Abstract-Nanomaterials are used in a wide spectrum of applications, including nanowires that are objects with at least one of its dimensions in the range of 1 to 100 nm. Recently, a new type of silver vanadate nanowire decorated with silver nanoparticles (SVSN-LQES1) with promising antimicrobial activity against different pathogenic bacteria was described. The objective of the present study was to evaluate the role of silver and vanadium release in the acute toxicity of this material using Daphnia similis. To verify the effect of the presence of the nanowires in the test solution, tests were performed before and after filtration. Total silver release to the testing media was determined using the method of inductively coupled plasma atomic emission spectroscopy (ICP-AES). Silver vanadate nanowires decorated with silver nanoparticles SVSN-LQES1 are acutely toxic to D. similis; the release of silver from the nanomaterial trapped in the gut along with the silver released to the test media seems to be responsible for the observed toxicity. Although toxic to Daphnia, vanadium does not contribute to the toxicity of SVSN-LQES1. The observed increase in lipid droplets appears to be related to the exposure of the organisms to the nanomaterials, but the significance of this response needs further investigation. Environ. Toxicol. Chem. 2013;32:908-912. # 2013 SETAC

There is a lack of suitable tropical marine species for ecotoxicity tests. An attractive model organism for ecotoxicology is the marine amphipod Parhyale hawaiensis, which is already a model for genetic and developmental studies. This species is widespread, can tolerate changes in salinity, is easy to handle and is representative of circumtropical regions. The aim of this work was to describe standardized procedures for laboratory husbandry, define conditions for acute toxicity tests, and to provide acute toxicity test results for some reference toxicants. Culturing conditions for the organism in the laboratory were established in reconstituted seawater (30 ± 2 salinity), 24 ± 2 °C, photoperiod 12/12 h light/dark. Acute toxicity test procedures were developed for 96 h-exposure time, and organisms at ages <7 days. The miniaturized version of the test, based on 96-well microplates and 200 µL of exposure media provided consistent results compared to larger exposure volumes (80-mL vials protocol). Acute toxicity of Ag, Cd, Cu, Zn and ammonia determined for P. hawaiensis were consistent to previous results for other marine amphipods. We conclude that P. hawaiensis can be successfully cultured in standardized conditions and be effectively used in acute toxicity testing. Further development and use of this model will enable standardized and reproducible ecotoxicology investigations in understudied and vulnerable tropical marine ecosystems.

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To assess the risk of chemical contaminants it is desirable to derive toxicity data from representative species of the ecosystem intended to be protected. However, species of occurrence in Brazil are rarely used in toxicity tests, especially for marine and estuarine environments. To address this need, we evaluated the toxicity of different toxicants such as metals and organic compounds to marine invertebrates of Brazilian occurrence, representative from tropical regions and cultivated in laboratory. We used two epibenthic test species of Brazilian occurrence, Parhyale hawaiensis, a deposit feeding amphipod and Nitocra sp, a harpacticoid copepod. Nitocra sp. was more sensitive than other copepods to zinc, and more sensitive than P. hawaiensis to disperse dyes. Sensitivity species distribution revealed that Nitocra sp. and P. hawaiensis were similarly responsive as other marine species to zinc, and Nitocra sp. was among of the most sensitive species. Moreover, our study highlighted that organic compounds are poorly explored in toxicity evaluation with marine organisms; therefore, more studies need to be carried out to assess the toxicity of different substances using marine and estuarine organisms representative of tropical ecosystems.

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