Effects of cadmium and cobalt mixtures on growth and photosynthesis of Raphidocelis subcapitata (Chlorophyceae)

Author(s)

dos Reis, Larissa Luiza ; Goncalves Alho, Lays de Oliveira ; de Abreu, Cinthia Bruno ; Gebara, Renan Castelhano ; Mansano, Adrislaine da Silva ; Gama Melao, Maria da Graca

• Document type: Journal article
• Source: AQUATIC TOXICOLOGY; v. 244, p. 8-pg., 2022-01-25.

Abstract

Metals occur simultaneously in the environment, and therefore it is important to know their toxicity and mechanism of action when associated with another metal. Furthermore, anthropogenic actions increase their concentrations in the environment where they can interact and undergo transformations that can even increase their toxicity. This study aimed to evaluate the effects of cadmium (Cd) and cobalt (Co), isolated and combined, on the microalgae Raphidocelis subcapitata. Regarding the toxicity of isolated metals, the IC50 96 h was 0.08 mg L-1 of Cd and 0.16 mg L-1 of Co. Cell density decreased at all concentrations of the Cd tested. The parameters related to cell size, cell complexity and mean cell chlorophyll a (Chl a) fluorescence were significantly affected by both metals. According to species sensitivity curves (SSD), the micmalgae R. subcapitata was the second most sensitive organism to Co exposure and the tenth concerning Cd. Metal mixture data were best fitted to the concentration addition (CA) model and dose-ratio dependence (DR) deviation, showing synergism at high concentrations of Co and low concentrations of Cd. Besides that, antagonism was observed at low concentrations of Co and high concentrations of Cd. Photosynthetic performance, assessed by maximum quantum yield (Phi(M)) and oxygen evolving complex (OEC), presented antagonism effects for both analyzed parameters. Thus, the mixture of Cd and Co showed synergistic and antagonistic interactions for the parameters analyzed in R. Subcapitata, indicating the importance of understanding the mechanisms of toxicity of metal mixtures in phytoplankton. (AU)

• FAPESP's process: 18/07988-5 - Bioprospecting, characterization and optimization of Brazilian microalgal strains for CO2 biofixation and bioproducts of commercial importance
• Grantee: Ana Teresa Lombardi
• Support Opportunities: Research Projects - Thematic Grants