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Earthworms contribute to a wide range of process that underpin soil function and ecosystem services and are an important component of a soil's natural capital stocks. With increasing interest in soil health, it is important to better understand the type of earthworm community required to enhance soil functions. This is of particular interest in New Zealand where pasture systems are dominated by exotic earthworm species and low ecological diversity. Two separate mesocosm experiments were established to explore the interaction between earthworm abundance and ecological diversity as it influences soil functions. Experimental increases in earthworm abundance increased soil macroporosity and water infiltration, increased plant nitrogen (N) and plant growth. Although some benefits were observed at the lowest earthworm abundances, the greatest benefits were seen at the higher abundances. Earthworm ecological diversity is also critical to ensure soil functions are optimised. For example, the single species of Aporrectodea caliginosa alone was not able to improve water infiltration or pasture production. However, when this species was found in combination with Aporrectodea longa, there was positive influence on soil functions despite the abundance of A. longa itself not increasing. This study highlights the importance of including a measure of ecological diversity alongside a measure of abundance to assess soil biological health. Keywords: biological indicator, earthworm abundance, earthworm ecological groups, ecosystem services, mesocosms, plant growth, soil health, water infiltration., Introduction Earthworms are ecosystem engineers, significantly altering the ecosystem they live in (Jones et al. 1994). Earthworms feed on organic matter, ensuring its decomposition and incorporation, increasing plant available nutrients, [...]

Warming global temperatures are expected to strongly influence plant communities, yet there is limited knowledge of how these changes will interact with stressors such as the invasion of exotic earthworms. We conducted a small-scale microcosm experiment to assess the individual and interactive effects of warming and exotic anecic earthworms (Lumbricus terrestris L.) on the growth of sugar maple (Acer saccharum Marsh.) seedlings. After 50 days, the elevated-temperature chamber created warmer and drier soil conditions and increased several measures of plant growth, including stem width, ratio of stem width to stem height, stem biomass, and fine-root biomass. Earthworms did not have any clear impacts on plant growth on their own nor in interactions with the temperature chambers. However, earthworms both reduced surface leaf litter cover and exposed soils, which could exacerbate evaporative losses and moisture stress in field soils resulting from a warming climate under different growing conditions. Future studies should consider the long-term effects of earthworm-temperature interactions on sugar maple growth, as well as diurnal and seasonal changes in temperature. Key words: Lumbricus terrestris, Acer saccharum, earthworm density, climate change, invasive species. Le rechauffement global devrait fortement influencer les communautes vegetales mais on connait mal la facon dont ces changements vont interagir avec des facteurs de stress tels que l'invasion de vers de terre exotiques. Nous avons realise une experience a petite echelle en microcosme pour evaluer les effets individuels et interactifs du rechauffement et des vers de terre aneciques exotiques (Lumbricus terrestris L.) sur la croissance de semis d'erable a sucre (Acer saccharum Marsh.). Apres 50 jours, les chambres a temperature elevee ont cree des conditions du sol plus chaudes et plus seches et augmente plusieurs metriques de la croissance des plants, incluant la largeur de la tige, le rapport de la largeur sur la hauteur de la tige, la biomasse de la tige et la biomasse des racines fines. Les vers de terre n'ont eu aucun impact evident sur la croissance des plants soit directement, soit par le biais d'interactions avec les enceintes thermiques. Cependant, les vers de terre ont reduit l'etendue du couvert de litiere de feuilles et expose les sols, ce qui pourrait amplifier les pertes par evaporation et le stress hydrique dans les sols au champ resultant du rechauffement du climat sous differentes conditions de croissance. Les etudes futures devraient s'interesser aux effets a long termes des interactions entre les vers de terre et la temperature sur la croissance de l'erable a sucre ainsi qu'aux variations diurne et saisonniere de la temperature. [Traduit par la Redaction] Mots-cles: Lumbricus terrestris, Acer saccharum, densite des vers de terre, changement climatique, especes invasives., Introduction Anthropogenic greenhouse gas emissions are contributing to rapid and unprecedented change in global ecosystems, including rises in temperature that have been observed since the 1950s (Intergovernmental Panel on Climate [...]

Because the extensive use of Cu-based fungicides, the accumulation of Cu in agricultural soil has been widely reported. However, little information is known about the bioavailability of Cu deriving from different fungicides in soil. This paper investigated both the distribution behaviors of Cu from two commonly used fungicides (Bordeaux mixture and copper oxychloride) during the aging process and the toxicological effects of Cu on earthworms. Copper nitrate was selected as a comparison during the aging process. The distribution process of exogenous Cu into different soil fractions involved an initial rapid retention (the first 8 weeks) and a following slow continuous retention. Moreover, Cu mainly moved from exchangeable and carbonate fractions to Fe-Mn oxides-combined fraction during the aging process. The Elovich model fit well with the available Cu aging process, and the transformation rate was in the order of Cu(NO 3 ) 2 > Bordeaux mixture > copper oxychloride. On the other hand, the biological responses of earthworms showed that catalase activities and malondialdehyde contents of the copper oxychloride treated earthworms were significantly higher than those of Bordeaux mixture treated earthworms. Also, body Cu loads of earthworms from different Cu compounds spiked soils were in the following order: copper oxychloride > Bordeaux mixture. Thus, the bioavailability of Cu from copper oxychloride in soil was significantly higher than that of Bordeaux mixture, and different Cu compounds should be taken into consideration when studying the bioavailability of Cu-based fungicides in the soil. [ABSTRACT FROM AUTHOR]

