Search

The studies conducted in this research work emphasizes on the use of Sensitive Pollution Index (IPS) based on epilithic diatom community towards evaluation of water quality in Shkodra Lake. Benthic diatoms are the groups of diatoms, which are less vulnerable to disturbances be they of a physical, chemical or other nature thus making the convenient indices for the ecosystem under consideration. Benthic diatoms were gathered from five sampling sites situated in proximity to the shores of Shkodra Lake, including: Shterbeq (Sh1), which is close to the Montenegro border Kompleksi Hysaj (Sh2), Vraka (Sh3), Shiroka (Sh4) and Zogaj (Sh5). The findings reveal that the water quality is not uniform over the space meaning that there are some human socio-economic activities and some natural factors that are affecting the ecological state of the lake. In total, two field trips were conducted in Decembre 2023 and May 2024. It is often found that, as compared to diatoms, chemical indicators of water quality are of less reproductive value. Nevertheless, because their communities can assimilate rising concentrations of both organic as well as inorganic chemical constituents, they are often preferred for in situ biomonitoring. This study shows that some significant shifts in species composition can be detected in relation to changes in dominance patterns of specific species from Shkodra Lake’s aquatic communities. The identified dominant species include a total of 92 diatom species, including most dominant species like as: Cocconeis placentula var. lineata (Ehrenberg) Van Heurck, Cymbella affinis Kützing agg., Eunotia glacialis F. Meister 1912, Gomphonema olivaceum (Hornemann) Brébisson var. olivaceum, Cyclotella ocellata Pantocsek, Aulacoseira granulata (Ehrenberg) Simonsen, Fragilaria incognita E. Reichardt, Gomphonema truncatum Ehr., Nitzschia dissipata (Kützing), etc. About 88 species belong pennate diatoms and four belong centric diatoms. The proceedings of this research include the application of the IPS index and water quality assessment for different locations in Shkodra Lake, proving the detail of the water quality assessment conducting by mean of the IPS index and the crucial role diatoms play in monitoring freshwaters (Prygiel J. and Coste M, 1993; Miho et. al., 2010)). In our study, the IPS (sensitive pollution index) has been calculated also to show the connections between BOD, COD, total and P determination., Nitrates, Nitrites, pH, etc. The Sensitive Pollution Index fluctuated between moderate and very good quality but only Shiroka station was classify as Poor quality. [ABSTRACT FROM AUTHOR]

The aim of this study is to determine the epilithic diatom flora of stations exposed to pollutants of different characteristics, to test the relationships of these diatoms with water quality and the suitability of environmental quality indicators, and to determine different indicators of various quality pollutants for the rapid assessment of ecological pollution. Additionally, determining the ecological impact of both industrial and domestic waste on the reservoir in the region and determining whether the diatom community changes when exposed to various pollutants (including potential mortality), especially its role as an indicator of metal pollution; Samples taken from stations where domestic and industrial wastes were discharged with different chemical properties were evaluated and investigated. A total of 100 species were identified for Bacillariophyta. Although there was no significant change in the number of the species among the stations, significant changes were observed in the community structure. While Achnanthidium minutissimum, Fragilaria capucina, Gomphonema parvulum, Nitzschia palea and Surirella angustatum were the dominant diatoms in the impermeable artificial pool where the industrial wastewater of the factory was collected, Nitzschia amphibia, N. palea, N. recta and Ulnaria ulna were the dominant diatoms of the station where domestic wastewater was discharged. In the dam area where domestic wastewater is discharged, Fragilaria capucina Ulnaria ulna and Diatoma vulgaris are the dominant diatoms. Achnanthidium minutissimum, Gomphonema parvulum Navicula cinta and Nitzschia amphibia, N. angustata were the dominant diatoms of the station where both domestic and industrial wastewater was discharged. It was determined that benthic diatoms responded to different types of waste by changing their species composition, and that the change in the benthic community was not due to seasonal differences in stations under the influence of pollutants with different chemical properties. Diatom taxa which are known to tolerate metal concentrations, diatom diversities, and teratologies were determined.

