Sébastien Lefebvre

Université de Lille · Marine Station Wimereux

Knowledge of the trophic structure and variability of planktonic communities is a key factor in understanding food-web dynamics and energy transfer from zooplankton to higher trophic levels. In this study, we investigated how stable isotopes of mesozooplankton species varied seasonally (winter, spring, autumn) in relation to environmental factors a...

The mechanistic approach consisting of coupling Dynamic Energy Budget (DEB) models to Individual-Based Models (IBMs) allows simulating individual and population biological traits and their dynamics. This approach was developed here to study population dynamics of two sympatric intertidal ecosystem engineers, Arenicola marina and Arenicola defodiens...

Thus far, no long-term in situ observation of planktonic biomass have been undertaken to optimize the black-lip pearl oyster aquaculture in the remote Tuamotu atolls. The feasibility of using data from the OLI sensor onboard Landsat-8 satellite to determine chlorophyll a concentrations (Chla) in a deep atoll, Ahe, was then assessed over the 2013–20...

Arenicola marina, a marine benthic polychaete, is widespread on sandy beaches in Europe and considered as an ecosystem engineer despite commonly used as bait by fishermen. Data regarding the bioenergetics of the lugworm larval stages are still incomplete. Trochophore is initially lecithotroph and then becomes planktotroph while growing as metatroch...

This editorial presents results of the MANA (MANagement of Atolls) project compiled in the form of a Marine Pollution Bulletin collection of 14 articles. MANA is a project funded by the French Agence National pour la Recherche that specifically addresses the development of knowledge and management tools for pearl farming atolls, with a focus on the...

Stable isotope ratios are used to reconstruct animal diet in trophic ecology via mixing models. Several assumptions of stable isotope mixing models are critical, i.e., constant trophic discrimination factor and isotopic equilibrium between the consumer and its diet. The isotopic turnover rate (λ and its counterpart the half-life) affects the dynami...

For species in the deep sea, there is a knowledge gap related to their functional traits at all stages of their life cycles. Dynamic energy budget (DEB) theory has been proven to be an efficient framework for estimating functional traits throughout a life cycle using simulation modelling. An abj-DEB model, which compared with the standard DEB model...

The ability to efficiently implement ecosystem-based fisheries management is largely dependent on data availability. As invertebrates are not included in routine monitoring programmes, data should be collected by different approaches. We assessed whether fish could be suitable biological samplers of benthic invertebrates in the Eastern English Chan...

Studying how natural phytoplankton adjust their photosynthetic properties to the quantity and quality of underwater light (i.e. light climate) is essential to understand primary production. A wavelength-dependent photoacclimation strategy was assessed using a multi-color pulse-amplitude-modulation chlorophyll fluorometer for phytoplankton samples c...

This study addresses the temporal variability of couplings between pelagic and benthic habitats for fish assemblages at five periods in a shallow epicontinental sea, the Eastern English Channel (EEC). Organic matter fluxes fueling fish assemblages and the relative contribution of their different sources were assessed using stable isotope analysis a...

Two large but independent bodies of literature exist on two essential components of the dynamics of isotopic incorporation: the isotopic incorporation rate (λ) and the trophic discrimination factor (Δ). Understanding the magnitude of these two parameters and the factors that shape them is fundamental to interpret the results of ecological studies t...

From 2000 to 2016, substantial changes in biomass and community structure of small pelagic fish and mesozooplankton have been reported in the Bay of Biscay. Since significant relationships have been found between phytoplankton chlorophyll a and mesozooplankton as well as between phytoplankton chlorophyll a and shifts in sardine body condition, it w...

Integrated Multi-Trophic Aquaculture (IMTA) systems have been designed to optimize nutrient and energy use, to decrease waste, and to diversify fish-farm production. Recently, the development of detritivorous aquaculture has been encouraged, as detrivores can consume organic particulate matter, reducing benthic eutrophication and the environmental...

