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Succession of the ecosystems of the Aral Sea during its transition from oligohaline to polyhaline water body
Abstract
During 22 field trips from 1990 to 2002 (mainly the western basin of the Large Aral) data on salinity, phytoplankton, zooplankton, zoobenthos and fish fauna have been collected. In 2002, the salinity of the western basin reached 75 ppt, while that in the eastern basin, 150 ppt. In 1999–2002, 159 species of planktonic algae have been recorded. This is approximately twice as low as recorded before. The diversity of Cyanophyta, Pyrrhophyta and Chlorophyta in particular has dropped in the past few years. As before, currently Bacillariophyta is the most diverse plankton. However, the composition of dominants has changed. Once previously dominant species, Actinocyclus ehrenbergii, vanished from the plankton of the Aral Sea and was replaced by such diatoms as Amphora coffeaformis, A. coffeaformis var. acutiuscula and Synedra tabulata var. parva.
... (Cyclotella striata and Cyclotella stylorum) are planktonic brackish species. Prior studies have elucidated the potential of Cyclotella spp. as a salinity proxy, due to its discernible negative associations with both salinity and water depth 19,52,53 . Notably, Cyclotella spp. ...
... However, no significant correlation (r = 0.01, p > 0.05) was observed between its abundance and bottom salinity. Actinocyclus ehrenbergii and Actinoptychus senarius are nearshore benthic marine species with high abundance in low-salinity waters 32,53,61 . They can serve as proxies for salinity and sea level 53,61 . ...
... Actinocyclus ehrenbergii and Actinoptychus senarius are nearshore benthic marine species with high abundance in low-salinity waters 32,53,61 . They can serve as proxies for salinity and sea level 53,61 . Our results indicate that the abundances of both Actinoptychus senarius and Actinocyclus ehrenbergii decrease with increasing water depth and salinity in the Yangtze Estuary ( Supplementary Figs. ...
Many large estuaries are threatened by intensifying hypoxia. However, due to the limited duration of available observations, uncertainties persist regarding the level of contemporary hypoxia intensity in a longer-term context and the relative contributions of climate versus human factors. Here we present sediment records for the hypoxia intensity and associated environmental parameters in the Yangtze Estuary over the past three centuries. The results show that the hypoxia intensity has been increasing during the last half century due to anthropogenic eutrophication, but the current hypoxia condition is not as severe as some preindustrial periods due to weaker stratification in the water column. Our findings suggest that if anthropogenic and climatic forcing coincide in the foreseeable future, the hypoxia intensity of the Yangtze Estuary may reach unprecedented levels.
... The elevated salinity, whether in the water bodies or exposed lakebed, has had profound adverse effects on the local region. These effects caused substantial losses in fisheries, hindered vegetation growth, reduced crop production, and pose a serious threat to human health (Aladin and Williams, 1993;Mirabdullayev et al., 2004;Izhitskiy et al., 2016). Literatures often report on physical changes in the Aral Sea, such as fluctuations in water level, surface area, and volume (Singh et al., 2012;Shi et al., 2014;Singh et al., 2018;Sun and Ma, 2019;Yang et al., 2020;Tao et al., 2020), as well as hydrological variations, including lake evaporation, inflow, and water balance. ...
... Salinity data before 2002 are from Mirabdullayev et al. (2004). Data spanning from 2002 to 2019 originate from studies conducted by the Shirshov Institute of Oceanology of the Russian Academy of Sciences, in conjunction with institutions in Russia, Uzbekistan and Kazakhstan. ...
... Before 2002 (Mirabdullayev et al., 2004(Mirabdullayev et al., ) 2002 NAS, WAS (A2), WAS (Chernyshev Bay), Tshchebas (Friedrich and Oberhänsli, 2004;Zavialov et al., 2003) 2003/10 WAS (A2) (Zavialov et al., 2009) Table 3 Selection of equations for monthly evaporation calculation (in mm month − 1 ). ...
... So, sharp decrease of taxonomic diversity of bottom fauna of the Aral Sea during its salinization corresponds to the decrease of diversity of phytoplankton [10,12,16], zooplankton [1,[10][11][12][13] and fish [1,10,12]. ...
... So, sharp decrease of taxonomic diversity of bottom fauna of the Aral Sea during its salinization corresponds to the decrease of diversity of phytoplankton [10,12,16], zooplankton [1,[10][11][12][13] and fish [1,10,12]. ...
... So, sharp decrease of taxonomic diversity of bottom fauna of the Aral Sea during its salinization corresponds to the decrease of diversity of phytoplankton [10,12,16], zooplankton [1,[10][11][12][13] and fish [1,10,12]. ...
The changes in species composition and quantitative development of macrozoo-
benthos of the Aral Sea during the last 100 years have been considered. It was shown that in 1960s the diversity of macrozoobenthos increased by 22 % due to scheduled and accidental introductions. Later as a result of progressing salinization of the waterbody the number of species of bottom in-vertebrates steadily decreased and since 2004 acrozoobenthos of the Large Aral Sea is represent-
ed by the only species – larvae of chironomid Baeotendipes cf. noctivaga.
... They have seriously restricted the social development and stability of countries within arid regions. The "Aral Sea Crisis" is the most prominent environmental problems in Central Asia [4][5][6][7]. Excessive and unreasonable development and water uses in the Aral Sea area have resulted in a large amount of industrial and domestic wastewater, pesticides, chemical fertilizers, saline and alkaline water entering the Aral Sea, with residual irrigation water and agricultural discharges also becoming important sources of pollution [4][5][6][7][8]. ...
... The "Aral Sea Crisis" is the most prominent environmental problems in Central Asia [4][5][6][7]. Excessive and unreasonable development and water uses in the Aral Sea area have resulted in a large amount of industrial and domestic wastewater, pesticides, chemical fertilizers, saline and alkaline water entering the Aral Sea, with residual irrigation water and agricultural discharges also becoming important sources of pollution [4][5][6][7][8]. ...
... The current maximum salinity of the South Aral Sea is estimated to be 200 g/L [41]. Field surveys in South Aral Sea conducted between 1990 and 2002 found that many species of phytoplankton (216 species), zooplankton (38 species) and benthic fauna (57 species) had disappeared, and only two of the original 20 fish species were observed [6]. ...
The Aral Sea has received worldwide attention for the deterioration of its biological and chemical status. The accumulation of potentially toxic elements (PTEs) in the lake sediments reflects changes in the surrounding watershed and represents a potential hazard for the lake ecosystem. In conjunction with existing environmental records from the Aral Sea basin, sedimentary records of PTEs in North Aral Sea covering a short time scale, anno Domini (AD) 1950–2018, were used to reveal historical changes in PTE concentrations and potential risks to lake functioning. The results suggested that the levels of PTEs in lake sediments from North Aral Sea changed abruptly around 1970 AD, which is concurrent with the intensification of human activities within the basin. After 1970 AD, with the exception of As, which remained at unpolluted-to-moderately polluted levels, the geo-accumulation indices of the remaining PTEs studied (V, Cr, Zn, Co, Pb, Ni, Cu and Cd) inferred a moderately polluted status. Before 1970 AD, the total ecological risk was low, but since 1970, the total ecological risk index has exceeded 150, indicating moderate risk. Historical changes in PTE levels of lake sediments from North Aral Sea and their potential ecological risks are reported for the first time. The conclusions provide an important reference for the protection of lake ecosystems and will provide data for regional/global comparisons of environmental change during the Anthropocene.
... В этот же период исследования на Аральском море вели ученые из Казахстана (КазНИИРХ, Казахский государственный университет, Институт зоологии АН Казахстана) и Узбекистана. С 2003 г. к исследованиям на Большом Арале подключился Институт океанологии РАН, сотрудниками которого, помимо большого объема данных по гидрографии и гидрологии, были собраны новые материалы по его фауне (Стуге, 2002;Завьялов и др., 2006Mirabdullayev et al., 2004Mirabdullayev et al., , 2007Zavialov et al., 2009;Mokievsky, 2009;Arashkevich et al., 2009;Mokievsky, Miliutina, 2011). Глава 2. ...
... В настоящее время сохраняется в фауне Аральского моря, включая Большой Арал (Стуге, 2002;Mirabdullayev et al., 2004;Mokievsky, Miljutina, 2011), где в настоящее время это единственный достоверно известный вид Harpacticoida. ...
... Соленостный толерантный диапазон взрослых червейот пресной воды до 70‰ (Oglesby, 1970;Филиппов, 1995). У личинок его верхняя граница несколько ниже, возможно, 65‰ (Mirabdullayev et al., 2004). Осморегуляторные способностиконфогиперосмотик (Smith, 1970) I порядка (рис. ...
Монография посвящена фауне свободноживущих беспозвоночных Аральского моря и ее изменениям, которые происходили на протяжении второй половины XX века и в начале XXI века. В книге также освещена история изучения этого соленого континентального водоема и его фауны, дан его физико-географический очерк. Рассматриваются последствия как намеренного, так и случайного вселения человеком прежде отсутствовавших в море видов животных. Подробно обсуждаются изменения в фауне свободноживущих беспозвоночных Аральского моря, связанные с изменением его солености. Сделан прогноз о будущем этой фауны как для Малого Аральского моря, так и для остаточных водоемов Большого Аральского моря.
Книга предназначена для зоологов, гидробиологов и студентов соответствующих специальностей.
... Artemia parthenogenetica was first found in the Large Aral Sea in 1998 [19]. Since 2002, the hypersaline species, A. parthenogenetica, has absolutely dominated the zooplankton community making up 99% of the total biomass [20,21]. ...
... In the Large Aral Sea the Artemia population appeared in noticeable numbers only in 2000 but earlier a few individuals were reported in the shallow lagoons and from separated salt ponds near the sea [19,20,32]. The appearance of Artemia in the Aral coincided with the increase in salinity up to 63 ppt. ...
