Human activities severely impacted the marine environment, threatening ecosystems and human health. Plastic pollution and agricultural contamination are major contributors. Plastics account for about 80% of marine litter, with global production raising from 1.7 to 299 million tonnes between the 1950s and 2014. The COVID-19 pandemic worsened the situation by increasing plastic demand. Microplastics (MP), particles smaller than 5 mm, proliferated, posing significant risks to marine life and ecosystems. By 2050, MPs were predicted to outnumber fish in the oceans, increasing the incidence of lethal entanglement and ingestion by sea animals by 40%. MP also absorb toxic chemicals, which enter into the food chain, raising exposure risks. Agricultural products, such as organophosphorus pesticides (OPs), also contaminate the oceans. Chlorpyrifos, a widely used OP, cause neurotoxic effects in non-target organisms. Alongside plastics and toxins, global warming and ocean acidification further threaten marine life. Surface and coastal water temperatures are expected to rise by 1.8-4°C by the century's end, while ocean pH might drop by 0.2-0.5 units in the next 60 years, exacerbating stress on ecosystems and increasing contaminant toxicity. Despite efforts to mitigate these impacts, information on the combined effects of multiple stressors on marine life remains scarce. App-MariE pioneered the study of the joint impact of MP and an OP, Chlorpyrifos, on the sentinel species P. lividus under climate change scenarios. P. lividus, a key component of marine ecosystems, was chosen due to its simplicity, low cost, and regulatory advantages for bioassays. The project aimed to standardize bioassays to evaluate the complex effects of multiple stressors and link early life stage effects to adult impacts (Objective 1). Additionally, App-MariE sought to understand the molecular mechanisms triggered by pollutant combinations and their broader implications across species, providing insights for predicting ecosystem impacts (Objective 2). The project proposed a multidisciplinary approach to manage data and foster cooperation between researchers, industries, and governments (Objective 3).
As a result of App-MariE, the traditional sea urchin embryo test was improved by incorporating data on morphology, gene expression, and informatics applications, making it more predictive and capable of providing detailed information about the toxicity of pollutant mixtures. Additionally, the project demonstrated that research should focus on studying the impact of pollutants within mixtures, which is more realistic than evaluating each contaminant or stressor individually. Finally, the integration of applied informatics and standardized operating procedures (SOPs) for data analysis made the sea urchin embryo test easier to perform and more reproducible. This will enable others, even those without prior experience, to analyze pollutant mixtures using the App-MariE approach.
