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1.
The European Water Framework Directive (EU WFD) aims to improve and maintain the water quality of lakes and rivers. Diatoms play an important role for implementing the EU WFD as they are widely used to assess water quality. To asses and use diatom-based evaluations in practice, it is essential to know and to minimize the analyst-dependent variability of the primary diatom results. We compare the counting results of benthic diatoms from two river and two lake samples as identified by 40 participants of the first German benthic diatom intercalibration exercise. Differences among participants and auditors are calculated with the Bray-Curtis distance, and similarities are graphically displayed by detrended correspondence analyses. Additionally, this study identifies the effects of counting variances on the ecological water assessment with the German PHYLIB method for implementing the EU WFD using the above dataset. Counting result differences among participants may have a significant impact on the assessed water quality. Some taxonomically problematic taxa do not have indicator values (no impact), sometimes, several taxonomic mistakes counterbalance each other during assessment (no or minor impact), and sometimes, taxonomic differences greatly influence the assessment due to highly deviating taxon abundances and/or strongly differing indicator values between mistaken taxa. Intercalibration exercises promote discussion about taxonomy, identify problematic taxa, and harmonize taxonomic concepts among diatomists. Thus, the shown analyst-induced variability of diatom counts may be reduced with an intercalibration exercise, thereby further refining the accuracy of water quality assessments. 相似文献
2.
Soda pans are protected in the European Union as Natura 2000 areas in the category of “Pannonic saline steppes and marshes”. There are at least six soda pans of reference status in Serbia and only a half have strict legal protection. The number of similar, but disturbed (modified) habitats that could be reconstructed is still unknown. We conducted sampling in five natural and two disturbed soda pans aiming to compare a difference in physical and chemical water properties and benthic diatom communities. In addition, we tried to apply recently developed Diatom Index for Soda Pans (DISP) and Trait-based index (TBI) to test the applicability of taxonomic and trait-based approaches in ecological status assessment of soda pans in the southern part of the Carpathian Basin. In contrast to natural soda pans, lower pH and nutrients levels were recorded in disturbed pans. A total of 86 taxa of benthic diatoms, including 11 new for diatom flora of Serbia, were identified. A lower species richness and Shannon index was recorded in natural soda pans. Nitzschia austriaca, N. supralitorea, Navicula veneta and N. wiesneri were dominant diatoms in soda pans of the reference status. Both diatom indices were in average lower in disturbed pans, and this difference was statistically significant for DISP index. We concluded that two indices, supplemented with indicator values for some local diatom species, can be a promising tool for soda pan conservation in this part of the Carpathian Basin. 相似文献
3.
Diatoms are frequently used as indicators of eutrophication in temperate systems, but little is known about their application
to impacted African tropical systems. Five streams located within Gombe Stream National Park and five streams supporting human
settlements draining into Lake Tanganyika, East Africa, were investigated for species composition, richness and diversity
of epilithic algae. In addition, a trophic diatom index (TDI) developed for monitoring European rivers was applied to these
tropical systems. 54 specific and infraspecific diatom taxa representing 20 genera were identified for all sites with Achnanthes s.l., Gomphonema and Navicula s.l. being the most common genera. Species richness varied between 10 and 21 in disturbed streams and 13 and 19 in undisturbed
streams. Nutrients were significantly enriched in streams draining the deforested watersheds but indices of diversity and
evenness (Shannon H, J and Simpson–Yule D, E) did not show any significant differences between streams in forested and deforested
watersheds. Significant differences were observed between pooled data for the TDI between forested and deforested watersheds.
Analysis of percent pollution tolerant diatom taxa indicates that organic pollution of streams in deforested watersheds may
be contributing to eutrophication. This study shows that African diatoms, cosmopolitan or resembling well-known North American
and European taxa, allows for trophic indices tailored to the autecological preferences of species to be applied to new regions,
although intensive studies on these African taxa will lead to more accurate results. Measures of species-richness and diversity,
historically used to describe the state of an ecosystem, may not be suitable to evaluate streams which are not grossly polluted.
Electronic supplementary material Electronic supplementary material is available for this article at
and accessible for authorised users. 相似文献
4.