... The publication [20], published recently and devoted to the biota of the Large Aral Sea, includes data about benthic communities. On the basis of data from 22 expeditions (from 1990 till 2002), the authors observed considerable changes in diversity over the last few decades in the Western and Eastern basins. ...
During the last five decades the Aral Sea has been undergoing dramatic changes. Because of river runoff cessation and subsequent decrease in water body volume, mineralisation in the western Large Aral increased from 10 ppt in 1960 to 116 ppt in 2008. Concurrently, crucial changes have been occurring in the Aral ecosystem manifested by the disappearance of most native species and a significant decline in biodiversity. The objective of this chapter is to consider the main results on species composition and distribution of benthic and pelagic organisms obtained between 2002 and 2008 along with the historical data on biodiversity of the Aral Sea.
... The contemporary eastern and western Aral basins are hypersaline water bodies with total elimination of fish and invertebrate species of fresh, brackish water, or marine origin (Williams and Aladin, 2006). Changes in the biotic composition of the Aral Sea have been monitored in detail since the 1960s, and have been extensively documented in Russian-language journals (see overview in Mirabdullayev et al., 2004). Since the 1990s multiple international scientific studies have described the Aral ecosystems in their transition from an oligohaline into a hypersaline water body, including the gradual colonization of the open part of the lake by a parthenogenetic Artemia population (Aladin and Potts, 1992;Aladin et al., 1998;Andreev et al., 1992a,b;Filippov, 1997;Filippov and Komendantov, 1996;Friedricht and Oberhansli, 2005;Mirabdullayev et al., 2004). ...
... Changes in the biotic composition of the Aral Sea have been monitored in detail since the 1960s, and have been extensively documented in Russian-language journals (see overview in Mirabdullayev et al., 2004). Since the 1990s multiple international scientific studies have described the Aral ecosystems in their transition from an oligohaline into a hypersaline water body, including the gradual colonization of the open part of the lake by a parthenogenetic Artemia population (Aladin and Potts, 1992;Aladin et al., 1998;Andreev et al., 1992a,b;Filippov, 1997;Filippov and Komendantov, 1996;Friedricht and Oberhansli, 2005;Mirabdullayev et al., 2004). ...
... Local records collected over a two decade period from the 1980s through the 1990s reported the existence of a local parthenogenetic Artemia population in coastal shallow water bodies adjacent to the former Aral Sea bed, and in small lakes and pools on the nearby Ustyurt Plateau, west of the Aral Sea (Mirabdullayev et al., 2004). At the end of the 1990s Artemia presence was occasionally recorded in the Aral Sea itself near the NE coast of the former Vozrozhdeniya Island (now a peninsula; Joldasova et al., 1999). ...
The objective of this study was to provide information on the developing parthenogenetic Artemia population in the Uzbek part of the Aral Sea, and to assess its potential for commercial exploitation. A sampling campaign was designed for abiotic factors (temperature, salinity, transparency) and Artemia population parameters at least once monthly in the period March–October of the years 2005–2007.By 2007 salinity in both basins had increased to values above 100gl−1. Moreover, by 2007, desiccation had rendered the eastern Aral basin practically inaccessible for sampling or cyst harvesting. The volume of the western basin remained considerable, given its depth, with a relatively accessible shoreline. Average Artemia population parameters (e.g. adult abundance
... [12] We can compute the total salt content using values for the volume of the sea and available salinity data [Mirabdullayev et al., 2004]. A measurement error of 3.9cm for the T/P data would result in an error in the basin volume of $1.2 km 3 . ...
... [13] The estimations of basin mean salinity suffer from bad temporal and spatial coverage of observations, in particular in the last decade. The most complete (in time) data of Mirabdullayev et al. [2004] does not provide enough spatial coverage to accurately reconstruct the basin mean salinity. By 2001 this data set gives S 2001 $ 65 psu while the observations of Zavialov et al. [2003] and Friedrich and Oberhansli [2004] using vertical profiling give S 2001 $ 90 psu. ...
... The upper two curves correspond to estimates produced by interpolating salinity between 1992 and 2000 using S 2001 = 85 psu and S 2001 = 75 psu, correspondingly. Diamonds (the values after 1996 are for the Western basin) correspond to data ofMirabdullayev et al. [2004]. ...
We demonstrate in this paper that satellite altimeter data resolve the drop in the Aral Sea level during 1993-2000 of about 0.6 m per year resulting in a change of surface area from 35000 to 22000 km2 and volume from 270 to 130 km3. The sudden drop in the sea level of the Northern basin on 04.21.1999 resulting from dam break-up is also clearly resolved. The temporal and spatial variability of sea level reveals response patterns which are characteristic for friction dominated shallow sea dynamics. The combination of salinity and sea-level data enables to identify the major events of environmental transition, which are associated with the temporal variability in the total salt content: (1) a peak in 1993-1994, and (2) an increasing trend in the last decade. These events are indicative of an increase in the discharge of ground water, but could also reveal overestimated salinity estimates from recent observations.
... In 1998, the dominant zooplankton species had disappeared, including Calanipeda aquaedulcis and Halicyclops rotundipes aralensis. Most truly marine harpacticoids also disappeared, and only three aboriginal and high salinity (> 100 ppt tolerant species may now remain: the presence of Cletocamptus retrogressus is documented, but there is no information on C. confluens and Nitocra lacustris (Mirabdullayev et al. 2004;Mokievsky and Miljutina 2011). The ostracod Cyprinotus salinus disappeared before 2002, while the very salinity tolerant Cyprideis torosa remained in the western part in 2005 (Zavialov 2012). ...
... During hypersalinization there were temporary species invasions. The cladoceran Moina mongolica reappeared in 1996, but was gone again by 2002 (Mirabdullayev et al. 2004;Aladin and Plotnikov 2008). The halophilic copepod Apocyclops dengizicus appeared in the western Great Aral in 2004 and seems to have become established (Mirabdullayev et al. 2007). ...
The regression and salinization of the Aral Sea, largely caused by water diversion for irrigation, is among the most severe ecological disasters of the 20th century, and has had severe health and economic consequences for the local population. Introductions of alien species to enhance commercial fisheries before the regression had already impacted the ecology of this system. Crustaceans made up about one-quarter of the original metazoan species and constituted the principal food for native and introduced fish. From 1960 on, crustaceans were recorded at numerous fixed sampling stations, including thanatocoenoses (dead animals from sediment cores). We use this previously unpublished information to document changes in species abundance and discuss their causes in the context of species interactions and changes to physical and chemical parameters. Competition from alien crustaceans led to declines in or even extinction of some native species, but eventually severe salinization became the main detriment, and resulted in the complete collapse of commercial fisheries. This seriously hurt a critical trade, which provided the principal protein source for the local population. We document how comparatively modest conservation efforts enabled the northern Small Aral Sea to partially recover and commercial fishing to resume.
... в гипергалинный водоем привело к новым и очень значительным изменениям в фауне этой части Арала. В результате исчезновения большинства сохранявшихся видов сократилось и так уже низкое видовое разнообразие (Mirabdullayev et al. 2004 ...
... При этом естественным путем вселился ряд ранее отсутствовавших видов беспозвоночных, характерных для фауны гипергалинных водоемов. Появились галофильные инфузории Frontonia marina Fabre-Domergue и Fabrea salina Henneguy, жаброногий рачок Artemia parthenogenetica Bowen et Sterling, ставший доминирующим в зоопланктоне, копепода Apocyclops dengizicus (Lepeshkin), ракушковый рачок Eucypris mareotica (Fischer) и личинки хирономиды Baeotendipes noctivaga (Kieffer)(Mirabdullayev et al. 2004(Mirabdullayev et al. , 2007 Аладин и Плотников [Aladin and Plotnikov] 2008; Завьялов и др.[Zavialov et al.] 2006[Zavialov et al.] , 2012Mokievsky and Miljutina 2011; Жолдасова и др. [Zholdasova et al.] 1999 Жолдасова и др. ...
The Aral Sea, a large saline terminal lake in Central Asia, since 1960 dries quickly, and by September 2009 it had separated into four residual water reservoirs. The maximum water level decline exceeded 26 m, the surface area has decreased by 88% and water volume by 92%. Salinity increased by more than 20-fold. Prior to the modern recession, the Aral Sea experienced a number of water level declines and subsequent recoveries over the last 10 millennia. The main causative factor until the 1960s was the periodic westward diversion of the Amu Dar’ya towards the Caspian Sea by both natural and human forces. Modern regression is the result of irrigation development and has caused many severe problems. To restore the Aral Sea to its present state would be very difficult, if not impossible, in the foreseeable future. However, a partial restoration of its separate parts is possible. Completed in 2005 project has allowed to raise the level of the Small (northern) Aral Sea and further reduce its salinity. In the paper are discussed plans for further rehabilitation of the Small Sea and possible restoration of some parts of the Large (southern) Aral Sea.
... в гипергалинный водоем привело к новым и очень значительным изменениям в фауне этой части Арала. В результате исчезновения большинства сохранявшихся видов сократилось и так уже низкое видовое разнообразие (Mirabdullayev et al. 2004 ...
... При этом естественным путем вселился ряд ранее отсутствовавших видов беспозвоночных, характерных для фауны гипергалинных водоемов. Появились галофильные инфузории Frontonia marina Fabre-Domergue и Fabrea salina Henneguy, жаброногий рачок Artemia parthenogenetica Bowen et Sterling, ставший доминирующим в зоопланктоне, копепода Apocyclops dengizicus (Lepeshkin), ракушковый рачок Eucypris mareotica (Fischer) и личинки хирономиды Baeotendipes noctivaga (Kieffer)(Mirabdullayev et al. 2004(Mirabdullayev et al. , 2007 Аладин и Плотников [Aladin and Plotnikov] 2008; Завьялов и др.[Zavialov et al.] 2006[Zavialov et al.] , 2012Mokievsky and Miljutina 2011; Жолдасова и др. [Zholdasova et al.] 1999 Жолдасова и др. ...
