An approach to determining the nitrofurazone-induced toxic dynamics for ecotoxicity assessment using protozoan periphytons in marine ecosystems.

With several observable responses and sensitivity of protozoans to nitrofurazone (NFZ), the toxic effects of NFZ on protozoans can be an early warning signal of NFZ contamination in the aquatic environment. To evaluate the toxic dynamics induced by NFZ, protozoan samples were collected using microscopy glass slides and exposed to the five concentrations of NFZ: 0, 1, 2, 4, and 8 mg ml. Substantial differences in the species composition and toxic-dynamics patterns were observed among all concentrations. Briefly, periphytic euplotids and pleurostomatids were the most prevalent at each concentration level, while dysteriids were less dominant among all treatments. Multivariate analysis revealed significant (P < 0.05) differences in the taxonomic patterns of the test organisms among the five treatments. Furthermore, significant deviation of protozoan communities from the expected taxonomic breadth was observed to occur in a dose-dependent manner. Based on these findings, it is suggested that protozoan periphytons could be used as bioindicators to assess the ecotoxicity of NFZ in the marine environment.