Modelling paralytic shellfish toxins (PST) accumulation in Crassostrea gigas by using Dynamic Energy Budgets (DEB)

As other filter-feeders, Crassostrea gigas can concentrate paralytic shellfish toxins (PST) by consuming dinoflagellate phytoplankton species like Alexandrium minutum. Intake of PST in oyster tissues mainly results from feeding processes, i.e. clearance rate, pre-ingestive sorting and ingestion that are directly influenced by environmental conditions (trophic sources, temperature). This study aimed to develop a mechanistic model coupling the kinetics of PST accumulation and bioenergetics in C. gigas based on Dynamic Energy Budget (DEB) theory. For the first time, the Synthesizing Units (SU) concept was applied to formalize the feeding preference of oysters between non-toxic and toxic microalgae. Toxin intake and accumulation were both dependent on the physiological status of oysters. The accumulation was modelled through the dynamics of two toxin compartments: (1) a compartment of ingested but non-assimilated toxins, with labile toxins within the digestive gland eliminated via faeces production; (2) a compartment of assimilated toxins with a rapid detoxification rate (within a few days). Firstly, the DEB-PST model was calibrated using data from two laboratory experiments where oysters have been exposed to A. minutum. Secondly, it was validated using data from another laboratory experiment and from three field surveys carried out in the Bay of Brest (France) from 2012 to 2014. To account for the variability in PST content of A. minutum cells, the saxitoxin (STX) amount per energy units in a toxic algae (ρPST) was adjusted for each dataset. Additionally, the effects of PST on the oyster bioenergetics were calibrated during the first laboratory experiment. However, these effects were shown to depend on the strain of A. minutum. Results of this study could be of great importance for monitoring agencies and decision makers to identify risky conditions (e.g. production areas, seawater temperature), to properly assess detoxification step (e.g. duration, modalities) before any commercialization or to improve predictions regarding closing of shellfish areas

Is the meiofauna a good indicator for climate change and anthropogenic impacts?

Our planet is changing, and one of the most pressing challenges facing the scientific community revolves around understanding how ecological communities respond to global changes. From coastal to deep-sea ecosystems, ecologists are exploring new areas of research to find model organisms that help predict the future of life on our planet. Among the different categories of organisms, meiofauna offer several advantages for the study of marine benthic ecosystems. This paper reviews the advances in the study of meiofauna with regard to climate change and anthropogenic impacts. Four taxonomic groups are valuable for predicting global changes: foraminifers (especially calcareous forms), nematodes, copepods and ostracods. Environmental variables are fundamental in the interpretation of meiofaunal patterns and multistressor experiments are more informative than single stressor ones, revealing complex ecological and biological interactions. Global change has a general negative effect on meiofauna, with important consequences on benthic food webs. However, some meiofaunal species can be favoured by the extreme conditions induced by global change, as they can exhibit remarkable physiological adaptations. This review highlights the need to incorporate studies on taxonomy, genetics and function of meiofaunal taxa into global change impact research

Les microplastiques et leurs additifs dans les produits de la pêche : développements méthodologiques et prévalence

