Lake Salda Research Articles

Carbonic anhydrase activity and metabolite variation of different microalgae species at alkaline pHs

A significant increase in atmospheric greenhouse gases over the last century has led to the development of several methods and technologies to remove carbon dioxide (CO2). Microorganisms produce carbonate minerals through the natural mineralization of CO2; however, the feasibility of this process remains in research. This work aimed to study the cultivation of different microalgae under alkaline pH to maintain their potential for carbon mitigation. According to the results, the highest carbonic anhydrase activity has been reached (4.64 mg/g) for Chlamydomonas reinhardtii at a pH of 10. C. reinhardtii, at a pH of 9.5, yielded the highest chlorophyll content (23.58 mg/g), while Spirulina at a pH of 8.5 produced the highest biomass (882.9 mg/L). Also, a positive correlation existed between pH and lipid content for C. reinhardtii. Spirulina, however, exhibits the opposite effect. According to a principal component analysis, there is an opposite relationship between pH and carbonic anhydrase (CA) activity for C. reinhardtii and filamentous-type cyanobacteria from Salda Lake. The following order of the suitability of the microalgae species for high carbon capture is determined by the Analytic hierarchy process method: Spirulina>C. reinhardtii > Chlorella vulgaris > Coccus-type cyanobacteria > Filamentous-type cyanobacteria from Salda Lake. Additionally, this study provided important results regarding the cyanobacteria species isolated from an alkaline lake, Lake Salda. This would contribute to future studies of carbon capture and carbon mitigation mechanisms.

Morphological and Microbial Diversity of Hydromagnesite Microbialites in Lake Salda: A Mars Analog Alkaline Lake

ABSTRACTLake Salda, a terrestrial analog for the paleolake in Jezero Crater on Mars, hosts active, subfossil, and fossil hydromagnesite microbialites, making it an ideal location to study microbialite formation and subsequent processes. Our understanding of this record is still limited by an incomplete knowledge of the macro‐ and mesoscale morphotypes of microbialites, along with their spatial distribution and correlation with microbial and geochemical processes that influence microbialite formation. In this study, we investigated the spatial distribution, morphotypes, mineralogy, geochemistry, and microbial diversity of the microbialites and identified six distinct zones (Zone I to Zone VI) with major microbialite build‐ups in Lake Salda. Newly identified microbialites were classified based on the macro‐ and mesostructures. Our work shows that the lake contains stromatolites, thrombolites, stromatolitic thrombolites, dendrolites, and microbially induced sedimentary structures. At macroscale, Lake Salda microbialites exhibit hemispheres, stacked domes, and laterally linked columnar structures while minicolumns, knobs, mesoclots, laminae, and botryoidal structures are common at mesoscale. The macro‐ and mesoscale distribution of different microbialite types spatially correlates with microbial community composition and water depth. Deep‐growing microbialites with a low abundance of Cyanobacteria (∼1%–4%) and high abundance of Firmicutes (28%–93%) exhibit steeply convex lamination, producing finger‐like minicolumnar mesostructures. In contrast, shallow‐growing microbialites with a low abundance of Firmicutes (0%–5%) and high abundance of Cyanobacteria (11%–37%) have well‐preserved gently convex millimeter‐scale lamination, resulting in cauliflower mesostructures. Palygorskite ((Mg, Al)2Si4O10(OH)) is identified in the diatom‐rich microbial layer of the deep‐growing microbialites. Regardless of the microbialite types, hydromagnesite and aragonite are present in the extracellular polymeric substance (EPS)‐rich zone of the shallow and deep‐growing microbialites. Overall, environmental changes (e.g., water depth and, accommodation space) play a major role in the formation and spatial distribution of different microbialite morphologies at the macro‐ and mesoscale. Differences in the relative abundance of dominant microorganisms between mesostructured types suggest that mesomorphology may be influenced by changes in microbial diversity. Spatial variations in the microbialite morphotypes, along with the abundant presence of entombed biomass (e.g., mineralized filaments), may indicate areas that have a high potential for the preservation of biosignatures.

