Assessment of trace element contamination and its effects on the larval and adult stages of Paracentrotus lividus

Trace elements are among the most common contaminants in the marine ecosystem. Beyond critical thresholds, all trace elements present a potential danger that can lead to disturbances at the cellular and individual level, but also at the population or ecosystem level. In the Mediterranean Sea, Corsica Island has long been considered an area of low anthropic pressure. Due to its ecological characteristics, its high tolerance to contaminants and its ability to bioaccumulate trace elements, the sea urchin Paracentrotus lividus (Lamarck, 1816) is recognized as a bioindicator. The aim of this thesis was to better understand the variations of trace element contamination in Corsica and their effects on an emblematic organism, Paracentrotus lividus. An assessment of the contamination of classical and emerging trace elements was conducted on sea urchin gonads. In this context, several samples were collected in order to determine the main trace elements susceptible to be bioaccumulated by the adult sea urchin and the spatio-temporal variations of these contaminants. This research has highlighted areas in Corsica with higher trace element concentrations due to geochemical backgrounds associated with anthropogenic pressures. Seasonal variations were also identified with lower concentrations during the summer season. These variations are mainly due to the reproduction cycle of the sea urchin and show the importance of biotic factors in the evaluation of contamination levels. Biochemical analyses of adult sea urchins suggest that the oxidative stress induced by the measured contaminations has no direct impact on their health. Bioassays performed on larval stages of sea urchins were used to evaluate the effects of several trace element contaminations. These contaminations induced malformations and a slowing of the development. In addition, research on the stress responses of the different larval stages has highlighted the high capacity of larvae to respond to oxidative stress, but also the importance of spawners in studies using sea urchin larvae. These innovative experiments are the first to investigate the effects of such important combinations of trace elements on the entire larval cycle of the sea urchin. This present work could strengthen other tools for diagnosing and monitoring coastal water quality in order to improve the ecological quality of marine waters

Stress response to trace elements mixture of different embryo-larval stages of Paracentrotus lividus

peer reviewedThis study investigated for the first time the oxidative biomarkers responses in all larval stages of sea urchin. The contamination effects were reproduced by using contaminated seawater to concentrations measured in the area adjacent to an old asbestos mine at factors of 5 and 10. The results suggested that the concentrations were not sufficiently high to induce a major oxidative stress. The biometric differences make this method a more sensitive approach for assessing the effects on sea urchin larvae. Measurements of specific activities of antioxidant enzymes at each stage suggested a high capacity of the larvae to respond to oxidative stress. This normal activity of the organism must be considered in future research. This work also highlighted the importance of spawners provenance in ecotoxicological studies. These data are essential to better understand the stress responses of sea urchin larvae and provide baseline information for later environmental assessment research

Evaluation des contaminations en éléments traces et leurs effets sur les stades larvaires et adulte de Paracentrotus lividus

