Saline Water Bodies Research Articles

Spatial Patterns of Organic and Inorganic Carbon in Lake Qinghai Surficial Sediments and Carbon Burial Estimation

Lake carbon burial is of vital significance in global carbon cycle and carbon budget, particularly in the large deepwater lakes. However, carbon burial in large deepwater lakes is hard to estimate due to the difficulty in obtaining high spatial-resolution samples. In this study, we investigated distributions of total organic carbon (TOC) and inorganic carbon (TIC), two main carbon components in lake sediments, based on dozens of surficial sedimentary samples (n= 26) covering whole Lake Qinghai, the largest saline lake in China. The results showed that the TOC content, with a range of 1.4–4.8%, was significantly higher in the lake area near the northern lakeshore where human activities are concentrated and lower in the lake areas near the Buha River mouth and the eastern lake area. In contrast, the TIC content, ranging from 1.5 to 3.8%, increased from the northwestern and southeastern lake areas toward the lake center, and mainly depended on hydro-chemical and hydraulic characteristics. The inorganic carbon burial (47.77 ± 19.73 Gg C yr−1) was approximately equal to organic carbon burial (47.50 ± 22.68 Gg C yr−1) and accounted for about 50% of the total carbon burial (95.27 ± 37.74 Gg C yr−1), suggesting that saline lakes constitute a large inorganic carbon pool in addition to an organic carbon pool. Because of saline water body type in arid and semiarid regions and alpine Qinghai–Tibet Plateau, lakes in these regions have huge inorganic carbon burial potential and important contributions to the global carbon budget.

The White-headed yellow wagtail <em>Motacilla flava leucocephala</em> (Przewalski, 1887): migration, movements, and breeding and wintering ranges

The subspecies leucocephala of the western yellow wagtail Motacilla flava is endemic to the Altai-Sayan Ecoregion (Central Asia). The occurrence of leucocephala is associated with saline water bodies and solonchak habitats. Its distribution, especially outside the breeding season, is still uncertain. The aim of this work is to better define the breeding range, migratory movements, and the wintering range of this subspecies and provide guidance to distinguish whiteheaded intraspecific hybrids from the true leucocephala subspecies. The reproductive range of leucocephala is concentrated near lakes and wetlands in the Great Lakes Depression (north-west Mongolia) and in the flat southern part of the Tuva Republic (Russian Federation). The small population uses two separate areas for wintering: the eastern equatorial Africa reached through the Great Rift Valley Flyway and the Indian subcontinent reached along a route that bypasses the great belt of mountains and plateaus of central Asia to the west.

Geochemical characteristics and organic matter accumulation of argillaceous dolomite in a saline lacustrine basin: A case study from the paleogene xingouzui formation, Jianghan Basin, China

Shale oil resources have been discovered in argillaceous dolomite in the Lower Member of Paleogene Xingouzui Formation (LXF) of the Jianghan Basin, opening up a new field of shale oil exploration and development. Previous studies have mainly focused on the evaluation of reservoir quality, but the research on the enrichment mechanisms of organic matter (OM) in argillaceous dolomite is very limited or unknown. On the basis of organic geochemical and mineralogical data, combined with sedimentological analyses, the factors controlling the differential enrichment of OM in the LXF Member II oil Bed argillaceous dolomite are studied. The results show that the average TOC content of the samples is greater than 1.0%, which could be regarded as good source rocks. The kerogen type is mainly type II, with a small amount of type I and type III, and most of the samples are in the low-mature stage. Vertically, the development of the LXF Member II oil Bed argillaceous dolomite can be divided into three stages: the lower section (LS) has TOC content ranging from 0.57 to 4.95%, the middle section (MS) has a higher TOC content, between 0.55 and 9.52%, and the TOC content of the upper section (US) is relatively low, between 0.41 and 3.49%. The distribution of biomarkers showed that both higher plants and aquatic organisms contributed to the OM accumulation. The parameters of biomarkers such as pristane/phytane (Pr/Ph), gammacerane/C30 hopane (G/H), extended tricyclic terpane ratio (ETR) and their degree of dispersion, as well as sedimentological characteristics, indicate that the LS was deposited in a stratified deep waterbody with anoxic bottom water, the MS was deposited in a saline stratified moderate-deep waterbody with anoxic bottom water, and the US was deposited in a disturbed saline waterbody. Different sedimentary environments controlled the source of OM, the effectiveness of nutrients recycling and preservation conditions, which jointly affect the enrichment of OM. The stratified moderate-deep waterbody with anoxic bottom water and no physical disturbances, coupled with low terrigenous organic matter (TOM) inputs and the contribution of algae and other phytoplankton, are the best conditions for the enrichment of OM in argillaceous dolomite.