Assessment of organophosphorus (OP) pesticide exposure in non-target organisms rarely involves non-neural molecular targets. Here we performed a 30-d microcosm experiment with Lumbricus terrestris to determine whether the activity of digestive enzymes (phosphatase, β-glucosidase, carboxylesterase and lipase) was sensitive to chlorpyrifos (5 mg kg−1 wet soil). Likewise, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities were measured in the wall muscle and gastrointestinal tissues as indicators of OP exposure. Chlorpyrifos inhibited the acid phosphatase (34% of controls), carboxylesterase (25.6%) and lipase activities (31%) in the gastrointestinal content. However, in the gastrointestinal tissue, only the carboxylesterase and lipase activities were significantly depressed (42-67% carboxylesterase inhibition in the foregut and crop/gizzard, and 15% lipase inhibition in the foregut). Chlorpyrifos inhibited the activity of both cholinesterases in the gastrointestinal tissues, whereas the AChE activity was affected in the wall muscle. These results suggested chlorpyrifos was widely distributed throughout the earthworm body after 30 d of incubation. Interestingly, we found muscle carboxylesterase activity strongly inhibited (92% of control) compared with that detected in the gastrointestinal tissues of the same OP-exposed individuals. This finding was explained by the occurrence of pesticide-resistant esterases in the gastrointestinal tissues, which were evidenced by zymography. Our results suggest that digestive processes of L. terrestris may be altered by chlorpyrifos, as a consequence of the inhibitory action of the insecticide on some digestive enzymes. [ABSTRACT FROM AUTHOR]

Many of the world's findings indicate the positive effect of earthworms on soil parameters, and consequently, on the formation of phytomass of cultivated plants. In our experiment we studied: A) the influence of soil itself, soil mixed with vermicompost in a ratio of 9:1; B) the influence of earthworms number (genus Eisenia foetida, 10 and 20 individuals per pot) supplied to soil mixed with vermicompost in the ratio of 9:1 on the dynamics of changes in the weight of radish roots, the total chlorophyll content in leaves and the selected qualitative parameters of the roots. The results obtained showed that one tenth proportion of vermicompost from the total weight of soil substrate caused the statistically significant increase in the total chlorophyll content in leaves, the increase in yield of radish roots, the reduction of the vitamin C content and the increase of nitrate content in the roots. The impact of earthworms on the chlorophyll content in leaves and on the root weight was negative. The addition of 10 individuals of earthworms into 20 kg of substrate (soil + vermicompost) resulted in the increased content of vitamin C and the decreased content of nitrates in the radish roots. Twenty earthworms added to vermicompost, compared to vermicompost alone, did not affect the vitamin C content and reduced the nitrate content. [ABSTRACT FROM AUTHOR]

A laboratory experiment, carried out for five months, was designed to assess the effects produced by the neonicotinoid Actara 25 WG, used at a dose recommended by the manufacturer, in the dynamics of the populations of epigeic Eisenia fetida (Sav.) and Dendrobena veneta (Rosa)earthworms. The study was conducted in a climatic chamber and involved balanced biomass of mature specimens representing both species, in 3 replications of soil medium with the insecticide, in addition to controls. The growing populations were inspected five times, by means of manual segregation of the substrate. The insecticide led to an increase in both the number of specimens and the biomass of E. fetida population (overall, as well as mature and immature worms), yet it reduced their reproduction (decreased the number of cocoons) (p<0.05). In the case of D.veneta, the neonicotinoid insecticide produced positive effects only in the mature specimens (p<0.05). [ABSTRACT FROM AUTHOR]

It is often claimed that earthworms exert a huge influence on soil macroporosity. Nevertheless, gaps still exist in our knowledge of rangeability in soil macroporosity caused by earthworm activity. Earthworms are generally recognized as ecosystem engineers vital for soil ecosystem function and services, but the potential mechanism of earthworm response to the combination of extreme drought and conservation tillage has not yet been identified. To improve understanding of the effect of the earthworm on soil macroporosity and how earthworms, through soil macroporosity, respond to extreme drought and conservation tillage, a study was conducted to compare soil macroporosity under different tillage treatments with the same number of earthworms in incubation conditions and soil structural properties (soil penetration resistance, infiltration rate, saturated hydraulic conductivity) associated with macroporosity, together with crop yields under different tillage systems and drought stress in field conditions. The results show that earthworms only increase the volume of large macropores (>100 μm) rather than small macropores (30-100 μm) under different tillage systems. Earthworms played a positive role in the development of large macropores, as evidenced by the formation of paths of least resistance under high penetration resistance, higher infiltration rate and saturated hydraulic conductivity and no obvious yield loss under extreme drought and conservation tillage in a Chinese Mollisol. [ABSTRACT FROM AUTHOR]

Soil microbial population, earth worms in soil, soil enzyme activity and organ carbon content in soil are considered as the bio indicators of soil health. They are used as indicators of soil health because of their active role in soil organic matter production, decomposition of xenobiotics and cycling of nutrients, ease of measurement and rapid response to changes in management practices. The assessment of soil health can be used to develop more sustainable crop production system. A number of herbicides have been introduced as pre and post emergence weed killer. The impact of herbicides on soil health depends on the soil type, type and concentration of herbicide used, sensitivity to non-target organisms and environmental conditions. The review elaborates the impact of herbicidal application on the biological indicators of soil health. [ABSTRACT FROM AUTHOR]

An ecotoxicological survey of soils that were polluted with wastes from lindane (γ-HCH) production assessed the effects of organochlorine compounds on the metabolism of microbial communities and the toxicity of these compounds to a native earthworm ( Allolobophora chlorotica ). Furthermore, the bioremediation role of earthworms as facilitators of soil washing and the microbial degradation of these organic pollutants were also studied. Soil samples that presented the highest concentrations of ε-HCH, 2,4,6-trichlorophenol, pentachlorobenzene and γ-HCH were extremely toxic to earthworms in the short term, causing the death of almost half of the population. In addition, these soils inhibited the heterotrophic metabolic activity of the microbial community. These highly polluted samples also presented substances that were able to activate cellular detoxification mechanisms (measured as EROD and BFCOD activities), as well as compounds that were able to cause endocrine disruption. A few days of earthworm activity increased the extractability of HCH isomers (e.g., γ-HCH), facilitating the biodegradation of organochlorine compounds and reducing the intensity of endocrine disruption in soils that had low or medium contamination levels. [ABSTRACT FROM AUTHOR]