Diatom concentrations in surface sediments are positively correlated with limnetic chlorophyll a concentrations in Florida (USA) lakes. Using this relationship, I examine models that provide quantitative inferences for trophic state in historical applications.The best model predicts chlorophyll a trophic state index (TSI) values from log-transformed diatom concentrations and explains approximately half the variance in the dependent variable. Diatom accumulation rates are not better than sedimentary diatom concentrations as predictors of TSI. The entire diatom assemblage is as sensitive an indicator of TSI as are the planktonic diatoms alone. A model that considers the ecological preferences of specific taxa was found to be a better predictor than the model based on total diatom concentration.The sedimentary diatom concentration model provides a useful method for assessing historical changes in primary productivity, except in lakes where factors (e.g., silica limitation, blue-green bacterial inhibition) limited diatom production, or post-depositional changes removed sedimentary diatoms. TSI inferences are presented for sediment cores from two Florida lakes, one of which demonstrates a problematic application, and the other of which does not. 相似文献
5.
Despite the widespread application of periphytic diatoms to water quality assessment at a regional level, there is no standard
European sampling protocol or associated assessment metrics. Furthermore, relatively little is known about the uncertainty
in the results of such assessments. One of the objectives of the European project for the Standardisation of River Classifications
(STAR) is to improve and standardise diatom assessment methods. An extensive diatom ring test, together with an audit of the
project results, provided a better understanding and quantification of the uncertainty in quality assessment of running waters
using diatoms. The variation in multimetric analysis shows that the choice of site and substrate for sampling, the inter-operator
differences in diatom taxonomy and the counting techniques are the primary sources of uncertainty. To some extent, this variation
also reveals the robustness of specific metrics in relation to the sources of uncertainty. Of the three most common substrate
types tested (stone, macrophyte and sediment), macrophytes emerge as the most preferred substrate for diatom sampling when
performing multimetric water quality assessment. 相似文献
6.
The European list of aquatic macro-invertebrate taxa, and its associated ecological database, originated within the context
of the AQEM project and have been extended during the STAR project. The AQEM/STAR taxalist is a product of co-operation between
applied freshwater ecologists and scientists from different zoological fields, applied partners and the administration. The
basic idea is that a sound understanding of benthic invertebrate ecology is a prerequisite for the implementation of a biological
approach to aquatic ecosystem management in Europe. The database has been generated under the management of BOKU (University
of Natural Resources and Applied Life Sciences, Vienna) and UDE (University of Duisburg-Essen) and provides an important means
of standardisation and unification of ecological classifications in Europe. This paper outlines the aims for setting up the
AQEM/STAR macro-invertebrate taxalist and autecological database and provides a current summary of the numbers of aquatic
orders, families, species, and species occurrences in 14 European countries. The number of available and applicable assignments
of taxa to each ecological parameter is summarised and examples are given for different parameters and taxonomic groups. Gaps
in the autecological information are identified and discussed. Besides its ecological relevance, the operational character
of this database is underlined by the fact that it provides the associated taxon codes for each of five different European
assessment systems for nearly 10,000 European macro-invertebrate taxa. 相似文献
7.
The interactions between sensitivity and variability of macrophyte and diatom communities were evaluated as a research support
of methodologies required by the Water Framework Directive. Slope and shading were identified as additional typological parameters
improving links between unimpacted macrophyte communities and running water types. Two other studies demonstrated indication
value of macrophytes for assessment of nutrient enrichment and hydromorphological degradation. The special exercises were
realized within the STAR project to evaluate sources of variability/uncertainty in assessment methods based on macrophytes
and diatoms. Sampling period and shading of the site were found as major factors affecting variability in macrophyte assessment
results. Uncertainty of diatom assessment is predominantly associated with selection of site, substrate type and taxonomic
identification. Further extension of indication systems and definition of macrophyte/diatom-specific typology of running waters
are considered as the main aims of subsequent investigations. 相似文献
8.
