Exotic Earthworms Research Articles

Impact of Pendimethalin on Growth and Reproduction of Eisenia fetida

Earthworms play a crucial role in soil quality and agricultural practices, and their populations can be influenced by various factors, including the presence of pesticides like pendimethalin used in soybean crop. This study aims to evaluate the toxicity of pendimethalin on Eisenia fetida, a common naturalized exotic earthworm species found in Kota, India. Five sets of 10 worms were exposed to different concentrations of pendimethalin (ranging from 0.474 to 47.4 mg/kg dry weight), with one set of control soil. After four weeks, the growth rate and reproduction of Eisenia fetida were significantly reduced by pendimethalin exposure, highlighting the potential negative impact of this herbicide on soil ecosystems.

Land use effect on dominance of native and exotic earthworm species in two contrasting rural landscapes

Lumbricids and several species of the genus Amynthas have spread over all continents and seem to be better competitors than natives in disturbed ecosystems and agricultural fields. More than half of Uruguay's 19 earthworm species recorded by 2014 are exotic. Aiming to contribute to the scarce information on earthworm ecology in the region, the objectives of this work were 1) to characterize the earthworm communities in agriculture and natural ecosystems, and 2) to assess the relationship between land use and richness of native and exotic earthworm species. Related to the latter objective, we hypothesized that the difference in the number of exotic and native species depended on the degree of disturbance, and predicted that exotic species would dominate in more disturbed soils. We sampled organic and nonorganic agricultural fields including wheat in the rotations in the South and the North-West of Uruguay. Undisturbed sites, i.e. with no recent agriculture activity, close to each sampling plot served as controls. Analyses were conducted to elucidate whether other variables, besides disturbance and location, could be influencing earthworm community structure and composition. In both locations, exotic species dominated in control plots, i.e. less or non-disturbed land, and were associated to higher N, C and soil porosity. Moreover, in the North-West, natives would dominate in terms of richness in most agriculture plots. The mean body weight was larger in the South, where there were more exotic species, than in the North-West, where there were more native species. Thirteen of the collected species had been reported for Uruguay, the four other species found, were reported for the first time in this paper: Microscolex phosphoreus and Glossodrilus parecis (natives); and Aporrectodea tuberculata and Murchieona minuscula (exotics). Finding four unrecorded species evidences the poor coverage of earthworm sampling in anthropic and natural landscapes of the country.

Fourteen-year field experiment reveals neutral effects of N and P deposition on abundance and stoichiometric traits of the earthworm Pontoscolex corethrurus in tropical plantations

The afforestation of tropical forests plays an important role in mitigating climate change. Exploring the impacts of nitrogen (N) and phosphorus (P) deposition on earthworm communities is significant for understanding the contributions of tropical forests to global change. A 14-year field experiment simulating N and P deposition at a station with 50-year-old tropical plantations was conducted. We found that the pantropical widespread exotic earthworm species Pontoscolex corethrurus was dominant, and it did not respond to exogenous N input. Moreover, P addition only increased the abundance of P. corethrurus after 14 years. Similarly, neither N addition nor P addition changed the stoichiometric traits of P. corethrurus. However, over the past decade, the abundance, biomass, and carbon (C), N, and P concentrations in the tissues of P. corethrurus have increased. A strong positive correlation between P. corethrurus population size and soil gram-negative (G−) bacteria biomass was observed, suggesting that P. corethrurus may benefit from the soil bacterial channel. This study ascertained that non-natural tropical lands may be resistant to N and P deposition in terms of earthworm related belowground processes, which would be helpful for fully understanding plant-soil biota feedback and their contributions to tropical plantation development and the mitigation of global climate change.

