Aquatic Oligochaetes Research Articles

Influence of some environmental variables on the diversity and distribution of aquatic oligochaetes (Clitellata: Annelida) in the Nyong estuary (Atlantic coast, southern Cameroon)

Tropical estuarine ecosystems are subject to strong anthropogenic pressures, with the direct consequence of declining or lost biodiversity. An essential and little-known biological component of these estuarine ecosystems is the population of oligochaete annelids, which play an indispensable role in energy transfer and the biodegradation of organic and chemical compounds. This study sheds light on the diversity and structure of oligochaetes in the Nyong estuary under the influence of some abiotic parameters. Based on hydrobiological standard techniques, 1016 individuals grouped into 3 orders (Tubificida, Haplotaxida and Lumbriculida), 5 families (Naididae, Tubificidae, Haplotaxidae, Glossoscolecidae and Lumbriculidae) and 5 species were collected and identified. Alma nilotica, positively correlated with dissolved oxygen (P = 0.033; n = 72), was the most abundant species (464 individuals), followed by Tubifex tubifex (216 individuals), positively correlated with salinity (P = 0.029; n = 72), pH (P = 0.037; n = 72) and temperature (P = 0.044; n = 72) Limnodrilus hoffmeisteri and Rhynchemis sp. showed no particular affinity with the abiotic component considered in this study. The Shannon-Weaver's (H') and Pielou's evenness (J) indices coupled with the species richness of all surveyed stations (S1 to S12) showed a greater diversity of taxa only at station S12, located in the lower estuary, 1 km from the mouth; during the dry season. This study shows that the spatial dynamics of oligochaetes in the Nyong estuary are strongly influenced by abiotic parameters and seasonal cycles.

Toxicogenomics of the Freshwater Oligochaete, Tubifex tubifex (Annelida, Clitellata), in Acute Water-Only Exposure to Arsenic.

A toxicogenomic approach was used for toxicity evaluation of arsenic in the aquatic environment, and differential gene expression was investigated from 24 h and 96 h water-only acute toxicity tests with the aquatic oligochaete, Tubifex tubifex (Annelida, Clitellata). Several toxicological endpoints (survival and autotomy) of the oligochaete and tissue residues were measured, and dose-response modelling of gene expression data was studied. A reference transcriptome of the aquatic oligochaete, T. tubifex, was reconstructed for the first time, and genes related to cell stress response (Hsc70, Hsp10, Hsp60, and Hsp83), energy metabolism (COX1), oxidative stress (Cat, GSR, and MnSOD), and the genes involved in the homeostasis of organisms (CaM, RpS13, and UBE2) were identified and characterised. The potential use of the genes identified for risk assessment in freshwater ecosystems as early biomarkers of arsenic toxicity is discussed.

Analyzing retraction responses of Tubifex tubifex (Oligochaeta: Naididae) colonies to copper treatments through a digital image analysis approach for developing early biological warning systems.

Biological monitoring and assessments are commonly used for sustainable ecosystem management. Oligochaetes are found in various freshwater ecosystems and have been used as indicators of water quality and for the biological assessment of aquatic ecosystems. Among aquatic oligochaetes, the sludge worm Tubifex tubifex (Oligochaeta, Naididae) is tolerant to organic pollution and has been used as a biomonitoring indicator of toxicity and organic pollution. In this study, we investigated the response of worm colonies to copper (CuSO4) treatments (0.01, 0.05, 0.1, 0.5, and 1.0mg/L) in an observation cage (100mL beaker) for 30min. Using a digital image analysis approach, we measured the changes in the colony image area between pre- and post-copper treatment. After copper treatment, the colony image area tended to decrease, even at low copper concentrations. In addition, the colony areas did not recover to their original levels at high concentrations, although those at low concentrations did. Area decreased proportional to the logarithm of the copper concentration. Finally, our results present the possible use of the retraction responses of Tubifex tubifex colonies to chemical disturbances as early biological warning systems.

