@article{Tompoulidou2024,

title = {A Geographic Object-Based Image Approach Based on the Sentinel-2 Multispectral Instrument for Lake Aquatic Vegetation Mapping: A Complementary Tool to In Situ Monitoring},

author = {Maria Tompoulidou and Elpida Karadimou and Antonis Apostolakis and Vasiliki Tsiaoussi},

doi = {10.3390/rs16050916},

issn = {2072-4292},

year  = {2024},

date = {2024-03-05},

urldate = {2024-03-05},

journal = {Remote Sensing},

volume = {16},

number = {5},

publisher = {MDPI AG},

abstract = {Aquatic vegetation is an essential component of lake ecosystems, used as a biological indicator for in situ monitoring within the Water Framework Directive. We developed a hierarchical object-based image classification model with multi-seasonal Sentinel-2 imagery and suitable spectral indices in order to map the aquatic vegetation in a Mediterranean oligotrophic/mesotrophic deep lake; we then applied the model to another lake with similar abiotic and biotic characteristics. Field data from a survey of aquatic macrophytes, undertaken on the same dates as EO data, were used within the accuracy assessment. The aquatic vegetation was discerned into three classes: emergent, floating, and submerged aquatic vegetation. Geographic object-based image analysis (GEOBIA) proved to be effective in discriminating the three classes in both study areas. Results showed high effectiveness of the classification model in terms of overall accuracy, particularly for the emergent and floating classes. In the case of submerged aquatic vegetation, challenges in their classification prompted us to establish specific criteria for their accurate detection. Overall results showed that GEOBIA based on spectral indices was suitable for mapping aquatic vegetation in oligotrophic/mesotrophic deep lakes. EO data can contribute to large-scale coverage and high-frequency monitoring requirements, being a complementary tool to in situ monitoring.},

keywords = {General Earth and Planetary Sciences},

pubstate = {published},

tppubtype = {article}

}

@article{Doulgeris2024,

title = {Assessment of Environmentally Minimum Water Level in a Mediterranean Lake Using Morphological, Hydrological and Biological Factors},

author = {Charalampos Doulgeris and Chrysoula Ntislidou and Olga Petriki and Dimitrios Zervas and Rafaela Nikolaidou and Dimitra C. Bobori},

doi = {10.3390/su16020933},

issn = {2071-1050},

year  = {2024},

date = {2024-01-22},

urldate = {2024-01-22},

journal = {Sustainability},

volume = {16},

number = {2},

publisher = {MDPI AG},

abstract = {Water resources management requires comprehensive and integrated approaches that jointly consider hydrological, ecological and social factors. The assessment of lakes’ environmentally minimum water level is a critical tool for the sustainable management and protection of their ecosystems. This work combines the morphological, hydrological and biological factors of a Mediterranean lake (Lake Volvi, northern Greece) to assess its environmentally minimum water level. Initially, the morphological characteristics of the lake’s bottom were analyzed, with consideration given to the protection of the lake’s ecosystem and to the need to meet the water requirements for economic activities. Then, a hydromorphological analysis was conducted, relying on the surface water inflows to the lake from its hydrological catchment and the lake’s water level -volume relationship. In addition, the water level requirements of the biological communities of macrophytes, benthic macroinvertebrates, and fish, as revealed after samplings were taken from the lake’s littoral zone, are considered. Based on the above methodologies, the environmentally minimum water level of Lake Volvi is proposed to be lowered by as much as 35.8 m from February to May and 35.3 m from June to January in order to maintain the ecological integrity of the lake and the sustainable use of its water resources. The present study establishes a foundation for informed water resource management; however, ongoing research can improve methodologies and address emerging questions, fostering advancements in sustainable water management practices.},

keywords = {Building and Construction, Geography, Management, Monitoring, Planning and Development, Policy and Law, Renewable Energy, Sustainability and the Environment},

pubstate = {published},

tppubtype = {article}

}

@article{Mavromati2023,

title = {Does littoral substrate affect macroinvertebrate assemblages in Mediterranean lakes?},

author = {Efpraxia Mavromati and Dimitra Kemitzoglou and Vasiliki Tsiaoussi},

doi = {10.1007/s10452-023-10037-7},

issn = {1573-5125},

year  = {2023},

date = {2023-06-05},

journal = {Aquat Ecol},

volume = {57},

number = {3},

pages = {667--679},

publisher = {Springer Science and Business Media LLC},

abstract = {The objective of this study was to investigate the effects of substrate type in macroinvertebrate assemblages in Mediterranean lakes. Samplings have taken place in the littoral zone of 21 lakes in Greece, between 2015 and 2018. We compared benthic macroinvertebrate assemblages among three substrate types of their littoral zones; sandy, covered with macrophytes and stony substrate. Benthic macroinvertebrate assemblages at sites with extended macrophyte cover differed only slightly in composition and abundance from the ones found in stony and sandy substrates. Coenagrionidae were indicative of sites covered with macrophytes and Oligochaeta and Erpobdellidae were representative of stony substrates. The type of substrate proved to be a statistically significant factor influencing the number of benthic macroinvertebrate taxa, the relative abundance of Oligochaeta and the relative abundance of Odonata. In the context of designing site-adapted management measures, priority could be given to the conservation and restoration of aquatic vegetation in lake littoral zones, which host rich macroinvertebrate assemblages with abundant taxa of Odonata.},

