Frédéric Ménard

• Senior Researcher at French National Research Institute for Sustainable Development

Trophic links between the epipelagic (< 200 m) and mesopelagic layers of the Indian Ocean were investigated by carbon and nitrogen stable isotope ratios of 2405 samples collected from 2002 to 2016, and that encompass the base of trophic webs, and primary, secondary and tertiary consumers. The samples include particulate organic matter, gastropods,...

ABSTRACT: Humans are exposed to toxic methylmercury mainly by consuming marine fish. While reducing mercury emissions and releases aims to protect human health, it is unclear how this affects methylmercury concentrations in seawater and marine biota. We compiled existing and newly acquired mercury concentrations in tropical tunas from the global oc...

Fishers have intensively used drifting fish aggregating devices (DFADs) over the last three decades to facilitate their catch of tropical tunas. DFADs increase purse‐seine efficiency, potentially increasing tuna fishing mortality. They could also have impacts on tuna natural mortality and reproductive potential, and assessing the consequences of th...

The large‐scale proliferation of pelagic Sargassum in the Tropical Atlantic from 2011 has been the subject of increasing attention because of its negative consequences on the environment, fishing, and socioeconomic activities when stranding on coastal areas. This recurrent phenomenon presents strong seasonal and year to year variations. Anticipatin...

The present study reports the concentration of HgT and MeHg in sediments and food webs in estuarine and coastal areas of Northeast Brazil, which have been subject to different impacts, mainly by chlorine and alkali companies. The results showed that the HgT in the sediment varied from 1.7 to 1186 ng g−1 and from 3.3 to 2163 ng g−1 in the organisms....

ABSTRACT - Understanding the ecological mechanisms underpinning species distribution patterns is vital in managing populations of mobile marine species. This study is a first step towards an integrated description of the habitats and spatial distributions of marine predators in the Natural Park of the Coral Sea, one of the world’s largest marine pr...

The connection between epipelagic and deep-sea mesopelagic realms controls a variety of ecosystem processes including oceanic carbon storage and the provision of harvestable fish stocks. So far, these two layers have been mostly addressed in isolation and the ways they connect remain poorly understood. Furthermore, both systems are affected by clim...

Plastic debris is ubiquitous in the hydrosphere. Yet, we lack an understanding of contamination among deep-sea species and primarily how each trait can influence microplastic intake. We investigated microplastic contamination in the digestive tract of hyper-abundant mesopelagic lanternfishes from the Southwestern Tropical Atlantic, captured from 90...

The ocean has recently taken centre stage in the global geopolitical landscape. Despite rising challenges to the effectiveness of multilateralism, attention to ocean issues appears as an opportunity to co-create pathways to ocean sustainability at multiple levels. The ocean science community, however, is not sufficiently well organised to advance t...

A trophic web is a network of complex interactions and energy links between species. These interactions can be simplified into trophodynamic models, such as Ecopath (EP) and EcoTroph (ET), important tools providing the holistic view needed for the ecosystem approach to fisheries. We describe food web structure and trophic interactions by developing...

The lack of knowledge about highly anthropised tropical ecosystems poses a problem for their conservation. Using carbon and nitrogen stable isotopes, we studied the food web structure of the estuarine ecotone of the Santa Cruz Channel (SCC), which constitutes a critical habitat for many socio-economically important species in northeast Brazil. Ther...

Understanding the ecological mechanisms underpinning distribution patterns is vital in managing populations of mobile marine species. This study is a first step towards an integrated description of the habitats and spatial distributions of marine predators in the Natural Park of the Coral Sea, one of the world’s largest marine-protected areas at ab...

Faced with sea level rise and the intensification of extreme events, human populations living on the coasts are developing responses to address local situations. A synthesis of the literature on responses to coastal adaptation allows us to highlight different adaptation strategies. Here, we analyze these strategies according to the complexity of th...