Effects of Environmental Factors on the Distribution and Diversity of Aquatic Oligochaetes

The aim of our study was to detect the actual distribution of oligochaete species and to identify their ecological differentiation with respect to environmental factors: altitude, temperature, oxygen concentration, conductivity, total organic carbon, and waterbody type. Although widespread, differentiation of oligochaete communities in four waterbody types and altitudinal groups can be observed through alpha and beta diversity. Their differences were analyzed using MANOVA, while the ecological preferences of species were presented with logistic Gaussian regression analyses. The highest number of the species of Oligochaeta was recorded in oligochaete communities in medium and large rivers. Total beta diversity decreased with the decreasing of waterbody size, the increasing of size of the substrate particles, river flow velocity, as well as altitude. Communities from small mountain rivers and streams and large and medium rivers with coarser substrate differed from other oligochaete communities. When coarser substrate was prevalent in smaller and medium rivers, a domination of a certain family was observed: Lumbriculidae (>800 m a.s.l.), Propappidae and Enchytraeidae (500–800 m), and Naididae (<500 m a.s.l.). Common species of Oligochaeta, with significantly overlapping ranges in running waters in Serbia, still show a clear grouping with respect to preference for certain types of waterbodies.

Collecting-Gathering Biophysics of the Blackworm Lumbriculus variegatus.

Many organisms exhibit collecting and gathering behaviors as a foraging and survival method. Benthic macroinvertebrates are classified as collector-gatherers due to their collection of particulate matter. Among these, the aquatic oligochaete Lumbriculus variegatus (California blackworms) demonstrates the ability to ingest both organic and inorganic materials, including microplastics. However, earlier studies have only qualitatively described their collecting behaviors for such materials. The mechanism by which blackworms consolidate discrete particles into a larger clump remains unexplored quantitatively. In this study, we analyze a group of blackworms in a large arena with an aqueous algae solution (organic particles) and find that their relative collecting efficiency is proportional to population size. We found that doubling the population size (N = 25-N = 50) results in a decrease in time to reach consolidation by more than half. Microscopic examination of individual blackworms reveals that both algae and microplastics physically adhere to the worm's body and form clumps due to external mucus secretions by the worms. Our observations also indicate that this clumping behavior reduces the worm's exploration of its environment, possibly due to thigmotaxis. To validate these observed biophysical mechanisms, we create an active polymer model of a worm moving in a field of particulate debris. We simulate its adhesive nature by implementing a short-range attraction between the worm and the nearest surrounding particles. Our findings indicate an increase in gathering efficiency when we add an attractive force between particles, simulating the worm's mucosal secretions. Our work provides a detailed understanding of the complex mechanisms underlying the collecting-gathering behavior in L. variegatus, informing the design of bioinspired synthetic collector systems, and advances our understanding of the ecological impacts of microplastics on benthic invertebrates.

An Annotated Checklist of the Main Representatives of Meiobenthos from Inland Water Bodies of Central and Southern Vietnam—II—Annelid Worms (Oligochaeta and Aeolosomatidae)

This work continues a series of publications on the diversity of the main groups of invertebrates found through the investigation of meiobenthic communities in various inland waterbodies in central and southern Vietnam. Here, a checklist of oligochaetes and aeolosomatids (the annelid worms) discovered for the period 2010–2021 is presented, as well as data on the structure and abundance of their populations found in the country, ecology, local and global distribution, and, where necessary, taxonomic, morphological and other comments. In total, 71 representatives of the species and supra–species ranks from 3 families and 17 genera are listed. In total, 39 representatives were identified to the species level. During the present research, 2 species new to science were discovered and described in previously published works. This paper reports 9 more forms that need further study and may belong to still undescribed species. In addition to the new and still-unidentified species, the checklist reports about 30 more members of species and supra–species ranks that were recorded in Vietnam for the first time. Based on new and previously published data, the currently known diversity of aquatic oligochaetes and aeolosomatids in Vietnam is estimated at approximately 100–113 and 8–9 representatives, respectively. It is shown that members of the family Enchytraeidae remain practically unexplored in the waterbodies of the region. The subfamily Tubificinae and the family Aeolosomatidae also continue to be relatively poorly studied here at the species level.