Seasonal dynamics of agricultural land use impacts on earthworm communities: Insights into diversity, abundance, and functional composition

Earthworms play a key role as soil bioengineers, but livestock farming and croplands can impact on the composition, structure, and functioning of earthworm communities. This study aimed to quantify the effects of replacing natural grasslands with crop rotations on the seasonal dynamics of key attributes of earthworm communities and explore soil physicochemical properties as mechanisms behind these effects. We conducted paired samplings on seven sites across Uruguay, comparing earthworm communities in soils under grazed natural grasslands and adjacent croplands, considering earthworm species composition, richness, diversity, and evenness, biomass, density, and mean body weight, over five consecutive seasons. Results revealed a clear negative impact of croplands on earthworm communities, showing substantial reductions in all considered attributes. Observed changes were attributed to environmental filters limiting the occurrence of larger exotic earthworm species in croplands, and variations in soil physicochemical properties were identified as potentially mediating some of these effects, including soil water regime (particularly affecting juvenile individuals) and soil organic matter content. These impacts resulted in a shift to dominance of r strategists (smaller, surface-feeding species such as Microscolex spp. in croplands compared to larger deeper-burrowing species in grasslands) and reduced functional composition of earthworm communities. Furthermore, seasonal dynamics revealed that differences between land uses were more pronounced during wetter periods, underscoring the relevance of seasonal variations when evaluating land use impacts on earthworm communities. Earthworms mean body weight resulted a useful attribute to be included in earthworm's assessments, allowing to identify impacts in community functional composition and suggesting size dependent mechanisms. Additional research is required to comprehensively understand the mechanisms behind these patterns and to develop more sustainable agricultural practices by considering soil fauna.

Organic residue valorization for Ethiopian agriculture through vermicomposting with native (Eudrilus eugeniae) and exotic (Eisenia fetida and Eisenia andrei) earthworms

Vermicomposting has recently been shown to be an efficient recycling technology that would improve the quality of the final product by stimulating the microbial community. However, the efficacy of vermicomposting process, as well as the microbial biomass and community structure during this bioconversion process, depend on earthworm species and type of substrate ingested. Therefore, this study investigated the potential of native (Eudrilus eugeniae) and exotic (Eisenia fetida and Eisenia andrei) earthworms in Ethiopia on nutrient transformation and microbial dynamics and enzymatic activity during vermicomposting of substrates from mixed agricultural wastes. Earthworm inoculation transformed the wastes into a nutrient-rich humified vermicompost with a significant reduction in pH, TOC and C:N ratios (twofold reduction compared to non-composted substrates). An increase in worm growth and cocoon production were shown in substrates of cow manure mixed with soybean and banana residues (CM + SB) after gut transit through Eudrilus eugeniae and Eisenia fetida. Cow manure mixed with maize and soybean residues (CM + MS) were found suitable for Eisenia andrei. The same substrate and earthworm species resulted in the highest nutrient concentrations (N, P, K, and S) and higher C loss (up to 77% of the initial C) with lower N loss (<9%) compared to non-composted substrates. A considerable increase in microbial biomass, β-glucosidase and dehydrogenase activity (two times more than control) was obtained in substrates of CM + SB using Eudrilus eugeniae. The PLFA analysis indicated that earthworms increased Gram-positive and Gram-negative bacteria, actinomycetes, AMF, fungi18:1, and protozoan population, while they reduced fungal community (fungi18:2 and fungi18:3) compared to uninoculated control. In conclusion, vermicomposting earthworms could potentially valorize substrates from agricultural wastes into nutrient-rich and microbially improved vermicomposts.

Earthworms enhance the bioremediation of tris(2-butoxyethyl) phosphate-contaminated soil by releasing degrading microbes

The escalating awareness of the environmental risks posed by organophosphorus flame retardants (OPFRs), e.g., tris(2-butoxyethyl) phosphate (TBOEP), necessitates the development of effective approaches to mitigate their adverse ecological effects. However, research on the remediation of OPFR-contaminated soil remains limited. In this study, a strategy is proposed to enhance the microbial remediation of TBOEP-contaminated soil through the introduction of exotic earthworms (Eisenia fetida). The presence of earthworms led to a substantial increase in the 28-d removal rates of TBOEP at concentrations of 0.05, 0.5, and 5 mg/kg, with improvements of 32.3 ± 2.0%, 33.2 ± 1.3%, and 33.0 ± 5.6% compared to rates in the absence of earthworms, respectively. The underlying mechanisms for this enhancement include the earthworm-mediated enrichment of TBOEP-degrading bacteria, particularly Rhodococcus, Flavobacterium, and Pseudomonas, and the transfer of Rhodococcus from the earthworm gut to the soil, resulting in an increased relative abundance within the soil. Concurrently, the earthworms stimulated soil peroxidase activity, facilitating the oxidative degradation of TBOEP. Furthermore, the rise in dissolved organic matter content following earthworm treatment fostered the growth of degrading bacteria in the soil. Rhodococcus emerged as a dominant contributor to soil TBOEP removal, consuming humic-like compounds in dissolved organic matter. This investigation underscores the significance of gut microbes and offers valuable insights for the application of earthworm-based remediation strategies in OPFR-contaminated soil.

