Analysis of chlordane-impacted streams using chironomid pupal exuviae (Diptera: Chironomidae)

A method of rapidly assessing streams and rivers using chironomid pupal exuviae was tested on a chlordane-impacted stream near St. Louis, Missouri. Various concentrations of chlordane were found in sediments of Grand Glaize Creek, most likely resulting from soil runoff around housing and business developments throughout the stream's course. Chironomid pupal exuviae and sediment samples were collected concurrently from Grand Glaize Creek on two separate occasions, once in 1988 and again in 1990. Cluster analysis of samples at sites, based on the percent abundances of taxa within habitats and by subfamilies, produced two distinct clusters; one grouping samples with lower chlordane concentrations and the other grouping samples with higher chlordane concentrations. Further analysis showed a trend towards lower percent abundances of taxa living in depositional and transitional/depositional zones (Chironominae and some Tanypodinae) at the higher chlordane site, while the lower chlordane sites had lower percent abundances of taxa within erosional and erosional/transitional zones (Orthocladiinae and some Tanypodinae). These findings support the hypothesis that taxa living in close association to fine organic sediments will be exposed to higher concentrations of chlordane in the stream and more negatively affected than taxa feeding and living in habitats removed from chlordane-bound sediments. Comparisons from the present study were made to related studies revealing similar patterns among the Chironomidae.     

Monitoring organic enrichment of rivers using chironomid pupal exuvial assemblages

Exuvial samples were collected at stations above and below organic effluent inflows at twenty river sites near Bristol, England, during May, July and September, 1989.Exuvial sample data for each station were amalgamated and related to chemical data obtained from the Wessex and the Severn-Trent Regions of the National Rivers Authority. Principal Components Analysis (PCA) and Canonical Community Ordination (CANOCO) were used to derive biplots of taxa and selected environmental factors. From these biplots, lists of taxa were obtained, and ranked in order of closeness of association to selected organically-related environmental factors. Lists of principal taxa, either positively or negatively associated with a given environmental factor, were termed indicator assemblages in respect of that factor.The rank orders of similarity of these indicator assemblages to amalgamated exuvial samples from 51 stations on the River Trent, were significantly correlated (p<0.001) to the same stations ranked in order of ammonia concentrations and biological oxygen demand (BOD.).     

Diel emergence patterns of drifting chironomid (Diptera) pupal exuviae in the Aude River (Eastern Pyrenees,France)

Two diel emergence patterns (April and October 1990) of chironomids from a hyporhithral site (4th–5th order) in the Aude River are described. In April, 62 species were collected with a mean hourly richness of 31 (±4). The Orthocladiinae (91%) largely dominated the emergence. The total number of exuviae captured by one drift-net varied from 1300 to 11600 per one hour period. There was a clear bimodal pattern with peaks post dawn (07.00–09.00 hrs) and around sunset (18.00 hrs).In October, the total number of exuviae captured was much lower and varied from 150 to 540 per one hour period with post dawn (06.00–08.00 hrs) and post sunset (18.00 hrs) peaks. Nevertheless, the total species richness (65) was higher as was the mean hourly richness (37±4). The Orthocladiinae (68%) dominated less because of increases in the Tanytarsini (15%) and Chiromini (14%). A diel rhythm appeared in autumn emergence. Most of the Orthocladiinae exuviae were collected during daylight hours, whereas most of the Chironomini and Tanytarsini were sampled during darkness. A majority of the exuviae with a length below 3 mm emerged during daylight, but most of the exuviae above 5 mm length emerged during darkness. The exuviae with an intermediate length (3–5 mm) had an amodal diel emergence pattern. In spring and autumn, the majority of species had a bimodal emergence pattern either by day (Orthocladiinae) or by night (Chironominae). But the smallest species had either an unimodal (Thiennemaniella vittata) or bimodal (Neozavrelia fuldensis) daytime emergence. The diel emergence patterns of 10 of the most frequently recorded species are presented.     