Copyright of ESPOCH Congresses: The Ecuadorian Journal of S.T.E.A.M. is the property of Knowledge E DMCC and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Diatoms in two springs with different surrounding land use in the Karoo compared. • Diatom indices GDI, SPI,BDI and%PTV were used to evaluate water quality. • Diatom species and indices in Great Fish River compared to historical data. • Indices at headwater site reduced ecological classification compared to previous study. 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. [ABSTRACT FROM AUTHOR]

In the Basin of Mexico, one of the most important economic regions in the country with over 22 million inhabitants, peri-urban streams have been transformed into sewers, drains, and pipes to avoid flooding or unsanitary conditions; the change affects not only the ecosystem's goods and services but also the aquatic communities that support the natural ecological processes. We aimed to develop a diatom-based diagnosis of the ecological quality of these aquatic ecosystems through the study of epilithic diatom response to regional environmental gradients. Samples of epilithic diatoms and water were collected in 45 sites representing 12 perennial streams, and multivariate analyses were performed on environmental and biological data. The ecological quality gradient to which diatoms responded was related to oxygen saturation, soluble reactive phosphorous, dissolved inorganic nitrogen, and hydromorphological quality. Three species groups were recognized according to their ecological preferences along CCA1 axis, indicators of high and low ecological quality, and tolerant species. By assigning an indicator value to each species group, we calculated the DEQI using the formula adapted from Pantle and Buck, indicating five different ecological quality classes. This index is proposed for complementing the ecological quality evaluation as a biological metric that responds to multiple regional stressors of the structure and function of these peri-urban streams in the Basin of Mexico. [ABSTRACT FROM AUTHOR]

The epilithic diatoms of a periurban watercourse of Casablanca city (Bouskoura stream) were studied from samples taken in 8 stations (distributed in the upstream-downstream direction) for two years (August 2015-July 2017). The recorded diatomic flora consists of 54 species corresponding to 27 genera and belonging to 5 main families: Monoraphids, Naviculaceae, Nitzschiaceae, Araphids and Surirellaceae. This flora is predominantly alkaliphile and characterizes β-mesosaprobe to polysaprobes and eutrophic to hypereutrophic media. Responses assemblage to natural and anthropogenic disturbances were analyzed. Diatom assemblages structure analysis shows that downstream of this watercourse, where pollution is intense, the abundances of pollosensitive taxa such as Achnanthes minutissima, Cymbella affinis are low or even nulls and we are witnessing the appearance of polysaprobe forms such as Nitzschia palea, Nitzschia capitellata and Nitzschia frustulum that tolerate rich environments in organic matter or highly polluted. Spatial variation in species diversity could not highlight changes in water quality at the prospected sites; on the other hand, the change in the percentage of pollutant-tolerant taxa (PTV) revealed the full extent of the alteration due to gradual nutrient and organic matter inputs into the Bouskoura watercourse. In addition, the correlation obtained between this index and the organic pollution index (IPO) is highly significant. Principal component analysis (PCA) highlighted taxonomic differences between stations. The results obtained in this work have emphasized the importance of diatoms as a bioindicator of the health status of this periurban watercourse. [ABSTRACT FROM AUTHOR]

Great Lake is the largest of 14 lakes situated in Lurë National Park, in the eastern part of the Lurë Mountains, Albania. To characterize lake ecological status, epiphytic and epilithic diatom samples were collected from the lakeshore in summer 2005, 2013, and 2017. However, in 2017 no macrophytes were present, such that only epilithic diatom samples could be collected. After laboratory analysis, 52 diatom taxa were identified in July 2005, 67 in June 2013, 111 in August 2013, and 126 in August 2017. The genera Diatoma, Epithemia, Fragilaria, and Surirella were not recorded in 2017, contrary to previous years. We applied two diatom indices to asses the ecological status of the Great Lake, IPS (Indice de Polluo–sensibilité), and TDIL (Trophic Diatom Index for lakes). The IPS index indicated very good water quality in all years, while the TDIL indicated moderate water quality in 2005 and 2013 and good water quality in 2017. Because more species have indicator values for calculating the IPS than the TDIL (valve number used to calculate the IPS was above 95%, while for TDIL was below 50% of 400 counted valves), the IPS may be a more promising tool for bioindication of lakes in Albania according to the demands of the Water Framework Directive. [ABSTRACT FROM AUTHOR]

The investigation of the Despotovica River was carried out in April 2017 with the aim to provide an indicative ecological status assessment. Phytobenthos and aquatic macroinvertebrate communities were followed as well as physico-chemical parameters of water. Ecological status assessment is given based on biological (epilithic diatoms and macroinvertebrates) and supporting physico-chemical water quality elements, according to the Serbian National regulation on parameters of ecological and chemical status of surface waters and parameters of chemical and quantitative status of ground waters. The ecological status was determined by the worst evaluated water quality element. Based on the analysis of investigated parameters of biological and physico-chemical water quality elements, the indicative ecological status of the Despotovica River could be assessed as bad (class V), which is the result of the river's load of organic and inorganic origin but also of heavy metals.

