Study on zooperiphyton and zoobenthos of a small river

The special traits of zooperiphyton and zoobenthos structures in a small river were studied. Under conditions of maximal proximity of niches, these groups of invertebrates retain taxonomic and ecological heterogeneity. Differences in zooperiphyton and zoobenthos taxonomic structures are most pronounced in terms of presence of dipterans, oligochetes, and mollusks. In the periphyton, the dominant groups are chironomid (orthocladines, chironomines, and tanitarsines) larvae, oligochetes of fam. Naididae and mollusks of fam. Limnaeidae. In the benthos chironomid (chironomines and tanirodines), oligochetes of fam. Tubificidae, and mollusks of fam. Pisidiidae are dominant. On average, the bottom invertebrates are considerably larger than fouling organisms. At similar abundance values, the biomass of benthos is by an order of magnitude higher compared to zooperiphyton. Ranging of average biomasses of zooperiphyton and zoobenthos revealed that the leader common for both communities is the large and mobile predatory leech, Erpobdella octoculata (Linnaeus). The anthropogenic impact and zoogenic (beavers) impact upon the river biota are comparable to each other.     

Changes in the zooperiphyton structure in a small river along the spatial gradient

A total of 165 taxa have been recorded in the zooperiphyton of the Sestra River, among which larvae of chironomids (40), nematodes (24), and oligochaetes (21) have the highest species richness. The increase in the taxonomic richness of zoocenoses from the river head to its mouth is weakly expressed. The highest diversity of zoocenoses is characteristic for the contact zones of the river water with its tributaries and receiving waters. The discreteness of spatial characteristic of the taxonomic composition of zooperiphyton reflects the heterogeneity and diversity of habitat conditions of invertebrates. In regards to its effect on zoocenoses, anthropogenic pollution can exceed the impact of many environmental factors (including the current velocities) which affect the formation of rheophilic communities in river ecosystems. The dominant complexes of zooperiphyton include all trophic groups of invertebrates, among which the group of detritophages-collectors has the highest taxonomic diversity. The group of phytodetritophages-filterers + collectors mainly includes chironomid larvae of the genus Chironomus, which are associated with strongly polluted zones. Invertebrate filterers, sponges, and bryozoans prevail mainly in zooperiphyton in the lower reaches of the river, which are not subjected to the pollution.     

Spatial structure of zooperiphyton in a small river (West Siberia)

Basic quantitative characteristics of zooperiphyton from the Uk River are presented. Factors effecting the composition and structure of invertebrates have been found. The effect that the current velocity, water level, and different types of pollution have on zooperiphyton in the small river is shown. The pollution of the river reduces taxonomic diversity. The maximum effect is caused by the discharge of mineralized waters. In clean portions of the river, Trichoptera dominate in biomass; in polluted parts, their role decreases and the larvae of chironomids and leeches prevail in zooperiphyton.     

Comparison of zoobenthos and zooperiphyton of large and medium rivers

The results of a study of zoobenthos and zooperiphyton of two rivers of the Ob’ River middle reaches are shown. A comparative analysis of the composition and abundance values of two ecological groups of zoobenthos and zooperiphyton hydrobionts has revealed the difference in their taxonomic compositions and dominant complexes. The similarity in total number and biomass of zoobenthos and zooperiphyton in the large river and the higher values of zooperiphyton quantitative development in a medium river have been identified.     

Basic characteristics of zooperiphyton in large rivers of Western Siberia (Tyumen oblast)

The data on the qualitative and quantitative composition of zooperiphyton from seven large rivers of Western Siberia are presented. The species similarity of zooperiphyton has been documented in most of the rivers. The biomass in unpolluted parts is mainly formed by the larvae of caddis flies. Factors which effect the composition and structure of zooperiphyton have been determined. Changes in the structure and quantitative development of zooperiphyton are shown.     

