Ancient Lake Research Articles

Formation mechanism of carbonates in the lacustrine muddy shale and it implication for shale oil and gas: A case study of source rocks in Member 4 and Member 3 of Shahejie Formation, Dongying sag

Through analysis of microscopic characteristics, mineral components, elements and isotopes, the genetic mechanism of carbonates in the deep lacustrine source rocks in the upper submember of Member 4 and lower submember of Member 3 of Shahejie Formation in Dongying sag, is well investigated. The results show that four types of carbonates in the deep lake, i.e., lenticular coarse crystalline carbonate, lamellar micro-fine crystalline carbonate, lamellar cryptocrystalline carbonate and massive cryptocrystalline carbonate. Of which, the lenticular coarse crystalline carbonate is formed by diagenetic recrystallization. For the lamellar micro-fine crystalline carbonate and the lamellar cryptocrystalline carbonate, through the alga photosynthesis, the carbon dioxide (CO2) is constantly extracted from water, thus the concentration of CO3−2 ion in water increases, and then the CO3−2 ion reacts with Ca2+ ion in lake water surface to form the carbonates; the saline water environment is favorable for preservation of carbonate particles which mostly occur in lamellar micro-fine crystalline; in the brackish water environment, the water is deep, and the carbonate crystalline beneath the carbonate compensation depth surface is usually is dissolved, and most of lamellar cryptocrystalline are preserved. The massive cryptocrystalline carbonate is formed by the sedimentary carbonate which transport from shallow water to deep water by gravity flow. To some extent, the carbonates control reservoir property and compressibility of muddy shale in the upper submember of Member 4 and lower submember of Member 3 of Shahejie Formation in Dongying sag, and provide important information for reconstruction of sedimentary environment of the ancient lake.

Genetic diversity of Microsporidia in the circulatory system of endemic amphipods from different locations and depths of ancient Lake Baikal.

Endemic amphipods (Amphipoda, Crustacea) of the most ancient and large freshwater Lake Baikal (Siberia, Russia) are a highly diverse group comprising >15% of all known species of continental amphipods. The extensive endemic biodiversity of Baikal amphipods provides the unique opportunity to study interactions and possible coevolution of this group and their parasites, such as Microsporidia. In this study, we investigated microsporidian diversity in the circulatory system of 22 endemic species of amphipods inhabiting littoral, sublittoral and deep-water zones in all three basins of Lake Baikal. Using molecular genetic techniques, we found microsporidian DNA in two littoral (Eulimnogammarus verrucosus, Eulimnogammarus cyaneus), two littoral/sublittoral (Pallasea cancellus, Eulimnogammarus marituji) and two sublittoral/deep-water (Acanthogammarus lappaceus longispinus, Acanthogammarus victorii maculosus) endemic species. Twenty sequences of the small subunit ribosomal (SSU) rDNA were obtained from the haemolymph of the six endemic amphipod species sampled from 0–60 m depths at the Southern Lake Baikal’s basin (only the Western shore) and at the Central Baikal. They form clusters with similarity to Enterocytospora, Cucumispora, Dictyocoela, and several unassigned Microsporidia sequences, respectively. Our sequence data show similarity to previously identified microsporidian DNA from inhabitants of both Lake Baikal and other water reservoirs. The results of our study suggest that the genetic diversity of Microsporidia in haemolymph of endemic amphipods from Lake Baikal does not correlate with host species, geographic location or depth factors but is homogeneously diverse.

A Putative Species Flock in the Diatom GenusGomphonemaEhrenberg (Bacillariophyta: Gomphonemataceae) from Lake Baikal, Russia: Description of Six New Species Similar toG. ventricosumW. Gregory

We describe as new to science six new species of the diatom genus Gomphonema Ehrenberg from Lake Baikal, based on light and scanning electron microscope observations. The six species are morphologically similar to G. ventricosum, a northern European taxon known mostly from Scotland, Scandinavia and other Baltic countries, though it has been recognized also from North America. The six species are similar to G. ventricosum W. Gregory in the structure of the external occlusions over the areolae. The species also have prominent septa and pseudosepta, which distinguishes them from other species of the genus. They are distinguished from one another in the shapes and sizes of the valves. This group of closely related species may correspond to a species flock, a phenomenon in freshwater diatoms that is known from ancient lakes and flowing water systems. Further research is needed to confirm the monophyly of this group, and either support or challenge the idea of them representing a species flock.