Epilithic diatom community of Tolmia Stream, as well as physicochemical properties of the stream were studied through samples collected from the specified 4 stations in monthly periods for one year. 70 species from 21 genera were identified in the study. In epilithon in the stations. Navicula spp. (16 taxa) was the most remarkable genus in terms of both number of species and the number of individuals from species and this was followed by Cymbella (13 taxa) and Nitzschia (9 taxa). The water quality in the Tolmia stream varied at different stations based on levels of pollution. The epilithic diatom communities responded to changes in the aquatic environment. Dominant species had variation among the stations. Dominant species of the station 1 were Cocconeis placentula, Diatoma vulgaris, Cymbella afflnis and Gomphonema olivaceum. Navicula eiyptocephala, C. minuta, Ulnana ulna, Nitzschia amphibia, and N thermalis were dominant diatoms of the stations 2 and 3. Dominant diatoms of the station 4 were Achnanthidium minutissimum, N palea, Gomphonema pairulum, and Surirella an gust at a. diversity of diatoms also varied in all stations in parallel to water quality. Also, station 4 in Beyler Brook in which wastes of 1st and 2nd Organized industry zones are discharged joins to Tolmia stream. We concluded that Tolmia stream has a water quality gradient and this led to apparent variances in species composition of diatom across the stream. The results have confirmed that epilithic diatoms are crucial biological indicators to evaluate ecological quality of Tolmia stream. [ABSTRACT FROM AUTHOR]

Epilithic diatoms are frequently recommended for river biomonitoring, while much less emphasis is placed on epiphytic communities. This study considers use of epiphytic and epilithic diatom communities from the Raška River in biomonitoring. A total of 212 diatom taxa were recorded in both communities. Dominant diatoms were Achnanthidium minutissimum (Kützing) Czarnecki, A. affine (Grunow) Czarnecki, A. subatomus (Hustedt) Lange-Bertalot, Amphora pediculus (Kützing) Grunow, Diatoma vulgaris Bory, Gomphonema tergestinum (Grunow) Fricke, Cocconeis placentula var. lineata (Ehrenberg) Van Heurck, Melosira varians Agardh and Navicula tripunctata (Müller) Bory. Redundancy analysis (RDA) was used to detect the relationships between diatoms, some environmental factors and sampling sites. Diatoms of the epiphytic community showed a clearly grouping in relation to the sampling sites as compared with diatoms of the epilithic community. Species common to both communities showed a similar correlation with some environmental variables (BOD, pH, NH4+, TP, NO3− and conductivity), with three exceptions (Diatoma vulgaris, Cymbella compacta, and Encyonema silesiacum). Pearson’s correlation coefficient showed correlation between selected environmental variables and diatom indices calculated using OMNIDIA 6.2 software (TDI, IPS, CEE, GENRE, TID, SID, SHE and IDSE/5). Diatoms of the epiphytic community are more clearly clustered in relation to the sampling sites as compared with diatoms of the epilithic community. According to our results there is still “place” in biomonitoring for epiphytic community. The present study highlights the necessity of sampling both epiphytic and epilithic communities because substrate specificity could play important role in biomonitoring. [ABSTRACT FROM AUTHOR]

Patterns of epilithic diatom species distribution in relation to environmental variables from 12 sampling sites on the main stream and some of its tributaries in the Nilüfer Stream Basin were determined using multivariate statistical techniques. The stream basin has been heavily influenced by anthropogenic effects. The upper part of the basin that is distant from pollution sources mostly has a spring water quality, while the lower part where the stream flows through the urban area and receives domestic and industrial wastewater has a quite low quality. Ordination techniques using both diatom taxa and 21 environmental variables revealed non- to slightly polluted upper basin sites and highly polluted lower basin sites along the stream. The results showed that the stream catchment is polluted gradually from upstream to downstream and that most of the downstream sites have very low water quality especially in summer months. A total of 134 epilithic diatom taxa belonging to 50 genera were recorded for 12 sample sites. Partial CCA results indicated that water temperature (T), discharge (Q), and total phosphorus (TP) were the most important variables affecting the distribution of diatom species. Unpolluted or slightly polluted upper basin sites were dominated by Achnanthidium minutissimum, Cocconeis placentula var. euglypta, Gomphonema olivaceum, and Navicula tripunctata. Highly polluted lower basin sites were characterized by high levels of organic and inorganic matters and low dissolved oxygen (DO) values. Species widespread in the highly polluted lower basin sites such as Nitzschia umbonata, Nitzschia amphibia, Nitzschia capitellata, Nitzschia palea, Nitzschia paleacea, Luticola mutica, and Stephanodiscus niagarae were mostly related to pollution indicator variables such as ammonium nitrogen (NH -N), sodium (Na), total phosphorus (TP), and total organic matter (TOM). [ABSTRACT FROM AUTHOR]