Phytophilous zoocoenoses of Lake Teletskoye

The composition, structure, and spatial distribution of zoobenthos and zooperiphyton at plantfilled regions of the littoral of Lake Teletskoye have been analyzed. The dependence of the taxonomic composition, number, and biomass of zoobenthos on vegetation type has been discovered. A multilevel character of the distribution of invertebrates in macrophyte overgrowths has been shown. An analysis of the trophic structure of the communities of macroinvertebrates revealed the predominance of algodetritophagous animals in zooperiphyton. The role of plant overgrowth as a “life concentrator” in an oligotrophic lake has been revealed.     

On the interrelation of diversity and structural and functional indicators of hydrobiont communities

Empirically derived relationships between indicators of diversity of zoobenthos, zooperiphyton, and zooplankton and the structural characteristics of communities in reservoirs of various types are presented. The relationships between indicators of diversity, the biomass of communities, the spatial structure, and the ratio of energy stored in biomass and scattered energy have been elicited.     

Successions of zooperiphyton in a small river

In the small Latka River, which is characterized by a high heterogeneity of abiotic characteristics and a rich fauna composition, a high diversity of developing zooperiphyton structures was recorded consisting of invertebrates with short life cycles: the larvae of chironomids, caddisflies, mayflies, oligochaetes, nematodes, and other animals. One distinctive feature of seasonal and interannual zooperiphyton succession is the annual prevalence in abundance of spreading chironomid larvae of age I, which belong to the most representative dominating group of amphibiotic invertebrates, including species adapted to different saprobic conditions. The taxonomic and quantitative domination of chironomids make it possible to consider the family Chironomidae a key group in the formation of the zoocenosis structure. Under disturbed habitat conditions (pollution, rainfall floods, and the press of omnivorous invertebrates), the restoration of typical structures occurs rather quickly due to the particular features of biology in species short life cycles. However, no relative stabilization in communities was observed. This is the main difference between the sequence of succession processes in the Latka River and that observed in large water bodies (lakes and water reservoirs), where there are no strict limitations on living-space volume or food availability and abiotic conditions are more stable, thus allowing filter-feeding sessile animals (sponges, bryozoans, and zebra mussels) to develop on solid substrates. These species are able to develop multispecies consortia and form relatively stable long-term communities.     

Taxonomic and trophic structures of dominants in the zooperiphyton of waterbodies and watercourses of the upper Volga basin

All the main trophic groups of invertebrates are presented in the compositions of dominant assemblages of zooperiphyton in the studied waterbodies and watercourses. The strong pollution of water by suspended solids of anthropogenic origin in the water of the upper Volga reservoirs leads to the suppression of typically sessile filter-feeding invertebrates (sponges, bryozoans, and Dreissena) able to form the highest biomass of zooperiphyton using natural food items. The conditions of the disturbed structure of food resources are favorable for the development of detritivores-gatherers. In small rivers receiving industrial wastewaters, excessive amounts of food in the water column and in the form of sediments on the substrates suppresses invertebrates-biofowlers and facilitates the expansion of the benthic larvae of chironomids of g. Chironomus (combining the filtration and gathering of food particles on the substrates) to the vacant spatial niches. At the same time, the role of nematodes and oligochaetes with prevailing detritophages increases. In the acidified lakes of the Darwinsky National Reserve, the decrease in the total species diversity of zooperiphyton is accompanied by decreases in the role of filter-feeding invertebrates. The chironomid larvae and oligochaetes prevailed in the poor zoocenoses. The roles of predatory caddisfly larvae, black gnats, and nematodes increased. The labile structural characteristics of zooperiphyton with the conservation of the historically formed methods of foraging are the main modern way that biofouling communities adapt to changes in the quality and quantity of food resources upon modern anthropogenic pollution of the aquatic environment.     

