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Dr. Konstantinos Stefanidis
Hellenic Centre for Marine Research

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0 Freshwater Ecology
0 Limnology
0 Water Resource Management
0 Aquatic macrophytes
0 hydromorphological alterations

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Aquatic macrophytes
hydromorphological alterations

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Journal article
Published: 26 July 2021 in Journal of Environmental Management
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Aquatic and riparian plants play a crucial role in the functioning of riverine ecosystems. Hence, analyzing multiple facets of plant diversity could be extremely useful for assessing the ecological integrity of lotic ecosystems. The main objective of this study was to investigate the response of multiple facets of aquatic plant diversity, such as species richness, taxonomic distinctness and compositional dissimilarity, to environmental factors (i.e. nutrient pollution and hydromorphological alteration) in 72 stream reaches of mainland Greece. We employed Generalized Additive Models to identify the variables with the highest influence and examine the response of species richness and taxonomic distinctness to environmental gradients. The relationship between compositional dissimilarity and the environment was examined with Generalized Dissimilarity Modelling. Our results supported our hypothesis that human disturbances play a considerable role in shaping macrophyte assemblages. In particular, phosphates and hydromorphological modification were significant predictors of species richness, whereas taxonomic distinctness was unaffected by indicators of anthropogenic stress but it was influenced mostly by elevation, water temperature and pH. Concerning the compositional dissimilarity, geographic distance, elevation, temperature and total inorganic nitrogen were the most important environmental parameters. Our findings suggest that human stressors, such as hydromorphological modification and nutrient enrichment, affect the plant species richness at stream reach scale, but when considering community composition or taxonomic distinctness, environmental factors associated with the natural variability (e.g. elevation, temperature and geographic distance) are of higher importance. Overall, our results emphasize the advantage of examining multiple aspects of diversity when designing conservation schemes and management plans for riparian areas.

ACS Style

Konstantinos Stefanidis; Anthi Oikonomou; Eva Papastergiadou. Responses of different facets of aquatic plant diversity along environmental gradients in Mediterranean streams: Results from rivers of Greece. Journal of Environmental Management 2021, 296, 113307 .

AMA Style

Konstantinos Stefanidis, Anthi Oikonomou, Eva Papastergiadou. Responses of different facets of aquatic plant diversity along environmental gradients in Mediterranean streams: Results from rivers of Greece. Journal of Environmental Management. 2021; 296 ():113307.

Chicago/Turabian Style

Konstantinos Stefanidis; Anthi Oikonomou; Eva Papastergiadou. 2021. "Responses of different facets of aquatic plant diversity along environmental gradients in Mediterranean streams: Results from rivers of Greece." Journal of Environmental Management 296, no. : 113307.

Journal article
Published: 04 June 2021 in Water
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Artificial Neural Networks (ANNs) have wide applications in aquatic ecology and specifically in modelling water quality and biotic responses to environmental predictors. However, data scarcity is a common problem that raises the need to optimize modelling approaches to overcome data limitations. With this paper, we investigate the optimal k-fold cross validation in building an ANN using a small water-quality data set. The ANN was created to model the chlorophyll-a levels of a shallow eutrophic lake (Mikri Prespa) located in N. Greece. The typical water quality parameters serving as the ANN’s inputs are pH, dissolved oxygen, water temperature, phosphorus, nitrogen, electric conductivity, and Secchi disk depth. The available data set was small, containing only 89 data samples. For that reason, k-fold cross validation was used for training the ANN. To find the optimal k value for the k-fold cross validation, several values of k were tested (ranging from 3 to 30). Additionally, the leave-one-out (LOO) cross validation, which is an extreme case of the k-fold cross validation, was also applied. The ANN’s performance indices showed a clear trend to be improved as the k number was increased, while the best results were calculated for the LOO cross validation as expected. The computational times were calculated for each k value, where it was found the computational time is relatively low when applying the more expensive LOO cross validation; therefore, the LOO is recommended. Finally, a sensitivity analysis was examined using the ANN to investigate the interactions of the input parameters with the Chlorophyll-a, and hence examining the potential use of the ANN as a water management tool for nutrient control.

ACS Style

Ekaterini Hadjisolomou; Konstantinos Stefanidis; Herodotos Herodotou; Michalis Michaelides; George Papatheodorou; Eva Papastergiadou. Modelling Freshwater Eutrophication with Limited Limnological Data Using Artificial Neural Networks. Water 2021, 13, 1590 .

AMA Style

Ekaterini Hadjisolomou, Konstantinos Stefanidis, Herodotos Herodotou, Michalis Michaelides, George Papatheodorou, Eva Papastergiadou. Modelling Freshwater Eutrophication with Limited Limnological Data Using Artificial Neural Networks. Water. 2021; 13 (11):1590.

Chicago/Turabian Style

Ekaterini Hadjisolomou; Konstantinos Stefanidis; Herodotos Herodotou; Michalis Michaelides; George Papatheodorou; Eva Papastergiadou. 2021. "Modelling Freshwater Eutrophication with Limited Limnological Data Using Artificial Neural Networks." Water 13, no. 11: 1590.

Research article
Published: 24 March 2021 in Inland Waters
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Interactions between stressors in freshwater ecosystems, including those associated with climate change and nutrient enrichment, are currently difficult to detect and manage. Our understanding of the forms and frequency of occurrence of such interactions is limited; assessments using field data have been constrained as a result of varying data forms and quality. To address this issue, we demonstrate a statistical approach capable of assessing multiple stressor interactions using contrasting data forms in 3 European catchments (Loch Leven Catchment, UK: assessment of phytoplankton response in a single lake with time series data; Pinios Catchment, Greece: macroinvertebrate response across multiple rivers using spatial data; and Lepsämänjoki Catchment, Finland: phytoplankton response across multiple rivers using spatiotemporal data). Statistical models were developed to predict the relative and interactive effects of climate change and nutrient enrichment sensitive indicators (stressors) on indicators of ecological quality (ecological responses) within the framework of linear mixed effects models. In all catchments, indicators of nutrient enrichment were identified as the primary stressor, with climate change-sensitive indicators causing secondary effects (Loch Leven: additive, total phosphorus [TP] × precipitation; Pinios: additive, nitrate × dissolved oxygen; Lepsämänjoki: synergistic, TP × summer water temperature), the intensity of which varied between catchments and along the nutrient stressor gradient. Simple stressor change scenarios were constructed for each catchment and used in combination with mechanistic models to explore potential management responses. This approach can be used to explore the need for multiple stressor management in freshwaters, helping practitioners navigate a complex world of environmental change.

