Specific Pollution Sensitivity Index Research Articles

What do diatom indices indicate? Modeling the specific pollution sensitivity index

Diatoms are commonly used in environmental assessments to detect pollution and eutrophication. The specific pollution sensitivity index (SPI) is one of the most frequently used indices, which assigns scores to diatom taxa based on their sensitivity to pollution. The study analyzed diatom communities in the Duero River basin in Spain to examine the relationship between SPI scores and various limnological variables. A GLM model showed that phosphates, nitrites, and water temperature were the main factors explaining SPI variability. The study also reviews previous results using SPI for water quality monitoring in different world regions, highlighting the role of nutrients in general as major drivers of SPI values worldwide. Overall, the findings reinforce the reliability of SPI as a metric for biological monitoring in various watercourses.

Molecular metrics to monitor ecological status of large rivers: Implementation of diatom DNA metabarcoding in the Joint Danube Survey 4

The Joint Danube Survey (JDS) is a regular transnational survey to monitor the quality of the Danube and its main tributaries, in accordance with the EU Water Framework Directive. During the JDS4 in 2019, conventional methods to monitor selected biological quality elements were complemented with DNA metabarcoding.All together 72 phytobenthos samples were collected along the Danube and its major tributaries within the JDS4, using light microscopy and DNA metabarcoding amplifying a fragment of the rbcL marker gene. The (i) applicability of DNA metabarcoding to identify diatom communities compared to microscopy; (ii) diversity metrics between DNA metabarcoding and microscopy analysis and (iii) the usability of DNA metabarcoding for routine monitoring and assessment of the Danube under future JDS surveys were investigated.Diatom communities resulting from light microscopy and DNA metabarcoding assessments share 26.5% of all taxa which corresponds to 64.3% when considering relative abundances. Discrepancies originate from biases both from metabarcoding, e.g. missing taxa from the reference library, and from microscopy, e.g. overlooking of hardly visible taxa. Microscopy detected more taxa in total but metabarcoding revealed a higher alpha diversity, detecting also very rare taxa in a given sample. Molecular and microscopy based Specific Pollution Sensitivity Index (IPS) values correlated significantly but differences were detected at several sites due to the differences in community composition and the overestimation of large taxa by metabarcoding. Although both methods showed a decreasing trend of IPS along the Danube, the metabarcoding based IPS covered a higher range of quality classes indicating lower values for downstream sites and the tributaries.We suggest that metabarcoding provides a standardisable and efficient tool in biomonitoring, being more distinctive among quality classes than microscopy. Due to the high sequencing depth, it is able to detect a higher diversity on genetic level in a time- and cost-efficient manner that should be implemented in future quality assessment tools. We recommend its use in future biomonitoring surveys, for now, as a complementary method to conventional ones.

Exploration of Applicability of Diatom Indices to Evaluate Water Ecosystem Quality in Tangwang River in Northeast China

The diatom index has been widely used in the evaluation of water ecological quality, but the applicability of the diatom index often varies in different study areas. The accuracy of the evaluation results depends on the applicability of the diatom index, especially when it is not applied to the place where it is created. In order to screen out the diatom index suitable for the evaluation of the water ecological quality of Tangwang River in northeast China, and to identify the factors affecting the accuracy of the diatom index, the community structure and water environment characteristics of 24 sample sites were investigated in Tangwang River in August 2018, and 18 diatom indices were calculated. The discriminative ability of diatom indices was analyzed using the box plot method, and the factors affecting the accuracy of the diatom index were identified by combining Pearson and Spearman correlation analyses. The results show that the discriminability of the Biological Diatom Index (BDI), Specific Pollution Sensitivity Index (IPS), Idse Leclercq (IDSE), Indice Diatomique Artois Picardie (IDAP), Diatom Eutrophication Pollution Index (EPI-D), Trophic Index (Rott TI), European Economic Community Index (CEE), and Watanabe Index (WAT) was the strongest, which could reasonably distinguish the reference group from the lightly damaged group. In general, the water ecological condition of Tangwang River Basin is good in the wet season, and the water ecological quality of about 80% of the sample sites was “moderate” or better. The main factors affecting the evaluation accuracy of the diatom index in Tangwang River Basin are the correlation strength between the diatom index and habitat quality, organic pollution, and nutrients. The coverage of diatom index species had no significant effect on the accuracy of evaluation. In order to reasonably evaluate the aquatic ecological status, it is recommended to use the diatom index, which has a good correlation with the environmental factors in the study area, or to establish a new diatom index based on the diatom community and environmental factors in the study area.

