Nematode traits after separate and simultaneous exposure to Polycyclic Aromatic Hydrocarbons (anthracene, pyrene and benzo[a]pyrene) in closed and open microcosms

The majority of experimental studies carried out to date, regarding the effects of pollutants on meiofauna have been conducted by means of closed systems, and rarely using open ones. The current work explored the impact of three Polycyclic Aromatic Hydrocarbons (PAHs), anthracene, pyrene and benzo[a]pyrene, applied alone or combined, on meiobenthic nematodes using both systems. The results revealed that single PAHs impacted the nematofauna similarly in closed or open systems with a higher toxicity observed for benzo[a]pyrene. However, the closed microcosms contaminated with PAHs became organically enriched, resulting in more non-selective deposit feeders and omnivores-carnivores. Taxonomic and functional effects related to combinations of PAHs were close to those of individual treatments in closed systems, however, for open ones, the outcomes were different. The caudal morphology influenced the response of taxa during their avoidance/endurance of hydrocarbons in open systems where the effects of PAHs mixtures appeared not only additive but also synergetic. Based on the results of the study, the use of open systems is preferred to closed ones as the research outcomes were more accurate and representing better conditions prevailing in nature. [Display omitted] •Benzo[a]pyrene was more toxic for meiobenthic nematodes than anthracene and pyrene.•Combined PAHs treatments appeared not only additive but also synergetic.•Closed microcosms were less suitable than open ones to start experiments.