Cedric Cotte

Muséum National d'Histoire Naturelle · Origines et Évolution

Multiple initiatives have called for large-scale representative networks of marine protected areas (MPAs). MPAs should be ecologically representative to be effective, but in large, remote regions this can be difficult to quantify and assess. We present a novel bioregionalization for the Southern Ocean, which uses the modelled circumpolar habitat im...

In the Southern Ocean, several zooplankton taxonomic groups, euphausiids, copepods, salps and pteropods, are notable because of their biomass and abundance and their roles in maintaining food webs and ecosystem structure and function, including the provision of globally important ecosystem services. These groups are consumers of microbes, primary a...

Aim Climate change will likely lead to a significant redistribution of biodiversity in marine ecosystems. We examine the potential redistribution of a community of marine predators by comparing current and future habitat distribution projections. We examine relative changes among species, indicative of potential future community-level changes and c...

Mesopelagic communities are characterized by a large biomass of diverse macrozooplankton and micronekton (MM) performing diel vertical migration (DVM) connecting the surface to the deeper ocean and contributing to biogeochemical fluxes. In the Southern Ocean, a prominent High Nutrient Low Chlorophyll (HNLC) and low carbon export region, the contrib...

Oceanic frontal zones have been shown to deeply influence the distribution of primary producers and, at the other extreme of the trophic web, top predators. However, the relationship between these structures and intermediate trophic levels is much more obscure. In this paper we address this knowledge gap by comparing acoustic measurements of mesope...

Campaign report of BIOSWOT-Med (spring 2023). PDF file available at : https://doi.org/10.13155/100060

The pelagic zone is home to a large diversity of organisms such as macrozooplankton and micronekton (MM), connecting the surface productive waters to the mesopelagic layers (200-1000 m) through diel vertical migrations (DVM). Active acoustics complement net sampling observations by detecting sound-scattering layers (SL) of organisms, allowing to mo...

Large-scale breeding failures, such as offspring die-offs, can disproportionately impact wildlife populations that are characterized by a few large colonies. However, breeding monitoring—and thus investigations of such die-offs—is especially challenging in species with long reproductive cycles. We investigate two unresolved dramatic breeding failur...

The Kerguelen Plateau is a region of natural iron fertilization in the Southern Ocean, within the typically iron limited High Nutrient Low Chlorophyll (HNLC) waters of the eastward flowing Antarctic Circumpolar Current. Between 26 February and 19 March 2018, the MOBYDICK expedition investigated pelagic ecosystem dynamics in the Kerguelen Island reg...

Southern Ocean ecosystems are globally important and vulnerable to global drivers of change, yet they remain challenging to study. Fish and squid make up a significant portion of the biomass within the Southern Ocean, filling key roles in food webs from forage to mid-trophic species and top predators. They comprise a diverse array of species unique...

Vertical distribution and size-dependent migrations of the pelagic tunicate Salpa thompsoni were studied during late summer to early autumn (26th February – 15th March 2018) at contrasting hydrological stations over the Kerguelen Plateau (Southern Indian Ocean). Vertical migrators, such as S. thompsoni, have potentially significant impacts on the b...

Understanding the factors that drive the dynamics of populations of long‐lived species presents a unique challenge for conservation management. Here we investigated long-term change in the body condition of adult northern rockhopper penguins Eudyptes moseleyi at Amsterdam Island, southern Indian Ocean, which hosts 5-10 % of the global population of...

Delord et al. Factors affecting adult body condition in the endangered northern rockhopper penguin. Mar Biol 168, 27 (2021) - Supplementary

This study aimed to obtain the first estimates of S. thompsoni population dynamics and growth rates over the Kerguelen Plateau (Southern Indian Ocean). Micronekton, including salps, were repeatedly sampled during late summer to early autumn (26th February – 15th March 2018) at contrasting hydrological stations on the Kerguelen Plateau in the southe...

The manuscript assesses the current and expected future global drivers of Southern Ocean (SO) ecosystems. Atmospheric ozone depletion over the Antarctic since the 1970s, has been a key driver, resulting in springtime cooling of the stratosphere and intensification of the polar vortex, increasing the frequency of positive phases of the Southern Annu...

The massive number of seabirds (penguins and procellariiformes) and marine mammals (cetaceans and pinnipeds) – referred to here as top predators – is one of the most iconic components of the Antarctic and Southern Ocean. They play an important role as highly mobile consumers, structuring and connecting pelagic marine food webs and are widely studie...

Distinguishing regions based on the geographic distribution of both abiotic factors and living organisms is an old but still actual central issue for biogeographers. In the Southern Ocean, the few existing regionalization studies have been carried out either at very large scales or on the relatively small region around the Sub-Antarctic islands of...