The impact of drought in the Karoo - revisiting diatoms as water quality indicators in the upper reaches of the Great Fish River, Eastern Cape, South Africa

This paper examines the efficacy of diatoms as bioindicators of water quality in the upper reaches of the Great Fish River following a period of reduced flow from drought conditions. Of the five sites, three were sampled three times in an 18 month period while the remaining two were sampled once. As a comparison, one headwater site within Mountain Zebra National Park, situated in the same district, was sampled. A total of 166 diatom taxa belonging to 29 genera were identified. Dominant taxa for the Great Fish River were identified as Amphora pediculus; Epithemia sorex; Nitzschia frustulum; Navicula veneta and Craticula buderi. These species, indicative of high nutrient concentrations and moderately saline to brackish conditions can tolerate low flow conditions. The Generic Diatom Index (GDI), the Specific Pollution sensitivity Index (SPI) the Biological Diatom Index (BDI) and the% Pollution Tolerant Valves (%PTV) – part of the UK Trophic Diatom Index (TDI) were used for interpretation of the results. The indices showed that this river is in poor condition. By comparison the headwater site in the Mountain Zebra National Park had Cocconeis placentula var. euglypta, Achnanthidium minutissimum and Cocconeis placentula var. lineata as dominant species and, using the same indices, the river was classified as in moderate to good condition with respect to water quality. When compared to a previous study (2010 – 2012), these sites showed a shift in dominant species indicating a change in water flow conditions and quality.

Applicability of diatom metabarcoding in the ecological status assessment of Hungarian lotic and soda pan habitats

Diatoms are widely applied in the ecological status assessment of aquatic ecosystems using indices calculated from pollution sensitivity and indicator values of species. Traditional, morphology-based identification of species requires in-depth taxonomic knowledge and expertise. Identifying taxa according to their barcode sequences obtained with high-throughput sequencing (metabarcoding) would be a promising alternative. In this pilot study, we tested the applicability of metabarcoding of benthic diatom assemblages for the ecological status assessment of Hungarian water bodies, comparing its performance to that of morphology-based identification of species. The barcode region of the rbcL gene was investigated in samples from running waters with various trophic states and unique lentic habitats, namely soda pans. For running waters, the Specific Pollution Sensitivity Index (IPS) and for soda pans the H index and the Indice Biologique Diatomées (IBD) were calculated from the morphology- and sequence-based abundances. The ecological quality ratio was determined for running waters. Overall, more infrageneric taxa were found with microscopy than with metabarcoding in the lotic and lentic samples. The correspondence between taxon lists detected by the two methods was relatively low but increased considerably in the case of morphologically dominant taxa. Community composition based on microscopy and DNA sequence analysis showed a significant correlation and was determined by the same main environmental drivers. Morphology-based indices strongly correlated with sequence-based indices. Both aspects indicated the same ecological status class for more than half of the lotic samples. In other cases, a status shift from good to moderate was frequent, a phenomenon that could prove problematic because the Water Framework Directive prescribes intervention for waters with a moderate or worse status. Considering discrepancies between the results obtained with microscopy and metabarcoding, using both methods in parallel could be proposed until the reference database has been suitably updated.

