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.

Taxonomic identity and ecological status of two rare orchids from southern western ghats, india

An assessment has been made to identify the rare, endemic and threatened species in the Velliangiri hills of Southern Western Ghats, India. During field explorations, two rare species of terrestrial saprophytic orchids were collected. On critical appraisal and authentication of herbarium specimens, they were identified as Aphyllorchis montana Rchb. f. and Epipogium roseum (D. Don) Lindl. The present paper deals with their correct taxonomic identity, distribution and ecological status.

Regarding the choice of composite indicators of ecological safety of water in the basin of the Siversky Donets

The lack of effective mechanisms of the methods of basin management, control of and responsibility for the ecological state of surface sources of drinking water leads to the fact that the main man-made objects that determine the ecological state of surface water sources are most often located in one oblast, while the production and consumption of the drinking water from those sources occur in the territory of other oblasts, which complicates the effective management of environmental safety of surface water sources. This is especially true for the regions of Ukraine which are poor in surface water resources, located in the basin of the Siversky Donets River, the water bodies of which are the main sources of water supply in the eastern regions of the country. The main consumer of water is Donetsk Oblast (over 50 % of the annual volume), and Kharkiv and Luhansk Oblasts together consume approximately the same volume of water per year (up to 50 % of the annual volume). Therefore, it is important to substantiate the integrated indicators of the ecological status of the water body to improve the environmental safety of surface water sources. The paper shows that oxygen indicators play an important role in the ecology of a water body. They are associated with the assimilative ability of water, the ability of water to decompose organic matter. Therefore, the content of dissolved oxygen and biochemical oxygen consumption in water is of great interest not only in terms of life development, but also as a composite measure of the ecological status of the aquatic environment. The relationship between the value of the combined index of water pollution and the value of biochemical oxygen consumption makes the indicator of biochemical oxygen consumption important for the integrated assessment of water contamination with various organic substances. For the tasks for which we justify the choice of composite measures of the ecological condition of surface waters, it is more important to identify the effects of contamination not directly at the site of contamination, but at some distance from it and after some time. Therefore, the use of the amount of dissolved oxygen and biochemical oxygen consumption as indicators that characterize the oxidation of pollutants present in water is the most appropriate for the tasks of timely monitoring of water bodies. Therefore, as a composite indicator for characterizing the condition of the watercourse and conducting timely monitoring, we chose oxygen indicators.

Phytoplankton as an indicator of the current ecological status of the Ob River

The species composition, taxonomic structure, and the dominant complex of algae, and the distribution of phytoplankton abundance in the studied watercourse were identified based on data obtained for phytoplankton from the Ob River (from Tomsk to Salekhard) in summer 2019. Green algae (division Chlorophyta) make up the basis of the phytoplankton abundance in the river. The dominant complex is represented mainly by centric diatoms (genera Aulaсoseira, Cyclotella, Stephanodiscus) and non-heterocyst forms of cyanoprokaryotes (genus Aphanocapsa). The numbers and biomass of phytoplankton gradually decrease downstream of the Ob River; below the confluence of the Irtysh River, the edge effect occurs: increase in the diversity and density of organisms at the boundaries of ecosystems. Compared to the previous studies, the proportion of green and euglena algae, and cyanoprokaryotes in the taxonomic spectrum of phytoplankton increased, the composition of the dominant complex enriched, including due to non-heterocyst forms of cyanoprokaryotes, and the trophic status of the river increased to the category of eutrophic waters.

Eco-Assessment of Streams of Konya Closed River Basin (Turkey) Using Various Ecoregional Diatom Indices

Ecological assessments of freshwater ecosystems based on diatom metrics are an important issue to attain environmental sustainability. The present study aimed to evaluate differences in the diatom-stressors relationship in relatively least disturbed streams in the Konya closed river basin using multivariate analyses and to bio-assess streams by application of different ecoregional diatom indices. Cocconeis euglypta, Cymbella excisa, Cocconeis placentula, and Achnanthidium minutissimum are the most contributing species to the dissimilarity of sampling stations between rainy and dry seasons and also between altitude (A2 800-<1600 m and A3 ≥1600 m) groups. A strong (82.8%) correlation between diatom species and stressors was expressed by the first two axes of canonical correspondence analysis. Diatom species displayed distinct responses to environmental variables (electrical conductivity, Ni, Cu, B, and altitude) playing important roles on the distribution of diatom species. Diatom indices indicated different ecological statuses of stations from a bad to a high. European diatom indices except Duero Diatom Index-DDI and Trophic Diatom Index-TDI showed well responses to the eco-assessment of streams and indicated high ecological status for the least disturbed sampling stations symbolized as S16, S20, S24, S25, S27-29, S37, and 39. These results were also supported by abiotic evaluation. Among diatom indices, although TIT was more competitive in the bio-assessment of streams, it is necessary to increase its species list by determining their trophic weights in future studies. This indicates that the revision of ecoregional specific diatom metrics with the enhancement of diatom species numbers according to their ecological preferences is needed to correctly interpret the water quality.