ACS Style

Bryan M. Spears; Daniel Chapman; Laurence Carvalho; Katri Rankinen; Konstantinos Stefanidis; Stephen Ives; Kristiina Vuorio; Sebastian Birk. Assessing multiple stressor effects to inform climate change management responses in three European catchments. Inland Waters 2021, 1 -13.

AMA Style

Bryan M. Spears, Daniel Chapman, Laurence Carvalho, Katri Rankinen, Konstantinos Stefanidis, Stephen Ives, Kristiina Vuorio, Sebastian Birk. Assessing multiple stressor effects to inform climate change management responses in three European catchments. Inland Waters. 2021; ():1-13.

Chicago/Turabian Style

Bryan M. Spears; Daniel Chapman; Laurence Carvalho; Katri Rankinen; Konstantinos Stefanidis; Stephen Ives; Kristiina Vuorio; Sebastian Birk. 2021. "Assessing multiple stressor effects to inform climate change management responses in three European catchments." Inland Waters , no. : 1-13.

Journal article
Published: 23 March 2021 in Hydrology
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Riparian zones play an important role in the ecological stability of rivers. In particular, the quality of the riparian vegetation is a significant component of the hydromorphological status. In Europe, the QBR index (Qualitat del Bosc de Ribera) and the River Habitat Survey (RHS) are commonly used for the qualitative assessment of the riparian vegetation. In this study, we estimated the QBR index and the Riparian Quality index, which is derived from the RHS method, for 123 river reaches of the National Monitoring Network of Greece. Our field work included the completion of RHS and QBR protocols, as well as the use of Unmanned Aerial Vehicles (UAVs). The aim of this study is to assess the riparian vegetation status and to identify linkages with the dominant land uses within the catchment. Correlation analysis was used to identify the relationships between hydromorphological alterations and the degradation of the riparian vegetation, as well as their connection to land uses in the catchment area. Our results highlighted severe modifications of the riparian vegetation for the majority of the studied reaches. We also showed a differentiation of the QBR with respect to changes in the altitude and the land uses in the catchment area. Overall QBR reflects the variation in the riparian vegetation quality better than RQI. Our findings constitute an assessment of the status of the riparian zones in Greek rivers and set the basis for further research for the development of new and effective tools for a rapid quality assessment of the riparian zones.

ACS Style

Anna Latsiou; Theodora Kouvarda; Konstantinos Stefanidis; George Papaioannou; Konstantinos Gritzalis; Elias Dimitriou. Pressures and Status of the Riparian Vegetation in Greek Rivers: Overview and Preliminary Assessment. Hydrology 2021, 8, 55 .

AMA Style

Anna Latsiou, Theodora Kouvarda, Konstantinos Stefanidis, George Papaioannou, Konstantinos Gritzalis, Elias Dimitriou. Pressures and Status of the Riparian Vegetation in Greek Rivers: Overview and Preliminary Assessment. Hydrology. 2021; 8 (1):55.

Chicago/Turabian Style

Anna Latsiou; Theodora Kouvarda; Konstantinos Stefanidis; George Papaioannou; Konstantinos Gritzalis; Elias Dimitriou. 2021. "Pressures and Status of the Riparian Vegetation in Greek Rivers: Overview and Preliminary Assessment." Hydrology 8, no. 1: 55.

Journal article
Published: 15 March 2021 in Water Research
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Understanding the climatic drivers of eutrophication is critical for lake management under the prism of the global change. Yet the complex interplay between climatic variables and lake processes makes prediction of phytoplankton biomass a rather difficult task. Quantifying the relative influence of climate-related variables on the regulation of phytoplankton biomass requires modelling approaches that use extensive field measurements paired with accurate meteorological observations. In this study we used climate and lake related variables obtained from the ERA5-Land reanalysis dataset combined with a large dataset of in-situ measurements of chlorophyll-a and phytoplankton biomass from 50 water bodies to develop models of phytoplankton related responses as functions of the climate reanalysis data. We used chlorophyll-a and phytoplankton biomass as response metrics of phytoplankton growth and we employed two different modelling techniques, boosted regression trees (BRT) and generalized additive models for location scale and shape (GAMLSS). According to our results, the fitted models had a relatively high explanatory power and predictive performance. Boosted regression trees had a high pseudo R2 with the type of the lake, the total layer temperature, and the mix-layer depth being the three predictors with the higher relative influence. The best GAMLSS model retained mix-layer depth, mix-layer temperature, total layer temperature, total runoff and 10-m wind speed as significant predictors (p<0.001). Regarding the phytoplankton biomass both modelling approaches had less explanatory power than those for chlorophyll-a. Concerning the predictive performance of the models both the BRT and GAMLSS models for chlorophyll-a outperformed those for phytoplankton biomass. Overall, we consider these findings promising for future limnological studies as they bring forth new perspectives in modelling ecosystem responses to a wide range of climate and lake variables. As a concluding remark, climate reanalysis can be an extremely useful asset for lake research and management.

ACS Style

Konstantinos Stefanidis; George Varlas; Aikaterini Vourka; Anastasios Papadopoulos; Elias Dimitriou. Delineating the relative contribution of climate related variables to chlorophyll-a and phytoplankton biomass in lakes using the ERA5-Land climate reanalysis data. Water Research 2021, 196, 117053 .