Applicability of diatom metabarcoding in the ecological status assessment of Hungarian lotic and soda pan habitats

Diatoms, eukaryotic algae with silica cell wall have been proved to be reliable bioindicators and are applied in ecological status assessment of aquatic ecosystems using indices calculated from pollution sensitivity and indicator values of species. Traditional method of identification of diatom species is based on morphological features of frustule that requires in-depth taxonomical knowledge and expertise. Metabarcoding that combines barcodes and high-throughput sequencing offers a promising alternative. In this pilot study we tested the applicability of metabarcoding of benthic diatom assemblages for ecological status assessment of water bodies in Hungary comparing its performance to that of morphology-based identification of species. Samples from 78 rivers and streams arranged along a trophic gradient and 14 soda pans representing unique types of habitats were investigated. Sequences of the barcode region of rbcL gene suggested by Vasselon et al. (2017) were acquired revealing 1135 diatom amplicon sequence variants (ASVs) of which 54% could be assigned at species level using Diat.barcode (Rimet et al. 2019) as reference database. Morphological investigation detected more species and intraspecific taxa in the lotic and lentic samples (413 and 78, respectively) than metabarcoding (190 and 75). Correspondence between taxa detected based on morphology and DNA sequences was relatively low (on average 24% in lotic and 26% in lentic samples) but considerably increased (on average 66% and 56%, respectively) when taking into account only the taxa reaching higher than 5% relative abundance in microscopy counting. The differences mainly derived from that a considerable portion (59% and 32%, respectively) of the morphologically identified taxa were not recorded in the reference database. Community structure of samples from both running and standing waters based on microscopy and DNA sequence analysis showed significant correlation as revealed using Mantel test. For rivers and streams diatom index IPS (Specific Pollution Sensitivity Index, (Coste in Cemagref, 1982) for soda pans indices H (Ziemann et al., 2001) and IBD (Indice Biologique Diatomées, Lenoir and Coste, 1996) were calculated from the results of the two aspects. Strong correlation was found between morphology- and sequence-based indices and in about half of the samples, the ecological status class obtained with the two methods coincided. Our results suggest that metabarcoding inheres a great opportunity and could be successfully applied in benthic diatom-based ecological status assessment of Hungarian waters after the reference database is supplemented with taxa frequently occurring in these habitats. References Cemagref, 1982. Etude des méthodes biologiques quantitativesd’appréciation de la qualité des eaux, Rapport Division Qualité des Eaux Lyon. Agence financière de Bassin Rhône-Méditerranée-Corse, Pierre-Bénite, France. Lenoir, A., Coste, M., 1996. Development of a practical diatom index of overall water quality applicable to the French National Water Board Network. Presented at the International symposium, Volksbildungsheim Grilhof Vill, AUT, 17-19 September 1995, Universität Innsbruck, pp. 29–43. Rimet, F., Gusev, E., Kahlert, M., Kelly, M.G., Kulikovskiy, M., Maltsev, Y., Mann, D.G., Pfannkuchen, M., Trobajo, R., Vasselon, V., Zimmermann, J., Bouchez, A., 2019. Diat.barcode, an open-access curated barcode library for diatoms. Sci. Rep. 9, 15116. Vasselon, V., Rimet, F., Tapolczai, K., Bouchez, A., 2017. Assessing ecological status with diatoms DNA metabarcoding: Scaling-up on a WFD monitoring network (Mayotte island, France). Ecol. Indic. 82, 1–12. Ziemann, H., Kies, L., Schulz, C.-J., 2001. Desalinization of running waters: III. Changes in the structure of diatom assemblages caused by a decreasing salt load and changing ion spectra in the river Wipper (Thuringia, Germany). Limnologica 31, 257–280.

