Bioaccumulation and physiological effects of copepods sp. (Eucyclop sp.) fed Chlorella ellipsoides exposed to titanium dioxide (TiO2) nanoparticles and lead (Pb2+)

The demand for manufactured products and the derivatives of nanomaterials and non essential metals continue to increase, and as a consequence their presence in fisheries and aquaculture has therefore become a major concern for the risks to which our environment is exposed. The bioaccumulation profile of binary compounds (Titanium dioxide nanoparticles and lead) and their effects on the feeding behaviour of copepods were assessed in a simplified food chain including, the freshwater alga Chlorella ellipsoides and the cyclopoids copepods sp. Our results indicated that Pb and TiO2 NPs individually and mixed can be transferred from alga to copepods via dietary pathway. The highest bioconcentration factor (748.5) was recorded for Pb in the combined compounds (Pb15 + Ti16.5) μg L−1 and the highest BCF (5.57) recorded for TiO2 NPs was found in TiO2 NPs (16.5) alone. Ingestion and filtration rate decreased significantly (p < 0.05) in all treatments. Analysis of variance (ANOVA) showed that the combination of these metals significantly (p < 0.05) decreased ingestion and filtration rate. In addition, the individual compounds and their combinations significantly (p < 0.05) increased carbohydrate and total lipid content. The antioxidant activities showed significant (p < 0.05) effect of Glutathione peroxidase (GPx), Glutathione reductase (GR), catalase (CAT) however, SOD and MDA were not significant (p > 0.05) in both single and binary treatments. The results demonstrate that the co-exposure of TiO2 NPs and Pb inhibit the ingestion and filtration of microalgae by cyclopoid copepods sp. and also induce increase of carbohydrate, lipid; GPx, GR and CAT due to stress.