Behavioural endpoints in earthworm ecotoxicology

Background, Aims and Scope  Endpoints in earthworm ecotoxicology scheduled in guidelines are mortality and reproduction rates. However, not only the direct influence of pollutants on population parameters but also changes in behaviour such as substrate avoidance can have an important impact on soil ecosystems. In practice two different avoidance response tests are applied in earthworm ecotoxicology: (i) a six-chamber test system and (ii) a two-chamber test system. Both avoidance response-test systems were compared to establish their respective advantages and disadvantages in order to advance the standardisation of behavioural tests. The earthworm avoidance-response tests were applied in addition to the standard acute and chronic earthworm toxicity tests (ISO 11268) in order to compare the sensitivity of the test endpoints. Methods  Test substrates were contaminated with crude oil and 2,4,6-Trinitrotoluene (TNT), respectively. The test species wasEisenia fetida. The earthworms were exposed to the contaminated substrates and their mortality (14 d), reproduction rates (number of cocoons after 28 d, juvenile hatching after 56 d), and substrate preference (48 h) determined. Results and Discussion  Whereas 1000 mg/kg TPH (Total Petroleum Hydrocarbons) did not show any lethal effects, 100% mortality occurred in soil with comparable TNT concentration. The acute tests consistently produced the highest effect concentrations whereas reproduction and substrate avoidance were the more sensitive test parameters. Both behavioural test systems, when compared, showed similar substrate avoidance after an incubation time of 48 h. The six-chamber test system provides the potential to test six different substrates/concentrations at one time. It was observed, however, that earthworms did not migrate among all test chambers within a test unit in order to select the most appropriate substrate. Orientation was observed only between directly neighbouring test compartments, which complicates the interpretation of the test results. Conclusion  Substrate avoidance and reproduction variables were clearly more sensitive test endpoints than mortality. Therefore avoidance-response tests proved to be useful test methods in detecting effects of sublethal concentrations of pollutants on earthworms. The test duration of the avoidance tests is much shorter compared to the standard acute and chronic earthworm toxicity tests, which makes them a quick screening tool for identifying potential soil toxicity. Both avoidance-response test systems showed comparable results regarding the test sensitivity. Nonetheless, the incomplete substrate use in the six-chamber avoidance test due to the reduced migration possibilities (orientation only to neighbouring chambers) might reduce the distinctness of test results as it allows only reliable information on the most avoided and therefore most toxic substrate but not on 1 a clear dose-response pattern. Thus, to gain valid results, the number of replicates and the arrangement of the different substrates must be adopted. The two-chamber test system is less time-consuming due to easy handling and test results can be quantified more easily. Recommendations and Outlook  In consequence of the better validity of test results, lower expenses for test containers and less time for handling, the use of the two-chamber system is preferred over the six-chamber test system to assess the toxicity of polluted soil. Because of the ecosystem consequences of behavioural effects and the fact that avoidance response tests can reveal the toxic potential of pollutants in low concentrations, such tests should be included into ecotoxicological test protocols.     

Comparison of the effects of zinc nitrate-tetrahydrate and tributyltin-oxide on the reproduction and avoidance behavior of the earthworm Eisenia andrei in laboratory tests using nine soils

The aim of this contribution was to evaluate whether the sensitivity of the earthworm avoidance test is comparable to that of the earthworm reproduction test (standard test guidelines for both are available). The objective was to determine if relatively simple short-term tests are useful as an initial screening step for the environmental risk assessment (ERA) of potentially contaminated soils prior to performing long-term, elaborate tests. Therefore, the effects of two model substances, zinc nitrate-tetrahydrate and tributyltin-oxide (TBT-O) on the reproduction and the avoidance behavior of the earthworm Eisenia andrei were compared using Organization for Economic Co-operation and Development (OECD) artificial soil as well as eight natural soils, including LUFA St. 2.2 soil, covering a wide range of pH-values, organic matter content and texture. Almost all tests fulfilled the validity criteria defined in the two standard guidelines published by the International Organization for Standardization (ISO), despite the fact that the properties of natural soils differed clearly from those of OECD artificial soil. The median effective concentration (EC50) values estimated for zinc nitrate-tetrahydrate in 48-h avoidance tests and in 56-day reproduction tests were often similar when using the same soil (seven out of nine soils). However, in the case of TBT-O, the outcome was more complex: in two test soils the avoidance EC50 values were by a factor >3 higher than the reproduction EC50 values. In one of the test soils it was the other way around and the remaining soils showed comparable EC50 values in both tests. Summarizing the results obtained here and according to experiences reported in the available literature, the earthworm avoidance test may be recommended as an initial screening tool in the ERA of potentially contaminated soils. However, further research is needed to understand the factors that contribute to the difference in sensitivity between reproduction and avoidance tests.     

