Water quality for triathlon and open water swimming competitions in Brazilian freshwaters

In high-performance competitive activities, there can be intense and prolonged exposure to water during swimming components of the competition. Therefore, water quality assessments with reference to standards are desirable to ensure athletes’ health. We evaluated whether the official criteria established for primary contact recreation in Brazilian freshwaters (CONAMA Directive 274/2000), and an integrated index of bathing conditions in Brazil (ICB), are consistent with the water quality standards stipulated by the International Triathlon Union (ITU). The water quality of Lake of Ingleses, an important venue for triathlon and open water swimming near Belo Horizonte, Minas Gerais, Brazil, was assessed between 2003 and 2019. Results for E. coli, cyanobacteria density, and pH were favorable for contact recreation and competitions at the lake. Of the variables considered, only turbidity, used as a proxy indicator of visual water clarity, was unsuitable during part of the monitoring period. The ICB agreed with the ITU standards for Very Good and Excellent quality classes and is recommended as a tool for screening sites considered for competitions in Brazilian freshwaters. However, the Brazilian national criteria for contact recreation only present standards for E. coli and pH, which is insufficient coverage of attributes affecting primary contact suitability of water in high-performance sports activities.

Predation of Glossiphonia weberi (Blanchard, 1897) on the invasive snail Physella acuta (Draparnaud, 1805) in the presence of an alternative prey

The North American freshwater snail Physella acuta has invaded and colonized a wide range of freshwater habitats, globally. Resembling other invasive species, P. acuta has several negative impacts on the invaded freshwater ecosystems, which calls for its regulation, preferably through biological control. The malacophagous leech Glossiphonia weberi, native to West Bengal, India, had been previously reported as a potential biocontrol agent of P. acuta. In this experiment, we observed the predation potential and prey preference of G. weberi on P. acuta in the presence of a native snail, Gyraulus convexiusculus. The results suggest that in all instances, G. weberi consumed less G. convexiusculus compared to P. acuta. In complex habitats, G. weberi showed significant prey preference to P. acuta except in the habitat characterized by the presence of pebbles. The complex habitats bear a significant (p < 0.05) negative impact only in the case of predation on P. acuta when present with conspecific but not in heterospecific prey conditions. Therefore, G. weberi qualifies as a useful biological control agent that can affect the colonization and expansion of the invasive snail P. acuta, even in the presence of alternative prey.

Transformation of the morphometry of Lake Osieckie – largest lake in the Holy Cross region

The paper presents the analysis of the transformation of Lake Osieckie, the largest lake in the Holy Cross region until 2016. It is a valley lake that according to cartographic materials had undergone no changes in the shoreline since ca. 1938. The nearby activity of a sulphur mine required building three dikes on the lake, dividing it into four independent water bodies. The paper presents the analysis of their morphometric properties in comparison to those of the original lake. Although the basins of the new lakes are of natural origin, the currently existing four lakes can be described as quasi-natural.

Seasonal variation of algal diversity with reference to water quality in Jagadishpur Reservoir, Nepal

The study of the importance of physicochemical parameters of water for algal growth and development in Jagdishpur Reservoir was carried out in the present research. Occurrence of algal species and values of water quality parameters also indicate the ecological nature and the present status of the reservoir. Water samples were collected from Jagdishpur Reservoir in Kapilvastu District (Nepal), in two seasons (wet and dry). The following physicochemical parameters of water were analyzed: temperature, pH, dissolved oxygen, alkalinity, concentration of nitrates and phosphates, free CO2, hardness, conductivity, total dissolved solids. The values of free CO2, hardness, phosphate, temperature, and dissolved oxygen were high in wet season while alkalinity, nitrate, conductivity and total dissolved solid were high in dry season. Altogether 81 algal species belonging to 53 genera and 6 classes were recorded. Higher number of algal species was recorded in the dry season rather than in the wet season. The highest number of species was noted among Chlorophyceae, followed by Cyanobacteria > Bacillariophyceae > Euglenophyceae > Crysophyceae and Dinophyceae. Cosmarium had the highest number of species (13) among all genera. During the wet season, Cosmarium, Calothrix and Phormidium were the genera with the highest number of species while Bulbochaete, Trachelomonas and Gomphonema were genera with the lowest number of species. During the dry season, Cymbella, Cosmarium and Rhopalodia were genera with highest number of species while Euglena, Gloeotrichia and Trachelomonas were genera with lowest number of species. Algal diversity was positively correlated with the increase of alkalinity, conductivity and TDS, while negatively correlated with free CO2, hardness, concerntration of phosphates and nitrates, DO, pH and temperature. Shannon–Weiner diversity index value was higher during the dry season than in the wet season.

Light pollution affects the coastal zone of Lake Baikal

The role of light pollution in aquatic ecosystems functioning has increased in recent times. In addition, the effect of such pollution has mostly been studied in coastal marine ecosystems, leaving freshwater ecosystems much less studied. In the p resent work, we investigated the effect of light pollution on the coastal zone of the ancient Lake Baikal ecosystem. Both a laboratory experiment and field research were conducted. The results of the experiment showed the presence of statistically significant differences (р =0.009) between fish feeding on amphipods with and without daylight conditions, while there were no such differences between daylight and artificial light conditions. At the same time, video recordings revealed both a low number of specimens and a low species diversity of amphipods near to the village with a developed system of street lights, while in the village with a nearly nonexistent light system, the species diversity and a number of amphipods were much higher. One plausible explanation for such influence of light pollution on the quality and quantity of Baikal amphipod fauna might be the sum of several factors such as high water transparency and daily vertical migrations of amphipods.

The tardigrade cuticle

Tardigrades (phylum Tardigrada) are aquatic microecdysozoans that have adapted to survive extreme conditions through the formation of cysts or ametabolic tuns. Their body is covered by a cuticle that plays an important role in their life cycle, including their response and adaptation to environmental challenges. Cuticular characteristics are a critical component of tardigrade taxonomy. Therefore, research has often been focused on the relationship between cuticular morphology and ultrastructure and the evolutionary and phylogenetic positioning of the phylum and individual species herein. However, a deeper insight into the ultrastructural characteristics and chemical composition of the tardigrade cuticle is needed. This knowledge is important not only for a better understanding of tardigrade physiology and ecology but also for the development of efficient microinjection and/or electroporation techniques that would allow for genetic manipulation, opening new avenues in tardigrade research. Here, we review data on cuticle ultrastructure and chemical composition. Further, we discuss how the cuticle is affected during moulting, encystment, cyclomorphosis, and anhydrobiosis. Our work indicates that more systematic studies on the molecular composition of the tardigrade cuticle and on the process of its formation are needed to improve our understanding of its properties and functions.

Aquatic tardigrades in Poland – a review

The diversity, distribution and ecology of aquatic Tardigrada in Poland remain poorly known. We reviewed the literature focused on tardigrades in Poland and recognized only 15 aquatic taxa which were reported from various freshwater and marine habitats. Among them, 12 are freshwater and three are marine taxa. Hypsibius dujardini is Poland’s most widely-distributed hygrophilous species, but it re presents rather a complex of cryptic species and their diagnosis requires integrative approaches. Most reports of aquatic tardigrades in Poland are accidental findings mostly from water bodies in Tatra Mountains or from lakes in Masurian Lake District. Some species were also reported from small ponds or wastewater treatment plants in other regions like Małopolska or Wielkopolska Provinces.