The study of mineral distribution using hyperspectral Hyperion data along the shores of Lake Salda/Türkiye

Lake Salda is considered the most similar region on Earth to search for evidence of life on Mars, and its shoreline is home to microbialites containing some of the oldest known fossilized records of life on our planet. Understanding the historical process of Mars is also crucial for predicting the future of our planet, given its transition from a watery world to an arid one. In mineralogical studies to be carried out in sensitive areas such as private protected areas, it is a priority not to damage the area, and mineralogical research using remote sensing methods is frequently used in such studies. In this study, the mineralogical characteristics of the geological formations in and around Kocaadalar Burnu peninsula, located in the southwest of Lake Salda, were examined using remote sensing techniques. Mineral studies of Lake Salda were conducted using data from the Hyperion data of the Earth Observation-1 (EO-1) satellite, which can detect in 220 bands between 357 and 2576 nm wavelengths which is capable of hyperspectral sensing. The EO-1 satellite, the first spacecraft of NASA’s New Millennium Programme, which operated successfully from its launch in 2000 until the end of its mission in 2017, carried the multispectral Advanced Land Imager and LEISA Atmospheric Corrector sensors, in addition to the Hyperion hyperspectral sensor. The Hyperspectral Material Identification tool in the Tactical Hyperspectral Operations Resource module of the ENVI software, the United States Geological Survey spectral library, and the Adaptive Coherence Estimator algorithm were used in the study. According to the results of this study conducted on the shores of Lake Salda, in addition to the hydromagnesite mineral, the existence of which was previously detected by various researchers, trona, vermiculite, rivadavite and borate minerals such as ulexite, tincalconite and colemanite were also detected. The results of this study have shown that remote sensing methods can make significant contributions to research in special protected areas such as Lake Salda. It is thought that the presence of trona and boron minerals in the region will contribute positively to the understanding of the historical process of Salda Lake.

Mid to late Holocene water level and inferred climate changes of Lake Salda (SW Anatolia/Turkey): evidence from high-resolution seismic and sediment-core records

Mid to late Holocene water level and inferred climate changes of Lake Salda (SW Anatolia/Turkey): evidence from high-resolution seismic and sediment-core records

Su Kalitesi Durum Değerlendirmesi- Salda Gölü, Türkiye

Inland water bodies, either flowing or non-flowing all around the world, are under the adverse effect of both the climate change and anthropogenic activities. The water surface areas of lakes and wetlands diminish over time and thus, this global reality brings together the deterioration of water quality especially if such water bodies confront with a variety of human activities exerting pollutants. An example of such a vulnerable ecosystem is the Lake Salda located in the southwestern part of Turkey. This lake has gained the attention of international public due to its similarities with Mars. Over a long period of time, many researches have been conducted in this lake by different disciplines and scientists to better understand its unique features. In this study, water samples from the three selected stations on the lake at three different depths were collected and analyzed on physico-chemical parameters, organic matter content, nutrients, metals and semi metals according to national legislation and Water Framework Directive (WFD) of EU. The results are tabulated and analyzed in detail considering the potential pollution sources arising from the lake’s basin. The pollutants are linked with the experimental measurements, and those parameters that exceeded the Environmental Quality Standards (EQS) are underlined. It is for sure that the lake necessitates utmost care and attention according to the results achieved.