Increase in plastic production since the 1950's in combination with plastic waste mismanagement lead to the presence of plastic particle in terrestrial and marine environment. Plastic particles measuring less than 5 mm, called microplastics, are ingested by a wide range of organisms. The goal of this PhD thesis was to evaluate the microplastic hazard for seafood consumers. firstly, method for digesting seafood tissue without degrading plastic polymer was selected and applications limits were determined for digestion of fish digestive tracts. Concurrently, a Pyrolysis-GC/MS method was optimized, limit of detection were determined and this method was applied on environmental samples. Both methods were used to study microplastics contamination in bivalve and fish species used for human consumption. Bivalve contamination was between 0.15 and 0.74 MP/g of tissue wet weight whereas contaminations in fish were low. Indeed, digestive tracts were contaminated by in mean 0.01 MP/g of tissue wet weight and muscles were contaminated by in mean 0.001 MP/g of tissue wet weight. Lately, leaching of a plastic additive was studied using an in vitro enzymatic model of digestion. However, such phenomenon was not highlighted. Overall, these results will help to standardize the study of microplastics in seafood products.L'augmentation de la production de matière plastique depuis les années 1950 combinée à une mauvaise gestion des déchets plastiques ainsi qu'aux mauvais comportements des citoyens conduit à la contamination des écosystèmes terrestres comme marins. L'ingestion par des organismes marins de particules plastiques mesurant moins de 5 mm, appelées microplastiques, a été décrite. L'objectif de ces travaux de thèse était d'évaluer le danger "microplastique" pour le consommateur de produits de la pêche. Afin de répondre à cet objectif, la sélection et la caractérisation d'une méthode permettant de digérer les tissus des produits de la pêche a été. En parallèle, une méthode de Pyrolyse-GC/MS a été optimisée afin d'identifier les microplastiques les plus petits possibles. Ses limites d'applications ont été calculées puis la méthode a été appliquée sur des microplastiques provenant de différents produits de la pêche. Ces deux méthodes ont été appliquées dans la recherche de microplastiques dans deux espèces de bivalves et trois espèces de poissons. Pour les bivalves, la contamination aux microplastiques était comprise entre 0.15 et 0.74 MP/g de chair humide alors que pour les poissons la contamination était assez faible : 0,01 MP/g de tractus gastro-intestinal et 0,001 MP/g de filet. Pour finir, une étude exploratoire de la lixiviation d'un additif plastique en utilisant un modèle de digestion in vitro a été entreprise. Globalement, ces travaux de thèse permettent de proposer des voies d'harmonisation des méthodes pour l'étude des microplastiques dans les produits de la pêche pour, in fine, évaluer le danger pour le consommateur

Microplastics and their additives in seafood products : methodological developments and prevalence

L'augmentation de la production de matière plastique depuis les années 1950 combinée à une mauvaise gestion des déchets plastiques ainsi qu'aux mauvais comportements des citoyens conduit à la contamination des écosystèmes terrestres comme marins. L'ingestion par des organismes marins de particules plastiques mesurant moins de 5 mm, appelées microplastiques, a été décrite. L'objectif de ces travaux de thèse était d'évaluer le danger "microplastique" pour le consommateur de produits de la pêche. Afin de répondre à cet objectif, la sélection et la caractérisation d'une méthode permettant de digérer les tissus des produits de la pêche a été. En parallèle, une méthode de Pyrolyse-GC/MS a été optimisée afin d'identifier les microplastiques les plus petits possibles. Ses limites d'applications ont été calculées puis la méthode a été appliquée sur des microplastiques provenant de différents produits de la pêche. Ces deux méthodes ont été appliquées dans la recherche de microplastiques dans deux espèces de bivalves et trois espèces de poissons. Pour les bivalves, la contamination aux microplastiques était comprise entre 0.15 et 0.74 MP/g de chair humide alors que pour les poissons la contamination était assez faible : 0,01 MP/g de tractus gastro-intestinal et 0,001 MP/g de filet. Pour finir, une étude exploratoire de la lixiviation d'un additif plastique en utilisant un modèle de digestion in vitro a été entreprise. Globalement, ces travaux de thèse permettent de proposer des voies d'harmonisation des méthodes pour l'étude des microplastiques dans les produits de la pêche pour, in fine, évaluer le danger pour le consommateur.Increase in plastic production since the 1950's in combination with plastic waste mismanagement lead to the presence of plastic particle in terrestrial and marine environment. Plastic particles measuring less than 5 mm, called microplastics, are ingested by a wide range of organisms. The goal of this PhD thesis was to evaluate the microplastic hazard for seafood consumers. firstly, method for digesting seafood tissue without degrading plastic polymer was selected and applications limits were determined for digestion of fish digestive tracts. Concurrently, a Pyrolysis-GC/MS method was optimized, limit of detection were determined and this method was applied on environmental samples. Both methods were used to study microplastics contamination in bivalve and fish species used for human consumption. Bivalve contamination was between 0.15 and 0.74 MP/g of tissue wet weight whereas contaminations in fish were low. Indeed, digestive tracts were contaminated by in mean 0.01 MP/g of tissue wet weight and muscles were contaminated by in mean 0.001 MP/g of tissue wet weight. Lately, leaching of a plastic additive was studied using an in vitro enzymatic model of digestion. However, such phenomenon was not highlighted. Overall, these results will help to standardize the study of microplastics in seafood products