Species sensitivity analysis as a tool for interpreting diatom metabarcoding for WFD bioassessment

Recent metabarcoding work in European rivers, including our own studies of Mediterranean rivers in Catalonia (Pérez-Burillo et al. 2020), has shown promising agreement between morphology- (LM) and DNA-based (HTS) assessments of diatom periphyton for the Water Framework Directive. However, in 10 out of the 164 Catalan sites we analysed, the ecological status class was downgraded from “Good”/ “High” with LM to “Moderate”/ “Poor”/ “Bad”by HTS. We call these the “critical” sites and they are especially important because the WFD requires remedial action to be taken by water managers for any river stretch with Moderate or lower status. In order to discover the reasons for downgrading we investigated the contribution of each species to the Indice de Polluosensibilité Spécifique [Specific Pollution-sensitivity Index, IPS] using a “leave-one-out” sensitivity analysis, paying special attention to the critical sites. Discrepancies in IPS between LM and HTS were mainly due to the misidentification and overlooking in LM of a few species, which were better recovered by HTS. This bias was particularly important in the case of Fistulifera saprophila, whose clear underrepresentation in LM was important for explaining 8 out of the 10 critical sites and probably reflected destruction of its very weakly-silicified frustules during sample preparation for LM. Another important bias was brought about by differences between species in the rbcL copy number per cell, which for example affected the relative abundance obtained by HTS for Nitzschia inconspicua and Ulnaria ulna; these species were also identified by the sensitivity analysis as important for the WFD. However, blanket application of a correction factor based on cell volume did not lead to a clear improvement in the agreement between HTS and LM assessments. Only minor IPS discrepancies could be attributed to the incompleteness of the reference library, as most of the abundant and influential species (to the IPS) were well represented there. Finally, we propose that leave-one-out analysis is a valuable method for identifying priority species for isolation and barcoding that are currently not, or only poorly, represented in the DNA reference database.

Applicability of Benthic Diatom Indices Combined with Water Quality Valuation for Dish Lake from Nanjishan Nature Reserve, Lake Poyang

Benthic diatom indices developed in the Europe Union have been widely accepted as indicators of the trophic state and water quality in freshwater ecosystems. In China, most of the benthic diatom-based indices have not been widely tested or evaluated before. For this purpose, the water quality parameters and benthic diatoms community structures at 20 sample sites in the dish lake of Nanjishan Nature Reserve in Poyang Lake were investigated in this study and 18 widely-applied diatom indices were established. The statistical results indicated that most water quality parameters including Total Nitrogen (TN), Total Phosphorus (TP), ammonia nitrogen (NH4+), Chemical Oxygen Demand (COD) and Chlorophyll (Chl) were highly correlated with each other at a confidence level of 0.05. Water quality sampling sites from 8 lakes could be classified into 4 groups based on the integrated comprehensive scores using principal components analysis (PCA). Monitoring sites could also be divided into 4 groups based on clustering analysis with hierarchical methods for diatom dominant species in 20 sampling sites. According to the status of water ecological health recognition and box plot analysis in different water quality groups and diatom dominant species groups, only 3 diatom indices including the Biological Diatom Index (IBD), Specific Pollution Sensitivity Index (IPS) and Louis Leclercq Diatom Index (IDSE) demonstrated good evaluation suitability and good correlation within different water quality grades at the final stage. The above results revealed that IBD, IPS and IDSE were the most suitable diatom indices for the water quality evaluation of the dish lake in the Nanjishan Nature Reserve, Lake Poyang.

Benthic diatom-based indices and isotopic biomonitoring of nitrogen pollution in a warm temperate Austral river system