The present study has been carried out to examine the role of earthworms in phytoremediation of Cd and its effect on growth, pigment content, expression of genes coding key enzymes of pigments, photosynthetic efficiency and osmoprotectants in Brassica juncea L. plants grown under cadmium (Cd) metal stress. The effect of different Cd concentrations (0.50, 0.75, 1.0, 1.25 mM) was studied in 30 and 60-day-old plants grown in soils containing earthworms. It was observed that earthworm inoculation showed stimulatory effect on phytoremediation capacity and Cd uptake has increased by 49% (in 30-day-old plants) and 35% (in 60-day-old plants) in shoots and 13.3% (in 30-day-old plants) and 10% (in 60-day-old plants) in roots in 30 and 60-day-old plants in Cd (1.25 mM) treatments. Plant growth parameters such as root and shoot length, relative water content and tolerance index were found to increase in the presence of earthworms. Recovery in photosynthetic pigments (chlorophyll and carotenoid) and gas exchange parameters, i.e. net photosynthetic rate ( P ), stomatal conductance ( G ), intercellular CO concentration ( C ) and transpiration rate ( E ), was observed after earthworm's supplementation. Modulation in expression of key enzymes for pigment synthesis, i.e. chlorophyllase, phytoene synthase, chalcone synthase and phenylalanine ammonia lyase, was also observed. The results of our study revealed that earthworms help to mitigate the toxic effects produced by Cd on plant growth and photosynthetic efficiency along with enhanced phytoremediation capacity when co-inoculated with Cd in soil. [ABSTRACT FROM AUTHOR]

The characteristic properties of uptake and distribution of mercury in terrestrial ecosystems have received much lesser attention compared to aquatic particularly in Russia. Terrestrial ecosystems adjacent to large industrial manufactures-potential sources of mercury inflow into the environment frequently remain unstudied. This is the first report on mercury (Hg) levels in the basic elements of terrestrial ecosystems situated close to a large metallurgical complex. Mean values of mercury concentration (mg Hg/kg dry weight) in the vicinity of city of Cherepovets were the following: 0.056 ± 0.033-in the humus layer of soil; 0.556 ± 0.159-in earthworms; in the organs of voles Myodes glareolus (kidneys-0.021 ± 0.001; liver-0.014 ± 0.003; muscle-0.014 ± 0.001; brain-0.008 ± 0.002); in the organs of shrew Sorex araneus (kidneys-0.191 ± 0.016; liver-0.124 ± 0.011; muscle-0.108 ± 0.009; brain-0.065 ± 0.000). Correlation dependences between Hg content in soil and earthworms ( r = 0.85, p < 0.01) as well as soil and all studied shrews' organs ( rs = 0.44-0.58; p ≤ 0.01) were found. The results obtained evidence for a strong trophic link in the bioaccumulation of Hg in terrestrial food webs. Despite the vicinity to a large metallurgical complex, mercury content in the studied objects was significantly lower than values of corresponding parameters in the soils and biota from industrial (polluted) areas of Great Britain, the USA, and China. [ABSTRACT FROM AUTHOR]

Given the substantial impacts of non-native species on invaded systems, an understanding of the rates and spatial patterns of invasive spread is critical. Spread may vary across spatial scales, with dispersal of invasive species occurring both via diffusive spread at local sites and long-distance jump dispersal at larger scales. Research on earthworm invasions in North American forests has focused on patterns of spread across landscapes, with less examination of spread at local sites. We sampled the exotic earthworm Dendrobaena octaedra (Savigny, 1826) on 500 m x 500 m grids at three sites in the boreal forest of northeastern Alberta in 2006 and again in 2012-2013 to examine distributional changes over time. Earthworms spread farther from roads (the presumed site of initial introduction) over time, and spatial patterns at our sites suggest transport by vehicles and waterways are key vectors of dispersal at the local level. Spread was estimated to be occurring at a rate of at least 17.9 m/year. Our study indicates that both diffusive spread and jump dispersal of earthworms can be important at local scales and that local diffusive spread may be substantially higher than previously estimated. Key words: boreal forest, Dendrobaena octaedra, earthworms, invasive species, local spread, spatial pattern, spread rate. Etant donne les impacts considerables des especes non indigenes sur les systemes envahis, la comprehension des taux et de la distribution spatiale de la dissemination envahissante est d'une importance critique. La dissemination peut varier selon l'echelle spatiale, la dispersion d'especes envahissantes s'effectuant tant par dissemination par diffusion a l'echelle locale que par dispersion par grands sauts a des echelles plus grandes. La recherche sur les invasions de lombrics dans les forets nordamericaines s'est axee sur les motifs de dissemination a l'echelle des paysages, s'interessant moins a la dissemination locale. Nous avons echantillonne du lombric exotique Dendrobaena octaedra (Savigny, 1826) sur des grilles de 500 m x 500 m en trois sites dans la foret boreale du nord-est de l'Alberta en 2006, puis en 2012-2013, afin d'examiner les variations de leur repartition dans le temps. La dissemination des lombrics s'eloignait des routes (sites presumes de l'introduction initiale) avec le temps, les motifs de repartition spatiale dans les sites etudies donnant a penser que les vehicules et les cours d'eau constituent des vecteurs cles de la dispersion a l'echelle locale. Il a ete estime que la dissemination s'effectuait a un taux d'au moins 17,9 m/an. Notre etude indique que tant la dissemination par diffusion que la dispersion par sauts des lombrics peuvent etre importantes a des echelles locales et que la dissemination locale par diffusion peut etre sensiblement plus importante que ce que laissaient croire les estimations passees. [Traduit par la Redaction] Mots-cles: foret boreale, Dendrobaena octaedra, lombrics, espece envahissante, dissemination locale, motif spatial, taux de dissemination., Introduction Information on the spread of non-native species is essential for predicting and managing invasions. However, determining rates of spread is challenging because data from multiple time points and across [...]