Toxicity of three pesticides commonly used in Brazil to Pontoscolex corethrurus (Müller, 1857) and Eisenia andrei (Bouché, 1972)

The indiscriminate and excessive use of pesticides poses serious risks to humans and the environment, including soil biota. Ecotoxicological tests are useful to indicate the extent to which these chemicals are harmful and how and where their effects occur. Some of these tests were standardized by ISO (International Organization for Standartization) using the earthworm species Eisenia fetida and Eisenia andrei, both native to temperate climates. However, these species may be of lower relevance for soil ecotoxicological studies since they live in the litter and feed on fresh organic matter. The species Pontoscolex corethrurus, native to tropical regions, may be an alternative for more relevant ecotoxicological tests as it is an endogeic geophagous species. However, little is known of its sensitivity to pesticides. Therefore, avoidance and mortality tests were performed using E. andrei and P. corethrurus and three pesticides commonly used in Brazilian agriculture: carbendazim, carbofuran and glyphosate. The tests were conducted in tropical artificial soil (TAS). For carbendazim, the median avoidance concentration (AC₅₀) was 76.1 and 65.8 mg a.i. kg⁻¹ and the median lethal concentration (LC₅₀) 19.7 and 15.3 mg a.i. kg⁻¹ for E. andrei and P. corethrurus, respectively. For carbofuran, the AC₅₀ was 9.7 and 7.3 mg a.i. kg⁻¹ and LC₅₀ 13.5 and 9.3 mg a.i. kg⁻¹ for E. andrei and P. corethrurus, respectively. Concentrations applied in the field of these two pesticides have toxic effects on both species. Glyphosate showed no toxic effects for either species even at the highest concentration tested (47 mg a.i. kg⁻¹), although they displayed avoidance behavior at this concentration. The sensitivity of P. corethrurus appears to be similar to the standard species for the pesticides evaluated reinforcing the notion that E. andrei is a good test species. Nevertheless, further studies should be undertaken using other contaminants to confirm the similar sensitivity of both species and the relevance of E. andrei in ecotoxicological tests.     

Tolerance of genetically characterized <Emphasis Type="Italic">Folsomia candida</Emphasis> strains to phenmedipham exposure

Background, Aims, and Scope  The springtail Folsomia candida is a commonly used model species in ecotoxicological soil testing. The species reproduces parthenogenetically and, thus, laboratories use different clonal lineages. In this study, we investigated if genetic divergence between F. candida strains impacts the reaction to chemical stress and may thus affect the outcome of toxicity tests. Methods  In two exposure assays (life-cycle reproduction test and avoidance behaviour test), three laboratory strains of F. candida from Portugal (PTG), Spain (SPN) and Denmark (DNK) were exposed to different concentrations of the reference chemical phenmedipham. Genetic divergence among strains was estimated based on mitochondrial COI sequence data. Results  No significant differences between tolerance towards phenmedipham exposure were observed in a reproduction test. In contrast, one strain (SPN) showed a decreased susceptibility to phenmedipham compared to the other strains (PTG and DNK) in the avoidance assay. Discussion  A phylogenetic tree based on mitochondrial COI sequences revealed clear genetic differentiation between both ‘reaction types’. Thus, we found a potential lineage dependent stress reaction in avoidance behaviour towards the pesticide. Conclusions  Our findings have implications for the comparability of test results among laboratories. Reproduction tests seem to be more robust towards interclonal genetic differentiation than avoidance tests. Recommendations and Perspectives  We recommend the use of molecular tools for simple and cost effective genetic characterization of F. candida strains used in chemical avoidance tests. Closer investigations concerning the relation between genetic relatedness and chemical response will provide a more detailed and comprehensive picture on the role of intraspecific genetic differentiation in stress tolerance. ESS-Submission Editor: Prof. Dr. Henner Hollert (henner.hollert@bio5.rwth-aachen.de)     

