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Special Issue "The WFD 20 Years After—Ecological Status Assessment and Restoration of Aquatic Ecosystems"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Water Quality and Contamination".

Deadline for manuscript submissions: closed (31 July 2021).

Special Issue Editor

Dr. Nikolaos Skoulikidis
E-Mail Website
Guest Editor
Hellenic Centre for Marine Research - Inst. of Marine Biological Resources & Inland Waters, Dept. of Inland Waters, 19013 Anavissos Attikis, Greece
Interests: water quality; ecological status; temporary (intermittent) streams; biogeochemical process; river basin management

Special Issue Information

Dear Colleagues,

Twenty years has passed since the WFD was adopted by the European Parliament. Putting ecosystem integrity at the base of management decisions, the way EU Member States have implemented water management has improved dramatically. An enormous number of new ecological assessment methods has been developed, greatly improving the monitoring and assessment of waterbody ecological status, and thousands of European waterbodies have been classified regarding their status, thereby providing a better basis for their restoration. However, the WFD’s primary objective, i.e., achievement of good status of Europe’s waters, has not yet been accomplished; the results from the second RBMPs show that European aquatic ecosystems remain under pressure from multiple stressors, which affect their functioning, contribute to biodiversity loss, and threaten the long-term delivery of ecosystem services. This Special Issue seeks to summarize and highlight the need for an improvement of the WFD implementation process, particularly focusing on the current practices and future requirements regarding aquatic ecosystems’ monitoring, assessment, management, and restoration.

Dr. Nikolaos Skoulikidis
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • intermittent (temporary) waterbodies
  • cost-effective monitoring
  • ecological status assessment
  • uncertainty
  • traits
  • multiple stressors
  • ecological response
  • functional assessments
  • modeling
  • ecosystem services
  • restoration
  • nature-based solutions
  • ecological flows
  • floodplain rehabilitation

Published Papers (11 papers)