Effects of Exotic and Native Earthworms on Soil Micro-Decomposers in a Subtropical Forest: A Field Mesocosm Experiment

Biological invasion is one of the most important factors affecting global biodiversity change, which can adversely affect ecosystem function. However, little is known about the effects of belowground biological invasions on soil ecosystems. In this study, we conducted a field-based mesocosm experiment to observe the effects of exotic and native earthworms (Pontoscolex corethrurus and Amynthas corticis, respectively) on soil nutrients and micro-decomposers (i.e., soil microorganisms and nematodes) in a subtropical forest in southern China. We found that exotic and native earthworms had different effects on nutrient availability and nematode communities in the soil. Specifically, exotic earthworms significantly decreased the content of nitrates in the soil and tended to decrease the total nematode abundance compared with native earthworms. Furthermore, nematode species richness and Shannon–Wiener index were lowest in the treatment with exotic earthworms and were the highest in the treatment with native earthworms. However, neither native nor exotic earthworms significantly affected soil microbial community composition. The results of redundancy analysis indicated that available phosphorus was positively correlated with nematode community. Our results demonstrated that exotic earthworms had adverse effects on the available nutrient content in the soil, and had a potential negative effect on the abundance of soil microfauna. These findings will be helpful in understanding the influence of exotic earthworms on soil micro-decomposers and the ecological consequences of earthworm invasion.

Are exotic earthworms threatening soil biodiversity in the Brazilian Atlantic Forest?

Invasive earthworms are threatening soil biodiversity and ecosystem functioning in formerly earthworm-free boreal and temperate forests. Although exotic earthworms are also found in tropical forests, they have received less attention from soil scientists. Here, we summarize data on earthworm populations in the native Brazilian Atlantic Forest (one of the world's 25 biodiversity hotspots) and present a case study on three forests at different regeneration stages, aiming to identify the patterns of exotic species distribution and also the possible consequences of invasive earthworms for soil ecosystem services and macrofauna communities. We found that exotic earthworms, mainly Pontoscolex corethrurus and pheretimoid species (Amynthas corticis and A. gracilis), dominated the earthworm fauna in the native Brazilian Atlantic Forest, while native earthworms were less abundant. Furthermore, we observed that exotic earthworms are probably threatening soil macroinvertebrates, especially detritivores and predators, due to the high soil bioturbation. The widespread occurrence of invasive earthworms in this biome raises concern regarding possible competition with the native soil fauna, including native earthworms, which could dramatically impact ecosystem services linked to soil, especially those related to climate regulation and water storage.

Invasive earthworms alter forest soil microbiomes and nitrogen cycling

Northern hardwood forests in formerly glaciated areas had been free of earthworms until exotic European earthworms were introduced by human activities. The invasion of exotic earthworms is known to dramatically alter soil physical, geochemical, and biological properties, but its impacts on soil microbiomes are still unclear. Here we show that the invasive earthworms alter soil microbiomes and ecosystem functioning, especially for nitrogen cycling. We collected soil samples at different depths from three sites across an active earthworm invasion chronosequence in a hardwood forest in Minnesota, USA. We analyzed the structures and the functional potentials of the soil microbiomes by using amplicon sequencing, high-throughput nitrogen cycle gene quantification (NiCE chip), and shotgun metagenomics. Both the levels of earthworm invasion and soil depth influenced the microbiome structures and the functional gene abundances. In the most recently and minimally invaded soils, Nitrososphaera and Nitrospira as well as the genes related to nitrification were more abundant than in the heavily invaded soils. By contrast, genes related to denitrification and nitrogen fixation were more abundant in the heavily invaded than the minimally invaded soils at various depths. Since denitrification can cause a nitrogen loss from the ecosystem, our results suggest the invasion of earthworms could influence the overall forest N cycling.