Avoidance test with<Emphasis Type="Italic">Eisenia fetida</Emphasis> as indicator for the habitat function of soils: Results of a laboratory comparison test

Intention, Goal, Scope, Background. The habitat function of soils is often assessed using the reproduction test withEisenia fetida. As this test is rather labour-intensive, an alternative is needed which is less cost-intensive in terms of duration and workload, but gives reasonable results. The avoidance test withE. fetida is a suitable screening test meeting these criteria. However, before a novel test system can be generally recommended it has to be ensured that comparable results are acquired from different laboratories on the basis of the respective test guideline.

Objective

The avoidance test withE. fetida was performed as laboratory comparison test. The results were compared with those of the earthworm acute and reproduction tests carried out with the same soils.

Methods

The three tests were performed by three laboratories using eight contaminated soils and three control soils. The contaminated soils were mixed with the control soils to obtain different concentrations of the contamination.

Results and Discussion

The results of the avoidance test show that despite the partially considerable standard deviations a 72% agreement in the assessment of soils was reached with a toxicity criterion of >80% avoidance response. The sensitivity is at least that for the reproduction test and considerably surmounts the sensitivity of the acute test.

Recommendation and Outlook

The avoidance test is considered to be a suitable screening test for assessing the habitat function of soils. The whole test design could be improved by reducing the standard deviations among parallel test batches. With regard to standardization it is recommended to use control soils which have the same properties as the soils described in respective guidelines (e.g. ISO 11269-2, OECD 216, 217).

     

Earthworm avoidance test for soil assessments

For ecotoxicological assessments of contaminated or remediated soils pointing to the habitat function of soils for biocenoses, standardized tests with earthworms (acute test, reproduction test) are available among others. Tests used for routine applications should be sensitive and indicate impacts on test organisms after short test periods. The usually applied earthworm tests do not satisfactorily fulfil these criteria. Therefore, in the present work, a behavioural test with earthworms (test criterion: avoidance) was investigated in detail using uncontaminated, artificially contaminated and originally contaminated soils. It was demonstrated that the avoidance behaviour is primarily determined by pollutants, and not by chemical-physical soil properties. The sensitivity of the presented test reaches the sensitivity of established tests. For waste sites, a considerably higher sensitivity was determined. An avoidance behaviour of at least 80% of the worms leaving the soil to be assessed is proposed as a criterion for toxicity.     

Collembola in ecotoxicology—Any news or just boring routine?

Despite the uncontested significance of soils for human nutrition and drinking water quality, the majority of ecotoxicological testing is confined to aquatic test systems. Among the standardised tests for soils, the reproduction test with the springtail Folsomia candida is among the most widely used ones. First steps towards its standardisation were undertaken in the late 1980s. Here we review major advances that have been made since then, with respect to mechanistic, pragmatic and ecological aspects. Specifically we address the ecological relevance of any modifications of the standardised tests. We introduce a miniaturised version of the reproduction test which allows reducing the amount of soil per test unit to one third and the number of synchronised individuals to 40% as compared to the standard test. In addition, we developed an assay using Collembola eggs instead of synchronised adults. First results of a three-species test indicate that the presence of other species may affect choice behaviour. We point out a potential biased view of existing ecotoxicological data with Collembola due to the fact that most results refer to metal contamination. Finally, recommendations for future research are given, with special reference to avoidance and microcosm tests involving Collembola.     