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Research

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Article
Multiple-Facet Diversity Patterns of Aquatic Vegetation in Lakes along a Trophic Gradient
Water 2021, 13(16), 2281; https://doi.org/10.3390/w13162281 - 20 Aug 2021
Viewed by 519
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 [...] Read more.
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. Full article
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Article
Impact of EU Environmental Policy Implementation on the Quality and Status of Greek Rivers
Water 2021, 13(13), 1858; https://doi.org/10.3390/w13131858 - 03 Jul 2021
Viewed by 814
Abstract
Based on historical and WFD-compliant data, the recent inter-annual ecological status and the long-term chemical-physicochemical quality trends of eighteen characteristic Greek rivers have been assessed and interpreted in view of implementing EU environmental policies and the evolution of human pressures. Considering predominating poor [...] Read more.
Based on historical and WFD-compliant data, the recent inter-annual ecological status and the long-term chemical-physicochemical quality trends of eighteen characteristic Greek rivers have been assessed and interpreted in view of implementing EU environmental policies and the evolution of human pressures. Considering predominating poor ecological status in most of the river outflows, the strengths and weaknesses of the WFD implementation have been highlighted. The long-term decrease of ammonium and nitrite concentrations along with relatively low recent BOD5 levels, indicate a general improvement of WWTP infrastructure in Greece and the other riparian countries, whereas the improvement of nitrate quality is attributed to the reduction of fertilizers use, and possibly, to the successful application of the Nitrates Directive in certain basins. Despite capacity building in governance and administrative infrastructure the recent years, River Basin Management Plans (RBMPs) are being implemented centrally, largely mechanistically, with minor public participation. Regarding WFD implementation weaknesses and gaps, concrete proposals have been formulated considering both policy/administrative and technical issues. To efficiently conserve and restore aquatic ecosystems, the forthcoming RBMPs should be consistent with ecosystem services principles focusing on nature-based solutions, along with changing attitudes of the state authorities and the public. Full article
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Article
“One Out–All Out” Principle in the Water Framework Directive 2000—A New Approach with Fuzzy Method on an Example of Greek Lakes
Water 2021, 13(13), 1776; https://doi.org/10.3390/w13131776 - 27 Jun 2021
Viewed by 610
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 [...] Read more.
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. Full article
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Article
Suggested Sampling Methodology for Lake Benthic Macroinvertebrates under the Requirements of the European Water Framework Directive
Water 2021, 13(10), 1353; https://doi.org/10.3390/w13101353 - 13 May 2021
Viewed by 413
Abstract
The estimation of the number of samples required for reliably monitoring lakes’ benthic macroinvertebrates is difficult due to the natural variability and cost and time constraints. To determine a statistically robust and effective sampling design, we collected benthic macroinvertebrate samples from 15 Greek [...] Read more.
The estimation of the number of samples required for reliably monitoring lakes’ benthic macroinvertebrates is difficult due to the natural variability and cost and time constraints. To determine a statistically robust and effective sampling design, we collected benthic macroinvertebrate samples from 15 Greek natural lakes. We compared the spatial and temporal variability of the benthic macroinvertebrate community composition to identify differences among lakes, between lake zones (sublittoral and profundal) and sampling periods. Furthermore, we examined the sampling precision and determined the number of required samples to attain maximum taxa richness. The diminution of the sampling effort was estimated and the desired precision level, considering different benthic macroinvertebrate abundances, was modelled. No temporal or spatial variation between lake zones was observed in communities’ compositions. The precision of our sampling design was adequate, and rarefaction curves revealed an adequate taxa richness (>70%). The developed model could be applied to assess the required sampling effort in lakes within the Mediterranean ecoregion with similar benthic macroinvertebrate abundances. Full article
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Article
Tracking the Causes of a Mass Fish Kill at a Mediterranean River within a Protected Area
Water 2021, 13(7), 989; https://doi.org/10.3390/w13070989 - 03 Apr 2021
Viewed by 580
Abstract
In this study, an extreme event observed at the intermittent Mediterranean Bogdanas River within the territory of the protected area of the National Park of Lakes Koronia-Volvi and Macedonian Temp that led to a mass fish kill was investigated. We aimed to define [...] Read more.
In this study, an extreme event observed at the intermittent Mediterranean Bogdanas River within the territory of the protected area of the National Park of Lakes Koronia-Volvi and Macedonian Temp that led to a mass fish kill was investigated. We aimed to define the main pressures affecting water quality and biota, specifically fish. No organic poisons, pesticides or heavy metal concentrations were detected in fish tissue, while high values of BOD5, COD, TN and conductivity were measured in water samples. These results, combined with the prevailing hydroclimatic factors (high temperatures and low water flow), lead to the assumption that mass fish mortality was triggered by high organic loads discharged from an upstream point source of pollution, and in particular an active landfill. Full article
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Article
Setting the Phosphorus Boundaries for Greek Natural Shallow and Deep Lakes for Water Framework Directive Compliance
Water 2021, 13(5), 739; https://doi.org/10.3390/w13050739 - 09 Mar 2021
Cited by 1 | Viewed by 517
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 [...] Read more.
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. Full article
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Article
Diversity of Alien Macroinvertebrate Species in Serbian Waters
Water 2020, 12(12), 3521; https://doi.org/10.3390/w12123521 - 15 Dec 2020
Cited by 1 | Viewed by 810
Abstract
This article provides the first comprehensive list of alien macroinvertebrate species registered and/or established in aquatic ecosystems in Serbia as a potential threat to native biodiversity. The list comprised field investigations, articles, grey literature, and unpublished data. Twenty-nine species of macroinvertebrates have been [...] Read more.
This article provides the first comprehensive list of alien macroinvertebrate species registered and/or established in aquatic ecosystems in Serbia as a potential threat to native biodiversity. The list comprised field investigations, articles, grey literature, and unpublished data. Twenty-nine species of macroinvertebrates have been recorded since 1942, with a domination of the Ponto-Caspian faunistic elements. The majority of recorded species have broad distribution and are naturalized in the waters of Serbia, while occasional or single findings of seven taxa indicate that these species have failed to form populations. Presented results clearly show that the Danube is the main corridor for the introduction and spread of non-native species into Serbia. Full article
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Article
Integrating In Situ and Ocean Color Data to Evaluate Ecological Quality under the Water Framework Directive
Water 2020, 12(12), 3443; https://doi.org/10.3390/w12123443 - 08 Dec 2020
Cited by 3 | Viewed by 718
Abstract
The Water Framework Directive (WFD) aims at evaluating the ecological status of European coastal water bodies (CWBs). This is a rather complex task and first requires the use of long-term databases to assess the effect of anthropogenic pressure on biological communities. An in [...] Read more.
The Water Framework Directive (WFD) aims at evaluating the ecological status of European coastal water bodies (CWBs). This is a rather complex task and first requires the use of long-term databases to assess the effect of anthropogenic pressure on biological communities. An in situ dataset was assembled using concomitant biological, i.e., chlorophyll a (Chl a) and environmental data, covering the years from 1995 to 2014, to enable a comprehensive assessment of eutrophication in the Western Iberia Coast (WIC). Given the temporal gaps in the dataset, especially in terms of Chl a, satellite observations were used to complement it. Positive relationships between Chl a 90th percentile and nitrogen concentrations were obtained. The Land-Uses Simplified Index (LUSI), as a pressure indicator, showed no relationship with Chl a, except in Galicia, but it highlighted a higher continental pressure in the Portuguese CWBs in comparison with Galician waters. In general terms, the trophic index (TRIX) showed that none of the CWBs were in degraded conditions. Nevertheless, the relatively high TRIX and LUSI values obtained for the water body in front of Tagus estuary suggest that this area should be subject to continued monitoring. Results highlighted the usefulness of satellite data in water quality assessments and set the background levels for the implementation of operational monitoring based on satellite Chl a. In the future, low uncertainty and harmonized satellite products across countries should be provided. Moreover, the assessment of satellite-based eutrophication indicators should also include metrics on phytoplankton phenology and community structure. Full article
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Article
Aquatic Worm Assemblages along the Danube: A Homogenization Warning
Water 2020, 12(9), 2612; https://doi.org/10.3390/w12092612 - 18 Sep 2020
Cited by 1 | Viewed by 543
Abstract
In this study, we analyzed the impacts of different environmental conditions on aquatic worm communities along the Danube River, based on two longitudinal surveys, the Joint Danube Surveys 2 and 3 (JDS; 2007 and 2013). We identified the most important environmental factors (among [...] Read more.
In this study, we analyzed the impacts of different environmental conditions on aquatic worm communities along the Danube River, based on two longitudinal surveys, the Joint Danube Surveys 2 and 3 (JDS; 2007 and 2013). We identified the most important environmental factors (among analyzed groups) that shape worm communities: hydromorphlogical alterations, flow velocity and substrate (HYMO group), dissolved oxygen, nitrates and nitrites (physico-chemical parameters), zinc and nickel (metals), monobutyltin cation, benzo(b) fluoranthene and benzo(k)fluoranthene, polychlorinated biphenyls PCB 77 and PCB 118 (selected chemical determinants—organotin compounds, Polycyclic aromatic hydrocarbons—PAHs and PCBs). A homogenization of species composition of Oligochaeta assemblages along the Danube was confirmed. As one of main factors related to biotic homogenization, hydromorphological alterations represented by similar changes in flow velocity and substrates along Danube’s course could be singled out. Our results indicate that Oligochaeta could be used for the identification of the level of hydromorphological degradation in large rivers (homogenization), rather than for stressors classified as nutrient and organic pollutants. Our results provide additional evidence in risk assessment of the environment, contributing in water management and monitoring of the ecological status as proposed by the Water Framework Directive. Full article
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Article
Chorological and Ecological Differentiation of the Commonest Leech Species from the Suborder Erpobdelliformes (Arhynchobdellida, Hirudinea) on the Balkan Peninsula
Water 2020, 12(2), 356; https://doi.org/10.3390/w12020356 - 28 Jan 2020
Cited by 1 | Viewed by 958
Abstract
This study is the result of extensive investigations of leeches on the Balkan Peninsula. Our aim was to detect actual and potential (modeled) distributions of common Erpobdellidae species, and to identify their ecological differentiation with respect to the altitudinal and waterbody type gradient. [...] Read more.
This study is the result of extensive investigations of leeches on the Balkan Peninsula. Our aim was to detect actual and potential (modeled) distributions of common Erpobdellidae species, and to identify their ecological differentiation with respect to the altitudinal and waterbody type gradient. Although widespread, these species rarely live together. Intense competition is avoided by preferences for different types of habitats. This was confirmed by Pearson correlation analyses that yielded negative results. Differentiation of these species was clarified by the results of logistic Gaussian regression analyses. While Erpobdella octoculata and Dina lineata have a similar distribution along the altitudinal gradient, they prefer different waterbody types. Erpobdella vilnensis prefers higher altitudes than the other two species. Its preferred habitats are smaller rivers and streams located at altitudes from 400 to 1000 m a.s.l. Although present in all waterbody types, large lowland rivers and standing waterbodies are the preferred habitats of E. octoculata. Fast-flowing springs and streams are mostly inhabited by D. lineata. While the distribution of the species overlaps to a large degree, the ecological preferences of species differ significantly and thus they can be used as confident typological descriptors and indicators of ecological status. Full article
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Review

