Coastal Saline Lakes Research Articles

Protistan community composition in anoxic sediments from three salinity-disparate Japanese lakes

Community composition patterns of benthic protists were investigated in salinity-disparate lakes, including a coastal saline lake (Lake Hiruga), a brackish lake (Lake Suigetsu) and a freshwater lake (Lake Biwa). Samples were collected from the surface layer of anoxic sediment (0–5 cm depth horizon) at each lake; two sets of samples were collected 2 months apart. Sequences of 18S rRNA genes were analysed using high throughput sequencing. We obtained 63,619–389,041 sequences per sample, resulting in 4,331 operational taxonomic units (OTUs) based on 98% similarity. Cluster analysis showed that the community structures between seasons in each lake were similar, while there were marked differences among lakes. Other than photosynthetic organisms, Metazoa and Fungi, 3,018 (70%), 1,132 (26%) and 391 (9%) of protistan OTUs were obtained from lakes Biwa, Hiruga and Suigetsu, respectively. Taxonomic analysis showed 23 OTUs (5.3%) were common to the three lakes, and were composed of 19 Alveolata-, three Stramenopiles- and one unclassified-related taxa. Our results suggest that salinity is an important environmental variable that determines community composition of protists in anoxic sediments in lakes.

Unstable convection flow as a controlling process of increasing salinity in the saline lake coastal aquifers: case of Maharlu Lake coastal aquifer

Deterioration of freshwater aquifers adjacent to saline lakes is a serious environmental and water resources management problem. Generally, different phenomena including saltwater intrusion, upconing, free and forced convection flow can lead to the salinization of fresh aquifers in the vicinity of saline lakes. The severity of this problem depends on hydrogeological and hydrogeochemical conditions of coastal saline lake aquifers. Accordingly, Maharlu Lake in the southeast of Shiraz plain is one of these saline lakes and has an important impact on its adjacent fresh aquifers so that the salinity of these aquifers has increased in recent years. Since the lake has special conditions such as very flat and low permeable floor and variable water level fluctuation during a year, with the onset of the rainy season after a long-term well pumping in the adjacent aquifer, the lake water covers a wide extent of the lake area in a short time. Then, because of the higher permeability of the surface of the lake in its southeast margin, conditions for convection flow are provided there. In this study, salinity distribution in one of the aquifers (Bokat aquifer) in the southeast of the lake is investigated using resistivity tomography along several profiles. Interpretation of inverse models of these profiles showed that convection flow is an important process in increasing the salinity of fresh aquifer. Comparison of the results of geo-tomography sections with convection index map of the Bokat aquifer showed that getting closer to the lake, free convection flow becomes the dominant process in the salinity distribution. In addition, in farther distances relative to the lake, due to increasing the pumping rate of the extraction wells, forced convection flow is an important process.

Arc GIS Based Interpretation of Surface Sediment Heavy Metals Near Coastal Area of District Badin, Sindh, Pakistan

The present study investigates heavy metal contamination of sediments of the surface drains, lakes and lagoons of coastal district Badin. The accumulation of industrial, municipal waste water, pumped saline water and agricultural runoff through left bank outfall drain (LBOD) and other linking drains in the coastal lines of Badin, Sindh, Pakistan, have disturbed the environmental ecology of the area. The heavy metal characteristics of sediments were analyzed, i.e. ionic and molecular species of Hg,Ni, Fe, Cd, Pb, Cr, Co, Cu, Mn, and Zn. Arc GIS application was used for mapping of the studied area. The obtained results were represented by GIS based maps, with graduated colored circles. A total of 31 sediment samples were taken from drains, lakes and lagoons of coastal areas. The average results, analyzed for heavy metals, were found as Hg(mg/kg) 0.2032 ±0.173, Ni (mg/kg)1.455 ±1.449,Cd (Not Detected), Zn(mg/kg)2.789 ± 0.865, Cu(mg/kg)0.3050 ±0.3355, Fe(mg/kg)71.175±1.610, Mn (mg/kg)7.375±1.848, Co (mg/kg) 0.0548 ±0.0634,Pb(mg/kg)0.216 ± .114,Cr(mg/kg)0.7054 ±0.6949.The obtained results indicated that pollution of heavy metal concentration in surface sediments of lakes , lagoons, and drains near coastal lines of Badin Sindh, posed a serious question . The main contaminating sources in the area are LBOD and other link drains, carrier of industrial effluents of different districts. Poor infrastructure of LBOD facilitates backward flow of contaminated sea tidal water towards coastal saline lakes, also adds in sediment pollution.