The use of sewage sludge as soil amendment. The need for an ecotoxicological evaluation

Background, aim, and scope  Sewage sludge use in agriculture should be limited by the presence of metals and other persistent environmental pollutants. The present study aims to contribute for the definition of a test battery of ecotoxicological assays that allows a proper ecotoxicological characterization of sludges, providing information on their potential hazard and identified “safe” application levels. Materials and methods  Three sludges from distinct sources (urban, olive-processing, and electroplating industries) were tested using avoidance and reproduction tests with earthworms (Eisenia andrei) and springtails (Folsomia candida) and plant growth tests with turnips (Brassica rapa) and oats (Avena sativa). Different soil–sludge mixture concentrations mimicking recommended/realistic field dosages were tested. Results  Only the sludge from the electroplating industry induced an avoidance response from the earthworms (EC₅₀ = 0.4 t/ha) and collembolans (no observed effect concentration (NOEC) = 15 t/ha). This sludge was the only sludge responsible for any effect on the reproductive output of the earthworms (EC₅₀ = 7.74 t/ha). Regarding collembolans, none of the sludges tested caused any significant decrease in reproduction. In higher plant tests, the two industrial sludges were toxic, causing a decrease growth in both species. The EC₂₀ values determined for B. rapa were 20.3 and 24.2 t/ha and for A. sativa 14.7 and 16.2 t/ha for sludges from olive-processing and electroplating industries, respectively. Discussion  The metal loadings of the different test sludges could partially explain the results obtained. The toxicity of the test sludge from electroplating industry observed on the tested invertebrates and plants could be explained by the high amount of total chromium from which 22.3% was in the most toxic oxidation state—Cr(VI). However, the toxicity caused by the sludge from the olive-processing industry in the test plants could be attributed to the presence of other compounds (not measured in this study) since the metal content was not high enough to induce such an effect. The absence of toxicity showed by the urban test sludge was in agreement with its low levels of metals. Conclusions  The response of the different test organisms and end points varied according to the sludge type. The urban sludge was non-toxic whereas the sludge from the electroplating industry caused a toxic effect on almost all parameters measured (avoidance behavior of both test organisms, reproduction of earthworms, and growth of both plant species). Sludge from the olive-processing industry only caused a toxic effect on growth of both plant species. By analyzing the sensitivity of the different parameters for the most toxic sludge, it was found that avoidance and reproduction were more sensitive than plant growth, whereas plant seed germination was not sensitive at all. Recommendations and perspectives  The ecotoxicological evaluation of wastes can be used as an environmental safety control of sludge use in agriculture. A tiered approach could be adopted for this purpose, incorporating avoidance tests in the first tier (screening level) and reproduction and plant growth tests in a second tier. But more evidence aiming to define the most suitable ecotoxicological test battery for specific sludges with a different contamination profile is still needed.     

Applying a GLM-based approach to model the influence of soil properties on the toxicity of phenmedipham to Folsomia candida

Purpose

Soil properties are the main explanation to the different toxicities obtained in different soils due to their influence on chemical bioavailability and the test species performance itself. However, most prediction studies are centred on a few soil properties influencing bioavailability, while their direct effects on test species performance are usually neglected. In our study, we develop prediction models for the toxicity values obtained in a set of soils taking into account both the chemical concentration and their soil properties.

Materials and methods

The effects on the avoidance behaviour and on reproduction of the herbicide phenmedipham to the collembolan Folsomia candida is assessed in 12 natural soils and the Organisation for Economic Co-operation and Development (OECD) artificial soil. The toxicity outcomes in different soils are compared and explanatory models are constructed by generalised linear models (GLMs) using phenmedipham concentrations and soil properties.

Results and discussion

At identical phenmedipham concentrations, the effects on reproduction and the avoidance response observed in OECD soil were similar to those observed in natural soils, while effects on survival were clearly lower in this soil. The organic matter and silt content explained differences in the avoidance behaviour in different soils; for reproduction, there was a more complex pattern involving several soil properties.

Conclusions

Our results highlight the need for approaches taking into account all the soil properties as a whole, as a necessary step to improve the prediction of the toxicity of particular chemicals to any particular soil.     

