Éditeur(s) : Inter-research
Résumé : Environmental conditions experienced by aquatic organisms are archived in biogenic carbonates such as fish otoliths, bivalve shells and coral skeletons. These calcified structures present an accretionary growth and variations in optical properties - color or opacity - that are used to reconstruct time. Full and reliable exploitation of the information extracted from these structures is, however, often limited as the metabolic processes that control their growth and their optical properties are poorly understood. Here, we propose a new modeling framework that couples both the growth of a biogenic carbonate and its optical properties with the metabolism of the organism. The model relies on well-tested properties of Dynamic Energy Budget (DEB) theory. It is applied to otoliths of the Bay of Biscay anchovy (Engraulis encrasicolus) for which a DEB model has been previously developed. The model reproduces well-known otolith patterns and thus provides us with mechanisms for the metabolic control of otolith size and opacity at the scale of an individual lifespan. Two original contributions using this framework are demonstrated. First, the model can be used to reconstruct the temporal variations in the food assimilated by an individual fish. Reconstructing food conditions of past and present aquatic species in their natural environment is key ecological information to better understand population dynamics. Second, we show that non-seasonal checks can be discriminated from seasonal checks, which is a well-recognized problem when interpreting fish otoliths. We discuss further developments of the model and the experimental settings required to test this new promising framework.
Marine Ecology-progress Series (0171-8630) (Inter-research), 2012 , Vol. 447 , P. 151-164

Droits : 2012 Inter-Research
http://archimer.ifremer.fr/doc/00060/17082/14593.pdf
DOI:10.3354/meps09492
http://archimer.ifremer.fr/doc/00060/17082/

Éditeur(s) : Elsevier
Résumé : A study was conducted using a bioenergetics approach to generate information on energy requirement and feed utilization of Litopenaeus stylirostris. Animals (initial mean weight 21 +/- 1 g were fed ad libitum six experimental diets, ranging from 25 to 58% crude protein (CP), for 50 days. Weight gain increased from 21 to 30 g with increasing dietary protein level. Survival rates averaged 80%. Basal metabolism (HeE) and heat increment of feeding (HiE) were monitored using respirometry. HeE was on average I U shrimp(-1) day(-1) or 47 U kg live weight(-1) day (22 kJ/kg(0.8). d(-1)), slightly more than what is observed in fish. HiE averaged 0.2 W/sbrimp(-1) day(-1) or 10 W kg live weight(-1) day(-1) (4 kJ/kg(0.8) d(-1)). It represented 3 1 % and 12% digestible energy intake (DET) for shrimp fed on 58% CP and 25% CP diet respectively. Non-fecal (UE + ZE) energy calculated on the basis of N-ammonia excretion averaged 0.2 jig N-ammonia/g dry wt./ mn or 25 J live shrimp(-1) day(-1) in fasting stage and increased to 40 J in post-prandial stage. Ammonia production increased with increasing dietary crude protein (CP). The O:N ratio indicated that protein was increasingly used as an energy substrate as CP increased. The information was used to construct an energy budget for shrimp fed a protypical 40% CP diet. Gross energy intake (IE) was estimated at 6.5 W live shrimp(-1) day(-1); digestible energy intake (DEI) at 5, urinary and branchial excretion (UE +ZE) at 1.2, total heat production (HE) at 3.2; recovered energy (RE) at 0.6 (or 11% DEI). L. stylirostris adults issued from domesticated strain appeared to be more efficiently utilizing (i.e. converting into carcass energy) protein than carbohydrates. This preliminary energy budget can be used to construct theoretical feed requirement and waste outputs model for L. stylirostris. (C) 2007 Published by Elsevier B.V.
Aquaculture (0044-8486) (Elsevier), 2007-10 , Vol. 271 , N. 1-4 , P. 439-448

Droits : 2007 Published by Elsevier B.V.
http://archimer.ifremer.fr/doc/2007/publication-6263.pdf
DOI:10.1016/j.aquaculture.2006.05.062
http://archimer.ifremer.fr/doc/00000/6263/