When a mid-ocean ridge encroaches a continent: Seafloor-type hydrothermal activity in Lake Asal (Afar Rift)

At the place where the submarine Aden Ridge encroaches on the African continent and interacts with the East African Rift system, two small basins form: Ghoubbet-al-Kharab and Lake Asal. Whereas Ghoubbet-al-Kharab is connected to the open ocean, Lake Asal is a typical example of oceanic “embryo”, which is defined as a system that is detached from the ocean, but has features of a marine basin with an oceanic type crust and a seawater-based water body. In order to shed light on the source of water, type of hydrothermal activity and hydrothermal deposits, and controls on the water chemistry in an oceanic “embryo”, we undertook a mineralogical-geochemical study of the lake water, hydrothermal fluids and hydrothermal carbonate deposits of Lake Asal. The geochemical analyses of lake water and hydrothermal fluids show that Lake Asal (located in an arid zone with strong evaporation and with no riverine input) is fed by seafloor-type hydrothermal fluids according to the following scenario: percolation of seawater along faults and cracks of extension in the rift, reaction of seawater with the hot basaltic rocks and hydrothermal fluid generation, discharge of the hydrothermal fluid in the Asal depression and accumulation of the Lake Asal water body. The fluid venting at the Lake Asal bottom is a mixture of 97% end-member hydrothermal fluid and 3% lake water. The calculated end-member hydrothermal fluid of this oceanic “embryo” is poorer in metals than the seafloor hydrothermal fluids of an open and evolved ocean. In addition to the seawater/rock interaction, the chemistry of Lake Asal is also controlled by evaporation leading to hyper salinity. In a hyper saline water body a number of hydrothermally supplied metals are stabilized as chloride complexes and accumulate. This results in a metal rich and mildly acidic “embryonic” ocean. Unlike an open and evolved modern ocean, the “embryonic” ocean located in an arid zone has heavy C and O isotope composition and light Zn and Fe isotope composition. Calcium isotope compositions of both types of ocean are similarly heavy. There are two genetically different sources of elements to the Lake Asal that are vertically separated: hydrothermal (lower, or bottom) and aeolian (upper, or surficial). Another important control on the lake water chemistry is the formation of carbonate spires at the lake bottom. Ca‑carbonate precipitation immobilizes substantial amount of hydrothermally supplied Ca and drives up the (Mg/Ca)mol of the lake water. Increasing (Mg/Ca)mol of the evolving lake water leads to changes in the mineralogy of spires: from low-Mg calcite to aragonite. Thus, the spire formation exerts a self-control on its mineralogy. Carbonate spire deposition affects also the Ca, Zn and Fe isotope composition of the lake water through adsorption or/and co-precipitation induced isotope fractionation.

A baseline quantitative assessment of deep-sea benthic fauna of the Gulf of Aqaba (Northern Saudi Arabia, Red Sea)

The Gulf of Aqaba (hereafter ‘the Gulf’) is a narrow, semi-enclosed, warm, high saline, and oligotrophic water body. This baseline study provides the first quantitative data on deep-sea (207–1281 m depth) benthos of the Gulf. Fifty-five benthic species (predominantly polychaetes) with a density of 160–670 ind. m−2, species richness of 11–25, and Shannon-Wiener diversity (H′) of 3.14–4.17 bits. ind.−1 were recorded from nine stations. The density and H′ of benthos of the Gulf are comparable with those of the Red Sea, while both are lower than those reported from the Arabian Sea and the Mediterranean Sea. The good-high ecological status of benthic communities indicates the absence of major stress in the deep-sea habitats of the Gulf. As large-scale urbanization is proposed in the Saudi coastal areas of the Gulf, this study is expected to provide a baseline dataset for future environmental impact assessments.