淀山湖周丛动物群落的初步研究

作者于1991年11月至1992年11月对淀山湖水生植物上周丛动物进行了初步研究。共观察到84种周丛动物,以原生动物(38.10%)和轮虫(22.62%)占多数。按个体大小,分为小型周丛动物群落和大型周丛动物群落两种群落类型。小型周丛动物群落的优势种为似钟虫、角突臂尾轮虫等,个体数量受周丛原生动物支配,一年中有两次高峰(3-4月份和11月份),生物量在3月份最大,主要受周丛轮虫控制。大型周丛动物群落的优势种为线虫和螺类,一年只有一次数量高峰(6-8月),生物量中螺类占绝对优势(96.4%)。周丛动物在不同水生植物上的分布数量不同,沉水植物中以金鱼藻最多,大茨藻最少;并且叶上的数量明显高于茎上。漂浮植物上一般多于沉水植物,且根部最多,茎、叶相近。水生植物上周丛动物多为广布种,特有种罕见,主要出现于小型周丛动物群落中。       

Catchment-scale biogeography of riverine bacterioplankton

Lotic ecosystems such as rivers and streams are unique in that they represent a continuum of both space and time during the transition from headwaters to the river mouth. As microbes have very different controls over their ecology, distribution and dispersion compared with macrobiota, we wished to explore biogeographical patterns within a river catchment and uncover the major drivers structuring bacterioplankton communities. Water samples collected across the River Thames Basin, UK, covering the transition from headwater tributaries to the lower reaches of the main river channel were characterised using 16S rRNA gene pyrosequencing. This approach revealed an ecological succession in the bacterial community composition along the river continuum, moving from a community dominated by Bacteroidetes in the headwaters to Actinobacteria-dominated downstream. Location of the sampling point in the river network (measured as the cumulative water channel distance upstream) was found to be the most predictive spatial feature; inferring that ecological processes pertaining to temporal community succession are of prime importance in driving the assemblages of riverine bacterioplankton communities. A decrease in bacterial activity rates and an increase in the abundance of low nucleic acid bacteria relative to high nucleic acid bacteria were found to correspond with these downstream changes in community structure, suggesting corresponding functional changes. Our findings show that bacterial communities across the Thames basin exhibit an ecological succession along the river continuum, and that this is primarily driven by water residence time rather than the physico-chemical status of the river.     

Seed dispersal by rivers in tropical dry forests: An overlooked process in tropical central Mexico

Aims

Rivers are important corridors for the movement, migration and dispersal of aquatic organisms, including seeds from riparian plants. Although tropical dry forests (TDF) are among the most extensive and floristically rich ecosystems of tropical habitats, and the most globally endangered ecosystem, less attention has been given to riparian corridors within this ecosystem. Although most TDFs manifest peak seed dispersal during dry seasons, we hypothesized that riparian corridors may show a dispersal peak during the rainy season, due to an anticipated ‘sweep or drag effect’, resulting from river overflow and bank erosion. Our main aims were to investigate whether there were any differences in the seed communities transported by the river to sites in rainy as opposed to dry seasons, and to evaluate any possible relationship between the riparian seed community and river flow.

Location

Amacuzac River, drainage of the Balsas basin, State of Morelos, Mexico.

Methods

To evaluate the above assumption, we associated Amacuzac River flow with the number of species and seeds dispersed by water. We also characterized and evaluated differences between seed communities transported by the river during the rainy and dry seasons, and between four different sites located along the river. We used univariate and ordination NMDS techniques to evaluate patterns between seasons at the community level.

Results

Forty‐five plant species were identified from 909 seeds collected from the river. The composition of riparian seed communities was markedly different between seasons but not between sites. Seed abundances were significantly higher in the rainy than in the dry season and varied between sites. Seed species diversity in the river (H’ = 1.6–1.9) showed no significant differences between seasons or sites, but species assemblages and dominance varied according to season. Ordination techniques and subsequent fitting analyses showed that seed species composition was positively associated with river flow.

Conclusions

Seed dispersal patterns generated by rivers are significant mechanisms for structuring the composition and distribution of the riparian plant community in Mexican TDF. Varying species assemblages and seed abundance dispersed by the river throughout the year is a relevant and until now unknown consequence that may affect the dynamics and composition of riparian plant communities in this region. This study initiative will promote new avenues of research regarding plant establishment and succession.     