Correlations between chironomid pupal skin collections and habitats recorded from a chalk river

Chironomid pupal skins were collected during one year from three sites along a chalk stream in southern England. The sites had similar chemistry and discharge but differed in their current and temperature regimes. Substrate composition upstream of each collection point was surveyed during spring, summer and autumn. Proportions of macrophytes and sediments were compared with proportions of chironomid species and trophic groups. Seasonal changes in substrate and pupal skin collections were correlated by classification and direct ordination techniques. The distribution of chironomid species were indicated as being significantly related to the recorded substrate data.     

Chironomid pupal exuviae and larvae of two storage reservoirs in The Netherlands

For three years chironomid larvae were collected bimonthly with a grab sampler in two deep storage reservoirs in The Netherlands. Chironomid pupal exuviae were collected monthly, from April to November, with a handnet. Net samples yielded more taxa than grab samples. The taxa found in net samples originated from more habitats, than taxa found in grab samples. The relative contribution of Orthocladiinae was much larger in net samples. Based on the results obtained in the two reservoirs, some advantages and disadvantages of both sampling methods are discussed.     

The zooplankton of the lower river Meuse, Belgium: seasonal changes and impact of industrial and municipal discharges

Between 1991 and 1993, samples were collected upstream and downstream of the industrial basin and urban centre of Liège. Rotifers and crustaceans (cladocerans and copepods) were identified and counted. Their population dynamics were related to physical and chemical factors (temperature, oxygen, ammonium, nitrates, nitrites, phosphates) and to phytoplankton biomass. The zooplankton was dominated by rotifers; crustaceans (cladocerans and copepods) were less abundant. There was a succession of groups and species, some thriving in the spring and others in summer or autumn. The dominant rotifer species were Brachionus calyciflorus Pallas, Brachionus angularis Gosse, Keratella cochlearis (Gosse) and Synchaeta spp.; B. calyciflorus and B. angularis are spring species. K. cochlearis was present between May and November. Crustacean biomass was important in summer and autumn, but the faunal spectrum and biomass also varied with sampling location. Low spring and summer discharges allowed the phytoplankton to develop significantly. The zooplankton development followed a similar pattern. During low flow, when plankton populations become established, some declines in phytoplankton could only be explained by sedimentation and grazing pressure by zooplankton. Although these factors provided a good explanation of the longitudinal variation, some local conditions (e.g. oxygen deficit, high level of phosphate) also induced changes (e.g. industrial and municipal waste water discharge).     

Bacterioplanktonic biomass and production in the river Meuse (Belgium)

This paper presents results of bacterial biomass determination by epifluorescence microscopy after acridine orange staining and ³H-thymidine incorporation measurements in the river Meuse. Bacterial production is calculated from thymidine incorporation using an experimental conversion factor (0.5 10¹⁸ bacterial cells produced per mole of thymidine incorporated into macromolecules). Seasonal variations of bacterial biomass and production at two stations are presented. Biomass ranges between 0.05 mgC · 1⁻¹ (in winter) and 0.8 mgC · 1⁻¹ (in summer). The variations of bacterial production seem to be closely linked to those of primary production; values lower than 1 μgC · 1⁻¹ · h⁻¹ are found in winter and high values (> 5 μgC 1⁻¹ · h ⁻¹) in summer. Longitudinal profiles in the Belgian course of the river show important increase of biomass and production from upstream to downstream. Bacterial growth yield (Y) has been determined (Y = 0.3) in order to calculate bacterial carbon uptake from bacterial production.     

One decade of benthic macroinvertebrate biomonitoring in the River Meuse

The benthic macroinvertebrate community of the River Meuse was studied at four locations in Belgium and The Netherlands from 1983–1993. Macroinvertebrates were collected from artificial substrates, placed near the river bottom from June–August. The results were analyzed using autecological information. At an upstream sampling site in the Belgian Ardennes (Hastière) the most diverse fauna was found. One quarter of the taxa found at this site are known to be confined to running waters and none of the dominant or subdominant taxa could be characterized as a specialized riverine taxon. These findings indicate an impoverished riverine fauna. This was especially the case in years with low discharge, indicating a delicately balanced ecosystem, easily susceptible to disturbances in the environment. Further downstream, in the heavily industrialized region of Liège (Hermalle) and just across the Belgian-Dutch border (Borgharen) the macroinvertebrate fauna consisted of taxa tolerating severe organic pollution. The ecosystem at these sites is on the brink of collapse. Recent results indicate an improvement of this situation at Borgharen. The macroinvertebrate fauna in the lowland reach (Keizersveer) indicates ecological recovery. It is concluded that abatement of the severe pollution must be the first step for an ecological rehabilitation of the degraded ecosystem and for the safe drinking water supply for millions of people in Belgium and The Netherlands.This article is dedicated to my friend and colleague Nicole Frantzen, who died in 1992 at the age of 27.     