Relationships between taxonomic composition of shallow epilithic algal communities and nine environmental variables in 32 lakes of different trophic states in Ireland were explored using gradient analysis. A canonical correspondence analysis using four representative environmental variables, alkalinity (correlated with pH and conductivity), maximum phytoplankton chl a (CHL max) (correlated with total P, total N, and chl), turbidity, and water color explained 21% of the variance in taxa distributions. The first two axes were significant and accounted for 77% of the variance in the periphyton–environmental relationship. The first axis was strongly related to alkalinity and color, which reflected geology and land use in the watersheds. The second axis was most correlated with CHL max, and separation of lakes corresponded to their Organization for Economic Cooperation and Development (OECD) trophic classification based on water chemistry. Eutrophic lakes were characterized by cyanobacteria taxa and Stigeoclonium sp. Diatoms and desmids were generally more abundant in oligotrophic and mesotrophic lakes. Values for diatom trophic indices were poor indicators of trophic state. Weighted averaging regression and calibration techniques were used to develop transfer functions between 84 taxa and total P, total N, and CHL max. The total P inference model predicted OECD trophic classification correctly for 84% of the lakes. Values for taxa preferences resulting from such models can provide the foundation for biomonitoring schemes using extant periphyton communities. The turnover time of periphyton taxa should integrate changes in environmental conditions at a temporal scale intermediate to surface‐sediment fossil diatom assemblages and water column variables, which may be more appropriate for detecting annual changes. 相似文献
9.
The “All Taxa Biodiversity Inventories” (ATBIs) project coordinated by the European Distributed Institute of Taxonomy (EDIT) aims to achieve a baseline biodiversity assessment of flora and fauna in those regions characterized by a lack of knowledge and a high potential for biodiversity. Within the framework of the ATBIs, the aim of this study was to analyse the diatom flora and ecology of a complex of freshwater ecosystems in the Maritime Alps Natural Park (Italy), designated as a Special area of Conservation under the European Habitat Directive. We sampled epilithic and epiphytic diatoms in different habitats in 24 sites: shallow lake, springs, and streams. Our analysis resulted in a list of 138 diatom taxa, highlighting the great biodiversity and the complex structure of the investigated diatom communities. The taxa list included a wide range of uncommon species, including some recorded for the first time in North-Western Italy. Among the different habitats the highest level of diversity was found in the more lentic waters, in particular in limnocrene springs. These results show that the diatom communities of pristine and undisturbed high-mountain environments are rich and complex, despite the severe environmental conditions. 相似文献
10.
The surface sediment diatom analysis of 28 Algoma lakes (pH 4.40–8.13) indicates that even though each lake has a widely different aquatic environment and characteristic diatom assemblage, a definite relationship exists between the lake water pH and their diatom assemblages. In the acidic lakes acidobiontic and acidophilous diatom species predominate whereas in circumneutral and alkaline lakes circumneutral and alkaliphilous diatoms were most common. Cluster analysis of the pH indicator diatom assemblages grouped the study lakes into three distinct cluster groups. These groups also closely corresponded to lake water pH. On the basis of published ecological information as well as their presence in our study lakes, the pH indicator status of a number of diatom taxa have been discussed. A detailed listing of the diatom taxa identified and their pH indicator status is provided in order to facilitate their use in future diatom-inferred pH studies. 相似文献
11.
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, NO 3-N, electrical conductivity, NH4-N and CaCO 3. 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. 相似文献
12.
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. 相似文献
13.
A index for monitoring the trophic status of rivers based on diatom composition (‚trophic diatom index’, TDI) has been developed,
in response to the National Rivers Authority (England & Wales)'s needs under the terms of the Urban Wastewater Treatment Directive
of the European Community. The index is based on a suite of 86 taxa selected both for their indicator value and ease of identification.
When tested on a dataset from 70 sites free of significant organic pollution, this index was more highly correlated with aqueous
P concentrations than previous diatom indices. However, where there was heavy organic pollution, it was difficult to separate
the effects of eutrophication from other effects. For this reason, the value of TDI is supplemented by an indication of the
proportion of the sample that is composed of taxa tolerant to organic pollution.
The index was tested on the R. Browney, N-E. England, above and below a major sewage discharge. TDI values indicated that
the effect of inorganic nutrients on the river downstream of the discharge was slight as the river was already nutrient-rich,
but there was a large increase in the proportion of organic pollution-tolerant taxa. This indicates that the river was already
so eutrophic upstream of the discharge that tertiary treatment to remove P would not be effective unless other aspects of
the discharge were also improved. 相似文献
14.
Biological and chemical data were processed to estimate trophic stage and degree of pollution in several streams and rivers
in southern Poland. The majority were eutrophic and some of them heavily polluted; only a few were oligo-mesotrophic. The
differences in the water quality of the rivers were reflected by different types of diatom community and also by the values
for some diatom indices, which were calculated using the latest version of the 'Omnidia' database software. Except for the
Sládeček's index, all diatom indices correlated significantly with organic load (COD), oxygen concentration, conductivity
and most of the measured ions. Some indices showed a significant negative correlation with trophic level (expressed by NH 4-N and PO 4-P). In general, IPS (Specific Pollution Sensitivity Index) and GDI (Generic Diatom Index) indices gave the best results.