AMA Style

Konstantinos Stefanidis, George Varlas, Aikaterini Vourka, Anastasios Papadopoulos, Elias Dimitriou. Delineating the relative contribution of climate related variables to chlorophyll-a and phytoplankton biomass in lakes using the ERA5-Land climate reanalysis data. Water Research. 2021; 196 ():117053.

Chicago/Turabian Style

Konstantinos Stefanidis; George Varlas; Aikaterini Vourka; Anastasios Papadopoulos; Elias Dimitriou. 2021. "Delineating the relative contribution of climate related variables to chlorophyll-a and phytoplankton biomass in lakes using the ERA5-Land climate reanalysis data." Water Research 196, no. : 117053.

Journal article
Published: 13 July 2020 in Water
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Disentangling the main drivers of species richness and community composition is a central theme in ecology. Freshwater biodiversity patterns have been poorly explored; yet, it has been shown that different freshwater biota have different, often contrasting responses to environmental gradients. In this study, we investigated the relative contribution of geographical and environmental (habitat-, climate- and water quality-related) factors/gradients in shaping the α- and β-diversity patterns of macrophytes and fish in sixteen natural freshwater lakes of an unexplored Balkan biodiversity hotspot, the Southern Balkan Peninsula. We employed generalized linear modeling to identify drivers of α-diversity, and generalized dissimilarity modeling to explore commonalities and dissimilarities of among-biota β-diversity. Species richness of both biota was significantly associated with lake surface area, whereas macrophytes had an inverse response to altitude, compared to fish. Both species turnover and nestedness significantly contributed to the total β-diversity of macrophytes. In contrast, species turnover was the most significant contributor to the total fish β-diversity. We found that the compositional variation of macrophytes is primarily limited by dispersal and ultimately shaped by environmental drivers, resulting in spatially structured assemblages. Fish communities were primarily shaped by altitude, highlighting the role of species sorting. We conclude that among-biota diversity patterns are shaped by different/contrasting factors, and, thus, effective/sustainable conservation strategies should encompass multiple aquatic biota.

ACS Style

Anthi Oikonomou; Konstantinos Stefanidis. α- and β-Diversity Patterns of Macrophytes and Freshwater Fishes are Driven by Different Factors and Processes in Lakes of the Unexplored Southern Balkan Biodiversity Hotspot. Water 2020, 12, 1984 .

AMA Style

Anthi Oikonomou, Konstantinos Stefanidis. α- and β-Diversity Patterns of Macrophytes and Freshwater Fishes are Driven by Different Factors and Processes in Lakes of the Unexplored Southern Balkan Biodiversity Hotspot. Water. 2020; 12 (7):1984.

Chicago/Turabian Style

Anthi Oikonomou; Konstantinos Stefanidis. 2020. "α- and β-Diversity Patterns of Macrophytes and Freshwater Fishes are Driven by Different Factors and Processes in Lakes of the Unexplored Southern Balkan Biodiversity Hotspot." Water 12, no. 7: 1984.

Journal article
Published: 27 May 2020 in Water
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Reduction of nutrient loadings is often prioritized among other management measures for improving the water quality of freshwaters within the catchment. However, urban point sources and agriculture still thrive as the main drivers of nitrogen and phosphorus pollution in European rivers. With this article we present a nationwide assessment of nitrogen and phosphorus loads that 18 large rivers in Greece receive with the purpose to assess variability among seasons, catchments, and river types and distinguish relationships between loads and land uses of the catchment. We employed an extensive dataset of 636 field measurements of nutrient concentrations and river discharges to calculate nitrogen and phosphorus loads. Descriptive statistics and a cluster analysis were conducted to identify commonalties and differences among catchments and seasons. In addition a network analysis was conducted and its modularity feature was used to detect commonalities among rivers and sampling sites with regard to their nutrient loads. A correlation analysis was used to identify major possible connections between types of land uses and nutrient loads. The results indicated that the rivers Alfeios, Strymonas, and Aliakmonas receive the highest inorganic nitrogen loads while the highest inorganic phosphorus loads were calculated for the rivers Strymonas, Aliakmonas, and Axios. Concerning the temporal variation of loads, inorganic nitrogen presented a peak on March and gradually declined until October when the dry period typically ends for most regions of Greece. Inorganic phosphorus loads had the highest average value in August and the lowest in October. Thus, our findings confirmed the presence of a typical seasonal variation in nitrogen loads that follows the seasonality in hydrology where high surface runoff during the wet months contribute to higher river discharges and higher nitrogen loads from the catchment. On the contrary, high phosphorus loads persisted during dry months that could be attributed to a dilution effect. Furthermore, the results imply a clear connection between agriculture and both nitrogen and phosphorus. Overall, this work presents extensive information on the nitrogen and phosphorus loads that major rivers in Greece receive that can largely aid water managers to adapt and revise basin management plans in accordance with agricultural management (e.g., which months farmers should reduce the use of fertilizers) with the purpose of meeting the environmental targets defined by the Water Framework Directive (WFD).

ACS Style

Konstantinos Stefanidis; Aikaterini Christopoulou; Serafeim Poulos; Emmanouil Dassenakis; Elias Dimitriou. Nitrogen and Phosphorus Loads in Greek Rivers: Implications for Management in Compliance with the Water Framework Directive. Water 2020, 12, 1531 .

AMA Style

Konstantinos Stefanidis, Aikaterini Christopoulou, Serafeim Poulos, Emmanouil Dassenakis, Elias Dimitriou. Nitrogen and Phosphorus Loads in Greek Rivers: Implications for Management in Compliance with the Water Framework Directive. Water. 2020; 12 (6):1531.