Hydrological modeling of rainfall-runoff of the semi-arid Aguibat Ezziar watershed through the GR4J model

The management of water resources requires as a first step the modeling of rainfall-runoff. It allows simulating the hydrological behavior of the basin for a good evaluation of the potentiality of this in terms of water production. There are different hydrological models used for water resource assessment, but conceptual models are still the most used due to their simple structure and satisfactory performance. In this study, t he performances of the conceptual model of rainfall and runoff (GR4J) modeled under R with the AirGR package, are used to Aguibat Ezziar the subbasin of the Bouregreg basin in Morocco. The enormous amount of data required and the uncertainty of some of the m makes these models of limited usefulness. The GR4J model allows evaluation of the runoff rates and describes the hydrological behavior of the Aguibat Ezziar watershed, which presents the aim behind writing this paper. A period from 2003 to 2017 has been selected. This period has been divided into two parts: one for calibration (2003-2006), and one for validation (2013-2016). After the calibration of the model and following the performance obtained (Nash higher than 0.72) we can say that the GR4J model behaves well in the Aguibat Ezziar catchment area.

Current state of bacterial community of Lake Ladoga

The data are presented on a quantitative assessment of the bacterioplankton community of Lake Ladoga and total bacterial numbers dynamic in the period from 2009 to 2019. The trophic state of the lake and water quality in different areas have been characterized by microbiological parameters. Maximum concentrations of microorganisms and highest water temperatures were commonly observed in the shallow coastal area (Volkhov Bay, up to 6.40 ×106 cells ml−1), and minimum – in the deepest part of the lake (ca. 0.45 ×106 cells cm−3). The bacterial abundances correlate with water temperatures both within each year of observations and over the whole study period. The trophic state of the lake expressed by the total bacterial numbers during summer seasons closely matches the state during the first decade of the 21st century. In the period of 2009-2019, the trophic state varied from oligo-mesotrophic in the hypolimnion of deep-water areas to mesotrophic eutrophic in the shallow southern coastal area, which corresponds to the trophic state indicated by chlorophyll-a concentrations. Within the previous decade (2000-2008), the waters of Lake Ladoga were “clean” and “especially clean”, while during the 2017-2019 period, water masses all over the lake can be identified as “especially clean”. From 2017 to 2019 the coccoid forms of bacterial cells prevailed over rod-shaped cells comprising 57.6 ±5.1% (2017), 64.4 ±4.5% (2018), 61.1 ±4.6% (2019), which imply the high quality of the waters.

Were there any changes in zooplankton communities due to the limitation of restoration treatments?

Zooplankton is a good indicator of water quality state. Analysing the species composition and abundance, it is possible to assess the condition of the water body and predict the direction of changes. The aim of the study was to analyse the zooplankton in a shallow urban lake, in which restoration was limited to one method, i.e. wind-aeration. The results were compared with the earlier data obtained during sustainable restoration (three methods: wind-aeration, phosphorus inactivation, biomanipulation) and before the restoration period. The zooplankton was sampled monthly in 2015 and 2016 in the deepest place of the lake from the surface to the bottom. The trophic state was determined based on rotifer trophic state index for lakes (TSIROT). Although the species composition of zooplankton communities varied very little among the restoration periods (Keratella cochlearis f. tecta mainly dominated), significant changes in the abundance of zooplankton were found in the analysed lake. The maximum of total abundance was noted in 2015, almost 5500 ind. L−1, and in the next year its decrease was almost 3-fold, to ca. 1800 ind. L-1. Based on TSIROT, the water was still eutrophic. Leaving only one method of restoration (namely, oxygenation of the bottom waters) proved insufficient to support the development of crucial organisms as cladocerans. The changes in the abundance could have resulted more from seasonal changes than from the effects of aeration. A reduction in species number and maintaining a high proportion of rotifers typical for a high trophic state indicated a return of the ecosystem to its pre-restoration state. High variability in the rotifer abundance indicated a continuous imbalance of the ecosystem. Previous restoration treatments using several methods simultaneously showed better effectiveness. The change of strategy of restoration before obtaining a stable improvement of water quality destroyed previously achieved effects.