Assessment of surface energy balance algorithm for land and operational simplified surface energy balance algorithm over freshwater and saline water bodies in Urmia Lake Basin

To manage inland water resources, surveying the performance of remote sensing models for estimating the actual evaporation in arid regions is so important. Hence, this study aimed to assess the performance of two energy balance algorithms including surface energy balance algorithm for land (SEBAL) and operational simplified surface energy balance (SSEBop) in freshwater and saline water bodies. Another purpose of the present study was efficiency improvement in hypersaline lakes. In this regard, a practical salinity correction coefficient was used to overcome shortcomings of the selected models over saline Lake. The analysis of yearly lake water budget was used to assess the selected energy balance algorithms’ performance with a novel approach. These algorithms were investigated at Shahid Kazemi Dam Reservoir (as a freshwater body) and Urmia Lake (as a hypersaline water body) in Iran. The results showed that two selected algorithms estimated the evaporation rate at the selected freshwater body with a proper accuracy. The results showed the root mean square error for SEBAL result (RMSESEBAL) as 2.0 mm/day, correlation coefficient for SEBAL result (RSEBAL) as 0.80 mm/day, and RMSESSEBop and RSSEBop as 1.7 and 0.80 mm/day, respectively. However, these models overestimated evaporation over the hypersaline water body (RMSESEBAL = 88.4 mm/month, RSEBAL = 0.90 and RMSESSEBop = 39.9 mm/month, RSSEBop = 0.94). Salinity correction coefficient improved the results as RMSESEBAL = 19.8 mm/month, RSEBAL = 0.90 and RMSESSEBop = 13.4 mm/month, and RSSEBop = 0.94. In general, the algorithm performance was improved using the salinity correction coefficient in the chosen hypersaline water body.

Occurrence, distribution and removal of organic micro-pollutants in a low saline water body

A low saline backwater canal, mainly utilized for domestic and agricultural purposes, has been analyzed for the possible presence of organic micropollutants (OMP) and their potential removal was explored by multilayered microfiltration membranes. The qualitative as well as quantitative analysis were carried out for a span of one year using the technique of liquid chromatography connected with high resolution mass spectrometry (LC-Q-TOF-MS). The identification of the formally unknown compounds was initially done using non-target analysis based on the mass accuracy, isotopic pattern and MS/MS spectral interpretation. Results of the non target screening revealed the presence of 11 OMPs. Five of these OMPs were confirmed using standards; these include chlorophene (CHP), oxybenzone (OXY), N, N-diethyl-meta-toluamide (DEET), N, N-diethyl-benzamide (DEB) and dibutyl phthalate (DBP). Among the confirmed OMPs, the highest concentration was observed for DBP (244.61 ng l−1). The most frequently observed OMP in the study area was DBP while the least was DEB which is an insect repellent as well as a degradation product of DEET. The ecological risk associated with the target compounds has also been analyzed by calculating the risk quotient (RQ) and the results revealed that at the detected levels, these compounds are capable of causing low to medium risk. Low pressure (<0.3 bar) filtrations of the compounds were attempted using microfiltration (MF) and, poly(ethyleneimine)/poly(styrene sulfonate) (PEI/PSS) multi-layered MF membrane for spiked ultrapure water and also for natural water from the back-water canal. The batch mode illustrates nearly complete removal of CHP and OXY in spiked solutions and a good removal efficiency from natural water. The effect of coexisting ions and surfactants in feed is also illustrated. The high efficiency of the removal of both CHP and OXY, in such a complex medium highlights the potential application of the present method for the removal of similar OMPs in natural waters.