Chicago/Turabian Style

Konstantinos Stefanidis; Aikaterini Christopoulou; Serafeim Poulos; Emmanouil Dassenakis; Elias Dimitriou. 2020. "Nitrogen and Phosphorus Loads in Greek Rivers: Implications for Management in Compliance with the Water Framework Directive." Water 12, no. 6: 1531.

Journal article
Published: 08 April 2020 in Hydrology
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The Water Framework Directive (WFD) requires from member states to monitor hydromorphological features of rivers in order to assess their ecological quality. Thus, numerous hydromorphological assessment methods have been developed with most of them focusing on the dynamics of hydrology, geomorphology and riparian zone extent. Within the scope of this study, we assessed the hydromorphological features of 106 river reaches distributed among thirteen WFD River Basin Districts (RBDs) to identify the main drivers of hydromorphological perturbation at a national scale. The studied reaches reflect a wide range of natural variability as they include various types of watercourses extending from lowlands to mid-altitude and mountainous systems. We employed the River Habitat Survey (RHS), and we recorded hydromorphological features and modifications in both banks and the channel bed along 500 m for each reach. Then, the Habitat Modification Score (HMS) and the individual sub-scores that indicate the extent of specific modifications (e.g., bridges, fords, weirs, bank reprofiling, bank reinforcement, etc.) were calculated in order to a) assess the severity of the total artificial modification and b) to highlight the most common and severe causes of overall alteration. The results showed that alterations such as reprofiling and reinforcement of banks contributed the most to the total HMS followed by the presence of fords and bridges. Particularly, the bank alterations indicate a serious deterioration of the longitudinal profile of the reaches, while the occurrence of many fords and bridges is the main cause for perturbations that affect locally the stream cross-sectional profile. Overall, these results compile a first nationwide assessment of the hydromorphological status of Greek rivers in line with the WFD and set the basis for further research that will focus on the diversity of stream habitat features as a measure for the overall ecological quality.

ACS Style

Konstantinos Stefanidis; Anna Latsiou; Theodora Kouvarda; Anastasia Lampou; Nektarios Kalaitzakis; Konstantinos Gritzalis; Elias Dimitriou. Disentangling the Main Components of Hydromorphological Modifications at Reach Scale in Rivers of Greece. Hydrology 2020, 7, 22 .

AMA Style

Konstantinos Stefanidis, Anna Latsiou, Theodora Kouvarda, Anastasia Lampou, Nektarios Kalaitzakis, Konstantinos Gritzalis, Elias Dimitriou. Disentangling the Main Components of Hydromorphological Modifications at Reach Scale in Rivers of Greece. Hydrology. 2020; 7 (2):22.

Chicago/Turabian Style

Konstantinos Stefanidis; Anna Latsiou; Theodora Kouvarda; Anastasia Lampou; Nektarios Kalaitzakis; Konstantinos Gritzalis; Elias Dimitriou. 2020. "Disentangling the Main Components of Hydromorphological Modifications at Reach Scale in Rivers of Greece." Hydrology 7, no. 2: 22.

Journal article
Published: 01 February 2020 in Journal of Ecological Engineering
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Urbanization of stream ecosystems with the purpose of managing flash-flood events is considered nowadays responsible for habitat loss and alteration of the natural flow regime with severe implications for the ecosystem functioning. Not surprisingly river scientists have started seeking...

ACS Style

Olga Ourloglou; Konstantinos Stefanidis; Elias Dimitriou. Assessing Nature-Based and Cassical Engineering Solutions for Flood-Risk Reduction in Urban Streams. Journal of Ecological Engineering 2020, 21, 46 -56.

AMA Style

Olga Ourloglou, Konstantinos Stefanidis, Elias Dimitriou. Assessing Nature-Based and Cassical Engineering Solutions for Flood-Risk Reduction in Urban Streams. Journal of Ecological Engineering. 2020; 21 (2):46-56.

Chicago/Turabian Style

Olga Ourloglou; Konstantinos Stefanidis; Elias Dimitriou. 2020. "Assessing Nature-Based and Cassical Engineering Solutions for Flood-Risk Reduction in Urban Streams." Journal of Ecological Engineering 21, no. 2: 46-56.

Conference paper
Published: 12 November 2019 in Proceedings of 4th International Electronic Conference on Water Sciences
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The Water Framework Directive (WFD) requires from member states to monitor hydromorphological features of rivers in order to assess their ecological quality. Thus, numerous hydromorphological assessment methods have been developed with most of them focusing on the dynamics of hydrology, geomorphology and riparian zone extent. Within the scope of this study, we assessed the hydromorphological features of more than 100 river reaches distributed among fourteen WFD River Basin Districts (RBDs) to identify the main drivers of hydromorphological perturbation. We employed the River Habitat Survey (RHS) and we recorded hydromorphological features and modifications in both banks and the channel bed along 500 m for each reach. Then, the Habitat Modification Score (HMS) and the individual sub-scores that indicate the extent of specific modifications (e.g. bridges, fords, weirs, bank reprofiling, bank reinforcement etc) were calculated in order to a) assess the severity of the total artificial modification and b) to highlight the most common and severe causes of longitudinal and cross-sectional alterations. The results showed that alterations such as reprofiling and reinforcement of banks, contributed the most to the total HMS followed by the presence of bridges. Particularly the bank alterations indicate a serious deterioration of the longitudinal profile of the reaches while the occurrence of many small and larger bridges is the main cause for perturbations that affect the stream cross-sectional profile. Overall, these results compile a first nationwide assessment of the hydromorphological status of Greek rivers in line with the WFD and set the basis for further research that will focus on the diversity of stream habitat features as a measure for the overall ecological quality.

ACS Style

Konstantinos Stefanidis; Konstantinos Gritzalis; Theodora Kouvarda; Anna Latsiou; Anastasia Lampou; Elias Dimitriou. Untangling The Main Drivers Of Hydromorphological Alteration In Greek Rivers. Proceedings of 4th International Electronic Conference on Water Sciences 2019, 1 .