Toxicity of phenmedipham and carbendazim to Enchytraeus crypticus and Eisenia andrei (Oligochaeta) in Mediterranean soils

Purpose

The main objective of the present study was to evaluate the toxicity of two reference chemicals, Carbendazim and Phenmedipham, for the compostworm Eisenia andrei (effects of Carbendazim) and the potworm Enchytraeus crypticus (effects of Phenmedipham) in 12 Mediterranean soils with contrasting soil properties. The observed toxicity was also compared to that obtained for OECD standard soil, used as a control.

Materials and methods

The soils were selected to be representative for the Mediterranean region and to cover a broad range of soil properties. The evaluated endpoints were avoidance behavior and reproduction. Soils were also assembled in two groups according to their pedological properties.

Results and discussion

Toxicity benchmarks (AC50s) obtained for E. andrei avoidance behavior in carbendazim-contaminated soils were generally higher for sandy soils with low pH. The toxic effects on the reproduction of the compostworms were similar in the six tested soils, indicating a low influence of soil properties. The avoidance response of E. crypticus towards Phenmedipham was generally highly variable in all tested soils. Even though, a higher toxicity was observed for more acidic soils. The EC50s for reproduction of the latter species varied by a factor of 9 and Phenmedipham toxicity also tended to be increasing in soils with lower pH, except for the soils with extreme organic matter content (0.6 and 5.8%).

Conclusions

A soil effect on chemical toxicity was clearly confirmed, highlighting the influence that test soils can have in site-specific ecological risk assessment. Despite some relationships between soil properties and toxicity were outlined, a clear and statistically significant prediction of chemical toxicity could not be established. The range of soil properties was probably narrow to give clearer and more consistent insights on their influence. For the four groups of tests, the toxicity observed for OECD soil was either similar, lower, or generally higher if compared with Mediterranean soils. Moreover, it did represent neither the organic matter content found in Mediterranean soils nor their textural classes.     

Sensitivity to cadmium of the standard test species Folsomia candida compared to two other species, Onychiurus yodai and Sinella umesaoi (Collembola)

Knowing whether test species used for single-species toxicity tests are representative of other species provides valuable information because contaminant effects are often extrapolated to the community level based on these tests. To evaluate how representative the sensitivity of the standard test collembolan species Folsomia candida is for Collembola, we devised toxicity tests using the collembolan species Onychiurus yodai and Sinella umesaoi, which exhibit life-forms different from F. candida. Sensitivity to cadmium (Cd) was compared between F. candida and the novel test species. The 50% effective concentrations for reproduction were 154.7, 72.2 and 40.9 mg Cd/kg dry soil for O. yodai, F. candida and S. umesaoi, respectively. Thus, the reproductive sensitivity of F. candida to Cd was between that of the other two species. Increasing reproductive sensitivity to Cd corresponded to increasing activity levels and a more surface-dwelling life-form. Our data may facilitate the generalisation of effect data for F. candida to other species.     

Ecotoxicological assessment of the effects of glyphosate and chlorpyrifos in an Argentine soya field

Background, Aim and Scope

Continuous application of pesticides may pollute soils and affect non-target organisms. Soil is a complex ecosystem; its components can modulate the effects of pesticides. Therefore, it is recommended to evaluate the potential environmental risk of these compounds in local conditions. We performed an integrated field-laboratory study on an Argentine soya field sprayed with glyphosate and chlorpyrifos under controlled conditions. Our aim was to compare the sensitivity of a series of endpoints for the assessment of adverse effects of the extensive use of these agrochemicals.

Materials and Methods

A RR soya field in a traditional farming area of Argentina was sprayed with glyphosate (GLY) or chlorpyrifos (CPF) formulations at the commercially recommended rates, according to a randomized complete block design with 3 replicates. In laboratory assays, Eisenia fetida andrei were exposed to soil samples (0–10 cm depth) collected between the rows of soya. Endpoints linked to behavior and biological activity (reproduction, avoidance behavior and bait-lamina tests) and cellular/subcellular assays (Neutral Red Retention Time — NRRT; DNA damage — Comet assay) were tested. Field assays included litterbag and bait-lamina tests. Physico/chemical analyses were performed on soil samples.

