Oligochaete Assemblages Research Articles

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.

Are hyporheic oligochaetes efficient indicators of hydrological exchanges in river bed sediment? A test in a semi‐natural and a regulated river

AbstractRiver‐groundwater exchanges are crucial for several ecological processes, but difficult to localize. Hyporheic oligochaetes may represent efficient biological indicators of these exchanges, but hydrological disturbance may alter oligochaete distribution and blur the spatial patterns of river‐groundwater exchanges. Oligochaete assemblages were compared in the Drôme River, which is a semi‐natural braided river with an unmodified discharge, and the Ain River, which has reduced sediment mobility and hydropeaking due to several upstream dams. In the semi‐natural river, the oligochaete distribution was mostly controlled by the origin of the water: some stygoxene species (e.g., Chaetogaster spp. and Vejdovskyella intermedia) were restricted to or more abundant in downwellings, whereas a set of stygophiles (e.g., Stylodrilus sp. and Cernovitoviella sp.) and stygobites (e.g., Aberrantidrilus cuspis) were present or more abundant only in upwellings. Species living in fine sediment (e.g., Potamothrix sp. and Tubifex sp.) also occurred in upwellings due to their location at the border of the braided strip. Conversely, in the regulated river, oligochaete assemblages were abundant and diversified, with species living in fine sediment being dominant in the partially clogged stations. The spatial distribution of most species did not follow typical surface‐hyporheic exchange patterns: most stygophiles (e.g., Proppapus volki and Marionina argentea) and some stygobites (e.g., Haber turquini) were found in both upwellings and downwellings or even at stations without water exchanges (e.g., Rhyacodrilus balmensis). In rivers subjected to hydrological disturbance and hydropeaking, oligochaetes became poor indicators of river‐groundwater exchanges.

Shaping of the aquatic oligochaete assemblages in inland saline anthropogenic habitats: a case study of coal mine settling ponds in southern Poland

Shaping of the aquatic oligochaete assemblages in inland saline anthropogenic habitats: a case study of coal mine settling ponds in southern Poland

Aquatic oligochaete fauna (Annelida, Clitellata) in Lake Tonle Sap and adjacent waters in Cambodia

In surveys conducted during 2000–2005, 39 taxa of aquatic oligochaetes belonging to the families Enchytraeidae and Naididae were found in Lake Tonle Sap in the Mekong River Basin, Cambodia. Dominated by naidines and pristinines (29 taxa), they mainly comprised widely distributed species as well as South Asian and Southeast Asian species. Among the four areas studied, the littoral regions of the lake—where inundated forests and aquatic vegetation developed during the flooded seasons—presented the highest number of species. Submerged vegetation in the littoral Lake Tonle Sap harbored abundant epiphytic oligochaetes, especially Stylaria fossularis. In contrast to the rich abundance of naidine and pristinine fauna, tubificines and ryhacodrilines were scarce in and around the lake, irrespective of the vegetation in their habitats. Several Aulodrilus species and Branchiura sowerbyi were the main representatives of the benthic oligochaete assemblages throughout the offshore zone of the lake without vegetation. It is noteworthy that the widely distributed tubificines Tubifex tubifex and Limnodrilus hoffmeisteri were not found in any surveyed locality.

Arthropod and oligochaete assemblages from grasslands of the southern Kenai Peninsula, Alaska.

BackgroundBy the end of this century, the potential climate-biome of the southern Kenai Peninsula is forecasted to change from transitional boreal forest to prairie and grasslands, a scenario that may already be playing out in the Caribou Hills region. Here, spruce (Picea × lutzii Little [glauca × sitchensis]) forests were heavily thinned by an outbreak of the spruce bark beetle (Dendroctonus rufipennis (Kirby, 1837)) and replaced by the native but invasive grass species, Calamagrostis canadensis (Michx.) P. Beauv. As part of a project designed to delimit and characterize potentially expanding grasslands in this region, we sought to characterize the arthropod and earthworm communities of these grasslands.We also used this sampling effort as a trial of applying high-throughput sequencing metabarcoding methods to a real-world inventory of terrestrial arthropods.New informationWe documented 131 occurrences of 67 native arthropod species at ten sites, characterizing the arthropod fauna of these grasslands as being dominated by Hemiptera (60% of total reads) and Diptera (38% of total reads). We found a single exotic earthworm species, Dendrobaena octaedra (Savigny, 1826), at 30% of sites and one unidentified enchytraeid at a single site. The utility of high-throughput sequencing metabarcoding as a tool for bioassessment of terrestrial arthropod assemblages was confirmed.

