The growing demand for critical metals has accelerated interest in deep-sea mining, yet its environmental consequences remain poorly understood, particularly for pelagic ecosystems that may be exposed to mining-derived discharges. Deep-sea mining releases a complex mixture of suspended particles, nutrients, and trace metals whose ecological impacts are governed not only by their concentrations but also by their chemical behaviour and bioavailability. In this presentation, I will highlight recent advances from our group and the wider research community on the impacts of deep-sea mining on seawater chemistry and pelagic ecosystems. Particular emphasis will be placed on the behaviour and bioavailability of mining-derived contaminants, their effects on marine microorganisms and zooplankton, and the mechanisms underlying nutrient enrichment, metal toxicity, and ecological responses across trophic levels. Finally, I will discuss how these emerging findings can improve ecological risk assessment and provide a scientific basis for environmental management and the development of regulatory frameworks for deep-sea mining.