Results

GLY reduced cocoon viability, decreasing the number of juveniles. Moreover, earthworms avoided soils treated with GLY. No effects on either reproduction or on avoidance were observed at the very low CPF concentration measured in the soils sampled 10 days after treatment. Both pesticides caused a reduction in the feeding activity under laboratory and field conditions. NRRT was responsive to formulations of CPF and GLY. Comet assay showed significantly increased DNA damage in earthworms exposed to CPF treated soils. No significant differences in DNA migration were observed with GLY treated soils. Litterbag field assay showed no differences between treated and control plots.

Discussion

The ecotoxicological effects of pesticides can be assessed by monitoring the status of communities in real ecosystems or through the use of laboratory toxicity tests. Litterbag field test showed no influence of the treatments on the organic matter breakdown, suggesting a scarce contribution of soil macrofauna. The bait-lamina test, however, seemed to be useful for detecting the effects of GLY and CPF treatments on the activity of the soil fauna. CPF failed to give significant differences with the controls in the reproduction test and the results were not conclusive in the avoidance test. Although the field population density of earthworms could be affected by multiple factors, the effects observed on the reproduction and avoidance tests caused by GLY could contribute to its decrease, with the subsequent loss of their beneficial functions. Biomarkers measuring effects on suborganism level could be useful to predict adverse effects on soil organisms and populations. Among them, NRRT, a lysosomal destabilization biomarker, resulted in demonstrating more sensitivity than the reproduction and avoidance tests. The Comet assay was responsive only to CPF. Since DNA damage can have severe consequences on populations, it could be regarded as an important indicator to be used in the assessment of soil health.

Conclusions

Reproduction and avoidance tests were sensitive indicators of GLY exposure, with the former being more labor intensive. Bait-lamina test was sensitive to both CPF and GLY. NRRT and Comet assays revealed alterations at a subcellular level, and could be considered complementary to the biological activity tests. Because of their simplicity, some of these bioassays seemed to be appropriate pre-screening tests, prior to more extensive and invasive testing.

Recommendations and Perspectives

This study showed deleterious effects of GLY and CPF formulations when applied at the nominal concentrations recommended for soya crops. Further validation is needed before these endpoints could be used as field monitoring tools in Argentine soya soils (ecotoxicological risk assessment — ERA tools).

     

What causes variability in the Folsomia candida reproduction test?

Large variability is often observed in results of the Folsomia candida reproduction test [ISO 11267, Soil quality—inhibition of reproduction of Collembola (Folsomia candida) by soil pollutants. Inter. Stand. Org. Ed. Genève. (1998) 1–16] and can be detrimental to the test sensitivity. So, we investigated the effects of certain parameters (small differences of ambient temperature and age of the animals) on the variability of reproduction of F. candida. We show that a 1 °C difference has no perceptible effect but that a 1 day difference in age has. Studying the reproduction of isolated individuals shows that a strong apparent interindividual variability exists. Lastly, we compared the variability of reproduction in two tests differing from one another in duration; variability was clearly decreased by lengthening the test.     

Tiber River Quality in the Stretch of a Sewage Treatment Plant: Effects of River Water or Disinfectants to Daphnia and Structure of Benthic Macroinvertebrates Community