Groundwater oligochaetes (Annelida, Clitellata) from the Mercantour National Park (France), with the descriptions of one new genus and two new stygobiont species

ABSTRACT Although recognized as an outstanding hotspot of biodiversity for both flora and fauna, the Mercantour massif remains almost totally unexplored in terms of its groundwater fauna. This work presents the first overview of groundwater oligochaete assemblages of the Mercantour National Park after a standardized exploration of both consolidated (fractured massif) and unconsolidated (porous) aquifers. About 40 species of oligochaetes were found at 49 stations representative of the main hydrogeological basins of the Mercantour National Park, from both spring and hyporheic zone habitats. Five stygobiont species are identified, probably all new to science, of which two are formally described: Aberrantidrilus stephaniae Martin n. gen., n. sp. (Naididae Ehrenberg, 1828, Phallodrilinae Brinkhurst, 1971) and Marionina sambugarae Schmelz n. sp., a species belonging to the widespread Marionina argentea (Michaelsen, 1889) species complex (Enchytraeidae Vejdovský 1879). The freshwater subterranean species formerl...

If you’ve seen one worm, have you seen them all? Spatial, community, and genetic variability of tubificid communities in Montana

AbstractGenetic studies are recognized increasingly as important for understanding naturally occurring disease dynamics and are used to predict host genetic diversity and coevolutionary processes and to identify species composition in ecological communities. Tubifex tubifex, the definitive host of the whirling disease parasite Myxobolus cerebralis, comprises 6 known lineages that vary widely in parasite susceptibility. We used 16S ribosomal DNA (16S rDNA) to identify relationships among genetic variability of 3 oligochaete genera (T. tubifex, Rhyacodrilus spp., and Ilyodrilus spp.; Oligochaeta:Tubificidae), oligochaete assemblage composition, and the presence of whirling disease in 9 locations across 4 watersheds in Montana, USA. We assessed genetic variability among 183 tubificid worms from locations classified as positive or negative for whirling disease based on 5 to 8 y of monitoring by the Montana Department of Fish, Wildlife, and Parks. Within genera, we found 2 groups of T. tubifex (lineages I and ...

Diversity and distribution of oligochaetes in tropical forested streams, southeastern Brazil

The distribution and beta diversity of oligochaete assemblages were investigated in different spatial scales to verify the influence of environmental factors and geographic distance on their structure. Two types of mesohabitats (riffles and pools) were sampled in eight first-order streams located in four preservation areas (Poco D’Anta Municipal Biological Reserve, Santa Cândida Municipal Biological Reserve, Ibitipoca State Park and a private farm called Fazenda Floresta) and two Atlantic Forest phytophysiognomies (Seasonal Semideciduous Forest and Rocky Field). Variations in the taxon richness, abundance and composition of the oligochaete assemblages occurred between streams and phytophysiognomies, but not between riffles and pools in the same stream. Low beta diversity values were found and both turnover and nestedness contributed similarly in the environments studied, which could have occurred because of the high capability of oligochaetes to adapt to different environmental conditions. Although the canonical correspondence analysis explained 85.5% of the data (first three axes), the partial Mantel test showed greater influence of geographic distance on the faunal composition than the environmental variables measured. Simple linear regression confirmed this result and showed that the decay of similarity increased with distance between streams. The information from this study sheds light on how environmental and spatial factors determine the variation in the distribution and diversity of oligochaetes in forested low-order streams.

