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The Wadi El-Rayan is a depression in the Fayoum oasis collecting agricultural drainage water from the Fayoum. Since 1973, this drainage water formed two man-made lakes. Twenty years ago, a third lake, called Lake Magic was formed. Since this newly formed lake was not yet studied, in January of 2019 we conducted research related to its physico-chemical (ion composition, nutrients, heavy metals, etc.) and biological (phyto-, bacterio- and zooplankton) characteristics. The depth of the lake ranged from 1.5 to 9.0 m, water transparency was up to 4.0 m, and the water temperature was 13.6 °C. The average salinity was 29.1 g/l, and the salinity of drainage waters from agricultural fields was 2.9 g/l. A total of 28 phytoplankton species was identified belonging to Bacillariophyceae (eight species), Dinophyceae (three species), Cyanobacteria (seven species), Chlorophyceae (nine species) and Conjugatophyceae (one species). Chlorophyll a content varied from 14.3 to 24.2 μg/l. In zooplankton, there were three species of Ciliophora, five of Rotifera, and two Copepoda as well as Nematoda and Cirripedia larvae. Salinity in Lake Magic was much higher than in drainage waters coming in the lake. This is a result of a strong salinity increase in Lake Magic after its creation due to climate aridity, and salinity may markedly increase during the next 20 years along with the sharp changes of the lake's ecosystem.

Salinity is one of the most important factors in aquatic ecosystems, but its filtering role in the Diptera community species composition is still poorly studied. This issue was studied in the diverse Crimean water bodies. A total of 425 samples were collected from freshwater to hypersaline waters. In 73% of the 425 samples examined, representatives of Diptera were found; their larvae and pupae belonged to seven families. Сhironomid species composition was analyzed in 47 samples. The most common were Chironomidae, which were in 94% of samples with Diptera, Ceratopoganidae were in 8% of samples, Ephydridae were in 5% of samples, Simuliidae were in 4% of samples, Culicidae and Chaoboridae were in 4% of samples, and Syrphidae was in only one sample. A total of 14 Chironomidae genera and 21 species and forms were found; 9 of them are new for Crimea. Reduction of the dominance variants in the community, as well as the number of chironomid species, with increasing salinity may indicate an increase in the filtering role of salinity in the Diptera community species composition that is still poorly studied.

Filamentous green algae Cladophora spp. are cosmopolitans inhabiting waters with different salinity, from freshwater to hypersaline. Eutrophication of marine and inland waters results in the huge development of filamentous green algae, which reach high biomass and occupy large areas in different water bodies. This leads to the strong negative effect on the species richness of communities, significantly reduces the aesthetic value of coastal waters, hampers the recreational use of beaches and the coastline, and complicates industrial water intake and coastal fishing. Harvesting and the use of Cladophora biomass can be an effective tool to remediate eutrophic waters. Cladophora spp. are also among the most promising subjects to use in the development of integrated multi‐trophic aquaculture; there is a big potential to use it. Aquaculture is one of the potential uses. To plan the use of a resource, business needs to know the availability and quantity of the resource, the price of the resource, as well as for what benefit and how it can be used. This review summarizes and analyses existing data to answer these questions. Cladophora biomass can be used for food for humans, livestock, cultivated fish and shrimps, as fertilizers, in the energy sector (biogas and biodiesel), and different industries. The use of Cladophora in medicine and pharmacology is one of the most profitable promising ways to utilize the biomass. This review shows that Cladophora biomass is an unlimited, low cost and valuable resource for medicine and pharmacology. [ABSTRACT FROM AUTHOR]

Measuring the linear characteristics of chironomid larvae is easier and faster than measuring their mass. The relationships between them are approximated by parabolic equations. Generalized equations are provided for all chironomid larvae. However, these relations vary in different water bodies. Measurements of 1424 chironomid larvae representing several species were taken in Crimean waters with salinity ranging from 0 to 280 PSU. There was a high correlation between three traits. In the case of Baeotendipes noctivagus and Cricotopus gr. sylvestris, dimorphism was found in the "head capsule length– width" relationship. Salinity affects the head capsule. The exponent "b" varied from 1.43 to 3.06 in the "body length-mass" equation for B. noctivagus, and from 1.943 to 2.592 for C. gr. sylvestris. It is inappropriate to use only one coefficient "b" for all chironomid larvae. In B. noctivagus and Paratanytarsus confuses, the mass of one-size larvae decreased with increasing salinity. Salinity is not the only factor affecting the size and mass of chironomid larvae. [ABSTRACT FROM AUTHOR]