HYDROCHEMICAL EVALUATION OF THE AZRAQ UNCONFINED AQUIFER, JORDAN

The groundwater hydrochemical characteristics of the Azraq Basin were investigated and evaluated statistically. The presence of an underground saline water body in the Qa’ Al-Azraq area has made this specific part of the basin. &nbsp;38 samples from 38 GW wells were collected to understand the GW hydrochemistry of the Azraq unconfined aquifer that is mainly composed of marl, evaporites, limestone and clay formations. The PCA analysis indicates that Na, Mg, Cl, Ca, and K contribute the variance in the chemical composition of the GW samples. Piper, Durov and Wilcox diagrams indicated that the water types are mainly earth alkaline with prevailing SO4 and Cl, and alkaline water with prevailing SO4 and Cl. The main processes in the basin are dissolution or mixing and reverse ion exchange in which Na and Cl are prevailing. The GW is mainly oversaturated concerning aragonite, calcite and dolomite as indicated by the excess input of Mg and Ca ions from the rock-water interactions, while anhydrite (CaSO4), halite (NaCl), and gypsum (CaSO4.2H2O) are generally undersaturated. The effect of the agricultural activities in the study area is reflected by the positive correlation between NO3 and PC2. Wilcox diagram indicates that the samples are in the medium to very high salinity slots with the majority in the high salinity slot and in the low and medium alkali hazard zone, while few samples show high to very high alkali hazards. The simulated salinity for the next 30 years shows alarming danger and requires immediate attention as the Qa’ area is expected to become saline with TDS values of 2500 to 4600 mg/l, unsuitable to use for domestic and/or agricultural purposes. &nbsp;

Remote sensing, GIS, and Fieldwork Studies to assess and valorize groundwater resources in the springs area of oum-Er-rabiaa (moroccan Middle Atlas)

The basin of Oum-Er-Rabiaa is part of the Middle Atlas, it constitutes an important water resource on the scale of Morocco. The hydrogeological system of the region is characterized by many springs, some of which have a high salinity rate spilling into Oum-Er-Rabiaa river. The present study aims to investigate: Firstly, the distribution of lineaments along the major shear corridors crossing the area as well as their hydrogeological importance, and secondly, to verify the influence of geological characteristics on the physicochemical properties of the studied water bodies. This study is based on a combined analysis through: Remote Sensing, Satellite Imagery, Geographic Information Systems (GIS), Field Studies and Geochemical Analysis. The results demonstrated that the lithological and structural characteristics of the geological formations, play a predominant role in the creation of this hydrogeological system, as well as, in the diversity of the physicochemical proprieties of water resources in the area, these geological formations are mainly composed by: Liassic limestone characterized by a circulation of fresh water (fresh springs), this Liassic limestone is put in contact with the Triassic saline clays through geological faults, which is in the origin of the creation of saline springs contaminating the upstream of the Oum-Er-Rabiaa river. In the light of the decisive results obtained a set of solutions have been proposed such as the diversion of saline springs, the purification in situ, and the development of a fish farming project. These solutions aim to guarantee a better quality of water resources of the area, to preserve agriculture and to valorize the saline water bodies with a sustainable development perspective.

Relationships between aquatic invertebrate assemblages and environmental quality on saline wetlands of an arid environment

Wetlands are ecosystems with great ecological value due to their extraordinary biodiversity and the ecosystem services they provide. Saline wetlands have specific biological attributes and conservation significance because of the particular fauna they hold. In this study, we analyzed invertebrate assemblages, the conservation state, and environmental quality of the Desaguadero-Salinas del Bebedero Wetlands, in a RAMSAR site of central Argentina. Samples of water for physical-chemical analysis and aquatic invertebrates were taken at seven sites. A Simplified Index of Water Quality (SIWQ) and the Index of Conservation State of Lentic Somers Ecosystems (CSLSE) were applied. Forty-four invertebrate taxa were identified in a community characterized by low diversity, and high abundance of salinity tolerant groups. Some invertebrate metrics showed strong associations with concentrations of majoritarian ions in water, CSLSE and SIWQ. Five invertebrate metrics of richness and diversity, three of assemblage composition and three related to feeding groups displayed the best performance in explaining significant differences among sites. These results reinforce the use of biological assessments of human impacts in saline water bodies. They also enhance the knowledge of wetlands of arid regions, extremely fragile habitats that should be deeply studied and understood at a global scale.