Agroecology niche for New Zealand's native earthworms

Exotic lumbricid earthworms have had some limited success colonising productive agricultural pastures in New Zealand, in place of native megascolecid species that did not adapt to the conversion from native vegetation cover. Native earthworms in lowland intensively-farmed landscapes are now almost entirely restricted to small fragments of native vegetation on marginal land where they coexist with adventive lumbricids. In recent years, regular pasture replacement using cultivation has been largely replaced by herbicide spray-out followed by direct drilling; much less soil disturbance potentially creates a new opportunity for native earthworms to colonise pastures. Reclaiming native earthworm habitat is critical not only to protecting diversity, but also to sustaining New Zealand's unique soil ecosystem services strongly associated to role of native species; however, there have been no studies related to this. Using a mesocosm experiment, we investigated how native and exotic earthworms modify physicochemical properties of a sheep-grazed pasture soil. The pasture soil was found to be equally suitable for the growth and survival of native and exotic species. Most burrowing earthworms increased the more soluble forms of macronutrients (N, P, S, K and Mg), but differences between native and exotic species were found to be larger than between functional groups. Two species of native earthworms, Octochaetus multiporus and Maoridrilus transalpinus, modified some soil properties in similar way to exotic species, but had significantly different impacts on pH, mineralisation of nutrients, and plant availability of trace elements. Compared to control, plant available N (PAN) and S concentrations were higher by more than 100% and 40%, respectively, in soils with presence of burrowing activity of the two native earthworms. Future co-existence of communities of native and exotic earthworms in agricultural pastures appears realistic, and this would benefit conservation of native species as well as dairy production. Further research may also reveal additional and unique benefits to soil quality that could be attributable to this formerly unavailable niche for native earthworms.

The long-term effects of invasive earthworms on plant community composition and diversity in a hardwood forest in northern Minnesota.

Nonnative European earthworms are invading hardwood forests of the Chippewa National Forest, MN. While effects on plant communities at the leading edge of invasion have been studied, little is known about longer-term effects of invasive earthworms. We applied a model using historic O-horizon soil thickness and a chronosequence approach to classify 41 hardwood sites in the Chippewa National Forest as "long-term wormed" (wormed >2 decades), "short-term wormed" or "unwormed/lightly wormed." Graminoids, especially Carex pensylvanica, had the greatest mean percent cover in sites that had been wormed for over two decades. The families with the greatest negative change in mean percent cover after over two decades of earthworm invasion were Asteraceae, Violaceae, and Sapindaceae (specifically Acer species). Across all diversity metrics measured, long-term wormed sites had the lowest understory plant species diversity, short-term wormed sites had intermediate diversity, and unwormed/lightly wormed sites exhibited the highest diversity. Long-term wormed sites had the lowest mean species richness across all sample scales (1-1024 m2). The greatest within-group compositional dissimilarity occurred at sites that had been wormed for over two decades, suggesting that sites that had been wormed for over two decades have not reached a compositionally similar end-state "wormed" community type. Our study suggests that understory diversity will decrease as hardwood forest stands become wormed over time. While our results support other findings that exotic earthworm invasion is associated with lower understory plant diversity in hardwood forests, our study was the first to use space-for-time substitution to document the effects after multiple decades of earthworm invasion.

A review of exotic earthworm observations in the Canadian boreal forest and taiga zones