Oligochaete assemblages of Swiss Alpine lakes

The present paper describes the oligochaete assemblages of 12 Swiss Alpine lakes (1700–2500 m above sea level) in Canton Ticino. The lake catchment geology is dominated by gneiss. The scarcity of carbonate rocks leads to a low buffering capacity, increasing the lakes’ sensitivity to acidification. Because of their very low phosphorus concentrations, they are defined as ultraoligotrophic. Oligochaetes were identified from kick-samples taken from the outflow and littoral zone of the lakes one to three times per year in 1991–1994, 2003 and 2007, when the lake water chemistry was also characterized. Oligochaete assemblages consisted of 19 species in total, 18 of which were found in the littoral zone, and 10 in the outlets. Amongst them, Cernosvitoviella goodhui Healy, 1975 was recorded in Switzerland for the first time. Principal component analysis (PCA), performed excluding the highly alkaline Lake Bianco (pH = 7.8 and alkalinity = 566 µeq L−1) due to its atypical chemical composition, divided the remaining lakes into two groups with different sensitivity to acidity: the first group of four lakes was characterized by a higher average pH (6.4) and alkalinity (32 µeq L−1), whilst the second group of seven lakes was characterized by a lower average pH (5.7) and alkalinity (5 µeq L−1). Multivariate analysis performed on data collated from the littoral zone highlighted geo-lithology as a key driver in determining the species distribution among lakes. When applied to the lake outlet data, a similar distinction between acidic and calcareous waters was implied. Precipitation influenced the oligochaete assemblage in the littoral zone. During years with higher annual rainfall, the relative abundance of Enchytraeidae increased, probably because their semi-aquatic nature allows them to colonize the littoral zones that dry out periodically.

Use of oligochaete communities for assessing the quality of sediments in watercourses of the Geneva area (Switzerland) and Artois-Picardie basin (France): proposition of heavy metal toxicity thresholds

The aim of the study was to validate biological tools based on the analysis of sediment-dwelling oligochaete assemblages for assessing the biological quality of sediments in watercourses. The study intended to establish and compare heavy metal toxicity thresholds in streams of two different ecoregions (Geneva area in Switzerland and Artois-Picardie basin in France). The metals Cr, Ni, Cu, Zn, Hg, Pb, Cd, As, Co, Fe and Mn were analyzed. The PEC-Q (Probable Effect Concentration-Quotient) and TEC-Q (Threshold Effect Concentration-Quotient) were used as metal contamination indices. The results showed a significant negative correlation between the oligochaete index of sediment bioindication IOBS and metal contamination indices. Moreover a significant positive correlation between the percentage of Tubificinae without hair setae and metal contamination indices was noticed. Toxicity thresholds of PEC-Q=0.14–0.18 and TEC-Q=0.4–0.6 were established. The toxicity thresholds established in the two different ecoregions were consistent. At some sites, the sediment biological quality evidenced by the oligochaete analysis was poor, yet moderate PEC-Q were observed. The effects of confounding factors such as the bioavailability of metals and the presence of other pollutants (PCBs, PAHs and organic pollution) are discussed. Other conflicting results seemed to be explained by a reduced bioavailability of metals due to organic matter and Mn/Fe oxides.

Oligochaeta of the Danube River — a faunistical review

AbstractThe aim of this work is to discuss the distribution of Oligochaeta (Annelida) in the Danube River using the collections made by the Joint Danube Survey 2007 (JDS2) on more than 2800 km of the river. The basic faunistical features of the oligochaete assemblages were analysed with regard to three main sectors of the Danube (upper, middle and lower reaches, the last with the Danube Delta). A total of 52 oligochaete taxa have been recorded. Most of the observed species are typical of the potamon-type rivers in the region, and are well adapted to moderate-to-high organic load. The highest taxa richness and frequency of occurrence were observed among the Tubificidae family. Naididae, Propappidae, Enchytraeidae and Haplotaxidae had also low frequency. The upper reach of the Danube showed the lowest species richness, while the middle reach is characterised by its highest species richness. Construction of dams and regulation of the riverbed have resulted in an increase of limno(rheo)philic taxa which prefer slow-flowing and lentic zones.