• Using stable isotope ratios to explore the trophic ecology of freshwater animals requires knowledge about effects of food quality on isotopic incorporation dynamics. The aim of this experimental study was to: (1) estimate carbon and nitrogen isotopic incorporation rates and trophic discrimination factors (TDFs) of a freshwater first‐feeding fish...

Carbon (δ 13 C) and nitrogen (δ 15 N) stable isotope analyses are used in marine ecology to study trophic relationships and migrations of species since they reflect dietary sources consumed which may vary geographically. However, better estimations of isotope incorporation rates and trophic discrimination factors (TDF) under controlled conditions a...

Arenicola marina (Annelida Polychaeta) is a harvested ecosystem engineer inhabiting galleries within soft-sediment foreshores from the Mediterranean to the Arctic. It displays a typical distribution pattern on most foreshores, with the juveniles inhabiting the mediolittoral shore and migrating to the infralittoral shore while growing. In this study...

The black-lipped pearl oyster (Pinctada margaritifera) is extensively farmed in French Polynesia to produce black pearls. For a sustainable management of marine resources, studying interactions between organisms and environment, and the associated factors and processes that will impact their life cycle and thus modulate population dynamics is a maj...

This study aims at (1) experimentally estimating first sexual maturation of the European sardine S. pilchardus, (2) using the results to calibrate existing bioenergetic models. During the 183 days-experiment, fish growth and body condition were assessed by biometry, and gonads were weighed when present. Age, total length and wet weight at first mat...

Internation conference at the 68th Annual meeting of the British Phycological Society

Considering the ecological importance and potential value of Hediste diversicolor , a better understanding of its metabolic rate and potential growth rates is required. The aims of this study are: (i) to describe key biometric relationships; (ii) to test the effects of temperature and body size on standard metabolic rate (as measure by oxygen consu...

Trophic ecology is the study of feeding interactions and food acquisition by organisms. It includes the causes and consequences of those behaviours at all levels of biological organisation. As a field of research, it crosses many disciplinary boundaries and provides knowledge that is pertinent to many other areas of ecology. Here we list and catego...

Arenicola spp. are marine benthic polychaetes dug for bait by anglers. Without regulation, this activity can lead to the decrease of lugworms' population meanwhile affecting the physical characteristics of the beach and the biodiversity. Here, we identified through morphology and genetics two species of lugworms, Arenicola marina and A. defodiens,...

an output for the GDR "trophic Ecology"

The link between harmful algal blooms, phytoplankton community dynamics and global environmental change is not well understood. To tackle this challenging question, a new method was used to reveal how phytoplankton communities responded to environmental change with the occurrence of an harmful algae, using the coastal waters of the eastern English...

A model was developed to reproduce temporal variation of microphytobenthos (MPB), bacteria, and nutrients in the first centimeter of sediment. Physiological processes of MPB such as vertical migration and EPS (Extracellular Polymeric substance) production were integrated in the model. Endogenous process represented by the C:N ratio of MPB was set a...

Whether considered as a risk for human health or as ecological tracers, contaminants' concentrations measured in fish muscles are commonly expressed relative to wet or dry mass. Comparison of results required conversion factors (CF) but accurate values are scarce and case-specific. The present paper is aimed at investigating errors linked with the us...

This study is the first in situ work comparing Rapid Light Curves (RLC) and Non Sequential Steady-State Light Curves (N-SSLC) in their efficiency to characterize phytoplankton photosynthetic activity and acclimation status. Measurements were carried out at two time scales (daily and annual) using the Pulse Amplitude Modulated fluorometry on samples...

The ecological niche concept has regained interest under environmental change (e.g., climate change, eutrophication, and habitat destruction), especially to study the impacts on niche shift and conservatism. Here, we propose the within outlying mean indexes (WitOMI), which refine the outlying mean index (OMI) analysis by using its properties in com...

WitOMI results and specie’s code. Tables S1 and S2 are the results of the OMI analysis, the value of the WitOMI parameters and their respective P values, for species of both ecological examples. Tables S3 and S4 are the respective code for each species of both ecological examples.