The Kungsträdgården metro station is an artificial and urban subsurface environment illuminated with artificial light. Its ecosystem is almost completely unknown and as a first step to better understand the biology and rock wall habitats the diatom flora was investigated. A total of 12 species were found growing on the rock walls of Kungsträdgården metro station. The results show the diatom flora in Kungsträdgården to be dominated by e.g. Diadesmis contenta, Diadesmis perpusilla, Pinnularia appendiculata, Nitzschia amphibia, Nitzschia sinuata and Diploneis ovalis. One species, Caloneis cf. aerophila, has never been reported from Sweden before. Significant differences in the species composition between the sampling sites indicate Kungsträdgården metro station to be a heterogeneous habitat that provides different microhabitats.

Copyright of Works of the Faculty of Forestry University of Sarajevo is the property of Faculty of Forestry University of Sarajevo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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 lanceolatumandRhopalodia 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. [ABSTRACT FROM AUTHOR]

This study explores the relationships between environmental factors and the distribution of epilithic diatoms in 161 estuaries of three coastal areas on the Korean peninsula. We investigated epilithic diatoms, water quality, and land use in the vicinities of the estuaries during the months of May 2012, 2013 and 2014, because Korea is relatively free from the influences of rainfall at that time of year. We recorded 327 diatom taxa from the study sites, and the assemblage was dominated by members of the Naviculaceae. Bacillariaceae accounted for the largest proportion of diatoms, and Nitzschia inconspicua (18%) and N. frustulum (9.6%) were the most dominant species. A cluster analysis based on epilithic diatom abundance suggested that the epilithic diatom communities of Korean estuaries can be classified into four large groups (G) according to geography, as follows: Ia-the East Sea watershed, Ib-the eastern watershed of the South Sea, IIa-the West Sea watershed, and IIb-the western watershed of the South Sea. The former two groups, Ia and Ib, showed higher proportions of forest land cover and use, higher species occurrence, lower salinity, lower turbidity, and lower concentrations of nutrients than the latter two groups, while the latter groups, IIa and IIb, had higher proportions of agricultural land cover and use, higher electrical conductivity, higher turbidity, higher concentrations of nutrients, and lower species occurrence. The environmental factors underlying the distribution of epilithic diatoms, representative of each region, are as follows: dissolved oxygen and forest land cover and use for Reimeria sinuate and Rhoicosphenia abbreviate of the East Sea (ES), salinity and turbidity for Tabularia fasciculate of the West Sea (WS), and biochemical oxygen demand (BOD) and nutrients for Cyclotella meneghiniana of the WS. On the other hand, the most influential environmental factors affecting the occurrence of indicator species showing the highest indicator values (>60%) of each group were electrical conductivity for Navicula saprophila and Reimeria sinuate of Ia, and turbidity for Encyonema minutum of IIa. Collectively, the distribution of epilithic diatom communities inhabiting Korean estuaries are determined by geographical factors and water quality, which are in turn influenced by land cover and use, and which differ from east to west. [ABSTRACT FROM AUTHOR]

To monitor water quality and investigate relationships between downstream nutrient increases and diatom communities in the Pardo River Basin, Brazil, water and diatom samples were collected between 2005 and 2009. There were significant differences in diatom community composition among all river zones, with the greatest differences found between the upper and lower reaches. Significant changes were detected in relative abundances of diatom species and spatial structuring was evident. Dissolved oxygen, phosphates, turbidity, Eicherichia coli, and total dissolved solids were the most important variables shaping diatom communities, characterizing an organic pollution and eutrophication gradient. However, the hypothesis of sensitive species prevailing upstream and their gradual downstream replacement for more tolerant species was not confirmed because shifts in relative abundances of the same group of species in both the upper and lower reaches of the rivers were identified. [ABSTRACT FROM AUTHOR]