Éditeur(s) : Montpellier 1
Résumé : Understanding bioaccumulation mechanisms of persistent organic pollutants (POPs) is a major issue for environmental risk assessment. In this work, polychlorinated biphenyls (PCBs), a model contaminant family, has been studied in the European hake (Merluccius merluccius), a high trophic level species from the Gulf of Lions. High concentrations of PCBs were measured in hake from this area compared to those encountered in the population of the Bay of Biscay. PCB biomagnification was highlighted along its food web from marine phytoplankton, suggesting a strong influence of diet on contamination levels. The role of other biological processes was also apprehended in order to understand the high variability of observed levels. Thus, growth, sex, and also the degree of sexual maturity appear as major factors explaining the measured concentrations in fish. A PCB bioaccumulation model in the hake, based on the Dynamic Energy Budget theory (DEB), was developed. This approach is based on a bioenergetic model, reproducing the main physiological functions of an organism (feeding, growth and reproduction), coupled with a kinetic model of contaminants. The growth and evolution of contamination levels of several PCB congeners during the life of male and female hakes is satisfactorily simulated, both in the Gulf of Lions and in the Bay of Biscay, validating the processes taken into account. This combined modelling approach appears well adapted to study the fate of contaminants in fish, and paves the way for a realistic understanding of their effects on major biological functions of fish.
La compréhension des mécanismes de bioaccumulation des contaminants organiques persistants (POP) est un enjeu majeur pour l'évaluation des risques environnementaux. Lors de ce travail, le devenir d'une famille de contaminants modèles, les polychlorobiphényles (PCB), a été étudié chez une espèce de rang trophique élevé du golfe du Lion, le merlu Européen (Merluccius merluccius). Des concentrations élevées en PCB ont été mesurées dans les merlus de ce secteur en comparaison à celles rencontrées dans la population du golfe de Gascogne. La mise en évidence d'une bioamplification des PCB le long de son réseau trophique, depuis le phytoplancton marin, suggère une influence importante de l'alimentation sur les niveaux de contamination. Le rôle d'autres processus biologiques a également été appréhendé afin de comprendre la forte variabilité des niveaux observés. Ainsi, la croissance, le sexe, mais également le degré de maturité sexuel apparaissent comme des facteurs explicatifs majeurs des concentrations en PCB mesurées dans les poissons. Un modèle de bioaccumulation des PCB chez le merlu, basé sur la théorie de Budget d'Energie Dynamique (DEB), a été développé. Il s'agit d'une approche basée sur le couplage d'un modèle bioénergétique, reproduisant les principales fonctions physiologiques de l'organisme (nutrition, croissance et reproduction), avec un modèle de cinétique des contaminants. La croissance et l'évolution des niveaux de contamination de plusieurs congénères de PCB au cours de la vie des merlus mâles et femelles est simulée de manière satisfaisante, tant dans le golfe de Gascogne que dans le golfe du Lion, validant ainsi les processus pris en compte. Cette approche combinée de modélisation apparaît tout à fait adaptée à l'étude du devenir des contaminants chez les poissons, et ouvre la voie à une compréhension réaliste de leurs effets sur les grandes fonctions biologiques de ces organismes.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2008/these-6490.pdf
http://archimer.ifremer.fr/doc/00000/6490/

Éditeur(s) : HAL CCSD Oldendorf/Luhe
Résumé : International audience
Non-calcifying photosynthetic anthozoans have emerged as a group that may thrive under high carbon dioxide partial pressure (pCO(2)) conditions via increased productivity. However, the physiological mechanisms underlying this potential success are unclear. Here we investigated the impact of high pCO(2) on the dissolved inorganic carbon (DIC) use in the temperate sea anemone Anemonia viridis. We assessed the impacts of long-term exposure to high pCO(2), i.e. sampling in situ natural CO2 vents (Vulcano, Italy), and short-term exposure, i.e. during a 3 wk controlled laboratory experiment. We focused on photo-physiological parameters (net photosynthesis rates, chlorophyll a content and Symbiodinium density) and on carbonic anhydrase (CA) activity, an enzyme involved in the energy-demanding process of DIC absorption. Long-term exposure to high pCO(2) had no impact on Symbiodinium density and chlorophyll a content. In contrst, short-term exposure to high pCO(2) induced a significant reduction in Symbiodinium density, which together with unchanged net photosynthesis resulted in the increase of Symbiodinium productivity per cell. Finally, in both in situ long-term and laboratory short-term exposure to high pCO(2), we observed a significant decrease in the CA activity of sea anemones, suggesting a change in DIC use (i.e. from an HCO3- to a CO2 user). This change could enable a shift in the energy budget that may increase the ability of non-calcifying photosynthetic anthozoans to cope with ocean acidification.
ISSN: 0171-8630

hal-01546163
https://hal.archives-ouvertes.fr/hal-01546163
DOI : 10.3354/meps11916