Isolation and Extraction of Microplastics from Environmental Samples: An Evaluation of Practical Approaches and Recommendations for Further Harmonisation

Researchers have been identifying microplastics in environmental samples dating back to the 1970s. Today, microplastics are a recognized environmental pollutant attracting a large amount of public and government attention, and in the last few years the number of scientific publications has grown exponentially. An underlying theme within this research field is to achieve a consensus for adopting a set of appropriate procedures to accurately identify and quantify microplastics within diverse matrices. These methods should then be harmonized to produce quantifiable data that is reproducible and comparable around the world. In addition, clear and concise guidelines for standard analytical protocols should be made available to researchers. In keeping with the theme of this special issue the goals of this focal point review are to provide researchers with an overview of approaches to isolate and extract microplastics from different matrices, highlight associated methodological constraints and the necessary steps for conducting procedural controls and quality assurance. Simple samples, including water and sediments with low organic content, can be filtered and sieved. Stepwise procedures require density separation or digestion before filtration. Finally, complex matrices require more extensive steps with both digestion and density adjustments to assist plastic isolation. Implementing appropriate methods with a harmonised approach from sample collection to data analysis will allow comparisons across the research community.acceptedVersio

Toward harmonization and good practices for the study of microplastics in seafood?

International audienceThe massive production of plastics since the 1950’s and the problem of waste mismanagement led to the irrefutable pollution of the open Ocean by plastics, including the tiniest particles called microplastics (MP) and nanoplastics. Since the early seventies, fish with MP in their gut have been described and for that time, the presence of these particles has also been recorded in shellfish, crustaceans and cephalopods. This rise the question on the quality of the product, food safety issues and risk assessment related to the presence of MP in such seafood. To answer these questions, it is important to isolate MP from seafood, using reproducible and reliable methods in order to compare the different studies and accurately estimate the occurrence and levels of MP in seafood. To do so and based on a selection of scientific articles published so far, a review of the current practices of the community was carried out. Multiple aspects were addressed, including MP contamination at the laboratory scale, sampling, extractions of MP, quantification and identification. This work allows pointing out the current limits of the analytical approaches and the needs for improving the methods in order to be able to carry out the most reliable and reproducible analyzes. A final part of this work was dedicated to the concept of “MIMS”, minimal information for the microplastics studies. This check-list, gather essential and desirable points to be addressed from manipulation planning to data processing in order to produce reliable data and facilitate to the intercomparability of the studies

What are the current frontiers and recommendation for the study of microplastics in seafood: proposition of the “MIMS” concept

International audienceSince the 1950’s, mass plastic production and waste mismanagement have resulted in an important pollution of the global environment, including the marine environment. The first mention of seafood contaminated with microplastics (size <5 mm) was recorded in the early 1970’s, and to date numerous studies have been carried out on fish, shellfish and crustaceans. Using published studies , the goal of the current work consists in reporting the numerous methodologies and practices described so far. By examining multiple aspects including problems related to the definition of the term microplastic , contamination of the laboratory environment, sampling and extraction, and quantification and identification, the objective was to point out current limits and the needs to reach reliable and reproducible practices for future studies on microplastics in seafood. A final part is devoted to the minimum information for publication of microplastics studies (MIMS). Globally, practices and methodologies are improving in the most recent publications. However, some gaps are still found in recent literature. Indeed, information on the prevention of contamination, the blank management and the identification of unknown particles are still missing in some studies. Based on the aspects discussed, MIMS can act as a starting point for harmonisation of analyses of microplastics in seafood and also in others matrices