The Aral Sea, a large saline terminal lake in Central Asia, since 1960 dries quickly, and by September 2009 it had separated into four residual water reservoirs. The maximum water level decline exceeded 26 m, the surface area has decreased by 88% and water volume by 92%. Salinity increased by more than 20-fold. Prior to the modern recession, the Aral Sea experienced a number of water level declines and subsequent recoveries over the last 10 millennia. The main causative factor until the 1960s was the periodic westward diversion of the Amu Dar’ya towards the Caspian Sea by both natural and human forces. Modern regression is the result of irrigation development and has caused many severe problems. To restore the Aral Sea to its present state would be very difficult, if not impossible, in the foreseeable future. However, a partial restoration of its separate parts is possible. Completed in 2005 project has allowed to raise the level of the Small (northern) Aral Sea and further reduce its salinity. In the paper are discussed plans for further rehabilitation of the Small Sea and possible restoration of some parts of the Large (southern) Aral Sea.
... Per T. tenera la prima, nonché tuttora -per quanto ci risulta -unica segnalazione relativa ai mari italiani si riferisce all'isola di Panarea nelle Eolie (ColAngelo et al., 2001) 2012), nonché di località (Spagna, Portogallo) della costa orientale dell'Atlantico (frisCh et al., 2006; AlBAinA et al., 2009; BoxshAll and defAye, 2009) e dell'area del Baltico (U.S. EPA, 2008). In ambito extraeuropeo le segnalazioni riguardano anche il marocco (mirABdullAyev et al., 2004) e il lago d'Aral in Kazachstan dove, introdotta negli anni '60, C. aquaedulcis divenne una delle specie dominanti dello zooplancton (mirABdullAyev et al., 2004), fino alla sua scomparsa nel 1997 (BAker et al., 2015). Almeno per una località (estuario del Bilbao in Portogallo), si ipotizza un insediamento dovuto a trasporto passivo in acque di zavorra di natanti (AlBAinA et al., 2009). ...
... Per T. tenera la prima, nonché tuttora -per quanto ci risulta -unica segnalazione relativa ai mari italiani si riferisce all'isola di Panarea nelle Eolie (ColAngelo et al., 2001) 2012), nonché di località (Spagna, Portogallo) della costa orientale dell'Atlantico (frisCh et al., 2006; AlBAinA et al., 2009; BoxshAll and defAye, 2009) e dell'area del Baltico (U.S. EPA, 2008). In ambito extraeuropeo le segnalazioni riguardano anche il marocco (mirABdullAyev et al., 2004) e il lago d'Aral in Kazachstan dove, introdotta negli anni '60, C. aquaedulcis divenne una delle specie dominanti dello zooplancton (mirABdullAyev et al., 2004), fino alla sua scomparsa nel 1997 (BAker et al., 2015). Almeno per una località (estuario del Bilbao in Portogallo), si ipotizza un insediamento dovuto a trasporto passivo in acque di zavorra di natanti (AlBAinA et al., 2009). ...
The artificial pond “Sette Nani” is a small, brackish lagoon on the Ionian coast of Apulia (southern Italy), about 50 km SE of Taranto. Its environmental (temperature, salinity, pH) and faunal characteristics were investigated (Ariani and Wittmann, 2014) in the frame of a study on ecology and breeding biology of the Mysida species Diamysis cymodoceae Wittmann and Ariani, 2012. These investigations revealed the presence of two copepod species: (1) the harpacticoid Tisbe tenera (G. O. Sars, 1905), and (2) the calanoid Calanipeda aquaedulcis Kritchagin, 1873, first recorded here for the Ionian Sea and for the Ionian coast of the Italian peninsula, respectively. C. aquaedulcis is an invasive, essentially brackish-water element first described from the Ponto-Caspian basin and subsequently reported from several localities along
the Mediterranean and the Eastern Atlantic coasts. Certain samplings of the species showed a sex-ratio near 1.0, indicative of potential genetic sex-determination, thus suggesting that the population components were born in the pond and developed there without apparent sexual selection. A sudden bloom of C. aquaedulcis was noted in January to March 2015, in accordance with the typical winter to early-spring maximum in this species, in this case coinciding with the massive appearance of a filiform green alga which quickly covered large parts of rock substrata: in fact, most fixed copepods were found inside the algal network, which they may have used for avoidance of predation. A population regression down to almost disappearance occurred in May, however followed by a further growth in August: the latter events
may be explained in the light of the well-known production of resting eggs by C. aquaedulcis.
... The western basin is a trench with a steep bottom slope at the western side where the maximum depths still exceed 40 m, while the eastern basin is a relatively large but very shallow (less than 5 m deep) water body. The desiccation and salinization of the sea have led to desertification and degradation of the regional ecosystem, and had severe impact on the quality of life and health of the local population (Micklin, 1988;Létolle and Mainguet, 1993;Glazovsky, 1995a, b;Micklin and Williams, 1996;Glantz, 1999;Kostianoy and Wiseman, 2004;Mirabdullayev et al., 2004;Zavialov, 2005;Nezlin et al., 2005). ...
... Before the separation of the Small and Large Aral Seas in 1989 the salinity was 28-30 ppt. Salinity measurements in the Large Aral Sea are sparse and not well assessed, but it is known that salinity in the Large Aral Sea has reached in 2002 more than 80 g/l (Zavialov et al., 2003a,b) in the western part and around 100-120 g/l in the eastern part in 2001 (Mirabdullayev et al., 2004). This change in salinity resulted in the decrease of the freezing temperature down to about −5°C (Zavialov, 2005), but also in the lowering of temperature of maximal density, which, according to some data, even at 40-50 g/l becomes less than the freezing temperature (Ginzburg et al., 2003). ...
We discuss recent seasonal and interannual variations of ice cover and lake surface level in the Aral Sea from satellite data for 1992–2006. First, we provide an overview of the evolution of the Aral Sea's environmental conditions, hydrological and ice regime, existing observations and current state of the scientific research. Desiccation of the Aral Sea led to disappearance of the infrastructure in the coastal zone, including meteorological and sea level gauge stations. The current lack of reliable in-situ measurements and time series for sea level and ice cover parameters since mid-1980s can be partly overcome with radar altimeter and microwave satellite observations that provide reliable, frequent, regular and weather-independent data. In our study, we use radar altimeter data from TOPEX/Poseidon, Jason-1, ENVISAT and GFO satellites, as well as the Special Sensor Microwave/Imager (SSM/I) radiometer. An ice discrimination method, based on the synergy of active and passive data from the four altimetric missions and SSM/I, is proposed and applied to the entire satellite dataset to define the specific dates of ice events for 1992–2006. We then analyse the evolution of the sea level in the Large and Small Aral sea and Sarykamysh lake. For this purpose, we compare time series from several sources (Hydroweb, USDA Reservoir Database, Integrated Satellite Altimetry Data Base and others), perform an intercomparison of the available observations and discuss the reasons for potential differences. Using the data from the four altimetric retrackers for ENVISAT, we also estimate how the presence of ice could affect the altimeter range measures. We estimate the associated uncertainties and provide recommendations for adjusting sea level time series for altimeters where only ocean retracker (T/P, Jason-1, GFO) is present.
... Too high concentrations of a single major ion and groups of ions may adversely affect aquatic biocenosis [8,9]. Salinity, referring to the total concentration of dissolved inorganic ions (mostly Na + , K + , Ca 2+ , Mg 2+ , HCO 3 − , CO 3 2− , Cl − , and SO 4 2− [10]) in water, has been recognised as one of the most important parameters determining biodiversity in aquatic ecosystems, including phyto-and zooplankton, benthic macroinvertebrates, and fish [11][12][13][14][15][16]. It affects various levels of ecosystem organisation [14]. ...
Flow influences major ion concentrations in river water, therefore, it seems that it can differentiate ion concentrations in mountain rivers in different hydrological years. This study aimed to determine the impact of flow on the major ion concentrations in the Carpathian Raba River above and below the Dobczyce Reservoir (southern Poland) in hydrologically dry (HD), average (HA), and wet (HW) years (period April–October) in the period 2010–2017. In the river above the reservoir, the flow negatively affected the concentrations of most major ions under all hydrological conditions, which resulted in their significant differences between (1) the studied hydrological years (except for SO42−)–higher in the HD years than in the HA or HW years–and (2) seasons–higher Mg2+, Na+, K+, Cl−, and SO42− concentrations (mainly point sources of pollution) were identified in summer or autumn than in spring in the HD and HA years. The dam reservoir strongly modified the ion concentrations in the downstream river. It significantly decreased all major ion concentrations only in the HD years, when they were high in the upstream river, and Ca2+, Mg2+, or HCO3− concentrations in all the studied hydrological years. There, the ion concentrations were not related to the flow that resulted in their insignificant differences between the studied hydrological years (with the exception of HCO3−, Ca2+, and Cl−) and different seasonal changes to those in the river above the dam. The obtained results allow for predicting conditions favouring an increase in the salinity of mountain river waters; therefore, they are important for appropriate management and water use opportunities.
... With continuous water level decrease, the Large Aral became hypersaline with specific fauna, and among them, the brine shrimp (Artemia parthenogenetica) became dominant in the zooplankton population (Aladin & Plotnikov, 2008). According to Mirabdullayev et al. (2004), since 2000, Artemia has constituted 99% of the zooplankton biomass of the Aral Sea. As a consequence, Artemia faecal pellets are a dominant constituent of the recent biochemical sediment in the Aral Sea. ...
