Acute toxicity of copper and chromium oxide nanoparticles to Daphnia similis

Copper oxide nanoparticles (CuO NPs) are employed in antifouling paints, and chromium oxide nanoparticles (Cr2O3 NPs) have been used as a green pigment. Their extensive use can contaminate aquatic ecosystems, and the toxicological effects of these NPs to the biota are poorly known. In this study, we evaluated the acute toxicity induced by CuO and Cr2O3 NPs, comparing with CuSO4 and Cr(NO3)3 as Cu2+ and Cr3+ ion source, respectively, using the microcrustacean Daphnia similis. The mean EC50-48h for CuO NPs was 0.064 mg L-1 and for CuSO4 was 0.015 mg L-1. CuO NPs tend to agglomerate, which may have reduced the release of Cu2+ in the test medium in relation to CuSO4.The mean EC50-48h for Cr2O3 NPs was 6.74 mg L-1 and for Cr(NO3)3 was 11.98 mg L-1. The reduced size of the Cr2O3 NPs (15-30 nm) and the higher zeta potential may have contributed to the higher stability in suspension and less potential for agglomeration, partially explaining the higher toxicity of NPs in relation to Cr(NO3)3. After the tests, we observed morphological damages such as increase in fat droplets, internal organ exposure and partially disintegration in organisms exposed to all tested substances, NPs or the salts

Are the functional diversity terms functional?:The hindrances of functional diversity understanding in the Brazilian scientific community

Interest in functional diversity has grown in recent years, indicating that knowledge on ecosystem functions gain importance. However, the incongruent use of terms may lead to misunderstandings and incomparable results. We aimed to review terms used in functional diversity among the Brazilian scientific community to identify if there is a lack of consensus in the terminology used. We applied online surveys to assess how these terms have been used by the Brazilian academics and searched for their definitions in the scientific literature. The definition of “ecological function” by Brazilian academics is like that of the niche, but we only found two articles defining such a term in the literature. Thus, it seems that “ecosystem function” is a more commonly used term outside of Brazil. The definition of “guilds” coincided with that used in the literature, although we still observed a lack of consensus in the latter. For “traits,” “functional group,” and “functional diversity” concepts, we found some discrepancy between the literature and questionnaires. These inconsistencies can be related to the use of different organizational levels for the definition of traits and to the practice of replacing species with functional groups in standard taxonomic diversity metrics, considering them as measurements of functional diversity. The adoption of cohesive terminology is crucial to ensure the comparability of scientific results in the scientific literature. However, finding a consensus in ecology represents a hard task; therefore, we encourage that, at least, researchers make clear which key concepts they adopted in their research to avoid misunderstandings