AMA Style

Konstantinos Stefanidis, Konstantinos Gritzalis, Theodora Kouvarda, Anna Latsiou, Anastasia Lampou, Elias Dimitriou. Untangling The Main Drivers Of Hydromorphological Alteration In Greek Rivers. Proceedings of 4th International Electronic Conference on Water Sciences. 2019; ():1.

Chicago/Turabian Style

Konstantinos Stefanidis; Konstantinos Gritzalis; Theodora Kouvarda; Anna Latsiou; Anastasia Lampou; Elias Dimitriou. 2019. "Untangling The Main Drivers Of Hydromorphological Alteration In Greek Rivers." Proceedings of 4th International Electronic Conference on Water Sciences , no. : 1.

Journal article
Published: 13 August 2019 in Water
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European rivers are under ecological threat by a variety of stressors. Nutrient pollution, soil erosion, and alteration in hydrology are considered the most common problems that riverine ecosystems are facing today. Not surprisingly, river monitoring activities in Europe have been intensified during the last few years to fulfil the Water Framework Directive (WFD) requirements. With this article, we present a nationwide assessment of the water quality and hydromorphological variability in Greek Rivers based on the results of the national monitoring program under the WFD. Water quality and hydromorphological data from 352 sites belonging to 221 rivers were explored with principal component analysis (PCA) to identify main environmental gradients and the variables that contribute the most to the total variance. Nitrate, phosphate, ammonium and electrical conductivity were identified as the most important water chemistry parameters, and typical vector-based spatial data analysis was applied to map their spatial distribution at sub-basin scale. In addition, we conducted simple linear models between the aforementioned parameters and the share of land uses within the basin of each sampling site in order to identify significant relationships. Agriculture was the most important land use affecting the nitrate and electrical conductivity, while artificial surfaces were the best predictor for phosphate and ammonium. Concerning the hydromorphological variability, fine types of substrate and discharge were the variables with the highest contribution to the total variance. Overall, the results of this article can be used for the preliminary assessment of susceptible areas/rivers to high levels of nutrient pollution that can aid water managers to formulate recommendations for improvement of further monitoring activities. Furthermore, our findings implicate the need for enhancement of agri-environmental measures and reduction of point-source pollution in disturbed areas to avert the risk of further environmental degradation under the anticipated global change.

ACS Style

Konstantinos Stefanidis; George Papaioannou; Vassiliki Markogianni; Elias Dimitriou. Water Quality and Hydromorphological Variability in Greek Rivers: A Nationwide Assessment with Implications for Management. Water 2019, 11, 1680 .

AMA Style

Konstantinos Stefanidis, George Papaioannou, Vassiliki Markogianni, Elias Dimitriou. Water Quality and Hydromorphological Variability in Greek Rivers: A Nationwide Assessment with Implications for Management. Water. 2019; 11 (8):1680.

Chicago/Turabian Style

Konstantinos Stefanidis; George Papaioannou; Vassiliki Markogianni; Elias Dimitriou. 2019. "Water Quality and Hydromorphological Variability in Greek Rivers: A Nationwide Assessment with Implications for Management." Water 11, no. 8: 1680.

Journal article
Published: 20 May 2019 in Water
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Freshwater ecologists have shown increased interest in assessing biotic responses to environmental change using functional community characteristics. With this article, we investigate the potential of using functional traits of the aquatic plants to assess eutrophication in freshwater lakes. To this end we collected macrophyte and physicochemical data from thirteen lakes in Greece and we applied a trait-based analysis to first identify discrete groups of macrophytes that share common functional traits and then to assess preliminary responses of these groups to water quality gradients. We allocated 11 traits that cover mostly growth form and morphological characteristics to a total of 33 macrophyte species. RLQ and fourth corner analysis were employed to explore potential relationships between species, trait composition and environmental gradients. In addition, a hierarchical cluster analysis was conducted to discriminate groups of plants that share common trait characteristics and then the position of the groups along the environmental gradients was assessed. The results showed total phosphorus, chlorophyll-a, conductivity, pH and Secchi disk depth as main drivers of the environmental gradients. Hierarchical cluster analysis showed a clear separation of macrophyte assemblages with discrete functional characteristics that appeared to associate with different environmental drivers. Thus, rooted submerged plants were related with higher Secchi disk depth, conductivity and alkalinity whereas rooted floating-leaved plants showed a preference for enriched waters with phosphorus and nitrogen. In addition, free-floating plants were related positively with nitrogen and increased pH. Although we did not identify specific trait patterns with environmental drivers, our findings indicate a differentiation of macrophytes based on their functional characteristics along water quality gradients. Overall, the presented results are encouraging for conducting future monitoring studies in lakes focused on the functional plant trait composition, as expanding the current approach to additional lakes and using quantifiable functional characteristics will provide more insight about the potential of trait-based approaches as ecological assessment systems.

ACS Style

Konstantinos Stefanidis; Eva Papastergiadou. Linkages between Macrophyte Functional Traits and Water Quality: Insights from a Study in Freshwater Lakes of Greece. Water 2019, 11, 1047 .

AMA Style

Konstantinos Stefanidis, Eva Papastergiadou. Linkages between Macrophyte Functional Traits and Water Quality: Insights from a Study in Freshwater Lakes of Greece. Water. 2019; 11 (5):1047.

Chicago/Turabian Style

Konstantinos Stefanidis; Eva Papastergiadou. 2019. "Linkages between Macrophyte Functional Traits and Water Quality: Insights from a Study in Freshwater Lakes of Greece." Water 11, no. 5: 1047.