Distribution of aquatic oligochaetes (Annelida, Clitellata) of high-elevation lakes in the Eastern Black Sea Range of Turkey

Many large and small lakes of varying depths are present in the Eastern Black Sea Range of Turkey, the nation's third most important glacial region following the Ağrı and Cilo-Sat mountain ranges. During the present study, 6 expeditions to collect aquatic oligochaetes from these lakes were conducted in July and August of 2005, 2006, and 2007; qualitative and quantitative samples were collected from 59 glacial lakes. We present and analyze the dominancy and distribution of aquatic oligochaete assemblages and their relation to environmental factors (temperature, dissolved oxygen, pH, electrical conductivity, salinity, turbidity, PO_4^{-3}-P, HCO_3^{-}, organic carbon, hardness, Ca^{2+}, Mg^{2+}, Si, water depth, and altitude) using classification and ordination techniques. Canonical correspondence analysis (CCA) was used to characterize the relationship between oligochaetes and the environmental variables. As a result, we determined the 4 most important environmental variables (elevation, water depth, dissolved oxygen, and temperature) affecting species distribution in general. Sampling localities were clustered into 8 groups with the unweighted pair-group method with arithmetic mean (UPGMA) based on physicochemical characteristics. The relationships between the total number of individuals and environmental measurements were determined by a simple analysis of variance (ANOVA) test. The results of our analyses suggest a significant positive correlation between altitude (P < 0.05; F = 2.994) and the total number of individuals.

Potential responses of oligochaetes (Annelida, Clitellata) to global changes: Experimental fertilization in a lowland stream of Argentina (South America)

One of the possible consequences of climatic change for streams and rivers in the pampean region of South America is an increment in nutrient loads. To analyze this possible perturbation on a biological scale, the response of oligochaetes to an experimental eutrophication of the La Choza Stream, Argentina was studied. We proposed that the addition of nutrients could increase the abundance, biomass, and species composition of the stream. Two stretches (Control and Treatment sites) were selected, with bimonthly samples being taken (March 2007 through February 2009) in two habitat types: the sediments and the aquatic vegetation. On each sampling occasion the environmental variables were measured. The nutrient addition consisted in the continuous dissolution of a commercial fertilizer. The oligochaete mean density and total biomass, the taxonomic richness, the Shannon diversity ( H ′), and the evenness ( E ) were calculated and the BACI ANOVA design used to compare the differences between the sites. Thirty-three species of the families Naididae (Naidinae, Pristininae, Tubificinae, and Rhyacodrilinae), Opistocystidae, Enchytraeidae plus Aphanoneura Aeolosomatidae were collected. The oligochaete abundance and biomass increased significantly in the sediments and on the aquatic vegetation, especially among the Naidinae and Pristininae during their asexual reproductive phase. The diversity and evenness varied significantly in the sediments with the nutrient addition. Significant differences in the species richness and diversity were found on the aquatic vegetation, with both increasing at the treatment site after the fertilization. A significant correlation (Spearman) was observed between the oligochaete density in the sediments and the NO 3 -N and NH 4 -N concentration in the water. The increment in the naidines resistant to the fertilizer throughout the experiment could be explained by the greater nutrient availability, their mode of reproduction, and their short life cycles. The results of our study suggested that the incorporation of nutrients modified the composition of the oligochaete assemblage in favor of herbivores and detrivores. The usefulness of these indicator organisms in monitoring freshwater systems is subsequently discussed.