Among the investigated diatom communities, only a few taxa indicated oligo-mesotrophy and oligo-β-mesosaprobity. Most of the
sites were characterised by a greater relative contribution of eutraphent and tolerant ones as well as α-mesosaprobic and
polysaprobic diatoms. This study suggests that the structure of benthic diatom communities and diatom indices, especially
GDI, can be applied for monitoring rivers in Poland.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
15.
The European Union’s Water Framework Directive has set a target of achieving good ecological status for all aquatic environments
in Europe by 2015. In order to determine the quality of aquatic environments, biological indicators such as diatoms are often
used. However, biotic diatom indices can be difficult and time consuming to use because of complexity of species determination.
We investigated whether the biological traits of diatoms in rivers (life-forms, size classes and ecological guilds) could
be used to assess organic pollution and trophic level. We worked on a data set comprising 315 diatom species, determined at
328 river stations of south-east France and a variety of parameters. The abundances of some biological traits differed significantly
between the different organic pollution and trophic levels, particularly stalked diatoms, and the motile and low-profile guilds. 相似文献
17.
Diatoms are excellent ecological indicators of water quality because they are broadly distributed, they show high species diversity and they respond rapidly to human pressures. In Europe, the Water Framework Directive (WFD) gives the legal basis for the use of this indicator for water quality assessment and its management. Several quality indices, like the Specific Polluosensitivity Index (SPI), were developed to assess the ecological quality status of rivers based on diatom communities. It is based on morphological identifications and count of diatom species present in natural biofilms using a microscope. This methodology requires high taxonomic skills and several hours of analysis per sample as 400 individuals must be identified to species level. Since several years, a molecular approach based on DNA metabarcoding combined to High-Throughput Sequencing (HTS) is developed to characterize species assemblages in environmental samples which is potentially faster and cheaper. The ability of this approach to provide reliable diatom inventories has been demonstrated and its application to water quality assessment is currently being improved. Despite optimization of the DNA metabarcoding process with diatoms, few studies had yet extended it at the scale of a freshwater monitoring network and evaluated the reliability of its quality assessment compared to the classical morphological approach.In the present study we applied DNA metabarcoding to the river monitoring network of the tropical Island Mayotte. This island is a French département since 2011 and the WFD has to be applied. This offered the opportunity to scale up the comparison of molecular and morphological approaches and their ability to produce comparable community inventories and water quality assessments. Benthic diatoms were sampled following WFD standards in 45 river sites in 2014 and 2015 (80 samples). All samples were submitted in parallel to the molecular and the morphological approaches. DNA metabarcoding was carried out using Genelute DNA extraction method, rbcL DNA barcode and PGM sequencing, while microscopic counts were carried out for the classical methodology. Diatom community structures in terms of molecular (OTUs) and of morphological (species) were significantly correlated. However, only 13% of the species was shared by both approaches, with qualitative and quantitative variation due to i) the incompleteness of the reference library (82% of morphological species are not represented in the database), ii) limits in taxonomic knowledge and iii) biases in the estimation of relative abundances linked to diatom cell biovolume. However, ecological quality status assessed with the molecular and morphological SPI values were congruent, and little affected by sequencing depth. DNA metabarcoding of diatom communities allowed a reliable estimation of the quality status for most of the rivers at the scale of the full biomonitoring network of Mayotte Island. 相似文献
18.
Mediterranean coastal areas are characterised by heavily transformed landscapes and an ever-increasing number of ponds are
subjected to strong alterations. Although benthic diatoms and macroinvertebrates are widely used as indicators in freshwater
ecosystems, little is still known about the diatom communities of lowland freshwater ponds in the Mediterranean region, and,
furthermore, there are few macroinvertebrate-based methods to assess their ecological quality, especially in Italy. This article
undertakes an analysis of benthic diatom and macroinvertebrate communities of permanent freshwater ponds, selected along a
gradient of anthropogenic pressures, to identify community indicators (taxa and/or metrics) useful to evaluate the effect
of human impacts. A series of 21 ponds were sampled along Tyrrhenian coast in central Italy. Five of these ponds, in a good
conservations status and surrounded by woodland were selected as ‘reference sites’ for macroinvertebrates and epipelic diatoms.
