Using multiple endpoints to assess the toxicity of cadmium and cobalt for chlorophycean Raphidocelis subcapitata

Author(s)

dos Reis, Larissa Luiza ^{[1, 2]} ; Goncalves Alho, Lays de Oliveira ^{[1, 2]} ; de Abreu, Cinthia Bruno ^{[1, 2]} ; Gama Mela, Maria da Graca ^[2]

Affiliation

^[1] Univ Fed Sao Carlos UFSCar, Postgrad Program Ecol & Nat Resources PPGERN, Rodovia Washington Luis, Km 235, BR-13565905 Sao Carlos, SP - Brazil

^[2] Univ Fed Sao Carlos UFSCar, Dept Hydrobiol, Rodovia Washington Luis, Km 235, BR-13565905 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY; v. 208, JAN 15 2021.
• Web of Science Citations: 3

Abstract

Metals may cause damage to the biota of contaminated environments. Moreover, using multiple endpoints in ecotoxicological studies is useful to better elucidate the mechanisms of toxicity of these compounds. Therefore, this study aimed to evaluate the effects of cadmium (Cd) and cobalt (Co) on growth, biochemical and photosynthetic parameters of the microalgae Raphidocelis subcapitata, through quantification of lipid classes composition, chlorophyll a (Chl a) content, maximum (Phi(M)) and effective (Phi'(M)) quantum yields and efficiency of the oxygen-evolving complex (OEC). Both metals affected the algal population growth, with an IC50-96h of 0.67 and 1.53 mu M of Cd and Co, respectively. Moreover, the metals led to an increase in the total lipid content and reduced efficiency of OEC and Phi(M). Cell density was the most sensitive endpoint to detect Cd toxicity after 96 h of treatment. Regarding Co, the photosynthetic parameters were the most affected and the total lipid content was the most sensitive endpoint as it was altered by the exposure to this metal in all concentrations. Cd led to increased contents of the lipid class wax esters (0.89 mu M) and phospholipids (PL at 0.89 and 1.11 mu M) and decreased values of triglycerides (at 0.22 mu M) and acetone-mobile polar lipids (AMPL at 0.44 and 1.11 mu M). The percentage of free fatty acids (FFA) and PL of microalgae exposed to Co increased, whereas AMPL decreased in all concentrations tested. We were able to detect differences between the toxicity mechanisms of each metal, especially how Co interferes in the microalgae at a biochemical level. Furthermore, to the best of our knowledge, this is the first study reporting Co effects in lipid classes of a freshwater Chlorophyceae. The damage caused by Cd and Co may reach higher trophic levels, causing potential damage to the aquatic communities as microalgae are primary producers and the base of the food chain. (AU)

• FAPESP's process: 16/00753-7 - Toxic effects of emerging microcontaminants on planktonic food webs
• Grantee: Maria da Graça Gama Melão
• Support Opportunities: Regular Research Grants
• 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