Within Outlying Mean Indexes Calculations. Mathematical description of the WitOMI parameters.

Depth is one of the environmental variables influencing the structure of marine food webs by directly or indirectly influencing benthic-pelagic coupling and predator-prey relationships. In shallow waters, the high degree of connectivity between pelagic and benthic networks results in complex systems with multiple interactions. Digestive tract (DT)...

• Isotopic analyses are increasingly used to assess the structure of food webs and a series of isotopic functional indices have been proposed in the last decade to characterize this structure. These indices are based on the foundational assumption that proximity in the isotopic space informs on trophic similarity between species. While it has been...

The ecological niche concept has a revival interest under climate change, especially to study its impact on niche shift and/or conservatism. Here, we propose the Within Outlying Mean Indexes (WitOMI), which refines the Outlying Mean Index (OMI) analysis by using its properties in combination with the K-select analysis species marginality decomposit...

The ecological niche concept has a revival interest under climate change, especially to study its impact on niche shift and/or conservatism. Here, we propose the Within Outlying Mean Indexes (WitOMI), which refines the Outlying Mean Index (OMI) analysis by using its properties in combination with the K-select analysis species marginality decomposit...

We studied the influence of food availability on the growth (whole body and organs) of the oyster Crassostrea gigas and on the dynamics of their delta C-13 and delta N-15 respective values. Juvenile oysters originating from Arcachon Bay were transplanted to two contrasting ecosystems, Baie des Veys (BDV) and Rade de Brest (RDB), for a 1-yr growth s...

Trophic enrichment factors (TEF) are essential to properly and fruitfully explore stable isotope analysis in ecology. And so is the time window of food sources integration, usually estimated with the turnover rates (λ) of isotopic incorporation. On the road to provide ecologists with a general and reliable method to obtain TEF and turnover rates fo...

We studied the influence of food availability on the growth (whole body and organs) of the oyster Crassostrea gigas and on the dynamics of their δ¹³C and δ¹⁵N respective values. Juvenile oysters originating from Arcachon Bay were transplanted to two contrasting ecosystems, Baie des Veys (BDV) and Rade de Brest (RDB), for a 1 -yr growth survey. In B...

Individual diet variation (i.e. diet variation among individuals) impacts intra-and inter-specific interactions. Investigating its sources and relationship with species trophic niche organization is important for understanding community structure and dynamics. Individual diet variation may increase with intra-specific phenotypic (or " individual st...

Few studies have documented large-scale variations of trophic relationships along environmental gradients, especially in marine ecosystems, despite this topic being recognized as critical for food-web functioning understanding. Recent theoretical work demonstrated the importance of bentho-pelagic coupling in shaping the structure and functioning of...

Project LIMICO Ghent-Lille Kick off

Trophic networks are complex systems, with interactions at different levels that controls ecosystem functioning. They are also under the control of abiotic parameters, such as depth, that drive organic matter fluxes. Thus, it can be useful to combine contaminants with classic trophic markers (such as C and N stable isotopes) to track organic matter...

δ13C and δ15N values of two generalists primary consumers, a strict deposit-feeder polychaete (Arenicola marina), and a strict suspension-feeder bivalve (Crassostrea gigas), were investigated to typify the trophic functioning of two contrasted marine coastal ecosystems (eutrophic and mesotrophic, east and west Cotentin peninsula respectively, Engli...

Abstract Intertidal zones are dynamic areas, where tidal currents and wind-induced waves are responsible of resuspension of the sediment and associated microphytobenthos (MPB). Sediment composition (mud–sand mixtures) and MPB biofilm age are two major components involved in resuspension of epipelic microphytobenthos in muddy areas. However, their r...

Seminar UMR Marbec Montpellier, 13th of may 2015

Seminar University of Palermo, Sicily, 4th of may 2015

The temporal variability in phytoplankton photosynthetic activity was studied in the coastal waters of the Strait of Dover and related to environmental conditions. Phytoplankton photosynthetic activity data collected from October 2008 and August 2010 at different time scales (hourly to interannual) using a nested sampling design are presented. Phot...