Identification and Description of Aquatic Oligochaeta in Sanggau City Canal West Kalimantan

The canals in the center of Sanggau City, West Kalimantan serve as a medium for wastewater which enters the Kapuas River. The density of community activities in this city has caused indications of its canals being polluted by organic and inorganic materials. These contaminants enter the canal continuously, hence its accumulation can change the texture of the substrate/sediment which is the habitat for aquatic Oligochaete. The purpose of this study was to identify and describe the types of aquatic Oligochaete in the canals of Sanggau City. The research was conducted from August to September 2020 using the purposive sampling method at five stations, namely Tanjung Sekayam Village, Ilir Kota Village, Beringin Village, and Bunut Village, with three replications at each sampling station. The results showed that aquatic Oligochaete at the canals of Sanggau City consisted of 1 order, 1 family, 2 genera, and 3 species with a total of 1367 individuals. The identified species are Branchiura sowerbyi, Limnodrilus claparedeianus, and Limnodrilus hoffmeisteri.Keywords: Species Identification, Aquatic Oligochaeta, Sanggau City Canal

Molecular characterisation and histopathological study of Eustrongylides excisus nematode in the northern pike (Esox lucius)

Eustrongylides excisus is a parasitic nematode species whose life cycle requires two intermediate hosts, an aquatic oligochaete and a benthophagous fish. In the present study, 100 specimens of Esox lucius Linnaeus weighing 550-800 g were collected from Freidoonkenar, south of the Caspian Sea (Mazandaran province, Iran) and were examined for the presence of Eustrongylides. The bright red nematode larvae were found in the testes and encapsulated in the body musculature of 90% of E. lucius fish. The larvae were diagnosed as Eustrongylides excisus. Tissue samples were collected from the muscles and testes for histopathological examination of the lesions caused by the parasitic larvae. For molecular analysis, the nematode larvae genomic DNA was extracted and molecular characterisation of Eustrongylides and comparison with the corresponding sequences available in the GenBank was done. The histopathological damages caused by parasites in the muscle included external nodules, inflammation, necrosis, and granulomas. Granulomas containing multi-nucleated giant cells, epithelioid cells, lymphoid cells, macrophages and necrotic debris were observed. Microscopic examination of the testes revealed mild vacuolar degeneration in some Sertoli cells. Molecular analysis confirmed obtained larvae as E. excisus. Comparison of DNA sequences showed that isolated nematodes were very similar to those obtained from freshwater fish in China. The present study reported Eustrongylides nematodes in Esox lucius, and inflammatory lesions caused by E. excisus larvae in the muscle and testis of this species of fish for the first time. In addition, molecular characterization and phylogenic analysis of recovered larvae showed presence of microvarients.

A Study of Some Aquatic Oligochaetes Community in Shatt Al-Hillah/ Middle of Iraq

The current study discusses the spatial distribution of Oligochaete communities on Shatt Al-Hillah. Monthly samples of Oligochaete worms were gathered from four locations along the Shatt Al-Hillah in the middle of Iraq, between September 2019 and May 2020. show the study for the existence of521Individual aquatic Oligochaeta belong to 7 species from the Naididae and Lumriculdae subfamilies, as well as the Pristinae subfamily, and in Site S3 had the largest number of worms, with 180 worms from 7 species being detected, while in Site S2 had the least number of worms, 107 from 5 species. The largest individual numbers were registered in February, while the lowest were recorded in April. The species, Prisma aequiseta, was first recorded, in the Shatt Al-Hillah rive. Show tubificid worms, Branchuira sowerbyi, and Limnodrilus hoffmeisteri were the most abundant species in the Shatt Al-Hillah.

