Statistical approaches to explore the linkages between physicochemical parameters and BQEs, and set river nutrient threshold concentrations in Hungary

The objective of the Water Framework Directive (WFD) is to achieve good ecological status in surface waters by 2027. To make a proper evaluation of the ecological status of watercourses, it is necessary to harmonize class boundaries for chemical and biological quality elements (BQEs). This paper aims to explore the linkages between physicochemical parameters and BQEs and set river nutrient threshold concentrations that support good ecological status. Regression and mismatch methods were applied to find the relationship between phytoplankton (PP) and phytobenthos (PB) environmental quality ratio and mean total phosphorus (TP) and total nitrogen (TN) concentrations. Nutrient thresholds have been suggested for several water types, which are varied in the case of highland rivers 1.8–6.2 mg TN/l, 180–400 μg TP/l; in the case of lowland rivers 1.4–5.0 mg TN/l, and 100–350 μg TP/l. These values are similar to what other studies found, but the relationship between biology and nutrients was weaker. Besides nutrients, additional data of measured dissolved organic carbon, 5-day biochemical oxygen demand, chemical oxygen demand with potassium permanganate method, and information about hydromorphological features were involved in the analysis. The research demonstrates that random forest can be used as a nonlinear, multiparametric model for predicting biological class from five variables with 35–81% error for PP and with 18–47% error for PB.

Evaluation of the Use of Some Benthic Macro-invertebrate Multimetric Indices Associations with Environmental Variables in Ecological Assessment of Some Ethiopian Rivers

The ecological status of six selected rivers which are found around central Ethiopia and North Shewa Zone and exposed to environmental stresses at varied extent, was studied using biological quality elements (BQE). One thousand one hundred thirty three (1133) individuals of macroinvertebrates, from 22 families and 5 orders of insects, were collected from the rivers. Seven metrics that had low correlation (p>0.05) were selected to calculate the final B-IBI and the result showed that both sites of Akaki, Sebeta and Jemma Rivers had poor water quality whereas Beresa, Chacha and Mojo (upstream site) had relatively better water quality. Canonical Correspondence Analysis (CCA) showed that Tabanidae, Syrphidae, Culicidae, and Canidae was more strongly correlated with temperature but strongly and negatively with pH, Dissolve Oxygen (DO) and Nitrate. The result implied that the change in abundance of these groups of macroinvertebrates could indicate the change in pH, DO and Nitrate. pH and DO were significantly (p < 0.05) and positively correlated with % Ephemeroptera and% Baetidae. On the other hand, DO showed strong but negative correlation % Oligochaeta, % Non-Insect and Hillsenhoff Family Biotic Index which implied that that the change in pH and level of organic pollution can be easily monitored using these metrics.HYDRO Nepal JournalJournal of Water Energy and EnvironmentIssue: 20Page: 49-54

Towards the implementation of the Water Framework Directive in Mediterranean transitional waters: the use of macroinvertebrates as biological quality elements

During the last decade the Water Framework Directive (WFD) has driven scientific community endeavours towards the development of assessment tools to determine the Ecological Quality Status (EQS) for all surface waters, including transitional waters (TWs). Macroinvertebrates being used as Biological Quality Elements encouraged the development of distinct multimetric and multivariate indices, initially based on taxonomic approaches. Those indices were mostly developed for the marine environment and applied extensively on TWs. The main discrepancies in the ecological quality status assessment arise on TWs, partially due to the difficulty in discriminating the effects of natural stress from anthropogenic impact. As a response, indices following functional approaches are being developed and applied in assessing the EQS in these environments. Next, the validation and intercalibration of the metrics as well as the settlement of reference conditions are additional sources of variability inherent to any assessment. This paper aims at briefly presenting the different steps needed for the implementation of WFD on Mediterranean TWs. It highlights existing difficulties and possible research lines to be explored in order to reduce sources of variability and better assess the status of such water bodies.

Trophic conditions in rivers and streams – significance for biological quality elements of the European Water Framework Directive

In the past, saprobic and trophic conditions were both used as indicators to assess and monitor the quality of surface water bodies. Now, with the introduction of the European Water Framework Directive (WFD), the focus in the assessment of aquatic systems has shifted towards better integration of biocoenotic parameters, expressed as biological quality elements. With this change, saprobity is still used, at least as partially, in the evaluation of benthic invertebrate fauna. The term ‘trophic status’, however, no longer appears as a separate criterion. It is the aim of this paper to show that all quality components depend to a greater or lesser extent on the water bodies' trophic status, so that this term will maintain its significance as a key influencing factor.

Role of hydrological and hydromorphological factors in ecological quality of medium-sized lowland streams

The development of biological communities is an important research issue regarding biological quality elements. However, it is still uncertain how different organism groups and their metrics are affected by different environmental factors. A study of high-quality sites of medium-sized lowland streams typical for Latvia (ecoregion Baltic province) was carried out with an emphasis on hydrological and hydromorphological characteristics. The investigations were carried out within the STAR project using the project designated standard methods. We found that the level of saprobity according to benthic macroinvertebrates was mainly linked with substrate type and stream depth. The trophic diatom index for diatoms on a soft substratum had a negative correlation with altitude and a positive correlation with distance from the source and also stream depth. There were no significant correlations between macrophyte trophic indices and environmental factors associated with stream hydrological conditions. The European fish index was influenced mainly by stream width and distance from the source, which agrees with the results of other researchers. In general, a direct or indirect role of hydrological and hydromorphological factors was evident in the forming of communities characterizing stream ecological quality.

Towards candidature of the Crno jezero (Black Lake) (Durmitor, Montenegro) as a high ecological status (HES) site of the Dinaric Western Balkan ecoregion

The aim of this study was to assess whether the Crno jezero (Black Lake) could be designated as a site possessing specific reference conditions of a glacial lake in the Dinaric Western Balkan ecoregion. The results of a Lake Habitat Survey (LHS), analysis of macrophytes and a basic water quality assessment indicate that the lake is in a near pristine state, particularly with regard to its hydromorphological status, and that it fulfills the requirements of High Ecological Status (HES), as set by the Water Framework Directive. However, to confirm these preliminary findings, an integrated assessment of the ecological and chemical status, using other biological quality elements and a full set of physico-chemical parameters, is necessary.