Recent ecological change in ancient lakes

AbstractAncient 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.

History and conservation of Tunisia's largest freshwater wetland: Garâa Sejenane

The Garâa Sejenane is an ancient lake in northern Tunisia that currently houses a mosaic of temporary wetlands. Comparison of modern pollen data and field vegetation surveys shows both a weak regional pollen signal and the homogenization of pollen assemblages at the scale of the garâa. Despite a hiatus between 19,000 and 2230 cal. BP, fossil pollen analyses provide the first Tunisian LGM record and attest to the ancient origin of the lake, which housed some taxa still present locally in the 1950s. The originality of the Pleniglacial surrounding landscape dominated by a juniper steppe contrasted with the mountain conifer forests in Kroumiria. Lastly, analyses of aerial photographs (1948, 1962, 1984), recent satellite photographs and previous botanical descriptions reveal that the lake has been drying since 1960 because of important anthropogenic activities (drainage, groundwater pumping, cultivation, grazing…). These disturbances have generated profound changes in hydrophytic plant communities (fragmentation, diversity loss, introduction of invasive species…) that are likely to threaten their long-term survival.

Clay mineral diversity and abundance in sedimentary rocks of Gale crater, Mars.

Clay minerals provide indicators of the evolution of aqueous conditions and possible habitats for life on ancient Mars. Analyses by the Mars Science Laboratory rover Curiosity show that ~3.5-billion year (Ga) fluvio-lacustrine mudstones in Gale crater contain up to ~28 weight % (wt %) clay minerals. We demonstrate that the species of clay minerals deduced from x-ray diffraction and evolved gas analysis show a strong paleoenvironmental dependency. While perennial lake mudstones are characterized by Fe-saponite, we find that stratigraphic intervals associated with episodic lake drying contain Al-rich, Fe3+-bearing dioctahedral smectite, with minor (3 wt %) quantities of ferripyrophyllite, interpreted as wind-blown detritus, found in candidate aeolian deposits. Our results suggest that dioctahedral smectite formed via near-surface chemical weathering driven by fluctuations in lake level and atmospheric infiltration, a process leading to the redistribution of nutrients and potentially influencing the cycling of gases that help regulate climate.

Forgotten for decades: Lake Lanao and the genetic assessment of its mollusc diversity

Lake Lanao on Mindanao island is the largest freshwater lake in the Philippines and may represent one of the few ancient lakes in Southeast Asia. This lake’s fauna is best known for its endemic cyprinid fishes that have been nearly driven to extinction through various anthropogenic actions. In contrast, only little is known about Lake Lanao’s invertebrate fauna and its placement within related Southeast Asian taxa. We here focus on the diversity in freshwater molluscs, particularly the morphologically diverse viviparid gastropods, and provide first genetic insights into this group in order to test whether the morphological variability observed is also reflected by corresponding genetic variation. Mitochondrial sequence data indicate that these viviparids form a monophyletic group comprising morphologically distinct and partly genetically different (morpho)species. Both the high diversity found in cyprinid fishes and viviparid gastropods together with the geological and tectonic evolution of Mindanao suggest that Lake Lanao may have originated more than 100,000 years ago and is thus indeed an ancient lake. However, its fauna is under continuous threat not least from the introduction of non-native species, and the development and implementation of sustainable conservation strategies is direly needed.

