Search Results (9)

The ecological assessment of rivers under the Water Framework Directive (WFD) requires the use of biological quality elements (BQEs) across defined abiotic types of rivers. However, limited evidence exists on how well biological indices perform across multiple typological classes, particularly under the influence of complex, overlapping stressors. This study evaluated the diagnostic performance of four biological indices (IO—diatoms, MIR—macrophytes, MMI_PL—benthic macroinvertebrates, and EFI + PL—fish) in 16 river sites in southern Poland. These were classified into four abiotic types (5, 6, 12, and 17) and subjected to varying levels of human pressure. Biological, physical and chemical, and hydromorphological data were collected along environmental gradients including conductivity, nutrient enrichment, and habitat modification. Statistical analyses were used to evaluate patterns in community composition and index responsiveness. The IO and MMI_PL indices were the most consistent and sensitive in distinguishing between reference and degraded river conditions. MIR and EFI + PL were more variable, especially in lowland rivers, and showed stronger associations with habitat structure and oxygen levels. Conductivity emerged as a key driver of biological responses across all BQEs, with clear taxonomical shifts observed. The results support the need to consider both typological context and local environmental variation in ecological classification. The findings underscore the need for typology-aware, pressure-specific biomonitoring strategies that combine multiple organism groups and integrate continuous environmental variables. Such approaches can enhance the ecological realism and diagnostic accuracy of river assessment systems, supporting more effective water resource management across diverse hydroecological contexts. Full article

The terms ‘non-native’, ‘non-indigenous’, ‘alien’, and ‘exotic’ refer to species or races that do not occur naturally in an area, i.e., they have not previously existed there, or their dispersal into the area has been mediated by humans. In a broad sense, these terms can refer to species that may originate within the same region or country but not occur naturally in a particular water body until colonization is facilitated by humans. In Bulgaria, some efforts have been made to summarize the distribution of alien fish species, but nothing is known about the translocated species. Here, both groups are considered according to the Water Framework Directive’s (WFD) classification of lotic ecosystems: the main ichthyogeographical regions, the river typology, and the ecological status of the Biological Quality Element (BQE) “Fish”. In total, 7 alien species and 15 translocated species were established, with approximately the same total number of specimens. In general, even though the relative abundance of non-native species reaches 100% in single cases, their total numbers are low, compared to native species. Concerning certain basins/river types, these percentages are slightly higher, due to a complex of parameters determining their distribution: environmental factors (hydromorphological) reflecting the ecological (species’ requirements and tolerance) factors. Some river types are more vulnerable to colonization. The relative abundances of the non-native fish species per sampling site showed a weak connection with the ecological status of the BQE “Fish”. As the distribution of organisms is affected by environmental parameters and biotic interactions, standardized multiannual data, as viewed by the WFD, could become a solid basis for elucidating various aspects of this complex issue. Full article

Freshwater ecosystems have been experiencing various forms of threats, mainly since the last century. The severity of this adverse scenario presents unprecedented challenges to human health, water supply, agriculture, forestry, ecological systems, and biodiversity, among other areas. Despite the progress made in various biomonitoring techniques tailored to specific countries and biotic communities, significant constraints exist, particularly in assessing and quantifying biodiversity and its interplay with detrimental factors. Incorporating modern techniques into biomonitoring methodologies presents a challenging topic with multiple perspectives and assertions. This review aims to present a comprehensive overview of the contemporary advancements in freshwater biomonitoring, specifically by utilizing omics methodologies such as genomics, metagenomics, transcriptomics, proteomics, metabolomics, and multi-omics. The present study aims to elucidate the rationale behind the imperative need for modernization in this field. This will be achieved by presenting case studies, examining the diverse range of organisms that have been studied, and evaluating the potential benefits and drawbacks associated with the utilization of these methodologies. The utilization of advanced high-throughput bioinformatics techniques represents a sophisticated approach that necessitates a significant departure from the conventional practices of contemporary freshwater biomonitoring. The significant contributions of omics techniques in the context of biological quality elements (BQEs) and their interpretations in ecological problems are crucial for biomonitoring programs. Such contributions are primarily attributed to the previously overlooked identification of interactions between different levels of biological organization and their responses, isolated and combined, to specific critical conditions. Full article

The importance of adequate biological assessments of rivers based on aquatic assemblages is essential to establish recovery measures. Macrophyte and macroinvertebrate communities react differently in time and in response strength to diverse stressors. Our hypothesis was that each group response is a result of specific and combined abiotic factors and each stressor’s impact. To address the above, both biological quality elements (BQEs) and values of the ecological quality ratio (EQR) were studied in relation to four abiotic parameters and five physico-chemical stressors. Discrepancies of more than one degree between the ecological status assessments of Bulgarian river sites determined using macrophytes and macrozoobenthos were discussed. The RDA analysis showed that altitude had a determining role in shaping the abundance of macrophyte and macrozoobenthos communities. Aquatic flora richness positively correlated with nitrogen enrichment and macroinvertebrate fauna—with altitude and biochemical oxygen demand (BOD). Nutrients and shading were most significant for the ecological status evaluation defined with both macrophytes and macrozoobenthos. Macrophyte-based EQR was related to oxygen concentration and shading, while macroinvertebrate-based EQR was better at sites with coarser substrates. Among tested stressors, mainly total nitrogen and BOD explained the lower macrophyte-based assessment at half of the studied sites. In conditions of increased nitrogen and BOD, but remaining in the range of good status, macrophytes as primary producers gave a faster and stronger response. Despite the differences in the assessment, both BQEs have higher values in conditions of lower BOD and total phosphorus. Full article