Rivers are impacted by pollutants from anthropogenic activities such as urbanisation and agricultural practices. Whilst point source pollution has been widely studied and in some cases remediated, non-point pollutant sources remain pervasive, particularly in developing countries that lack economic and human specialist capacity. Monitoring of pollution levels in many regions is additionally challenged by a lack of robust indicators for nitrogen inputs, however, diatom community indices and analysis of variation in microphytobenthos (MBP) stable isotope analysis variations have potential. The present study investigates variations and utilities in benthic diatom indices and MPB δ15N along different river sections (n = 31) of an austral river between two seasons (wet and dry), testing for relationships with key environmental variables (physical, water and sediment), in the context of N monitoring. One hundred and eighteen diatom taxa belonging to 36 genera were identified, with physical (water flow), water (nitrate, P and total dissolved solids) and sediment (B, Ca, Cr, Na, N, P, SOM, Pb and Zn) variables correlating to one or more of the 12 diatom indices presented. In particular, Biological Diatom Index, Biological Index of Water Quality, Central Economic Community, Index of Artois-Picardie Diatom (IDAP) and Sládeček's Index were strongly explained by sediment variables, whilst Descy's Pollution Index and Schiefele and Schreiner's Index were explained by water and physical variables. Whilst MPB δ15N were within the “no impact” level in the wet and dry seasons at reference (i.e. unpolluted) sites, all sites located in agricultural or urban areas, and downstream of sewage discharges, had a wider range that encompassed increasing organic impacts (“inorganic impacts” to high “organic impacts”). Temperature and turbidity (negative), as well as dissolved oxygen, waterway width and depth (positive), significantly affected MPB δ15N, whilst effects of chemistry variables were less apparent. Overall, we found that MPB δ15N signatures were significantly correlated with Trophic Diatom Index, the Specific Pollution Sensitivity Index and the Artois-Picardie Diatom Index, suggesting the utility of diatoms and MPB δ15N in assessments of aquatic pollution. In turn, MPB δ15N values are strong indicators of N pollution across spatial and seasonal gradients. Thus, the results showed the effects of sediment variables on diatoms to be strong, indicating that sediment rather than water characteristics more strongly structure diatom communities. Thus, sediment variables should be sampled when conducting bioassessment studies.

Use of Diatoms in Monitoring the Sakarya River Basin, Turkey

The Sakarya River basin is one of the largest basins in Turkey, and encompasses the Kocaeli, Düzce, Sakarya, Bursa, Bilecik, Bolu, Kütahya, Eskişehir, Ankara, Afyon, and Konya provinces. In this study, the water quality status of the basin was investigated using 18 diatom indices, calculated in Omnidia software. For this purpose, a total of 46 stations were surveyed in the rivers and streams of the basin in May 2018. As a result, 41 of 195 diatom taxa were found to be the most frequent (>10% share in assemblage). According to Detrented Correspondence Analysis (DCA), three subgroups were described as the spring section, Ankara and Polatlı section, and lowland section. The river basin quality was evaluated as moderate or lower quality status, while only a few sites had good status. The diatom index scores showed that the Descy’s Index (DES), Pampean Diatom Index (IDP), Artois-Picardie Diatom Index (IDAP), and Specific Pollution Sensitivity Index (IPS) appear best suited to water quality assessment in this area, showing the largest number of significantly important correlation with environmental variables.

Benthic diatom community dynamics in Mediterranean intermittent streams: Effects of water availability and their potential as indicators of dry-phase ecological status

The study of intermittent rivers is a critical and timely issue due to their worldwide increase, triggered by several causes including climate change. The need to understand the response of intermittent river biota to water intermittency led us to conduct this study using benthic diatoms collected in southern Portugal. Benthic diatoms were explored in terms of assemblages, diversity indices, the Specific Pollution Sensitivity (SPI) Index, functional metrics (i.e. ecological guilds and life-forms) and conservation status. We verified that changes in water physico-chemical characteristics were highly controlled by flow intermittency, which in turn is directly linked to meteorological variables (air temperature and precipitation). Changes in diatom assemblages reflect the aquatic regime of sites, changes in aquatic states through time and mesohabitats (dry biofilm, samples collected in pools or under flowing conditions). Species richness, on the other hand, did not reflect these differences, whilst Shannon diversity and Pielou's Evenness indices only reflected mesohabitat differences. The SPI distinguished sampling periods, and mesohabitats. The relative abundance of ecological guilds changed with aquatic states, with the low-profile guild dominating in eurheic and arheic conditions (except during Summer), being replaced by motile taxa in summer arheic conditions, reflecting increases in nutrient and siltation. The hypothesis that benthic diatom assemblages in dry biofilm can be used as an indicator of ecological status during the dry-phase was validated, since no differences between the Ecological Quality Ratio determined in dry biofilm collected in Summer 2017 and the previous Spring 2017 in flowing water. A method is proposed for diatom sampling in dry biofilm, contributing to an integrated ecological status evaluation, which considers the dry-phase and enhances the reach of biomonitoring programs.