Lanternfishes (Myctophidae) are among the most abundant, widespread, and diverse fish groups in the world ocean. They account for a significant part of oceanic fish biomass and play crucial roles in various ecosystem processes, including carbon sequestration and nutrient recycling. However, despite the increasing risks they face (e.g. global warmin...

The tropical Atlantic has been facing a massive proliferation of Sargassum since 2011, with severe environmental and socioeconomic impacts. The development of large-scale modeling of Sargassum transport and physiology is essential to clarify the link between Sargassum distribution and environmental conditions, and to lay the groundwork for a season...

Ecosystem models forced by future climate simulations outputs from the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulate a substantial decline of tropical marine animal biomass over the course of the 21st century. Regional projections are however far more uncertain because of well-known biases common to most CMIP5 historical simulation...

Jacks are highly prized tropical marine fish. Most of them complete their whole life cycle at sea but some use estuaries at the juvenile stage before moving back to coastal waters and joining the adult exploited stocks. Little is known about jacks’ trophic ecology in estuaries, although their juveniles' ability to successfully exploit available res...

The Tropical Atlantic is facing a massive proliferation of Sargassum since 2011, with severe environmental and socioeconomic impacts. As a contribution to this proliferation, an increase in nutrient inputs from the tropical rivers, in response to climate and land use changes or increasing urbanization, has been often suggested and widely reported i...

We used complementary stable isotope (SIA) and stomach content (SCA) analyses to investigate feeding relationships among species of the nektobenthic communities and the potential ecological effects of the bottom trawling of a coastal ecosystem in northeastern Brazil. Carbon (δ¹³C) and nitrogen (δ¹⁵N) compositions were determined for five basal sour...

Nitrogen and carbon stable isotope data sets are commonly used to assess complex population to ecosystem responses to natural or anthropogenic changes at regional to global spatial scales, and monthly to decadal timescales. Measured in the tissues of consumers, nitrogen isotopes (δ¹⁵N) are primarily used to estimate trophic position while carbon is...

Average Sargassum beaching distribution after one year of drift.

The Tropical Atlantic is facing a massive proliferation of Sargassum since 2011, with severe environmental and socioeconomic impacts. The development of Sargassum modelling is essential to clarify the link between Sargassum distribution and environmental conditions, and to lay the groundwork for a seasonal forecast on the scale of the Tropical Atla...

Mesopelagic fishes are numerically the most important vertebrate group of all world’s oceans. While these species are increasingly threatened by anthropogenic activities, basic biological knowledge is still lacking. For instance, major uncertainties remain on the behaviour, ecology, and thus functional roles of mesopelagic micronektivores, particul...

Since 2011, huge amounts of Sargassum algae are detected in the equatorial Atlantic, causing large strandings events on the coasts of the West Indies, Brazil and West Africa. The distribution of this stock shows strong annual and interannual variability, whose drivers are not settled yet. Here we use satellite Sargassum observations from MODIS and...

Mesopelagic resources are central to the ecosystem but remain poorly studied mainly due to the lack of observations. This paper investigates the assemblages of micronekton organisms and their habitat in the Natural Park of the Coral Sea around New Caledonia (southwest Pacific) using data from 141 pelagic trawls. A total of 67,130 micronekton indivi...

An investigation of the vertical and horizontal distributions of micronekton, as influenced by mesoscale eddies, the Madagascar shelf and shallow seamounts, was undertaken using acoustic data collected during two research cruises at an unnamed pinnacle (summit depth ~240 m) thereafter named “MAD-Ridge”, and at La Pérouse seamount (~60 m) in the sou...

The stable carbon (δ13C) and nitrogen (δ15N) isotope values of soft tissues of micronekton (crustaceans, squid, mesopelagic fish) and zooplankton were measured from organisms collected on the RV Antea at two seamounts located in the south-western Indian Ocean: La Pérouse (summit depth ~60 m) and “MAD-Ridge” (thus named in this study; summit depth ~...

Species of the family Sternoptychidae (hatchetfishes) occur worldwide and play critical roles by sequestering carbon, recycling nutrients, and acting as a key trophic link between epipelagic primary consumers and higher trophic levels in marine ecosystems. Nevertheless, basic knowledge on their ecology is still lacking and their functional ecology...

Owing to difficulties in accessing the vast open ocean, the beta (β) diversity of pelagic fish assemblages remains poorly studied. We investigated the relationship between assemblage similarity and geographical distance between anchored fish aggregating devices (FADs), sampled by standardised underwater visual censuses in three anchored FAD arrays...

A global dataset of carbon stable isotope (δ13C) values from yellowfin, bigeye, and albacore tuna muscle tissue (n = 4275) was used to develop a novel tool to infer broad-scale movement and residency patterns of these highly mobile marine predators. This tool was coupled with environmental models and lipid content (C:N ratio) of tuna muscle tissues...

Taxonomic composition, abundance and biological features of micronektonic fish were investigated using pelagic trawls conducted near and over the summits of three seamounts located in the western Indian Ocean (La Pérouse, MAD-Ridge and Walters Shoal). Mesopelagic fish from three families accounted for 80% by number of the total catch (5714 specimen...

Acoustic data are invaluable information sources for characterizing the distribution and abundance of mid-trophic-level organisms (micronekton). These organisms play a pivotal role in the ecosystem as prey of top predators and as predators of low-trophic-level organisms. Although shipboard-ADCP (acoustic Doppler current profiler) acoustic backscatt...

Tetraodontiformes fishes play a critical role in benthic and demersal communities and are facing threats due to anthropogenic impacts and climate change. However, they are poorly studied worldwide. To improve knowledge on the socio‐ecological significance and conservation of Tetraodontiformes a review of literature addressing the diversity, ecology...

There is a growing interest in the management of seamounts of the Southwestern Indian Ocean (SWIO) both in waters under national jurisdictions and in the Areas Beyond National Jurisdiction (ABNJ). New scientific knowledge has been gathered through various oceanographic cruises during the past decade, and new agreements are under consideration globa...

The health of the ocean, central to human well-being, has now reached a critical point. Most fish stocks are overexploited, climate change and increased dissolved carbon dioxide are changing ocean chemistry and disrupting species throughout food webs, and the fundamental capacity of the ocean to regulate the climate has been altered. However, key t...

Considerable uncertainty remains over how increasing atmospheric CO2 and anthropogenic climate changes are affecting open‐ocean marine ecosystems from phytoplankton to top predators. Biological time series data are thus urgently needed for the world's oceans. Here, we use the carbon stable isotope composition of tuna to provide a first insight into...

Acoustic data are an invaluable source of information for characterizing the distribution and abundance of mid-trophic level organisms (MTLOs) in the ocean. These organisms play a key role in the ecosystem as prey of top predators and as predators of lower trophic level organisms, as well as in carbon export from the surface into deeper waters. Thi...

The present study reports on observations carried out in the Tropical North Atlantic in summer and autumn 2017, documenting Sargassum aggregations using both ship-deck observations and satellite sensor observations at three resolutions (MSI-10 m, OLCI-300 m, VIIRS-750 m and MODIS-1 km). Both datasets reported that in summer, Sargassum aggregations...

Micronekton distributions and assemblages were investigated at two shallow seamounts of the south-western Indian Ocean using a combination of trawl data and a multi-frequency acoustic visualisation technique. La Pérouse seamount (summit depth ~60 m) is located on the outskirts of the oligotrophic Indian South Subtropical Gyre (ISSG) province with w...

We investigated the trophic niches and the resource partitioning of two snook species, the common (Centropomus undecimalis) and the fat snook (C. parallelus), in four tropical estuaries of the northeastern Brazil, using stable isotope analyses of carbon (δ13C) and nitrogen (δ15N). Fish specimens, mainly juveniles, basal resources and a primary cons...