Background: Soil contamination and associated pollution plays a detrimental role in soil flora and fauna. Soil is processed and remodeled by subterranean earthworms, accordingly are referred to as soil chemical engineers. These worms, besides processing carbon and nitrogen, serve as minors for processing metals. In heavy metal contaminated soils, they accumulate heavy metals, which in turn cause altered gene expression, including aldehyde dehydrogenase (ALDH) enzymes. This study explores the possibility of ALDH expression in earthworms as a novel biomarker for the heavy metal contamination of soil. Results: Earthworms cultured in contaminated soils accumulated significantly higher levels of Pb and Cd. Similarly, significantly higher levels of ALDH enzyme activities were observed in earthworms cultured in soils contaminated with Pb and Cd. The ALDH activity was found to be highest in worms cultured in 5 ppm heavy metal contaminated soils. Although, ALDH activities decreased as the heavy metal concentration in soil increased, they were significantly higher when compared to control worms cultured in uncontaminated soils. The accumulation of heavy metal in earthworms measured after 28 days decreased as the heavy metal concentration in soil increased. Conclusions: Levels of ALDH expression correlated with total Pb and Cd concentration in the earthworm tissue. This study showed that the ALDH activity in earthworms could potentially be used as a biomarker to show heavy metal pollution in soil. [ABSTRACT FROM AUTHOR]

Vermicomposting is a decomposition process involving the joint action of earthworms and microorganisms. Although microorganisms are responsible for the biochemical degradation of organic matter, earthworms are crucial drivers of the process, by fragmenting and conditioning the substrate and significantly altering its biological activity. The purpose of the work was to assess the influence of vermicompost based growth substrates on tomato transplant growth. Treatments were followed (supplier K. Compos): A) 30% vermicompost, peat, sand and dolomite stone; B) 25% vermicompost, peat, gravel, perlite; C) 25% vermicompost, peat, gravel, concrete block; D) commercially produced growth substrate bought from retail centre, as a control. Substrates containing vermicompost had increased stem diameter compared to control treatment. The tomato plant height was increased in substrates containing 25% vermicompost compared to other treatments. The number of leaves was highest in treatment C compared to other treatments. The number of flowers was increased in treatment A and lowest in treatment D. It can be summarized that for tomato the best growth substrate, regarding growth parameters is 25% vermicompost, peat, gravel, concrete block (treatment C). [ABSTRACT FROM AUTHOR]

This study aimed at assessing the influence of soil properties on the uptake and toxicity effects of arsenic in the earthworm Eisenia andrei exposed for 4 weeks to seven natural soils spiked with different arsenic concentrations. Water-soluble soil concentrations (AsW) and internal As concentrations in the earthworms (AsE) were greatly different between soils. These two variables were highly correlated and were key factors in earthworm toxicity response. AsW was explained by some soil properties, such as the pH, calcium carbonate content, ionic strength, texture or oxide forms. Toxicity showed a clear variation between soils, in some cases without achieving 50 % adverse effect at the highest As concentration added (600 mg kg). Nevertheless, soil properties did not show, in general, a high relation with studied toxicity endpoints, although the high correlation with AsW could greatly reduce indirectly As bioavailability and toxicity risk for earthworms. Obtained results suggest that soil properties should be part of the criteria to establishing thresholds for contaminated soils because they will be key in controlling As availability and thus result in different degrees of toxicity. [ABSTRACT FROM AUTHOR]

BACKGROUND Enantiomers of chiral pesticides often have different bioactivity, toxicity and environmental behaviours. Fipronil has been used in racemate for agricultural purposes against soil insects, leading to increased inputs into soil environments and complex biota exposures. To understand the potential risk associated with fipronil enantiomer exposure, subchronic toxicity and bioaccumulation tests with earthworms ( Eisenia foetida) in fipronil-spiked soils were evaluated under laboratory conditions. RESULTS Enantioselective toxicity was measured in E. foetida biomass after 28 days of subchronic exposure, with increased toxicity from racemate and S-fipronil compared with R-fipronil. The bioaccumulation of fipronil in earthworm tissues was also enantioselective, with a preferential accumulation of S-fipronil, and the enantiomer fraction was approximately 0.56-0.60. During soil exposure, fipronil was transformed primarily into fipronil sulfide, sulfone and amide, and E. foetida rapidly accumulated fipronil and sulfone. CONCLUSION This work demonstrates the enantioselective subchronic toxicity and bioaccumulation of enantiomers of fipronil in E. foetida. The earthworm tissues exhibited a relative enrichment of fipronil and fipronil sulfone, and these compounds might biomagnify (with a biota-to-soil accumulation factor of ≥1.0 [ABSTRACT FROM AUTHOR]

A comprehensive and quantitative knowledge of ecological factors affecting crop production is needed in purpose to meet the challenge of growing world population with minimal environmental impact. Earthworms are target organisms both for scientists studying the biological component of soils and for farmers concerned with monitoring the quality of their soils. For the growing social interest to quantify the role of earthworms in ecosystems, a precise and accurate estimation of their diversity, abundance and biomass is needed. Earthworm ecologists tend to use methods of extraction with less use of chemicals, with this purpose we want to test some new environmental friendly methods like chili powder, mustard powder, mustard-vinegar suspension, in comparison with formalin 0.1% (10 ml in 8 l water) and 0.2% (15 ml in 8 l water). Efficiency of methods is compared in terms of earthworm species composition, numbers, biomass, ecological groups (epigeic, anecic, endogeic), development stages (adults + subadults vs. juveniles) and the mortality rates in the first week after sampling. [ABSTRACT FROM AUTHOR]