A 25 m long sediment core from hypersaline Urmia Lake (north‐west Iran) was studied for the Late Quaternary depositional history and palaeoclimate variations using the abundance and compositional characteristics of Artemia fecal pellets. Sediment analysis is supported by scanning electron microscopy – energy dispersive X‐ray spectroscopy, organic and inorganic carbon contents measurements, and stable isotopes (δ ¹³ C and δ ¹⁸ O) from fecal pellet carbonates. The imprecise chronology of the core back to 50 kyr BP is supported by ten radiocarbon ages from fecal pellets and bulk sediments. The palaeoenvironmental record is subdivided into four periods: (i) During much of Marine Isotope Stage 3, a period of lake level lowering is characterized by a decreasing amount of fecal pellets, and an increasing amount of coated grains, sulphate minerals and reworked shell fragments. (ii) During late Marine Isotope Stage 3 and early Marine Isotope Stage 2 a lake level lowstand and a lake floor exposure is interpreted based on the relatively low abundance of pellets, which are multicoloured and appear together with volcanic lithics and rounded sulphate minerals. (iii) During late Marine Isotope Stage 2 the record is devoid of pellets but dominated by large sulphate crystals suggesting a prolonged low lake level. (iv) During Marine Isotope Stage 1 a relative lake level highstand is rapidly established with sediments that are highly abundant in fresh pellets. The modern lake level lowstand is represented by a salt crust. The δ ¹³ C and δ ¹⁸ O records measured from fecal pellet carbonates suggest a link with the precipitation versus evaporation balance in the lake over time. From bottom to top the linear trend towards more negative delta values illustrates the increasing amount of precipitation arriving at the lake from the Late Pleistocene to the Holocene. Two prominent isotope minima during the Late Pleistocene and one prominent minimum in the early Holocene mark relative high lake levels, which can also be linked to Lake Van in Turkey.
... This brackish and estuarine calanoid copepod species are indigenous to the Ponto-Caspian basin and have extended their distribution over the Mediterranean coastal areas of Europe and the Azov Sea (US EPA, 2008). It has not only grown significantly outside of its native region, but it may also quickly establish a major population following its introduction to a new location (Barroeta et al., 2020;Lazareva, 2018) as the most abundant species in zooplankton populations (Albaina et al., 2009;Mirabdullayev et al., 2004;Taglialatela et al., 2014). The genus Calanipeda is an osmoconformer; it can adapt to a diverse spectrum of salinities (Svetlichny et al., 2012a), and even though it is eurythermal (3-30 • C), it typically prefers a colder environment (Brugnano et al., 2011;Frisch et al., 2006). ...
Copepods are an important part of the marine food web because of their high biomass productivity and nutrient turnover rate compared to other zooplankton in the marine ecosystem. Despite their great ecological role in the ocean, there is only limited information available on the consequences of ocean acidification (OA) induced by the future increase in CO2 on the planet. More specifically, there is almost no information about the impact of OA on the European copepod Calanipeda aquaedulcis Kritschagin, 1873. Therefore, the present investigation hypothesized that OA would not produce negative multigenerational effects on the survival and reproductive performance of this copepod species. Here we assessed, the multigenerational (F1 and F2) effect of OA on eight important reproductive traits (maturity, prosome length, fertility, egg release, hatching success, survival rate, reproductive performance, and the total number of adults per generation). For this study, C. aquaedulcis were collected from the Guadalquivir River (southwest of Spain) and were exposed to four different pH gradients (pH 8.1 as control and pH 7.5, 7.0, 6.5 as acidified conditions) to mimic the future seawater acidification scenarios. The survival rate from nauplius to adult, C. aquaedulcis was significantly reduced by pHs and across generations. Besides, results also indicated that there were marked effects on fertility, reflected by a significantly lower number of eggs per female in each generation. Similarly, hatching success also showed a decreasing pattern towards low pH, and importantly, F1 females had lower hatching success than F0 females. While a beneficial parental effect was detected in the offspring in response to OA, it was insufficient to offset the negative effects caused by it. The findings presented here appear to have ecological significance, as decreasing the reproductive performance of copepods may have a negative impact on the marine food web, as ichthyofaunal feeding and growth are heavily reliant on this component of the food web.
... In terms of water mineralization, in 2015 the deepest central part of the pit lake had two distinct layers: the surface layer (0-5 m) was well oxygenated with mineralization of 50-134 g dm −3 , and the underlying layer (up to a depth of 85 m) was poorly oxygenated with a mineralization 179-420 g dm −3 (Zurek et al. 2018). It is known that the salinity is the main parameter governing the biological biodiversity (Mirabdullayev et al. 2004;Zinchenko et al. 2019). The high levels of water mineralization of the Dombrovska Responsible editor: Philippe Garrigues * Ewa Szarek-Gwiazda szarek@iop.krakow.pl ...
This study focuses on the Dombrovska pit lake, near the city of Kalush in Ukraine, which is a former potassium salt mine filled with brine and freshwater. The water level is still increasing and as a result the salinity is decreasing. We analyzed the benthic fauna communities and the genome instability by assessing the rearrangements in the polytene chromosomes of Chironomus salinarius and the physicochemical parameters of the near-bottom water (pH, conductivity, mineralization, major ions, NO3−, NH4+, metals Cd, Pb, Cu, Mn, and Fe) and sediment (pH, organic matter and metals Cd, Pb, Cu, Zn, Mn, and Fe) at four sites. The water mineralization ranged from 17.3 to 26.2 g dm−3 which are classified as mesohaline and polyhaline waters, respectively. The biodiversity of the benthic fauna was low, and the dominant species was C. salinarius. The density of C. salinarius varied spatially and changed from 637 ind./m2 at a depth of 5 m to 8167 ind./m2 at a depth of 2.5 m. The genome instability was analyzed by examining the structural and functional changes in the salivary gland chromosomes of C. salinarius. The exposure of C. salinarius damaged the chromosomes and the activities of key structures, such as the Balbiani ring and nucleolar organizer, were partially or completely suppressed.
... In inland water bodies that have shrunken most drastically, the associated water quality implications have devastated aquatic ecosystems, as in the case of the Aral Sea (Aladin & Plotnikov, 1993), in which an order of magnitude increase in salinity decimated freshwater and brackish fish species along with the fishing industry (Hampton et al., 2018). Almost all native aquatic animals were extirpated from the Aral Sea due to rising salinity (Mirabdullayev et al., 2004). While the Aral Sea disaster presents an extreme endmember with respect to ecological impacts of inland water body loss, even small areal shrinkage of lakes profoundly affects their ecological dynamics (Jeppesen et al., 2015). ...
Abstract Lakes—quintessential features of Earth's surface prized from perspectives of water security, aquatic ecosystems, and recreation alike—are shrinking in water‐limited regions of all of Earth's inhabited continents. Here we assessed Landsat‐derived long‐term decrease in global lake area relative to historical lake extent aiming to determine the role of recent Anthropocene levels of irrigated agriculture in the global phenomenon of lake desiccation. As of 2015, 11% (1.8 · 105km2) of global lake area has already been lost, primarily due to increased water consumption in support of irrigated agriculture in endorheic basins within water‐limited regions. However, current levels of irrigated agriculture portend substantial additional shrinkage of global lakes before reaching new equilibria with present‐day inflows, with an additional 60–130% increase in endorheic lake loss anticipated. The time required for shrinking lakes to attain new equilibria ranges from decades to centuries depending on lake hyposometry. Even a small decrease in lake area can portend lake transition from exorheic to endorheic and dramatic reductions in water quality. Thus, lake area changes severely understate the perilous condition of global lakes. The watershed area contributing to shrinking (endorheic and exorheic) lakes accounts for 18% of Earth's land area, far too large for the irrigated agriculture therein to be transferred elsewhere in order to save these lakes, though continued developments in the efficiency of water consumption in agriculture and urban areas can save significant quantities of water. This suggests that global lake shrinkage may be a harbinger signaling mankind having exceeded Earth's sustainable carrying capacity.
... Hundreds of thousands of people have been displaced, and exposure to toxic metals and agrochemicals of associated with bottom sediments has resulted in increased deaths and chronic disease (Kaneko et al. 2003). Ecosystems in and around the lake's pelagic region, Delta marshes, and fringing forests were decimated, and have experienced large-scale declines in biodiversity (e.g., Mirabdullayev et al. 2004;Micklin 2007). As the lake became hypersaline, most freshwater and brackish species declined, and the fishing industry died out in the 1980s. ...
Ancient lakes are among the best archivists of past environmental change, having experienced more than one full glacial cycle, a wide range of climatic conditions, tectonic events, and long association with human settlements. These lakes not only record long histories of environmental variation and human activity in their sediments, but also harbor very high levels of biodiversity and endemism. Yet, ancient lakes are faced with a familiar suite of anthropogenic threats, which may degrade the unusual properties that make them especially valuable to science and society. In all ancient lakes for which data exist, significant warming of surface waters has occurred, with a broad range of consequences. Eutrophication threatens both native species assemblages and regional economies reliant on clean surface water, fisheries, and tourism. Where sewage contributes nutrients and heavy metals, one can anticipate the occurrence of less understood emerging contaminants, such as pharmaceuticals, personal care products, and microplastics that negatively affect lake biota and water quality. Human populations continue to increase in most of the ancient lakes’ watersheds, which will exacerbate these concerns. Further, human alterations of hydrology, including those produced through climate change, have altered lake levels. Co‐occurring with these impacts have been intentional and unintentional species introductions, altering biodiversity. Given that the distinctive character of each ancient lake is strongly linked to age, there may be few options to remediate losses of species or other ecosystem damage associated with modern ecological change, heightening the imperative for understanding these systems.
... Williams et al. (1990) proposed that when salinity is lower than 50 g L −1 , there is a negative correlation with zooplankton richness, but at higher salinities, diversity changes are minimal because few organisms can tolerate the osmotic stress (Hammer, 1986). These changes have been identified within the same lake for both hyposaline (Vignatti et al., 2012c) and hypersaline lakes (Mirabdullayev et al., 2004). The negative effect of salinity on zooplankton diversity has been also found in saline lakes of South America. ...