Spatial patterns of diatom diversity and community structure in ancient Lake Ohrid

The extraordinary diversity in long-lived lakes is largely driven by distinct eco-evolutionary processes. With their unique biota and numerous endemic taxa, these lakes are key settings for fundamental studies related to ecology, diversity, and evolution. Here, we test how the environment shapes diatom diversity and community patterns over space in ancient Lake Ohrid. By applying Bray–Curtis similarity analyses of diatom community data, including widespread and endemic taxa, we identified two major zones: littoral and sublittoral. The latter one is being characterized with higher endemic diversity. The α and β diatom diversity and community distribution in the northern and eastern part of the lake are influenced by the presence of vertical (bathymetrical) and horizontal barriers. The zonation of the diatom communities appears driven by two large-scale factors: (i) water depth, and (ii) water chemistry, primarily, the concentration of total phosphorus, nitrogen ammonia, and conductivity. Both drivers appear to equally influence diatom diversity and community patterns. We present initial data on diatom–environment relations, where the results support earlier ecological studies emphasizing the relevance of ongoing human-induced eutrophication in the northern lake area. This study provides background information on the role of the environment in structuring contemporary diatom diversity. However, future research needs to focus on the biotic component including species competition in order to reveal the mechanisms driving spatial community dynamics in Lake Ohrid.

In search of Pleistocene remains at the Gates of Europe: Directed surface survey of the Megalopolis Basin (Greece)

The PaGE Project survey of the Megalopolis Basin (Arcadia, Greece), conducted in 2012–2013 over a period of two field seasons, was an intensive, target-oriented surface survey of Pleistocene sediments. Implementing a modified version of field methods applied in our survey of cave systems and Pleistocene cave sediments, the main goal of this systematic research focused on the identification of intact stratified remains from either stratigraphic sections or on remnants of exposed ancient surfaces. The project area consisted of the active open-cast lignite mine of Megalopolis, where access to recently exposed sections were abundant, and of the alluvial fans in the surrounding uplands, where hominins exploited the commanding views of the ancient lake. This paper presents the survey results and applied field methods for conducting archaeological research within the remnants of an Early to Middle Pleistocene ancient lake system. The project succeeded in identifying at least five surface and stratified sites, the latter including the Lower Paleolithic remains of Marathousa-1. This site is currently under investigation, but has already yielded the oldest chronometrically dated archaeological remains in Greece. Therefore, PaGE has not only managed to place mainland Greece on the Lower Paleolithic map of Europe, but has also successfully tested a methodological corpus for survey research targeting the earliest phases of the Paleolithic period in a Mediterranean landscape.

Compound-specific δD and its hydrological and environmental implication in the lakes on the Tibetan Plateau

The hydrogen isotopic composition ( δ D) of n -alkanes in lacustrine sediments is widely used in palaeoenvironmental studies, but the heterogeneous origins and relative contributions of these lipids provide challenges for the interpretation of the increasing dataset as an environment and climatic proxy. We systematically investigated n -alkane δ D values from 51 submerged plants (39 Potamogeton , 1 Myriophyllum , and 11 Ruppia ), 13 algae (5 Chara , 3 Cladophora , and 5 Spirogyra ) and 20 terrestrial plants (10 grasses and 10 shrubs) in and around 15 lakes on the Tibetan Plateau. Our results demonstrate that δ D values of C29 n -alkane are correlated significantly with the lake water δ D values both for algae ( R 2=0.85, p n =9) and submerged plants( R 2=0.90, p n =25), indicating that δ D values of these algae and submerged plants reflect the δ D variation of lake water. We find that apparent hydrogen isotope fractionation factors between individual n -alkanes and water ( e a/w) are not constant among different algae and submerged plants, as well as in a single genus under different liminological conditions, indicating that the biosynthesis or environmental conditions (e.g. salinity) may affect their δ D values. The δ D values of submerged plant Ruppia in the Xiligou Lake (a closed lake) are significant enriched in D than those of terrestrial grasses around the lake (one-way ANOVA, p Chara in the Keluke Lake (an open lake) display similar δ D values with grasses around the lake (one-way ANOVA, p =0.826>0.05), suggesting that the n -alkane δ D values of the algae and submerged plants record the signal of D enrichment in lake water relative to precipitation only in closed lakes in arid and semi-arid area. For each algae and submerged plant sample, we find uniformed δ D values of different chain length n -alkanes, implying that, in combination with other proxies such as Paq and Average Chain Length, the offset between the δ D values of different chain length n -alkanes can help determine the source of sedimentary n -alkanes as well as inferring the hydrological characteristics of an ancient lake basin (open vs closed lake).