Relationships between the spatial distribution of oligochaetes (Annelida, Clitellata) and environmental variables in a temperate estuary system of South America (Río de la Plata, Argentina)

The oligochaete assemblage on the Argentine coast of the Río de la Plata estuary was sampled seasonally within environments having different types of disturbances. Three habitats were sampled: sediments free of vegetation, sediments within bullrush stands and substrates with Limnoperna fortunei. The species richness, evenness and Shannon–Wiener diversity values were different among those habitats. The only dominant species (according to the Kownacki index) was Nais variabilis. Mean density values varied between 400 and 199,500 ind./m2. Organic matter, ammonium and phosphates correlated positively with the mean oligochaete abundance, but not with the granulometry. Physicochemical variables and nutrient levels were measured and their relation to the sampling sites assessed through a principal component analysis (41.8% cumulative variance). The canonical correspondence analysis (41.2% cumulative variance) indicated that the oligochaetes distributed along both a eutrophication–pollution gradient and a turbidity–conductivity gradient. These results would be useful for assessing the ecological status of estuaries for a subsequent implementation of appropriate sustainability-management policies.

Refinement of biomonitoring of urban water courses by combining descriptive and ecohydrological approaches

Two approaches are proposed for developing adapted metrics, proposing realistic and sustainable ecologic objectives, and suggesting a management strategy for stream rehabilitation. The first approach implemented a harmonization system of French standardized biotic indices. The second one was based on the development of functional traits (FTrs), which were defined by oligochaete assemblages inhabiting coarse surface sediments and the hyporheic system. The harmonization system allowed to define a weighted general ecological quality. The FTrs characterized an ecological potential (EP) resulting from interactions between physical factors (dynamics of hydrologic exchanges between surface water and groundwater) and chemical factors. An example of using both approaches at the same urbanized site is presented and serves for planning of rehabilitation activities. The benefits, drawbacks and progress of both approaches are discussed.

Using hydro-geomorphological typologies in functional ecology: Preliminary results in contrasted hydrosystems

The study highlights the relevance of integrating hydro-geomorphological typologies in pluri-disciplinary ecological researches on ecosystem functioning, in two contrasted hydrosystems: the Rhine alluvial plain and the Yzeron basin. Two hydro-geomorphological typologies of reference status in rivers, elaborated from the same conceptual scheme, are compared with two bio-typologies of ecosystem functioning characterization, one based on communities of aquatic macrophytes (Rhine plain) and the second on oligochaete assemblages (Yzeron basin). The two bio-typologies mainly reflect water exchanges between surface water and groundwater. In the Rhine plain, morphodynamics of the D3 geomorpho-type modify the tendency of increasing in the trophic level from upstream to downstream areas, this increasing being only verified for the D4 geomorpho-type. Indeed, morphodynamics of the D3 geomorpho-type prevents channel clogging and activates the limnocrene groundwater springs, inducing water oligotrophication and increase of biodiversity. In the Yzeron basin, which is impacted by polluted urban water runoffs, the B3 and A1 geomorpho-types present the highest values of ecological potentials (EPs) due to greater slopes and active surface water/groundwater exchanges. Results suggest that some biological characteristics and ecological functions could be spatialized on larger spatial scales through appropriate geomorphic river typologies.

Oligochaete Assemblages Associated with Macrophytes in the Liangzi Lake District, China

ABSTRACT The assemblage of oligochaetes in the Liangzi Lake District, located in middle reaches of the Changjiang River, was studied from May to August, 2001. To establish species composition, richness, and abundance and detect the influence of environmental variables on oligochaete distributional patterns, 45 localities were sampled. All total, 20 species belonging to the families Naididae (eight species), Tubificidae (11 species), and Lumbriculidae (one species) were found. Branchiura sowerbyi, Tubifex sp. 1, and Aulodrilus pluriseta were the dominant species and contributed nearly 70% of the total abundance. The 45 sampling sites were separated into three groups based on composition and relative abundance of benthic oligochaete communities using two-way indictor species analysis associated with detrended correspondence analysis. Canonical correspondence analysis indicated that two plant variables (total plant cover and total submersed macrophyte biomass) were strongly correlated with the faunal gradient (p<0.05). Other predicator variables were water depth and total nitrogen.

