Microbial diversity in the deep subsurface of Lake Ohrid
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Abstract. To date, little is known about the role of spring waters with respect to authigenic carbonate precipitation in a shallow lacustrine setting. Lake Ohrid, located in Southeastern Europe, is a large lake fed to over 50% by karstic springs of which half enter subaquatically and influence significantly its ecology and species distribution. In order to evaluate how sedimentological processes are influenced by such shallow-water springs, the Kališta subaquatic spring area in the north west of Lake Ohrid was investigated by a sidescan sonar survey and with sediment traps and three transects of gravity short cores. Results indicate that sedimentation in the spring area is dominated by authigenic carbonate precipitation. High sedimentation rates and evidences for bio-induced precipitation processes were observed in the water column and in the sediments. Two distinct stratigraphic units characterize the shallow subsurface, both composed of carbonate silts with high carbonate contents of up to 96%, but differing in color, carbonate content and diatom content. A chronological correlation of the cores by radiocarbon dates and 137Cs activities places the transition between the two stratigraphic units after ~1955 AD. At that time, coastal sedimentation changed drastically to significantly darker sediments with higher contents of organic matter and more abundant diatoms. This change coincides with the recent human impact of littoral eutrophication.
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Lake Prespa, Lake Ohrid and Lake Skadar are the biggest lakes in the Balkan Peninsula. By reason of continuous existence and relatively stable ecological conditions millions years those lakes have a unique collection of flora and fauna.In this paper is presented biodiversity of macrophyte vegetation from Lake Prespa, Lake Ohrid and Lake Skadar. In those three lakes macrophyte vegetation is distributed in zones (belts). The biodiversity of macrophytes is different in those lakes and it is in direct dependence of different altitudes, lakes surfaces and lakes depths.
Peninsula
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Abstract. Ancient Lake Ohrid is a steep-sided, oligotrophic, karst lake that was tectonically formed most likely within the Pliocene and often referred to as a hotspot of endemic biodiversity. This study aims on tracing significant lake level fluctuations at Lake Ohrid using high-resolution acoustic data in combination with lithological, geochemical, and chronological information from two sediment cores recovered from sub-aquatic terrace levels at ca. 32 and 60 m water depth. According to our data, significant lake level fluctuations with prominent lowstands of ca. 60 and 35 m below the present water level occurred during Marine Isotope Stage (MIS) 6 and MIS 5, respectively. The effect of these lowstands on biodiversity in most coastal parts of the lake is negligible, due to only small changes in lake surface area, coastline, and habitat. In contrast, biodiversity in shallower areas was more severely affected due to disconnection of today sub-lacustrine springs from the main water body. Multichannel seismic data from deeper parts of the lake clearly image several clinoform structures stacked on top of each other. These stacked clinoforms indicate significantly lower lake levels prior to MIS 6 and a stepwise rise of water level with intermittent stillstands since its existence as water-filled body, which might have caused enhanced expansion of endemic species within Lake Ohrid.
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Qinghai Lake is located in the northeastern edge of the Tibetan-Qinghai Plateau. It is the largest saline lake in China. Due to uneven uplift of the plateau, some of the basins formed lakes in an isolated drainage system. The geochemistry of bedrocks affects the hydrological chemistry of drainage area and the physicochemical features of the Qinghai Lake. The main source of organic carbon is the ecological system surrounding the lake; Weathering of rocks also contributes to the carbon source in the lake. The chemistry of the Lake is heterogeneous in both vertical and horizontal dimensions; Changing of seasons also influences the hydrochemistry. These characteristics bring forth a unique microbiological ecology as well as a coupled carbon and metal cycling system. Enhanced concentrations of Fe, SO 2-_4, CO_3 2-, Ca, Mg ions provide sufficient nutrients for the prosperity of a complex ecological system. This biological cycling consequently provides sufficient chemicals for biomineralization. As has been surveyed, the lake is of high diversity of algae, whose populations and community structures change seasonally. As a part of the evolution of the lake, the biological relics have been recorded as organic or inorganic biosignatures in the bottom sediments. Further study of the biological records and their relationship to the evolution of the local microbial ecology and cycling of carbon and other elements is expected to have important implications for climatic and environmental changes in the Tibetan-Qinghai Plateau.
Limnology
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Ohrid Lake is one of the oldest lakes in the world, formed about 2-3 million years ago.Many of lakes of the globe are about 10,000 to 45,000 thousand years old and formed during the glacial period.In an old lake, with hills and mountains that separated them from other waters, a whole collection of plants and animals is developed.Lake Ohrid is located at a height of 695m, with a surface of 358.2 km 2 and a coastline of 87.5 km.About 2/3 of the lake is in the North Macedonian part and 1/3 belongs to the Albanian side.It represents an exceptional source of water, the great biological diversity and the endemic species that are presently threatened by many factors.Most of the Ohrid Lake basin is formed by tectonic forces.At a later stage of the alpine oogenesis the holes of Ohrid, Prespa and Debarca are formed.The Ohrid Lake itself is formed on Bilisht-Korça-Debarca.As a geomorphologic characteristic of the catchment basin we mention abrasive formations (rugged rocks, bare rocks and rocks and subsoil), river formations (river valleys, river beds, erosive and accumulative terraces) karstic formations (cracks, water holes, pits and fields karstic surface as well as holes and underground holes).Biomonitoring is the use of biological indicators as assessors of environmental change.Since, chemical compounds of the rivers pass through mass flows over a short period of time, chemical monitoring gives an instantaneous water quality picture only for the sampling moment.In Albania, biological monitoring based in diatoms, for the first time is carried out in Albanian rivers (fresh water), the data are presented by Miho et al., (2005); on PhD thesis by Kupe L., (2006).After then had continued with further studies in the area of ecological (diatoms) assessment of fresh and marshes water.