A new, large species of Gomphonema Ehrenberg from ancient Lake Matano, Indonesia

A large species of the diatom genus Gomphonema Ehrenberg, G. matanensis sp. nov., is described as new to science from ancient Lake Matano, Indonesia. Light and scanning electron microscopic observations of the valve morphology of this species are presented. The morphology of this species is similar to other large species that have ovoid areolar openings without external flaps or occlusions, such as G. gomphopleuroides Amossé ex Kociolek, Glushchenko & Kulikovskiy and members of the G. kaznakowi species complex, both known from Southeast Asia. This species has the special features of bi- and triradiate siliceous growths at the valve mantle junction, continuing onto the mantle. Though an analysis of the phylogenetic relationships of the diatom genus Gomphonema is currently wanting, it would appear that gigantism occurred several times within the genus.

Climate and environment in southwest Sweden 15.5–11.3 cal. ka BP

Lake sedimentary records that allow documentation of the distinct climatic and environmental shifts during the early part of the Last Termination are scarce for northern Europe. This multi‐proxy study of the sediments of Atteköpsmosse, southwest Sweden, therefore fills an important gap and provides detailed information regarding past hydroclimatic conditions and local environmental responses to climatic shifts. Lake infilling started c. 15.5 cal. ka BP, but low aquatic productivity, cold summer lake water temperatures, unstable catchments, and scarce herb and shrub vegetation prevailed until c. 14.7–14.5 cal. ka BP. Inflow of warmer air masses and higher July air temperatures favoured a rise in aquatic productivity and lake water summer temperatures, and the establishment of a diverse herb, shrub and dwarf shrub vegetation, which also included tree birch c. 14.5 cal. ka BP. Freshening of the moisture source region c. 13.7–13.6 cal. ka BP does not seem to have had a large impact on the ancient lake and its catchment, as lake aquatic productivity increased further and lake water summer temperatures and minimum mean July air temperatures remained around 12–14 °C. In contrast, further freshening of the moisture source region c. 13 cal. ka BP triggered a decrease in lake productivity, drier conditions and lower lake water summer temperatures. Macroscopic finds of tree Betula and Pinus sylvestris at 13–12.8 cal. ka BP demonstrate the presence of these trees in the lake's catchment. The transition into the Holocene (11.6–11.5 cal. ka BP) is marked by a change in chironomid assemblages and by a rise in lake water summer temperatures and aquatic productivity. These changes were followed by the re‐establishment of a diverse aquatic and terrestrial vegetation, including tree birch and Pinus sylvestris at 11.4 cal. ka BP.

The Hyalella (Crustacea: Amphipoda) species cloud of the ancient Lake Titicaca originated from multiple colonizations

Ancient lakes are renowned for their exceptional diversity of endemic species. As model systems for the study of sympatric speciation, it is necessary to understand whether a given hypothesized species flock is of monophyletic or polyphyletic origin. Here, we present the first molecular characterization of the Hyalella (Crustacea: Amphipoda) species complex of Lake Titicaca, using COI and 28S DNA sequences, including samples from the connected Small and Large Lakes that comprise Lake Titicaca as well as from a broader survey of southern South American sites. At least five evolutionarily distant lineages are present within Lake Titicaca, which were estimated to have diverged from one another 12–20 MYA. These major lineages are dispersed throughout the broader South American Hyalella phylogeny, with each lineage representing at least one independent colonization of the lake. Moreover, complex genetic relationships are revealed between Lake Titicaca individuals and those from surrounding water bodies, which may be explained by repeated dispersal into and out of the lake, combined with parallel intralacustrine diversification within two separate clades. Although further work in deeper waters will be required to determine the number of species present and modes of diversification, our results strongly indicate that this amphipod species cloud is polyphyletic with a complex geographic history.