What are the current frontiers and recommendation for the study of microplastics in seafood: proposition of the “MIMS” concept

International audienceSince the 1950’s, mass plastic production and waste mismanagement have resulted in an important pollution of the global environment, including the marine environment. The first mention of seafood contaminated with microplastics (size <5 mm) was recorded in the early 1970’s, and to date numerous studies have been carried out on fish, shellfish and crustaceans. Using published studies , the goal of the current work consists in reporting the numerous methodologies and practices described so far. By examining multiple aspects including problems related to the definition of the term microplastic , contamination of the laboratory environment, sampling and extraction, and quantification and identification, the objective was to point out current limits and the needs to reach reliable and reproducible practices for future studies on microplastics in seafood. A final part is devoted to the minimum information for publication of microplastics studies (MIMS). Globally, practices and methodologies are improving in the most recent publications. However, some gaps are still found in recent literature. Indeed, information on the prevention of contamination, the blank management and the identification of unknown particles are still missing in some studies. Based on the aspects discussed, MIMS can act as a starting point for harmonisation of analyses of microplastics in seafood and also in others matrices

Analyse des microplastiques dans les produits de la pêche : proposition du concept « MIMS »

International audienceDepuis plus de 70 ans, la production de plastique en grande quantité ainsi que les problèmes de gestion des déchets ont conduit à une pollution de l’environnement par ces plastiques et plus particulièrement de l’environnement marin où 80% des déchets retrouvés sont des plastiques. La première mention de produits de la pêche contaminés par des microplastiques (MP) date des années 1970. Depuis lors, de nombreux travaux sont parus portant notamment sur l’étude de coquillages, poissons et crustacées. Basée sur un corpus de publications un travail de revue scientifique a été réalisé afin de compiler l’ensemble des pratiques et méthodologies employées par la communauté. En examinant de multiples aspects : la contamination à l’échelle du laboratoire, l’échantillonnage, l’isolement des MP, leur quantification et leur identification, cette étude a permis de mettre en évidence les limites et les besoins pour améliorer et harmoniser les pratiques pour les futurs travaux sur les produits de la pêche. Une liste de points « essentiels » et « souhaitables » est proposée de façon à fournir les informations minimums pour la réalisation d’études sur les microplastiques (MIMS) dans les produits de la pêche. Les points proposés dans les MIMS, pourraient servir de guide pour une harmonisation des méthodes de travail et des procédures analytiques

Toward harmonization and good practices for the study of microplastics in seafood?

International audienceThe massive production of plastics since the 1950’s and the problem of waste mismanagement led to the irrefutable pollution of the open Ocean by plastics, including the tiniest particles called microplastics (MP) and nanoplastics. Since the early seventies, fish with MP in their gut have been described and for that time, the presence of these particles has also been recorded in shellfish, crustaceans and cephalopods. This rise the question on the quality of the product, food safety issues and risk assessment related to the presence of MP in such seafood. To answer these questions, it is important to isolate MP from seafood, using reproducible and reliable methods in order to compare the different studies and accurately estimate the occurrence and levels of MP in seafood. To do so and based on a selection of scientific articles published so far, a review of the current practices of the community was carried out. Multiple aspects were addressed, including MP contamination at the laboratory scale, sampling, extractions of MP, quantification and identification. This work allows pointing out the current limits of the analytical approaches and the needs for improving the methods in order to be able to carry out the most reliable and reproducible analyzes. A final part of this work was dedicated to the concept of “MIMS”, minimal information for the microplastics studies. This check-list, gather essential and desirable points to be addressed from manipulation planning to data processing in order to produce reliable data and facilitate to the intercomparability of the studies