Studies on the aquatic oligochaete fauna in Lake Biwa, central Japan. IV. Faunal characteristics in the attached lakes (naiko)

Surveys for macroinvertebrates occurring in 20 small attached lakes (naiko) adjacent to Lake Biwa, central Japan, conducted in 2001–2002 yielded 44 taxa of aquatic oligochaetes (Annelida, Clitellata). Descriptions and taxonomic remarks are provided for nine species: Aulophorus furcatus, A. tonkinensis, A. flabelliger, Pristina biserrata, P. proboscidea, Ilyodrilus templetoni, Allonais pectinata, Stylaria fossularis, and Dero dorsalis; the former six species of these are new to Japan. Stylaria fossularis is regarded as a distinct species, distinguished from the congener S. lacustris, on the basis of prostomium morphology and geographical distribution. No distinctive oligochaete fauna can be seen in the individual naiko, but as a collective body they maintain a rich fauna. This fauna was richer in naidines, while poorer in other groups of oligochaetes than those in Lake Biwa, and basically can be regarded as an extension of the fauna of littoral Lake Biwa. Epiphytic oligochaetes were more diverse and more abundant in the naiko than those in littoral Lake Biwa, probably because of higher temperatures, denser aquatic vegetation, and higher primary production. Summer oligochaete assemblages in the naiko were predominated by Stylaria fossularis and include several species characteristic of subtropical and tropical Asia, suggesting a close relationship to the fauna of the Indo-Malayan zoogeographical subregion.

Surface and Hyporheic Oligochaete Assemblages in a French Suburban Stream

The Chaudanne stream received urban inputs discharged through combined sewer overflows (CSOs). The water quality was not severely impaired, with pollution mainly of organic origin. Oligochaete assemblages were studied in the coarse surface sediments and the hyporheic zone and sampled at four sites on seven occasions during 2000 and 2001. The seasonal distribution of oligochaete assemblages was analyzed by a PCA, the oligochaete species being assigned to functional traits (FTrs). Site 1, located upstream of the CSOs, was characterized by FTrs 1 and 2 (species indicating permeability and those intolerant to water pollution). Below the CSOs, high densities of oligochaetes occurred in the benthic layer of sites 3 and 4, with a predominance of FTr3 (species with tolerance to water pollution). At site 4, FTr4 species (indicative of sludge conditions) constantly predominated in the hyporheic system, but predominated in the benthos only during low stream discharges associated with peaks in CSOs. FTr3 was related to amounts of the oxidized forms of nitrogen, high stream discharges and probably to groundwater upwellings and the sludge tolerant species group (FTr4) was associated with high NH 4 + contents. We are now testing the relevance and generalization of this new approach.

Oligochaete Assemblages in the Hyporheic Zone and Coarse Surface Sediments: Their Importance for Understanding of Ecological Functioning of Watercourses

The hyporheic zone and its interactions with coarse surface sediments is increasingly reported by aquatic ecologists because the water exchanges between surface and subsurface are important factors for the understanding of the ecosystem functioning. However, the hyproheic oligochaete assemblages have received less attention than other assemblages such as crustaceans. In addition, studies investigating the incidence of pollution in watercourses have mostly focused on the benthic zone and have neglected the hyporheic zone. Some examples are given from an unpolluted glacial river (Roseg), polluted plains rivers (Moselle, Rhône) and a protected wetland in an urbanized environment. The hyporheic zone kept the memory of past and present incidences of pollution, in particular when downwellings of polluted surface waters to the hyporheic zone predominated. The Active hydrologic Exchange Describers between surface and subsurface (AED oligochaete species) were the same in the glacial river Roseg, the rivers Rhône and Moselle and the urbanized wetland. The predominance of pollution-tolerant species like Limnodrilus hoffmeisteri was observed in polluted groundwater as well as in polluted surface coarse sediments. Moreover, the urbanized wetland exhibited a high species richness, suggesting that the hyporheic zone is a reservoir of species. The oligochaete communities enable biologists to simultaneously assess the pollution incidence, the permeability of coarse habitats, the water exchanges between surface and subsurface, and give an approximate measure of the metabolic activities in the sediments. Consequently, the simultaneous study of surface and hyporheic oligochaete assemblages is of great interest when considering the ecological functioning of watercourses and the incidence of pollution inputs.