Redescription of Rhizodomus tagatzi (Ciliophora: Spirotrichea: Tintinnida), Based on Morphology and Small Subunit Ribosomal RNA Gene Sequence

Herein, we redescribe a tintinnid ciliate that is most commonly known as Tintinnopsis corniger Hada, 1964; but it has been described several times with different names, specifically Tintinnopsis nudicauda Paulmier, 1997 and Rhizodomus tagatzi Strelkow & Wirketis, 1950. Neotype material was collected from the water column of the coastal saline Lake Faro, a meromictic basin connected to the Straits of Messina, Central Mediterranean. The Lake Faro population is characterized by a hyaline or sparsely agglomerated lorica, which made it possible to observe in detail the basal layer structure, usually concealed by abundant incrusting particles. Along with an improved description of the lorica, we provide novel information, such as the general zooid morphology, the ciliary pattern, and the small subunit rRNA (SSU rRNA) gene sequence. Our phylogenetic analysis, based on the SSU rRNA, groups this species with Tintinnopsis radix, while the first taxonomic study designated it as R. tagatzi, introducing a new genus due to peculiarities in lorica morphology. We conclude that the species should be known as R. tagatzi, the senior synonym for the species. However, we do not transfer any other species to this genus, despite strong molecular similarities. Although it is obvious that the genus Tintinnopsis is in need of a thorough revision, current molecular and cytological information for this genus is too sparse, and the type species has not yet been redescribed with modern methods.

A survey of the benthic aquatic flora in transitional water systems of Greece and Cyprus (Mediterranean Sea)

Seasonal samples of macrophytes were collected from April 2003 to May 2010 from the most important transitional water systems of western Greece (nine coastal lagoons) and Cyprus (two coastal saline lakes, Akrotiri and Alyki Larnaca’s). Our aim was to summarize, list and provide a full inventory of benthic aquatic flora recorded in these transitional water systems. The 60 taxa found belonged to five phyla, viz., Rhodophyta, Ochrophyta, Chlorophyta, Streptophyta and Magnoliophyta. There were 56 taxa in Greek lagoons and 16 in Cypriot water bodies. Many macroalgal species recorded in these environments form attached and unattached assemblages and play integral roles in the quality status of transitional water systems. The rare charophytes (Streptophyta) Chara tenuispina and C. hispida f. corfuensis are newly recorded for the Greek study area. In Cyprus, we found four species of charophytes (Chara aspera, C. canescens, C. vulgaris and Lamprothamnium papulosum) and two species of spermatophytes (Magnoliophyta): Althenia filiformis and Potamogeton pectinatus, which are new records for the island. Najas marina ssp. armata, P. pussilus, and Zannichelia pallustris ssp. pedicellata are new records for the study areas on Cyprus.

10.1007/s11489-008-3005-9

Although it has previously been considered to be a rare phenomenon, this paper provides evidence of eight occurrences of Atlantic cod in northern coastal saline lakes in Arctic Canada, Greenland, Norway, and Russia. Historic and current habitat features that are necessary for Atlantic cod to colonize and persist in Arctic meromictic lakes are discussed. Data analyses confirm that the persistence of Atlantic cod in Arctic lakes is a recurrent phenomenon, and these populations represent an important component of intraspecific biodiversity.

The isolation of Atlantic cod, Gadus morhua (Gadiformes), populations in Northern Meromictic lakes—A recurrent arctic phenomenon

Although it has previously been considered to be a rare phenomenon, this paper provides evidence of eight occurrences of Atlantic cod in northern coastal saline lakes in Arctic Canada, Greenland, Norway, and Russia. Historic and current habitat features that are necessary for Atlantic cod to colonize and persist in Arctic meromictic lakes are discussed. Data analyses confirm that the persistence of Atlantic cod in Arctic lakes is a recurrent phenomenon, and these populations represent an important component of intraspecific biodiversity.

Sampling patchily distributed taxa: a case study using cost–benefit analyses for sponges and ascidians in coastal lakes of New South Wales, Australia

Estuaries worldwide are under increasing threat from human impacts. Because much of their fauna remains unstudied and in many cases undescribed, these systems present real challenges for effective management. In eastern Australia the study of estuarine fauna is often further compli- cated by its patchy distributions. This is particularly the case for assemblages of sessile invertebrates in coastal saline lakes. This study quantified distributions of sponges and ascidians at a hierarchy of spatial scales in the seagrass meadows of 2 coastal saline lakes in New South Wales, Australia. Nine species of sponge, many of which were undescribed, and 3 species of ascidians were found. Nested analyses of variance were used to identify spatial scales at which variation was significant. Most sponges and ascidians were very patchily distributed at a range of spatial scales from 10s of metres up to 100s of kilometres. The composition of assemblages differed greatly between the 2 lakes. In addition, unlike other published examples of cost-benefit analyses, in the present study very few taxa were widespread over the larger spatial scales. Cost-benefit analyses done to determine the optimal sampling design for future experiments revealed inclusion of patchily distributed taxa in analyses could improve the overall precision of sampling.