Groundwater contamination by sewage causes benthic algal outbreaks in the littoral zone of Lake Baikal (East Siberia)

Abstract Lake Baikal, an ancient lake in Siberia, contains more endemic species than any other lake in the world with most of them residing in the benthic littoral zone. Explosive growth of benthic Spirogyra, a filamentous green alga, began approximately in 2011 in localized coastal areas, with the most severe examples occurring near coastal towns that lack a wastewater treatment facility or have a malfunctioning system. At other sites (small settlements, harbors), however, the cause of its excess growth is less obvious. Multiple hypotheses have been offered including lake level fluctuations, climate warming, a relaxation of grazing pressure, and coastal eutrophication. We assessed these hypotheses using data on historical lake levels, water temperature, the spatial-temporal distribution of Spirogyra along inhabited and non-inhabited shorelines, and measurements of fecal coliform bacteria and nutrients in ground water, interstitial water, and lake water. These data suggest that groundwater contamination is the primary cause of coastal eutrophication. Most houses and buildings in small settlements around Lake Baikal lack septic tanks but use unlined cesspools to collect human waste. This untreated human waste enters groundwater via passive filtration through permeable soils and flows to the coastal zone where it drives excess growth of Spirogyra. Remediation — including installation of septic systems, modernization of existing sewage treatment plants in coastal towns, and the adoption of non-phosphate containing detergents — as well as a reconsideration of the federal monitoring system regarding the coastal zone is urgently needed to protect this extraordinary lake.

Punctuated changes in the morphology of an endemic diatom from Lake Titicaca

AbstractHigh levels of biodiversity and endemism in ancient lakes have motivated research on evolutionary processes in these systems. Drill-core records from Lake Titicaca (Bolivia, Peru), an ancient lake in the high-elevation Altiplano, record the history of climate, landscape dynamics, and diatom evolution. That record was used to examine the patterns and drivers of morphological evolution of an endemic species complex of diatoms in the lake, theCyclostephanos andinuscomplex. In an attempt to delineate species within the complex based on morphology, no discernible evidence was found for species separation based on an ordination analysis of multiple characters, but multiple populations were detected based on the distribution of valve size in individual samples. Likelihood modeling of phyletic evolution showed that size evolved through punctuated change. Correlation of size trends with environmental variables indicates thatC. andinussize responded to regional environmental change driven by global processes that influenced Lake Titicaca by affecting lake level and thermal stratification.

Multi-proxy indicators in a Pontocaspian system: a depth transect of surface sediment in the SE Caspian Sea

The response of large water-bodies to global change in terms of ecosystem services and economical value is a major concern. The Caspian Sea, the world’s largest enclosed water-body, has a poorly-known water-level history, but observed changes are a hundred times faster than recent global sea-level rise. This ancient lake, characterised by brackish waters, is rich in endemic species; some of them have spread to similar environments worldwide. However, the ecology of Pontocaspian species remains poorly understood and must be studied in their original habitat. This work aims at improving the capacity to reconstruct Quaternary environments of the Pontocaspian region and to provide a benchmark for biodiversity turnover studies. A transect of surface sediment across a wide shelf was subjected to multidisciplinary analyses: stable isotopes, pollen, dinocysts, diatoms, foraminifers, ostracods and molluscs and vertical oceanographic profiles. Three depositional environments with characteristic communities were found: shore face, shelf and slope. Invasion impact was strongly felt by the molluscs. All biota groups, except diatoms, reflected high endemism. The radiocarbon reservoir effect is highlighted in differential 14C ages for different groups. Understanding such discrepancies require detailed insight into reworking processes. Tephra presence in the sediment shows a potential for tephrochronology. Stable isotope ratios in ostracods appear to reflect temperature depth gradients. Our results provide a baseline for calibrating proxy data to the present Pontocaspian environment.

