University of Wollongong
Browse

Chronic toxicity of an environmentally relevant and equitoxic ratio of five metals to two Antarctic marine microalgae shows complex mixture interactivity

Download (1.84 MB)
journal contribution
posted on 2024-11-15, 01:46 authored by Darren Koppel, Merrin Adams, Catherine K King, Dianne Jolley
Metal contaminants are rarely present in the environment individually, yet environmental quality guidelines are derived from single-metal toxicity data. Few metal mixture studies have investigated more than binary mixtures and many are at unrealistically high effect concentrations to freshwater organisms. This study investigates the toxicity of five metals (Cd, Cu, Ni, Pb, and Zn) to the Antarctic marine microalgae Phaeocystis antarctica and Cryothecomonas armigera. Two mixtures were tested: (i) an equitoxic mixture of contaminants present at their single-metal EC10 concentrations, and (ii) an environmental mixture based on the ratio metal concentrations in a contaminated Antarctic marine bay. Observed toxicity, as chronic population growth rate inhibition, was compared to Independent Action (IA) and Concentration Addition (CA) predictions parameterised to use EC10 values. This allowed for the inclusion of metals with low toxicities. The biomarkers chlorophyll a fluorescence, cell size and complexity, and intracellular lipid concentrations were assessed to investigate possible mechanisms behind metal-mixture interactions. Both microalgae had similar responses to the equitoxic mixture: non-interactive by IA and antagonistic by CA. Toxicity from the environmental mixture was antagonistic by IA to P. antarctica; however, to C. armigera it was concentration-dependent with antagonism at low toxicities and synergism at high toxicities by both IA and CA. Differences in dissolved organic carbon production and detoxification mechanisms may be responsible for these responses and warrants further investigation. This study shows that mixture toxicity interactions can be ratio, species, and concentration dependent. The responses of the microalgae to different mixture ratios highlight the need to assess toxicity at environmentally realistic metal ratios. Parameterising IA and CA reference models to use EC10s allowed for the inclusion of metals at low effect concentrations, which may otherwise be ignored. Reference mixture models are generally suitable for predicting chronic toxicity of metals to these marine microalgae at environmentally realistic ratios and concentrations.

History

Citation

Koppel, D. J., Adams, M. S., King, C. K. & Jolley, D. F. (2018). Chronic toxicity of an environmentally relevant and equitoxic ratio of five metals to two Antarctic marine microalgae shows complex mixture interactivity. Environmental Pollution, 242 (Part B), 1319-1330.

Journal title

Environmental Pollution

Volume

242

Pagination

1319-1330

Language

English

RIS ID

130126

Usage metrics

    Categories

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC