Ecological Water Quality Research Articles

Assessment of Soil Erosion in the Qinba Mountains of the Southern Shaanxi Province in China Using the RUSLE Model

The Southern Shaanxi Province, an important ecological security barrier area in central China, is the primary water source of the south-to-north water transfer project in China. However, severe soil erosion seriously affects the safety of regional ecological security and water quality of the water diversion project. To reveal the characteristics and variation of soil erosion in the southern Shaanxi Province after the implementation of a series of eco-environmental construction measures, in this study, the spatio-temporal characteristics of soil erosion from 2000 to 2014 were evaluated based on the Revised Universal Soil Loss Equation (RUSLE) model and Geographic Information Systems (GIS). The average soil erosion of southern Shaanxi Province in China was characterized as slight (less than 500 t·km–2·a–1) and mild erosion (500–2500 t·km–2·a–1) with an average soil erosion modulus of 1443.49 t·km–2·a–1, 1710.49 t·km–2·a–1, 1771.99 t·km–2·a–1 and 1647.74 t·km–2·a–1 in 2000, 2005, 2010 and 2014, respectively. The results revealed an increase in soil erosion until 2000 and a mitigation during the period of 2000 to 2014. After 2010, the soil erosion was controlled effectively. The spatial distribution of soil erosion displayed obvious spatial heterogeneity, and the high soil erosion (greater than 2500 t·km–2·a–1) was primarily distributed in the north-central and south counties of the study area. The soil erosion remained high and aggravated in six counties (i.e., Zhen’an, Zhashui, Ningshan, Ningqiang, Lueyang and Shanyang), and high erosion (greater than 5000 t·km–2·a–1) was found in the regions with slope gradients greater than 35 degrees and the middle mountainous (800–2000 m) regions. Therefore, the eco-environmental construction measures could effectively control soil erosion. However, unreasonable human activities remain the primary cause of soil erosion in the southern Shaanxi Province. In the future, more comprehensive and thorough ecological construction measures will be necessary to ensure regional ecological security and the eco-environmental quality of water sources.

Modeling of River Channel Shading as a Factor for Changes in Hydromorphological Conditions of Small Lowland Rivers

The ecological water quality in rivers and streams is influenced both by the morphological factors (within the watercourse channel and by the dynamic factors associated with flow), as well as biological factors (connected with the flora and fauna characteristic of its specific area). This paper presents an analysis of the effect of river channel shading by trees and shrubs on hydromorphological changes in a selected reach of the Wełna River, Poland. The analysis was conducted on two adjacent cross-sections (one in a reach lined with trees, the other in an open area with no tree or shrub vegetation). Data were collected during field surveys in the years 2014 and 2019. According to the Water Framework Directive, the Wełna River represents a watercourse with small and average-sized watershed areas, with sand being the dominant substrate of the river bottom. Flow volume, distributions of velocity in the sections, as well as substrate grain-size characteristics and river bottom morphology, were determined based on field measurements. In the study, the leaf area index (LAI) of vegetation was measured in the reach lined with trees, while the number and species composition of macrophytes were determined in the investigated river reaches. Moreover, a digital surface model (DSM) and Geoinformation Information System GIS tools were used to illustrate variability in shading within the tree-lined reach. The DSM model was based on Light Detection and Ranging (LIDAR) data. The results of this study enable us to establish the relationship between river shading by vegetation covering the bank zone, and changes in hydromorphological parameters of the river channel.

Biological index based on epiphytic diatom assemblages is more restrictive than the physicochemical index in water assessment on an Amazon floodplain, Brazil

Canadian Water Quality Index (CWQI) provides protection for freshwater life promoting healthy ecosystems and safeguarding human health. Biological Diatom Index (BDI) was developed to indicate the ecological status and water quality of freshwater systems. This paper evaluates the relations between the two different indices. During rising and falling, water samples were taken in the Curuai Floodplain, Brazil. CWQI was calculated using 14 physicochemical parameters and 1 microbiological parameter. The limits were established according to freshwater quality conditions and standards based on water use classes 1 and 2 determined in CONAMA 357 legislation and British Columbia. Canadian Water Quality Index categorization ranged from "marginal" to "excellent," most sampling units were "good" (71%), followed by "fair" (12%) and "excellent" (12%) water quality. Total phosphorus (38 times), chlorophyll a (20), dissolved oxygen (10), and total organic carbon (10) were the parameters that presented the most non-compliance values. Encyonema silesiacum (14%), Gomphonema parvulum (13%), and Navicula cryptotenella (12%) were the main taxa in the rising period, while G. lagenula, E. silesiacum, and Fragilaria capucina were the main taxa during the falling period. BDI ranges from I to V water quality classes. We observed "poor" to "very good" ecological status, with most sampling units "moderate" (52%) and "good" (29%). Water quality for class 2 was better than water quality for class 1, as the limits of the parameters evaluated were more restrictive in class 1 than in class 2 and the predominant uses of water require a higher degree of water purity. The biological index based on diatoms was the most restrictive index whose water classes and categorizations have shown an ecological status that could threaten the protection of aquatic communities on the Curuai floodplain. We suggest the combined use of both indices-physicochemical and biological for water quality assessment in this type of environment.

LUCC impact on water quality change in Xingyun Lake basin

Basin ecological environment and water quality are seriously threatened by development around the lake. The thesis intends to assess basin Land Use and land Cover Changes (here after abbreviated as LUCC) impact on water quality change in Xingyun Lake basin. To achieve this purpose, land use information was interpreted from six periods high-resolution images in the past 30 years, which were classified into seven land use types. The water quality data was obtained by investigation and collection. SPSS software was used to celebrate the correlation coefficient between water quality and LUCC. The results revealed that, in the study area construction land, transportation land and farm land were underwent an increase with the region development; grassland and bare land were gradually reduced, forest land had become fragmented. In addition, the water pollution index gradually increased since 2000, the water deteriorated significantly. Furthermore, there was a strong positive correlation between water pollution indicator and farmland, construction land and transportation land, which indicated that the deterioration of water quality may be the result of the combined effects of agriculture non-point source pollution, domestic and industrial pollution; there was a significant negative correlation between water pollution indicator and grassland and bare land, which indicated that permeable underlying mat had significant interception and absorption effects on pollutants.

Ecological water quality estimation of the middle course of the Southern Bug River by hydrochemical parameters

Ecological water quality estimation of the middle course of the Southern Bug River by hydrochemical parameters

Integrated ecological modelling for evidence-based determination of water management interventions in urbanized river basins: Case study in the Cuenca River basin (Ecuador)

The growth of urbanization worldwide has contributed to the deterioration of the ecological status of water bodies. Efforts at improving the ecological status have been made either in isolated form or by means of integrated measures by stakeholders, but in many cases, these measures have not been evaluated to determine their benefit. In this study, we implemented a scenario analysis to restore the ecological water quality in the Cuenca River and its tributaries, which are located in the southern Andes of Ecuador. For this analysis, an integrated ecological model (IEM) was developed. The IEM linked an urban wastewater system (IUWS) model, which gave satisfactory results in its calibration and validation processes, with ecological models. The IUWS is a mechanistic model that incorporated the river water quality model, a wastewater treatment plant (WWTP) with activated sludge technology, and discharges from the sewage system. The ecological status of the waterways was evaluated with the Andean Biotic Index (ABI), which was predicted using generalized linear models (GLMs). The GLMs were calculated with physicochemical results from the IUWS model. Four scenarios that would enhance the current ecological water quality were analyzed. In these scenarios, the inclusion of a new WWTP with carbon, and with carbon and nitrogen removal as well as the addition of retention tanks before the discharges of combined sewer overflows (CSOs) were assessed. The new WWTP with carbon and nitrogen removal would bring about a better restoration of the ecological water quality due to better nitrogen removal. The retention tanks would help to enhance the ecological status of the rivers during rainy seasons. The integrated model implemented in this study was shown to be an essential tool to support decisions in the Cuenca River basin management.

Effects of untreated industrial effluents on water quality and benthic macroinvertebrate assemblages of Lake Hawassa and its tributaries, Southern Ethiopia

The present study investigates the impacts of industrial effluents on the macroinvertebrate assemblages and water quality of the Lake Hawassa watershed. The water quality and macroinvertebrate assemblages were assessed at 40 sampling sites. The chemical and ecological water quality was evaluated using the Basic Prati index and the Ethiopian Biological Score Index (ETHbios), respectively. Canonical Correspondence Analysis (CCA) was used to evaluate the relationship between abiotic factors and macroinvertebrate metrics. A total of 5 876 invertebrates belonging to twentyfive families were recorded. The Coleoptera was the most dominant order represented by four families with a relative abundance of 68%. According to the ETHbios scoring system the sites receiving industrial effluent had very poor water quality (ETHbios score <12), whereas the upstream sites had moderate to good water quality (ETHbios 53 to 76). Likewise, the Basic Prati Index of the sites receiving industrial effluent was considered as very heavily polluted (Index score >8). Overall, the industrial effluents had a significant negative impact on water quality and macroinvertebrate diversity. Therefore, proper management of industrial effluent is urgently needed to prevent further deterioration of water quality and loss of biodiversity in the Lake Hawassa and Shallo Wetland ecosystems.

North German Lowland Lakes Miss Ecological Water Quality Standards—A Lake Type Specific Analysis

Despite great efforts in point source reductions due to improved wastewater treatment since 1990, more than 70% of the lakes in Germany have not yet achieved the “good ecological status” according to the European Water Framework Directive (WFD). To elicit lake type-specific causes of this failure, we firstly analyzed the ecological status of 183 lakes in NE Germany (Federal State of Brandenburg), as reported to the European Commission in 2015. Secondly, long-term data of two typical lakes (a very shallow polymictic lake with a large and a deep stratified lake with a small catchment area in relation to lake volume) and nutrient load from the common catchment were investigated. About 64%–83% of stratified and even 96% of polymictic shallow lakes in Brandenburg currently fail the WFD aims. Excessive nutrient emissions from agriculture were identified as the main cause of this failure. While stratified deep lakes with small catchments have the best chances of recovery, the deficits in catchment management are amplified downstream in lake chains, so that especially shallow lakes in a large catchment are unlikely to reach good ecological conditions. If the objectives of the WFD are not questioned, agricultural practices and approaches in land use have to be fundamentally improved.

Food Web Complexity of High Mountain Lakes is Largely Affected by Glacial Retreat

High mountain lakes provide essential ecosystem services and have a high conservation value. Therefore, understanding how glacier retreat will affect their ecological functioning and water quality is crucial. Here, we tested how shallow high mountain lakes having different glacial influences differ in their abiotic main features and food web structure using a multiple ecological indicator approach. We identified 13 functional groups within the planktonic and littoral communities, each one representing a biotic indicator and a node in a simplified food web network. The abiotic environment and most functional groups differed significantly as a consequence of the glacial influence. In general, runoff from glacial meltwaters resulted in highly simplified food webs. Considering that many turbid glacially fed lakes are losing their hydrological connection with disappearing/retreating glaciers and shifting to a clear state, our results suggest that this shift could enhance food web complexity, but at the cost of losing specific habitats. Further, retreat of large glaciers will form new glacially fed lakes, but it remains unclear whether this will buffer the expected habitat and biodiversity loss.

Ecological water health assessment using benthic macroinvertebrate communities (case study: the Ghezel Ozan River in Zanjan Province, Iran).

Macroinvertebrates are without spinal cord living organisms that spend their main phases of metamorphosis in water; so, changing the ecological structure of their communities represents environmental health condition. The main purpose of this study was to identify the macroinvertebrate families as a biological indicator and, consequently, determining the water ecological quality in the Ghezel Ozan River, NW Iran. The sampling was conducted at 18 stations in autumn 2017. At the same time, dissolved oxygen, temperature, turbidity, electrical conductivity, fecal and total coliform, BOD5, COD, phosphate, nitrate, nitrite, ammonia, chloride, and sulfate were measured based on APHA in each station. Then, based on the collected data, the NSFWQI, IRWQIsc, EQR, and BMWP/ASPT indices were calculated. In total, 1778 individual belong to 12 orders and 22 families were identified, which the most abundant order was Ephemeroptera by 47.8%. Except for the pH, COD, DO, and nitrogen compounds, other studied parameters were exceeded from their acceptable level. It seems that the geological characteristics are very effective in changing the parameters especially salinity. The best water quality was at Kharmaneh-Sar station (7), which runs from the protected area at high altitudes without human pressure. Also, the trend of water quality decreases from the upstream to downstream, which is completely in line with human activities. Therefore, the results of this study can well illustrate the role of land use and geology changes on the macroinvertebrate communities, which can be used to evaluate the ecological integrity of the river. Regular monitoring of river water quality and controlling and managing the quantity and quality of fish farms along the river can help in the ecological health of the river.

The diet of predatory fish in drinking water reservoirs – how can they contribute to biomanipulation efforts?

Efforts to positively influence ecological processes and water quality by manipulating the fish community (biomanipulation) are of particular importance in drinking water reservoirs. One of the principle measures employed is to increase the abundance of predatory fish species as a means of reducing planktonophagous and benthophagous cyprinids. However, there is little information available on the effectiveness of different predatory fish in biomanipulation exercises. We examined the diet of the five dominant predatory species (pike Esox lucius, zander Sander lucioperca, asp Leuciscus aspius, European catfish Silurus glanis, and perch Perca fluviatilis) in five representative reservoirs in the Morava River drainage basin (Czech Republic). Fish prey made up 75 % of total food intake, with undesirable small cyprinids dominant by biomass (40 %). European catfish and asp were not taken as prey and showed no sign of cannibalism. On the other hand, predation on conspecific predatory species (including cannibalism) was relatively high in perch, pike and zander, thereby reducing their net benefit overall. This little-considered aspect of predatory feeding needs to be taken into consideration in future biomanipulation stocking strategies.

САНІТАРНО-ГІДРОБІОЛОГІЧНА ХАРАКТЕРИСТИКА ОЗЕРА ВЕРБНЕ ЗА МІКРОФІТОБЕНТОСОМ

Assessing ecological and sanitary state of aquatic ecosystems, including their trophic and saprobiological status and impact of human factors, is among key objectives in modern hydrobiology.&#x0D; Apart from common hydrobiological methods (identifying species compositions, calculating algae number and biomass etc), there are specific methods for the assessment of aquatic ecosystems. Bioindication, which is based on aquatic organisms’ response to environmental factors, including human factors, is the most important.&#x0D; Microphytobenthos is highly sensitive to changes in natural and human factors. Its bioindication capabilities are widely known, therefore studying them as part of sanitary and hydrobiological characteristics of various water bodies is of great interest.&#x0D; Water basins across the City of Kyiv are under diversified human impact including various factors and effects, which differ in pressure degree. Thus, using microphytobenthos for sanitary and hydrobiological assessment, even within one type of water basins, has certain aspects, which depend on the bottom algal communities’ stability or degree of transformation. It is often caused by trophic and topic competition between microphytobenthos, phytoplankton and higher aquatic plants, as the latter two can inhibit growth of bottom algae.&#x0D; In the view of the above, special attention should be paid to quantitative characteristics of benthonts, which may act as cenose-forming organisms. The paper examines the findings of the studies on microphytobenthos in Verbne Lake, which is affected by negative human factor – contamination by surface and ground flow from Kyiv City area and is intensively used for recreation.&#x0D; The objective is to study the sanitary and hydrobiological characteristics and ecological quality of Verbne Lake according to microphytobenthos’ biondication indices.&#x0D; Benthic algae were sampled with the MB-TE microbenthometer within the littoral zone in triplicate from the total area of 40 cm2. Algae number was calculated on a counting plate in a 0.1 cm3 drop, their biomass was calculated according to geometric similarity method. Trophic and saprobiological values were assessed in accordance with the scale, proven for microphytobenthos. Saprobity index was calculated according to the Pantle-Buck method in Sladecek modification on the grounds of traditional and modern data on saprobity indicator algae.&#x0D; Benthonts, planktonts and periphytonts were distinguished with consideration taken of their association with particular habitats. Ecological classification of water quality was performed on the grounds of saprobity bioindication (saprobity indices) according to microphytobenthos. For microphytobenthos’ structural components their role in species richness, number and biomass were analyzed.&#x0D; Proceeding from the obtained findings, sanitary and hydrobiological characteristics of Verbne Lake were presented according to microphytobenthos. On the whole, the lake can be classified as mesotrophic, β-mesosaprobic water body. Benthonts proved to play an essential part in forming microphytobenthos’ indicatory characteristics. Intensive phytoplankton growth in the water column and its sedimentation upon the lake bottom inhibit development of benthic algal forms. In accordance with the ecological water quality classification based on microphytobenthos saprobity bioindication results (saprobity indices), the water of Verbne Lake relates to Water Quality Class II, Water Quality Category 3. The most unfavorable situation within the lake’s littoral area was registered in summer, which signals that self-purification processes are becoming less intensive and the aquatic ecosystem state is getting worse.

Grazing Potential—A Functional Plankton Food Web Metric for Ecological Water Quality Assessment in Mediterranean Lakes

Grazing potential (GP, in % day−1) was estimated for the plankton communities of 13 Greek lakes covering the trophic spectrum, in order to examine its sensitiveness in discriminating different classes of ecological water quality. Lakes with high GP values exhibited high zooplankton biomass dominated by large cladocerans or/and calanoids while lakes with low GP values had increased phytoplankton biomass and/or domination of small-bodied zooplankton indicating intensive fish predation. GP successfully distinguished among ecological water quality classes (estimated using the phytoplankton water quality index PhyCoI) indicating its potential use as a metric for ecological water quality assessment. As a next step, PhyCoI index was modified to include GP as a metric in order to enhance the phytoplankton-based ecological status classification of lakes incorporating zooplankton as a supporting factor. The PhyCoIGP successfully assessed the ecological water quality in accordance with PhyCoI classification whereas it was significantly correlated with the eutrophication proxy TSISD based on Secchi Depth. Thus, we propose to use the modified phytoplankton index PhyCoIGP for monitoring the ecological water quality of lakes.

SANITARY AND HYGIENIC ASSESSMENT OF WATER QUALITY IN THE DEVITSA RIVER OF THE UPPER DON BASIN BY THE PERIPHITON COMMUNITY OF ARTIFICIAL SUBSTRATES

We reviewed the issues of sanitary-hygienic assessment of water quality in the Devitsa River according to the indicators of periphyton of artificial substrates. The annually increasing level of water pollution requires the improvement of social and hygienic monitoring system. The issues of monitoring water bodies in the Voronezh Region is particularly relevant in the summer season, when rivers are used by the population for recreational purposes. To ensure the population safety, it is necessary to assess water by sanitary and hygienic indicators. Such assessment is carried out on the basis of the Hygienic and Epidemiological Center in the Voronezh Region, however, if sampling is carried out quite often and at different points for large and medium-sized rivers, that the limitation of sampling points and the total number of samples for small rivers does not allow for an objective determination of water quality and fully guarantee its compliance with sanitary and hygienic requirements. The solution to this problem can be the use of biological control as an additional method of monitoring, which allows to assess the ecological and sanitary-hygienic water quality in the river with the greatest accuracy along with hydrochemical control. As a bioindicator of the pollution level of a reservoir, both individual taxa and communities and separate groups of hydrobionts can be used. Benthic organisms are most often used as bioindicators of the level of water pollution in rivers, but many authors consider it more appropriate to use the periphyton organisms. This is due to the fact that benthic organisms, being under the influence of bottom sediments, are more tolerant to pollution, while periphyton reflects water quality more adequately. The study of the periphyton of the reservoir allows the calculation of information indices reflecting the water condition. The application of the bioindication method makes it possible to identify periods when more frequent sampling is required to establish the compliance of river water with sanitary and hygienic standards.

Multi-dimensional habitat vegetation restoration mode for lake riparian zone, Taihu, China

The riparian zones that were surround bodies of fresh water have been extensively degraded by human influence. Their restoration strength and management are an issue of urgent. Particularly, the knowledge based for the restoration of riparian zone has expanded in recent years. However, progress on a global scale has been limited, because little is known about its complex and diverse functions and structures. A national ecological restoration project of Taihu Lake (China) provided a case study for classifying and restoring the riparian zone. In this work, we quantified the classification of riparian zone, vegetation-zone in the ecotones and a recommended suite of introduced riparian vegetation communities. Taking the structures of the ecotones, soil conditions, vegetation configurations, and anthropogenic disturbances into account, six types of vegetation-zone were used to classify riparian zone, which are as follow: reefs, islands, dokdo–island, island–shore, dike–shore, and shoreland. Then a multi-dimensional habitat vegetation restoration mode for each type based on six vegetation-zones were also recommended. The water ecological quality was developed to a healthy state under this implement. Therefore, results suggest that profound division of habitat-vegetation is important in the modern ecological engineering theories for riparian zone. In order to provide a key parameter for Taihu Lake and other worldwide lakes with similar characteristics, an eco-restoration model and a reconstruction scheme for the vegetation community have been presented. In a conclusion, these recommendations could largely assist further development for lake management.