Comparison of different biological indices for the assessment of river quality: application to the upper river Moselle (France)

The aim of our study was to assess the water quality of the upper Moselle river by using biological indices. Simultaneous physico-chemical surveys were also undertaken from May 1999 to April 2000. Twelve sampling sites were selected in order to provide a wide range of potential pollution. Chemical analysis did not reveal any major problem of pollution. However a lower water quality resulting from domestic pollution was established for some sampling sites. A biological monitoring combining both macroinvertebrates and macrophytes was performed. Biological indices based on plant community structure and macrophyte composition were not pertinent tools, whereas simple indices based on taxonomic richness of particular groups of macroinvertebrates were strongly correlated with several chemical parameters, showing that such simple biological variables should represent powerful indicators of ecosystem degradation.     

River quality analysis using fuzzy water quality index: Ribeira do Iguape river watershed, Brazil

Intrinsic uncertainties and subjectivities of environmental problems have been increasingly dealt by using computation methods based on artificial intelligence. In order to evaluate this tool's applicability, this study proposed the creation of a new water quality index based on fuzzy logic, the fuzzy water quality index (FWQI). The performance of the index proposed in the present work is assessed through a comparison with several water quality indices (WQIs) suggested in the literature, using data from hydrographic surveys of the Ribeira de Iguape River, in the southwestern part do São Paulo State, Brazil, from 2004 to 2006. The index was reasonably close to the other indices and showed a good correlation with the WQI traditionally calculated in Brazil. This new index may also be used as an alternative tool for decision-making in environmental management.     

A survey of the distribution of chironomidae (Diptera,Insecta) of the river rhine by sampling pupal exuviae

During the period from 1981-07-23 to 1981-08-10, the River Rhine, from the Alps to the North Sea, was sampled for chironomid pupal exuviae. Samples were also taken from the Grande Canal d'Alsace and from selected tributaries. In all 78 samples were taken, of which 9771 exuviae were examined and 135 taxa identified. A species list is given showing the distribution of taxa between the principal regions of the river (Appendix 1). Samples were also taken to show the within-sample and between-sample variability, and one pair of samples was used to demonstrate the difference between the two banks of the river below the junction with the Main. The Rhine above the Bodensee has a diverse fauna dominated by Orthocladiinae. The Hochrhein near the entry of the River Aare, and the River Aare itself, also have a diverse fauna, but include many sediment-dwelling Chironominae. Below Strasbourg the fauna changes markedly, losing most of its sediment-dwellers, and shows a great increase of pollution-tolerant species. The fauna generally becomes less diverse and of poorer quality throughout the Oberrhein sections, and faunal changes are demonstrated that are related to the inflow of the Rivers Neckar and Main, Samples from the Mittelrhein gorge and the Niederrhein are generally dominated by two species ofRheotanytarsus and show a progressive reduction of diversity coupled to an increase of pollution-tolerant species. The low proportions of sediment-dwellers in the Niederrhein and the Waal, suggests that the sediments are unsuitable for the support of a normal chironomid fauna.     

