The Kızılırmak River is the longest river (1.355 km) in Turkey and flows into the Black Sea. Main pressures in the basin are waste water discharges, widespread agriculture, livestock activities, and ...excessive salinity due to the natural formation. In this study, the performance of the most widely used European diatom indices (IPS, IDG, IBD, EPI-D, TDI, and TI) was tested statistically by comparing them with the indicators of organic pollution (biological oxygen demand and ammonium-nitrogen), eutrophication (orthophosphate and nitrate-nitrogen) and salinization (electrical conductivity) in the Kızılırmak basin, Turkey. For this purpose, a total of 97 diatom samples from 33 rivers were collected seasonally in 2014 and 215 species were identified. Principal component analysis was performed to evaluate the “general degradation” in the basin, and linear regression was used to calculate the correlations with diatom indices. As a result, EPI-D, IPS, IBD, and TI were strongly correlated indices, respectively, while IDG and TDI had the lowest correlations with general degradation. Only the EPI-D index was significantly correlated with all environmental variables. Our results showed that the EPI-D index can be used for the ecological status assessment in terms of phytobenthos in the Kızılırmak basin in line with the Water Framework Directive.
Biomonitoring of least disturbed areas is a crucial issue to accurately assess the ecological status of surface waters and ensure their sustainability. Diatom metrics are important tools for the ...assessment of environmental conditions of lotic ecosystems to achieve environmental sustainability. The present study was aimed to evaluate the ecological status of least disturbed areas in the Antalya River basin (Turkey) using diatom indices developed from different ecoregion. Diatom species such as
Cymbella excisa
,
Achnanthidium minutissimum
,
Cocconeis euglypta
, and
Cocconeis placentula
were the most contributing species to the dissimilarity of sampling stations between rainy and dry seasons. The first two axes of canonical correspondence analysis (CCA) elucidated a strong (86%) correlation between diatom taxa and stressors. Results of the Monte Carlo permutation test indicated that total phosphorus (TP), water temperature, Tin (Sn), total organic carbon, zinc, and pH are significantly influential ecological factors on the distribution of diatom taxa among sampling stations. The Spearman correlation rank test indicated that diatom indices had significant positive and negative correlations with TP gradient. Results revealed that diatom indices developed from different ecoregions have different scores for the eco-assessment of similar sampling stations. European diatom indices mostly showed similar behavior in the bioassessment of the ecological status of rivers in the Antalya region compared to the different ecoregion. Among European diatom indices, TIT was more competitive and could give better results in the bio-evaluation of rivers in the Antalya River basin. Using diatom indices developed from different ecoregions may lead to an erroneous assessment of water quality. Accordingly, ecoregional specific diatom metrics are needed to accurately determine the surface water quality.
Graphical abstract
Eco-assessment of least disturbed areas of the Antalya River basin: application of diatom indices from different ecoregions: Abuzer Çelekli, Ömer Lekesiz, Tolga Çetin
Ecological Indicators. First assessment of lakes’ water quality in Aras River catchment (Turkey); application of phytoplankton metrics and multivariate approach. Abuzer Çelekli, Seda Kayhan, Tolga ...Çetin.
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•The first attempt to assess water quality of five lakes in the Aras River basin.•Multivariate approaches demonstrated the phytoplankton-stressors interactions.•Nutrients, temperature, and altitude showed significant effects on phytoplankton distribution.•Responses of phytoplankton taxa to stressors provide crucial ecological information.•Ecological status of lakes could be assessed by using the PTI and Med-PTI.
This study is the first attempt to determine responses of phytoplankton assemblages to stressors using multivariate approaches and to evaluate the limno-ecological status of Aktaş, Çıldır, Aygır, Deniz and Balık lakes in the Aras River system (Turkey) using phytoplankton metrics according to the requirements of Water Framework Directive. Samples were collected in August and October of 2014, and June of 2015 by using the standard protocols. The first two axes of canonical correspondence analysis (CCA) elucidated strong correlations (λ1 = 0.937, 99.7% and λ2 = 0.763, 98.5%) between phytoplankton species and stressors with a 27.2% of the cumulative variance of species data. The Monte Carlo permutation test with the forward selection exhibited the significant effects of dissolved oxygen, orthophosphate (P-PO4), total phosphorus (TP), biological oxygen demand (BOD5), water temperature, nitrite (N-NO2), and altitude on the phytoplankton distribution among lakes. Lake Aktaş was closely related to N-NO2, TP, P-PO4, and BOD5 and characterized by species Messastrum gracile, Oocystis borgei, Treubaria triappendiculata, Snowella lacustris, Tetraëdron minimum, and Lemmermannia komarekii. They preferred N-NO2 higher than 90th percentile (0.026 mg/L) and TP higher than the 75th percentile (0.270 mg/L). Phytoplankton trophic index (PTI) scores varied from 2.06 in Lake Aygır to 2.36 in Lake Aktaş, while a range between 0.89 in Lake Aktaş and 1.81 in Lake Aygır was calculated according to Mediterranean phytoplankton index (Med-PTI). The correlations of PTI and Med-PTI (R2 = 0.94 and 0.90, respectively) with logTP gradient indicated congruent results. A high ecological status was found in Lake Çıldır, when Aygır, Deniz, and Balık lakes had good environmental conditions. Lake Aktaş showed a moderate ecological condition. The present study confirmed that phytoplankton assemblages closely integrated with the limno-ecological status of lakes in the Aras catchment, which could be assessed by using the PTI and Med-PTI.
