Spatial analysis of demersal food webs through integration of eDNA metabarcoding with fishing activities

The evaluation of the status of marine communities, and especially the monitoring of those heavily exploited by fisheries, is a key, challenging task in marine sciences. Fishing activities are a major source of disruption to marine food webs, both directly, by selectively removing components at specific trophic levels (TL), and indirectly, by altering habitats and production cycles. Food web analysis can be very useful in the context of an Ecosystem Approach to Fisheries, but food web reconstructions demand large and expensive data sets, which are typically available only for a small fraction of marine ecosystems. Recently, new technologies have been developed to easily, quickly and cost-effectively collect environmental DNA (eDNA) during fishing activities. By generating large, multi-marker metabarcoding data from eDNA samples obtained from commercial trawlers, it is possible to produce exhaustive taxonomic inventories for the exploited ecosystems, which are suitable for food-web reconstructions. Here, we integrate and re-analyse the data of a recent study in which the α diversity was investigated using the eDNA opportunistically collected during fishing operations. Indeed, we collect highly resolved information on species feeding relationships to reconstruct the food webs at different sites in the Strait of Sicily (Mediterranean Sea) from eDNA and catch data. After observing that the trophic networks obtained from eDNA metabarcoding data are more consistent with the available knowledge, a set of food web indicators (species richness, number of links, direct connectance and generality) is computed and analysed to unravel differences in food webs structure through different areas (spatial variations). Species richness, number of links and generality (positively) and direct connectance (negatively) are correlated with increasing distance from the coast and fishing effort intensity. The combined effects of environmental gradients and fishing effort on food web structure at different study sites are then examined and modelled. Taken together, these findings indicate the suitability of eDNA metabarcoding to assist and food web analysis, obtain several food web-related ecological indicators, and tease out the effect of fishing intensity from the environmental gradients of marine ecosystems

Spatial analysis of demersal food webs through integration of eDNA metabarcoding with fishing activities

The evaluation of the status of marine communities, and especially the monitoring of those heavily exploited by fisheries, is a key, challenging task in marine sciences. Fishing activities are a major source of disruption to marine food webs, both directly, by selectively removing components at specific trophic levels (TL), and indirectly, by altering habitats and production cycles. Food web analysis can be very useful in the context of an Ecosystem Approach to Fisheries, but food web reconstructions demand large and expensive data sets, which are typically available only for a small fraction of marine ecosystems. Recently, new technologies have been developed to easily, quickly and cost-effectively collect environmental DNA (eDNA) during fishing activities. By generating large, multi-marker metabarcoding data from eDNA samples obtained from commercial trawlers, it is possible to produce exhaustive taxonomic inventories for the exploited ecosystems, which are suitable for food-web reconstructions. Here, we integrate and re-analyse the data of a recent study in which the α diversity was investigated using the eDNA opportunistically collected during fishing operations. Indeed, we collect highly resolved information on species feeding relationships to reconstruct the food webs at different sites in the Strait of Sicily (Mediterranean Sea) from eDNA and catch data. After observing that the trophic networks obtained from eDNA metabarcoding data are more consistent with the available knowledge, a set of food web indicators (species richness, number of links, direct connectance and generality) is computed and analysed to unravel differences in food webs structure through different areas (spatial variations). Species richness, number of links and generality (positively) and direct connectance (negatively) are correlated with increasing distance from the coast and fishing effort intensity. The combined effects of environmental gradients and fishing effort on food web structure at different study sites are then examined and modelled. Taken together, these findings indicate the suitability of eDNA metabarcoding to assist and food web analysis, obtain several food web-related ecological indicators, and tease out the effect of fishing intensity from the environmental gradients of marine ecosystems

Étude des polluants atmosphériques émis dans deux centres de stockage des ordures ménagères