... Ostenfeld (1908) listed 10 taxa for historical records when the sea was at its greatest size. Orlova and Rusakova (1999) list eight taxa for northern Aral Sea in 2003, but Mirabdullayev et al. (2004) gave a range of 15 (1925) to 28 (1967-1974), decreasing to only three species by 2004 when the cyanophytes Oscillatoria woronichinii Anissimova, 1949 (a cosmopolitan halophile), and Anabaena bergii Ostenfeld, 1908(now Chrysosporum bergii (Ostenfeld, 1908 Zapomelová, Skácelová, Pumann, Kopp and Janecek, 2012, a brackish species) became dominant. This low number is the result of rapid dessication and salinity increase. ...
We present the first comprehensive taxonomic and environmental study of dinoflagellate cysts in 185 surface sediment samples from the Black Sea Corridor (BSC) which is a series of marine basins extending from the Aegean to the Aral Seas (including Marmara, Black, Azov and Caspian Seas). For decades, these low-salinity, semi-enclosed or endorheic basins have experienced large-scale changes because of intensive agriculture and industrialisation, with consequent eutrophication and increased algal blooms. The BSC atlas data provide a
baseline for improved understanding of linkages between surface water conditions and dinoflagellate cyst (dinocyst)
distribution, diversity and morphological variations. By cross-reference to dinocyst occurrences in sediment
cores with radiocarbon ages covering the past c. 11,700 years, the history of recent biodiversity changes
can be evaluated. The seabed cyst samples integrate seasonal and multi-year data which are not usually captured
by plankton samples, and the cyst composition can point to presence of previously unrecorded motile dinoflagellate
species in the BSC. Results show the presence of at least 71 dinocyst taxa of which 36% can be related
to motile stages recorded in the plankton. Comparison with sediment core records shows that five new taxa
appear to have entered or re-entered the region over the past century. Statistical analysis of the atlas data reveals
the presence of four ecological assemblages which are primarily correlated with seasonal and annual surface
water salinity and temperature; correlation with phosphate, nitrate and silicate nutrients, chlorophyll-a and
bottom water oxygen is less clear but may be important for some taxa. Biodiversity indices reveal strong west−
east biogeographical differences among the basins that reflect the different histories of Mediterranean versus
Ponto-Caspian connections. The atlas data provide a standardised taxonomy and regional database for interpreting
downcore cyst variations in terms of quantitative oceanographic changes. The atlas also provides a
baseline for monitoring further changes in the BSC dinocysts that may accompany the accelerating development
of the region.
... Salinity is often considered as one of the main environmental stress factors both in Prokaryota (Ambily Nath & Loka Bharathi, 2011) and Eukaryota (Parida & Das, 2005;Lauritano et al., 2012;Telesh et al., 2013). Salinity fluctuations alter significantly the biodiversity and functioning of an ecosystem (Mirabdullayev et al., 2004;Velasco et al., 2006;Balushkina et al., 2009;Abbaspour et al., 2012;Carrasco & Perissinotto, 2012). ...
The wide distribution of crustaceans from
freshwater through brackish into marine waters and
from salt marshes to terrestrial zones shows the
exceptional capacities of this animal group to cope
with salinity changes. Osmoregulation is the main
physiological mechanism that maintains the
hydromineral homeostasis of these animals. The
difference of osmoregulation capacities between an
osmoconformer and an osmoregulator species is
mainly explained by anisosmotic extracellular regulation
(AER) and/or isosmotic intracellular regulation
(IIR). This review will also discuss the particular
acquisition of specific osmoregulation capacities in
crustaceans from the first embryonic stages to the
adult. Several findings revealed that gills and antennal
glands are the primordial hydromineral regulation
tissues, and they present the same structure and
function in all crustaceans, except in shrimps. These
tissues contain ionocytes that harbor membrane pumps
implicated in ion regulation. Na?/K?-ATPase, the
major of these membrane proteins, acts upon rapid
ionic changes, usually in cooperation with several
other membrane pumps. Also some proteins, belonging
to the detoxification and antioxidant systems, seem
implicated in the regulation mechanisms after salinity
change. This review will resume and discuss the
current knowledge on salinity regulation in this large
and important animal group.
... Perhaps Karateren's baseline community mix of sensitive and halotolerant species was ultimately more tolerant of high drought-induced salinity. The three copepod (Cletocamptus retrogressus, Onychocamptus bengalensis and Schizopera aralensis) and one rotifer (Brachionus plicatilis) species observed in Karateren in fall 2001 were indeed tolerant of hypersaline conditions (Borutskii, 1952;Mirabdullayev and Ishida, 2002;Mirabdullayev et al., 2004;Morduchai-Boltovski, 1974) and present in the Karateren community leading up to the dry period. However, these species were also relatively common, and were also found in the other lakes leading up to the dry period, including the two fresh lakes B. Aydin and B. Sudochye (Appendix 1, electronic version only). ...
Effects of drought-induced salinity changes on aquatic communities are less studied in lentic than in lotic systems. We present changes in zooplankton assemblages from five arid lakes before, during, and after a supra-seasonal drying event in which lake inflow ceased in 2001. We catalogued zooplankton communities in fresh and saline lakes of the Sudochye wetland in Central Asia. During this record low flow period, salinity increased in the lakes. Zooplankton species richness was inversely correlated with salinity. Linear regression using species richness indicated that zooplankton communities in the two least saline lakes were strongly correlated with changes in salinity. Post-drought recovery of species richness suggested resilience to this perturbation. Both saline lakes' zooplankton communities had low correlation with changes in salinity, suggesting greater resistance than the freshwater communities. The fifth lake showed a hybrid response, beginning in the fresh range, but experiencing higher salinities than the other fresh lakes. In the fifth lake species-richness was similarly correlated to changes in salinity as compared to the saline lakes, correlation of % halotolerant species was intermediate between saline and fresh communities, and post-drought species richness was similar to the fresh lakes, which could indicate a “resilient” recovery of species richness.
... Moreover, Small et al. (2001) based their analysis on the data prior to the separation of the Big and Small Aral (when salinity was around 30 ppt) and did not take into account the very high and non-homogeneous recent increases of salinity of the Big Aral. Even if salinity measurements in the Big Aral Sea are sparse and not well assessed, it is known that by 2002 salinity reached over 80 ppt (Zavialov et al. 2003) in the western part and around 100 ppt to 120 ppt in the eastern part in 2001 (Mirabdullayev et al. 2004). Because the Big Aral is still drying, the salinity should still be increasing. ...
... Presently, with water salinity reaching 83-84‰, the marine fauna are also close to extinction: compare the 1960 fish catch in the Amu Darya delta (22,520 ton) to the 2000 catch (1,100 ton) (Ashirbekov et al., 2002). Out of 20 species of fish, only two still remain in the sea; also lost are 216 species of phytoplankton, 38 species of zooplankton and 57 species of zoobenthos (Mirabdullayev et al., 2004). Even though historically the sea level was variable due to changes in regional climate, the current change is due to modifications in water inflow from the two main tributaries, the Amu Darya and Syr Darya rivers. ...
The Aral Sea basin is one of the most anthropogenically modified areas of the world; it is also a zone of a water-related ecological crisis. We concentrate on studying water security of five countries in the region: Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. These countries share the same recent history of being a part of the Soviet Union, and inherit their water regulation from the planned economy of that time that was targeted at maximizing agricultural output through diverting the river flow into an extensive and largely ineffective network of irrigation canals. The current water crisis is largely due to human activity; however the region is also strongly impacted by the climate. Climate change will contribute to water problems, escalating irrigation demand during the drought period, and increasing water loss with evaporation. The future of the countries of the Aral Sea basin then depends on both the regional scenario of water management policy and a global scenario of climate change, and is integrated with global socioeconomic scenarios. We formulate a set of regional policy scenarios ("Business as Usual", "Falling Behind" and "Closing the Gap") and demonstrate how each of them corresponds to IPCC SRES scenarios, the latter used as an input to the General Circulation Models (GCMs). Then we discuss the relative effectiveness of the introduced scenarios for mitigating water problems in the region, taking into account the adaptation through changing water demand for agriculture. Finally, we introduce the results of multimodel analysis of GCM climate projections, especially in relation to the change in precipitation and frequency of droughts, and discuss the impact of climate change on future development of the region.
... messanensis and A . ehrenbergii were also considered as brackish-water-favoring species in previous studies (e.g., Rijstenbil, 1987;Sancetta, 1990;McQuoid and Hobson, 2001;Mirabdullayev et al., 2004). In the southern YS, the proportions of D . ...
The spatial distribution of siliceous microfossils (diatoms and silicoflagellates) in the surface sediments was mapped at 113 sites in the Yellow Sea and sea areas adjacent to the Changjiang (Yangtze) River, China. In total, 267 diatom taxa and two silicoflagellate species were identified from the sediments. The spatial variations in abundance and diversity were classified into three distinct geographic patterns using Q mode clustering: a south-north geographic pattern, a coastal-offshore pattern and a unique pattern in the Changjiang River mouth. The south-north geographic pattern was related to the spatial variations in sea temperature. Coscinodiscus oculatus, a warm-water species, indicated these variations by a gradual decrease in abundance from the south to the north. The coastal-offshore pattern was in response to the spatial variations in salinity. Cyclotella stylorum, Actinocyclus ehrenbergii and Dictyocha messanensis, the dominant brackish species in coastal waters, significantly decreased at the isobaths of approximately 30 m, where the salinity was higher than 31. Paralia sulcata and Podosira stelliger indicated the impact of the Yellow Sea Warm Current in the central Yellow Sea. The unique pattern in the Changjiang River mouth showed the highest species diversity but lower abundance, apparently because: freshwater input can significantly increase the proportion of brackish species; nutrients can supply the growth of phytoplankton; and high sedimentation rates can dilute the microfossil abundance in the sediments. Our results show that an integration of environmental factors (e.g., nutrient levels, sedimentation rate, sea temperature, salinity and water depth) determined the spatial characteristics of the siliceous microfossils in the surface sediments.