Aquatic macrophytes are one of the four biological quality elements (BQE) used for assessing the ecological status of inland waters according to the EU Water Framework Directive (WFD 2000/60). With this article, we present the methodological approach for the implementation of a WFD compliant macrophyte index to the riverine systems of Greece. In addition to the definition and harmonization of the ecological quality class boundaries, the results from the pilot application of the index and the ecological classification of the monitored river reaches are also presented. Aquatic plants and environmental parameters were sampled from 93 river reaches between 2012 and 2015. A multivariate analysis with optimal scaling (MVAOS) was conducted to define the main stressor gradient and to identify the least disturbed sites and the reference conditions that are required for the derivation of the ecological quality classes. The Macrophyte Biological Index IBMR for Greek rivers (IBMR_GR) was calculated for all the sites and the boundaries for the five quality classes were derived according to the methodology proposed by the Mediterranean Geographic Intercalibration Group (MedGIG). The main findings showed that the hydromorphological modifications were the main environmental stressors that correlated strongly with the IBMR_GR, whereas physicochemical stressors were of lesser importance. More specifically, the first principal component explained 51% of the total variance of the data, representing a moderately strong gradient of hydromorphological stress, whereas the second component explained 22.5%, representing a weaker gradient of physicochemical stress. In addition, the ecological assessment showed that almost 60% of the sites failed the WFD target of the “Good” ecological quality class, which agrees with classification assessments based on other BQEs for Greece and many Mediterranean countries. Overall, this work provides a first assessment of the ecological classification of Greek rivers with the BQE of aquatic macrophytes with significant implications for ecological monitoring and decision making within the frame of the WFD implementation. Full article

Regardless of the efforts of the European Union, freshwaters are in a state of environmental crisis. The Water Framework Directive has established a basis for the protection and restoration of European inland and coastal waters. In parallel, the Birds and Habitats Directives protect, maintain or restore, at favourable conservation status, selected species and habitats under a representative network of protected areas. Hence, the interplay between the EU regulations is of high scientific interest and practical relevance. In this article, Greece is used as a case study to explore whether anticipated synergies between the Water Framework Directive and the Nature Directives result in a better ecological status in the protected areas than in the non-protected ones. We investigated whether the ecological qualities that are defined by three biological quality elements (BQEs) differ between the WFD monitoring sites that are located within the Natura 2000 protected areas and those that are not. We identified a total of 148 river monitoring sites that are located within the Natura 2000 network, which corresponds to 30% of the WFD monitoring network. By employing ordered logit models for each BQE, we found that the ecological quality has the same likelihood to fail the WFD target of “good” quality for sites that are located within and outside the Natura 2000 protected areas. Our results confirmed our hypothesis that the EU directives have little synergy when it comes to restoration of ecological status of Greek running waters, according to the WFD. Full article

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

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

The Water Framework Directive (WFD) aims to monitor continental water bodies in Europe to achieve good ecological status. Indexes based on biological quality elements (BQEs), ecotoxicological tests, and chemical characterizations are commonly used with standardized protocols to assess sediment quality and the associated risks. Here, we compare the results of quality assessment of benthic macroinvertebrates as BQEs as required by the WFD with the results of ecotoxicological tests and assessment of selected persistent organic pollutants (POPs) in sediments of the same eight water bodies in Italy. The aim was to verify if the assessment of quality through macroinvertebrates through POPs analyses and ecotoxicological tools can yield comparable, overlapping, or complementary results. We used the Benthic Quality Index (BQIES) for macroinvertebrates (two different applications), legacy POPs (dichloro-diphenyl-trichloroethane and metabolites (DDTs) and polychlorinated-biphenyls (PCBs)), and the emergence ratio (ER) and development rate (DR) for ecotoxicology. The results showed that the two indices within each approach were highly correlated, but between approaches, each result can lead to a completely different scenario, with rather different results of the assessment of ecosystem quality. The most striking result was that very few significant correlations existed between sediment quality assessment through macroinvertebrates and the risk assessment through analyses of micropollutants and ecotoxicological tests. The highest absolute r-value (0.81) was for the correlation between the BQIES_bottom index and PCBs for micropollutants, whereas all other pairwise comparisons between indices had r-values ranging between 0.07 and 0.53. Our analysis calls for a caveat in the blind application of one or only a few indices of water/sediment quality, as the results of a single index may not represent the complexity of a freshwater ecosystem. Full article