Carbon and nitrogen stable isotopes are increasingly used to study the trophic relationships in marine ecosystems. The pilchard Sardina pilchardus is a key species among small pelagic fish in the functioning of marine pelagic food webs in the Northeastern Atlantic Ocean. Pilchards were caught in 2014 in the Bay of Biscay and were maintained during...

In response to the closure of shellfish production sites due to increasing occurrence of toxic algal blooms, land-based recirculating aquaculture systems (RAS) could be used by producers to store a proportion of their stock temporarily. An RAS prototype was tested in this study to store Pacific oyster Crassostrea gigas over a range of temperatures....

Relationships between bacteria, microphytobenthos and extracellular polymeric substances (EPS) that make up microbial biofilms over bare mudflats were investigated at an hourly frequency during two 14-day spring-neap cycles in winter and summer 2008. Bacterial abundance and total chl a concentration were lower in summer (0.78×108±SD 0.39×108cell.m-...

The quantification of overall microphytobenthos productivity should include the export of biomass from the intertidal zone during high tides, which implies refined estimates and concepts of erosion parameters. For the first time, the export of microphytobenthic cells was assessed over an intertidal mudflat in the Marennes-Oléron bay, France, during...

The migratory shorebirds of the East Atlantic flyway land in huge numbers during a migratory stopover or wintering on the French Atlantic coast. The Brouage bare mudflat (Marennes-Oléron Bay, NE Atlantic) is one of the major stopover sites in France. The particular structure and function of a food web affects the efficiency of carbon transfer. The...

The migratory shorebirds of the East Atlantic flyway land in huge numbers during a migratory stopover or wintering on the French Atlantic coast. The Brouage bare mudflat (Marennes-Oléron Bay, NE Atlantic) is one of the major stopover sites in France. The particular structure and function of a food web affects the efficiency of carbon transfer. The...

The migratory shorebirds of the East Atlantic flyway land in huge numbers during a migratory stopover or wintering on the French Atlantic coast. The Brouage bare mudflat (Marennes-Oléron Bay, NE Atlantic) is one of the major stopover sites in France. The particular structure and function of a food web affects the efficiency of carbon transfer. The...

Photosynthetic parameters, phytoplankton assemblages and physicochemical parameters were analysed in the Strait of Dover along an inshore-offshore transect between September 2008 and December 2009. The samples were collected weekly at 9 stations only at the surface or at both surface and depth. The photosynthetic activity was obtained by measuring...

Short-term changes in phytoplankton photosynthetic activity were studied during different periods of the years 2009 and 2010 in the coastal waters of a macrotidal ecosystem (the Strait of Dover, eastern English Channel). During each sampling period, samples were taken every 1.45 h., from sunrise to sunset, during at least 5 days distributed along a...

The extent of salmon farming’s influence on the environment and the uptake of particulate and dissolved effluents by benthic organisms was assessed using community structure and stable isotope analyses. Sediment cores were collected along two directions: perpendicular to and in the direction of the main residual current, at 0, 25 and 200 m from two...

Previous studies have demonstrated that ionic and non-ionic natural rubber-based coatings inhibit adhesion and growth of marine bacteria, fungi, microalgae, and spores of macroalgae. Nevertheless, the mechanism of action of these coatings on the different micro-organisms is not known. In the current study, antifouling activity of a series of these...

In aquaculture, particularly in bivalve hatcheries, the biochemical composition of algal diets has a strong influence on larval and post-larval development. Biochemical composition is known to be related to culture conditions, among which light represents a major source of variation. The effects of blue light on biochemical composition and photosyn...

A major challenge in ocean and coastal management is to find simple ways to evaluate the health of such complex ecosystems. This task may prove complicated as selection criteria needs to be established for choosing appropriate indicators and evaluation tools which do not mask or leave out inherent ecosystem properties and dynamics. Here, we review...

