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Aim of the study: The Gala Lake, which has a status of National Park and is an under-protection area, is the one of the most important natural stagnant water bodies in the Marmara Region of Türkiye. However, it is under effect of a significant agricultural stress sourced by mainly paddy cultivation. In this research, the epiphytic diatoms of Gala Lake were investigated, and the trophic status of the lake was assessed by applying the Biological Diatom Index (BDI). Material and methods: Epiphytic diatom samples were collected from the submerged macrophytes from 5 selected locations on the lake (G1–G5) with different ecological characters observed to be exposed to different pollution pressures. Results and conclusions: As a result of taxonomic data, 37 diatom species were recorded by identifying a total of 2095 valves, and Cyclotella meneghiniana, Bacillaria paxillifera, and Navicula recens were found as the most dominant species for the Gala Lake. According to the results of bioindication data, Gala Lake was found to be in a "eutrophic state"—"having poor water quality" in terms of applied BDI.

The Ergene River is the most significant fluvial ecosystem located in the Thrace Region of Turkey. But it is being exposed to an intensive organic – inorganic pollution by means of agricultural – industrial applications conducted around its basin. In this research, the epipelic (EPP) diatoms of the Ergene River were investigated and the water quality was evaluated using the determined physical, chemical and biological data. EPP diatom samples were collected from upstream, middlestream and downstream of the Ergene River and certain physicochemical parameters (dissolved oxygen, oxygen saturation, pH, electrical conductivity, total dissolved solids, salinity, turbidity, nitrate, nitrite, ammonium, phosphate, sulphate, fluoride, chemical oxygen demand, biological oxygen demand and oxidation-reduction potential) were measured during the field – laboratory studies. Also, the Biological Diatom Index (BDI) was used to determine the trophic status of the Ergene River in terms of EPP diatoms. According to the results of the physicochemical analysis, upstream of the Ergene River has Class I – II water quality and middle – downstream of the Ergene River have Class III – IV water quality in general. According to the results of the biological analysis, 24 diatom species were recorded in the upstream samples, 4 diatom species were recorded in the middlestream samples. and 7 diatom species were recorded in the downstream samples. Cymbopleura amphicephala (Nägeli) Krammer, Nitzschia umbonata (Ehrenberg) Lange-Bertalot and Nitzschia capitellata Hustedt were determined as the most dominant species in the up – middle – downstream of Ergene River respectively. According to the result of the BDI, the upstream of Ergene River was found to be in an oligotrophic state – has high water quality and the middle – downstream of Ergene River were found to be in a eutrophic state – have poor water quality.

Bioassessment is widely used to measure ecological integrity of natural habitats following anthropogenic disturbances and modifications. Traditionally, bioassessment has been based exclusively on species-environment interactions, i.e. niche processes. However, dispersal processes, and in particular mass effect, could mask the influence of niche processes and lead to erroneous conclusions about ecosystem health. To circumvent this problem, we identified 40 diatom species with distributions driven primarily by mass effect and propose an alternative version of the Biological Diatom Index (IBD2007) excluding these species. We tested the environmental responses of both the original IBD (IBD2007) and the modified IBD (IBDmod) with a benthic diatom dataset from France, collected between 2007 and 2013 and including 9487 samples from 3913 spatially distinct localities. Our results indicate a better relationship between the IBDmod scores and environmental conditions, compared to the IBD2007 scores, leading to a more accurate determination of river ecological status, especially in conditions of moderate nutrient enrichment. This study supports the idea that mass effect may result in biased evaluation of water quality. It is advocated that this process is considered in other diatom-based indices, and by extension, in any biotic index.

The Meriç River is one of the longest rivers of the Balkans and the Tunca River is the most significant tributary of the Meriç River. In the present study, the epipelic diatoms of the Meriç and Tunca Rivers were investigated and the water quality was evaluated from a physicochemical and biological perspective. Epipelic (EPP) diatoms were collected from the middlestream of the Meriç River (Edirne Province of Turkey) and from the downstream of the Tunca River (before emptying into the Meriç River) and certain physicochemical parameters including dissolved oxygen (DO), oxygen saturation (OS), pH, electrical conductivity (EC), total dissolved solids (TDS), salinity, turbidity, nitrate (NO3), nitrite (NO2), ammonium (NH4), phosphate (PO4), sulphate (SO4), chemical oxygen demand (COD) and oxidation-reduction potential (ORP) were measured during the field studies. The Biological Diatom Index (IBD) was used to determine the trophic status of the Meriç and Tunca Rivers in terms of EPP diatoms, and Cluster Analysis (CA) was applied to the detected biological data in order to classify the identified diatom taxa in terms of their dominance in the system. According to the results of the physicochemical analysis, the Meriç and Tunca Rivers have I. – II. Class water quality in terms of dissolved oxygen, oxygen saturation, pH, EC, TDS, NO3, NH4, SO4 and COD parameters; and have III. – IV. Class water quality in terms of NO2 and PO4 parameters. 24 diatom species were recorded in the Meriç River by counting a total of 403 valves and a total of 19 diatom species were identified by counting a total of 409 diatom valves in the Tunca River. Cyclotella atomus Hustedt, Navicula gregaria Donkin, Nitzschia palea (Kützing) W.Smith and Nitzschia subacicularis Hustedt, were determined as the most dominant species in the Meriç River and Navicula erifuga Lange-Bertalot, Navicula gregaria Donkin and Navicula rostellata Kützing were recorded as the most dominant taxa in the Tunca River. According to the result of the IBD, the investigated rivers were found to be in a meso-eutrophic state and according to the results of CA, three statistical clusters were formed for both rivers, and were named as “dominant taxa”, “frequent taxa” and “rare taxa”.