Changes in agricultural intensity and river health along a river continuum

1. The impact of agricultural activities on waterways is a global issue, but the magnitude of the problem is often not clearly recognized by landowners, and land and water management agencies. 2. The Pomahaka River in southern New Zealand represents a typical lowland catchment with a long history of agricultural development. Fifteen sites were sampled along a 119-km stretch of the river. Headwater sites were surrounded by low-intensity sheep farming, with high-intensity pasture and dairying occurring in the mid-reach and lower reaches. 3. Water clarity decreased significantly from about 6 m in the headwaters to less than 2 m in the lower reaches. Benthic sediment levels increased significantly downriver, peaking at 35 mg m^??2 below several tributaries with high-intensity agriculture in their catchments. Periphyton levels were also significantly greater in the lower reaches than the headwaters, and coincided with increased nitrogen (DIN) and phosphorus (SRP) concentrations. 4. Macro-invertebrate species richness did not change significantly throughout the river, but species composition did with Ephemeroptera, and to a lesser extent, Plecoptera and Trichoptera dominating the headwater sites (where there was high water clarity, and low nutrient and periphyton levels). Downriver these assemblages were replaced by molluscs, oligochaetes and chironomids. 5. Canonical correspondence analysis indicated that agricultural intensity and physical conditions associated with agriculture activity (e.g. impacted waters, high turbidity and temperature) were strongly associated with the composition of benthic assemblages at differing reaches down the Pomahaka River. 6. The present results indicate that quantifying agricultural intensity within a catchment, particularly relative livestock densities, may provide a useful tool for identifying threshold levels above which river health declines.     

Response of diatom indices to simulated water quality improvements in a river

Various diatom indices are routinely used in European countries to monitor water quality in waterways. In order to assess their sensitivities and their integration interval after a sudden and lasting environmental change, epilithic diatom biofilms were transferred from several polluted rivers to an unpolluted stream. To monitor the changes of the index values, the biofilms were sampled in a first experiment 20 and 40 days after transfer, and in a second experiment 30 and 60 days after transfer. Sensitivities of the indices to the water quality improvement were assessed calculating the differences between the index values of the reference and the transferred assemblages. Some indices have intermediate sensitivities (BDI, GDI, ILM, SLA), others higher sensitivities (CEE, EPI, ROT, SPI, TDI). The integration interval of these indices was 40–60 days. Some differences were observed between the indices, but their results were homogeneous when compared to those obtained with other metrics such as Bray-Curtis or Chord distances, used to assess the difference between the transferred and the reference diatom assemblages. These other metrics showed that even after 60 days, the transferred assemblages still differed from the reference. This underlines that metrics do not have the same integration intervals and do not assess the same stresses; the choice of the metric used to assess water quality is of prime importance.     

Water quality of rivers in the drainage basin of Lake Peipsi

Water quality and general regularities that have taken place in the water quality of rivers in the drainage basin of Lake Peipsi have been studied. The lake is located in the basin of the Narva River. Several changes of the water quality of the lake in 1970–1990, caused by increasing human impact, have been observed. The water quality of Lake Peipsi depends on its pollution load whereby the main part of the pollution reaches the lake via rivers. In 1985–1989 an extensive research programme of the lake and its drainage basin was carried out. In this paper a part of these results as well as recent changes in the water quality of the rivers of the Estonian side are studied. In the last years an improvement of the general state of rivers in the drainage basin of Lake Peipsi has taken place; the content of organic substances and nutrients in the inflows of Lake Peipsi and in the Narva River (lake outflow) is decreasing.     

The effect of trophic/contaminant interactions on chironomid community structure and succession (Diptera: Chironomidae)

The effects of contaminants and organic pollution on the chironomid communities of two basins in Lac St. Louis, a river-lake on the St. Lawrence River above Montreal, Quebec, were assessed and compared using lake classification theory techniques and morphological deformity indices based on the ligulae and antennae ofProcladius, the dominant surviving component of the south-shore communities. Contaminants from the industrial complex around Beauharnois, Quebec, have seriously degraded communities along the south-shore gradient while the introduction of untreated domestic wastes from Laprairie, Quebec, has seriously affected the communities of the Laprairie basin. The interaction between trophic and contaminant effects constitutes a classic example of the setback or deflection in the trajectory of ecological succession in biological communities hypothesized by ODUM (1981, 1985).     