International audienceWe have a lack of knowledge about the existence of risks for the health related with domestic garbage elimination in municipal solid waste landfills. In the aim of obtaining more data, a multidisciplinary approach has been developed and applied to two sites:- chemical and microbiological metrology of sources;- metrology of selected pollutants and microorganism analysis in the ambient air at several places of work, as well as in immediate periphery and close to the first dwellings;- measure of these pollutants in lichens;- experimental survey in laboratory of rats living on landfill soils;- survey of health parameters in workers of the sites compared to non exposed men employed in other commercial of industrial activities.In fact, concentrations of pollutants are low, with the exception of total dusts, manganese and microorganisms. The volatile organic compounds (VOC) are present on the celle in operation, because of the traffic of diesel trucks. The same observation is done for PAH, which are closed to the urban environment levels. High total dusts levels have been measured (but the levels of alveolar dusts were low). Manganese is the more representative metal, which is also recovered in lichens. Concentrations of microorganisms are high (100 at 1000 times what one recovers in classic environment), with the presence of pollution picks, and characteristic monomorphic bacteria and fungi (Aspergillus and Penicillium).Respiratory symptoms and cutaneous irritation are more often observed among landfill workers than among non-exposed workers, but no perturbation of the lung function was detected among them. Studies led on laboratory rats showed the existence of inflammation of the pulmonary tissues. Enzymatic induction (CYP1A and CYP2B) in respiratory and hepatic cells was observed. Observations of comets indicate a transient aggression, which was compatible with inhalation of COV.This study brings several elements of knowledge on the ambient air pollution in municipal solid waste landfill, and their possible effects on health. It would be necessary to continue the investigations particularly on the sanitary effect of the microbiological pollution.L’existence de risques pour la santé associés à l’élimination des ordures ménagères en décharge contrôlée est encore mal évaluée. Devant les données très parcellaires dont on dispose, une approche pluridisciplinaire établie en plusieurs étapes a été conçue par le Réseau Santé Déchets (RSD) et appliquée à deux sites :- métrologie chimique et microbiologique des sources d’émission ;- métrologie des polluants sélectionnés et des microorganismes aux postes de travail et en ambiance, ainsi qu’en périphérie immédiate et à proximité des premières habitations ;- mesure de ces mêmes polluants dans les lichens présents sur les sites ou transplantés ;- étude expérimentale en laboratoire sur des rats au contact des sols prélevés sur les deux sites ;- étude des paramètres de santé et de l’existence ou non de troubles chez les salariés des sites comparés à des salariés non exposés issus d’autres activités.Les concentrations mesurées dans les ambiances aériennes des sites et à proximité sont dans l’ensemble faibles.Les composés organiques volatils (COV) sont présents, à des niveaux faibles, sur l'alvéole en exploitation, liés en particulier au trafic des engins diesel. Les niveaux de HAP particulaires sont de l'ordre de ceux qui sont observés en milieu urbain. Des niveaux très élevés en poussières totales (mais faibles pour les poussières alvéolaires) ont été mesurés. Le manganèse est le métal le plus représenté, il est retrouvé également dans les lichens. Les concentrations en micro-organisme sont élevées soit 100 à 1000 fois ce que l'on retrouve en environnement classique. La flore est caractéristique des milieux de traitement du déchet avec un aspect monomorphe (champignons de type Aspergillus ou Penicillium).Une symptomatologie fonctionnelle témoignant d'une atteinte irritative ou immunoallergique des voies respiratoires et du revêtement cutanéo-muqueux est observée chez les salariés des sites étudiés, sans qu'il n'y ait perturbation de la fonction respiratoire. Aucun trouble clinique n'est mis en évidence. Les études menées sur les rats de laboratoire ont montré l'existence de foyers inflammatoires des tissus pulmonaires (chez les bêtes autopsiées) et d'une réponse en terme d'induction enzymatique (CYP1A et CYP2B) surtout respiratoire. Le test génotoxique des comètes indique une atteinte transitoire et compatible avec l'inhalation de COV.Cette étude, même si elle ne représente qu'un instantané de la situation des deux sites étudiés, apporte les premiers éléments de connaissance sur les effluents aériens de décharges d'ordures ménagères, et leurs possibles effets sur la santé. Elle ouvre sur des questions qu'il faudrait pouvoir approfondir, en particulier l'impact sanitaire des micro-organismes

DataSheet_1_Spatial analysis of demersal food webs through integration of eDNA metabarcoding with fishing activities.docx

The evaluation of the status of marine communities, and especially the monitoring of those heavily exploited by fisheries, is a key, challenging task in marine sciences. Fishing activities are a major source of disruption to marine food webs, both directly, by selectively removing components at specific trophic levels (TL), and indirectly, by altering habitats and production cycles. Food web analysis can be very useful in the context of an Ecosystem Approach to Fisheries, but food web reconstructions demand large and expensive data sets, which are typically available only for a small fraction of marine ecosystems. Recently, new technologies have been developed to easily, quickly and cost-effectively collect environmental DNA (eDNA) during fishing activities. By generating large, multi-marker metabarcoding data from eDNA samples obtained from commercial trawlers, it is possible to produce exhaustive taxonomic inventories for the exploited ecosystems, which are suitable for food-web reconstructions. Here, we integrate and re-analyse the data of a recent study in which the α diversity was investigated using the eDNA opportunistically collected during fishing operations. Indeed, we collect highly resolved information on species feeding relationships to reconstruct the food webs at different sites in the Strait of Sicily (Mediterranean Sea) from eDNA and catch data. After observing that the trophic networks obtained from eDNA metabarcoding data are more consistent with the available knowledge, a set of food web indicators (species richness, number of links, direct connectance and generality) is computed and analysed to unravel differences in food webs structure through different areas (spatial variations). Species richness, number of links and generality (positively) and direct connectance (negatively) are correlated with increasing distance from the coast and fishing effort intensity. The combined effects of environmental gradients and fishing effort on food web structure at different study sites are then examined and modelled. Taken together, these findings indicate the suitability of eDNA metabarcoding to assist and food web analysis, obtain several food web-related ecological indicators, and tease out the effect of fishing intensity from the environmental gradients of marine ecosystems.</p