Ecological assessment of freshwater ecosystems based on diatom metrics is an important issue for attaining environmental sustainability. The present study aimed to evaluate differences in the ...diatom–stressor relationship in relatively least disturbed streams in the Konya closed river basin using multivariate analyses and to bio-assess streams by the application of different ecoregional diatom indices.
Cocconeis euglypta
,
Cymbella excisa
,
Cocconeis placentula
, and
Achnanthidium minutissimum
are the most contributing species to the dissimilarity of sampling stations between rainy (spring) and dry (summer and fall) seasons and also between altitude (A2 800- < 1600 m and A3 ≥ 1600 m) groups. The first two axes of canonical correspondence analysis revealed a significant (82.8%) relationship between diatom species and stressors. Diatom species displayed distinct responses to environmental variables (electrical conductivity, Ni, Cu, B, and altitude) playing important roles on the distribution of species. Diatom indices indicate different ecological statuses of stations, from bad to high. European diatom indices except Duero Diatom Index (DDI) and Trophic Diatom Index (TDI) showed good responses to the eco-assessment of streams and indicated high ecological status for the least disturbed sampling stations symbolized as S16, S20, S24, S25, S27-29, S37, and S39. These results were also supported by abiotic evaluation. Although TIT was more competitive in the bio-assessment of streams among diatom indices, it is necessary to increase its species list by determining their trophic weights in future studies. Therefore, the use of ecoregion-specific diatom indices is suggested along with increasing the number of used species to correctly interpret the water quality.
Graphical Abstract
In this study, a statistical analysis was performed on mitotic metaphase chromosomes of 26 Lathyrus taxa, four of which are endemic. ANOVA, correlation analysis, PCA and cluster analysis were ...performed to determine the relationships between taxa based on chromosomal criteria. The morphological similarities of plant taxa and chromosomal statistics results may not be always parallel to each other. According to the findings obtained as a result of analysis, the following taxa, which are close to each other were determined: L. hirsutus - L. odoratus, L. brachypterus var. haussknechtii - L. phaselitanus, L. stenophyllus - L. chloranthus, L. gorgoni var. gorgoni - L. nissolia - L. pratensis, L. tuberosus - L. annuus.
Türkiye is surrounded on three sides by the Mediterranean, Aegean, Marmara, and Black Seas. It has a high biodiversity due to its location between the continents of Europe and Asia. The findings of ...recent monitoring studies conducted under the Water Framework Directive have revealed this diversity. Thus, the concept of developing a new lake phytoplankton composition index has evolved. This study analyzed the results of 2650 phytoplankton samples collected from 491 lakes and reservoirs that were monitored by the T.R. Ministry of Agriculture and Forestry, Directorate General of Water Management. The index used a total of 165 phytoplankton genera. In this context, the PHYTO-TR composition index was developed by analyzing phytoplankton species’ responses to total phosphorus. As a result of the study, the PHYTO-TR and total phosphorus results of the lakes were regressed (
R
2
= 0.4081,
p
< 0.01). Due to the good correlation with total phosphorus, the PHYTO-TR index is regarded as an appropriate instrument for routine phytoplankton assessment according to the Water Framework Directive. Its performance on a larger scale should be evaluated based on its applications in neighboring European and Asian countries.