Dual-Core Twisted Photonic Crystal Fiber Salinity Sensor: A Numerical Investigation

The amount of salt dissolved in a body of water is an important factor in determining physical characteristics like the heat capacity of the water. Here, we report a theoretical and numerical investigation on a seawater salinity sensor using a miniaturized fiber-optic probe based on a dual-core photonic crystal fiber (PCF). The sensing mechanism is based on interplay between fiber fundamental mode in the central core and a secondary mode in the water-filled hole of the PCF. Using finite element method analysis with Comsol Multiphysics Software, we show that a spectral sensitivity larger than 5500 nm/RIU can be achieved while varying the salt concentration from 0% to 100%. Furthermore, we demonstrate that the sensitivity for highly saline water bodies can be further improved by applying the permanent twist on the cladding air holes of the fiber. We studied the role of the twist directions and twist rates on the performance of the sensor including sensitivity and the absolute loss value. While the twist does not have any major impact on sensitivity of the sensor for low salinities, our results indicate that twisted PCF has an average higher sensitivity for salt concentrations over 50% and a maximum sensitivity of nearly 7000 nm/RIU is reported around salt concentration of 80%.

Paleolimnological response to climate variability during Late Glacial and Holocene times: A record from Lake Arturo, located in the Fuegian steppe, southern Argentina

Last Glacial Maximum and Holocene environmental conditions are reconstructed from a lacustrine core obtained from Lake Arturo, located in the Fuegian steppe of southern Argentina. Proxies include diatoms, ostracods, plants remains, organic matter content and sedimentological studies, and they suggest that Lake Arturo experienced climate-related variations in the water level, hydrological balance and temporal stability throughout the last 23,200 cal yr BP. The Late Glacial period, which ended about 15,400 cal yr BP, is characterized by a few low-diversity diatom assemblages dominated by benthic and small-celled fragilarioid taxa. Between the Pleistocene-Holocene transition and the mid-Holocene, Lake Arturo was a shallow, fresh-to-brackish lake with relatively high organic productivity. Around 6200 cal yr BP, the diatom Surirella tuberosa replaced Thalassiosira patagonica, and diatom species richness fell to its lowest level in the records. Together with the presence of the ostracod Limnocythere rionegroensis, which lives in ephemeral environments, this suggests that the lake was very shallow and experienced negative hydrological balance, with hydrochemical and biological conditions that were similar to those of today. Data from other sites in southern Tierra de Fuego suggest that, around 5000 cal yr BP until 800 cal yr BP the rainfall increased and the temperature decreased as a result of an intensification of the Southern Westerlies. By that time, the Lake Arturo record indicates the existence of an ephemeral, shallow, highly saline water body. This suggests an antiphase response to the atmospheric circulation pattern between the southern humid forest and the northern steppe during the middle to late Holocene.

Modelling the effect of high level of total dissolved solids (TDS) for the sustainable utilization of brackish groundwater from saline aquifers in Kuwait

Groundwater resources in Kuwait are almost brackish to saline. There is a concern that the shallow aquifers in Kuwait are polluted with high levels of salinity. The brackish groundwater lenses of the utilized aquifers in Kuwait are strategically important for the agricultural and industrial sectors. These lenses float above saline water bodies. It is the aim of this study to simulate the impact of skimming brackish lenses on the vertical movement of saline water in the utilized aquifer. In order to achieve this aim, pumping tests were conducted on the wells of the study area using Tartakovsky–Neuman method. The results showed that the average transmissivity and specific yield are 330 m2/day and 12%, respectively. The results of the pumping tests were fed into a density-dependent flow with solute transport model to simulate the fate of saline water (with TDS values from 10,000 to 43,000 mg/l) in the utilized aquifer under pumping conditions. The modelling results show that controlling the vertical movement of deeper saline water can be achieved by locating the well screen alongside most of the saturated thickness that includes both brackish and saline water bodies. Only the salinity of the area around well W-2 exceeded the limit of 10,000 mg/l when the total pumping rates from all the wells were 6624 m3/day. This means that the sustainable yield of the aquifer in the utilized zone of the study area is about 5746 m3/day (2.1 Mm3/year) after eliminating the pumping rate of well W-2. The elevated final salinity of the pumped water at this well is influenced by the value of the initial salinity of this well, which was high at 9519 mg/l prior to pumping.