Effect of Land Use on the Benthic Diatom Community of the Danube River in the Region of Budapest

(1) Urbanization significantly influences the ecosystems of rivers in various ways, including the so-called loading effect of wastewater production. Benthic diatoms are used in ecological status assessments of waters. Beside species composition, traits can be used as indicators. We aimed to evaluate how the loading of the large city of Budapest manifests in the physico-chemical variables of the River Danube and what species composition and trait response this loading results in for the benthic diatom communities. (2) Weekly samplings were performed at points upstream and downstream of Budapest on both riverbanks. Samples were compared, based on general physical-chemical variables and the concentration of thirty-four elements, as well as species composition and seven traits of species of diatom communities. Ecological status was assessed using the Specific Pollution Sensitivity Index (IPS). (3) Only a few measured environmental variables showed differences between the sampling points, suggesting that the nutrient loading has significantly decreased due to the installation of several efficiently working wastewater treatment plants since the introduction of the European Union Water Framework Directive. In contrast, the species composition and traits of species showed the effect of land use. Benthic diatoms indicate the environmental changes caused by land use in the longer-term, while chemical measurements reflect instantaneous status.

Vertical distribution of benthic diatoms in a large reservoir (Alqueva, Southern Portugal) during thermal stratification

Freshwater diatom communities are known to respond to a wide range of environmental factors, however, the depth gradient is usually neglected and few studies are available, especially in large reservoirs. During the ALqueva hydro-meteorological EXperiment (ALEX) field campaign, diatom communities were studied in the margins and in three platforms (from the surface to the bottom of the reservoir) located in the limnetic zone of the Alqueva reservoir, one of the largest artificial lakes in western Europe. A detailed meteorological and physico-chemical characterization of the reservoir was carried out from June to September in Summer 2014, when the reservoir was stratified, to relate these variables with diatom assemblages. Despite the large dimensions of the reservoir, no differences in the water physico-chemical characteristics and diatom descriptors were detected among platforms. Small changes in diatom assemblages, ecological guilds, taxa richness and Shannon diversity index were observed between sampling campaigns. Nevertheless, differences in diatoms were detected along a depth gradient, both in terms of diatom assemblages and ecological guilds. Taxa richness, Shannon diversity index, Pielou's evenness and Specific Pollution sensitivity Index (SPI) also differed with depth, with the lowest values of all indices detected at surface samples, increasing with depth, reaching the highest values at 20 m for taxa richness, Shannon diversity and Pielou's evenness indices.

Effects of water ecological environment on benthic algae in a water source reservoir

Several benthic plants and animals live in lakes and reservoirs. Benthic algae, mostly diatoms, can reflect the quality of the water environment. The indicative function of water quality by diatom community and basic principle of diatoms in-dexmethod was described. This paper investigates the benthic algal community in a water reservoir basin.in flood season (July) and non-flood season (November) respectively. A total of 129 species of benthic diatoms were collected in flood season (July) and non-flood season (November). By analyzing the generic index of Trophic Diatom Index (TDI), Index of Biological Diatom (IBD) and Specific Pollution Sensitivity Index (IPS) the status of aquatic ecological environment in this reservoir was evaluated, which indicates that the water quality of reservoir area is better.