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Review
Benthic Diatoms in River Biomonitoring—Present and Future Perspectives within the Water Framework Directive
Water 2021, 13(4), 478; https://doi.org/10.3390/w13040478 - 12 Feb 2021
Cited by 2 | Viewed by 734
Abstract
The European Water Framework Directive 2000/60/EC (WFD) has been implemented over the past 20 years, using physicochemical, biological and hydromorphological elements to assess the ecological status of surface waters. Benthic diatoms (i.e., phytobenthos) are one of the most common biological quality elements (BQEs) [...] Read more.
The European Water Framework Directive 2000/60/EC (WFD) has been implemented over the past 20 years, using physicochemical, biological and hydromorphological elements to assess the ecological status of surface waters. Benthic diatoms (i.e., phytobenthos) are one of the most common biological quality elements (BQEs) used in surface water monitoring and are particularly successful in detecting eutrophication, organic pollution and acidification. Herein, we reviewed their implementation in river biomonitoring for the purposes of the WFD, highlighting their advantages and disadvantages over other BQEs, and we discuss recent advances that could be applied in future biomonitoring. Until now, phytobenthos have been intercalibrated by the vast majority (26 out of 28) of EU Member States (MS) in 54% of the total water bodies assessed and was the most commonly used BQE after benthic invertebrates (85% of water bodies), followed by fish (53%), macrophytes (27%) and phytoplankton (4%). To meet the WFD demands, numerous taxonomy-based quality indices have been developed among MS, presenting, however, uncertainties possibly related to species biogeography. Recent development of different types of quality indices (trait-based, DNA sequencing and predictive modeling) could provide more accurate results in biomonitoring, but should be validated and intercalibrated among MS before their wide application in water quality assessments. Full article
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