Éditeur(s) : Gauthier-Villars
Résumé : Five particle traps were deployed at depths of 4 400 to 4 900 rn at two stations on the Demerara abyssal plain and one station on the Cape Verde abyssal plain (tropical Atlantic). At the same time, an intensive sampling of superficial sediments was carried out using a 0,25 m2 box corer. The total particle flux varied from 372 to 87,7 mg dry weightfm2/day. The average concentration of organic carbon was 40 mg/g of material collected. ln the surface sediment this was only 4 mg/g. A direct relationship existed between the intensity of the flux of organic matter and the richness of the organic matter of the deposited sediment. According to our calculations, more than 90% of the organic matter arriving at the bottom is consumed by the abyssal benthos and only 1% is lost to permanent sediment deposits. For 100 calories consumed by the benthos, 99 are utilized by the infauna and flora, 0, 7 by the holothurian egafauna and 0,3 by near-bottom fisches. The biochemical composition of the particles is characterized at ali stations by a predominance of "humic" material in the total organic matter (more than 55%). The part of the molecules unaltered form living material varied from on station to another: for the most oceanic station the protein dominated, composing 20% of the total energy. At the station onder the influence of the continent the lipid fraction grew and was almost equal to that of the protein. ln this case, the carbohydrate fraction was very weak (7% of the organic matter). Finally the preference of the animais which feed on the particles is principally for the most energetic (lipid) and the most easily hydrolysable (labile protein) molecules: the other molecules, such as the humic matter, are less preferred, although they still contribute to about half of the energy consumed by the abyssal benthic animais.
Cinq pièges à particules ont été déployés à des profondeurs comprises entre 4400 et 4 900 rn sur deux stations dans la plaine abyssale de Demerara et une station dans la plaine abyssale du Cap Vert (Atlantique tropical). Dans le même temps, un échantillonnage intensif du sédiment superficiel a été réalisé à l'aide d'un carottier de 0,25 m2 d'ouverture. Le flux particulaire total mesuré varie de 372 mg de matière sèche/m2/jour à 87,7 mg/m2/g de matériel récolté. Dans les sédiments superficiels, elle n'est plus que d'environ 4 mg/g. Il existe une relation directe entre l'intensité du flux organique et la richesse en composés organiques du sédiment. D'après nos estimations, plus de 90% du matériel organique arrivant sur le fond sont consommés par les organismes benthiques abyssaux et seulement 1% est perdu dans la sédimentation permanente. Pour 100 calories consommées par le benthos, 99 le sont par la petite faune et la flore vivant dans le sédiment, 0, 7 calories sont utilisées par les holothuries (mégafaune) et 0,3 calories par les poissons. La composition biochimique des particules se caractérise, à toutes les stations, par la prédominance des composés organiques transformées néobiogéniques ( « humus ») dans la matière organique totale (plus de 55%). La part des molécules de la matière vivante varie d'une station à l'autre: à la station la plus océanique, les protéines dominent et composent 200/o de l'énergie totale des apports. Dans la station plus soumise aux influences continentales, la concentration en lipides augmente et peut égaler celle des protéines. Dans ce cas, le taux de glucides des particules est très faible (7% des apports organiques). Enfin, les préférences nutritionnelles des animaux qui s'alimentent sur ces particules se portent principalement sur les molécules les plus énergétiques (lipides) et les plus facilement hydrolysables (protéines labiles) : les autres molécules, comme les composés néobiogéniques sont moins recherchés bien qu'ils contribuent pour moitié à l'énergie consommée par les animaux benthiques abyssaux
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1985 , Vol. 8 , N. 3 , P. 293-301

Droits : Gauthier-Villars
http://archimer.ifremer.fr/doc/00112/22318/19991.pdf
http://archimer.ifremer.fr/doc/00112/22318/