Journal article
Published: 05 April 2019 in Water
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The hydrologic regime of a river is one of the factors determining its ecological status. This paper tries to indicate the present hydrologic stress occurring across European rivers on the basis of model integration. This results in a pan-European assessment at the resolution of the functional elementary catchment (FEC), based on simulated daily time-series of river flows from the model PCR-GLOBWB. To estimate proxies of the present hydrologic stress, two datasets of river flow were simulated under the same climate, one from a hypothetic least disturbed condition scenario and the second from the anthropogenic scenario with the actual water management occurring. Indicators describing the rivers’ hydrologic regime were calculated with the indicators of hydrologic alteration (IHA) software package and the river total mean flow and the relative baseflow magnitude over the total flow were used to express the deviations between the two scenarios as proxy metrics of rivers’ hydrologic alteration or hydrologic stress. The alteration results on Europe’s FEC-level background showed that Southern Europe is more hydrologically stressed than the rest of Europe, with greater potential for hydrology to be clearly associated with river segments of unreached good ecological status and high basin management needs.

ACS Style

Yiannis Panagopoulos; Kostas Stefanidis; Marta Faneca Sanchez; Frederiek Sperna Weiland; Rens Van Beek; Markus Venohr; Lidija Globevnik; Maria Mimikou; Sebastian Birk. Pan-European Calculation of Hydrologic Stress Metrics in Rivers: A First Assessment with Potential Connections to Ecological Status. Water 2019, 11, 703 .

AMA Style

Yiannis Panagopoulos, Kostas Stefanidis, Marta Faneca Sanchez, Frederiek Sperna Weiland, Rens Van Beek, Markus Venohr, Lidija Globevnik, Maria Mimikou, Sebastian Birk. Pan-European Calculation of Hydrologic Stress Metrics in Rivers: A First Assessment with Potential Connections to Ecological Status. Water. 2019; 11 (4):703.

Chicago/Turabian Style

Yiannis Panagopoulos; Kostas Stefanidis; Marta Faneca Sanchez; Frederiek Sperna Weiland; Rens Van Beek; Markus Venohr; Lidija Globevnik; Maria Mimikou; Sebastian Birk. 2019. "Pan-European Calculation of Hydrologic Stress Metrics in Rivers: A First Assessment with Potential Connections to Ecological Status." Water 11, no. 4: 703.

Journal article
Published: 06 February 2019 in Water
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The metabolic balance between gross primary production (GPP) and ecosystem respiration (R) is known to display large spatial and temporal variations within shallow lakes. Thus, although estimation of aquatic metabolism using free-water measurements of dissolved oxygen concentration has become increasingly common, the explanation of the variance in the metabolic regime remains an extremely difficult task. In this study, rates of GPP, respiration (R) and the metabolic balance (net ecosystem production, NEP) were estimated in four littoral habitats with different macrophyte growth forms (floating-leaved vs submerged) over a 28-month period in lake of Kastoria (Greece), a shallow eutrophic lake. Our results showed that net heterotrophy prevailed over the studied period, suggesting that allochthonous organics fuel respiration processes in the littoral. Temporal variation in the metabolic rates was driven mainly by the seasonal variation in irradiance and water temperature, with the peak of metabolic activity occurring in summer and early autumn. Most importantly, significant spatial variation among the four habitats was observed and associated with the different macrophyte growth forms that occurred in the sites. The results highlight the importance of habitat specific characteristics for the assessment of metabolic balance and underline the potentially high contribution of littoral habitats to the whole lake metabolism.

ACS Style

Konstantinos Stefanidis; Elias Dimitriou. Differentiation in Aquatic Metabolism between Littoral Habitats with Floating-Leaved and Submerged Macrophyte Growth Forms in a Shallow Eutrophic Lake. Water 2019, 11, 287 .

AMA Style

Konstantinos Stefanidis, Elias Dimitriou. Differentiation in Aquatic Metabolism between Littoral Habitats with Floating-Leaved and Submerged Macrophyte Growth Forms in a Shallow Eutrophic Lake. Water. 2019; 11 (2):287.

Chicago/Turabian Style

Konstantinos Stefanidis; Elias Dimitriou. 2019. "Differentiation in Aquatic Metabolism between Littoral Habitats with Floating-Leaved and Submerged Macrophyte Growth Forms in a Shallow Eutrophic Lake." Water 11, no. 2: 287.

Special issue article
Published: 16 December 2018 in Aquatic Conservation: Marine and Freshwater Ecosystems
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Aquatic macrophytes play a key role in lake dynamics, but human activities and eutrophication have resulted in macrophyte loss in many lakes throughout Europe. In this study, the relationships between aquatic macrophytes and gradients of environmental factors were explored using an extensive set of data collected from 13 lakes of the Greek mainland that are part of the European network Natura 2000. The main objectives were to assess the importance of key abiotic predictors and estimate possible environmental thresholds of macrophyte richness, diversity, and abundance using boosted regression trees (BRTs), as well as to explore further the distribution of dominant macrophyte taxa along environmental gradients. The results reveal conductivity as a significant predictor of macrophyte total cover and diversity. In addition, orthophosphate and nitrate nitrogen appear to play an important role for several macrophyte species and assemblages, reflecting a major effect of eutrophication on the distribution of taxa. The majority of macrophyte assemblages were found in waters characterized by high nutrient content, although their distribution extends along a wide range of phosphorus and nitrogen concentration. In contrast, charophyte species show the optimum of their distribution in clear, oligotrophic waters. This integrated study can be used for ranking environmental factors that influence macrophyte distribution in the lakes of Greece and for identifying taxa or macrophyte assemblages that can be used as effective indicators of changes in the abiotic environment. In addition, the results can contribute to the conservation of freshwater habitats in the protected areas studied. In particular, measures that aim to improve water quality are expected also to restore oligotrophic habitats that are characterized by benthic charophyte vegetation. Overall, the links between macrophyte assemblages and abiotic factors are critically important in improving freshwater biodiversity management and environmental policies in east Mediterranean lakes.

ACS Style

Konstantinos Stefanidis; Maria Sarika; Eva Papastegiadou. Exploring environmental predictors of aquatic macrophytes in water‐dependent Natura 2000 sites of high conservation value: Results from a long‐term study of macrophytes in Greek lakes. Aquatic Conservation: Marine and Freshwater Ecosystems 2018, 29, 1133 -1148.

