, Patrice Pruvost2, Nicolas Gasco2,... more ... Delord1,*, Cédric Cotté1, Clara Péron1, Cédric Marteau1, 3, Patrice Pruvost2, Nicolas Gasco2, Guy Duhamel2, Yves Cherel1, Henri Weimerskirch1 1Centre d'Études Biologiques de Chizé, UPR 1934 du Centre National de la Recherche Scientifique, 79360 Villiers-en-Bois, ...
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