Summary: Sivash Bay is the largest hypersaline lagoon in the world. In 1963-1975 the North Crimean Canal was constructed, with water from the River Dnieper and discharge of drainage water collected from agricultural lands into Sivash Bay. Salinity in Sivash Bay began to drop, resulting in a new brackish water ecosystem. The political decision to stop supplying water from the River Dnieper to the Canal was made in 2014, and the discharge of fresh water into the lagoon ended, resulting in an increase in salinity up to 60-75 g l−1. This study showed that the abundance of meiobenthos increased, with Nematoda dominating. The composition of nematode species in the lagoon has not previously been studied. Using samples from 1979, 2013 and 2015, 50 nematode species and forms were identified in 1979, 32 in 2013 and 21 in 2015. The species composition of nematodes at different periods was significantly different. The average abundance of nematodes was 134 198 ind. m−2 in 2013 and 606 660 ind. m−2 in 2015. [ABSTRACT FROM AUTHOR]

A considerable part of the world's population is currently experiencing a severe scarcity of freshwater and nutrition. Inland aquaculture has the fastest growth in fresh waters, and this contributes to the eutrophication of freshwater bodies. The increase in freshwater aquaculture impacts on the increasing demand for fresh water. A way to overcome this is to develop aquaculture in saline lakes. This article discusses how saline and hypersaline lakes may contribute to overcome this problem and gives a list of fish and shrimp species that can be cultivated in saline lakes. Successful development of aquaculture depends on a healthy cultured stock of commercial fish and shrimps. A sustainable healthy stock of fish and shrimps can be only maintained using live food for the cultured fish larvae, fry and fingerlings. As well as Artemia spp. there are many other crustacean species with the potential for growing in hypersaline waters. At least 26 copepod species around the world can live at a salinity above 100 g/L with 12 species at a salinity higher than 200 g/L, and these all have excellent nutritional value. There is a high potential to use eukaryotic organisms of different taxa in saline / hypersaline aquaculture for food, agri-aquaculture, different industries and as food supplements. [ABSTRACT FROM AUTHOR]

Coastal Lake Bardawil (Egypt) is one of the largest hypersaline lakes in the world. In 2009-2010, the authors studied composition, distribution and seasonal dynamics of copepods at 12 sites. A total of 10 species of copepods were recorded in zooplankton during the study period, including 5 Calanoida, 2 Cyclopoida and 3 Harpacticoida. Oithona nana was the most common and most abundant species. All copepods in the lake can be divided into three groups: 1) planktic species that form stable populations, 2) species of Mediterranean plankton incidentally entering the lake from the adjacent sea area, 3) benthic Cyclopoida and Harpacticoida that can be abundant in plankton. Two species - Acartia tonsa and A. danae were recorded here for the first time. The total abundance of copepods in the lake was significantly higher (90 times on average) compared to that observed in 2008-2009 in the waters of the Egyptian Mediterranean Sea. Since 1967, the complex of common and dominant copepod species in the lake has changed significantly. The total average annual copepod abundance varied: in 2002 - it was about 4000 ind. m-3, in 2004 - 152 000 ind. m-3, in 2005 - about 25 300 ind. m-3, and in 2009-2010 - about 56 000 ind. m-3. [ABSTRACT FROM AUTHOR]

Lagoon Bardawil, belonging to the few hypersaline lagoons in the Mediterranean Sea, is located in the middle of the Sinai coast. Composition, distribution, and seasonal dynamics of large planktonic tintinnids and foraminifera at 12 stations in the lagoon were studied in 2009 and 2010. Fifteen species of Ciliophora (Tintinnina) and two species of Foraminifera were identified. The occurrence of different species varied greatly in the study period: two species were found in 42% to 49% of all samples, two species in 21% to 23%, 4 species in 10% to 20%, and 10 species in 1% to 5%. Only three species were found throughout the year. The average total number of all recorded protozoa varied from 2333 ind./m³ (spring) to 13,733 ind./m³ (winter): Tintinnina from 1250 ind./m³ (spring) to 12,867 ind./m³ (winter) and Foraminifera from 200 ind./m³ (autumn) to 1083 ind./m³ (spring). The distribution of total abundance of tintinnids and foraminifers in the lagoon area was close to random in summer and spring; during autumn and winter, it was aggregated. Tintinnid and foraminifera studies in Lagoon Bardawil were carried out previously (1985-2010); summarizing all data, it was found that interannual differences may be explained by stochastic causes and nondirected climate fluctuations. [ABSTRACT FROM AUTHOR]