keywords = {Aquatic Science, Behavior and Systematics, Ecology, Evolution},

pubstate = {published},

tppubtype = {article}

}

@article{Kelly2023,

title = {Development of novel diatom metrics to assess ecological status of phytobenthos in Greek lakes},

author = {Martyn Kelly and Steve Juggins and Kimon Moschandreou and Dimitra Kemitzoglou and Vasiliki Tsiaoussi},

doi = {10.1016/j.ecolind.2023.109974},

issn = {1470-160X},

year  = {2023},

date = {2023-02-16},

journal = {Ecological Indicators},

volume = {147},

publisher = {Elsevier BV},

abstract = {Mediterranean lakes present particular challenges when developing ecological assessment techniques, due partly to long histories of human activity in their catchments but also to strong interactions with climate, intensifying in recent decades due to global warming. A survey of diatoms in lakes in Greece revealed both a strong nutrient gradient and a salinity gradient. It is necessary to disentangle these when assessing ecological status in order that appropriate measures for restoring good ecological status are applied. Two approaches were used to develop a Water Framework Directive-compatible metric for assessing ecological status using diatoms. The strongest relationship was obtained using weighted averaging, but an alternative metric, generated by rescaling a well-established and widely used diatom metric performed only slightly less well. The limited number of lakes in Greece resulted in a small dataset, creating a risk of overfitting models and the rescaled metric has the advantage of drawing on a broader autecological knowledge base. Supplementary metrics to evaluate salinity are also proposed in order to ensure that lakes subject to this pressure are clearly differentiated from those where nutrient impacts predominate. Approaches to defining reference conditions and status class boundaries draw on established criteria developed for Water Framework Assessments in Europe to ensure that status assessments in Greece reflect similar levels of ambition to those established elsewhere in the European Union.},

keywords = {Behavior and Systematics, Ecology, Evolution, General Decision Sciences},

pubstate = {published},

tppubtype = {article}

}

@article{Papadimos2022,

title = {Assessing Lake Response to Extreme Climate Change Using the Coupled MIKE SHE/MIKE 11 Model: Case Study of Lake Zazari in Greece},

author = {Dimitris Papadimos and Kleoniki Demertzi and Dimitris Papamichail},

doi = {10.3390/w14060921},

issn = {2073-4441},

year  = {2022},

date = {2022-03-15},

journal = {Water},

volume = {14},

number = {6},

publisher = {MDPI AG},

abstract = {Lakes, either artificial or natural, are greatly important as a component in their catchments’ hydrology, but also as ecosystem service providers. However, due to climate change, they have begun to face numerous problems with their water quality and quantity. Furthermore, general circulation models (GCMs) show future climate change with a reduction in rainfall and increase in temperature. The aim of the current study is to present an application where GCMs and state-of-the-art hydrological modelling system MIKE SHE/MIKE 11 are combined for assessing the response of a Greek lake in terms of its water balance and water level under climate change. Four general circulation models (GCMs; GFDL-CM3, MIROC-ESM-CHEM, MIROC-ESM, IPSL-CM5A-LR) for the extreme climate change scenario of RCP8.5 were used in the basin of Lake Zazari in Greece as a case study. Results showed that, by keeping the irrigated demands (the main water user) unchanged in the future, the lake exhibited a lower water level for all GCMs, fluctuating from −0.70 to −1.8 m for the mean (min) water level and from −0.30 to −1.20 m for the mean (max) water level. Instead of the above and by preserving the amount of withdraw water n from the lake at a certain percentage of inflows, the irrigated area should be reduced from 54.1% to 64.05% depending on the circulation model.},

keywords = {Aquatic Science, Biochemistry, Geography, Planning and Development, Water Science and Technology},

pubstate = {published},

tppubtype = {article}

}

@article{Markogianni2022,

title = {Modelling of Greek Lakes Water Quality Using Earth Observation in the Framework of the Water Framework Directive (WFD)},

author = {Vassiliki Markogianni and Dionissios Kalivas and George P. Petropoulos and Elias Dimitriou},