A national-scale data set for dissolved carbon and its spatial pattern in lakes and reservoirs across China

A dissolved carbon (DC) data set, including dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC), from 224 lakes (513 stations) and 141 large reservoirs (337 stations) across China is presented in this study. In addition to DC, the data set also includes results for electrical conductivity (EC), total phosphorus (TP), chlorophyll-a and transparency. The impact of trophic status and EC gradient on DC concentration in water bodies are discussed. Results from our investigation indicate that DC in saline (EC > 1000 μS cm−1) water bodies (mean ± S.D, 297.13 ± 356.14 mg L−1, n = 186) are much higher than those in fresh water bodies (79.55 ± 199.34 mg L−1, n = 669). Similarly, eutrophic water bodies (n = 552) exhibited higher DC concentrations than mesotrophic (n = 215) and oligotrophic water bodies (n = 85); DC in lakes (158.445 ± 286.52 mg L−1, n = 513) was significantly higher than DC in reservoirs (37.83 ± 37.53 mg L−1, n = 337). All data used in this investigation is accessible online.

Lithostratigraphy, mineralogy and the boron-bearing brine evolution of DaQaidam Salt Lake in Qaidam Basin since Holocene period, northern Qinghai-Tibet Plateau

Little attention has been paid to the study of sedimentary records from DaQaidam Salt Lake regarding brine evolution and hydro-climate change. Here we report the results of AMS 14C dating and mineralogical investigation on a sediment profile D4 from the south central of perennial saline water-body. The result revealed that pinnoite deposit in the lakebed was formed in early Holocene, the lake underwent three stages of lake-level and brine evolution in Holocene period, which were determined mainly by precipitation-controlled catchment inflow. The mineralogical records also depicted fluctuations in lake level and hydrochemistry on decadal and centennial scales.

Organic geochemical characteristics and organic matter enrichment of mudstones in an Eocene saline lake, Qianjiang Depression, Hubei Province, China

Abstract The Qianjiang Depression is a typical Eocene hypersaline lake basin developing good source rocks in the Qianjiang Formation, which have recently been identified as a potential target for saline lacustrine shale oil exploration. Previous studies have only focused on estimates of source rock potential and reservoir quality. However, studies on organic matter enrichment mechanisms in evaporative environments are limited. Based on organic geochemical and mineralogical data, as well as sedimentological analyses, we researched the factors controlling differences in organic matter enrichment in the basin. The results show that total organic carbon (TOC) contents are closely associated with lithofacies with distinct variations. Three main lithofacies associations (LAs) were identified: (1) glauberite-rich LA1 with medium TOC; (2) carbonate-rich LA2 with high TOC; and (3) anhydrite-rich LA3 with low TOC. The distribution of biomarkers from 14 samples indicate both higher land plants and aquatic organisms were involved in the organic matter accumulations. Combining experimental results on gammacerane/C30 hopane, extended tricyclic terpane ratio (ETR), Sr/Ba, V/Ni, and sedimentary characteristics, we analyzed the sedimentary environments of the three LAs. LA1 was deposited in a salinity stratified waterbody with strong evaporation, LA2 was deposited in a still, stratified deep waterbody, whereas LA3 was deposited in a disturbed, saline waterbody. Sedimentary environments not only controlled the formation of the lithofacies, but also influenced the organic matter sources and preservation. Relatively low salinity, strong anoxic condition without physical disturbance, appropriate nutritional terrigenous material inputs, and algal blooms produced the best organic matter enrichment in the saline lake system.

Management of Seawater Intrusion in Coastal Aquifers: A Review

Seawater intrusion (SWI) is one of the most challenging and widespread environmental problems that threaten the quality and sustainability of fresh groundwater resources in coastal aquifers. The excessive pumping of groundwater, associated with the lack of natural recharge, has exacerbated the SWI problem in arid and semi-arid regions. Therefore, appropriate management strategies should be implemented in coastal aquifers to control the impacts of SWI problems, considering acceptable limits of economic and environmental costs. The management of coastal aquifers involves the identification of an acceptable ultimate landward extent of the saline water body and the calculation of the amount of seaward discharge of freshwater that is necessary to keep the saline–freshwater interface in a seacoast position. This paper presents a comprehensive review of available hydraulic and physical management strategies that can be used to reduce and control SWI in coastal aquifers. Advantages and disadvantages of the different approaches are presented and discussed.

