Trophic ecology of icefishes (Notothenioidei, Perciformes) in a context of climate change

The Southern Ocean currently undergoes major environmental modifications related to climate change. When faced with environmental changes, all organisms are expected to have some intrinsic capacity to adapt their ecological habits to their new life conditions. Currently, biological traits of many Antarctic species are still unknown and we need such information to assess their capacity to adapt to natural and anthropogenic perturbations. Notothenioidei (Perciformes), or icefishes, are endemic to the Southern Ocean and they are an important trophic component of these marine ecosystems. Here we used stable isotopes ratios of carbon (δ13C) and nitrogen (δ15N) of two well represented genera of icefishes (Trematomus and Lepidonotothen) sampled in 2002/2004 and/or in 2015/2016 to better understand their resources partitioning and the influence of environmental changes on their trophic ecology. Isotopic niches (which are a proxy of the realized ecological niches) were modeled using the SIBER (Stable Isotope Bayesian Ellipses in R) R-package. Our results revealed a great variation in isotopic compositions among icefishes, suggesting that they exploit a wide array of resources. The overlap between the isotopic niches of Trematomus and Lepidonotothen genera in 2002/2004 highlights a possible past competition for resources. Moreover, temporal evolution of niches suggests taxon-specific ecological plasticity in response to variation in environmental parameters and/or in prey availability. An increase in resources partitioning between the two genera was observed over the studied period. In the future, it would be interesting to use mixing models including isotopic composition of potential preys to identify possible changes in their trophic ecology.Refugia and Ecosystem Tolerance in the Southern Ocean (RECTO

Influence of environmental conditions on Antarctic Notothenioid trophic ecology in a context of global climate change

The Southern Ocean currently undergoes major environmental modifications related to climate change such as changes in the sea ice cover, temperature and acidification. When faced with environmental changes, all organisms are expected to have some intrinsic capacity to adapt their ecological habits to their new life conditions. Currently, biological traits of many Antarctic species are still unknown and we need such information to assess their capacity to adapt to natural and anthropogenic perturbations. Notothenioidei (Perciformes), or icefishes, are endemic to the Southern Ocean and they are an important trophic component of these marine ecosystems. To better understand their resources partitioning and the influence of environmental changes on their trophic ecology, we used muscle stable isotopes ratios of carbon (δ13C) and nitrogen (δ15N) of two widespread genera of icefishes (Trematomus and Lepidonotothen) sampled in 2002/2004 and/or in 2015/2016. Isotopic niches (which are a proxy of the realized ecological niches) were modeled using the SIBER (Stable Isotope Bayesian Ellipses in R) R-package. For the two sampling periods, our results revealed a great variation in isotopic compositions among Notothenioid fishes, suggesting that they exploit a wide array of resources. The overlap between the isotopic niches of Trematomus and Lepidonotothen genera in 2002/2004 highlights a possible past competition for resources. Moreover, temporal evolution of niches suggests taxon-specific ecological plasticity in response to variation in environmental parameters and/or in prey availability. An increase in resources partitioning between the two genera was observed over the studied period. In the future, it would be interesting to complete our results with a stomach content analysis and to use mixing models including isotopic composition of potential preys to identify possible changes in their trophic ecology. This research was funded by the Belgian Federal Science Policy OfficevERSO and RECTO projects (http://www.rectoversoprojects.be

delta13C and delta15N measurements in Antarctic Notothenioid fishes: variation of their trophic ecology in a context of climate change

Refugia and ecosystem tolerance in the Southern Ocean (RECTO) - Research project BR/154/A1/RECT

Advancing environmental monitoring across the water continuum combining biomarker analysis in multiple sentinel species: A case study in the Seine-Normandie Basin (France)

Nowadays, biomarkers are recognized as valuable tools to complement chemical and ecological assessments in biomonitoring programs. They provide insights into the effects of contaminant exposures on individuals and establish connections between environmental pressure and biological response at higher levels. In the last decade, strong improvements in the design of experimental protocols and the result interpretation facilitated the use of biomarker across wide geographical areas, including aquatic continua. Notably, the statistical establishment of reference values and thresholds enabled the discrimination of contamination effects in environmental conditions, allowed interspecies comparisons, and eliminated the need of a reference site. The aim of this work was to study freshwater -estuarine -coastal water continua by applying biomarker measurements in multi -species caged organisms. During two campaigns, eight sentinel species, encompassing fish, mollusks, and crustaceans, were deployed to cover 25 sites from rivers to the sea. As much as possible, a common methodology was employed for biomarker measurements (DNA damage and phagocytosis efficiency) and data interpretation based on guidelines established using reference values and induction/inhibition thresholds (establishment of three effect levels). The methodology was successfully implemented and allowed us to assess the environmental quality. Employing multiple species per site enhances confidence in observed trends. The results highlight the feasibility of integrating biomarker-based environmental monitoring programs across a continuum scale. Biomarker results align with Water Framework Directive indicators in cases of poor site quality. Additionally, when discrepancies arise between chemical and ecological statuses, biomarker findings offer a comprehensive perspective to elucidate the disparities. Presented as a pilot project, this work contributes to gain insights into current biomonitoring needs, providing new questions and perspectives

Stratégie de déploiement de biomarqueurs en appui à la surveillance de la qualité des masses d’eau, le long du continuum bassin verssant-littoral

International audienc

Advancing environmental monitoring across the water continuum combining biomarker analysis in multiple sentinel species: A case study in the Seine-Normandie Basin (France)

International audienceNowadays, biomarkers are recognized as valuable tools to complement chemical and ecological assessments in biomonitoring programs. They provide insights into the effects of contaminant exposures on individuals and establish connections between environmental pressure and biological response at higher levels. In the last decade, strong improvements in the design of experimental protocols and the result interpretation facilitated the use of biomarker across wide geographical areas, including aquatic continua. Notably, the statistical establishment of reference values and thresholds enabled the discrimination of contamination effects in environmental conditions, allowed interspecies comparisons, and eliminated the need of a reference site.The aim of this work was to study freshwater-estuarine-coastal water continua by applying biomarker measurements in multi-species caged organisms. During two campaigns, eight sentinel species, encompassing fish, mollusks, and crustaceans, were deployed to cover 25 sites from rivers to the sea. As much as possible, a common methodology was employed for biomarker measurements (DNA damage and phagocytosis efficiency) and data interpretation based on guidelines established using reference values and induction/inhibition thresholds (establishment of three effect levels).The methodology was successfully implemented and allowed us to assess the environmental quality. Employing multiple species per site enhances confidence in observed trends. The results highlight the feasibility of integrating biomarker-based environmental monitoring programs across a continuum scale. Biomarker results align with Water Framework Directive indicators in cases of poor site quality. Additionally, when discrepancies arise between chemical and ecological statuses, biomarker findings offer a comprehensive perspective to elucidate the disparities. Presented as a pilot project, this work contributes to gain insights into current biomonitoring needs, providing new questions and perspectives

Projet SASHIMI. Surveillance active de l’impact de la pression chimique par des biomarqueurs

International audienc