The evaluation of Tiber River quality, in a stretch including a sewage treatment plant, has been carried out by the contemporary evaluation of water effect on Daphnia and benthic macroinvertebrates community structure. To achieve a good status of a river water by the end of 2015, as provided in the Water Framework Directive (WFD) 2000/60/EC, is necessary to know the quality starting point. To this end, several endpoints are expected by the WFD, including Daphnia toxicity test and macroinvertebrate community analysis. River water sampling was conducted in the four seasons, from upstream to downstream a sewage treatment plant. I endpoint. At the outfall of the sewage treatment plant, river water showed very high acute toxicity to Daphnia only in summer; some toxic effect can be found also upstream in spring. Results at the outfall were consistent with the hypothesis that disinfectants, mainly used in summer to treat discharging waters, are responsible of river water acute toxicity: Daphnia tests with each disinfectant (NaClO, PAA, ClO₂) showed high toxicity. River waters were also utilized in Daphnia reproduction tests. Samples at the outfall (excluding the summer one, undoubtedly toxic) caused slight reduction in survival and fecundity. Disinfectants were also checked in reproduction tests. Still at NOEC_24h, they caused a significant toxicity on both death rate and reproduction. II endpoint. Macroinvertebrate benthic community composition was evaluated upstream and downstream the sewage treatment plant, on these data Extended Biotic Index (EBI), was determined to get a score as quality class. A reduction of water quality score was found downstream the plant, one season delayed (autumn) respect the acute test on Daphnia. Effect of disinfectant discharge, river dilution capability on a short spatial scale and use of different endpoints are discussed in term of river stretch quality.     

Stress protein response (Hsp70) and avoidance behaviour in Eisenia fetida, Aporrectodea caliginosa and Lumbricus terrestris when exposed to imidacloprid

Purpose  

The earthworm species Eisenia fetida and Eisenia andrei are commonly used in ecotoxicological standard tests. In the present study, we compared the sensitivity of E. fetida with that of two soil-dwelling earthworm species (Aporrectodea caliginosa and Lumbricus terrestris) in order to evaluate the capacity of E. fetida to predict effects of the insecticide imidacloprid. Responses were compared using two endpoints, a biochemical (changes in heat shock protein level (hsp70)) and a behavioural (avoidance behaviour).     

Effects of Cd and Pb on the survival and juvenile production of Sinella coeca and Folsomia candida

Degradation factors can cause both quantitative and qualitative changes in fauna and thus affect soil functioning. The use of bio-indicators may help to detect environmental changes. The aim of this study was to evaluate the effects of lead and cadmium on the biology (mortality, reproduction, egg hatching) of two euedaphic collembolans, Sinella coeca and Folsomia candida and to evaluate sensitivity differences between the two species. The results showed that low concentrations of lead did not cause dramatic effects on the survival and reproduction of both species. Reproduction of both species was reduced when the soil contained a nominal concentration of Pb at 1000 μg g^–1. S. coeca and F. candida showed a high sensitivity to cadmium and both their reproduction and survival were significantly reduced on exposure to 50 μg g^–1. Moreover, egg hatching of F. candida was affected by the cadmium concentrations in the soil, and by the amount of time that the eggs stayed in contact with cadmium. This study showed that the inhibition determined by Cd on F. candida juvenile production was caused in part by inhibition of deposition and, in part, by reduction of egg viability.     

Earthworm avoidance of biochar can be mitigated by wetting

Biochar has a great potential for enhancing soil fertility and carbon sequestration while enabling beneficial waste disposition. Because of the potential for widespread application, it is essential to proactively assess and mitigate any unintended consequences associated with soil biochar amendment. We conducted soil avoidance tests, growth and reproduction tests, and oxidative stress assays with the earthworm Eisenia foetida to assess the potential toxicity of soil amended with biochar produced from apple wood chips. Earthworms avoided soils containing 100 and 200 g/kg dry biochar at statistically significant levels (p < 0.05), and after 28-day incubation, these earthworms lost more weight than those in control (unamended) soil. However, biochar did not affect the reproduction of earthworms. We investigated whether the observed avoidance was due to nutrition deficiency, desiccation, or the presence of toxic polynuclear aromatic hydrocarbons (PAHs) formed during biochar production by pyrolysis. Nutrition deficiency was excluded by the lack of earthworm avoidance to soil amended with nutrient-deficient sand instead of biochar. Although traces of PAH were detected in the tested biochar (e.g., 25.9 μg/kg fluorene, 3290 μg/kg naphthalene, and 102 μg/kg phenanthrene), the lack of lipid peroxidation and no increase in superoxide dismutase activity in biochar-exposed earthworms suggests that presence of toxic compounds was not a likely reason for avoidance. Furthermore, wetting the biochar to its field capacity resulted in statistically undetectable avoidance relative to control soil, indicating that insufficient moisture could be a key factor affecting earthworm behavior in soil amended with dry biochar. To avoid desiccation of invertebrates and enable their beneficial ecosystem services, we recommend wetting biochar either before or immediately after soil application.     

