A robust bioassay to assess the toxicity of metals to the Antarctic marine microalga Phaeocystis antarctica

Enviro Toxic and Chemistry

Wasley

et al. 2019

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There are limited data on the sensitivity to contaminants of marine organisms in polar regions. Consequently, assessments of the risk of contaminants to marine biota in polar environments typically include extrapolations from temperate and/or tropical species. This is problematic because the taxonomic composition of organisms differs between polar and temperate/tropical waters, and both the toxicity of chemicals and the physiology of organisms are very different at the stable low temperatures experienced in polar marine systems. Collecting high‐quality sensitivity data for a wide range of marine polar organisms using traditional toxicity assessment approaches is a time‐consuming and difficult process, especially in remote and hostile environments. We applied a rapid toxicity testing approach, which allowed a much larger number of species to be tested than would be possible with traditional toxicity test methods, albeit with lower replications and fewer exposure concentrations. With this rapid approach, sensitivity estimates are less precise, but more numerous. This is important when constructing species sensitivity distributions (SSDs), which aim to represent the sensitivity of communities. We determined the approximate sensitivity (4‐ and 10‐d median lethal concentration [LC50] values) of a large and representative sample of Antarctic marine invertebrates to copper (Cu), zinc (Zn), and cadmium (Cd). Up to 88 LC50 values (from 88 different taxa) were used in the construction of SSDs. The hazardous concentrations for 1% of taxa (HC1) based on 10‐d LC50 values were 37, 346, and 792 μg/L for Cu, Zn, and Cd, respectively. Our results provide a basis for estimating the risk of exposure to metals for a large representative sample of marine polar invertebrates. Environ Toxicol Chem 2019;38:1560–1568. © 2019 SETAC

Section: Sensitivity Of Antarctic Invertebrates To Metalssupporting

confidence: 90%

Sensitivity of a Large and Representative Sample of Antarctic Marine Invertebrates to Metals

Kefford

Enviro Toxic and Chemistry

Wasley

et al. 2019

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“…Measurements of C DGT from aim 2 were used in independent action and concentration addition mixture models using the approach outlined in Koppel et al (2018), adapted from Hochmuth et al (2014). For concentration addition, toxic units were based on individual metal's EC10s, calculated by dividing the measured dissolved concentration of each metal in the mixture by its corresponding EC10 value calculated from single-metal treatments (Gissi et al 2015;Koppel et al 2017). The program R was used for all statistical analyses (R Development Core Team 2016) using the tidyverse package for graphing and data analysis (Wickham 2009 Buffle et al (2007Buffle et al ( , 2018 a Empirically determined diffusion coefficients from the present study are the mean and standard deviation of the 3 treatments.…”

Section: Dgt Performance In Cold Marine Watersmentioning

confidence: 99%

Diffusive Gradients in Thin Films Can Predict the Toxicity of Metal Mixtures to Two Microalgae: Validation for Environmental Monitoring in Antarctic Marine Conditions

Koppel

Adams

et al. 2019

Environ Toxicol Chem

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Anthropogenic contamination in the Antarctic near‐shore marine environment is a challenge for environmental managers because of its isolation, high costs associated with monitoring and remediation activities, and the current lack of Antarctic‐specific ecotoxicological data. The present study investigated the application of diffusive gradients in thin films (DGT) with a Chelex‐100 binding resin for metal contaminant assessment in Antarctic marine conditions. Diffusion coefficients for cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn), determined at 1 °C, ranged between 2.1 and 2.6×10–6 cm2/s and were up to 32% lower than those derived by theoretical calculations. Competition of metals on the DGT binding resin was observed at subsaturation concentrations, reducing the effective capacity for metal uptake by approximately 60%. The lability of the dissolved (0.45 µm filterable) Cd, Cu, Pb, and Zn metal fraction to DGT was generally >90% and unaffected by the presence of the Antarctic marine microalga Phaeocystis antarctica. Both DGT and dissolved metal concentrations gave equivalent mixture toxicity predictions in independent action and concentration addition models to P. antarctica and Cryothecomonas armigera; that is, predictions using DGT‐labile concentrations also showed antagonism to P. antarctica, which agrees with previously determined mixture interactivity. The benefits of DGT over traditional sampling techniques (i.e., discrete water sampling) include lower method detection limits (MDLs), in situ assessment, and time‐averaged concentrations which capture pulses of contamination typical of the Antarctic near‐shore marine environment. The present study provides MDLs and recommended minimum deployment times to guide field deployments in Antarctica. Environ Toxicol Chem 2019;38:1323–1333. © 2019 SETAC

“…These species are both important components as primary producers in Antarctic marine food webs, and have different sensitivities to single metal contaminants (Gissi et al, 2015;Koppel et al, 2017).…”

Section: Phaeocystis Antarctica (Phylum Haptophyta) Is a Common Marinmentioning

confidence: 99%

“…To better understand how contaminants affect the Antarctic marine ecosystem, recent research has developed toxicity test protocols for a range of Antarctic and subantarctic organisms (Duquesne and Liess, 2003;Gissi et al, 2015;Hill et al, 2009;Holan et al, 2016;King and Riddle, 2001; Lewis et al, 2016;Marcus Zamora et al, 2015;Runcie and Riddle, 2007;Sfiligoj et al, 2015). These studies have only investigated the toxic response of organisms to single contaminants, and do not assess interactive effects of mixtures, as would be found in the Antarctic marine environment.…”

Section: Introductionmentioning

confidence: 99%

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

Koppel

Adams

Environmental Pollution

et al. 2018

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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.