Ecological guilds have been widely applied for understanding the structure and functioning of aquatic ecosystems. This study describes the composition and the spatio-temporal changes in the structure of the fish fauna and the movements between the estuary and the coast of a tropical estuary, the Itapissuma/Itamaracá Complex (IIC) in northeastern Br...

In an ecosystem approach to fisheries management (EAFM) framework of the tuna purse-seine fishery, the assessment of target species, but also that of bycatch species, is essential. In the Atlantic and Indian oceans, purse-seine nets are sometimes set around tuna schools associated with whale sharks and baleen whales, although less frequently than a...

This study provides the length‐weight relationship (LWR) for 13 demersal fish species belonging to 11 families and 8 orders. Data were collected in the northeast Brazilian continental shelf during two scientific surveys (2015 and 2017) using a bottom trawl net (side length of body mesh: 40 mm, side length of cod‐end mesh: 25 mm) at 35 stations betw...

Aim We examined potential environmental drivers of broad‐scale spatial patterns in the trophic structure of marine ecosystems as represented by nitrogen stable isotopes in globally distributed marine predators. Additionally, we assessed the effects of spatial scale on the predictive capabilities of environmental variables. Location Global oceans....

Knowledge of the spatial distribution of fish assemblages biodiversity and structure is essential for prioritizing areas of conservation. Here we describe the biodiversity and community structure of demersal fish assemblages and their habitat along the northeast Brazilian coast by combining bottom trawl data and underwater footage. Species composit...

We study a fully trait-based size-structured population model, with a few number of species. The goal is to bring elements of understanding and isolate some processes that may lead to brutal modifications of the structure and/or dynamics of this simplified food web, and to compare it to real cases in marine ecology. In a broader context, we aim at...

Sharks are a diverse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fi...

Vulnerability of inter-tropical littoral areas

The northern Humboldt Current system (NHCS) is the most productive eastern boundary upwelling system (EBUS) in terms of fish productivity despite having a moderate primary production compared with other EBUS. To understand this apparent paradox, an updated vision of the trophic relationships in the NHCS is required. Using δ¹³C and δ¹⁵N as a proxy o...

Predator-prey interactions for three commercially valuable tuna species: yellowfin (Thunnus albacares), bigeye (T. obesus), and albacore (T. alalunga), collected over a 40-year period from the Pacific, Indian, and Atlantic Oceans, were used to quantitatively assess broad, macro-scale trophic patterns in pelagic ecosystems. Analysis of over 14,000 t...

Les océans jouent un rôle crucial pour la sécurité alimentaire mondiale, la régulation climatique, le cycle de l'eau et de nombreux autres services écosystémiques. L'ODD 14 entend conserver et exploiter de manière durable les océans, les mers et les ressources marines aux fins du développement durable. Cet Objectif devra se réaliser en articulant l...

The silky shark Carcharhinus falciformis is commonly associated with floating objects, including fish aggregating devices (FADs), in the Indian Ocean. While the motives for this associative behaviour are unclear, it does make them vulnerable to capture in the tuna purse seine fishery that makes extensive use of FADs. Here, the diet of 323 C. falcif...

The presently reported study provides length-weight relations (LWR) of 70 fish species (Actinopterygii) from the tropical coastal region of Pernambuco, Northeast Brazil: Achirus declivis, Achirus lineatus, Anchoa spinifer, Anchoa tricolor, Anchovia clupeoides, Archosargus rhomboidalis, Aspistor luniscutis, Aspistor quadriscutis, Bagre bagre, Bagre...

Small pelagic fish are among the most ecologically and economically important marine fish species and are characterized by large fluctuations all over the world. In the Mediterranean Sea, low catches and biomass of anchovies and sardines have been described in some areas during the last decade, resulting in important fisheries crises. Therefore, we...

Limited resources in the environment prevent individuals from simultaneously maximizing all life-history traits, resulting in trade-offs. In particular, the cost of reproduction is well known to negatively affect energy investment in growth and maintenance. Here, we investigated these trade-offs during contrasting periods of high versus low fish si...

