Comparative study of dissolved and nanoparticulate Ag effects on the life cycle of an estuarine meiobenthic copepod, Amphiascus tenuiremis

Abstract

Many nanotoxicological studies have assessed the acute toxicity of nanoparticles (NPs) at high exposure concentrations. There is a gap in understanding NP chronic environmental effects at lower exposure concentrations. This study reports life-cycle chronic toxicity of sublethal exposures of polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) relative to dissolved silver nitrate (AgNO) for the estuarine meiobenthic copepod, Amphiascus tenuiremis, over a range of environmentally relevant concentrations, i.e., 20, 30, 45, and 75 µg-Ag L. A concentration-dependent increase in mortality of larval nauplii and juvenile copepodites was observed. In both treatment types, significantly higher mortality was observed at 45 and 75 µg-Ag L than in controls. In AgNO exposures, fecundity declined sharply (1.8-7 fold) from 30 to 75 µg Ag L. In contrast, fecundity was not affected by PVP-AgNPs exposures. A Leslie matrix population-growth model predicted sharply 60-86% of decline in overall population sizes and individual life-stage numbers from 30-75 µg-Ag L as dissolved AgNO. In contrast, no population growth suppressions were predicted for any PVP-AgNPs exposures. Slower release of dissolved Ag from PVP-AgNPs and/or reduced Ag uptake in the nanoform may explain these sharp contrasts in copepod response.

Wastewater-Aged Silver Nanoparticles in Single and Combined Exposures with Titanium Dioxide Affect the Early Development of the Marine Copepod Tisbe battagliai

“…A developmental rate of 0.28 d –1 was determined in both natural seawater and SWW (10% SWW in natural seawater) controls, and this value was set to represent 100%. An increased toxicity was observed upon exposure to the positive AgNO 3 control, resulting in an EC 50 of 9.86 μg/L (Figure S2), which is in the same range as in previous studies with the copepod Amphiascus tenuiremis and confirms the increased sensitivity of the naupliar developmental stage. Exposure to increasing concentrations of Ag NPs led to delayed development at concentrations above 500 μg/L with a complete cessation of molting and increased mortality (Figure A).…”

“…Increased Ag toxicity to Daphnia magna has also been previously observed in the presence of TiO 2 with higher Ag body burdens that were explained by ingestion of Ag-sorbed TiO 2 NPs 40 . In the current study, the observed differences in toxicity are suggested to be due to the dynamic nature of the exposures, where organisms are being exposed to (i) a mixture of both particles and dissolved species released over time and (ii) different particulate complexes formed over time, which is in agreement with previous studies 39 . It should be noted that the NP behavior and subsequent exposure to T. battagliai may be altered by the presence of the algae.…”

“…40 In the current study, the observed differences in toxicity are suggested to be due to the dynamic nature of the exposures, where organisms are being exposed to (i) a mixture of both particles and dissolved species released over time and (ii) different particulate complexes formed over time, which is in agreement with previous studies. 39 It should be noted that the NP behavior and subsequent exposure to T. battagliai may be altered by the presence of the algae. NP agglomeration/interaction with released extracellular polymeric substances and deposition can alter the actual exposure, while NP/ion interaction with the algae surface during the exposures can also lead to a decrease in the dissolved species measured.…”

“…It should be noted that the NP behavior and subsequent exposure to T. battagliai may be altered by the presence of the algae. NP agglomeration/interaction with released extracellular polymeric substances and deposition can alter the actual exposure, while NP/ion interaction with the algae surface during the exposures can also lead to decrease in the dissolved species measured 39 . Moreover, the presence of food in the exposure system can lead to increased bioavailability due to Ag ions/NPs with the food source and increased uptake 41 .…”

Chronic effects of fire suppressors on the reproduction of the copepod Nitocra sp.

“…Benthic copepods are used in a range of studies, to evaluate how exposure to chemical stressors can be associated to effects on reproductive success, fecundity, and development of different species, such as the genus Nitocra spp. (Izar et al, 2019;Cariello, 2018;Perina, 2018), Tisbe biminiensis (Araújo-Castro, et al, 2009;Maciel, 2015;Régis, 2018), and Amphiascus tenuiremis (Sikder, 2018; Organisation for Economic Cooperation and Development, 2007). These detritivore filter feeding organisms constitute an important component of the marine trophic chain, linking the energy and biomass flow from the primary producers to the consumers, since they represent relevant dietary items for diverse marine organisms, such as fish (special fingerlings and post larvae) and other crustaceans (Ruppert et al, 1996).…”