In order to detect the effects of different stressors on the littoral diatom assemblages and biodiversity of the lentic systems in two different basins in Türkiye, 15 lentic systems in the Akarçay ...and Asi basins were sampled three times (spring, summer, and fall) for littoral diatoms and environmental variables. The biological assessment of these sites was also evaluated using 9 different river and lake diatom indices. Based on the total phosphorus (TP), total nitrogen (TN), electrical conductivity (EC), salinity (SAL) values, and dominant diatom species, three lentic systems in Akarçay Basin (Lake Eber, 26 Ağustos Pond, and Lake Karamık) were more eutrophic and under the pressure of anthropogenic and climatic (precipitation) stressors. Trophic diatom index for lakes (TDIL) showed a higher correlation with TN and TP and was the most effective index in explaining ecological quality in 15 lentic systems. The species richness of diatoms was also negatively affected by EC and SAL values. The lentic systems of the two basins were separated from each other based on the species composition and the distribution of the dominant species with the effect of altitude (ALT). Considering the distribution of diatom assemblage of the lentic systems in these two basins, anthropogenic, climatic, and geographical factors have become prominent to shape the diatom community structure.
Abstract
In order to determine the ecological status of surface waters of different types in a particular ecoregion, the reference conditions for each type should be identified to compare with ...observed conditions, as suggested by the Water Framework Directive (WFD). In this study, 36 candidate reference river sites of the Sakarya Basin (Türkiye) were sampled three times in 2018, and the biological assessment of these sites was evaluated using 18 different diatom indices. In addition, nine different environmental variables were also sampled combined with epilithic diatoms. Based on the canonical correspondence analysis (CCA), alkalinity and pH were determined as the most significant environmental variables for diatom assemblages. Among the diatom indices, Biological Diatom Index (IBD), Artois‐Picardie Diatom Index (IDAP), Descy's Index (DES) and Sládeček's Index (SLA) showed significant correlations with alkalinity and pH according to multiple linear regression (MLR) results. IBD index showed the highest response to the pressures and indicated high or good ecological status of the sampling sites. Moreover, rivers with high water quality status have a high correlation with alkalinity, pH and pollution‐sensitive species. On the other hand, good water quality rivers were highly correlated with total phosphorus and intermediate pollution‐sensitive or pollution‐tolerant species. The 13 reference sites established in this study can be used to assess the ecological status by comparison with the same types of river bodies for further studies in the basins of Türkiye.
In this study, littoral diatoms and environmental variables were sampled three times in 2017 (spring, summer, and autumn) to determine the effect of salinity (SAL) and altitude (ALT) on the littoral ...diatom assemblages (composition, distribution, species richness and diversity) of 12 lentic systems in the Western Mediterranean Basin. Due to the SAL and ALT differences in these systems, they were distinguished under two groups (high elevated freshwater lentic systems HEF and hyposaline lentic systems HYP). The Bray–Curtis and Canonical Correspondence (CCA) analyses based on diatom species also confirmed this separation. In HYP, SAL and alkalinity (ALK) were the most effective parameters on diatom assemblage. On the other hand, diatom assemblage was mainly affected by ALT in HEF. For the biological assessment of these systems, seven diatom indices were implemented. Although most of the indices showed higher regression with SAL and ALT, they did not give the intended result in the evaluation of HYP. On the other hand, the most consistent index with environmental variables and dominant species in HEF was the Generic Diatom Index (IDG).
This study is the first attempt to evaluate the limno-ecological status of freshwater ecosystems in Aras River system (Turkey) using diatom metrics and multivariate analyses according to the European ...Union Water Framework Directive requirements. Samples were collected using the standard protocols from 17 sampling stations in August and October of 2014, and June of 2015. Deterioration of water quality in the Aras River catchment was remarked from the downstream of Karakoyunlu, Sarısu, and Bozkuş creeks, which showed higher values of trophic index Turkey (TIT), trophic index (TI), and eutrophication and/or pollution index-diatom (EPI-D). These sites were also characterized by pollution tolerant taxa e.g.,
Cocconeis placentula
,
Gomphonema parvulum
,
Navicula cryptocephala
,
Navicula trivialis
, and
Tryblionella angustata
. Sites S14–S17 had high ecological status according to TIT, supported by the score of EPI-D which indicated a good ecological condition for S14. The occurrence of pollution-sensitive species (e.g.,
Hannaea arcus
,
Cymbella affinis
,
Didymosphenia geminata
,
Meridion circulare
, and
Encyonema silesiacum
) and the low nutrients like total phosphorus, orthophosphate and nitrate, conductivity, and BOD
5
supported the high ecological status of S14–S17. The relationships between diatom assemblages and environmental variables were also illustrated by multivariate analyses. Spearman correlation analysis revealed that TIT had positive important correlations with total phosphorus (
p
< 0.01,
r
= 0.768). Trophic index and EPI-D had also significant correlations with environmental variables, but they had lower correlation coefficient than that of TIT. It seems that TIT could be a suitable diatom metric for assessing the ecological status of sampling stations in Aras River system and Mediterranean region. Our findings showed also that ecological statuses of surface waters should be evaluated due to the indices developed in their ecoregions.
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