Deceptive ecological status of urban streams and rivers—evidence from diatom indices

AbstractUrbanization directly affects the ecological status of streams and rivers: Their beds and drainage basins are often heavily transformed and their habitat conditions disturbed. The aim of the study was to evaluate the extent of human impact in streams in the city of Łódź, Central Poland (~700,000 inhabitants), by pattern recognition analysis of benthic diatom assemblage samples using a Kohonen artificial neural network, principal component analysis, and indicator species analysis. The study also determined the ecological status of the streams using five diatom indices: Multimetric Diatom Index, Specific Pollution Sensitivity Index, Generic Diatom Index, Biological Diatom Index, and Trophic Diatom Index. The samples demonstrated considerable variation in ecological status. Examples of poor and bad ecological status were observed, clearly resulting from strong human pressure; however, good status and moderate status were also recorded, both at natural sites and, unexpectedly, those which were severely transformed, whose beds were covered with concrete and which were located downstream from combined sewer overflows. Such sites demonstrated high water conductivity of up to 1440 μS/cm, but this was accompanied by other more favorable conditions: The water flowed from upstream stretches enclosed in downtown underground canals with a fast current, low water temperature, and high average concentration of dissolved oxygen (approximately 10 mg/dm3). These conditions had a mitigating effect, shaping the diatom assemblages to a specific form with the highest species richness and the highest number of indicator taxa observed in the study. In summary, the hydromorphological transformation of streambeds may result in seemingly good ecological status at heavily degraded sites. Therefore, conclusions based on diatom‐based biomonitoring of urban streams and rivers should be drawn with caution.

Use of diatom indices to categorise impacts on and recovery of a floodplain system in South Africa

The trophic status of the Ramsar-accredited Nyl River floodplain, which is stressed by sewage treatment effluents, and its ability to restore normal conditions, were assessed in 2014–2015 using diatoms as biological indicators. The Trophic Diatom Index, Specific Pollution Sensitivity Index and the Generic Diatom Index were used to characterise water quality under high and low flow conditions in 2014. An additional survey was conducted in May 2015, following an accidental sulphuric acid spill above the Sewage Treatment Works (STW). Significant linear correlations were identified between physico-chemical parameters and the indices, as well as between the three indices themselves, validating their use to infer water quality. Water quality deteriorated from the source of the Klein Nyl River, especially at the STW, but improved within the Nylsvley Nature Reserve wetland sampling site (NYL).

Diatom diversity and water quality of a suburban stream: a case study of the Rzeszów city in SE Poland

Abstract The aim of this work was to investigate the diversity of diatom assemblages developed in the Przyrwa stream, to assess water quality based on benthic diatoms and to make an attempt at the identification of physicochemical factors having the greatest impact on the differentiation of diatom assemblages. Studies were conducted in 2011-2012 on the Przyrwa stream, a left-side tributary of the Wisłok River flowing through the city of Rzeszów and with its spring section located on the borders of the city. A total of 259 diatom taxa were identified in the Przyrwa stream during three studied seasons. At all investigated sites, the most abundant population consisted of Ulnaria ulna (Nitzsch) Compère, Cocconeis pediculus Ehrenb., Achnanthidium minutissimum (Kütz.) Czarnecki var. minutissimum, Navicula gregaria Donkin, Planothidium frequentissimum (Lange-Bert.) Lange-Bert., P. lanceolatum (Brébisson) Lange-Bert., Navicula lanceolata (C. Agardh) Ehrenb., Amphora pediculus (Kütz.) Grunow, Eolimna minima, (Grunow) Lange-Bert., Melosira varians C. Agardh and Cyclotella meneghiniana Kütz. Based on IPS (Specific Pollution Sensitivity Index) and GDI (Generic Diatom Index) indices, the ecological status of the Przyrwa stream was assessed as moderate to poor (mostly III-IV class of water quality), while the TDI (Trophic Diatom Index) index indicated a poor to bad ecological status (mainly IV-V class of water quality).