This research aimed at developing the Trophic Water Quality Index (TWQI) for subtropical temperate Brazilian lotic systems based on a review of the indicative values of diatom species obtained using multivariate analysis techniques and considering the environmental gradient defined by a series of measured physical, chemical, and microbiological variables. Sampling was conducted from 2005 to 2009 in the Pardo River Hydrographic Basin, Rio Grande do Sul (RS), Brazil, and in the Andreas Stream Hydrographic Basin, RS, from 2012 to 2013. A total of 140 biological samples and 211 abiotic samples were collected. Data were analyzed by cluster analysis based on the Ward method and canonical correspondence analysis (CCA). The results indicated that total phosphate, turbidity, ammonia nitrogen, electrical conductivity, dissolved oxygen, and thermotolerant coliforms showed a significant correlation with the sample ordination made by CCA, in relation to a gradient of eutrophication. Eutrophication was operationally defined in a broad sense, including the problem of organic pollution and eutrophication of the water. The determination of the different tolerance degrees to eutrophication of the diatom taxa was used to assign trophic values of 1, 2.5, and 4 to species, corresponding to levels of low, medium, and high tolerance, respectively. By using the trophic values obtained for each diatom species, the TWQI constituted a new technological tool for environmental monitoring studies and showed a consistent, robust, and objective database for water quality assessment in subtropical temperate Brazilian lotic systems. [ABSTRACT FROM AUTHOR]

Epilithic diatom communities were sampled every two weeks from February 2001 to February 2002 at three sites in the lower Han River (LHR), South Korea, to investigate how epilithic diatom communities reflected longitudinal gradients in environmental quality measures. The water quality in the LHR differed between the rainy and dry seasons and also varied at different sites according to levels of pollution. The epilithic diatom communities responded to changes in the aquatic environment and hydrological characteristics. There were few predominant diatom species during the rainy season, and they were found at lower concentrations than in the dry season because of the high current velocities caused by heavy rainfall. The predominant species at the three study sites in the LHR were different because of the effects of eutrophication gradients.Cocconeis placentula,Diatoma vulgaris, andNitzschia dissipatawere dominant at site 1 (clean to nutrient-rich conditions).Fragilaria capucinavar.gracilisandGomphonema parvulumwere dominant at site 2 and their growth was accelerated by the moderately-nutrient-rich conditions.Luticola goepperitnana,N. palea, smallNitzschiaspp., and smallNaviculaspp. were dominant in the most polluted pools at site 3. We conclude that the LHR has a water quality gradient along its course, and that this causes marked changes in the epilithic diatom species compositions found along the river. The results confirm that epilithic diatoms are important bioindicators for assessing ecological quality in the LHR. [ABSTRACT FROM AUTHOR]

Epilithic diatoms were examined longitudinally with respect to trophic status and factor governing their distribution from a spring-fed lesser Himalayan stream; the Khanda Gad. The samples were collected at 4 stations from headwater to mouth; K1 to K4. The annual means of environmental variables - water temperature, channel width, depth, current velocity, discharge and dissolved oxygen increased from ?1 to K4 downstream. The taxa were grouped into exceptionally high (>50%), moderate (20-50%) and low (10-20%) abundance. The species, Achnanthidium minutissimum, Cymbella affinis, Cocconeis placentula var. euglypta and Gomphonema olivaceumwere abundant longitudinally. The longitudinal variation in the taxa abundance downstream were; decreasing abundance (Achnanthidium minutissimum, Planothidiumfrequentissimum, Platessa conspicua), increasing abundance {Cymbella affinis1 Cocconeis placentula var. euglypta, G. olivaceum) and other abundant taxa that appeared and disappeared. The trophic state was eutraphentic at ?1 and K4, while mesoeutraphentic at K2 and ??. The share of eutraphentic and mesoeutraphentic taxa varied little at ?1 but was considerably different at K4 compared to K2 and ?? where both forms accounted for 24-25% each. [ABSTRACT FROM AUTHOR]

