The microalgae Chaetoceros tenuissimus exposed to contaminants of emerging concern: A potential alternative to standardized species for marine quality assessment

Microalgae occupy a key trophic level since primary producers at the base of the aquatic food chain. Moreover, they are well suited for ecotoxicological tests because easily cultured and sensitive to contaminants. However, species sensitiveness to the same chemicals can vary greatly. Thus, we characterized the non-standardized diatom Chaetoceros tenuissimus by means of growth inhibition, biochemical, and infrared-spectroscopy (FT-IR) tests and compared the results against the standardized diatom Phaeodactylum tricornutum. The two species were exposed for 72 h to four chemicals: nanoparticles (n-TiO2, n-ZnO), potassium dichromate (K2Cr2O7), and surfactant (polyethylene glycol; PEG). The sensitivity of C. tenuissimus in the growth inhibition test and the chlorophyll-a analysis was always higher than P. tricornutum. In particular, the chlorophyll-a analysis exhibited an earlier endpoint for C. tenuissimus exposed to all chemicals here considered. FT-IR showed spectral alterations (molecular changes in chlorophyll) in both microalgal species exposed to the chemicals compared to the negative controls, with stronger alterations in C. tenuissimus than P. tricornutum. In conclusion, C. tenuissimus showed higher sensitivity to a broad range of toxic chemicals, indicating the potential use of this species in marine quality assessment as an alternative to the standardized P. tricornutum.