Ecotoxicity of mercury to Folsomia candida and Proisotoma minuta (Collembola: Isotomidae) in tropical soils: Baseline for ecological risk assessment

Abstract

Mercury (Hg) is a highly toxic nonessential trace metal. Despite its natural occurrence in the Earth's Crust, its concentrations have been steadily increasing in the environment due to anthropogenic sources. Recent studies have showed great concern about soil fauna, once the potential adverse effects of mercury concentrations in the environment of these invertebrates are still poorly understood, especially when linked to forest soils and tropical biota. Different collembolan species can show distinct toxicity effects to the contaminants, impairing its developing lifelong and affecting its diversity and abundance in the environment. Laboratory studies were performed to evaluate the ecotoxicity of Hg(II) to collembolan species collected in Brazil, Proisotoma minuta (autochthonous) and Folsomia candida (allochthonous), as a tool to predict effects in ecological risk assessment of tropical regions. Behavioral, acute and chronic tests were carried under temperatures of 20°C and 24°C using two test soils, natural and artificial, spiked with increasing mercury concentrations. F. candida was more sensitive to mercury contamination than P. minuta, presenting the most restrictive values of EC50 and LC50. Reproduction was a considerably more sensitive endpoint than avoidance and mortality. The 28-day lower EC50 values were found in chronic tests for F. candida in natural soil to 24°C (3.32mgHgkg(-1)), while for P. minuta was in tropical artificial soil to 20°C (4.43mgHgkg(-1)). There were similarity for each collembolan species to respond at the Hg(II) effects when exposed at 20°C and 24°C. F. candida can be suitable as a bioindicator species to mercury ecotoxicity tests in tropical forest soils.

Comparison of mercury and methylmercury bioaccumulation in earthworms (<i>Bimastus parvus</i>) native to landfill-leachate-contaminated forest soil

“…Our results indicated that THg concentrations in the reference forest soil surface varied between 0.074 mg kg -1 dw and 0.103 mg kg -1 dw, with a mean value of 0.087 mg kg -1 dw. These were similar to measurements from forest soils in Switzerland, which varied between 0.07 mg kg -1 dw and 0.55 mg kg -1 dw (Rieder et al, 2011), and soils in Brazil, which varied between 0.02 mg kg -1 and 0.15 mg kg -1 (Buch et al, 2017(Buch et al, , 2016. The concentrations were lower than those from soils in French Guiana, which were between 0.25 mg kg -1 and 0.55 mg kg -1 (Da .…”

Commercial glyphosate-based herbicides effects on springtails (Collembola) differ from those of their respective active ingredients and vary with soil organic matter content

“…Initially, we wanted to assess nontarget effects using the Collembola species F. candida, which is a surrogate species for soil fauna in ecotoxicological studies (Ockleford et al 2017). However, we were surprised to find no individuals of this species in our pitfall traps, although others successfully used this sampling method with this species (Buch et al 2016). Instead, we collected many individuals of another Collembola species, Sminthurinus niger with our traps, and could therefore use this species for our assessment.…”

“…Each of the beforementioned studies has all been conducted under specific soil types and soil organic matter (SOM) levels. However, soil properties and Collembola activity (Potapov et al 2017;Rendoš et al 2016) and also absorption and half-life of pesticides are affected by SOM levels (Buch et al 2016;Silva et al 2019). To the best of our knowledge, no study experimentally tested interactive effects between GBH/ AIs and SOM levels.…”

Soil ecotoxicology in Latin America: Current research and perspectives

“…Buch et al using acclimated populations of F. candida and Proisotoma minuta that were originally collected in a forest area in Rio de Janeiro, Brazil, carried out ecotoxicity tests with soils spiked with mercury; F. candida was more sensitive to this contaminant than P. minuta , suggesting that the results for the standard test species could be used to protect natural populations of that species. Chelinho et al reported results of a soil microarthropod study in which the intrinsic sensitivity of the local collembolan community to carbofuran was rather similar to that for F. candida (European strain) using the same test soil.…”

“…The available data do not allow a consistent generalization to be made about the sensitivity among tested species, because it appears that toxicity is contaminant specific, species specific, and indeed soil specific . Therefore, additional research is needed to reduce uncertainties associated with the interactions of different ecologically relevant species in terms of both the type and nature of the contaminants and the type and nature of the soils before suitability of the native test species can be assessed.…”