Warming coupled with uranium exposure can alter the marine microbial community and induce toxin accumulation in shellfish.

This study explores the coupled effects of warming and uranium exposure on marine microbial communities and assesses their potential impact on shellfish toxicity. Different temperature conditions (20 °C and 30 °C) and uranium exposure levels (a controlled setting, 25 μM, and 50 μM) were simulated in an artificial climate chamber. The results indicate that the coupling of warming and uranium exposure significantly altered the water system's properties, including its pH, dissolved oxygen, redox potential, and conductivity. The uranium exposure also significantly altered the diversity and composition of the seawater's microbial community, increasing Pseudomonadota, Flavobacteriia, and Marivita while decreasing Gammaproteobacteria. When subjected to warming and uranium exposure, toxin-producing dinoflagellates exhibited upregulation in toxin anabolism and cell signaling at the gene level, leading to a 25 % increase in toxic synthesis compared to the control group. These changes were positively correlated with temperature and pollution levels, suggesting that uranium exposure and warming promote toxin accumulation in dinoflagellates. The study highlights that seawater warming and uranium exposure synergistically affect microbial community diversity and shellfish toxicity, potentially inducing toxin accumulation in shellfish. Thus, under the conditions of global climate change, uranium exposure may increase the risk of toxin accumulation in shellfish living in seawater.