Two tropical oligochaetes as potential standard test species: a case study evaluating single and combined copper and manganese toxicity

ABSTRACT

The lack of toxicity tests using indigenous species in risk assessments of tropical regions has often been discussed. Thus, this study evaluated two tropical oligochaete species (Allonais inaequalis and Dero furcatus) for potential use as test species. To this end, the toxic effects of copper and manganese, both isolated and mixed, were evaluated for both species via acute tests. The test protocol developed by the Organisation for Economic Co-operation and Development (OECD) for temperate sediment-dwelling benthic oligochaetes could be successfully applied for both test species. The 96-h LC₅₀ values (mean ± standard deviation) for D. furcatus were 31 ± 3 µg L⁻¹ and 18 ± 0.061 mg L⁻¹ for copper and manganese, respectively. The corresponding values for A. inaequalis were 26 ± 1 µg L⁻¹ and 28 ± 0.063 mg L⁻¹, respectively. Compared to the toxicity values for temperate arthropods, D. furcatus and A. inaequalis had comparable or greater sensitivity to the evaluated metals. The mixture toxicity tests indicated a dose ratio-dependent deviation of the concentration addition (CA) model, with antagonism occurring especially if the effects in the mixture were provoked by copper. Overall, these findings indicated that these taxa are sensitive candidates for use in tropical ecotoxicity testing. Future studies can elucidate the mechanisms of chemical mixture toxicity.

KEYWORDS:

• Ecotoxicology
• metals
• tropics
• mixture toxicity
• Annelida
• species sensitivity distribution

Disclosure statement

No potential conflict of interest was reported by the author(s).

Competing interests

The authors have no conflicts of interest to declare that are relevant to the content of this article.

Author contribution

Antonio J. G.N.: Conceptualisation, Methodology, Formal analysis, Investigation, Writing – original draft. Raquel A. M.: Methodology, Formal analysis, Writing – review & editing. Douglas P. A.: Investigation, Writing – review & editing. Júlio C. S. L.: Investigation, Writing – review & editing. Thandy J. S. P.: Writing – review & editing. Michiel A. D.: Methodology, Writing – review & editing. Odete R.: Conceptualisation; Writing – Review & Editing; Project administration; Funding acquisition.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Additional information

Funding

This work was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brazil (CAPES) – Finance Code 001. FAPESP (grant number 2017/24126-4 and 2022/14293-9) and by the Portuguese government (FCT) through the research unit UID/AMB/04085/2020 (CENSE).

Notes on contributors

Antonio José Gazonato Neto

Antonio José Gazonato Neto received a degree in biological sciences from the Federal University of São Carlos, a master's degree in ecology and natural resources (PPGERN) from the Federal University of São Carlos and a PhD in sciences also from PPGERN.

Raquel Aparecida Moreira

Raquel Aparecida Moreira reveived a degree in biological sciences from the Federal University of Ouro Preto, a master's degree in ecology and natural resources (PPGERN) from the Federal University of São Carlos and a PhD in sciences also from PPGERN.

Douglas de Pádua Andrade

Douglas de Pádua Andrade received a degree in biological sciences from the State University of Minas Gerais, a master's degree in environmental sciences from the Federal University of Alfenas and a PhD in sciences from PPGERN at the Federal University of São Carlos.

Júlio César dos Santos Lima

Júlio César dos Santos Lima received a degree in biological sciences from the Federal University of Lavras, a master's degree in environmental sciences from the Federal University of Alfenas and a PhD in environmental engineering sciences from the Postgraduate Program in Environmental Engineering Sciences from the São Carlos School of Engineering at the University of São Paulo.

Thandy Júnio da Silva Pinto

Thandy Júnio da Silva Pinto received a degree in environmental and health engineering from the Federal University of Rondônia Foundation, a master's and PhD in environmental engineering sciences from the Postgraduate Program in Environmental Engineering Sciences from the São Carlos School of Engineering at the University of São Paulo.

Michiel Adriaan Daam

Michiel Adriaan Daam received a master's degree in environmental sciences from Radboud University Nijmegen, RUN, Netherlands and a PhD in biology from the University of Aveiro.

Odete Rocha

Odete Rocha received a degree in biological sciences from the Federal University of São Carlos, a master's degree in ecology from the University of São Paulo and a PhD in zoology from the University of London.