... The RMS error estimated for our observations shows that for the Aral Sea the errors should be larger then 4 cm. One of the reasons is that the presence of snow and ice during winter in the Big Aral (Kouraev et al., 2003, 2004 generates additional errors in the height measurements, since the reflection of the altimeter signal in the ice differs significantly from the reflection over open water. ...
... C. stylorum displayed a significantly negative correlation with salinity and water depth. C. stylorum is considered to favor brackishwater (e.g., McQuoid and Hobson, 2001;Mirabdullayev et al., 2004) and usually dominates in coastal waters with salinities of ≤31 (Jiang, 1987). The annual average salinity in the Bohai Sea is approximately 30-31, which is mainly controlled by the amount of river input and Yellow Sea intrusion. ...
... In a shallow coastal lagoon in Spain, C. salinarius was present in water whose salinity varies from 6 to 60 g l −1 (Drake & Arias 1995), in the Emporda Wetlands (NE Iberian Peninsula), Gascón et al. (2007) this species was described as a mesohaline to metahaline species (salinity varying from 7 to 43 g l −1 ). Chironomus salinarius was also reported in the western basin of the Aral sea (Mirabdullayev et al. 2004), and in a hypersaline environment (salinity over 65 g l −1 ) in the Mediterranean area, with a range of salinity varying from 14 to 45 g l −1 (Marchini et al. 2008;Ponti et al. 2007;Ali & Majori 1984;Ali et al. 1994;Ceretti et al. 1987;Fuentes et al. 2005;Suemoto et al. 2004). High productivity seems to be a characteristic of all saline waters, chironomid larvae in two saline rivers (including C. salinarius) had high monthly production in August, 16.7 g m -2 month -1 , dry weight, which was nearly comparable to annual production in some freshwater rivers (Zinchenko et al. 2014). ...
Cytology and ecology of Chironomus (Chironomus) salinarius Kieffer, 1915 (Diptera, Chironomidae) was examined from material collected in the saline rivers of the Lake Elton basin (Volgograd region, Russia). Larvae of salinarius-type were identified as C. salinarius on the basis of their karyotype. The species is redescribed on the basis of all metamorphic stages. The reared imago and karyotype were obtained from larvae of the same population. The karyotype of C. salinarius, detailed mapping of the 5 chromosome arms A, C, D, E, F and characteristics of chromosome polymorphism are provided. Information on distribution and ecology of C. salinarius from the saline rivers (total mineralization 6.8-31.6 g l-1) of the Lake Elton basin is also given. Chironomus salinarius is a common in the saline rivers and occurs in sediments with high silt content. On the basis of recent samplings C. salinarius appears to be very abundant in saline, mesotrophic as well as in eutrophic rivers. Chironomus salinarius accounted for 49-66% of total abundance of zoobenthos in water with salinity up to 13-31.6 g l-1.
... This species is mainly abundant when the sediment contains a very high diatom concentration that point to a relatively low dissolution rate of the frustules within the water column. Although A. octonarius is a marine diatom it was a dominant species in the Aral Sea in 1960(mirabdullayev et al. 2004). saPozhnikov et al. (2009 pointed to the dependence of diatom assemblage composition on water depth. ...
This study assesses changes in the environmental conditions in Chernyshov Bay (northern part of Aral Sea Western Basin) during the last ~2 ky from geochemical and diatom analyses of sediment core C2/2004. Comparison of fossil assemblages with the contemporary distribution of diatoms in the Aral Sea suggests that
considerable changes occurred in water level as well as salinity. Deposits with high diatom concentrations and
dominance of the marine species Actinocyclus octonarius Ehrenberg are interpreted as periods of high water
level, whereas replacement by Tryblionella compressa (Bailey) Boyer is considered to indicate lake level fall. On
the other hand sediments with low diatom concentration represent higher freshwater input and therefore salinity decrease. This interpretation is supported by estimates of siliciclastic and chemogenic sediment components. A chronology of major lake stages is derived and roughly agrees with recent findings from other studies.
... Moreover, Small et al. (2001) based their analysis on the data prior to the separation of the Big and Small Aral (when salinity was around 30 ppt) and did not take into account the very high and non-homogeneous recent increases of salinity of the Big Aral. Even if salinity measurements in the Big Aral Sea are sparse and not well assessed, it is known that by 2002 salinity reached over 80 ppt (Zavialov et al. 2003) in the western part and around 100 ppt to 120 ppt in the eastern part in 2001 (Mirabdullayev et al. 2004 ). Because the Big Aral is still drying , the salinity should still be increasing. ...
The Aral Sea was one of the biggest lakes in the world before it started to shrink in the 1960s due to water withdrawal for land irrigation. Sea level decreases led to the separation of the Aral Sea into two basins - the Small Aral in the north and the Big Aral in the south. For several decades there were no continuous observations of Aral Sea level, and the few data that exist are fragmentary or unavailable. We present observations of the Big Aral Sea level estimated from the TOPEX/Poseidon (T/P) altimetry with high temporal resolution over the last decade (1993-2004). Since sea volume is one of the key parameters for the studies of water balance, we use the T/P-derived time series of sea level and a dedicated digital bathymetry model (DBM) to reconstruct temporal changes in the Aral Sea surface and volume. We introduce variations of the sea volume as the new constraint for the water budget of the Big Aral Sea. This is an important step toward estimating detailed seasonal and interannual changes of the water budget. We assess various existing components of the water budget of the Aral Sea and discuss the quality of the existing data and their applicability for establishing detailed water balance. In particular, large uncertainties in estimating the evaporation and underground water supply are addressed. Desiccation of the Aral Sea resulted in dramatic changes in the salinity regime and, consequently, affected its aquatic ecosystems. We also discuss changes in the aquatic fauna and their possible evolution under continuing desiccation of the Big Aral Sea. Combining satellite altimetry with other parameters of the water budget offers a promising potential for assessing temporal changes in the water budget of arid or semi-arid regions, even those with a poor ground monitoring network.
... The observed warming signals in the Caspian and Aral Seas may come from several factors. For the Aral Sea, this may be partly explained by the continuing decrease of sea volume (and thus of heat storage capacity) and the increase of salinity, that from 1995 to 2001 increased in the central part of the Aral Sea from 42 to 155 –166 ppt (Mirabdullayev et al., 2003). This increase of salinity would have shifted the freezing temperature (without account of the particularities of salt composition of the Aral Sea) from À2.27 to À8.96 jC, using the formula T fr =À0.054 * S from Zubov (1945), where T fr is the freezing temperature and S is the salinity in ppt. ...
Time and space variations of ice cover in the Caspian and Aral Seas from historical and satellite data are discussed. Existing published continuous time series of ice cover parameters for these seas stop in 1984 – 1985; the results of observations for later periods are heterogeneous and mostly unpublished. The current lack of time series for ice cover parameters since the mid-1980s may be filled successfully by using microwave satellite observations that provide reliable, regular and weather-independent data on ice cover. In our study, we use the synergy of two types of satellite observations: (i) passive microwave data from SSMR and SSM/I sensors (since 1978) as well as (ii) a combination of simultaneous data from active (radar altimeter) and passive (radiometer) microwave instruments onboard the TOPEX/Poseidon satellite (since 1992). An assessment of ice conditions from historical observations is given to provide a background to compare with satellite-derived data. The ice algorithms were applied for satellite data; series of dates of first and last observation of ice cover, duration of ice season as well as ice extent area have been computed for various regions of the Caspian and Aral Seas. These time series show pronounced regional, seasonal and interannual variability. There is a marked decrease of both duration of ice season and ice extent since the winter 1993/1994. Several factors that may explain this warming signal are discussed, as well as existing and potential implications of changes in ice conditions for industrial activity and the sea ecosystems. D 2004 Elsevier B.V. All rights reserved.
... Human communities suffer many negative consequences as a result of this, and a lost of valuable biological resources among them. The changes of hypersaline lakes are characterized by wide fluctuations in salinity, leading to a significant restructuring of their biodiversity and ecosystem functioning (Aladin and Potts, 1992;Mirabdullayev et al., 2004;Velasco et al., 2006;Balushkina et al., 2009;Carrasco and Perissinotto, 2012). ...
All over the world hypersaline lake/lagoons are threatened by climate change. The marine Bakalskoye Lake (Ukraine) was studied in 2000-2012. The paper considers changing crustaceans within the context of the lagoon changes. A sharp drop of salinity occurred in 2004 due to a changed wind rose because the strong winds of Western direction began to dominate, and as a result, washing away of the spit began to be more intensive; and marine water inflow into the lake increased. The structure of primary productivity has changed completely; the total primary production decreased. A list of crustacean species found in the lake includes 19 species. In 2004 there was a change of the composition of crustaceans due to three factors - a change of salinity, an increase of erosion, and massive transport of marine organisms into the lake. Integral characteristics of zooplankton also significantly changed. Impact of climate change on crustaceans is not only direct, but through an extensive network of intermediate effects which are discussed. The study results are of more than local relevance; it has a general ecological importance because can help to better understand that the realizations of general climate change impacts on local level are diverse.
В осетроводстве актуально применение нетравматичных методов определения пола осетровых рыб и стадий зрелости гонад. Одним из таких методов является ультразвуковая диагностика (УЗ-диагностика). Этот метод был применен при проведении бонитировочных работ с осетровыми видами рыб в установке замкнутого водоснабжения (УЗВ) ТОО «Учебно-научный комплекс опытно-промышленного производства аквакультуры» (ТОО «УНКОППА») Западно-Казахстанской области. В результате проведения УЗ-диагностики были получены данные о половой структуре и развитии гонад сибирского осетра (Acipenser baerii) возраста 6+, 7+ и 12+, а так же промышленных гибридов осетровых рыб – бестера и РОЛО возраста 12+. По результатам УЗ-диагностики установлено, что на III переходной стадии зрелости находились 15% особей сибирского осетра возраста 6+. В результате оценки группы возраста 7+ с помощью УЗ-сканирования были определены самки, перспективные для использования в маточном поголовье. Для осетровых возраста 12+ из маточного поголовья, находящихся на завершающей стадии созревания икры, были определены стадии зрелости ооцитов. В конце была определена группа рыб, направленных на искусственную зимовку с целью получения икры.