AMA Style

Konstantinos Stefanidis, Maria Sarika, Eva Papastegiadou. Exploring environmental predictors of aquatic macrophytes in water‐dependent Natura 2000 sites of high conservation value: Results from a long‐term study of macrophytes in Greek lakes. Aquatic Conservation: Marine and Freshwater Ecosystems. 2018; 29 (7):1133-1148.

Chicago/Turabian Style

Konstantinos Stefanidis; Maria Sarika; Eva Papastegiadou. 2018. "Exploring environmental predictors of aquatic macrophytes in water‐dependent Natura 2000 sites of high conservation value: Results from a long‐term study of macrophytes in Greek lakes." Aquatic Conservation: Marine and Freshwater Ecosystems 29, no. 7: 1133-1148.

Journal article
Published: 01 June 2018 in Science of The Total Environment
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Streams and rivers are among the most threatened ecosystems in Europe due to the combined effects of multiple pressures related to anthropogenic activities. Particularly in the Mediterranean region, changes in hydromorphology along with increased nutrient loadings are known to affect the ecological functions and ecosystem services of streams and rivers with the anticipated climate change being likely to further impair their functionality and structure. In this study, we investigated the combined effects of agricultural driven stressors on the ecology and delivered services of the Pinios river basin in Greece under three future world scenarios developed within the EU funded MARS project. Scenarios are based on combinations of Representative Concentration Pathways and Shared Socioeconomic Pathways and refer to early century (2030) and mid-century (2060) representing future climate worlds with particular socioeconomic characteristics. To assess the responses of ecological and ecosystem service indicators to the scenarios we first simulated hydrology and water quality in Pinios with a process-based model. Simulated abiotic stressor parameters (predictors) were linked to two biotic indicators, the macroinvertebrate indicators ASPT and EPT, with empirical modelling based on boosted regression trees and general linear models. Our results showed that the techno world scenario driven by fast economic growth and intensive exploitation of energy resources had the largest impact on both the abiotic status (nutrient loads and concentrations in water) and the biotic indicators. In contrast, the predicted changes under the other two future worlds, consensus and fragmented, were more diverse and were mostly dictated by the projected climate. This work showed that the future scenarios, especially the mid-century ones, had significant impact on both abiotic status and biotic responses underpinning the need for implementing catchment management practices able to mitigate the ecological threat on waters in the long-term.

ACS Style

Konstantinos Stefanidis; Yiannis Panagopoulos; Maria Mimikou. Response of a multi-stressed Mediterranean river to future climate and socio-economic scenarios. Science of The Total Environment 2018, 627, 756 -769.

AMA Style

Konstantinos Stefanidis, Yiannis Panagopoulos, Maria Mimikou. Response of a multi-stressed Mediterranean river to future climate and socio-economic scenarios. Science of The Total Environment. 2018; 627 ():756-769.

Chicago/Turabian Style

Konstantinos Stefanidis; Yiannis Panagopoulos; Maria Mimikou. 2018. "Response of a multi-stressed Mediterranean river to future climate and socio-economic scenarios." Science of The Total Environment 627, no. : 756-769.

Journal article
Published: 19 March 2018 in International Journal of Environmental Research and Public Health
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During the last decades, Mediterranean freshwater ecosystems, especially lakes, have been under severe pressure due to increasing eutrophication and water quality deterioration. In this article, we compared the effectiveness of different data analysis methods by assessing the contribution of environmental parameters to eutrophication processes. For this purpose, principal components analysis (PCA), cluster analysis, and a self-organizing map (SOM) were applied, using water quality data from two transboundary lakes of North Greece. SOM is considered as an advanced and powerful data analysis tool because of its ability to represent complex and nonlinear relationships among multivariate data sets. The results of PCA and cluster analysis agreed with the SOM results, although the latter provided more information because of the visualization abilities regarding the parameters’ relationships. Besides nutrients that were found to be a key factor for controlling chlorophyll-a (Chl-a), water temperature was related positively with algal production, while the Secchi disk depth parameter was found to be highly important and negatively related toeutrophic conditions. In general, the SOM results were more specific and allowed direct associations between the water quality variables. Our work showed that SOMs can be used effectively in limnological studies to produce robust and interpretable results, aiding scientists and managers to cope with environmental problems such as eutrophication.

ACS Style

Ekaterini Hadjisolomou; Konstantinos Stefanidis; George Papatheodorou; Evanthia Papastergiadou. Assessment of the Eutrophication-Related Environmental Parameters in Two Mediterranean Lakes by Integrating Statistical Techniques and Self-Organizing Maps. International Journal of Environmental Research and Public Health 2018, 15, 547 .

AMA Style

Ekaterini Hadjisolomou, Konstantinos Stefanidis, George Papatheodorou, Evanthia Papastergiadou. Assessment of the Eutrophication-Related Environmental Parameters in Two Mediterranean Lakes by Integrating Statistical Techniques and Self-Organizing Maps. International Journal of Environmental Research and Public Health. 2018; 15 (3):547.

Chicago/Turabian Style

Ekaterini Hadjisolomou; Konstantinos Stefanidis; George Papatheodorou; Evanthia Papastergiadou. 2018. "Assessment of the Eutrophication-Related Environmental Parameters in Two Mediterranean Lakes by Integrating Statistical Techniques and Self-Organizing Maps." International Journal of Environmental Research and Public Health 15, no. 3: 547.