Diatoms as water quality indicators in the upper reaches of the Great Fish River, Eastern Cape, South Africa

This study focused on the spring-fed upper reaches of the economically important Great Fish River with the aim of determining if diatoms could be used for biomonitoring in semi-arid conditions in southern Africa. Five sites were monitored monthly from 2010 to 2012. Of the 269 diatom taxa belonging to 51 genera identified, the dominant taxa were mostly those considered to be pollution-tolerant: Amphora pediculus, Craticula buderi, Fragilaria biceps, Nitzschia frustulum, Nitzschia paleacea, Planothidium lanceolatum and Rhopalodia gibba. A number of diatom-based numerical indices were used to infer water quality, including the generic diatom index, the specific pollution sensitivity index, the biological diatom index, and percentage pollution-tolerant valves, which forms part of the UK trophic diatom index. All index scores showed the Great Fish River to be impacted, and showed significant correlations of diatom species abundance with pH, NO3-N, electrical conductivity, NH4-N and CaCO3. Analysis revealed EC and NO3-N as the main environmental drivers affecting diatom community composition, followed by pH and PO4-P. The percentage of diatom deformities at all sites was high, at 3.5%. Diatom indices showed the river to be impacted by decades of agricultural activity, which was confirmed by chemical water analysis. Thus diatom indices can be used for biomonitoring in semi-arid areas.

Using benthic diatom assemblages to assess human impacts on streams across a rural to urban gradient.

Benthic diatom assemblages on the natural substrata were investigated at 21 sites of the Ganhe River watershed (China) once per season and in addition, early spring in 2013. A total of 487 diatom taxa from 36 genera were identified during five investigations. The assemblages were dominated by Achnanthidium minutissimum (Kützing) Czarnecki and Cocconeis placentula in the rural reach, whereas Navicula, Nitzschia, and Gomphonema species were characteristic of urbanized sites. Our results suggest that biodiversity was positively related to high nutrient levels and strongly negatively related to diatom-based indices. The periphyton biomass (expressed as chlorophyll a and ash-free dry mass) was not related to water quality. Canonical correspondence analysis (CCA) showed that the nutrient concentration gradient was the most important factor that affected the diatom assemblage composition and species distribution. The diatom-based indices (specific pollution sensitivity index (IPS), biological diatom index (IBD), and trophic diatom index (TDI)) were significantly positively correlated with water quality and are adequate for use in China. Slight changes in the biodiversity and diatom-based indices followed a temporal pattern. The species composition was less related to the season or hydrological characteristics of the river but more strongly related to differences in the trophic status. In this region, urbanization masked the impact of rural land use on benthic diatoms. The research will expand the understanding of using benthic diatom assemblages for water quality monitoring in urban streams and improve watershed-scale management and conservation efforts in the Ganhe River, China.

Diatoms in the biological assessment of the ecological state of waters using the Czarna Staszowska River as an example

Abstract The object of the present research was the Czarna Staszowska River, which is located in south-eastern Poland and which is a left tributary of the upper Vistula River. The length of the river is 61 km and its sources are situated in the Świętokrzyskie Mountains. The river flows across an area covered by Mesozoic rocks, mostly carbonate and sulfate ones. The upper and middle course of the river is of natural character, while increased pollution occurs downstream of the Chańcza Reservoir. In the present study, the water quality of the Czarna Staszowska is investigated in the pure and polluted sections using diatom indices, such as IO − Diatom Index, IPS − Specific Pollution Sensitivity Index, GDI − Generic Diatom Index and TDI − Trophic Diatom Index. In the four river sections distinguished on the basis of the hydrology and the degree of water pollution, the occurrence of different indicator species was determined in the respective diatom assemblages. Indicator species were determined, i.e. characteristic of oligosaprobic and mesosaprobic, limestone and silicon-rich waters. Also taxa indicating an increased trophic status of the river (occurring in its polluted sections) were identified.