Invasional meltdowns, in which facilitation between species causes an accelerating increase in the number of introduced species or impacts, can cause large impacts in invaded systems. Earthworm invasion of northern forests has been suggested as a meltdown, with litter-dwelling species altering soil structure and facilitating mineral-soil or deep- burrowing earthworms that may be less capable of invading intact forest floors. We examined facilitation and synergistic effects of a litter-dwelling species (Dendrobaena octaedra Savigny, 1826) and a deep-burrowing species (Lumbricus terrestris L., 1758). Boreal forest soil cores were inoculated with D. octaedra, L. terrestris, both species, a higher density of L. terrestris, or no worms. After 4.5 months, we found no differences in survival or biomass between treatments for either species. Cocoon production did not differ for L. terrestris, but D. octaedra produced significantly fewer cocoons with L. terrestris. The two species had an additive effect on organic horizon depths and bulk densities. Thus, they did not appear to facilitate each other or have synergistic effects as would be predicted in an invasional meltdown. Les effondrements associes aux invasions, dans lesquels la facilitation entre les especes augmente le nombre D'especes introduites ou leurs impacts, peuvent avoir de fortes repercussions sur les systemes envahis. On a suggere que L'invasion des forets nordiques par les vers de terre est un effondrement dans lequel les especes vivant dans la litiere alterent la structure des sols et facilitent la presence de vers de terre des sols mineraux ou de ceux qui s'enfoncent profondement et qui peuvent etre moins capables d' envahir les sols forestiers intacts. Nous examinons la facilitation et les effets synergiques d'une espece vivant dans la litiere (Dendrobaena octaedra Savigny, 1826) et d'une autre qui s'enfonce profondement (Lumbricus terrestris L., 1758). Nous avons inocule des carottes de sol de foret boreale soit avec D. octaedra, L. terrestris, les deux especes, une plus forte densite de L. terrestris, ou alors aucun ver. Au bout de 4,5 mois, il n'y a aucune difference de survie ou de biomasse des deux especes entre les traitements. La production de cocons ne differe pas chez L. terrestris, mais D. octaedra produit significativement moins de cocons en presence de L. terrestris. Les deux especes ont un effet additif sur la densite brute et la profondeur de l'horizon organique. Ainsi, elles ne semblent pas se faciliter l'une l'autre, ni avoir d'effets synergiques comme on l'aurait predit dans le cas d'un effondre-ment lie aux invasions. [Traduit par la Redaction], Introduction The frequency and geographic extent of biological invasions are increasing worldwide, to the detriment of many native taxa (Cohen and Carlton 1998; Ricciardi 2001; Lockwood et al. 2007). With [...]

Scientists are beginning to have a firm grasp on the dramatic influence invasive earthworms can have on nutrient cycling in northern hardwood forests, yet a concrete understanding of their effects on plant communities is still needed. Towards this effort, we examined both the above and belowground plant communities, along with soil organic matter, pH, texture and light in Arnot Forest located in south central New York. Two transects were aligned parallel to previously defined gradients of earthworm density and were sampled in the spring and summer of 2008. We found plots codominated by multiple earthworm species decreased belowground seed abundance and species richness. Aboveground plant cover and diversity along with soil organic matter was lower along the transect with multiple earthworm species. In addition, we found earthworm density increased with soil pH, but did not detect relationships with soil texture or light intensity. Our results were consistent with previous findings of earthworms negatively affecting aboveground plant communities and soil organic matter, and increasing pH. Our study demonstrates the potential for exotic earthworms to dramatically alter forest soil seed banks; however, future research is needed to investigate complexities of earthworm community dynamics (e.g., number and life form of earthworm species) and to tease apart mechanisms responsible for changes in the belowground plant community., INTRODUCTION A growing body of literature has found invasive earthworms in northern hardwood forests to cause remarkable changes in soil structure, nutrient cycling and plant communities. Perhaps the most striking [...]

Earthworms of the family Lumbricidae, which includes many common species, produce and secrete up to millimeter-sized calcite granules, and the intricate fine-scale zoning of their constituent crystals is unique for a biomineral. Granule calcite is produced by crystallization of amorphous calcium carbonate (ACC) that initially precipitates within the earthworm calciferous glands, then forms protogranules by accretion on quartz grain cores. Crystallization of ACC is mediated by migrating fluid films and is largely complete within 24 h of ACC production and before granules leave the earthworm. Variations in the density of defects formed as a byproduct of trace element incorporation during calcite crystal growth have generated zoning that can be resolved by cathodoluminescence imaging at ultraviolet to blue wavelengths and using the novel technique of scanning electron microscope charge contrast imaging. Mapping of calcite crystal orientations by electron backscatter diffraction reveals an approximate radial fabric to the granules that reflects crystal growth from internal nucleation sites toward their margins. The survival within granules of ACC inclusions for months after they enter soils indicates that they crystallize only within the earthworm and in the presence of fluids containing biochemical catalysts. The earthworm probably promotes crystallization of ACC in order to prevent remobilization of the calcium carbonate by dissolution. Calcite granules vividly illustrate the role of transient precursors in biomineralization, but the underlying question of why earthworms produce granules in volumes sufficient to have a measurable impact on soil carbon cycling remains to be answered.

The role of species and functional group diversity of primary producers for decomposers and decomposition processes is little understood. We made use of the 'Jena Biodiversity Experiment' and tested the hypothesis that increasing plant species (1, 4, and 16 species) and functional group diversity (1, 2, 3, and 4 groups) beneficially affects decomposer density and activity and therefore the decomposition of plant litter material. Furthermore, by manipulating the densities of decomposers (earthworms and springtails) within the plant diversity gradient we investigated how the interactions between plant diversity and decomposer densities affect the decomposition of litter belonging to different plant functional groups (grasses, herbs, and legumes). Positive effects of increasing plant species or functional group diversity on earthworms (biomass and density) and microbial biomass were mainly due to the increased incidence of legumes with increasing diversity. Neither plant species diversity nor functional group diversity affected litter decomposition. However, litter decomposition varied with decomposer and plant functional group identity (of both living plants and plant litter). While springtail removal generally had little effect on decomposition, increased earthworm density accelerated the decomposition of nitrogen-rich legume litter, and this was more pronounced at higher plant diversity. The results suggest that earthworms (Lumbricus terrestris L.) and legumes function as keystone organisms for grassland decomposition processes and presumably contribute to the recorded increase in primary productivity with increasing plant diversity. Key words: decomposers; functional groups; 'Jena Experiment'; legumes, litter type; Lumbricidae; Lumbricus terrestris; nitrogen; soil fauna; species richness.