Plasmodium blood parasite found in endangered Galapagos penguins (Spheniscus mendiculus)

This is the first report of a Plasmodium blood parasite found in the Galapagos Archipelago. Phylogenetic analyses place this parasite, recovered from endangered Galapagos penguins (Spheniscus mendiculus), within the genus Plasmodium, and suggest a close relationship to some of the most dangerous lineages of Plasmodium that have been known to cause severe mortality and morbidity in captive penguin populations. Infectious disease is an increasingly important cause of global species extinctions, and extinctions due to avian pox and avian malaria (Plasmodium relictum) have been well documented in Hawaiian avifauna. Plasmodium blood parasites had not been detected in Galapagos birds until now, despite previous microscopic and molecular screening of many of the species, including the Galapagos penguin. While penguin populations now appear healthy, it is unclear whether this parasite will have an obvious impact on their survival and reproduction, particularly during El Niño events, which cause stress due to reduced food availability. It is possible that this parasite arrived with or shortly after the recent arrival of an introduced mosquito, Culex quinquefasciatus, known elsewhere as a competent vector of Plasmodium blood parasites.     

Comparison ofDaphnia magna,rainbow trout and bacterial-based toxicity tests of Ontario Hydro aquatic effluents

Over a one year program of intensive monitoring of effluents from Ontario Hydro's nuclear, fossil and hydroelectric generating facilities, theDaphnia magna and rainbow trout,Oncorhynchus mykiss, acute toxicity tests correlated well, with 61 % of the toxic effluents toxic to both species. If the effluent was toxic to only one of the test species it was generally toxic toD. magna, with from 23 to 57% of the toxic effluents toxic toD. magna only. The greater sensitivity ofD. magna to boiler blowdown effluent likely resulted from a combination of the low conductivity of boiler blowdown effluent and the smaller size and greater surface to volume ratio ofD. magna relative to rainbow trout.D. magna were also particularly susceptible to oil/water separator samples, with the daphnids frequently observed to be caught at the surface/water interface. These observations suggest that an accumulation of organic material at the air/water interface was responsible for the mortality ofD. magna. In subsequent tests, we also examined the relationship between theD. magna acute toxicity test and a bacterial-based assay (Toxi-Chromotest®) for several toxic effluents from Ontario Hydro stations to determine if bacterial-based tests could provide similar information in less time with smaller sample volumes. TheD. magma acute toxicity test did not correlate well with the bacterial-based Toxi-chromotest®. In particular, many of the samples which were toxic toD. magna were not toxic to the Toxi-chromotest® assay. The poor correlation between theD. magna and Toxi-chromotese® likely relates to both the relatively low toxicity of many of the effluent samples, and the fact that in many cases toxicity likely resulted from relatively simple combinations of inorganic toxicants. Accordingly, the Toxi-Chromotest® assay would not seem suitable as a surrogate for theD. magna acute toxicity test for our effluents.     

A risk analysis for the common hamster (Cricetus cricetus)

The common hamster (Cricetus cricetus) has suffered a dramatic decline in Western Europe though the species is characterized by an extremely high reproductive potential. An individual-based model was developed to determine the risk factors which lead to population decline and to investigate management actions for viable populations. Demographic stochasticity was considered by (a) describing reproduction on an individual basis and (b) distinguishing behavioural patterns according to age and sex. Unknown model parameters were determined by comparing field data and simulated patterns in a specific multi-criteria fashion. We conclude that disturbances such as agricultural management and highway construction are most dangerous to the common hamster in autumn. Complex land management is required which should aim at reducing habitat-specific mortality and favouring the safeguarding of adult and subadult females to protect the most sensitive component of the population. According to the model results, large habitat size is not sufficient for survival, and habitat connectivity may be even more important. Late timing of the harvest and following cultivations was most favourable for population survival.