The remaining sixteen ponds were located in an agricultural landscape subject to different levels of human impact. The total
number of macroinvertebrate taxa found in each pond was significantly higher in reference sites than in both the intermediate
and heavily degraded ones, whereas the diatom species richness did not result in a good community variable to evaluate the
pond ecological quality. The analysis revealed a substantial difference among the compositions of diatom communities between
reference ponds and degraded ponds. The former were characterised by the presence of several species belonging to genera,
such as Pinnularia sp., Eunotia sp., Stauroneis sp., Neidium sp., all of which were mostly absent from degraded ponds. Furthermore, the taxonomic richnesses of some macroinvetebrate
groups (Odonata, Ephemeroptera, Trichoptera, Coleoptera), and taxa composition attributes of macroinvertebrate communities
(total abundance, percentages of top three dominant taxa, percentages of Pleidae, Ancylidae, Hirudinea, Hydracarina) significantly
correlated with variables linked with anthropogenic pressures. The results of the investigation suggested that diatoms tended
more to reflect water chemistry through changes in community structure, whereas invertebrates responded to physical habitat
changes primarily through changes in taxonomic richness. The methodologies developed for the analysis of freshwater benthic
diatom and macroinvertebrate communities may have a considerable potential as a tool for assessing the ecological status of
this type of water body, complying with the European Union Water Framework Directive 2000/60/EC.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Guest editors: B. Oertli, R. Cereghino, A. Hull & R. Miracle
Pond Conservation: From Science to Practice. 3rd Conference of the European Pond Conservation Network, Valencia, Spain, 14–16
May 2008 相似文献
19.
Coherence between ecological status assessment by phytoplankton and attached diatoms was analyzed in the littoral zone of Lake Balaton. Sampling of periphytic diatoms, phytoplankton, and water were carried out at ten different littoral sites in the northern and southern shores of the lake for a year. Phytoplankton species were sorted into functional groups and ecological status was assessed by means of the phytoplankton assemblage Q index. The index TDIL was calculated using quantitative attached diatom data. Significant differences were found between the ecological assessments based on phytoplankton and phytobenthos metrics, both seasonally and spatially. The Q index indicated ecological states varying from bad to good, while the average of diatom indices varied from moderate to high conditions. The Q index provided more realistic ecological status of Lake Balaton, compared with trophic status based on TP values, especially in the summer period. Differences in the response-time indication of phytoplankton and attached diatoms suggest that lack of coherence should also be expected between the responses of other BQEs. 相似文献
20.
The relationship between surface sediment diatoms and summer water quality was investigated at 49 lakes in the middle and lower reaches of the Yangtze River. Lakes ranging from oligomesotrophic to hypereutrophic were examined, providing an obvious nutrient gradient. With the shift from mesotrophic to eutrophic levels, diatom multi-ecotypes dominated by epiphytic and facultative planktonic taxa were replaced by nutrient-tolerant planktonic taxa, such as Cyclotella meneghiniana Skvortzow, C. atomus Hustedt,Cyclostephanos Round, and Stephanodiscus Ehrenberg etc., reflecting the nutrient changes in the lake.The relationship between diatoms and summer water quality indices was explored further using numeric analysis. Canonical correspondence analysis (CCA) with forward selection and a Monte Carlo permutation test revealed that of all 25 summer water environmental variables, total phosphorus (TP), chlorophyll a (Chzl a), Secchi depth (SD), dissolved inorganic phosphorus, C1-, SO42-, Mg2 , CO32-, and water depth were significant variables (P<0.05) in explaining diatom distributions. Of these, TP, Chl a, SD, and C1-, were the most important variables. The result of the correlation analysis also showed that a significant correlation exists among these variables, implying that these indices are either interconnected or independent in explaining the diatom data. For phosphorus-limited sites, TP was the most significant variable affecting the diatoms, also affecting changes in Chl a, SD, and iron concentrations. The independence of Chl a may be related to algal competition induced by lake eutrophication, resulting in the feedback to diatom community.In addition to TP, SD can be related to sediment disturbance by wave action and the growth of macrophytes in large shallow lakes. These relationships between diatom ecotypes and water quality provide the basis for a future quantitative reconstruction of historic lake nutrient evolution in the study area and will also provide a wealth of modern ecological knowledge that can be used to interpret fossil diatom records. 相似文献
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