Background: Studying the drivers and determinants of species, population and community spatial patterns is central to ecology. The observed structure of community assemblages is the result of deterministic abiotic (environmental constraints) and biotic factors (positive and negative species interactions), as well as stochastic colonization events (historical contingency). We analyzed the role of multi-scale spatial component of soil environmental variability in structuring earthworm assemblages in a gallery forest from the Colombian "Llanos." We aimed to disentangle the spatial scales at which species assemblages are structured and determine whether these scales matched those expressed by soil environmental variables. We also tested the hypothesis of the "single tree effect" by exploring the spatial relationships between root-related variables and soil nutrient and physical variables in structuring used, namely cross-correlograms, Principal Coordinates of Neighbor Matrices (PCNM) and variation partitioning analyses earthworm assemblages. Multivariate ordination techniques and spatially explicit tools were Results: The relationship between the spatial organization of earthworm assemblages and soil environmental parameters revealed explicitly multi-scale responses. The soil environmental variables that explained nested population structures across the multi-spatial scale gradient differed for earthworms and assemblages at the very-fine-(<10 m) to medium-scale (10-20 m). The root traits were correlated with areas of high soil nutrient contents at a depth of 0-5 cm. Information on the scales of PCNM variables was obtained using variogram modeling. Based on the size of the plot, the PCNM variables were arbitrarily allocated to medium (>30 m), fine (10-20 m) and very fine scales (<10 m). Variation partitioning analysis revealed that the soil environmental variability explained from less than 1% to as much as 48% of the observed earthworm spatial variation Conclusions: A large proportion of the spatial variation did not depend on the soil environmental variability for certain species. This finding could indicate the influence of contagious biotic interactions, stochastic factors, or unmeasured relevant soil environmental variables. [ABSTRACT FROM AUTHOR]

The aim of this work is to evaluate the effect of Parthenium-mediated compost on Eudrilus eugeniae during the process of vermicomposting. Nine different concentrations of Parthenium hysterophorus and cow dung mixtures were used to assess toxicity. The earthworms' growth, fecundity and antioxidant enzyme levels were analysed every 15 days. The antioxidant activities of enzymes [superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)], considered as biomarkers, indicate the biochemical and oxidative stresses due to the toxin from Parthenium weeds. The earthworms' growth, biomass gain, cocoon production and antioxidant enzymes were in a low level in a high concentration of P. hysterophorus (without cow dung). The results clearly indicated that appropriate mixing of P. hysterophorus quantity is an essential factor for the survival of earthworms without causing any harm. [ABSTRACT FROM AUTHOR]

Elevated levels of inorganic nitrogen (N) deposition and earthworm invasion have the potential to alter N dynamics in eastern North American temperate forests. A regional comparison was conducted across 21 sugar maple ( Acer saccharum Marsh) stands in southern Ontario, where forest floor C:N ratios ranged from 17 to 38 showed that, similar to many other studies, rates of potential net mineralization and nitrification increased below a forest floor C:N ratio threshold of approximately 25 and that nitrification rates are positively correlated with foliar N concentration. However, detailed measurements at four representative stands, receiving between 9.8 and 19 kg N ha y in throughfall, showed that foliar N levels were highest at the site with the lowest N deposition. The primary difference amongst these sites was the presence of invasive earthworms. Specifically, sites without earthworms had significantly higher forest floor N with a lower C:N ratio than the sites with earthworms. There was no significant difference in the rate of sugar maple litter decomposition or chemistry amongst the sites assessed after 540 days using fine (2-mm mesh) litter bags, suggesting that differences in forest floor N levels were most likely due to consumption of litter by large earthworm species and that the lower C:N ratio of the forest floor in sites without earthworms is brought about primarily by a much longer residence time. This work supports the conclusions that forest floor N concentration (or C:N ratio) has a very strong control on N dynamics in forests, but shows that the presence of earthworms can have an impact on forest floor C:N ratio and hence N dynamics that is greater than current levels of atmospheric inorganic N deposition in temperate forests of Ontario. [ABSTRACT FROM AUTHOR]

The article presents research which examined the ecological effects of invasive earthworms in Kamchatka, Russia. Topics covered include the diversity of earthworms in the area's anthropogenic and natural habitats and the results of the deoxyribonucleic acid (DNA) barcoding of the species. Also mentioned is the use of the species as an effective model for understanding how earthworm invades previously earthworm-free areas.

Earthworms provide key soil functions that favour many positive ecosystem services. These services are important for agroecosystem sustainability but can be degraded by intensive cultural practices such as use of pesticides. Many literature reports have investigated the effect of pesticides on earthworms. Here, we review those reports to assess the relevance of the indicators of earthworm response to pesticides, to assess their sensitivity to pesticides, and to highlight the remaining knowledge gaps. We focus on European earthworm species and products authorised in Europe, excluding natural compounds and metals. We consider different organisation levels: the infra-individual level (gene expression and physiology), the individual and population levels (life-history traits, population density and behaviour) and the community level: community biomass and density. Our analysis shows that earthworms are impacted by pesticides at all organisation levels. For example, pesticides disrupt enzymatic activities, increase individual mortality, decrease fecundity and growth, change individual behaviour such as feeding rate and decrease the overall community biomass and density. Insecticides and fungicides are the most toxic pesticides impacting survival and reproduction, respectively. [ABSTRACT FROM AUTHOR]