Journal article
Published: 19 April 2017 in Journal of Water Supply: Research and Technology-Aqua
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The Ali Efenti catchment is a rural upstream subcatchment of the Pinios river basin in central Greece. The average annual precipitation in this subcatchment is relatively higher and groundwater recharge is relatively faster than in the rest of the river basin. Yet, seasonal water shortages occur due to the rapid increase of water abstractions in the summer months, mainly for crop irrigation. Up until 2030 the gap between water supply and demand is expected to deteriorate, considering the impacts of climate and socio-economic change. The adoption of environmental restrictions on water abstraction, which is a measure foreseen in the local river basin management plan, could decrease water stress substantially from 19.2% to 13.9%. However, this would require enormous (−26%) cuts in the current water abstractions during June–September, lowering water demand coverage from 86% to 68%. Optimal combinations of measures, from an economic and environmental perspective, will need to be designed to bridge the gap between water supply and demand and restore water demand coverage to satisfactory levels. Hydrologic and water resources management modelling has been implemented using the Water Evaluation and Planning system (WEAP), which is a conceptual model based on water balances.

ACS Style

Alexandros Psomas; Yiannis Panagopoulos; Konstantinos Stefanidis; Maria Mimikou. Assessing future water supply and demand in a water-stressed catchment after environmental restrictions on abstractions. Journal of Water Supply: Research and Technology-Aqua 2017, jws2017130 .

AMA Style

Alexandros Psomas, Yiannis Panagopoulos, Konstantinos Stefanidis, Maria Mimikou. Assessing future water supply and demand in a water-stressed catchment after environmental restrictions on abstractions. Journal of Water Supply: Research and Technology-Aqua. 2017; ():jws2017130.

Chicago/Turabian Style

Alexandros Psomas; Yiannis Panagopoulos; Konstantinos Stefanidis; Maria Mimikou. 2017. "Assessing future water supply and demand in a water-stressed catchment after environmental restrictions on abstractions." Journal of Water Supply: Research and Technology-Aqua , no. : jws2017130.

Article
Published: 28 February 2017 in Aquatic Ecology
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Lentic ecosystems act as sentinels of climate change, and evidence exists that their sensitivity to warming varies along a latitudinal gradient. We assessed the effects of nutrient and water level variability on zooplankton community composition, taxonomic diversity and size structure in different climate zones by running a standardised controlled 6-months (May to November) experiment in six countries along a European north–south latitudinal temperature gradient. The mesocosms were established with two different depths and nutrient levels. We took monthly zooplankton samples during the study period and pooled a subsample from each sampling to obtain one composite sample per mesocosm. We found a significant effect of temperature on the community composition and size structure of the zooplankton, whereas no effects of water depth or nutrient availability could be traced. The normalised size spectrum became flatter with increasing temperature reflecting higher zooplankton size diversity due to higher abundance of calanoid copepods, but did not differ among depths or nutrient levels. Large-bodied cladocerans such as Daphnia decreased with temperature. Taxonomic diversity was positively related to size diversity, but neither of the two diversity measures demonstrated a clear pattern along the temperature gradient nor with nutrient and water levels. However, genus richness decreased at the warm side of the temperature gradient. Our experiment generally supports recent empirically based findings that a continuing temperature increase may result in lower genus richness and lower abundance of large-sized zooplankton grazers, the latter likely resulting in reduced control of phytoplankton.

ACS Style

Ülkü Nihan Tavşanoğlu; Michal Šorf; Konstantinos Stefanidis; Sandra Brucet; Semra Türkan; Helen Agasild; Didier L. Baho; Ulrike Scharfenberger; Josef Hejzlar; Eva Papastergiadou; Rita Adrian; David G. Angeler; Priit Zingel; Ayşe Idil Çakıroğlu; Arda Özen; Stina Drakare; Martin Søndergaard; Erik Jeppesen; Meryem Beklioğlu. Effects of nutrient and water level changes on the composition and size structure of zooplankton communities in shallow lakes under different climatic conditions: a pan-European mesocosm experiment. Aquatic Ecology 2017, 51, 257 -273.

AMA Style

Ülkü Nihan Tavşanoğlu, Michal Šorf, Konstantinos Stefanidis, Sandra Brucet, Semra Türkan, Helen Agasild, Didier L. Baho, Ulrike Scharfenberger, Josef Hejzlar, Eva Papastergiadou, Rita Adrian, David G. Angeler, Priit Zingel, Ayşe Idil Çakıroğlu, Arda Özen, Stina Drakare, Martin Søndergaard, Erik Jeppesen, Meryem Beklioğlu. Effects of nutrient and water level changes on the composition and size structure of zooplankton communities in shallow lakes under different climatic conditions: a pan-European mesocosm experiment. Aquatic Ecology. 2017; 51 (2):257-273.

Chicago/Turabian Style

Ülkü Nihan Tavşanoğlu; Michal Šorf; Konstantinos Stefanidis; Sandra Brucet; Semra Türkan; Helen Agasild; Didier L. Baho; Ulrike Scharfenberger; Josef Hejzlar; Eva Papastergiadou; Rita Adrian; David G. Angeler; Priit Zingel; Ayşe Idil Çakıroğlu; Arda Özen; Stina Drakare; Martin Søndergaard; Erik Jeppesen; Meryem Beklioğlu. 2017. "Effects of nutrient and water level changes on the composition and size structure of zooplankton communities in shallow lakes under different climatic conditions: a pan-European mesocosm experiment." Aquatic Ecology 51, no. 2: 257-273.

Journal article
Published: 12 January 2017 in Hydrobiologia
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K. Stefanidis; Eva Papastergiadou. Erratum to: Influence of hydrophyte abundance on the spatial distribution of zooplankton in selected lakes in Greece. Hydrobiologia 2017, 790, 311 -311.

AMA Style

K. Stefanidis, Eva Papastergiadou. Erratum to: Influence of hydrophyte abundance on the spatial distribution of zooplankton in selected lakes in Greece. Hydrobiologia. 2017; 790 (1):311-311.

Chicago/Turabian Style

K. Stefanidis; Eva Papastergiadou. 2017. "Erratum to: Influence of hydrophyte abundance on the spatial distribution of zooplankton in selected lakes in Greece." Hydrobiologia 790, no. 1: 311-311.