Trace elements are among the most commoncontaminants in the marine ecosystem. Beyond critical thresholds, all trace elements present apotential danger that can lead to disturbances at the cellular and individual level, but also at thepopulation or ecosystem level. In the Mediterranean Sea, Corsica Island has long been considered anarea of low anthropic pressure. Due to its ecological characteristics, its high tolerance to contaminantsand its ability to bioaccumulate trace elements, the sea urchin Paracentrotus lividus (Lamarck, 1816)is recognized as a bioindicator. The aim of this thesis was to better understand the variations of traceelement contamination in Corsica and their effects on an emblematic organism, Paracentrotus lividus.An assessment of the contamination of classical and emerging trace elements was conducted on seaurchin gonads. In this context, several samples were collected in order to determine the main trace elements susceptible to be bioaccumulated by the adult sea urchin and the spatio-temporal variationsof these contaminants. This research has highlighted areas in Corsica with higher trace elementconcentrations due to geochemical backgrounds associated with anthropogenic pressures. Seasonalvariations were also identified with lower concentrations during the summer season. These variationsare mainly due to the reproduction cycle of the sea urchin and show the importance of biotic factorsin the evaluation of contamination levels. Biochemical analyses of adult sea urchins suggest that theoxidative stress induced by the measured contaminations has no direct impact on their health.Bioassays performed on larval stages of sea urchins were used to evaluate the effects of several traceelement contaminations. These contaminations induced malformations and a slowing of thedevelopment. In addition, research on the stress responses of the different larval stages hashighlighted the high capacity of larvae to respond to oxidative stress, but also the importance ofspawners in studies using sea urchin larvae. These innovative experiments are the first to investigatethe effects of such important combinations of trace elements on the entire larval cycle of the seaurchin. This present work could strengthen other tools for diagnosing and monitoring coastal waterquality in order to improve the ecological quality of marine waters.Les éléments traces font partis des contaminants les plus répandus dans l’écosystème marin. Au-dessus de seuils critiques, tous les éléments traces présentent un danger potentiel pouvant entraîner des perturbations à l’échelle cellulaire et individuelle, mais aussi au niveau de la population ou de l’écosystème. En Méditerranée, la Corse a longtemps été considérée comme une zone subissant de faibles pressions anthropiques. De par ses caractéristiques écologiques, sa haute tolérance aux contaminants et sa capacité à bioaccumuler des éléments traces, l’oursin violet Paracentrotus lividus (Lamarck, 1816) est reconnu en tant que bioindicateur. L’objectif de ce travail de thèse a consisté à mieux comprendre les variations des contaminations en éléments traces en Corse ainsi que leurs effets chez un organisme emblématique,Paracentrotus lividus. Une évaluation de la contamination en éléments traces classiques et émergents a été menée sur les gonades d’oursins. Dans ce cadre, plusieurs prélèvements en mer ont été effectués afin de déterminer les principaux éléments traces susceptibles d’être bioaccumulés par l'oursin adulte et les variations spatio-temporelles de ces contaminants. Ces travaux ont mis en évidence des régions en Corse présentant des concentrations en éléments traces plus élevées dues aux fonds géochimiques associés aux pressions anthropiques. Des variations saisonnières ont également été décelées avec des concentrations plus faibles durant la saison estivale. Ces variations sont notamment liées au cycle de reproduction de l’oursin et démontrent l’importance des facteurs biotiques dans l’évaluation des niveaux de contamination. Les analyses biochimiques des oursins adultes suggèrent que le stress oxydatif induit par les contaminations mesurées n'a pas d'impact direct sur leur santé. Les bioessais menés sur les stades larvaires de l’oursin ont permis d’évaluer les effets de différentes contaminations en éléments traces. Ces contaminations ont induit des malformations ainsi qu’un ralentissement de la croissance, voire une inhibition du développement larvaire. En parallèle, des recherches sur les réponses au stress des différents stades larvaires ont permis de souligner la grande capacité des larves à répondre au stress oxydatif, mais également l’importance des géniteurs dans les études utilisant les larves d’oursin. Ces expérimentations innovantes sont les premières à s’intéresser aux effets d’une combinaison aussi importante d’éléments traces sur l’ensemble du cycle larvaire de l’oursin. Le présent travail pourrait renforcer d’autres outils de diagnostic et de suivi de la qualité des eaux côtières en vue d’améliorer la qualité écologique des eaux marines

Assessment of trace element contamination and its effects on the larval and adult stages of Paracentrotus lividus