Impact of hydromorphological pressures on the macrophytes bioindicators of the ecological water quality in Mediterranean rivers

One of the important tools to evaluate the ecological quality of surface water is the Macrophytes indices based on the bioindication capacity of aquatic plants. In Mediterranean rivers (France, Spain, and Portugal), the development of some macrophytes indices like l’Indice Biologique Macrophytes Rivières (IBMR), the biological metric score (BMS), as well as the Fluvial Macrophyte Index (IMF) are founded on the determination of the indicator values of the floristic reference lists.The aim of this study was to test the impact of the eco-Mediterranean differences (from one country to another) on the indicator taxa by comparing the indicator values of the Euro‐ Mediterranean macrophyte indices. With this in mind, we explore the possibility of the introduction of the Euro‐Mediterranean macrophytes-based indices in Morocco (i.e. the hydrological basin of Sebou (HBS)) as a part of a preliminary attempt to develop the first Afro-Mediterranean macrophyte index.We confirm that the ecological amplitude and species optima vary between Mediterranean ecoregions, and indicator taxa differ between countries: There are medium to small correlations between Mediterranean indices: IBMR/BMS (p = 0.000, R2= 0.57), IMF/BMS (p = 0.000, R2= 0.34), and IBMR/IMF (p = 0.000, R2= 0.30). Five species exhibit major differences in indicator values:ZannichelliapalustrisandPotamogetonpectinatushave more eutrophic indicator values in France (IBMR) than in Spain (IMF).Potamogetonnodosus,AmblystegiumripariumandLycopuseuropaeushave broader ecological amplitudes in Portugal (BMS) than in France (IBMR) and in Spain (IMF), where it is restricted to eutrophic conditions. Furthermore, the three indicator systems include different indicator-taxon numbers.The comparison of the HBS elaborated list with the Euro‐Mediterranean indices revealed the low level of common taxa approximately 6.76% of all indicator species used in the French index (IBMR), 10.48% in the Portuguese index (IMF) and 12.38% in the Spanish index (BMS).These results show the inadequacy of the trophic indices approach with the HBS conditions and thus the need for the development of an index based on biotic indices approach.

Reflectance spectra classification for the rapid assessment of water ecological quality in Mediterranean ports

Summary Ports are open systems with direct connection to the sea, therefore any potential impact on port waters may have implications for the health of adjacent marine ecosystems. European WFD addressed ports in the category of Heavily Modified Water Bodies (HMWBs) and promoted implementation of protocols to monitor and improve their ecological status. TRIX index, which incorporates the main variables involved in the trophism of marine ecosystems (Nitrogen, Phosphorus, Chlorophyll a, Dissolved Oxygen), is widely utilized in European coastal areas to evaluate trophic status. The relationships between the variables involved in TRIX computation, particularly Chlorophyll a concentration, and water spectral reflectance provides an alternative method to evaluate the quality and ecological status of the port water. Hyperspectral (380–710 nm) water reflectance data were recorded by a portable radiometric system in five ports from the Western and Eastern Mediterranean Basin. The spectral distance between samples was measured by two metrics using both the original and reduced spectra and was implemented within a hierarchical clustering algorithm. The four spectral classes that emerged from this operation were statistically analysed versus standard water quality descriptors and phytoplankton community features to evaluate the ecological significance of the information obtained. The results indicated a substantial coherence of different indicators with more than 60% of the total TRIX variability is accounted for by the proposed classification of reflectance spectra. This classification is therefore proposed as a promising Rapid Assessment Technique of ports water ecological quality, which can serve as an effective monitoring tool for sustainable management of ports.