Éditeur(s) : Elsevier
Résumé : Bioaccumulation is difficult to document because responses differ among chemical compounds, with environmental conditions, and physiological processes characteristic of each species. We use a mechanistic model, based on the Dynamic Energy Budget (DEB) theory, to take into account this complexity and study factors impacting accumulation of organic pollutants in fish through ontogeny. The bioaccumulation model proposed is a comprehensive approach that relates evolution of hake PCB contamination to physiological information about the fish, such as diet, metabolism, reserve and reproduction status. The species studied is the European hake (Merluccius merluccius, L. 1758). The model is applied to study the total concentration and the lipid normalised concentration of 4 PCB congeners in male and female hakes from the Gulf of Lions (NW Mediterranean sea) and the Bay of Biscay (NE Atlantic ocean). Outputs of the model compare consistently to measurements over the life span of fish. Simulation results clearly demonstrate the relative effects of food contamination, growth and reproduction on the PCB bioaccumulation in hake. The same species living in different habitats and exposed to different PCB prey concentrations exhibit marked difference in the body accumulation of PCBs. At the adult stage, female hakes have a lower PCB concentration compared to males for a given length. We successfully simulated these sex-specific PCB concentrations by considering two mechanisms: a higher energy allocation to growth for females and a transfer of PCBs from the female to its eggs when allocating lipids from reserve to eggs. Finally, by its mechanistic description of physiological processes, the model is relevant for other species and sets the stage for a mechanistic understanding of toxicity and ecological effects of organic contaminants in marine organisms.
Journal of Sea Research (1385-1101) (Elsevier), 2009-10 , Vol. 62 , N. 2-3 , P. 124-134

Droits : 2009 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/2009/publication-6789.pdf
DOI:10.1016/j.seares.2009.02.006
http://archimer.ifremer.fr/doc/00000/6789/

Éditeur(s) : Elsevier Science Bv
Résumé : There has been growing interest in the development of mud crab aquaculture in New Caledonia. However, for this to become established at a commercial level, a cost-effective formulated feed based on internationally-available ingredients needs to be developed. We have evaluated the optimal dietary protein content for juvenile crabs, Scylla serrata (Forskål, 1775), using a series of diets with a protein content ranging from 27 to 49% and soy protein concentrate (SPC) as the main protein source. For this purpose, 54 individually housed crabs were allocated to five dietary treatments (n = 10 or 11). The crabs were fed ad libitum, for 81 days with the allocated diets. The apparent digestibilities of dry mater, crude protein and energy were high (96.2-97.3%), irrespective of the diet. The voluntary feed intake (VFI) of crabs widely varied from 46 to 220 g kg- 1of fresh initial body weight per week (iBW week- 1) whatever the diet. However, SPC intake and protein intake increased significantly with dietary protein content up to the diet with 40% crude protein, but did not increase further with diets containing 44% and 49% crude protein. The cumulative molts were strongly affected by the VFI levels or energy intake and also, to a lesser extent, by the levels of SPC or protein in diets. Two phases in tissue gain were observed after ecdysis: an initial deposition phase lasting around 30 days followed by a plateau which lasted until the next molt. The daily tissue growth was 16.5% of dry body weight (dry BW) one day after ecdysis and dramatically decreased to 3.6% of dry BW over the first 10 days, then decreased more slowly to the minimum value of 1.3% of dry BW over the next 70 days. During the course of experiment, the best growth (tissue growth and molt frequency) and the best feed efficiency (FCR, PER, retention of proteins and lipids) were obtained with crabs fed on the diet with 40% crude protein. This result was confirmed by a bioenergetic study which showed significantly higher allocation of the energy intake for growth (RE) of crabs fed on diet 40% crude protein. Finally, under our experimental conditions, 1 kg of juvenile crabs required 6.5 ± 1.1 g of protein per day. This level was obtained with the diet SPC-42 that contained 40% of protein of which almost three quarters were derived from SPC. Two hypotheses are proposed to explain the negative effect of high level of SPC or protein on growth and feed efficiency for crabs fed on in diets containing 52% and 60% SPC.
Aquaculture (0044-8486) (Elsevier Science Bv), 2014-10 , Vol. 434 , P. 499-509