Phytoplankton dynamics in a coastal saline lake (SE-Portugal)

Abstract The aim of this study was to characterise phytoplankton dynamics in a coastal saline lake, pinpointing putative biotic and abiotic regulatory variables of its succession and productivity. Between February and September 1998, samples for the analysis of physical, chemical and biological variables were taken fortnightly (except in February and April). The phytoplankton community showed three distinct periods of evolution. The first period (February-March) was characterised by a chroococoid non-colonial cyanobacteria bloom (maximum abundance, 4.3 × 10 9 cells l –1 ) and also by its decaying. Long water residence and/or nitrogen limitation might have allowed cyanobacteria dominance; while its decaying could be associated to predation by aplastidic nanoflagellates and/or to the beginning of periodical partial renewal of lake water with water proceeding from an adjacent coastal lagoon (Ria Formosa). The second period (April-early August) can be differentiated, from the previous, by reduced abundances of phytoplankton (minimum abundance, 5.7 × 10 6 cells l –1 ) and plastidic nanoflagellates dominance. The overall low nutrient concentrations, likely as a consequence of periodical partial water renewal, could explain these results. In the last period (late August-September), increased phytoplankton abundance and the development of a diatom and mixotrophic dinoflagellate bloom was probably the result of a sudden increase in nutrient levels, occurring after a period of intense precipitation. In consequence, primary production reached a maximum value of 1367 mg C m –3 h –1 ; 36 times higher than a maximum value previously reported for Ria Formosa.

Geological setting of two quaternary footprint sites, western South Australia

A variety of trace fossils including human, avian and macropodid footprints are preserved in two coastal settings of different ages near Clare Bay, South Australia. Macropodid and other tracks occur in laminated littoral sediments of Late Pleistocene age (ca. 110 000 years BP). They are preserved beneath a former prograding coastal fore‐dune complex now being exposed by shoreline erosion and regression. Human footprints, together with tracks of emus, kangaroos and wallabies, are present a few kilometres inland on the margin of a coastal saline lake. They originated about 5000 years ago, when soft dolomitic and calcitic marls formed from groundwater seepage and evaporation around gypseous lake margins. Preservation resulted from subsequent lithificat ion of the marl. The footprints have been subject to continuing exposure since formation but are remarkably well preserved.

Lake Thetis, Western Australia: and example of Saline Lake Sedimentation dominated by Benthic Microbial Processes

Lake Thetis is a saline coastal lake in south-western Australia, a region of winter rainfall and summer drought. The lake demonstrates the close relationships between environmental variation and the nature of resident benthic microbial communities. Crenulate cyanobacterial mats occur in the low-lying areas adjacent to the lake. Lithified stromatolites with patches of living coccoid cyanobacterial mat characterize the littoral area, whereas a thick flocculent mat composed of phototrophic prokaryotes (principally purple sulfur bacteria) and diatoms has accumulated in the central lake basin. Lake Thetis is distinguished from other coastal saline lakes by the presence of the unusual flocculent mat and by the juxtaposition of this microbial community to the marginal lithified stromatolites. Further, some of the latter exhibit internal digitate columnar branching which, though common in Precambrian examples, is rare in modern environments.

Dichotomicrobium thermohalophilum, gen. nov., spec, nov., Budding Prosthecate Bacteria from the Solar Lake (Sinai) and Some Related Strains