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

Historical diatom records provide a means of retrospectively determining water quality and inferring ecological condition in rivers and streams. In this study we re-sampled sites originally sampled 48 years previously. We then determined the scores for the Biological Diatom Index (BDI) and the South African Diatom Index (SADI) for each dataset. The results revealed that the present day conditions in this relatively undisturbed locality were almost identical to those reflected by the samples collected half a century before. This illustrates the value of historical diatom data for the purposes of determining antecedent water quality. [ABSTRACT FROM AUTHOR]

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.)

Copyright of Contributii Botanice is the property of Contributii Botanice 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.)

Abstract: Vineyard areas are important causes of water contamination, especially by pesticides and residues. These compounds can markedly disturb aquatic communities particularly photosynthetic organisms that are targeted by herbicides. Biofilms and diatoms were used as bioindicators for quality assessment in the Morcille watershed, an area impacted by Beaujolais vineyards (SE France), during the pesticide spreading period (April–May 2008). Biofilms were allowed to settle on glass slides for 4 or 8 weeks at three sites along a 7-km long gradient of trophic (mainly orthophosphate) and pesticide pollution. After a 4-week colonization, samples from the two contaminated downstream sites were transferred upstream to the clean site for 4 weeks while others were left in the same place. In vivo fluorescence measurements indicated that the periphytic communities were dominated by diatoms. Going downstream, biofilm biomass and diatom species richness decreased; normalized diatom indices (including the French standard BDI) expressed the increase in trophic status quite well. The species composition of the assemblages was used to discriminate between the effects of nutrients and toxicants, which increased simultaneously as the river continued downstream. The way in which the biofilm samples transferred upstream recovered was quite different depending on the location of the original site in the contamination gradient. Most of the quantitative descriptors reached a level comparable to that of the reference communities, but the diatom assemblages (cell density per surface unit, taxonomic composition) varied between dates and along the gradient. These communities did not entirely recover a reference structure but the increase in diversity, associated with the settlement of sensitive species, suggested an elevated recovery potential. [Copyright &y& Elsevier]

Abstract: The Biological Diatom Index (BDI) is a standardized method routinely used in France for the surveillance of watercourse quality. This index is based on a list of 209 key species showing different pollution sensitivities. The pollution sensitivity, or “ecological profile”, is determined through the species presence probability values along a seven quality classes gradient. In a sample, the presence and abundance of species from this list are used to calculate the BDI score. Recently, water managers pointed out several weaknesses of this index: (a) the BDI fails to correctly assess water quality in acidobiontic and brackish conditions, and (b) pollution sensitivity and tolerance of several key species used to calculate the index need to be improved. This paper presents and discusses the new version of the BDI, called BDI-2006. 2802 samples were used to create this new index (samples collected on all French river types during the last thirty years), where 1063 diatom species were identified. For each sample, the community was described with species relative abundance, and relevant physico-chemical parameters were collected: pH, conductivity, dissolved oxygen, biological oxygen demand, ammonium, orthophosphates and nitrates. Eight hundreds and thirty eight key species were finally kept, including species typical of acidic and brackish waters, tropical taxa and abnormal forms of many widespread taxa (as evidence of toxicological impacts). The physico-chemical and the biological datasets were explored with classical analysis (Principal Component Analysis) and neural networks (Self-Organizing Maps), combined to draw the new key species ecological profiles. Comparing to the initial version of the BDI, several species profiles (Nitzschia paleacea for example) were clearly enhanced. This new version was adopted by the French standardisation authority (AFNOR) in October 2007. [Copyright &y& Elsevier]

• Bioassessment of ecological status is based on species-environment relationships. • Mass effect influences communities' structure and blurs these relationships. • A new Diatom Index (IBD mod) was created without species influenced by mass effect. • IBD mod better captures local environmental conditions compared to the original index. • Taking mass effect into account allows more accurate bioassessments of water quality. Bioassessment is widely used to measure ecological integrity of natural habitats following anthropogenic disturbances and modifications. Traditionally, bioassessment has been based exclusively on species-environment interactions, i.e. niche processes. However, dispersal processes, and in particular mass effect, could mask the influence of niche processes and lead to erroneous conclusions about ecosystem health. To circumvent this problem, we identified 40 diatom species with distributions driven primarily by mass effect and propose an alternative version of the Biological Diatom Index (IBD 2007) excluding these species. We tested the environmental responses of both the original IBD (IBD 2007) and the modified IBD (IBD mod) with a benthic diatom dataset from France, collected between 2007 and 2013 and including 9487 samples from 3913 spatially distinct localities. Our results indicate a better relationship between the IBD mod scores and environmental conditions, compared to the IBD 2007 scores, leading to a more accurate determination of river ecological status, especially in conditions of moderate nutrient enrichment. This study supports the idea that mass effect may result in biased evaluation of water quality. It is advocated that this process is considered in other diatom-based indices, and by extension, in any biotic index. [ABSTRACT FROM AUTHOR]