Similarities in zooplankton community between River Drawa and its two tributaries (Polish part of River Odra)

Zooplankton communities were studied in a river and its tributaries with different hydrological, biological and physico-chemical conditions. Small similarities were noted in the zooplankton community (mostly Rotifera) between a tributary characterised by a regular bed and the river. No influence of a tributary with an irregular bed and variable water flow was noted on the zooplankton of the river it joined. It was concluded that the tributaries had very little influence on the zooplankton community in the river which they joined. The most probable reasons for this were the predatory behaviour of fry, escape of zooplankton into the river vegetation and therefore not carried down by the river current, and reproduction of zooplankton in slack waters, small floodplains and densely vegetated riparian zones of the main river.     

Communities of Chironomid larvae in the Velika Morava river

The following communities of Chironomid larvae were found: psamorheophile, psamophile, pelorheophile, pelophile and phytorheophile. They differ according to both their coenotical composition and the number of organisms, and show a particular distribution along the river course in correlation with the type of substrate. The most widespread are the psamorheophile communities and the most restricted the phytorheophile ones.     

Tributary and mainstem benthic macroinvertebrate communities linked by direct dispersal and indirect habitat alteration

Benthic communities in tributary–mainstem networks might interact via downstream drift of invertebrates or material from tributaries and adult dispersal from the mainstem. Depending on the strength of these interactions, mainstem downstream communities are expected to be more similar to tributary communities due to drift or habitat alteration. Communities not connected by flow are expected to be similar due to adult dispersal but decreasing in similarity with distance from the mainstem. We investigated interactions between invertebrate communities of a 7th order river and 5th order tributary by comparing benthic community structure in the river upstream and downstream of the tributary confluence and upstream in the tributary. Non-metric multidimensional scaling showed invertebrate communities and habitat traits from river locations directly downstream of the tributary clustered tightly, intermediate between tributary and mid-channel river locations. In addition, Bray–Curtis dissimilarity increased between the mainstem and tributary with distance upstream in the tributary. Our results indicate that similarities between mainstem and tributary communities are potentially caused by direct mass effects from tributary to downstream mainstem communities by invertebrate drift and indirect mass effects by habitat restructuring via material delivery from the tributary, as well as potential effects of adult dispersal from the river on proximal tributary communities.     

Application of clustering techniques for the characterization of macroinvertebrate communities to support river restoration management

The European Water Framework Directive prescribes that the development of a river assessment system should be based on an ecological typology taking the biological reference conditions of each river type as a starting point. Aside from this assessment, water managers responsible for river restoration actions also need to know the steering environmental factors to meet these reference conditions for biological communities in each ecological river type. As such, an ecological typology based on biological communities is a necessity for efficient river management. In this study, different clustering techniques including the Sørensen similarity ratio, ordination analysis and self-organizing maps were applied to come to an ecological classification of a river. For this purpose, a series of sites within the Zwalm river basin (Flanders, Belgium) were monitored. These river sites were then characterized in terms of biotic (macroinvertebrates), physical–chemical and habitat variables. The cluster analysis resulted in a series of characteristic biotic communities that are found under certain environmental conditions, natural as well as human-influenced. The use of multiple clustering techniques can be of advantage to draw more straightforward and robust conclusions with regard to the ecological classification of river sites. The application of the clustering techniques on the Zwalm river basin, allowed for distinguishing five mutually isolated clusters, characterized by their natural typology and their pollution status. On the basis of this study, one may conclude that river management could benefit from the use of clustering methods for the interpretation of large quantities of data. Furthermore, the clustering results might enable the development of a cenotypology useful for efficiently steering river restoration and enabling river managers to meet a good ecological status in most of the rivers as set by the European Water Framework Directive.     

Hydrobiological studies on the Tugela River system

Summary A survey of pollution in the Bushmans river, and a tributary, the Little Bushmans river in the vicinity of Estcourt, Natal, is described. The pollution arose mainly from wastes discharged from a boardmill, a milk-processing factory, and a sewage-disposal, irrigation farm. The effects of these effluents on the chemistry of the river waters, and on the biological communities in them is described.The communities at polluted stations have been classified in relation to the degree of pollution, and the equivalence of the classification with the systems described by other workers has been indicated. Differences observed between communities in normal and polluted stretches of the rivers are suggested as indices of pollution.     

