From effect-directed anaysis to metabolomic assessment: How do the main emerging contaminants released into the Adour estuary affect glass eels (Anguilla anguilla)?

Abstract

Since countless xenobiotic compounds are being found in the environment, ecotoxicology faces an astounding challenge in identifying toxicants. The combination of high-throughput in vivo/in vitro bioassays with high-resolution chemical analysis is an effective way to elucidate the cause-effect relationship. However, these combined strategies imply an enormous workload that can hinder their implementation in routine analysis. The first aim of this thesis was to develop a new high throughput screening method to implement the sea urchin embryo test in effect-directed analysis. This way, we developed a novel predictive expert system, the SETApp, which can be used to automatically quantify the two endpoints of the sea urchin embryo test from a given image set. We demonstrated that chemometrics, and especially multivariate linear classification models, can be successfully implemented in bioassay automation to avoid the cumbersome measurement of embryo sizes and malformation levels. In addition, we have also shown the efficiency of this HTS in a very demanding scenario, the EDA of Bayonne's (Basque Country, France) Pont de l'aveugle WWTP effluent. This EDA study concluded that the SETApp is an efficient, fast, cost-effective, and reproducible tool that can approach EDA to routine analysis.On the other hand, the presence of these contaminants of emerging concern (CECs) in the aquatic environment directly impacts water-living organisms and can alter their living functions. These compounds are often metabolized and excreted, but they can also be accumulated and spread through the food chain. The metabolized contaminants can also lead to the formation of new compounds with unknown toxicity and bioaccumulation potential. In the second study of this work, we studied the occurrence, bioconcentration, and biotransformation of CECs in glass eels (Anguilla anguilla) using UHPLC-HRMS.Finally, in our third study, we focused on the impact assessment of the selected emerging contaminants in glass eels by means of metabolomics. This approach not only allowed us to evaluate the toxicity of these contaminants but also to gain insight into the metabolic differences between migrant and non-migrant glass eels.