Over the past few decades there has been increasing concern that boreal forests could convert from a carbon sink to a carbon source, thus accentuating the effects of climate change. Although forest fires are generally regarded as mainly responsible for causing boreal forests to transition to a carbon source, other factors, such as the activity of exotic earthworm species, could also play an important role. Invasive and exotic species of earthworm can affect nutrient cycling, biodiversity, and forest dynamics. In this context, greater knowledge of the distribution of exotic species of earthworm could help researchers to understand the likely changes in the ecosystems that they have colonized. Herein, we report the results of an exhaustive literature review of the presence of exotic species of earthworm in the Canadian boreal forest and taiga zones. We identified 230 sectors containing 14 earthworm species (11 exotic, two native, and one putative native) in six provinces and three territories across Canada’s boreal forest and taiga zone. We also report 23 as-yet unpublished observations from the province of Quebec. We noted the presence of earthworms in environments (acid soils, harsh climate) that were historically considered inadequate for their survival. This suggests that the portion of Canada’s boreal forests suitable for the presence or colonization of exotic species of earthworm is larger than was previously believed. This study represents the first compilation of locations with exotic species of earthworm in this large northern area. Factors that could affect their distribution and potential effects on boreal ecosystems are also discussed. We also report that several earthworm species seem to be overcoming the previously assumed limitations of temperature and soil pH.

An eco‐friendly management of organic waste by using exotic earthworms: A case study of revenue generation in Gandhi Zoological Park

AbstractBefore the start of vermicomposting, the large quantity of organic waste generated in the zoo was sold to the public at the rate of Rs. 500 per truck amount Rs. 9500 annually. However, the large profusion of waste was frequently left within the zoo premises imparting an ugly and unhygienic environment for the zoo. To make the park more attractive, self‐sustained (sold high‐quality vermicompost) and keep premises clean, a vermicomposting process was set up on a pilot basis. Vermicomposting of organic waste could have dual beneficial effects by generating an economically viable animal feed protein in the form of worm biomass while alleviating the negative effects of poor organic waste management. The aim of the study was the management of different organic wastes generated in the zoo by using exotic worms and makes the premises financially‐self dependent. The most dung‐producing animals in the zoo are herbivores and droppings of exotic birds are also included, on average below 200 kg or more waste is collected every week in the zoo. Analysis of different physico‐chemical properties of zoo vermicompost showed vermidegraded organic waste is a nutrient rich and eco‐friendly approach. Data were analyzed by using mean ± error.

Qualitative Study of Organic Fertilizer of Agrowaste (Cumin Straw) Plus Cow dung Using Earthworm Species Eisenia fetida and Perionyx sansibaricus

The present study is incorporated with agrowaste management and biofertilizer production in tropical India. For this, an exotic earthworm species Eisenia fetida and a local species Perionyx sansibaricus were used to decompose cumin straw and cow dung and evaluated vermicomposting efficacy. Physicochemical parameters of the vermibed such as pH, electrical conductivity, water holding capacity, organic carbon, C/N ratio, total nitrogen, phosphorus and potassium were evaluated in the vermicompost. The values of all the above physicochemical parameters of E. fetida worked bedding material varied significantly (PPerionyx sansibaricus also varied significantly (PE. fetida was better than P. sansibaricus for cumin plus cow dung bedding. Though E. fetida is better agrowaste converter but both the earthworm species may be used for organic waste management in desert region. It may provide the support in the form of biofertilizer to enhance the organic farming in region of the Thar Desert.

Relationship between earthworm abundance, ecological diversity and soil function in pastures

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.

Earthworm diversity and density as affected by soil and climatic factors in Raymond Mhlaba municipality, Eastern Cape province, South Africa

Earthworms play a key role in improving soil health, and their diversity and density are mainly affected by soil and climatic factors. This study determined the effects of rainfall, temperature and selected soil properties on the diversity and density of earthworms in Raymond Mhlaba municipality of the Eastern Cape, South Africa. Nine sites in the municipality covering the humid, sub-humid, semi-arid and arid regions were sampled. At each site, earthworms were collected for identification and quantification. The relationships between earthworm density and diversity against the selected factors were analysed using analysis of variance and Pearson correlations. Seven exotic earthworm species were identified, namely: Dendrobaena octaedra; (epigeic groups); Aporrectodea caliginosa; Pontoscolex corethrurus (Rhinodrillidae); Allolobophora chlorotica (endogeic groups); Amynthas aspergillum, Lumbricus terrestris and Fimoscolex sporadochaetus (anecic groups). No indigenous earthworms were found. There were significant differences in earthworm density and biomass across all the climatic zones (p < 0.05). Earthworm density and biomass showed positive correlations with soil moisture and rainfall but strong negative correlations with temperature (p < 0.05). Earthworm densities across all sites were lower than the global average. The study concluded that sub-humid environments exhibited the highest earthworm diversity and density while rainfall, temperature and soil moisture influenced earthworm distribution, diversity and density.