European sardine (Sardina pilchardus) and European anchovy (Engraulis encrasicolus) are two species of economical and ecological significance in the Bay of Biscay (north-east Atlantic). However, the trophic ecology of both species is still poorly known in the area, and more generally, few studies have considered the potential trophic overlap betwee...

The high degree of physical factors in intertidal estuarine ecosystem increases material processing between benthic and pelagic compartments. In these ecosystems, microphytobenthos resuspension is a major phenomenon since its contribution to higher trophic levels can be highly significant. Understanding the sediment and associated microphytobenthos...

Stable isotopes are widely used in trophic ecology. Modelling is being performed at several steps and for different purposes. This key note aims at reviewing how modelling in its broad sense helps trophic ecology using stable isotopes as tracers. Mixing models are exploited to reconstruct diets and several versions of such tools exist, the more rec...

The structure, dynamics and productivity of marine ecosystems depend mainly on their underlying food webs. Marine food web structure can be partly characterized by fish species' trophic level. Trophodynamics studies often highlight size-related ontogenetic shifts in the diet of marine fishes, implying an increase of the trophic level according to f...

Background/Question/Methods The migratory shorebirds of the East Atlantic flyway massively land for migratory stopover or wintering on the French Atlantic coast. The Brouage bare mudflat is one of the major stopover sites in France. The activity of Brouage mudflat at low tide is based on the development of a microalgal biofilm which feeds the ben...

Intertidal flats of the estuarine macro-intertidal Baie des Veys (France) were investigated to identify spatial features of sediment and microphytobenthos (MPB) in April 2003. Gradients occurred within the domain, and patches were identified close to vegetated areas or within the oyster-farming areas where calm physical conditions and biodeposition...

Hydrological and photosynthetic parameters were investigated monthly from November 2009 to December 2010 using an opportunity ship, along a transect in the central part of the English Channel. A powerful statistical method, a Partial Triadic Analysis (PTA), was applied on the physicochemical data set and highlighted the functioning of four differen...

La remise en suspension du microphytobenthos est contrôlée par un certain nombre de facteurs physiques tels que l'hydrodynamisme et biologiques comme la bioturbation. Afin de mieux caractériser ce phénomène, un écosystème estuarien a été étudié, à marée basse pour la zone intertidale et au jusant pour la colonne d'eau. Les premiers résultats suggèr...

Nous avons utilisé un modèle basé sur la théorie des Budgets d'Energie Dynamiques, paramétré pour l'espèce Crassostrea gigas et calibré sur des données de la littérature, afin de quantifier l'impact de la quantité de nourriture f sur le fractionnement isotopique Δ. Une augmentation d'un facteur 5 de f entraîne une diminution de 35 % et 43 % du Δ13C...

We studied the dynamics of stable isotopes δ 13 C and δ 15 N of an opportunistic suspension feeder the Pacific oyster (Crassostrea gigas) to better understand the factors that influence the trophic enrichment (trophic-shift, Δ) between primary producers and consumers. Most of the previous studies on this topic do not quantify mass fluxes or isotopi...

This study is the first field work that examines the use of rapid light curves (RLCs) for in situ assessment of microphytobenthos (MPB) photosynthetic activity. The advantages offered by RLC methodology respond primarily to in situ constraints concerning MPB ecology and behaviour. In particular, the rapidity of RLCs allows for a high number of repl...

Spatial patterns in ecological communities result from a combination of physical and biological factors. In an estuarine intertidal bay, spatial differences have been found in the structure of phytoplanktonic communities and in the biological performance of cultivated oysters. It has been hypothesised that trophic heterogeneity exists, although the...

Community assemblages of diatoms, green algae and cyanobacteria comprise the microphytobenthos (MPB), which inhabit benthic sediment ecosystems (Admiraal 1984; Underwood and Kromkamp 1999; Consalvey et al. 2004). Particular attention has been paid to the analysis of intertidal soft sediment systems, e.g. cohesive mudflat and sandy substrata typical...