摇蚊幼虫分布及其与水质的关系

摇蚊幼虫是水体中分布范围广的一类水生昆虫 ,它们的一些种类对水质的变化 ,如营养盐、重金属、ｐＨ和溶解氧等极为敏感 ,另有些种类则适应有机污染、重金属类毒物污染。在水质的生物学评价工作中 ,利用其种类敏感和耐污染特性 ,反映水质的变化和污染程度 ,是生物监测重要的评价依据。 2 0世纪 80年代 ,欧洲许多国家在研究酸雨对生态环境影响时 ,多采用摇蚊幼虫作为指示生物 ,也有的利用摇蚊幼虫口器或触角形态变化监测湖泊或河流水质[1 0～ 1 3 ]。国内有关摇蚊的研究近年来多偏重于成虫的分类学研究[6、8、9],对幼虫的研究则多利用底栖大…     

Redox processes in recent sediments of the river Meuse, The Netherlands

Pore-water concentrations of inorganic solutes were measured at four locations in a recent sedimentation area of the river Meuse in The Netherlands. The pore-water concentration profiles were interpreted using the steady state one-dimensional reaction/transport model STEADYSED1. This model explicitly accounts for the organic matter degradation pathways and secondary redox reactions. Results show that the model reproduces the measured pore-water profiles of redox species reasonably well, although significant divergence is observed for pH. The latter is due to the absence of pH buffering by CaCO₃ in the model. At all locations, methanogenesis is the major pathway of organic matter degradation below 3 cm from the sediment-water interface. However, organic matter degradation rates by methanogenesis may be overestimated, because methane ebullition is not included. Differences in profiles of redox-sensitive ions among the four locations are explained by differences in depositional conditions, in particular the sediment accumulation rate and supply of organic matter.     

Revitalization of a northcentral Texas river,as indicated by benthic macroinvertebrate communities

Macrobenthic communities were surveyed in 1987–88 as part of acomprehensive study of fish kills and water quality in the upper TrinityRiver. The purpose was to characterize macrobenthic integrity in relation toambient and storm-associated water quality and other environmental factors.No physical habitat features were found to be substantially limiting toaquatic life. Water and sediment quality generally were good, andmacrobenthic communities typically were healthy. Ecological conditions werevastly improved compared to the recent past, attributable mainly todecreased contaminant loading from wastewater treatment plants and reducedincidence of raw sewage bypassing. Nonetheless, some impact was evident incertain reaches. Deleterious effects at Beach St. evidently resulted frompesticides derived from urban runoff. Slight impacts by dissolved metalswere suggested for Grand Prairie and Continental Ave.; possible sourcesincluded urban runoff and wastewater treatment plant effluents. Moderateimpacts at S. Loop 12 were attributed to low-flow toxicity induced by awastewater treatment plant discharge; ammonia and chlorine were consideredprimarily responsible, with metals and pesticides possibly involved.Macrobenthic communities were somewhat degraded from Trinidad to US 79, dueto storm-related stresses by DO depression, pesticides, and metallic oxides.Overall impacts were relatively slight on a long-term basis, however, and ahigh aquatic life use was attained at most sites. The degree of macrobenthicintegrity was considered remarkable for an effluent-dominated system withsuch extensive urbanization in the watershed.     

Water quality research in Loosdrecht lakes: the salient features

Ecosystem research by the working group Water Quality Research Loosdrecht lakes (WQL) was carried out from 1979 to 1990. A coordinated research programme, involving several research institutes and laboratories in The Netherlands, was initiated in 1983, i.e. a year before the reduction of external phosphorus loading by stripping, became effective. The paper summarizes the main results, with emphasis on insight they provide into the lake ecosystems.     

Evaluation of the water quality of future tributaries to the planned Dobczyce reservoir (Poland) using macroinvertebrates

The bottom fauna of 5 tributaries of the planned Dobczyce reservoir and the River Raba below the dam was investigated in the preimpoundment period (1983–84). The abundance of macrofauna varied between 46 taxa (Wolnica stream) and 66 taxa (Brzezówka stream). Each station showed individual taxa composition except for the RABA-u and RABA-d (84% similarity). On the basis of 7 different biological indices the stations were divided into 3 categories: unpolluted (Brzezówka), slightly polluted (Bulinka, Trzemésnia and both Raba stations), and moderately polluted (Wolnica). Most sensitive to chemical pollution was the BIOTIC-index. The combination of environmental variables was used to predict biological indices. The most significant relationship (P < 0.01, R² = 0.71) was found between the BIOTIC-index and physico-chemical factors. Some problems in the application of indices (sampling, indicator organisms and interpretation of the results) are discussed and local adaptations of methods used are recommended.