First report of Atyaephyra thyamisensis Christodoulou, Antoniou, Magoulas & Koukouras, 2012 (Decapoda, Caridea, Atyidae) from Albania and the Republic of Macedonia confirmed by DNA barcodes

Abstract The genus Atyaephyra de Brito Capello, 1867 consists of seven species, which are distributed in Europe, Asia Minor and northern Africa. Four of them occur on the Balkan Peninsula, which is known as one of the global diversity and endemism hotspots for freshwater fauna. Atyaephyra thyamisensis Christodoulou, Antoniou, Magoulas & Koukouras, 2012 has been known from Greek mainland and is considered as endemic to the Ionian region. Herewith we report the first finding of this species from the Adriatic region, i.e., Albania and Republic of Macedonia, including the ancient Lake Prespa, and we provide new localities from Greece. Given the subtle morphological features differing this species from other congeners, we support our findings with DNA barcodes.

Antichi riti purificatori dell'Italia preromana: il caso del santuario di Mefitis nella valle d'Ansanto

The valley of Ansanto, Irpinia, is an impressive place with fascinating geophysical characteristics and still displaying volcanic activity: the Mefite of Rocca San Felice is all that remains today of an ancient lake inside a crater, where today dangerous sulphurous springs still burst out with explosive force. This was the location of the sanctuary of Mephitis, the peaceful italic deity protector of herds and trade. Founded by the Hirpini on the cattle drovers’ route from the higher mountain pastures to the lower pastures, it was an important centre of worship for wayfarers from the 6th century BC to the 4rd century AD. The sacrifices here had some interesting traits: the victims were killed by the sulphurous exhalations of a dark, foaming lake, identified by Virgil as the entrance to Hell, which was surrounded by a dense wood full of noxious vapors.

Accumulation and exchange of parasites during adaptive radiation in an ancient lake

In the ancient Lake Baikal, Russia, amphipod crustaceans have undergone a spectacular adaptive radiation, resulting in a diverse community of species. A survey of microsporidian parasites inhabiting endemic and non-endemic amphipod host species at the margins of Lake Baikal indicates that the endemic amphipods harbour many microsporidian parasite groups associated with amphipods elsewhere in Eurasia. While these parasites may have undergone a degree of adaptive radiation within the lake, there is little evidence of host specificity. Furthermore, a lack of reciprocal monophyly indicates that exchanges of microsporidia between Baikalian and non-Baikalian hosts have occurred frequently in the past and may be ongoing. Conversely, limitations to parasite exchange between Baikalian and non-Baikalian host populations at the margins of the lake are implied by differences in parasite prevalence and lack of shared microsporidian haplotypes between the two host communities. While amphipod hosts have speciated sympatrically within Lake Baikal, the parasites appear instead to have accumulated, moving into the lake from external amphipod populations on multiple occasions to exploit the large and diverse community of endemic amphipods in Lake Baikal.

Source-to-sink system in the south bank of Qinghai Lake

In the south bank of Qinghai Lake, numerous alluvial fans and coastal deposits have been formed. In terms of their developmental positions and relationships, the denudation system, depositional system, and transportation system consist of source-to-sink systems. Based on the field-investigation evidence and literature survey, it was confirmed that the developmental processes of these “source-to-sink” systems can be divided into three stages: the Early-Late Pleistocene stage, from 39 to 23 ka BP; Late Pleistocene-Early Holocene stage, from 39 to 10.7 ka BP; and modern stage. At the present time, these stages can still be identified as three levels of lake shore terraces. In the Late Pleistocene, the source-to-sink system indicates that the lake level was high, supply of clasts was sufficient, fan deltas had formed, and the lakeside plain continued to develop. At the end of the Late Pleistocene, with the sudden changes in global climate, the climate was dry and cold, and the lake level fell. At this time, the source-to-sink system showed that lake level was relatively low, supply of clasts was reduced, and transportation distance was longer; ancient sediments started to recycle in this system. Until modern times, alluvial fans in the south bank of Qinghai Lake have only rarely been developed, and the supply of clasts is primarily derived from the recirculation of paleo-shore sediments. Meanwhile, a large amount of sandy gravel beaches developed along the lake shore. By studying the multistage source-to-sink systems around modern lakes, the characteristics of the system in lake basins are enriched and provide an important analogy for researches of ancient lake basins.