Oviposition and Development of Anopheles coluzzii coetzee and Wilkerson in Salt Water.

Anopheles coluzzii is an important vector of malaria in sub-Saharan Africa particularly of the most dangerous malaria parasite. It completes its life cycle in water and a change in physicochemical properties particularly that of salinity of water may affect egg laying and perhaps the development of eggs to maturity. Studies have shown that climate change may alter the transmission of many vector-borne diseases in different parts of the world and global warming will also raise sea levels which will lead to an increase in saline and brackish water body in coastal areas. This study investigated the salinity tolerance level of An. coluzzii. It involved creation of artificial environments of different salinity gradients using rainwater and sea water and the subsequent exposure of the media to An. coluzzii for laying of eggs and development of larvae to adult. Anopheles coluzzii showed ovipositional preference for less saline media as there was significant negative correlation between number of eggs laid and salinity of oviposition media. Effect of salinity was evident in egg development and larval survival, as no egg hatched in >30% sea water, all L3 larvae died in >40% seawater, and the maximum seawater concentration for L4 survival was 30%. An LC50 of 17.51% (95% CI: 9.31–24.56)% and 23.4% (95% CI: 16.76–22.30)% were calculated for L3 and L4 larvae respectively. Adults emerging from fresh and low saline water of 10% seawater had greater energy reserve than those emerging from 20% and 30% seawater. Increasing salinity did not affect wing length of the emerging adult. Despite the increased stress on larval development, some individuals survived and went on to emerge as adults in conditions that seem to be representative of brackish water. This may imply that an increase in brackish water sites caused by rising sea levels might create more suitable breeding sites for this species.

A glimpse of the prokaryotic diversity of the Large Aral Sea reveals novel extremophilic bacterial and archaeal groups.

During the last five decades, the Aral Sea has gradually changed from a saline water body to a hypersaline lake. Microbial community inhabiting the Aral Sea has been through a succession and continuous adaptation during the last 50 years of increasing salinization, but so far, the microbial diversity has not been explored. Prokaryotic diversity of the Large Aral Sea using cultivation‐independent methods based on determination of environmental 16S rRNA gene sequences revealed a microbial community related to typical marine or (hyper) saline‐adapted Bacteria and Archaea. The archaeal sequences were phylogenetically affiliated with the order Halobacteriales, with a large number of operational taxonomic units constituting a novel cluster in the Haloferacaceae family. Bacterial community analysis indicated a higher diversity with representatives belonging to Proteobacteria, Actinobacteria and Bacteroidetes. Many members of Alphaproteobacteria and Gammaproteobacteria were affiliated with genera like Roseovarius, Idiomarina and Spiribacter which have previously been found in marine or hypersaline waters. The majority of the phylotypes was most closely related to uncultivated organisms and shared less than 97% identity with their closest match in GenBank, indicating a unique community structure in the Large Aral Sea with mostly novel species or genera.

Planktonic indicators of water quality: A case study in the Amacuzac River Basin (State of Morelos, Mexico)

AbstractPlanktonic organisms are good indicators of water quality but are rarely used in Mexican riverine studies in spite of the high level of contamination in these lotic waters. In this study, we focused on the plankton of the river Amacuzac in Mexico and a large saline waterbody, Lake Tequisquitengo, which is located in the Amacuzac river basin. We collected samples at three sites in the River Amacuzac and one at Lake Tequisquitengo from May 2015 to March–April of 2016. We analysed the physicochemical variables, coliform bacteria, and biological oxygen demand levels. We also quantified phytoplankton and zooplankton. Our results indicate that the study sites are mesotrophic with high densities of diatoms and cyanobacteria. Among the zooplankton, the dominant organisms were rotifers. The constancy of planktonic taxa was high in the lake but low in the river. The Descy index ranged from 2.9 to 4.5 in the river and from 4.0 to 5.0 in the lake. The saprobic index shows that the system is β‐mesosaprobic. The species diversity was higher in the river than in the lake. Our study shows that plankton can efficiently be used to evaluate the water quality in rivers and lakes.