The East Asian freshwater cyclopoid copepods Mesocyclops pehpeiensis (Hu, 1943) and Eucyclops roseus Ishida, 1997, which are new for Europe, were recorded from samples collected in the water bodies of the city of Lugansk, eastern Ukraine. In 2012 the same species of cyclopoids, new or rare for Europe, were found in Crimean ponds where there is no human agency that could lead to introductions of alien species. Long-distance transportation by birds, probably, is the more plausible explanation for their appearance in Lugansk. These alien species were found in newly formed water bodies without stable communities, which may serve as a jumping-off place for further distribution of East Asian cyclopid copepods across Europe. [ABSTRACT FROM AUTHOR]

Artemia (Anostraca) is among the most primitive and ancient groups of crustaceans. Artemia spp. play a dominant role in the ecosystems of hypersaline waters, and often they are the only animals in these extreme biotopes. Most ethological studies on Artemia have been conducted on nauplii and metanauplii. We made ethological observations on Artemia under laboratory conditions and in the natural waters of Crimea, where we studied growth and ontogenetic changes of swimming behavior. Growth occurred during the first 50 days up to a size of 9.5–10.5 mm, after which time the size did not increase (some females lived up to 6.5 months). A strong positive relation was found between maximal speed and individual length, which varied between 0.4 and 10.5 mm; it may be approximated by the power equation: V max = 1.205· K 0.820 , where V max is the maximal speed of Artemia (in mm s −1 ) of the length K (in mm). There is no similar relation between average speed and length of Artemia . The average speed of adults was 40–60% lower in environments with microalgae compared to media without food. The duration of the “riding position” for mating pairs of Artemia urmiana in our experiments varied from 10 to 27 days. In lakes we observed different Artemia aggregations varying in size and form. We conclude that the swimming behavior of Artemia is quite complex and diverse, and develops during ontogeny. [ABSTRACT FROM AUTHOR]

Inter-species variability in morphological traits creates a need to know the range of variability of characteristics in the species for taxonomic and ecological tasks. Copepoda Arctodiaptomus salinus, which inhabits water bodies across Eurasia and North Africa, plays a dominant role in plankton of different water bodies-from fresh to hypersaline. This work assesses the intra- and inter-population morphometric variability of A. salinus in the Mediterranean-Black Sea region and discusses some observed regularities. The variability of linear body parameters and proportions was studied. The impacts of salinity, temperature, and population density on morphological characteristics and their variability can manifest themselves in different ways at the intra- and inter-population levels. A significant effect of salinity, pH and temperature on the body proportions was not found. Their intra-population variability is dependent on temperature and salinity. Sexual dimorphism of A. salinus manifests in different linear parameters, proportions, and their variability. There were no effects of temperature, pH and salinity on the female/male parameter ratio. There were significant differences in the body proportions of males and females in different populations. The influence of temperature, salinity, and population density can be attributed to 80%-90% of intra-population variability of A. salinus. However, these factors can explain less than 40% of inter-population differences. Significant differences in the body proportions of males and females from different populations may suggest that some local populations of A. salinus in the Mediterranean-Black Sea region are in the initial stages of differentiation.

Arctodiaptomus salinus inhabits water bodies across Eurasia and North Africa. Based on our own data and that from the literature, we analyzed the influences of several factors on the intra- and inter-population variability of this species. A strong negative linear correlation between temperature and average body size in the Crimean and African populations was found, in which the parameters might be influenced by salinity. Meanwhile, a significant negative correlation between female body size and the altitude of habitats was found by comparing body size in populations from different regions. Individuals from environments with highly varying abiotic parameters, e.g. temporary reservoirs, had a larger body size than individuals from permanent water bodies. The changes in average body mass in populations were at 11.4 times, whereas, those in individual metabolic activities were at 6.2 times. Moreover, two size groups of A. salinus in the Crimean and the Siberian lakes were observed. The ratio of female length to male length fluctuated between 1.02 and 1.30. The average size of A. salinus in populations and its variations were determined by both genetic and environmental factors. However, the parities of these factors were unequal in either spatial or temporal scales.