In the Antarctic Circumpolar Current region of the Southern Ocean, the massive phytoplankton blooms stemming from islands support large trophic chains. Contrary to islands, open ocean seamounts appear to sustain blooms of lesser intensity and, consequently, are expected to play a negligible role in the productivity of this area. Here we revisit thi...

There is a paucity of information on the foraging ecology, especially individual use of sea-ice features and icebergs, over the non-breeding season in many seabird species. Using geolocators and stable isotopes, we defined the movements, distribution and diet of adult Antarctic petrels Thalassoica antarctica from the largest known breeding colony,...

Oceanic Lagrangian Coherent Structures have been shown to deeply influence the distribution of primary producers and, at the other extreme of the trophic chain, top predators. However, the relationship between these structures and intermediate trophic levels is much more obscure. In this paper we address this knowledge gap by comparing acoustic mea...

Sub‐mesoscale fronts—with scales from 1 to 50 km are ubiquitous in satellite images of the world oceans. They are known to generate strong vertical velocities with significant impacts on biogeochemical fluxes and pelagic ecosystems. Here, we use a unique data set, combining high‐resolution behavioral and physical measurements, to determine the effe...

Results acquired over more than two decades now make it possible to outline the functioning of the pelagic ecosystem off the Kerguelen Islands. Although the structuring role of natural iron fertilization has been demonstrated both in terms of productivity and the structuring of pelagic communities, recent results raise questions about the paradigm...

The MOBYDICK program runs from 2017 to 2021. The major milestone has been the oceanographic cruise, which took place from 18 February to 27 March 2018 in the Indian sector of the Southern Ocean, off the Kerguelen Islands, onboard the N.O. Marion Dufresne. The MOBYDICK team studies end-to-end food webs in contrasted environments under HNLC context i...

The Southern Ocean is a major component of the Earth system undergoing rapid transitions due to global change. With regards to the CO 2 problem, part of the response of the Earth system is controlled by the oceanic biological carbon pump, which is responsible for establishing the pCO 2 gradient between atmosphere and surface waters, while being als...

Satellite data analysis has showed that the environment of the open ocean – uniform and homogeneous to our naked eyes - is in fact populated by strongly contrasted physical features, whose lifetime occurs on ecologically relevant spatial and temporal scales. This dynamical landscape has a primary structuring role on marine ecosystems in particular...

Compared to ecosystem conservation in territorial seas, protecting the open ocean has peculiar geopolitical, economic and scientific challenges. One of the major obstacle is defining the boundary of an open ocean Marine Protected Area (MPA). In contrast to coastal ecosystems, which are mostly constrained by topographic structures fixed in time, the...

Despite its ecological importance, micronekton remains one of the least investigated components of the open-ocean ecosystems. Our main goal was to characterize micronektonic organisms using bi-frequency acoustic data (38 and 120 kHz) by calibrating an algorithm tool that discriminates groups of scatterers in the top 300 m of the productive oceanic...

It is well recognized that most marine vertebrates, and especially tetrapods, precisely orient and actively move in apparently homogeneous oceanic environments. Here, we investigate the presumptive role of oceanic currents in biogeographic patterns observed in a secondarily marine tetrapod, the yellow-bellied sea snake ( Hydrophis [ Pelamis ] platu...

Micronelcton constitutes the largest unexploited marine biomass worldwide. It is one of the most conspicuous and ecologically important components of the still poorly known mesopelagic ecosystem. Acoustic data were collected from both fishing and research vessels along 18 transects for a total of 47 682 linear kilometers to investigate large-scale...

Micronektonconstitutesthelargestunexploitedmarinebiomassworldwide.Itisoneofthemostcon-spicuous andecologicallyimportantcomponentsofthestillpoorlyknownmesopelagicecosystem.Acoustic datawerecollectedfromboth fishing andresearchvesselsalong18transectsforatotalof47682linearkilometerstoinvestigatelarge-scaledistributionofmicronektonoveralonglatitudinalg...

Seabirds are considered to be good indicators of the marine environment. However, little is known about the effects of environmental variability on the foraging behaviour of tropical seabirds. Red-footed boobies (RFB) nesting on Europa Island (Mozambique Channel) were fitted with GPS devices over four years and different breeding stages. We first s...

While resource acquisition strategies of marine predators are well studied in polar and temperate environments, far less is known in tropical marine environments. Tropical waters are characterised by a low productivity, a low seasonality, and in some areas a high interannual variability due to climatic events such as El Niño and La Niña. Due to the...

Determining the links between the behavioural and population responses of wild species to environmental variations is critical for understanding the impact of climate variability on ecosystems. Using long-term data sets, we show how large-scale climatic anomalies in the Southern Hemisphere affect the foraging behaviour and population dynamics of a...

Field campaigns are instrumental in providing ground truth for understanding and modeling global ocean biogeochemical budgets. A survey however can only inspect a fraction of the global oceans, typically a region hundreds of kilometers wide for a temporal window of the order of (at most) several weeks. This spatiotemporal domain is also the one in...