Effects of earthworms and warming on tree seedling growth: a small-scale microcosm experiment

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.

First Record of Exotic &lt;I&gt;Dichogaster saliens&lt;/I&gt; (Beddard, 1893) and &lt;I&gt;Metaphire posthuma&lt;/I&gt; (Vaillant, 1868) (Annelida: Clitellata) from Kerala State, Southern India

Among the 102 species of earthworms known from Kerala, Dichogaster saliens (Beddard, 1893) of the Family Benhamiidae and Metaphire posthuma (Vaillant, 1868) of the Family Megascolecidae were not recorded till date. The presence of exotic earthworms D. saliens and M. posthuma are documented herewith for the first time from Kerala, based on specimens collected from Ernakulam, Palakkad and Wayanad districts. Their descriptive account and distribution is provided.

Earthworms accelerate the biogeochemical cycling of potentially toxic elements: Results of a meta-analysis

Earthworms are ecosystem engineers, capable of modifying the soil environment they inhabit. Recent evidence indicates that they increase the mobility and availability of potentially toxic elements in soils, but a quantitative synthesis of the evidence required to understand mechanisms and identify soils most susceptible to earthworm-induced potentially toxic element mobilisation is lacking. We undertook a meta-analysis of 42 peer reviewed journal studies, comprising 1185 pairwise comparisons between earthworm-inhabited and earthworm-free soils to quantify the impact of earthworms on potentially toxic element mobility in bulk earthworm-inhabited soil and earthworm casts, and on plant uptake and concentration. We find that endogeic and epigeic earthworms increase the mobility of potentially toxic elements in the bulk soil, and earthworms from all ecological groups mobilise potentially toxic elements during passage of soil through the earthworm gut. We also observe an increase in the concentration and uptake of potentially toxic elements by plants growing on soils inhabited by epigeic (mostly Eisenia fetida) earthworms. Earthworms mobilise potentially toxic elements in geogenic soils to a greater extent than anthropogenically contaminated soils. Soils with very low (<2%) soil organic matter content are most susceptible to earthworm-induced potentially toxic element mobilisation. These findings have important implications for the ability of exotic earthworms to alter soil biogeochemical cycles when introduced to new environments. Mixing amendments with contaminated soils with the intention of reducing the mobility of potentially toxic elements may be aided by the activity of earthworms that accelerate the mixing processes. Furthermore, our findings also highlight a promising phenomenon that, if harnessed, may help to alleviate micronutrient deficiencies in degraded soils.

Molecular evidence reveals introduced populations of Eiseniella tetraedra (Savigny, 1826) (Annelida, Lumbricidae) with European origins from protected freshwater ecosystems of the southern Alborz Mountains

The presence of exotic earthworms has recently become a major concern and drawn significant attention to their potential effects on ecosystems and native invertebrate fauna. Although the occurrence of invasive annelids has been well recorded, their settlement in Iran is poorly documented. To investigate the biodiversity of aquatic Oligochaeta and to assess the presence of possible exotic species, DNA barcoding using the mitochondrial cytochrome c oxidase subunit 1 (COI) gene was conducted in two major protected rivers (Jajroud, Karaj) of the southern Alborz Mountains. As a result, new lineages of Tubifex, Haplotaxis and Lumbriculus were identified from Iran. Moreover, a semiaquatic lumbricid species, Eiseniella tetraedra, was unexpectedly found to be the most abundant species. The analyses showed the presence of six divergent lineages of E. tetraedra occurring in individual rivers. The presence of identical haplotypes shared between European, North American, Australian and Iranian localities, the sympatric accumulation of several distinct intraspecific lineages in the same rivers and the lack of a phylogeographic pattern reinforce the hypothesis of a possible inadvertent anthropogenic introduction. The relative abundance of lineages indicates a significant decline in the abundance of native oligochaetes, which may be linked to the preponderance of recently introduced European populations of E. tetraedra, probably mediated through human activities.