Droits : 2014 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00211/32196/30630.pdf
http://archimer.ifremer.fr/doc/00211/32196/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Transport of liquid and gaseous hydrocarbons through focused fluid flow systems is a widespread process in continental margins and sedimentary basins, which is gaining increased attention in the assessment of geohazards, environment conservation, and securing fossil energy resources. Studying the abundance, distribution and drivers for this process is crucial for understanding its role in 1) the dynamics of gas hydrate accumulation and destabilization, 2) submarine slope stability and related tsunamis, 3) the plethora of chemosynthetic benthic ecosystems that develop in deep seep sites, and 4) the input of greenhouse gases (e.g. methane) into the ocean/atmosphere system, which may influence the atmospheric carbon budget and Earth's paleo- and present climate. New ocean exploration tools provide ever more data and improve our understanding of these systems. However, the subject still suffers from a lack of interdisciplinary knowledge dissemination. The ongoing international debate about the timing and the processes that control fluid expulsion in sedimentary basins is fuelled by their implications for structural and petroleum geology. Because fluids expelled at cold seeps originate at depth they represent open windows into the underlying petroleum systems and are valuable indicators for the reservoir systems. They may also help in deciphering past and predicting future climate change because worldwide release of large amounts of fluids may have an impact on the chemistry of the ocean and atmosphere.
ISSN: 0025-3227

hal-00772472
https://hal.archives-ouvertes.fr/hal-00772472
DOI : 10.1016/j.margeo.2012.10.012

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
This study investigates if acclimatization to residual pesticide contamination in agricultural soils is reflected in detoxification, antioxidant enzyme activities and energy budget of earthworms. Five fields within a joint agricultural area exhibited different chemical and farming histories from conventional cultivation to organic pasture. Soil multiresidual pesticide analysis revealed up to 9 molecules including atrazine up to 2.4 ng g(-1) dry soil. Exposure history of endogeic Aporrectodea caliginosa and Allolobophora chlorotica modified their responses to pesticides. In the field, activities of soluble glutathione-S-transferases (sGST) and catalase increased with soil pesticide contamination in A. caliginosa. Pesticide stress was reflected in depletion of energy reserves in A. chlorotica. Acute exposure of pre-adapted and naïve A. caliginosa to pesticides (fungicide Opus(®), 0.1 μg active ingredient epoxiconazole g(-1) dry soil, RoundUp Flash(®), 2.5 μg active ingredient glyphosate g(-1) dry soil, and their mixture), revealed that environmental pre-exposure accelerated activation of the detoxification enzyme sGST towards epoxiconazole.
ISSN: 0269-7491

hal-01063923
https://hal.archives-ouvertes.fr/hal-01063923
DOI : 10.1016/j.envpol.2014.05.001
PUBMED : 24874794

Éditeur(s) : Public Library Science
Résumé : The blue mussel, Mytilus edulis, is a commercially important species, with production based on both fisheries and aquaculture. Dynamic Energy Budget (DEB) models have been extensively applied to study its energetics but such applications require a deep understanding of its nutrition, from filtration to assimilation. Being filter feeders, mussels show multiple responses to temporal fluctuations in their food and environment, raising questions that can be investigated by modeling. To provide a better insight into mussel–environment interactions, an experiment was conducted in one of the main French growing zones (Utah Beach, Normandy). Mussel growth was monitored monthly for 18 months, with a large number of environmental descriptors measured in parallel. Food proxies such as chlorophyll a, particulate organic carbon and phytoplankton were also sampled, in addition to non-nutritious particles. High-frequency physical data recording (e.g., water temperature, immersion duration) completed the habitat description. Measures revealed an increase in dry flesh mass during the first year, followed by a high mass loss, which could not be completely explained by the DEB model using raw external signals. We propose two methods that reconstruct food from shell length and dry flesh mass variations. The former depends on the inversion of the growth equation while the latter is based on iterative simulations. Assemblages of food proxies are then related to reconstructed food input, with a special focus on plankton species. A characteristic contribution is attributed to these sources to estimate nutritional values for mussels. M. edulis shows no preference between most plankton life history traits. Selection is based on the size of the ingested particles, which is modified by the volume and social behavior of plankton species. This finding reveals the importance of diet diversity and both passive and active selections, and confirms the need to adjust DEB models to different populations and sites.
Plos One (1932-6203) (Public Library Science), 2014-10 , Vol. 9 , N. 10 , P. 1-13

Droits : 2014 Picoche et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
http://archimer.ifremer.fr/doc/00218/32895/31380.pdf
http://archimer.ifremer.fr/doc/00218/32895/31381.pdf
http://archimer.ifremer.fr/doc/00218/32895/31382.pdf
http://archimer.ifremer.fr/doc/00218/32895/31383.pdf
http://archimer.ifremer.fr/doc/00218/32895/31384.pdf