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Lacustrine sediments are widely used to investigate the impact of climatic change on biogeochemical cycling. In these sediments, subsurface microbial communities are major actors of this cycling but can also affect the sedimentary record and overprint the original paleoenvironmental signal. We therefore investigated the subsurface microbial communities of the oldest lake in Europe, Lake Ohrid (North Macedonia, Albania), to assess the potential connection between microbial diversity and past environmental change using 16S rRNA gene sequences. Along the upper ca. 200 m of the DEEP site sediment record spanning ca. 515 thousand years (ka), our results show that Atribacteria, Bathyarchaeia and Gammaproteobacteria structured the community independently from each other. Except for the latter, these taxa are common in deep lacustrine and marine sediments due to their metabolic versatility adapted to low energy environments. Gammaproteobacteria were often co-occurring with cyanobacterial sequences or soil-related OTUs suggesting preservation of ancient DNA from the water column or catchment back to at least 340 ka, particularly in dry glacial intervals. We found significant environmental parameters influencing the overall microbial community distribution, but no strong relationship with given phylotypes and paleoclimatic signals or sediment age. Our results support a weak recording of early diagenetic processes and their actors by bulk prokaryotic sedimentary DNA in Lake Ohrid, replaced by specialized low-energy clades of the deep biosphere and a marked imprint of erosional processes on the subsurface DNA pool of Lake Ohrid.
Stromatolite
Environmental change
Biogeochemical Cycle
Microbial mat
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Ohrid Lake is a tectonic lake and he has many endemic species covering the whole food-chain, from phytoplankton to fish.The biological investigation was based on a microscopic examination of diatom communities, which are the mostly common used as bio indicators of aquatic system health.The diatom community are collected on August 2011, like epiphyte in different macrophytes and in different depth from shoreline in estuaries of Vërdova river (T6: 5m, 6.5m, 9m, 11m, 12m, 13m, 14m, 19m).In this paper in total we will present 8 samples, in which sample we have determined many diatoms species and ecological status in each sample.Several studies have clearly demonstrated that diatom community's change with increasing concentrations of both organic and inorganic load of substances, making them the preferred organism group for in situ biomonitoring methods.This study clearly showed that it was the shift in dominance of certain species, as shown by relative abundances and they reflected in water ecology in Lake Ohrid.A pennate diatom was classified as the most dominant species in eight samples; we have identified many endemic species.The trophic classes oscillated from 2.1 (meso-eutroph) to 2.6 (eutroph) and saprobic classes oscillated from 1.4 (oligosaprob) to 1.6 (Oligosaprob deri β-mesosaprob).Implementation of Waste Water Treatment Plant in Pogradeci town, will improve the ecological status in the Lake.
Dominance (genetics)
Bioindicator
Epiphyte
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Recently, the discovery of active microbial life in deep-sea sediments has triggered a rapid development of the field known as the "deep biosphere." Geomicrobiological investigations in lacustrine basins have also shown a substantial microbial impact on lake sediments similar to that described for the marine record. Although only 30 % of the lake sites drilled by the International Continental Drilling Program (ICDP) have included microbial investigations, these lakes cover a relatively wide range of salinities (from 0.15 to 33.8 %), pH (from 6.0 to 9.8) and environmental conditions (from very arid to humid subtropical conditions). Here, we analyze results of very recent ICDP lake sites including subsurface biosphere research from southern Patagonia (Laguna Potrok Aike) to the Levantine area (Dead Sea) as well as the East Anatolian high plateau (Lake Van) and Macedonia (Lake Ohrid). These various settings allow the examination of the impact of contrasting environments on microbial activity and their subsequent role during early diagenesis. Furthermore, they permit the identification of biosignatures of former microbial activity recorded in the sediments as well as investigating the impact of microbes in biogeochemical cycles. One of the general outcomes of these preliminary investigations is data to support the hypothesis that microbes react to climatically driven environmental changes that have a direct impact on their subsurface distribution and diversity. This is clear at conspicuous levels associated with well-known climatic periods such as the Medieval Climatic Anomaly or the Little Ice Age. Although more research is needed, this relationship between prevailing microbial assemblages and different climatic settings appears to dominate the lacustrine sites studied until to date.
Biogeochemical Cycle
Scientific drilling
Geologic record
Stromatolite
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