Summary Ten strains of budding bacteria with dichotomously branching hyphae have been isolated from various depths of the Solar Lake (Sinai, near Elat). Three additional strains of similar bacteria came from a shallow coastal saline lake in Brazil. All of these 13 strains had a similar morphology: nearly tetrahedral mother cells produced up to 4 hyphae at the tips of which non-motile buds were formed. Dichotomous branching of the hyphae often resulted in the formation of chains or even nets. Contrary to all other budding, hyphal bacteria, these isolates contained poly-β-hydroxybutyrate granules in their hyphae. Liquid cultures showed reddish pigmentation (carotenoids), and colonies on solid media were dark brown with fuzzy edges. The organisms stained Gram-negative. All strains required yeast extract for growth, and all strains were moderately thermophilic and halotolerant. The maximum temperature tolerated for growth was between 52 and 65°C. The 13 strains were strictly aerobic, heterotrophic, and they utilized a few organic acids, notably those of the tricarboxylic acid cycle (malate, succinate). Growth with sugars was poor and variable. A few amino acids were utilized for growth. Inorganic nitrogen sources did not support growth, but amino acids, especially glutamate, arginin, leucin, methionin and cystein were utilized by some strains. Excellent growth occurred on sheep blood agar, but there was no hemolysis. Growth was significantly inhibited by 1–10 μg/ml of penicillin G and some other antibiotics. All 13 of these strains were sufficiently alike to include them in a new genus, and the ten strains from the Solar Lake are considered to represent one species. The genus name, Dichotomicrobium gen. nov. is proposed, with the type species, D. thermohalophilum n. sp. The type strain, IFAM 954, had 64 mol% G+C and it has been deposited in the Deutsche Kultursammlung fur Mikroorganismen (DSM 5002).

Upper Triassic to Lower Cretaceous continental and coastal saline lake evaporites inthe Atacama region of northern Chile

AbstractEvaporites within Upper Triassic to Lower Cretaceous sequences in the Atacama region of northern Chile are interpreted as the deposits of continental and coastal saline lakes. Halite casts and finely laminated calcareous evaporites, intercalated with alluvial and fluvial sediments, are probably playa lake deposits. These continental evaporites have been recognized in Upper Triassic alluvial sediments (Cifuncho Formation), in Upper Triassic–Lower Jurassic braided river deposits (basal unit of the Pan de Azúcar Formation), and within a sequence of Lower Cretaceous aeolian, alluvial and playa lake mudflat sediments (Quebrada Monardes Formation). Lower Cretaceous evaporites between marine limestones (Lautaro Formation) and continental redbeds (Quebrada Monardes Formation) were probably deposited in coastal saline lagoons, produced during a regionally extensive marine regression.These sequences, and other similar successions in northern Chile, provide a record of almost continuous evaporite deposition, and hence of arid to semi-arid conditions, since Upper Triassic times. These conditions were primarily the result of a constant latitudinal position within the subtropical zone. A contributary factor was the geographical position of the area, initially on the west coast of Gondwanaland and subsequently on the coast of South America, with cold, northward-flowing ocean currents and offshore winds.

Water chemistry of the coastal saline lakes of the Clifton-Preston Lakeland system, south-western Australia, and its influence on stromatolite formation

The water chemistry of Lake Clifton, the adjacent lakes and the regional ground water was investigated to aid in the elucidation of the factors responsible for the restriction of living stromatolites to Lake Clifton. The ionic composition of water in the lakes is proportionally similar to sea water, but the ground water is enriched in calcium and bicarbonate and is of lower salinity (1-2 g I-1). The salinities of the lakes ranged from 7 to 369 g l-1 during 1984 but, in contrast to the other lakes, Clifton remained less saline than sea water throughout the year. Ground waters from an unconfined aquifer on the eastern shore made a large contribution to the annual lake water budget of Lake Clifton, maintaining lake water salinity at less than 35 g l-1 and modifying the chemical composition of the sediment-water interface where stromatolites form. Living, lithified stromatolites occur along the eastern shore of Lake Clifton. They are formed by a benthic microbial community rich in Scytonema. The Stromatolites co-exist with an abundant metazoan fauna, but do not appear to be limited by grazing. Clearly defined zones of ground-water intrusion were found along the eastern foreshore and areas of differential ground-water discharge were associated with morphologically distinctive stromatolites. Occurrence of stromatolites and regions of ground-water discharge in Lake Clifton are consistently associated. It is suggested that the intruding ground waters in Lake Clifton provide a chemical environment conducive to the formation of calcified stromatolites.

Osmotic adaptations of charophyte algae in the Coorong, South Australia and other Australian lakes

Lamprothamnium is found in salinities varying from nearly fresh to twice sea water in coastal saline lakes in South Australia, Victoria, and New South Wales. It maintains its turgor (ΔP≅ΔII) approximately constant over this range, varying internal osmotic pressure by altering KCl concentration (although at the highest salinity, Na+ concentration became more important). The ability to regulate turgor with alterations in salinity is wide-spread in marine algae, but has not been reported for the freshwater charophytes. Lamprothamnium is also unusual among algae and particularly among charophytes in having a high concentration of sucrose (up to 300 mM) in the vacuole. Vacuolar concentration is not correlated with salinity and its adaptive significance is not known, although in the cytoplasm sucrose may play a significant role in osmotic adaptation.