In a pot-cultural experiment, the impact of the antibiotic roxithromycin (ROX) addition was assessed on the diversities of microbial structure and function communities, especially involved in ammonia and nitrite oxidation in wheat rhizosphere soil with and without the addition of earthworms. The abundances of ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), and total bacteria were surveyed by the quantitative PCR. The quantities of total bacteria, AOB, and NOB with earthworms were higher than those without earthworms because of the synergistic effect. ROX inhibited the growth of AOB in all treatments, although the quantities of AOB were in a light increase in medium and heavy polluted treatments compared with that in the light polluted treatments. Different from AOB, the quantities of NOB were lowest in light polluted treatments, but the quantities of NOB were rapidly increased in medium and heavy polluted treatments compared with that in the control. These results indicated that the application of ROX principally had a negative effect on nitrification performance by affecting the abundances and relative ratios of both AOB and NOB in soil communities, which affected the N cycle in an agricultural ecosystem. According to the metabolic diversities evaluated by the biologic assay, the tendency of metabolic diversities was quite contrary to the quantities of NOB in all treatments and showed the contrast growing relation of autotrophic and heterotrophic bacteria under ROX pollution pressure in agricultural ecosystems. [ABSTRACT FROM AUTHOR]

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Changes in earthworm abundance, biomass, and diversity were monitored under a range of tillage and stubble management practices in a wheat/alternative crop rotation over 5 years on a Sodosol (Alfisol) in southern New South Wales, Australia. There were 3 tillage and 2 stubble management practices in a completely randomised block design with 3 replications. The 3 tillage treatments were no-tillage (NT), 1 tillage pass (1T), and 3 tillage passes (3T). Stubble management practices were stubble retained (sr) and stubble burnt (sb). Positive responses of earthworm abundance and biomass to stubble retention (>2-fold increase) were evident in the second year and to both stubble and tillage in the third year. In the latter, abundance in NT/sr was 6.6 times that found under 3T/sb (239 v. 36/[m.sup.2]). Higher earthworm abundance in NT/sr compared with 3T/sb prevailed for the remaining duration of the experiment. However, a drastic decline in total population (to a mean of 31/[m.sup.2]) was observed in the fourth year in all the treatments and this was followed by further decline to a mean abundance of 4/[m.sup.2] in the fifth year. The drastic decline in abundance was also accompanied by a shift in earthworm species composition. The earthworm population was originally dominated by the exotic Lumbrid, Aporrectodea trapezoides (Lumbricidae) (~100% in composition), but by the fifth year, Microscolex dubious (Acanthodrilidae) was the dominant species, making up 75% of the earthworm population in NT/sr. Improvement in soil quality as detected in the fifth year under a conservation tillage system compared with a conventional system included higher transmitting macropores, higher labile carbon, and water-stable aggregation. The reason for the decline in earthworm abundance was not clear but was unlikely related to changes in soil quality, wheat yield, and rainfall. Instead, we suggest that it was related to the changes in insecticide applications during the course of the experiment. The study highlights the importance of judicious use of chemicals in farming systems if earthworm presence is to be encouraged. Additional keywords: no-tillage, labile carbon, insecticides, macropores, Microscolex dubious, Aporrectodea trapezoids., Introduction Benefits and functions of earthworms in agro-ecosystems are being recognised (e.g. Edwards and Bohlen 1996) and it is important to identify the management practices that encourage earthworms in the [...]

Decomposer invertebrates influence soil structure and nutrient mineralization as well as the activity and composition of the microbial community in soil and therefore likely affect plant performance and plant competition. We established model grassland communities in a greenhouse to study the interrelationship between two different functional groups of decomposer invertebrates, Lumbricidae and Collembola, and their effect on plant performance and plant nitrogen uptake in a plant diversity gradient. Common plant species of Central European Arrhenatherion grasslands were transplanted into microcosms with numbers of plant species varying from one to eight and plant functional groups varying from one to four. Separate and combined treatments with earthworms and collembolans were set up. Microcosms contained [sup.15]N labeled litter to track N fluxes into plant shoots. Presence of decomposers strongly increased total plant and plant shoot biomass. Root biomass decreased in the presence of collembolans and even more in the presence of earthworms. However, it increased when both animal groups were present. Also, presence of decomposers increased total N concentration and [sup.15]N enrichment of grasses, legumes, and small herbs. Small herbs were at a maximum in the combined treatment with earthworms and collembolans. The impact of earthworms and collembolans on plant performance strongly varied with plant functional group identity and plant species diversity and was modified when both decomposers were present. Both decomposer groups generally increased aboveground plant productivity through effects on litter decomposition and nutrient mineralization leading to an increased plant nutrient acquisition. The non-uniform effects of earthworms and collembolans suggest that functional diversity of soil decomposer animals matters and that the interactions between soil animal functional groups affect the structure of plant communities. Key words: Collembola; decomposers; functional diversity; Lumbricidae; plant-animal interaction; plant diversity; productivity; The Jena Experiment.

We studied the effects of tree species on leaf litter decomposition and forest floor dynamics in a common garden experiment of 14 tree species (Abies alba, Acer platanoides, Acer pseudoplatanus, Betula pendula, Carpinus betulus, Fagus sylvatica, Larix decidua, Picea abies, Pinus nigra, Pinus sylvestris, Pseudotsuga menziesii, Quercus robur, Quercus rubra, and Tilia cordata) in southwestern Poland. We used three simultaneous litter bag experiments to tease apart species effects on decomposition via leaf litter chemistry vs. effects on the decomposition environment. Decomposition rates of litter in its plot of origin were negatively correlated with litter lignin and positively correlated with mean annual soil temperature ([MAT.sub.soil]) across species. Likewise, decomposition of a common litter type across all plots was positively associated with [MAT.sub.soil], and decomposition of litter from all plots in a common plot was negatively related to litter lignin but positively related to litter Ca. Taken together, these results indicate that tree species influenced microbial decomposition primarily via differences in litter lignin (and secondarily, via differences in litter Ca), with high-lignin (and low-Ca) species decomposing most slowly, and by affecting [MAT.sub.soil], with warmer plots exhibiting more rapid decomposition. In addition to litter bag experiments, we examined forest floor dynamics in each plot by mass balance, since earthworms were a known component of these forest stands and their access to litter in litter bags was limited. Forest floor removal rates estimated from mass balance were positively related to leaf litter Ca (and unrelated to decay rates obtained using litter bags). Litter Ca, in turn, was positively related to the abundance of earthworms, particularly Lumbricus terrestris. Thus, while species influence microbially mediated decomposition primarily through differences in litter lignin, differences among species in litter Ca are most important in determining species effects on forest floor leaf litter dynamics among these 14 tree species, apparently because of the influence of litter Ca on earthworm activity. The overall influence of these tree species on leaf litter decomposition via effects on both microbial and faunal processing will only become clear when we can quantify the decay dynamics of litter that is translocated belowground by earthworms. Key words: calcium; decomposition; earthworms; lignin; litter; N-immobilization; Poland; trees.