doi = {10.3390/rs14030739},

issn = {2072-4292},

year  = {2022},

date = {2022-02-04},

journal = {Remote Sensing},

volume = {14},

number = {3},

publisher = {MDPI AG},

abstract = {Given the great importance of lakes in Earth’s environment and human life, continuous water quality (WQ) monitoring within the frame of the Water Framework Directive (WFD) is the most crucial aspect for lake management. In this study, Earth Observation (EO) data from Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Landsat 8 Operational Land Imager (OLI) sensors have been combined with co-orbital in situ measurements from 50 lakes located in Greece with the main objective of delivering robust WQ assessment models. Correlation analysis among in situ co-orbital WQ data (Chlorophylla, Secchi depths, Total phosphorus-TP-) contributed to distinguishing their inter-relationships and improving the WQ models’ accuracy. Subsequently, stepwise multiple regression analysis (MLR) of the available TP and Secchi depth datasets was implemented to explore the potential to establish optimal quantitative models regardless of lake characteristics. Then, further MLR analysis concerning whether the lakes are natural or artificial was conducted with the basic aim of generating different remote sensing derived models for different types of lakes, while their combination was further utilized to assess their trophic status. Correlation matrix results showed a high and positive relationship between TP and Chlorophyll-a (0.85), whereas high negative relationships were found between Secchi depth with TP (−0.84) and Chlorophyll-a (−0.83). MLRs among Landsat data and Secchi depths resulted in 3 optimal models concerning the assessment of Secchi depth of all lakes (Secchigeneral; R = 0.78; RMSE = 0.24 m), natural (Secchinatural; R = 0.95; RMSE = 0.14 m) and artificial (Secchiartificial; R = 0.62; RMSE = 0.1 m), with reliable accuracy. Study findings showed that TP-related MLR analyses failed to deliver a statistically acceptable model for the reservoirs; nevertheless, they delivered a robust TPgeneral (R = 0.71; RMSE = 1.41 mg/L) and TPnatural model (R = 0.93; RMSE = 1.43 mg/L). Subsequently, trophic status classification was conducted herein, calculating Carlson’s Trophic State Index (TSI) initially throughout all lakes and then oriented toward natural-only and artificial-only lakes. Those three types of TSI (general, natural, artificial) were calculated based on previously published satellite-derived Chlorophyll-a (Chl-a) assessment models and the hereby specially designed WQ models (Secchi depth, TP). The higher deviation of satellite-derived TSI values in relation to in situ ones was detected in reservoirs and shallower lakes (mean depth < 5 m), indicating noticeable divergences among natural and artificial lakes. All in all, the study findings provide important support toward the perpetual WQ monitoring and trophic status prediction of Greek lakes and, by extension, their sustainable management, particularly in cases when ground truth data is limited.},

keywords = {General Earth and Planetary Sciences},

pubstate = {published},

tppubtype = {article}

}

@article{Mavromati2021,

title = {A new WFD—compliant littoral macroinvertebrate index for monitoring and assessment of Mediterranean lakes (HeLLBI)},

author = {Efpraxia Mavromati and Dimitra Kemitzoglou and Vasiliki Tsiaoussi and Maria Lazaridou},

doi = {10.1007/s10661-021-09493-1},

issn = {1573-2959},

year  = {2021},

date = {2021-10-23},

journal = {Environ Monit Assess},

volume = {193},

number = {11},

publisher = {Springer Science and Business Media LLC},

abstract = {A new multimetric index (HeLLBI) based on littoral benthic macroinvertebrates is presented in this paper for classification of Greek natural lakes, in compliance with the requirements of Water Framework Directive (WFD). The method was developed based on the collection of littoral benthic invertebrate fauna and environmental data from 109 sampling sites in 21 natural lakes of the Greek National Water Monitoring Network. We focused the analysis on the effects of shore morphological alterations and eutrophication to the littoral invertebrate fauna, identified to family level, except oligochaetes, which were identified as a class, and more particularly to taxonomic composition and abundance, to taxa sensitivity, and to richness/diversity. Three metrics were included in the multimeric index: the relative abundance of Odonata classes, the Average Score per Taxon, and the Simpson’s diversity index. The metrics were converted to ecological quality ratios and ecological class boundaries were defined. The final multimetric index HeLLBI is expressed as an arithmetic average of normalized ecological quality ratios of the above metrics and a final score was assigned to each lake. Pressure-response relationships of HeLLBI scores were statistically tested for morphological alterations, expressed as percentage of artificial shoreline, and eutrophication, expressed as total phosphorus. The HeLLBI scores correspond to ecological classes, according to WFD, and sampling sites with different ecological status contained distinct biological communities; those at high status where more diverse and with sensitive taxa and as the water quality deteriorated, macroinvertebrate assemblages consisted of fewer and more tolerant to degradation taxa. The HeLLBI method gave a reliable assessment of littoral benthic invertebrate fauna of Greek natural lakes and could be a useful tool for the classification of ecological status of other Mediterranean lakes.},

keywords = {General Environmental Science, General Medicine, Management, Monitoring, Policy and Law, Pollution},

pubstate = {published},

tppubtype = {article}

}

@article{Zervas2021,

title = {Multiple-Facet Diversity Patterns of Aquatic Vegetation in Lakes along a Trophic Gradient},

author = {Dimitrios Zervas and Vasiliki Tsiaoussi and Athanasios S. Kallimanis and Panayotis Dimopoulos and Erwin Bergmeier and Ioannis Tsiripidis},

doi = {10.3390/w13162281},

issn = {2073-4441},

year  = {2021},

date = {2021-08-20},

journal = {Water},

volume = {13},

number = {16},

publisher = {MDPI AG},

abstract = {The EU Water Framework Directive foresees the ecological assessment of surface waters against identified pressures. Nutrient loading is the main pressure impairing the ecological quality of lake ecosystems, and aquatic macrophytes are considered good indicators of ecological response. In this study, we statistically assessed different aspects of aquatic plant (macrophyte) diversity in response to different trophic levels in Mediterranean lakes. We used 5690 relevés of aquatic vegetation, distributed over 305 transects, sampled in 18 freshwater lake ecosystems during 2013–2016. Our results show a significant decrease in taxonomic alpha diversity in lakes with a total phosphorus content above 100 μg/L. Syntaxonomic diversity followed the species richness pattern as well. Functional richness decreased along the trophic gradient, while functional dispersion was higher in lakes with high trophic levels. Taxonomic and functional beta partitioning presented changes in assembly processes leading to greater community homogeneity in lakes with higher trophic levels. In summary, we found no redundancy between taxonomic and functional diversity indices. These results provide novel insights into aquatic plant assembly processes of impacted freshwater lakes needed to forward conservation and restoration practices.},

keywords = {Aquatic Science, Biochemistry, Geography, Planning and Development, Water Science and Technology},

pubstate = {published},

tppubtype = {article}

}

@article{Latinopoulos2021,

title = {“One Out–All Out” Principle in the Water Framework Directive 2000—A New Approach with Fuzzy Method on an Example of Greek Lakes},

author = {Dionissis Latinopoulos and Mike Spiliotis and Chrysoula Ntislidou and Ifigenia Kagalou and Dimitra Bobori and Vasiliki Tsiaoussi and Maria Lazaridou},

doi = {10.3390/w13131776},

issn = {2073-4441},

year  = {2021},

date = {2021-06-27},

journal = {Water},

volume = {13},

number = {13},

publisher = {MDPI AG},

abstract = {The “One Out–All Out” (OOAO) principle imposed by the WFD selects the worst ecological status assessed by different biological quality elements (BQEs). Since it is a precautionary rule that can lead to problems of underestimation of the overall status, its amendment has been a matter of debate for WFD 20+. The use of fuzzy methods that express the functional relationships between variables in ecology and management has been gaining more ground recently. Here is attempted the inclusion of a fuzzy regression among the frequently monitored BQE (phytoplankton) and the outcome of OOAO application in six Greek lakes. The latter was determined by the comparison of four BQE indices in order to assess the extent to which BQEs might underpin the optimal/actual qualitative classification of a waterbody. This approach encompasses the uncertainty and the possibility to broaden the acceptable final EQR based on the character and status of each lake. We concluded that the fuzzy OOAO is an approach that seems to allow a better understanding of the WFD implementation and case-specific evaluation, including the uncertainty in classification as an asset. Moreover, it offers a deeper understanding through self-learning processes based on the existing datasets.},

keywords = {Aquatic Science, Biochemistry, Geography, Planning and Development, Water Science and Technology},

pubstate = {published},

tppubtype = {article}

}

@article{Zervou2021,

title = {Cyanobacterial Toxins and Peptides in Lake Vegoritis, Greece},

author = {Sevasti-Kiriaki Zervou and Kimon Moschandreou and Aikaterina Paraskevopoulou and Christophoros Christophoridis and Elpida Grigoriadou and Triantafyllos Kaloudis and Theodoros M. Triantis and Vasiliki Tsiaoussi and Anastasia Hiskia},

doi = {10.3390/toxins13060394},

issn = {2072-6651},

year  = {2021},

date = {2021-06-01},

journal = {Toxins},

volume = {13},

number = {6},

publisher = {MDPI AG},

abstract = {Cyanotoxins (CTs) produced by cyanobacteria in surface freshwater are a major threat for public health and aquatic ecosystems. Cyanobacteria can also produce a wide variety of other understudied bioactive metabolites such as oligopeptides microginins (MGs), aeruginosins (AERs), aeruginosamides (AEGs) and anabaenopeptins (APs). This study reports on the co-occurrence of CTs and cyanopeptides (CPs) in Lake Vegoritis, Greece and presents their variant-specific profiles obtained during 3-years of monitoring (2018–2020). Fifteen CTs (cylindrospermopsin (CYN), anatoxin (ATX), nodularin (NOD), and 12 microcystins (MCs)) and ten CPs (3 APs, 4 MGs, 2 AERs and aeruginosamide (AEG A)) were targeted using an extended and validated LC-MS/MS protocol for the simultaneous determination of multi-class CTs and CPs. Results showed the presence of MCs (MC-LR, MC-RR, MC-YR, dmMC-LR, dmMC-RR, MC-HtyR, and MC-HilR) and CYN at concentrations of <1 μg/L, with MC-LR (79%) and CYN (71%) being the most frequently occurring. Anabaenopeptins B (AP B) and F (AP F) were detected in almost all samples and microginin T1 (MG T1) was the most abundant CP, reaching 47.0 μg/L. This is the first report of the co-occurrence of CTs and CPs in Lake Vegoritis, which is used for irrigation, fishing and recreational activities. The findings support the need for further investigations of the occurrence of CTs and the less studied cyanobacterial metabolites in lakes, to promote risk assessment with relevance to human exposure.},

keywords = {Health, Toxicology, Toxicology and Mutagenesis},

pubstate = {published},

tppubtype = {article}

}

@article{Kagalou2021,

title = {Setting the Phosphorus Boundaries for Greek Natural Shallow and Deep Lakes for Water Framework Directive Compliance},

author = {Ifigenia Kagalou and Chrysoula Ntislidou and Dionissis Latinopoulos and Dimitra Kemitzoglou and Vasiliki Tsiaoussi and Dimitra Bobori},

doi = {10.3390/w13050739},

issn = {2073-4441},

year  = {2021},

date = {2021-03-09},

journal = {Water},

volume = {13},

number = {5},

publisher = {MDPI AG},

abstract = {Eutrophication caused by nutrient enrichment is a predominant stressor leading to lake degradation and, thus, the set-up of boundaries that support good ecological status, the Water Framework Directive’s main target, is a necessity. Greece is one of the Member States that have recorded delays in complying with the coherent management goals of European legislation. A wide range of different statistical approaches has been proposed in the Best Practice Guide for determining appropriate nutrient thresholds. To determine the nutrient thresholds supporting the good status of natural Greek lakes, the phytoplankton dataset gathered from the national monitoring programme (2015–2020) was used for shallow and deep natural lakes. The regression analyses were sufficient and robust in order to derive total phosphorus thresholds that ranged from 20 to 41 μg/L in shallow and 15–32 μg/L in deep natural lake types. Nutrient boundaries that encompass the stressors these lakes are subject to, are essential in proper lake management design.},

keywords = {Aquatic Science, Biochemistry, Geography, Planning and Development, Water Science and Technology},

pubstate = {published},

tppubtype = {article}

}

@article{Doulgeris2020,

title = {Assessment of Minimum Water Level in Lakes and Reservoirs Based on Their Morphological and Hydrological Features},

author = {Charalampos Doulgeris and Panagiota Koukouli and Pantazis Georgiou and Paschalis Dalampakis and Dimitrios Karpouzos},

doi = {10.3390/hydrology7040083},

issn = {2306-5338},

year  = {2020},

date = {2020-11-06},

journal = {Hydrology},

volume = {7},

number = {4},

publisher = {MDPI AG},

abstract = {The sustainable management of lakes and reservoirs requires the determination of their minimum environmental water level. Even though the assessment of minimum water level depends on a number of biotic and abiotic factors of the lake ecosystem, in many cases these factors are not entirely known and, furthermore, their evaluation is usually a challenging and laborious task. On the other hand, the lakes/reservoirs may comprise an important water resource to meet the requirements arising from economic activities. In this paper, the morphological and hydrological features of four lakes of northern Greece were analysed in order to assess their minimum environmental water level. The hydromorphological analysis was based on the relationship of the lake surface area and volume with water level as well as the water inflow from the lake’s hydrological catchment area, considering as the lake’s critical volume storage, the annual water volume flowing into a lake from its hydrological catchment area with a probability of exceedance 50% of a long time series of hydrological years. By combining morphological and hydrological features, the proposed methodology aimed to extend the analysis based solely on morphological features, and assess more comprehensively the minimum environmental water level in the four lakes, ensuring also the rising from the minimum level to the maximum (overflow) level for most of the hydrological years.},

keywords = {Earth-Surface Processes, Oceanography, Waste Management and Disposal, Water Science and Technology},

pubstate = {published},

tppubtype = {article}

}

@article{Petriki2020,

title = {Assessing the Ecological Water Level: The Case of Four Mediterranean Lakes},

author = {Olga Petriki and Dimitrios Zervas and Charalampos Doulgeris and Dimitra Bobori},

doi = {10.3390/w12112977},

issn = {2073-4441},

year  = {2020},

date = {2020-10-23},

journal = {Water},

volume = {12},

number = {11},

publisher = {MDPI AG},

abstract = {The ecological water regime in lake water bodies refers to the water levels that enable the fulfillment of the ecosystem’s multiple functions. Therefore, assessing the ecological water regime necessitates the consideration of hydrological, economic, social, and ecological factors. The present research is focused on the assessment of the ecological water level of four Mediterranean natural lake ecosystems, considering their morphological and biological features. Initially, suggestions on the ecological water regime of the studied lakes were made based on an analysis of the lakes’ morphometry. Further, the ecological and biological requirements of the present fish fauna and aquatic macrophytic vegetation were considered. For the latter, mapping was conducted by extensive sampling according to international standards, in order to assess macrophyte composition, abundance, and chorology, as well as species sensitivity to water level fluctuations. The above guided the proposals on the optimal water level regime that should be met by each lake regarding the macrophytic and fish communities’ sustainability, also taking into account the unique hydromorphological features of each lake. The differences in the outcoming results revealed that hydromorphological and biological approaches should be combined for assessing lakes’ ecological water regimes.},