Determining the ecological status of river ecosystems should be based on reference (near-natural) conditions and on the use of their biological communities. Identifying reference conditions is particularly difficult in largely disturbed watersheds, such as those of agricultural landscapes. Ecotype reference sites and their characteristic diatom communities were identified in the Guadiana watershed. Three different ecotypes were defined: rivers with siliceous bedrocks, upper watershed calcareous rivers, and mainland watercourses. Thirteen key stressors divided in four categories (channel alteration, hydrological pressure, pollution pressure, and river habitat pressure) were used to select reference sites in each ecotype. Multivariate techniques were used to describe type-specific reference diatom community in each ecotype. Because of the difficulty to define reference sites in the mainland watercourses, some sites were selected under the criterion of minimum impacted sites. Diatoms inhabiting sites included species tolerant to high nutrient concentration and mineralized waters, like Nitzschia inconspicua, Gomphonema parvulum, and Navicula veneta. These taxa defined the best condition (near-to-reference) in an ecotype highly impacted by human activities, the best possible in the long-lasting impaired conditions in the large river watercourses in agricultural landscapes. [ABSTRACT FROM AUTHOR]

Abstract: Diatoms are widely used for the bioassessment of permanent rivers and streams due to their broad distribution and their ability to integrate changes occurring in water composition and quality, but they have rarely been investigated in temporary streams. Water and epilithic diatom samples were collected from 60 sites in temporary streams distributed among the three largest Balearic Islands (Majorca, Minorca and Ibiza). The sampling design included only temporary streams that have water for at least 4–5 months during the annual period. The selected sites included minimally disturbed (reference sites) and other sites influenced by different degrees of human pressures. Each study site was sampled at least twice in different seasons to take into account the temporal variability in diatom assemblages (n =255). Non-metric multidimensional scaling (NMDS) and analyses of similarities (ANOSIM) were used to assess variation in the communities between a priori defined types and along to the degradation gradient, and to study the species tolerance to pollution. A diatom multimetric index (DIATMIB) was developed to assess the ecological status of temporary streams, as a combination of three metrics: abundance of sensitive taxa, abundance of tolerant taxa and a metric of chlorophyll a values. Individual diatom metrics and the multimetric DIATMIB were correlated in a significant way with phosphate, nitrate, ammonia, silicon dioxide, ash free dry mass and water electric conductivity. Cymbella vulgata, Diploneis oblongella and Encyonopsis microcephala appeared only in reference sites and in high and good status classes. These taxa were replaced by others such as Navicula veneta, Nitzschia inconspicua, N. frustulum and Planothidium frequentissimum that appeared in moderate, poor and bad status classes, which were characterized by high levels of organic/nutrient pollution. Our study validates the application of a diatom multimetric index as a good approach to classify the ecological status of temporary streams due to changes in the structure of diatom communities. We concluded that the multimetric index DIATMIB is a valuable tool for the assessment and future monitoring of temporary Mediterranean streams. [Copyright &y& Elsevier]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of the Institute of Science & Technology of Dumlupinar University / Dumlupinar Üniversitesi Fen Bilimleri Enstitüsü Dergisi is the property of Dumlupinar University, Institute of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Implementation of the European Union Water Framework Directive and associated national guidelines has emphasized the value of using biota, such as epilithic diatoms in streams, as indicators of water quality. However, guidelines for evaluating diatom samples have been established without explicitly evaluating their statistical robustness. We used epilithic diatom samples from 73 streams in northern Sweden and simulated the effects of variations in the counting sum size and taxonomic resolution of classifications for two indices indicating pollution (Indice de Polluo-sensibilité Spécifique, IPS) and acidity (acidity index for diatoms, ACID). Instead of the stipulated 400, we found that a count sum of 40 diatom valves for 50 streams, and 80 valves for 60 streams, would have been sufficient to obtain the same IPS index classification. The ACID index is more sensitive to count sum reductions, since the same classification would only have been obtained for 12 streams with 40 counted diatom valves or 24 streams with a count of 80 valves. Excluding rare taxa had negligible effects on the IPS and ACID indices. Excluding taxa occurring with less than 1.0% frequency affected the IPS classification of only one stream, and excluding taxa with less than 2.5% and 5.0% frequencies affected those of just one and no streams, respectively. The ACID index was affected for none, five, and 12 streams, respectively. At least in relatively unpolluted regions such as northern Sweden, our simulations suggest that a simplified methodological approach with site-specific counting sum sizes and reduced taxonomical resolution could be adopted, taking into account the way sites are classified in relation to established class boundaries. The simplified method is a step forward in improving the cost efficiency for stream monitoring, as costs of diatom analysis to obtain identical IPS and ACID classifications of our streams could be reduced considerably. Before the simplified method can be widely adopted, further simulations including regions with a higher proportion of polluted streams are required. [ABSTRACT FROM AUTHOR]