In the last decade the invasion of European earthworms into previously worm-free glaciated areas of North America has stimulated research into their impacts on native forest ecosystems in the region. As a first approximation, the impacts of invading earthworms are related to their biomass. However, direct measurements of biomass can be significantly affected by the moisture conditions under which the earthworms are collected and their relative gut contents. Ash-free dry mass is the best standardized measure of earthworm biomass, but requires the destruction of specimens. This paper presents five allometric equations that allow for estimation of ash-free dry biomass based on length (mm) measurements for European earthworm species (Lumbricidae) commonly seen in the United States.

By controlled experiments that simulate marine conditions, it is shown that accelerated weathering and mineral authigenesis occur during the combined process of digestion, ingestion and excretion of sediment by worms. Previously characterized synthetic mud, composed of finely ground, low-grade metamorphic slate dominated by highly crystalline chlorite and muscovite, was unchanged in control tanks over a 20 week time scale, but was significantly different in faecal samples from an experimental tank populated with the annelid Arenicola marina. Chlorite was preferentially destroyed during digestion and both chlorite and muscovite underwent peak broadening with a skew developing towards higher lattice spacings. Neoformed minerals with very high d-spacings and a mineral with 0.75 nm basal lattice spacing (possibly berthierine) were detected in the cast samples. It is postulated that the lowered pH microenvironment in the guts of organisms may accelerate mineral dissolution and precipitation processes during ingestion. These results show that macrobiotic activity significantly accelerates weathering and mineral degradation along with mineral authigenesis. Neoformed minerals produced in this way would be likely to form the precursors of diagenetic clay mineral cements and thus have an impact on sandstone reservoir quality. Keywords: worms, weathering, authigenesis, clay minerals, reservoir quality.

Research has been conducted on the microbial population in the agricultural soil and the earthworm Lumbricus rubellus casts. The culture and culture-independent study of the earthworm casts, burrows and the surrounding agricultural soil has been carried out and the phenotypic properties and partial DNA sequences of the isolates and clones have been examined.

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Four constructed wetland systems were studied to investigate the effects of adding Eisenia fetida on the purifying capacity of constructed wetlands. Addition of E. fetida increased the photosynthetic rate (Pn), transpiration rate (Tr) and chlorophyll meter value of leaves of Iris pseudacorus L. in the constructed wetlands by 16, 35 and 7%, respectively. Compared with the substrate only system, evapotranspiration losses were increased by 8, 48 and 56% for the wetland systems with substrate and E. fetida, with substrate and I. pseudacorus, and with substrate, I. pseudacorus and E. fetida, respectively. Addition of E. fetida to the substrate only and substrate and plant wetland systems decreased the substrate bulk density by 3 and 6%, respectively. The addition of E. fetida to the system with substrate and plants increased the removal efficiency of chemical oxygen demand (CODMn), total nitrogen (TN) and total phosphorus by 5, 7 and 22%, respectively. Evapotranspiration losses were significantly positively correlated with the removal efficiency of CODMn (P<0.01). The significantly negative correlation between the removal efficiency TN and bulk density was found (P< 0.05). Therefore, E. fetida could stimulate I. pseudacorus growth and improve the substrate bulk density in the constructed wetland, resulting in enhanced purifying capacity. [ABSTRACT FROM AUTHOR]

In this paper, we studied the effect of earthworm loads on the removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total nitrogen, and total phosphorus from synthetic domestic sewage and on the bacterial community structure and diversity of substrates in earthworm packing beds. The different vermifiltrations (VFs), including the control, are successful in removing both organic matter (OM) and nutrients. The removal rate of NH3-N at 12.5 g of earthworm/L of soil VF is higher compared with that at 0 and 4.5 earthworm load VFs. The highest Shannon index, in the earthworm packing bed, occurred at 16.5 earthworm load VF. Furthermore, the COD removal rate is significantly correlated with the Shannon index, which reveals that OM removal for synthetic domestic sewage treatment at VF might be more dependent on bacterial diversity at the earthworm packing bed. The band distributions and diversities of the bacterial community for samples from different earthworm loads in VFs suggest that the bacterial community structure was only affected within the earthworm packing bed when the earthworm load reached a certain level. The present study adds to the current understanding of OM and nutrient degradation processes in VF domestic wastewater treatment. [ABSTRACT FROM AUTHOR]

Abstract: The effects of the exposure of earthworms (Eisenia andrei) to contaminated soil from an abandoned uranium mine, were assessed through gene expression profile evaluation by Suppression Subtractive Hybridization (SSH). Organisms were exposed in situ for 56 days, in containers placed both in a contaminated and in a non-contaminated site (reference). Organisms were sampled after 14 and 56 days of exposure. Results showed that the main physiological functions affected by the exposure to metals and radionuclides were: metabolism, oxireductase activity, redox homeostasis and response to chemical stimulus and stress. The relative expression of NADH dehydrogenase subunit 1 and elongation factor 1 alpha was also affected, since the genes encoding these enzymes were significantly up and down-regulated, after 14 and 56 days of exposure, respectively. Also, an EST with homology for SET oncogene was found to be up-regulated. To the best of our knowledge, this is the first time that this gene was identified in earthworms and thus, further studies are required, to clarify its involvement in the toxicity of metals and radionuclides. Considering the results herein presented, gene expression profiling proved to be a very useful tool to detect earthworms underlying responses to metals and radionuclides exposure, pointing out for the detection and development of potential new biomarkers. [Copyright &y& Elsevier]