First record of the complete mitochondrial genome of Tubifex tubifex (Müller) 1774 (Annelida; Clitellata; Oligochaeta) and phylogenetic analysis

The complete mitochondrial genome of Tubifex tubifex was analyzed using the MGISEQ-2000 platform. The size of the complete mitochondrial genome was 15,972 bp. Data pertaining to the genome, such as the presence of 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes, and a putative control region were submitted to NCBI (MW690579). A phylogenetic tree was constructed with the sequences of the 13 PCGs using the maximum-likelihood method. Despite only a few references available on the complete mitochondrial genome of other aquatic oligochaetes, our phylogenetic analysis revealed that the freshwater oligochaetes T. tubifex and Limnodrilus hoffmeisteri are in a cluster different from that of the earthworm group.

A new record of three tubificid species (Annelida: Oligochaeta) from Al-Hawiezah marsh, Iraq

This paper reports the first record of three species of aquatic oligochaete worms from Al-Hawiezah marsh, south of Iraq. It was evident that the specimens belonged to the family: Naididae, subfamily: Tubificinae, Species: Aulodrilus pigeuti; Embolocephalus velutinus and Limnodrilus profundicola. A. pigueti is a new record for Iraqi fauna. The study includes the identification and description of these species together with photographic illustrations of chaetal types of each species.
 

The influence of leaf litter on the distribution of aquatic oligochaetes in the Tunca River (Edirne, Turkey)

The influence of leaf litter on the distribution of aquatic oligochaetes in the Tunca River (Edirne, Turkey)

Integrated transcriptomic and metabolomic analyses reveal mechanism underlying higher resistance of the marine oligochaete Thalassodrilides cf. briani (Clitellata: Naididae) to heavy contamination of sediments with polycyclic aromatic hydrocarbons

In some coastal areas, sediments are contaminated with various chemical compounds, causing significant threats to marine organisms. Therefore, the development of remediation techniques is important. Here, we focused on bioremediation using marine benthic animals such as aquatic oligochaetes. The oligochaete Thalassodrilides cf. briani is highly resistant to contamination of sediments with toxic chemicals. We examined whether T. cf. briani could decompose high-concentration polycyclic aromatic hydrocarbons (PAHs) in sediments. Furthermore, relevant genes expressed in T. cf. briani exposed to contaminated sediment were comprehensively examined using next-generation sequencing, and its metabolites were identified by metabolomic analysis using gas chromatography–mass spectrometry. T. cf. briani reduced the concentration of 16 PAHs in the sediment from 55,900 to 45,200 ng/g dry weight in 50 days, thereby reducing total PAH concentrations by approximately 20%. The results of transcriptomic analysis suggest that activation of a drug-metabolizing enzyme system may promote the metabolism of harmful chemical substances during excretion of chemicals from the body. According to the results of principal component analysis based on the values of 43 types of metabolomes identified by metabolomic analysis, groups were divided according to the difference in the number of exposure days. In addition, levels of glutamine, which is important for maintaining digestive tract functions, increased. This suggests that the digestive tract function promotes the metabolism and detoxification of foreign substances. Furthermore, transcriptome analysis revealed that glutamate dehydrogenase increased 1.3-fold and glutamine synthetase increased 1.7-fold, confirming the increase in glutamine. Thus, we conclude that T. cf. briani adapted to the polluted sediment by regulating its metabolism.

Ovary micromorphology and oogenesis in a rhyacodriline oligochaete (Clitellata: Naididae, Rhyacodrilinae).