Abstract: Large-scale patterns of benthic diatom assemblages were analyzed in an agricultural basin, the Guadiana River. The distribution patterns of epilithic diatom assemblages were analyzed at different spatial scales: the whole watershed, the upper calcareous subcatchment and the mid-lower siliceous subcatchment. At the whole watershed scale, two major ecological gradients were revealed. The first one summarized the diatom distribution throughout a nutrient concentration gradient, while the second gradient was related to the geological structure of the watershed. Variance partitioning allowed the effects of the different sets of environmental parameters related to every CCA gradient to be separated. Analyzing the subcatchment gradients with partial CCA allowed us to define specific key factors that affect diatom species composition. Although water chemistry consistently played the most important role in structuring diatom assemblages in the Guadiana, spatial factors such as altitude or geographic location also explained some variation in diatom distribution. [Copyright &y& Elsevier]

Acid mine drainage (AMD) often exerts various environmental pressures on nearby water courses: chemical stress from low pH and dissolved metals; physical stress from metal oxide deposits. Affected streams can thus display a spatially variable combination of stress agents that may complicate its biomonitoring using native communities such as periphyton. Here, we have measured water and periphyton variables in four streams that surround an abandoned copper mine to determine which periphyton attributes consistently detected AMD impact in a complex environmental setting. Seventeen years after the end of commercial exploitation, the abandoned mine still decreases water quality in nearby streams: moderate acidification, very high metal load (Al, Ni, Cu, Zn), and a conspicuous presence of metal oxide deposits with diverse composition. Even under the resultant complex pattern of polluted conditions, periphyton was a reliable bioindicator of AMD. Epilithic diatom taxa tolerant of acidic conditions increased in AMD sites and, at severely impacted locations, species richness decreased. Also, algal biomass may have been negatively affected in some stream reaches affected by metal oxide deposits. Other periphyton attributes (total biomass, diatom diversity) seemed mostly unrelated to AMD. Diatom assemblage composition was the most sensitive and consistent bioindicator of mine drainage; besides, it rendered a biological assessment of AMD impact that largely coincided with the physicochemical evaluation. Still, including other taxonomic (proportion of acid-tolerant diatom species, diatom richness) and non-taxonomic (algal biomass) attributes in the biomonitoring procedure rendered a more comprehensive assessment of the negative consequences generated by AMD. [ABSTRACT FROM AUTHOR]

Use of diatoms in monitoring water quality is well acknowledged in developed countries, but only recently has the assessment started gaining importance in developing countries. Diatoms can be obtained from natural and artificial substrates. Appreciating the differences and similarities of diatom assemblages on both substrates may contribute to a better understanding and standardization particularly during monitoring of water quality. During this study we assessed diatom assemblages, biodiversity and trophic indices in relation to water quality along the Nairobi River. Fifteen sites were sampled in September 2000 during the dry season. Diatoms were collected from natural substrates (stones, pebbles) and artificial substrates (100% acrylic wool). On artificial and natural substrates, a total of 190 and 151 taxa were found, respectively, the majority of these taxa (80%) have cosmopolitan distribution and are also widespread throughout tropical African. Species composition changed downstream, five taxa dominated upper and mid stream sites whereas lower stream sites were dominated by one or two taxa. Species richness, diversity, dominance and evenness were positively correlated with NO3, O2 and altitude but decreased markedly downstream with a simultaneous increase in total dissolved solids, alkalinity, chemical oxygen demand and PO4. Ordination and classification (CANOCO and TWINSPAN) showed that diatom assemblages in the Nairobi River responded strongly to water quality changes with respect to concentrations of NO3, NO2, total dissolved solids and temperature. Taxa common at less impacted upstream sites included Gomphonema gracilis, Anomoeoneis brachysira and Fragilaria biceps; while common taxa at midstream sites with agricultural catchments were Gomphonema parvulum, Navicula cryptocephala, N. schroeteri, N. bryophila, N. halophila, Nitzschia linearis var. linearis and Cymbella silesica. Achnanthes minutissima var. saprophila, Gomphonema angustum, Navicula subminuscula, N. arvensis, Nitzschia palea and N. umbonata were most common at urban sites, which were polluted by residential and industrial effluents. Trophic diatom indices suggested that water quality was poor at most sites in the Nairobi River. Most sites along the river had low Generic Diatom Index values, GDI (<12) and high Trophic Diatom Index values, TDI 73-78 (median = 76) and 75-84 (median = 77) for artificial and natural substrates, respectively. This study showed that diatoms' response on natural and artificial substrates were similar and reflected environmental conditions correctly. [ABSTRACT FROM AUTHOR]