Les éléments traces font partis des contaminants les plus répandus dans l’écosystème marin. Au-dessus de seuils critiques, tous les éléments traces présentent un danger potentiel pouvant entraîner des perturbations à l’échelle cellulaire et individuelle, mais aussi au niveau de la population ou de l’écosystème. En Méditerranée, la Corse a longtemps été considérée comme une zone subissant de faibles pressions anthropiques. De par ses caractéristiques écologiques, sa haute tolérance aux contaminants et sa capacité à bioaccumuler des éléments traces, l’oursin violet Paracentrotus lividus (Lamarck, 1816) est reconnu en tant que bioindicateur. L’objectif de ce travail de thèse a consisté à mieux comprendre les variations des contaminations en éléments traces en Corse ainsi que leurs effets chez un organisme emblématique,Paracentrotus lividus. Une évaluation de la contamination en éléments traces classiques et émergents a été menée sur les gonades d’oursins. Dans ce cadre, plusieurs prélèvements en mer ont été effectués afin de déterminer les principaux éléments traces susceptibles d’être bioaccumulés par l'oursin adulte et les variations spatio-temporelles de ces contaminants. Ces travaux ont mis en évidence des régions en Corse présentant des concentrations en éléments traces plus élevées dues aux fonds géochimiques associés aux pressions anthropiques. Des variations saisonnières ont également été décelées avec des concentrations plus faibles durant la saison estivale. Ces variations sont notamment liées au cycle de reproduction de l’oursin et démontrent l’importance des facteurs biotiques dans l’évaluation des niveaux de contamination. Les analyses biochimiques des oursins adultes suggèrent que le stress oxydatif induit par les contaminations mesurées n'a pas d'impact direct sur leur santé. Les bioessais menés sur les stades larvaires de l’oursin ont permis d’évaluer les effets de différentes contaminations en éléments traces. Ces contaminations ont induit des malformations ainsi qu’un ralentissement de la croissance, voire une inhibition du développement larvaire. En parallèle, des recherches sur les réponses au stress des différents stades larvaires ont permis de souligner la grande capacité des larves à répondre au stress oxydatif, mais également l’importance des géniteurs dans les études utilisant les larves d’oursin. Ces expérimentations innovantes sont les premières à s’intéresser aux effets d’une combinaison aussi importante d’éléments traces sur l’ensemble du cycle larvaire de l’oursin. Le présent travail pourrait renforcer d’autres outils de diagnostic et de suivi de la qualité des eaux côtières en vue d’améliorer la qualité écologique des eaux marines.Trace elements are among the most commoncontaminants in the marine ecosystem. Beyond critical thresholds, all trace elements present apotential danger that can lead to disturbances at the cellular and individual level, but also at thepopulation or ecosystem level. In the Mediterranean Sea, Corsica Island has long been considered anarea of low anthropic pressure. Due to its ecological characteristics, its high tolerance to contaminantsand its ability to bioaccumulate trace elements, the sea urchin Paracentrotus lividus (Lamarck, 1816)is recognized as a bioindicator. The aim of this thesis was to better understand the variations of traceelement contamination in Corsica and their effects on an emblematic organism, Paracentrotus lividus.An assessment of the contamination of classical and emerging trace elements was conducted on seaurchin gonads. In this context, several samples were collected in order to determine the main trace elements susceptible to be bioaccumulated by the adult sea urchin and the spatio-temporal variationsof these contaminants. This research has highlighted areas in Corsica with higher trace elementconcentrations due to geochemical backgrounds associated with anthropogenic pressures. Seasonalvariations were also identified with lower concentrations during the summer season. These variationsare mainly due to the reproduction cycle of the sea urchin and show the importance of biotic factorsin the evaluation of contamination levels. Biochemical analyses of adult sea urchins suggest that theoxidative stress induced by the measured contaminations has no direct impact on their health.Bioassays performed on larval stages of sea urchins were used to evaluate the effects of several traceelement contaminations. These contaminations induced malformations and a slowing of thedevelopment. In addition, research on the stress responses of the different larval stages hashighlighted the high capacity of larvae to respond to oxidative stress, but also the importance ofspawners in studies using sea urchin larvae. These innovative experiments are the first to investigatethe effects of such important combinations of trace elements on the entire larval cycle of the seaurchin. This present work could strengthen other tools for diagnosing and monitoring coastal waterquality in order to improve the ecological quality of marine waters

Spatial variations in trace element concentrations of the sea urchin, Paracentrotus lividus, a first reference study in the Mediterranean Sea

A study on Trace Elements (TE) from sea urchin gonads has been conducted in the western Mediterranean Sea. Contamination data were used to determine a Trace Method Pollution Index (TEPI). TE concentrations varied considerably depending on the location of the sampling stations. The results showed that five trace elements (Zn, Fe, As, Al, Cu) are ubiquitous. The geographical area considered (Corsica) represents an important range of environmental conditions and types of pressure that can be found in the western Mediterranean Sea. TEPI was used to classify the studied sites according to their degree of contamination and allowed reliable comparison of TE contamination between local and international sites. TE contamination of the western Mediterranean Seadisplayed a north-to-south gradient, from the Italian coasts down through the insular Corsican coasts to the north African littoral. Due to the increasing environmental pressure on the Mediterranean Sea, a regular monitoring of TE levels in marine organisms is necessary to prevent any further environmental deterioration

Seasonal change in trace element concentrations of Paracentrotus lividus: Its use as a bioindicator

An assessment of classical and emerging trace element contamination was conducted on gonads of the sea urchin Paracentrotus lividus (Lamarck, 1819), in Corsica (Western Mediterranean). The aim of this study was to evaluate the contamination levels at different sites by following the seasonal variation of 22 trace elements. The sea urchins analyzed were taken in 2017 from reference and more impacted sites in four Corsican areas. The results obtained shown the importance of biotic factors such as gender, reproduction and the way of life. Variations have been highlighted with lower trace element concentrations during the summer season. This is mainly due to a dilution phenomenon resulting from gametogenesis. The pollution index (TEPI) was determined and highlighted differences in contamination levels at the various sites. This work could provide additional support for other tools for the diagnosis and monitoring of coastal water quality. It provides useful new data to enable managers to act at the source and reduce degradation in order to improve the ecological quality of marine waters