Response of microbial communities to elevated thallium contamination in river sediments

Abstract

The study of microbial communities in river sediments contaminated by thallium (Tl) is necessary to achieve the information for in-situ microbially mediated bioremediation. However, little is known about the microbial community in Tl-contaminated river sediments. In the present study, we characterized the microbial community and their responses to Tl pollution in river sediments from the Tl-mineralized Lanmuchang area, Southwest Guizhou, China. Illumina sequencing of 16S rRNA amplicons revealed that over 40 phyla belong to the domain bacteria. In all samples, Proteobacteria, Cyanobacteria, and Actinobacteria were the most dominant phyla. Based on the UPGMA (Unweighted Pair Group Method with Arithmetic Mean) tree and PCoA (Principal Coordinates Analysis) analysis, microbial composition of each segment was distinct, indicating in-situ geochemical parameters (including Tl, sulfate, TOC, Eh, and pH) had influenced on the microbial communities. Moreover, canonical correspondence analysis (CCA) was employed to further elucidate the impact of geochemical parameters on the distribution of microbial communities in local river sediments. The results indicated that a number of microbial communities including Cyanobacteria, Spirochaete, Hydrogenophaga, and Acinetobacter were positively correlated with total Tl, suggesting potential roles of these microbes to Tl tolerance or to biogeochemical cycling of Tl. Our results suggested a reliable location for the microbial community’s diversity in the presence of high concentrations of Tl and might have a potential association for in-situ bioremediation strategies of Tl-contaminated river. Overall, in situ microbial community could provide a useful tool for monitoring and assessing geo-environmental stressors in Tl-polluted river sediments.     

Spatial and temporal variability in epilithic biofilm bacterial communities along an upland river gradient

Riverine biofilms remain one of the least-studied habitats despite the significant increase in the examination of aquatic microbial communities in recent years. In this study, the dynamics of epilithic biofilm communities native on rocks from a low-order upland stream were examined over a period of 3 years. Spatial and temporal variations in bacterial communities were assessed using terminal restriction fragment length polymorphism, based on analysis of the 16S rRNA gene. In total, 108 epilithic biofilm samples were analysed and 170 different ribotypes were detected. A strong temporal gradient in ribotype composition was noticed, especially between samples collected in 2001 and those collected in 2002 and 2003, most likely reflecting interannual differences in weather conditions, such as temperature. A spatial gradient in ribotype composition, from upstream sites to the low-lying sites, was also evident and interpreted as an environmental variation gradient along the river course. Distinct biofilm communities consistently occurred at the first site along the river, which was significantly correlated to low pH. Temporal factors explained the highest degree of variation within the epilithic biofilms. Recurrent blooms of certain bacteria were noted within the system. Phylogenetic relationships of bacteria at one point in the river were determined using a cloning and sequencing approach, with Alphaproteobacteria dominating the community, followed by Cyanobacteria, Bacteroidetes and Betaproteobacteria.     

Deep living Planktothrix rubescens modulated by environmental constraints and climate forcing

To verify whether the variability in benthic invertebrate communities along the mountainous Czarny Dunajec River is mainly driven by the variation in hydromorphological or water quality, diversity of the communities was determined for 18 cross-sections with 1–5 low-flow channels and compared with the complexity of physical habitat conditions and with physico-chemical water quality. An increase in the complexity of flow pattern in the river was associated with increasing cross-sectional variability in physical habitat parameters. Distinct hydromorphological characteristics of the cross-sections with a given number of low-flow channels were especially pronounced if the analysis was limited to the parameters measured directly, whereas calculated complex hydraulic and sedimentary variables represented information overload. Taxonomic richness of the invertebrate communities was unrelated to physico-chemical water parameters, which consistently pointed to the high water quality. Instead, the richness positively correlated with a degree of variation in physical habitat parameters and was best predicted by the number of low-flow channels in a river cross-section. This study indicates that physical habitat complexity in a mountain river can be considered a proxy to the diversity of its invertebrate communities and that restoration of such complexity will be necessary for future recovery of invertebrate communities in impacted river sections.