Toxicity of PAHs-enriched sediments on meiobenthic communities under ocean warming and CO₂-driven acidification scenarios

This study aimed to assess the interactive effects of CO₂-driven acidification, temperature rise, and PAHs toxicity on meiobenthic communities. Laboratory microcosms were established in a full factorial experimental design, manipulating temperature (25 °C and 27 °C), pH (8.1 and 7.6), and PAH contamination (acenaphthene + benzo(a)pyrene spiked sediments and negative control). Temperature rise and CO₂-driven acidification led to a decrease in the densities of Copepoda. The density of nematodes Pseudochromadora and Daptonema also decreased, while Sphaerotheristus and Sabatieria densities increased, particularly in the absence of CO₂-driven acidification. Ostracoda densities increased in the acidified scenario. PAH contamination resulted in decreased Daptonema densities but increased Turbellaria and certain Nematoda genera (e.g. Pseudochromadora). Overall, the results indicate that the changes of meiobenthic communities caused by CO₂ acidification, warming, and PAH contamination are shaped by the vulnerability and tolerance of each taxonomic group, alongside indirect effects observed in Nematoda assemblages.