With the rapid increase in the synthesis and application of graphene oxide (GO), questions
have emerged about its inadvertent entry into aquatic habitats and the ecological
consequences associated with such exposure While several studies have addressed the
acute effects of GO, knowledge on its chronic impacts across multiple trophic levels
remains limited. In this study, we assessed the chronic toxicity of a well-characterized
GO product using model organisms representing three trophic levels: the bioluminescent
marine bacterium Aliivibrio fischeri, unicellular green algae (Chlamydomonas reinhardtii,
Chlorella vulgaris, Desmodesmus subspicatus), the cyanobacterium Synechococcus elongatus,
and the freshwater cladoceran Daphnia magna. Endpoints included bioluminescence inhibition
in bacteria, growth inhibition in photosynthetic primary producers, and reproduction
and refined physiological parameters (heart rate, feeding activity) in D. magna. Our
results demonstrated clear concentration-dependent chronic effects of GO, with A.
fischeri, the applied photosynthetic primary producers and D. magna exhibiting significant
inhibition of bioluminescence, growth, delayed onset of reproduction, and reduced
fitness parameters, respectively. Based on the collected data, a comprehensive ecotoxicological
risk assessment was carried out, revealing that pristine GO may pose negligible hazard
to aquatic ecosystems under environmentally relevant exposure scenarios. The outcomes
clearly demonstrate the relevance of incorporating chronic and multi-trophic effects
when evaluating the ecological risks of emerging nanomaterials such as GO.