The main goal of the article is to describe the ovary organization and oogenesis in Peristodrilus montanus, an aquatic oligochaete of the subfamily Rhyacodrilinae. The presented analysis will not only enrich the knowledge about how eggs are formed but, because of the suggested conservatism of ovary organization in clitellate annelids, can contribute to disentangling the complex phylogenetic relationships of the rhyacodrilines within Naididae. The paired, conically shaped ovaries are located in segment XI. They are composed of a dozen or so syncytial germ-line cysts, which are associated with somatic cells. Each germ cell in a cyst has one intercellular bridge that joins it to a central and anuclear cytoplasmic mass, the cytophore. This pattern of cyst organization is typical for all clitellates that have been studied to date. Initially, the germ cells in a cyst undergo a synchronous development, however, there is no synchrony between cysts, and therefore there is a developmental gradient (oogonia, pre-diplotene germ cells, germ cells in diplotene) of oogenesis along the long ovary axis. The cysts are composed of a maximum of 32 cells. Cysts with cells in diplotene detach from the ovaries and the extraovarian phase of oogenesis begins. The developmental synchrony is lost, one cell (an oocyte) per cyst starts to gather cell components and yolk and grows considerably. The remaining cells grow to some extent and function as nurse cells. Like in other microdriles, P. montanus oocytes are rich in yolk; other features of oogenesis are also similar to those that are known from other microdrile taxa. The system of ovary organization found in the studied species is broadly similar to the corresponding features known from Naidinae and Phreodrilidae and, to some extent, in Enchytraeidae. However, this system is different from the one that is known in Tubificinae, Limnodriloidinae and Branchiurinae.

Environmental or spatial components? Patterns that structure the assemblages of aquatic oligochaetes in Argentine Pampas streams

AbstractThe metacommunity theory includes processes that contribute, at different scales, to the understanding of the distribution of organisms in space and aims to assess the relative importance of spatial and environmental factors in the structuring of communities. Fluvial ecosystems of the Argentine Pampas are characterized by their environmental heterogeneity from slow water courses and variable development of aquatic vegetation to faster courses. They are affected by the different land uses, which are among the main threats to biodiversity and alter the dispersal of the species. Forty‐four species of aquatic oligochaete assemblages from 15 streams of nine Pampean basins were seasonally analyzed. The assemblages were characterized through estimations of taxonomic richness, α and β diversity. No differences were found in the assemblages of the substrates (sediments and aquatic vegetation) within each stream, except for Juan Blanco stream. However, differences were found between streams, as well as between basins. The oligochaetes that contributed most to the dissimilarity among streams and basins were Nais communis, Limnodrilus hoffmeisteri, Dero obtusa, and Stylaria fossularis. Two groups of sites were identified through the analysis of canonical correspondence: those of mountain basins and those of lowland basins. The variance partitioning showed that local environmental conditions (acting as environmental filters) accounted for 15.64% in the ordering of the assemblages, while 14.60% was explained by altitude and geographic factors (as a dispersal limitation). These results help to understand the processes that organize the distribution of organisms at different scales, which could have important implications when making decisions regarding biomonitoring and conservation.

The complete mitochondrial genome of Nais communis Piguet, 1906 (Annelida; Clitellata; Naididae)

The complete mitochondrial genome of Nais communis was analyzed using the Illumina Hiseq 2000 platform. The length of the complete mitochondrial genome was 15,685 bp, and the data were submitted to NCBI (MW770354). The genome contained 13 protein-coding genes (PCGs), 2 rRNA genes, 22 tRNA genes, and a putative control region. A phylogenetic tree was constructed based on the sequences of 13 PCGs identified by the maximum-likelihood method. Regardless of the lack of studies on the complete mitochondrial genome of other aquatic oligochaetes, the phylogenetic tree showed N. communis to cluster with Tubifex tubifex and Limnodrilus hoffmeisteri with high support value, and the freshwater oligochaete and earthworm groups to be sister groups.