Currently, the Aidar-Arnasai Lake System (AALS) is of great environmental and commercial importance for Uzbekistan. The article discusses the influence of mineralisation, temperature and diversity of biotopes on the change in the species composition in the lakes. The largest number of species is recorded in oligohaline water in the lakes’ littoral zones. They are dominated by the Rotifera and Cladocera and show a greater number of species in the spring. Areas with mesohaline water are dominated by Copepoda, showing the largest number of species in the winter in both littoral and pelagic zones. Biomass of zooplankton poorly correlates with salinity. Depth impacts reliably the distribution of zooplankton biomass, while the spatial accumulation of zooplankton biomass depends on temperature.
The buoyancy of Artemia resting eggs is a feature with both biological and economic importance. Since the buoyancy of resting eggs is dependent on the specific weight of the eggs or salinity of ambient water, we suppose that habitat salinity may exert a selection pressure on resting egg buoyancy, and thereby lower habitat salinity may result in better floating capacity of resting eggs and vice versa. In this study, we compared the floating capacity of resting eggs from 25 Artemia populations. The results showed that the floating capacity of resting eggs varied greatly among different populations. The minimum salinity to float some eggs varied from 0 to 180. The salinity at which all resting eggs floated varied from 80 to 320. The FS50 (salinity with 50% eggs floating) of Zhundong and Yuncheng population was not detectable (over 50% eggs floating in distilled water), that of Kyêbxang Co population was 4.3, while the maximum value found in Dabancheng population was 234.5. In terms of the ‘apparent specific weight’ of resting eggs, 18 populations exhibited a single-peak distribution pattern, while the other 7 populations showed a multiple-peak or non-peak distribution. Negative correlations were found between FS50 and chorion thickness, and between FS50 and the volume percentage of the chorion in eggs, supporting a previous standpoint that shell thickness was a determinative factor for the floating capacity of resting eggs. A positive correlation was determined between FS50 and habitat salinity. The hypothesis that habitat salinity may cause a directional selection on the buoyancy of resting eggs seems to be true.
In the first half of the 20th century, the Aral Sea was a single terminal water body of two rivers in the arid zone. The main part of its water area was brackish with specific aboriginal brackish water ecosystems. Since 1960s, decrease of level and salinization of the Aral Sea have begun. Due to the structure of its depression the Aral Sea began to split into several residual water bodies. In 1988–1989, when level decreased by 13 m, the Aral Sea was divided into 2 polyhaline terminal lakes with marine ecosystems – the Large and Small Aral. In the fauna, only widely euryhaline species remained due to water salinization and introduction of exotic species. Piscifauna consisted of introduced species of marine origin. In spring 1990, level of the Small Aral increased and a water flow to the Large Aral appeared. The threat appeared of moving the Syrdarya River mouth to the Large Aral. In August 1992, a dike was built in the Berg’s Strait. Salinity growth in the Small Aral stopped; the salinity began to decrease what was favorable to the fauna. Conditions of transitioinal brackishwater-marine salinity zone were formed. In April 1999, the dike was destroyed by a storm. Construction of new solid dike started in 2004 and was finished in autumn 2005. After Aral Sea division, salinization and level fall in the Large Aral became faster. The Large Aral was divided into the Western Aral, Eastern Aral and Tschebas Bay. Salinity in the eastern basin is growing faster than in the western one. In the late 1990s, the Large Aral became hyperhaline with specific fauna. Some invertebrate species inhabiting saline water bodies in the Aral Sea region moved into the Large Aral by natural way. Among them, the brine shrimp (Artemia parthenogenetica) became predominating in zooplankton.
Бухоро тумани тупроқлари суғориладиган ўтлоқи тупроқларга мансуб
бўлиб, суғорма деҳқончиликда муҳим ўрин тутади ва улар ўзига хос
морфогенетик тузилишига, физикавий ва кимёвий хусусиятларига эга бўлиши,
улардан оқилона фойдаланиш учун алоҳида агромелиоратив ва агротехник
чора тадбирларни қўллашни талаб қилади.
Due to catastrophic desiccation, today’s Aral Sea consists of a few separate residual basins, characterized by different ecological conditions (the Large Aral, Lake Tshchebas, the Small Aral). This study is the first report on dissolved methane concentrations in these basins. Overall, 48 water samples were obtained and analyzed for methane content. High values of dissolved methane in the anaerobic layer of the Large Aral Sea, including the Chernyshev Bay, are apparently caused by damping of vertical mixing and decomposition of abundant organic matter in anoxic conditions. The estimated methane flux from the surface of the Large Aral Sea is actually higher than that from many other lakes in the world. For the anoxic layer of the Large Aral, certain relations between distributions of methane and other hydrochemical parameters, including dissolved oxygen and hydrogen sulfide, were found. In the brackish Small Aral Sea, methane content was moderate. Lake Tshchebas exhibits intermediate conditions between the Large and the Small Aral seas in terms of salinity and methane concentration. The observed differences of methane content and distributions in separate residual basins are linked with the differences of their mixing and oxygenation regimes.
In order to depict the distribution of diatom fossils in surface sediments and to establish a reliable reference data for further paleoenvironmental study in the Changjiang (Yangtze) River estuary and its adjacent waters, the diatom fossils from 34 surface sediment samples and their relationship with environmental variables were analyzed by principal component analysis and redundancy correspondence analysis. The diversity and abundance of diatom fossils were analyzed. Some annual average parameters of the overlying water (salinity, temperature, turbidity, dissolved oxygen, depth, dissolved inorganic nitrogen, dissolved inorganic phosphate and dissolved inorganic silicate) were measured at each sampling site. A total of 113 diatom taxa and one silicoflagellate species were identified in the investigation area. Diatom fossils were better preserved in fine sediments. The absolute abundance of diatom fossils did not significantly differ between inshore and offshore areas, the species diversity decreased from inshore to offshore. This may be because high nutrients and low salinity promoted the growth of more brackish species in coastal waters. The diatom taxa were divided into three groups, on the basis of their response and indication to environmental changes. For example, Actinocyclus ehrenbergii and Cyclotella stylorum were dominant in coastal waters (Group 1 and Group 3) with high nutrients and low salinity; the relative abundances of Paralia sulcata and Podosira stelliger were significantly higher in offshore sites (Group 2, average 39.5%), which were characterized by high salinity and deep water. Four environmental variables (salinity, dissolved inorganic nitrogen, temperature and water depth) explained the composition and distribution of diatom taxa independently ( P< 0.05), this finding can be applied in further paleoenvironmental reconstruction research in this area.
We present the first comprehensive taxonomic and environmental study of dinoflagellate cysts in 185 surface sediment samples from the Black Sea Corridor (BSC) which is a series of marine basins extending from the Aegean to the Aral Seas (including Marmara, Black, Azov and Caspian Seas). For decades, these low-salinity, semi-enclosed or endorheic basins have experienced large-scale changes because of intensive agriculture and industrialisation, with consequent eutrophication and increased algal blooms. The BSC atlas data provide a baseline for improved understanding of linkages between surface water conditions and dinoflagellate cyst (dinocyst) distribution, diversity and morphological variations. By cross-reference to dinocyst occurrences in sediment cores with radiocarbon ages covering the past c. 11,700 years, the history of recent biodiversity changes can be evaluated. The seabed cyst samples integrate seasonal and multi-year data which are not usually captured by plankton samples, and the cyst composition can point to presence of previously unrecorded motile dinoflagellate species in the BSC. Results show the presence of at least 71 dinocyst taxa of which 36% can be related to motile stages recorded in the plankton. Comparison with sediment core records shows that five new taxa appear to have entered or re-entered the region over the past century. Statistical analysis of the atlas data reveals the presence of four ecological assemblages which are primarily correlated with seasonal and annual surface water salinity and temperature; correlation with phosphate, nitrate and silicate nutrients, chlorophyll-a and bottom water oxygen is less clear but may be important for some taxa. Biodiversity indices reveal strong west − east biogeographical differences among the basins that reflect the different histories of Mediterranean versus Ponto-Caspian connections. The atlas data provide a standardised taxonomy and regional database for interpreting downcore cyst variations in terms of quantitative oceanographic changes. The atlas also provides a baseline for monitoring further changes in the BSC dinocysts that may accompany the accelerating development of the region.
Chironomidae larvae may represent more than 70% of total Arthropoda numbers in hypersaline waters. Crimea, the largest peninsula of the Black Sea, has more than 50 hypersaline water bodies of marine and continental origin. Chironomidae larvae are common components of their ecosystems, but they still are poorly understood. This paper summarizes the results of a long-term study (2007–2016) of chironomids in Crimean hypersaline waters. More than 400 samples from 38 water bodies were used for analysis. The maximum salinity of water bodies containing Сhironomidae larvae was between 320 and 340 g/L. At first it was shown that Baeotendipes noctivagus (Kieffer, 1911) is the most halotolerant chironomid species in the
world. Frequency of larvae occurrence varied and was negatively dependent on salinity. Four chironomid species were found: B. noctivagus, Cricotopus gr. cylindraceus (Kieffer, 1908), Tanytarsus gr. mendax Kieffer, 1925 and Paratanytarsus sp. Ceratopogonidae larvae were also found twice, at salinities of 150 and 270 g/L. B. noctivagus was the most common species, which occurred in 81% of samples with chironomids. Abundance of larvae fluctuated widely and reached high numbers: in plankton – to 8 thousand/m3, in floating green algae mats – up to 3 thousand/m2, and in benthos – up to 9 thousand/m2. Nonlinear dependence of chironomid abundance from salinity was observed; maximum abundance was at salinity levels of between 150 and 170 g/L. The average weight of larvae of 0.05–1.50 mm in length varied little in the samples; however, larvae of greater length had a significantly different average weight. Larvae of 8 mm in the samples had the average actual weight, which ranged from 0.750 to 2.203 mg.
