Toxicity of ZnO nanoparticles to the copepod Acartia tonsa, exposed through a phytoplankton diet

Abstract

Zinc oxide (ZnO) nanoparticles are being increasingly utilized in a variety of products and applications and are therefore commonly discharged into aquatic environments, increasing exposure and potentially impacting aquatic organisms. Zinc oxide nanoparticles can depress growth of some marine phytoplankton, and several examples of nanoparticle trophic transfer have been documented, although not within planktonic communities. The authors test whether feeding on ZnO-exposed phytoplankton could cause toxic effects in a widespread and ecologically important marine grazer, the copepod Acartia tonsa. The authors exposed the diatom Thalassiosira weissflogii to ZnO nanoparticles for 7 d and measured growth, zinc accumulation, and zinc distribution within the algal cells to elucidate bioavailability to grazing copepods. Thalassiosira weissflogii cultured with nano-ZnO were continuously fed to A. tonsa for 7 d, and reproduction and survival were quantified. A dose-dependent growth reduction was observed in T. weissflogii exposed to nano-ZnO, with a 20% effective concentration (EC20) of 70 µg/L Zn and a lowest observed effect concentration (LOEC) of 99 µg/L Zn. Zinc accumulation in the algae occurred dose-dependently over time, with the majority of the zinc partitioning into the cell wall fraction. Feeding on ZnO-exposed diatoms led to a decrease in copepod survival and reproduction. The EC20s corresponding to the dissolved zinc concentration in the T. weissflogii exposure media were 112 µg/L (13 µg/g dry wt) and 143 µg/L (16 µg/g dry wt), and the LOECs were 168 µg/L (17 µg/g dry wt) and 263 µg/L (21 µg/g dry wt) for copepod survival and reproduction, respectively. These results provide evidence of trophic transfer of metal contaminants associated with metal oxide nanomaterials within a marine plankton community, leading to a reduction in individual demographic performance of an important coastal marine grazer.

Ecotoxicity of Zinc Oxide Nanoparticles in the Marine Environment

“…However, an exposure of the copepod Acartia tonsa to ZnO-NP-dosed diatom T. weissflogii at the highest concentration of 263 mg L À1 Zn showed a significant reduction in survival and reproduction by 52 % and 50 %, respectively, after 7 days of exposure [29]. These authors confirmed the transfer of ZnO-NPs to A. tonsa from the dosed algae, illustrating their potential for trophic transfer [29].…”

“…Toxic effects of ZnO-NPs to these small crustacean species are associated with the primary particle size, the concentration of free zinc ions, and the aggregates of the ZnO-NPs. More importantly, some studies reported that toxic effects of ZnO-NPs may also be occurring at environmentally realistic concentrations [29,31].…”

Considerations of Environmentally Relevant Test Conditions for Improved Evaluation of Ecological Hazards of Engineered Nanomaterials

“…92, 93 Environmental factors are examined, including how ENMs interactively affect soil water availability 94 and soil bacterial communities. 95 Single-species experiments that assess ENM bio-association 96, 97 or bioaccumulation 71, 98 precede and motivate using microcosms for assessing dual species trophic transfer 98-101 and potential biomagnification. 102 …”

Toxicity of seaweed-synthesized silver nanoparticles against the filariasis vector Culex quinquefasciatus and its impact on predation efficiency of the cyclopoid crustacean Mesocyclops longisetus

“…To the best of our knowledge, few studies investigated the non-target effects of nanoparticles against predatory copepods (Oberdorster et al 2006;Jarvis et al 2013;Park et al 2014, see Fabrega et al 2011, and Baun et al 2008 for reviews), and no evidences are available about the toxicity of green-synthesized nanoparticles against these predaceous aquatic organisms. No efforts have been carried out to integrate classic biological control programs and nanobiotechnological tools for eco-friendly control of mosquito vectors.…”