Defining a new autoecological trait matrix for French stream benthic diatoms

Autoecological traits of aquatic organisms are well known to provide crucial information on hydrosystems and are good complements to biotic indices for evaluating surface water ecological quality. In France, as in many other European countries, autoecological approaches concerning diatoms are based on a checklist developed in the Netherlands. While this work was pioneering and suited to the conditions of study, ecological indicators developed in such small scales and such specific natural environments often show reduced efficiency when used in other conditions.France is a vast and highly biogeographically diversified region with many situations that are not to be found in the Netherlands, such as limestone substrate rivers and torrents in mountainous areas. Consequently, the elaboration of a better suited autoecological reference system has been long requested by French water managers to support ecological diagnosis.In this study, we elaborated a new autoecological reference system gathering knowledge on environmental optima, tolerance and range values for 809 French diatom taxa, along with an ordinal classification for 7 autoecological traits: water acidity, water mineralisation, oxygen requirements, saprobity, trophic state, organic nitrogen and nitrates. By combining weighted averaging and regression tree techniques we also produced a simple, statistically robust and reproducible approach to study univariate taxa-environment relationships in a given region.This new trait matrix, in addition to providing autoecological attributes for over 200 French diatom taxa that had no correspondence in previous reference systems, also takes into account French specificities such as the scarcity of acidic situations and mineral nitrogen issues. On the basis of this new matrix, 3 autoecological functional groups have been identified in French diatom flora, mainly related to traits linked to anthropogenic disturbance. This revised autoecological classification will provide much more reliable information on French stream benthic diatoms ecology, and should therefore allow better ecological diagnosis if accompanied by rigorous management of synonyms and taxonomic levels.

Flow cytometry analysis of low/high DNA content (LNA/HNA) bacteria as bioindicator of water quality evaluation

Anthropogenic activities such as agriculture, industry and climate change have been creating an enormous pressure on freshwater ecosystems leading to its degradation. Because the Water Framework Directive (WFD; main EU instrument for ecological water quality assessment) is costly and time-consuming, the main goal of this study was to use the scoring by flow cytometry (FCM) of bacterial communities with high DNA content (HNA) and low DNA content (LNA), a fast and easy methodology, as bioindicators. To portray this study, 3 sampling sites of Caima river with different levels of environmental impact (site 1 – no anthropogenic impacted site; site 2 – downstream wastewater treatment plant and site 3 – downstream a deactivated mine) were analysed along the 4 seasons of the year 2017 (winter, spring, summer and autumn). The ecological status of the sampling sites was accessed following the methodology described by WFD and biotic index results obtained for macroinvertebrate and periphyton communities, as well as the BOD5, were compared with the bacterial community scored as HNA and LNA.Bacteria community analysis showed high bacteria density at site 2 corresponding to high amounts of organic input by the wastewater treatment plant. Also, HNA bacteria were found to be in higher quantities at site 2, related to an increase of nutrients, while LNA bacteria were more prominent in river headwater, corresponding to an oligotrophic environment. Correlations between biological indices and bacteria community composition were very strong, showing that bacteria communities may serve as indicators of water quality assessment. Although this FCM technique provide good responses, further investigations are needed to confirm the feasibility of this method.

Chemical mixtures and fluorescence in situ hybridization analysis of natural microbial community in the Tiber river

The Water Framework Directive (WFD) regulates freshwater and coastal water quality assessment in Europe. Chemical and ecological water quality status is based on measurements of chemical pollutants in water and biota together with other indicators such as temperature, nutrients, species compositions (phytoplankton, microalgae, benthos and fish) and hydromorphological conditions. However, in the current strategy a link between the chemical and the ecological status is missing. In the present WFD, no microbiological indicators are foreseen for integrating the different anthropogenic pressures, including mixtures of chemicals, nutrients and temperature changes, to provide a holistic view of the freshwater ecosystem water quality. The main aim of this work was to evaluate if natural microbial populations can be valuable indicators of multiple stressors (e.g. chemical pollutants, temperature, nutrients etc.) to guide preventive and remediation actions by water authorities. A preliminary survey was conducted to identify four sites reflecting a contamination gradient from the source to the mouth of a river suitable to the objectives of the European Marie Curie project, MicroCoKit. The River Tiber (Italy) was selected as a pilot case study to investigate the correlation between bacteria taxa and the chemical status of the river. The main physicochemical parameters, inorganic elements, organic pollutants and natural microbial community composition were assessed at four selected sites corresponding to pristine, agricultural, industrial and urban areas for three consecutive years.The overall chemical results indicated a correspondence between different groups of contaminants and the main contamination sources at the selected sampling points. Phylogenetic analysis of the microbial community analyzed by Fluorescence In Situ Hybridization method (FISH) revealed differences among the four sampling sites which could reflect an adaptive bacterial response to the different anthropogenic pressures.