In this work scientific echosounder were used hull mounted onboard R/V Marion Dufresne II to scrutinize the vertical distribution of micronekton according to water masses characteristics along transect which were discriminated with spatial remote sensing data. Acoustic data were collected continuously at 38 kHz frequency during eighteen transits ca...

While resource acquisition strategies of marine predators are well studied in polar and temperate environments, far less is known in tropical marine environments that are, in comparison, less productive. Here we study the influence of various environmental variables on the habitat and foraging behaviour of a pan-tropical species: the red-footed boo...

Field campaigns are instrumental in providing ground truth for understanding and modelling global ocean biogeochemical budgets. A survey however can only inspect a fraction of the global oceans, typically a region 100s km wide for a temporal window of the order of (at most) several weeks. This spatiotemporal domain is also the one in which the meso...

The circulation of iron-rich shelf waters around the Kerguelen Islands plays a crucial role for a climatically important, annually-recurrent phytoplankton spring bloom over the sluggish shelf region and its downstream plume area along the Antarctic circumpolar flow. However, there is a long-standing confusion about the Polar Front (PF) in the Kergu...

The repartition of tracers in the ocean's upper layer on the scale of a few tens of kilometres is largely determined by the horizontal transport induced by surface currents. Here we consider surface currents detected from satellite altimetry (Jason and Envisat missions) and we study how surface waters may be trapped by mesoscale eddies through a se...

In situ observation of the marine environment has traditionally relied on ship-based platforms. The obvious consequence is that physical and biogeochemical properties have been dramatically undersampled, especially in the remote Southern Ocean (SO). The difficulty in obtaining in situ data represents the major lim- itations to our understanding, an...

Marine top predators such as seabirds are useful indicators of the integrated response of the marine ecosystem to environmental variability at different scales. Large-scale physical gradients constrain seabird habitat. Birds however respond behaviourally to physical heterogeneity at much smaller scales. Here, we use, for the first time, three-dimen...

In-situ observation of the marine environment has traditionally relied on ship-based platforms. The obvious consequence is that physical and biogeochemical properties have been dramatically undersampled, especially in the remote Southern Ocean (SO). The difficulty in obtaining in situ data represents the major limitations to our understanding, and...

During their journeys, seabirds are faced to environmental heterogeneity of the scale of tens of Kms in extension and of days in duration, that are induced in the open ocean by mesoscale and submesoscale turbulence. We combine tracking of frigatebirds in the Mozambique channel - available for the first time with 3-D resolution - and multisatellite-...

Humpback whale populations in the Southern Hemisphere were dramatically reduced by the whaling industry. A comprehensive whaling dataset was used in an analysis of circumpolar abundance of humpback whale catches relative to contemporary densities of its preferred prey, Antarctic krill, and to a major dynamic feature of the marine ecosystem, the sum...

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 t...

We investigated the influence of the ocean circulation at different spatiotemporal scales on the seasonal distribution of a large marine predator, the Mediterranean fin whale, by comparing multisatellite data with the positions of eight fin whales equipped with Argos tracking devices from August 2003 to June 2004. At the western Mediterranean basin...

Although the striped dolphin Stenella coeruleoalba has a world status of Least Concern, a recent IUCN Red List assessment has proposed that the Mediterranean population be listed as Vulnerable and stresses the need for an estimate of abundance and distribution. While substantial efforts have been made to study cetaceans in regions of the western Me...

Incidental seabird mortality associated with longline commercial fishing is a worldwide conservation concern. To develop conservation strategies, it is essential to estimate the likelihood of seabird bycatch and the degree of overlap between birds' foraging grounds and commercial fishing areas. We tracked 21 adult white-chinned petrels Procellaria...

Physical processes, such as mesoscale eddies, play an important role in ocean mixing and concentrating biological productivity, which provides great feeding opportunities for many marine top predators. This study describes the presumed foraging behaviour of southern elephant seals Mirounga leonina within an intense eddy field along the Polar Front...

Since the heterogeneity of oceanographic conditions drives abundance, distribution, and availability of prey, it is essential to understand how foraging predators interact with their dynamic environment at various spatial and temporal scales. We examined the spatio-temporal relationships between oceanographic features and abundance of fin whales (B...

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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 t...

In their recent review article “Paradigm lost, or is top-down forcing no longer significant in the Antarctic marine ecosystem?” Ainley et al. (2007) questioned why Southern Ocean marine ecologists apparently have shifted to a central paradigm where bottom-up forcing by physics and climate change has become the single most important driver of food w...

Despite increasing evidence that marine predators associate with mesoscale eddies, how these marine features influence foraging movements is still unclear. This study investigates the relationship of at-sea movements of king penguins to mesoscale eddies using oceanographic remote sensing and movement data from 43 individual trips over 4 years. Simu...