The potential use of epilithic diatoms as indicators of organic pollution was evaluated in Gravataí River, RS, (latitude 29°45′–30°12′ S; longitude 50°27′–51°12′ W). The river suffers agricultural impacts in its upper course and urban and industrial organic pollution in its lower course. Epilithic diatoms were sampled eight times from September 2000 to August 2002, at six sites. Species were identified and densities and relative abundances of populations were determined. Simultaneously, physical, chemical and microbiological variables were measured (water temperature, conductivity, turbidity, pH, dissolved oxygen, biochemical oxygen demand (BOD5), chemical oxygen demand, ammonium, organic nitrogen, total nitrogen, ortho-phosphate, total phosphate, chloride and faecal coliforms). In order to interpret the environmental and biological variables, discriminant analysis and the TWINSPAN methods (Two-Way Indicator Species Analysis) were applied. The results indicated that the concentrations of ortho-phosphate, ammonium, total organic nitrogen, BOD5 and faecal coliforms characterized a pollution gradient along the river, where changes in the abundance or species composition were observed. Species were classified into three groups: Group A, including species more tolerant to heavy organic pollution and eutrophication, represented by Luticola goeppertiana, L. mutica, Eolimna subminuscula, Nitzschia palea and Sellaphora pupula; Group B, comprised of tolerant and widely distributed species such as Eunotia bilunaris, Frustulia crassinervia, F. saxonica, Navicula cryptocephala, N. cryptotenella, Nitzschia palea var. tenuirostris, Surirella angusta, Pinnularia microstauron and Ulnaria ulna and Group C, with less pollution tolerant species represented by Eunotia sp. and Gomphonema parvulum. [ABSTRACT FROM AUTHOR]

Abstract: We report biological changes at several UK Acid Waters Monitoring Network lakes and streams that are spatially consistent with the recovery of water chemistry induced by reductions in acid deposition. These include trends toward more acid-sensitive epilithic diatom and macroinvertebrate assemblages, an increasing proportional abundance of macroinvertebrate predators, an increasing occurrence of acid-sensitive aquatic macrophyte species, and the recent appearance of juvenile (&#60;1 year old) brown trout in some of the more acidic flowing waters. Changes are often shown to be directly linked to annual variations in acidity. Although indicative of biological improvement in response to improving water chemistry, “recovery” in most cases is modest and very gradual. While specific ecological recovery endpoints are uncertain, it is likely that physical and biotic interactions are influencing the rate of recovery of certain groups of organisms at particular sites. [Copyright &y& Elsevier]

In order to study the anthropogenic impact of trace metals in the Caima and Mau River basins (north-central Portugal), 415 stream sediment samples were randomly collected in the main streams of these rivers and the minus 80-mesh fraction was analysed by Inductively Coupled Plasma – Optical Emission Spectrometry (ICP-OES). The presence of abandoned mines was identified as the main source of Cu, Pb, Cd and Ni in the area. A strong pair-wise correlation between Pb, Zn, Cd and Ni was found. In this study, the geochemical indices (Contamination Index (CI) and Multiple Pollution Index (MPI)), and the diatom indices (Specific Pollution Index (SPI) and Biological Diatom Index (BDI)) are used to define the Caima and Mau River basins environmental quality. The estimation of the CI and MPI indices shows that the sediments near Coval da Mó area are enriched with Pb, Cd, Zn Ni and Co suggesting an anthropogenic origin of metal contamination in this zone. In order to evaluate the biological effects caused by the trace metals, 17 sites were selected from the two River basins. Surface water and epilithic diatom communities were sampled during the summer of 2001. In general, the water and diatom data showed medium to good water quality. However, samples collected near the mining areas (Coval da Mó) revealed low abundance and diversity of diatom taxa indicating a stressed environment. Some diatoms showed morphologically abnormal valves that may be related to the high level of metal pollution in this area. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)