First record of the complete mitochondrial genome and phylogenetic analysis of Limnodrilus hoffmeisteri Claparède, 1862 (Annelida; Clitellata; Oligochaeta)

The complete mitochondrial genome of Limnodrilus hoffmeisteri was analyzed using the Illumina NovaSeq 6000 platform. The length of the complete mitochondrial genome was 15,972 bp. The sequencing data, comprising 13 protein coding genes (PCGs), 2 rRNA genes, 22 tRNA genes, and a putative control region, were submitted to the National Center for Biotechnology Information (MW732144). A phylogenetic tree was constructed based on the sequences of 13 PCGs using the maximum likelihood method. To date, only a single study has been conducted on the complete mitochondrial genome of another aquatic oligochaete. This phylogenetic tree revealed that L. hoffmeisteri is clustered with Tubifex tubifex and forms a sister group to the earthworm group.

Sediment Assessment of Al-Hindyia and Al-Abbasyia River / Iraq by aquatic oligocheata community as bioindicators

Bioindicators have an important role in assessing the quality of water bodies. Aquatic oligocheates, was used as a bioindicator to assess the sediment quality of Al-Hindyia and AL-Abbasyia river (branches of Euphrates River in Iraq). Two sites in each river have been chosen for this purpose, site S1 was located at Al-Hindyia River and S2 at Al-Abbasyia River. Some kinds of biological indices were used in this study, comprising the percentage of oligochaetes in benthic invertebrates, ranged from 20.3-60.16%. While the percentage of Tubificidae within benthic invertebrates was close 43.3-43.9%.Index of pollution D ranged from 0.13-0.21. The maximum percentage of aquatic oligochaetes to insects larvae of family Chironomidae larvae was recorded at S2 90% while at S1 60%. I0 was scored high value at S1 36.06 whilst only 30.56 at S2.E0 was A8 at S1 and A9 at S2.while IOBS was 15.26 at S2 and 7.07 at S1.The percentage of subfamily Tubificidae (TUSP) showed the highest value 21.21% at S1 while 11.79%at S2 .

DNA barcoding of Naididae (Annelida, Oligochaeta), based on cytochrome C oxidase gene and ITS2 region in China.

Exploring the effectiveness of DNA barcoding in species identification is a prerequisite for biodiversity conservation and environmental monitoring. Aquatic oligochaetes could serve as excellent indicators in aquatic monitoring programmes. However, few studies have examined the effectiveness of DNA barcoding in these specific organisms. The mitochondrial cytochrome C oxidase (COI) gene of 83 specimens belonging to 40 species of 18 genera were sequenced in this study. The results showed that there was a barcode gap between species of Naididae and the intraspecific genetic distances of each species were smaller than interspecific genetic distances. The classification results of ABGD (Automatic Barcode Gap Discovery) were consistent with those of morphological identification, except for Tubifextubifex and Lumbriculusvariegatus. All species were successfully distinguished in the phylogenetic tree, based on the ITS2 region, which was coincident with the morphological result. Our results provided evidence that DNA barcoding can be used as an effective and convenient tool for species identification of the family Naididae and even for other aquatic oligochaetes.

English

Despite their great interest for the integrated management of water resources, information on the ecology of aquatic oligochaetes is still sketchy in Cameroon. The present study aims at contributing to the knowledge on the distribution, microhabitat and life history of Naididae tubificids taxa in some eight water bodies of the city of Yaoundé. A total of 132 samples were analysed and the morphospecies Branchiura spp. and Limnodrilus spp. were identified. The most abundant species were Branchiura spp. with 2035 individuals versus 880 Limnodrilus spp. Both of them demonstrate low seasonal variations. It appeared that, these annelids are more abundant on clay-rich soils than on sand and the herbarium. Assessment of the organic pollution index indicates an organic pollution of the sampled waters ranging from moderate to high (3.67-2). The redundancy canonical analysis shows that Branchiura spp. are more present in saline waters revealing high organic pollution factors variables. During the study period, some 10 individuals of Limnodrilus spp. presented a shrunken tail. That reveals a strong environmental pressure due to the action of predators or the presence of heavy metals in the aquatic system evaluated. All these characteristics indicate a high pollution and predation pressure in the milieu.   Key words: Annelids oligochaete, ecology, bottom nature, polluted water.