keywords = {Aquatic Science, Biochemistry, Geography, Planning and Development, Water Science and Technology},

pubstate = {published},

tppubtype = {article}

}

@article{Markogianni2020,

title = {Estimating Chlorophyll-a of Inland Water Bodies in Greece Based on Landsat Data},

author = {Vassiliki Markogianni and Dionissios Kalivas and George P. Petropoulos and Elias Dimitriou},

doi = {10.3390/rs12132087},

issn = {2072-4292},

year  = {2020},

date = {2020-06-29},

journal = {Remote Sensing},

volume = {12},

number = {13},

publisher = {MDPI AG},

abstract = {Assessing chlorophyll-a (Chl-a) pigments in complex inland water systems is of key importance as this parameter constitutes a major ecosystem integrity indicator. In this study, a methodological framework is proposed for quantifying Chl-a pigments using Earth observation (EO) data from Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and 8 Operational Land Imager (OLI) sensors. The first step of the methodology involves the implementation of stepwise multiple regression (MLR) analysis of the available Chl-a dataset. Then, principal component analysis (PCA) is performed to explore Greek lakes’ potential interrelationships based on their Chl-a values in conjunction with certain criteria: their characteristics (artificial/natural), typology, and climatic type. Additionally, parameters such as seasonal water sampling and the date difference between sampling and satellite overpass are taken into consideration. Next, is implemented a stepwise multiple regression analysis among different groups of cases, formed by the criteria indicated from the PCA itself. This effort aimed at exploring different remote sensing-derived Chl-a algorithms for various types of lakes. The practical use of the proposed approach was evaluated in a total of 50 lake water bodies (natural and artificial) from 2013–2018, constituting the National Lake Network Monitoring of Greece in the context of the Water Framework Directive (WFD). All in all, the results evidenced the suitability of Landsat data when used with the proposed technique to estimate log-transformed Chl-a. The proposed scheme resulted in the development of models separately for natural (R = 0.78; RMSE = 1.3 μg/L) and artificial lakes (R = 0.76; RMSE = 1.29 μg/L), while the model developed without criteria proved weaker (R = 0.65; RMSE = 1.85 μg/L) in comparison to the other ones examined. The methodological framework proposed herein can be used as a useful resource toward a continuous monitoring and assessment of lake water quality, supporting sustainable water resources management.},

keywords = {General Earth and Planetary Sciences},

pubstate = {published},

tppubtype = {article}

}

@article{Zervas2020,

title = {A phytosociological survey of aquatic vegetation in the main freshwater lakes of Greece},

author = {Dimitrios Zervas and Ioannis Tsiripidis and Erwin Bergmeier and Vasiliki Tsiaoussi},

doi = {10.3897/vcs/2020/48377},

issn = {2683-0671},

year  = {2020},

date = {2020-05-04},

urldate = {2020-05-04},

journal = {VCS},

volume = {1},

pages = {53--75},

publisher = {Pensoft Publishers},

abstract = {Aims: This study aims to contribute to the knowledge of European freshwater lake ecosystems with updated and new information on aquatic plant communities, by conducting national-scale phytosociological research of freshwater lake vegetation in Greece. Moreover, it investigates the relationship between aquatic plant communities and lake environmental parameters, including eutrophication levels and hydro-morphological conditions. Study area: Lakes in Greece, SE Europe. Methods: 5,690 phytosociological relevés of aquatic vegetation were sampled in 18 freshwater lake ecosystems during 2013–2016. The relevés were subjected to hierarchical cluster and indicator species analyses in order to identify associations and communities of aquatic vegetation, as well as to describe their syntaxonomy. Multiple regression analysis was applied to investigate the relationship between vegetation syntaxa and environmental parameters of lakes, i.e. physico-chemical parameters and water level fluctuation. Results: Ninety-nine plant taxa belonging to 30 different families were recorded. Forty-six vegetation types were identified and described by their ecological characteristics, diagnostic taxa and syntaxonomical status. Thirteen vegetation types, the largest number belonging to the vegetation class Charetea, are considered to be new records for Greece. The distribution of the vegetation types recorded in the 18 freshwater lakes was found to depend on environmental parameters and levels of eutrophication. Conclusions: An updated aquatic vegetation inventory was produced for Greek lakes, and primary results showed that the presence/absence of aquatic plant communities and the community composition in freshwater lakes can be utilized to assess the pressure of eutrophication on lake ecosystems. Taxonomic reference: Euro+Med (2006–). Abbreviations: MNT = Mean number of taxa; WFD = Water Framework Directive.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Zervas2019,

title = {Exploring the relationships between aquatic macrophyte functional traits and anthropogenic pressures in freshwater lakes},

author = {Dimitrios Zervas and Vasiliki Tsiaoussi and Athanasios S. Kallimanis and Panayotis Dimopoulos and Ioannis Tsiripidis},

doi = {10.1016/j.actao.2019.103443},

issn = {1146-609X},

year  = {2019},

date = {2019-06-27},

journal = {Acta Oecologica},

volume = {99},

publisher = {Elsevier BV},

abstract = {Modern water resource management requires biomonitoring of the structure and functioning of freshwater ecosystems, which may be better illuminated by functional trait distribution patterns and responses across human-induced pressure gradients. In this study, we applied the RLQ, the fourth-corner and their novel combination methods, in order to assess the relationship between the distribution of 30 aquatic macrophyte functional traits and 14 indicators of anthropogenic pressures across 16 freshwater lakes. Our findings showed that there is a statistically significant relationship between the distribution of specific functional traits and anthropogenic pressures. Eutrophication was the dominant pressure and the shift from a submerged-macrophyte dominated vegetation community to an emergent one was the most important functional response. Aerial reproduction and dispersal traits were found to replace water-related ones under higher nutrient concentrations. Trophic and light preferences of macrophytic species increased, while their leaf morphology was found to change from tubular/capillary leaf types with low leaf area values to entire leaf types with greater leaf area. These results provide hints on the changes in ecosystem functioning occurring as a response to human-induced drivers. Therefore, this assessment approach could provide important support to the tasks of biomonitoring, conservation and management planning in freshwater ecosystems.},

keywords = {Behavior and Systematics, Ecology, Evolution, Nature and Landscape Conservation},

pubstate = {published},

tppubtype = {article}

}

@article{Mavromati2018,

title = {Relationships Among Land Use Patterns, Hydromorphological Features and Physicochemical Parameters of Surface Waters: WFD Lake Monitoring in Greece},

author = {Efpraxia Mavromati and Ifigenia Kagalou and Dimitra Kemitzoglou and Antonis Apostolakis and Miltiadis Seferlis and Vasiliki Tsiaoussi},

doi = {10.1007/s40710-018-0315-6},

issn = {2198-7505},

year  = {2018},

date = {2018-06-22},

journal = {Environ.  Process.},

volume = {5},

number = {S1},

pages = {139--151},

publisher = {Springer Science and Business Media LLC},

abstract = {The national monitoring network of waters in Greece, in the context of Water Framework Directive (WFD), comprises 50 lake water bodies, both natural and artificial. The aims of the study are: (i) to present the pressures resulting from land cover and population density at river basin level; and (ii) to link catchment area features with physicochemical results from the first period of WFD monitoring. Land cover, population data in the catchment and physicochemical parameters were the main variables used in order to assess the lakes of the Greek WFD monitoring network. Intensive agriculture and urbanization, described as population density, proved to be the main pressure of severe impacted lakes as they were both highly associated with total phosphorus. Principal Components Analysis was used to position the Greek lakes along physical and chemical attributes, such as secchi depth, total phosphorus and ion concentrations and separate them according to their water quality. Clear reservoirs and natural lakes with high secchi depth were separated from more impacted ones with low secchi depth revealing a gradient of eutrophication, the most crucial anthropogenic pressure in Greece and in the Mediterranean area. The sustainable management of Greek lakes requires mitigation measures at a catchment scale, in order to regulate land uses, as well as site specific measures when needed.},

keywords = {Environmental Engineering, Health, Management, Monitoring, Policy and Law, Pollution, Toxicology and Mutagenesis, Water Science and Technology},

pubstate = {published},

tppubtype = {article}

}

@article{Ntislidou2018,

title = {A new multimetric macroinvertebrate index for the ecological assessment of Mediterranean lakes},

author = {Chrysoula Ntislidou and Maria Lazaridou and Vasiliki Tsiaoussi and Dimitra Bobori},

doi = {10.1016/j.ecolind.2018.05.071},

issn = {1470-160X},

year  = {2018},

date = {2018-06-20},

journal = {Ecological Indicators},

volume = {93},

pages = {1020--1033},

publisher = {Elsevier BV},

abstract = {This study outlines the development and application of a new multimetric index (Greek Lake Benthic macroinvertebrate Index – GLBiI) for the assessment of the ecological quality of Greek lakes, based on the ecological quality ratio (EQR), under the requirements of the Water Framework Directive. Profundal and sublittoral benthic macroinvertebrates from 18 lakes were biannually sampled across Greece. Additionally, 21 environmental parameters and 5 human pressures were assessed for each lake. The hindcasting approach was used for the establishment of reference conditions after minimizing human pressures. A pool of 84 candidate metrics, representing diversity/richness, sensitivity, functional traits, and taxonomical composition, were tested for the development of the multimetric index. Spearman’s rank correlation extracted seven environmental parameters (lake area, mean depth, altitude, alkalinity, dissolved oxygen at bottom and conductivity at bottom) and three human pressures (total phosphorus, population density and non-natural land cover) that were further stepwise linear regressed against each biological metric for pressure-response relationships. Finally, three metrics, the number of taxa and the Simpson's diversity index in the profundal and sublittoral zones, and the relative contribution of Chironomidae (%) family in the profundal zone, were selected as the most appropriate, responding to eutrophication (expressed as total phosphorus and non-natural land cover). The multimetric index GLBiI was expressed as the mean of the EQRs of its metrics following a five class ecological status system. This assessment method may be used in other Mediterranean lakes with similar characteristics.},

keywords = {Behavior and Systematics, Ecology, Evolution, General Decision Sciences},

pubstate = {published},

tppubtype = {article}

}

@article{Zervas2018,

title = {HeLM: a macrophyte-based method for monitoring and assessment of Greek lakes},

author = {Dimitrios Zervas and Vasiliki Tsiaoussi and Ioannis Tsiripidis},

doi = {10.1007/s10661-018-6708-1},

issn = {1573-2959},

year  = {2018},

date = {2018-01-05},

journal = {Environ Monit Assess},

volume = {190},

number = {6},

publisher = {Springer Science and Business Media LLC},

abstract = {The Water Framework Directive (WFD) requires Member States to develop appropriate assessment methods for the classification of the ecological status of their surface waters. Mediterranean region has lagged behind in this task, so we propose here the first developed method for Greek lakes, Hellenic Lake Macrophyte (HeLM) assessment method. This method is based on two metrics, a modified trophic index and maximum colonization depth Cmax that quantify the degree of changes in lake macrophytic vegetation, as a response to eutrophication and general degradation pressures. The method was developed on the basis of a data set sampled from 272 monitoring transects in 16 Greek lakes. Sites from three lakes were selected as potential reference sites by using a screening process. Ecological quality ratios were calculated for each metric and for each lake, and ecological status class boundaries were defined. For the evaluation of effectiveness of the method, the correlations between individual metrics and final HeLM values and common pressure indicators, such as total phosphorus, chlorophyll a and Secchi depth, were tested and found highly significant and relatively strong. In addition, the ability of HeLM values and its individual metrics to distinguish between different macrophytic communities’ structure was checked using aquatic plant life-forms and found satisfactory. The HeLM method gave a reliable assessment of the macrophytic vegetation’s condition in Greek lakes and may constitute a useful tool for the classification of ecological status of other Mediterranean lakes.},

keywords = {General Environmental Science, General Medicine, Management, Monitoring, Policy and Law, Pollution},

pubstate = {published},

tppubtype = {article}

}

@article{Petriki2017,

title = {A fish-based index for the assessment of the ecological quality of temperate lakes},

author = {Olga Petriki and Maria Lazaridou and Dimitra Bobori},

doi = {10.1016/j.ecolind.2017.03.029},

issn = {1470-160X},

year  = {2017},

date = {2017-04-08},

journal = {Ecological Indicators},

volume = {78},

pages = {556--565},

publisher = {Elsevier BV},

abstract = {A fish – based index for the assessment of the ecological quality of natural temperate lakes was developed, in accordance to the requirements of the Water Framework Directive (WFD) 2000/60/EC. As a case study, 11 natural lakes located at northern and western Greece were selected. Fish surveys were conducted during mid summer to mid autumn in 2010, 2011 and 2012 using Nordic gillnets and electrofishing. Environmental parameters and anthropogenic pressures were assessed for each lake. Fish species richness, abundance, trophic, reproductive and habitat functional guilds were used for extracting a set of 107 metrics, meeting the requirements of the WFD. All metrics were initially tested as candidates for the index development. A stepwise linear regression of each metric against environmental parameters (lake area, altitude, maximum depth, alkalinity) and anthropogenic pressures (drainage area covered by non-natural land uses – NNLC, water total phosphorus concentrations – TP, Lake Habitat Modification Score – LHMS) was initially conducted for ensuring pressure-response relationships. Reference conditions for each lake were estimated by the hindcasting procedure and the ecological quality for each lake was expressed as the ecological quality ratio (EQR) by a value ranging from 0 (poor quality) to 1 (excellent quality). Two fish fauna metrics, the relative numerical abundance of introduced species (Introduceda) and the relative biomass of omnivorous species (OMNIb) were finally extracted as the most significant, responding to LHMS and TP, respectively. The final index was expressed as the mean values of the EQRs of these two metrics. The multimetric fish index presented herein could serve as a tool for assessing the ecological quality of natural lakes at broad geographical scale and generally, in the Mediterranean temperate lakes with similar hydromorphological characteristics.},

keywords = {Behavior and Systematics, Ecology, Evolution, General Decision Sciences},

pubstate = {published},

tppubtype = {article}

}