Boric acid as a reference substance in avoidance behaviour tests with Porcellio dilatatus (Crustacea: Isopoda).

Isopods are macrodecomposers in terrestrial ecosystems, contributing to soil organic matter breakdown and nutrient cycling. They have been considered sensitive in laboratory tests designed to evaluate contaminants effects and are considered likely candidates to have a standardized protocol for ecotoxicity tests. For this purpose, a reference substance should be proposed as positive control in laboratory tests. This work aimed to evaluate the avoidance behaviour of the isopod species Porcellio dilatatus to boric acid (H3BO3; BA). Interlaboratory comparison tests were carried out based on the ISO guideline for earthworms, using tropical artificial soil as substrate, in the concentrations of 0, 125, 250, 500, 750, 1000, 1300 and 1800 mg BA kg-1 soil. Avoidance behaviour was evaluated in group (six organisms per replicate) and in individual tests (one organism per replicate), in dual-section plastic boxes, which received control soil (not contaminated) in one side and tested soil (with BA) in another one. The percentage of organisms in each side was recorded after 48 h, and data were analysed using Fisher exact test (p < 0.05) and t-test. Results showed significant avoidance response in individual tests at 250 mg kg-1 and in group tests at 500 mg kg-1. Limited habitat function (< 20% of organisms) for both tests and laboratories were observed at the highest tested concentration of 1800 mg kg-1, indicating the low sensitivity of this species to BA in avoidance tests, if compared to other substances in literature. Results showed that BA can be used as reference substance until a better option will be proposed.

Functional and structural parameters to assess the ecological status of a metal contaminated area in the tropics.

Ecological parameters (soil invertebrates, microbial activity, and plant community) were assessed in a metal contaminated site in an abandoned lead smelter and non-contaminated reference sites, as part of an ecological risk assessment (ERA). Vegetation cover inside the smelter area was lower and presented a more homogenous species composition than outside. A more simplified and less abundant vegetation community within the smelter area also simplified the habitat conditions, which in addition to metal toxicity, impaired the soil microbial and faunal communities. A significant reduction in the feeding activity was observed within the smelter area. Also a significant change in community composition of surface dwelling invertebrates was observed at those sites when compared to sites outside the smelter area. Moreover, basal respiration, microbial biomass C, dehydrogenase and phosphatase activity also decreased in several of these points under the smelter area. As a result, a significant impairment of organic material decomposition in the most contaminated sites was observed. Metal contamination affected the ecological status of the site, leading to a risk for ecosystem functioning and provisioning of ecosystem services like organic matter decomposition and nutrient cycling, even 17 years after the end of smelting activities. Regarding the sensitivity of the ecological parameters assessed, most were able to distinguish sites within the smelter area boundaries from those outside. However, only bait lamina (feeding activity), basal respiration and microbial biomass carbon presented high capacity to distinguish the level of soil contamination, since they were significantly correlated with metal loadings, and thus are promising candidates to be integrated in the Ecological Line of Evidence of an ERA.

Reproduction of Cubaris murina (Crustacea: Isopoda) under laboratory conditions and its use in ecotoxicity tests.

Reproduction of the isopod Cubaris murina was studied in the laboratory in order to observe the offspring number per brood, the number and duration of the incubation periods, and the influence of repeated mating on number of young per brood. An experiment was conducted with two different groups: female/male pairs and females that were isolated after mating. No significant difference was found between the two reproductive female groups for the mean number of young per brood (x = 25) and the duration of the incubation periods (x = 17 days). One mating was enough for at least five broods, with no reduction in brood size. There was no significant difference between the number of adult males and females. Low-density cultures had a significantly higher growth rate compared to high-density cultures. Furthermore, the experimental results for optimization isopod culture conditions for terrestrial ecotoxicity testing are reported.

Reproduction of Cubaris murina (Crustacea: Isopoda) under laboratory conditions and its use in ecotoxicity tests / Reprodução de Cubaris murina (Crustacea: Isopoda) em condições de laboratório e seu uso em testes de ecotoxicidade

Reproduction of the isopod Cubaris murina was studied in the laboratory in order to observe the offspring number per brood, the number and duration of the incubation periods, and the influence of repeated mating on number of young per brood. An experiment was conducted with two different groups: female/male pairs and females that were isolated after mating. No significant difference was found between the two reproductive female groups for the mean number of young per brood (x = 25) and the duration of the incubation periods (x = 17 days). One mating was enough for at least five broods, with no reduction in brood size. There was no significant difference between the number of adult males and females. Low-density cultures had a significantly higher growth rate compared to high-density cultures. Furthermore, the experimental results for optimization isopod culture conditions for terrestrial ecotoxicity testing are reported.

A reprodução do isópodo Cubaris murina foi investigada em laboratório para observar: o número de filhotes por ninhada, número e duração dos períodos de incubação, e se repetidas cópulas influenciam o número de juvenis por ninhada. Um experimento foi conduzido com dois diferentes grupos: pares com uma fêmea e um macho e fêmeas mantidas individualmente depois da cópula. Não foram encontradas diferenças estatisticamente significantes entre os dois grupos de fêmeas em relação ao número de filhotes por ninhada (x = 25) e a duração dos períodos de incubação (x = 17 dias). Uma cópula foi suficiente para ao menos cinco ninhadas, sem redução em seu tamanho. A proporção sexual dos adultos de C. murina em laboratório não apresentou diferenças significativas entre a proporção de machos e fêmeas nos cultivos. A densidade influencia o crescimento dos isópodos de forma significativa: culturas com baixa densidade têm maior taxa de crescimento do que culturas com alta densidade. Os resultados experimentais sobre a eficiência dos cultivos em laboratório para ensaios ecotoxicológicos terrestres são apresentados.