The study, published in the KeAi journal Environmental Chemistry and Ecotoxicology, found that MNPs at a concentration of 200 μg/L caused a 51.8% and 74.4% increase in microplastics and nanoplastics, respectively, in gut bacterial clusters, while fecal bacterial abundance dropped by 41.4–52.0%. This shift suggests gut blockage and reduced microbial export to feces, potentially slowing marine carbon cycle.

Metagenomic sequencing further showed decreased diversity in fecal microbiomes, with core taxa like Pseudophaeobacter declining by 18.7–20.5% and plastic-degrading genera (e.g., Psychrobacter) enriching.

Meanwhile, while short-term exposure did not majorly disrupt overall metabolic functions, indicating microbial functional redundancy, the functional contribution ratios of different microbial communities underwent notable, shifts, highlighting long-term risks. Professor Wen-Xiong Wang, corresponding author, noted, ” The loss of core taxa weakens community resilience. Prolonged stress may lead to functional vulnerability. ”

Copepods are essential to ocean carbon cycling, as their fecal pellets sink, transporting nutrients. By altering their microbiomes, MNPs could compromise this process. The findings highlights the need for a closer look at how plastic pollution disrupts invisible but vital marine interactions.