The Aral Sea in 2012 consisted of four residual water bodies with different hydrological regimes. The Kok-Aral dam raised and stabilized the level of the Small Aral Sea. Growth of salinity has stopped and a process of gradual salinity reduction is in progress. By the autumn 2011 water salinity in the open part of the Small Sea dropped to 8 g/l. The future of its biota depends on future salinity. If the current regime will remain, then the decrease in salinity will continue and the Small Aral will turn from a brackish to a nearly freshwater body. This freshening will cause substantial changes in the fauna as a result of the disappearance of marine and brackish species and reintroduction of freshwater forms. Currently two variants of further rehabilitation of the Small Aral are under consideration. The first one involves an additional dam at the entrance to Saryshaganak Gulf to create a reservoir out of it and the filling of this water body via a canal from the Syr Darya. The Small Sea under this plan would then have both freshwater and brackish water parts. The second variant is to increase the level and area of the Small Aral Sea by raising the height of the Kok-Aral dam. In this case, all the Small Sea remains brackish except the existing freshened zone in front of the Syr Darya Delta. Both these variants would avoid further strong freshening of the Small Aral Sea and associated with this adverse changes in the fauna. The expected future of the biota of the residual hyperhaline water bodies of the Large Aral is quite different. In this case, there is no possibility of reducing their salinity leading to recovery of fauna represented by marine and widely euryhaline species. On the contrary, even stronger salinization is likely. The East Large Aral Sea could dry out completely, and the West Big Aral could turn into a lifeless water body akin to the Dead Sea.
Regression of the Aral Sea began in 1961. At first changes in the fauna were primarily the result of fish and invertebrates introductions. In the 1970s regression accelerated. The main factor influencing fauna is increasing water salinity. In 1970s–1980s invertebrate fauna went through two crises. Freshwater species and brackish water species of freshwater origin became extinct first. Then Ponto-Caspian species disappeared. Marine species and euryhaline species of marine origin survived, as well as species of inland saline waters fauna. By the end of the 1990s the Large Aral became a complex of hyperhaline lakes. Its fauna was passing through the third crisis period. Incapable of active osmoregulation, hydrobionts of marine origin, and the majority of osmoregulators disappeared. A number of species of hyperhaline fauna were naturally introduced into the Large Aral. Salinization of the Aral Sea has resulted in depletion of parasitic fauna. All freshwater and brackish-water ectoparasites and significant part of helminthes began to disappear. Together with the disappearance of hosts, the parasites associated with them in their life cycle had to disappear. Regulation of the Syr Darya and Amu Darya and decreasing of their flow altered living conditions of the Aral Sea fishes, especially their reproduction. In 1971 there were the first signs of negative effects of salinity on adult fishes. By the middle of the 1970s natural reproduction of fishes was completely destroyed. Commercial fish catches decreased. By 1981 the fishery was lost. In 1979–1987 flounder-gloss was introduced and in 1991–2000 it was the only commercial fish. After the flow of the Syr Darya again reached the Small Aral, aboriginal fishes began migrating back to the sea from lacustrine systems and the river. This allowed the achievement of commercial numbers of food fishes. Since the end of the 1990s the Large Aral Sea is a lake without fishes. Regression and salinization of the Aral Sea caused destruction and disappearance of the majority of vegetational biocenoses.
Diatom assemblages in a rice paddy inundated by the 2011 Tohoku Earthquake tsunami were studied. We collected diatom samples from a rice paddy in Sabusawa Island in Miyagi Prefecture on 14 August 2011. The rice paddy was intruded by seawater during the high tide of the spring tide as a result of destruction of the coastal levee and the land subsidence after the earthquake. The salinity of the paddy was slightly higher than that of the coastal seawater, and naturally, rice was not cultivated at that time. In total 117 diatom taxa （including 22 unidentified ones） belonging to 50 genera were observed. The diatom assemblages consisted of fresh, brackish, and marine water species, and moreover, extinct Miocene marine diatoms. The dominant species was Tabularia parva on Zannichellia palustris and in a floating algal floc, and Navicula phylleptsoma on the surface soil. Halamphora luciae was subdominant in all samples. Judging from the past literature, these diatoms all tolerate changes in salinity.
The present paper deals with the results of the first study (April and August, 2006–2007) of the taxonomic composition of macrozoobenthos in the highly mineralized Khara River. The study revealed 35 species and taxa of the rank above species. Data were obtained on the spatial distribution of the species composition dynamics and on the quantitative development of the macrozoobenthic community. The dependence of the structure of bottom communities on the parameters of the river’s trophic status, biotopic diversity, and changes in hydrochemical parameters was determined. The environmental factors (total mineralization, ionic composition, pH, oxygen content, water temperature, overgrowth by macrophytes) influencing structural changes in macrozoobenthic community were determined. It is shown that diversity, number, and biomass of halotolerant macrozoobenthic communities increase with a rise in water mineralization from 6.9 to 14 mg/L. A new halophilic chironomid species of the family Chironominae, Tanytarsus kharaensis Zorina et Zinchenko, has been found.
The species composition, cell concentration, and biomass in the surface layer were determined at 10 stations in the central part of the Western Basin (WB) and one station in the Eastern Basin (EB) of the Large Aral Sea. A total of 42 algae species were found. Diatoms had the highest number of species. The similarity of the phytoplankton composition in the WB was high, whereas the phytoplankton composition in the WB and EB differed significantly. In the WB, the cell concentration and biomass of the phytoplankton varied from 826 × 103 to 6312 × 103 cells/l (the mean value was 1877 × 1586 × 103 cells/l) and from 53 to 241 μgC/l (the mean value was 95 × 56 μgC/l). In the EB, the phytoplankton abundance was 915 × 103 cells/l and 93 μgC/l. The vertical distribution of the phytoplankton in upper 35 m was investigated at one station in the WB. The maximum values of the algal cell concentration and biomass were recorded under the thermocline at the 20 m depth. The integrated biomass of the phytoplankton was 14 gC/m2.
The Aral Sea is a terminal lake amidst the deserts of Central Asia. Its size and water balance are fundamentally determined
by river inflow and evaporation from its surface. Until the 1960s, the Aral was the world’s fourth largest lake in surface
area. Over the past four decades, this water body has rapidly and steadily shrunk as countries in the Aral Sea Basin have
increasingly taken inflow from its two influents, the Syr Dar’ya and Amu Dar’ya, for expansion of irrigation. The Aral’s diminution
has directly and indirectly led to an array of severe problems in the surrounding region, ranging from degradation of major
terrestrial and aquatic ecosystems to deterioration of human health and welfare. National, regional, and international efforts
are underway to cope with these, but even their partial alleviation will be enormously costly and require many years. Full
restoration of the Aral Sea to its former state is, at best, a remote possibility for the more distant future. However, rehabilitation
of portions of it and adjacent areas that would partially restore former ecological functions and economic uses are feasible.
References
The construction of a dam between the Small and Large Aral Sea in 1993 has had an effect on biological communities. From field and laboratory investigations and analysis of the literature, the structure and function of the main plant and animal communities in the northern (Small) Aral Sea are described and discussed, first, for the period before 1985, and, second, between 1985 and 1994. A prognosis for future changes is provided.
The macrozoobenthos was investigated at eight sites in the Aral Sea inshore zone and in the lower reaches of the Syrdaria river. In the sea, the benthos comprised bivalve molluscsSyndosmya segmentum Recluz andCerastoderma isthmicum Issel, gastropods fromCaspiohydrobia Starob., the polychaeteNereis diversicolor O.F. Mller and the crabRhithropanopeus harrisii tridentatus (Maitland). In the Syrdaria, MysidaeParamysis lacustris (Czern.) and GammaridaeDikerogammarus aralensis (Uljanin) were found. These taxa have not been recorded from the Sea since the 1970s. The total zoobenthos biomass and density varied between the investigated Sea areas from 92 to 582 g/m2 and from 1,600 to 39,000 ind./m2, respectively. Spatial and temporal salinity changes within the range 20–41 g/L did not affect macrozoobenthos composition and structure. The conclusion is that the benthic ecosystem of the Aral Sea was in a state of comparative stability from the middle of the 1980s to the middle of the 1990s. Analysis of the zoobenthos in the inshore zone is proposed as a convenient and accessible method for monitoring the status of the zoobenthos of the entire Aral Sea.
The benthos of the Small and Large Aral Sea was investigated in 1989. OnlyNereis diversicolor, Syndosmya segmentum, Cerastoderma isthmicum, Caspiohydrobia spp., Chironomidae andPalaemon elegans occurred in the Small Sea. In the Large Sea, the benthos was similar, but Chironomidae were absent andRhithropanopeus harrisii was present.
Makrozoobenthos Aralskogo morya v nachalnyi period ego osoloneniya
- Andreeva
Changes in the structure and function of biological communities in the Aral Sea, with particular reference to the northern part (Small Aral Sea), 1985–1994: a review
- Aladin
Sovremennoe gidrofizicheskoe i gidrobiologicheskoe sostoyanie zapadnoy chasti Aralskogo morya
- Zavialov
Estestvennoe sostoyanie ecosystemy Aralskogo morya i eye izmenenie pri antropogennom vozdeystvii
- Aladin
Kardinalnye izmeneniya v sostave bioty Aralskogo morya
- Joldasova
Novye dannye o vodoroslyakh Aralskogo Morya
- Kiselev
Sovremennoye sostoyanie ekosistemy Zapadnoy chasti Aralskogo morya
- Mirabdullayev
Ozero Sudochie kak refugiums aralskoy gidrofauny
- Mirabdullayev