Abstract
Spanning more than 70% of the Earth's surface, the oceans constitute a vast and enigmatic realm that holds boundless significance in shaping the Earth's climate, supporting diverse life forms and providing essential resources for human sustenance and well-being. Unfortunately, human activities have also largely altered the oceans and their biodiversity. In recent years, to investigate how organisms respond to stress, scientists have harnessed advanced technologies like proteomics, which allows the simultaneous analysis of hundreds to thousands of proteins, offering insights into the dynamic organism’s physiological processes. Proteins act as effectors in cellular responses and are at the interface between the genome and the phenotype of an organism, making proteomics a powerful tool for comprehensively assessing the impact of environmental stress on marine species.The main objective of this thesis was to delve into the physiological responses of various marine species (including green sea turtles, sardines, gilthead seabream, and yellow gorgonians) when confronted with different stressors, with particular emphasis on inorganic contamination and marine heatwaves. To achieve this, a proteomic approach was employed along with conventional biomarkers. The results unveiled similar molecular mechanisms across diverse species. These mechanisms appear to be interconnected through a shared stress signalling network, primarily focused on preserving genomic and macromolecular integrity during stress. Additionally, altered biological pathways in response to stress across all studied species can be assigned to several large functions, including metabolism, cellular organization, the immune system, stress response and cellular transport and localization. There were also fewer representations of pathways involved in cellular development and cell cycle and signalling pathways. Moreover, the thesis identified biomarkers essential for monitoring the health of the various studied species. Traditional stress indicators, such as body condition, lipid reserves, and plasma enzymes, exhibited limited responses to contamination, whereas proteomic methods revealed alterations in 551 biological pathways, highlighting their heightened sensitivity in studying the effects of contaminants.In perspective, various "omics" technologies offer insights into diverse aspects, including the epigenome, transcriptome, and metabolome. These multi-omics approaches hold the potential to connect genotype, phenotype, and the environment. By integrating data from these different omics layers in future research, we can gain a comprehensive understanding of biological systems, uncover regulatory mechanisms, identify biomarkers, and elucidate intricate interactions among genes, proteins, and metabolites. Establishing time-series data is crucial to track the evolution of these responses over time. Nevertheless, significant scientific challenges remain, such as mitigating biases between different omics layers, integrating multi-omics data, and developing predictive models for complex datasets.