Given the ecological importance and high socioeconomic value of the fishery of the Gulf of Gabes, an end-to-end model was applied to its continental shelf ecosystem to characterize the structure of the food web in the 2000s. This approach consisted in forcing a high trophic level model (OSMOSE) with an existing biogeochemical model (Eco3M-MED) repr...

Tunas are highly specialized predators that have evolved numerous adaptations for a lifestyle that requires large amounts of energy consumption. Here we review our understanding of the bioenergetics and feeding dynamics of tunas on a global scale, with an emphasis on yellowfin, bigeye, skipjack, albacore, and Atlantic bluefin tunas. Food consumptio...

Marine fisheries have a direct impact on the resources they exploit but also indirectly affect other species, habitats and the way ecosystems work. Ecosystem approach to fisheries (EAF) is a major aspect for the exploitation of marine resources and conservation of species. An ecosystem is set formed by a community of living beings and their biologi...

Since 2008, a severe decrease in size and body condition together with a demographic truncation has been observed in sardine (secondarily in anchovy) population of the Gulf of Lions (NW Mediterranean Sea). In parallel, sprat biomass, which was negligible before, has increased tenfold. All these changes have strongly affected the regional fisheries....

This study examined the trophic ecology of three sympatric tropical tuna species (bigeye BET, skipjack SKJ, and yellowfin YFT) sampled in the Western Indian Ocean throughout 2013. Specifically we explored inter-specific resource partitioning and ontogenetic variability using neutral fatty acids and stable isotope analysis of liver and muscle from s...

The presently reported study provides length-weight relations (LWR) of 70 fish species (Actinopterygii) from the tropical coastal region of Pernambuco, Northeast Brazil: Achirus declivis, Achirus lineatus, Anchoa spinifer, Anchoa tricolor, Anchovia clupeoides, Archosargus rhomboidalis, Aspistor luniscutis, Aspistor quadriscutis, Bagre bagre, Bagre...

The feeding strategy of female yellowfin tuna (Thunnus albacares) during their reproductive cycle was investigated using a combination of different trophic tracers, i.e., stomach contents and dual stable isotope analysis, along with an assessment of ovarian development based on a histological analysis. To complete these analyses, we collected 215 f...

The inaugural CLIOTOP meeting in Sete, France, in 2003 established 5 working groups, one of which was Working Group 3 (Trophodynamics of Ocean Top Predators). The problem that I and my co-chairs, Robert Olson and Frederic Menard, faced was that most “feeding studies” were regionally based. Broader comparisons within and between oceans relied mainly...

Recent observations of unusual mass stranding and mortality of two Indian Ocean crustacean species, the swimming crab Charybdis smithii and the mantis shrimp Natosquilla investigatoris , are documented and analysed. Strandings of C. smithii were observed for the first time in the equatorial Indian Ocean, the main area of its pelagic distribution. S...

Endogenous and environmental variables are fundamental in explaining variations in fish condition. Based on more than 20 yr of fish weight and length data, relative condition indices were computed for anchovy and sardine caught in the Gulf of Lions. Classification and regression trees (CART) were used to identify endogenous factors affecting fish c...

Three body condition indices were compared in three small pelagic fish species.•Bioenergetic index (fatmeter) correlated well with biochemical lipid estimation.•The morphometric index appears more integrative and reflects more than just lipids.•Fatmeter repeatability was high and frozen storage did not affect its measurements.•The fatmeter allows t...

Productivity and Susceptibility Analysis (PSA) is a methodology for evaluating the vulnerability of a stock based on its biological productivity and susceptibility to fishing. In this study, we evaluated the vulnerability of 60 stocks of tuna, billfishes and other teleosts caught by the tuna longline fleets operating in the South Atlantic and India...

Assessment of isotopic compositions at the base of food webs is a prerequisite for using stable isotope analysis to assess foraging locations and trophic positions of marine organisms. Our study represents a unique application of stable-isotope analyses across multiple trophic levels (primary producer, primary consumer and tertiary consumer) and ov...