Description of Gomphonella saldanensis sp. nov. (Bacillariophyceae) from hydromagnesite stromatolites in Salda Lake, Turkey

Lake Salda has a unique environment due to the presence of hydromagnesite stromatolites. Samples collected from the stromatolites contained a new diatom species, Gomphonella saldanensis sp. nov., which is described based on light and scanning electron microscopy. The main character of the taxon is its linear-lanceolate outline with a rostrate headpole and narrowly rounded footpole. The striae are strongly radiate mid-valve, becoming parallel to slightly radiate towards the poles. Elliptical Fourier and Linear Discriminant analyses indicate that there are different shape forms within the same taxon. Based on LM observations, G. saldanensis is similar to Gomphonema lagerheimii f. simplex, G. geisslerae, Gomphonella calcarea, G. olivacea, G. acsiae and G. coxiae. However, G. lagerheimii f. simplex differs with slightly radiate striae throughout the valve. Gomphonella geisslerae has a slightly undulate raphe and linear apices. Larger specimens of G. acsiae are lanceolate, clavate in smaller specimens. The remaining Gomphonella species, G. calcarea, G. coxiae and G. olivacea have broader outlines and lower stria densities.

Environmental and Mineralogical Controls on Biosignature Preservation in Magnesium Carbonate Systems Analogous to Jezero Crater, Mars.

Jezero Crater on Mars is a paleolacustrine environment where Mg-carbonates may host evidence of ancient life. To elucidate the environmental and mineralogical controls on biosignature preservation, we examined samples from five terrestrial analogs: Lake Salda (Turkey), Lake Alchichica (Mexico), Qinghai-Tibetan Plateau (China), Mg-carbonate playas (British Columbia, Canada), and a mine with fine-grained ultramafic tailings (Yukon, Canada). The mineralogical compositions of the samples varied, yet were often dominated by either aragonite (CaCO3) or hydromagnesite [Mg5(CO3)4(OH)2·4H2O]. Aragonite-rich samples from Alchichica, Mg-carbonate playas, and the ultramafic mine contained an abundance of entombed microbial biomass, including organic structures that resembled cells, whereas hydromagnesite-rich samples were devoid of microfossils. Aragonite often precipitates subaqueously where microbes thrive, thereby increasing the likelihood of biomass entombment, while hydrated Mg-carbonates typically form by evaporation in subaerial settings where biofilms are less prolific. Magnesite (MgCO3), the most stable Mg-carbonate, forms extremely slowly, which may limit the capture of biosignatures. Hydrated Mg-carbonates are prone to transformation via coupled dissolution-precipitation reactions that may expose biosignatures to degradation. Although less abundant, aragonite is commonly found in Mg-carbonate environments and is a better medium for biosignature preservation due to its fast precipitation rates and relative stability, as well as its tendency to form subaqueously and lithify. Consequently, we propose that aragonite be considered a valuable exploration target on Mars.

Trace and Rare Earth Element (REE) Geochemistry of Recently Formed Stromatolites at Lake Salda, SW Turkey

Stromatolites are the oldest recognized fossil recordings of life on Earth. Therefore, their study of them represents one of the most interesting topic that investigates the physio-chemical environmental conditions (formations and precipitations) at which the stromatolites formed. This work deals with the rare earth elements (REEs) geochemical characteristics and the redox-sensitive trace elements behavior of the stromatolites newly formed in Salda Lake, a closed system alkaline lake surrounded by serpentinite rocks in SW Turkey. The representative stromatolite samples collected from Salda Lake show higher contents of MgO (up to 41.5 wt.%), CO2+OH (up to 56.6 wt.%), and MgO/CaO ratio (up to 42.2 wt.%) referring to the stromatolites had been controlled by microorganisms and deposited in subtidal areas having hydro-magnesite and aragonite mineralogy. The average trace element contents of the stromatolites are 8.4 ppm V, 0.09 ppm Cr, 3.50 ppm Co, 95.6 ppm Ni, 0.73 ppm Cu, 1.55 ppm Rb, 37.6 ppm Sr, 0.59 ppm Y, 17.7 ppm Zr, 3.60 ppm Nb, 21 ppm Ba, 0.05 ppm Hf, 3.5 ppm As, 0.02 ppm Cd, 0.05 ppm U, 0.05 ppm Th, 2.85 ppm Pb, and 6.60 ppm Zn. The Post-Archean Australian Shale (PAAS)-normalized REE patterns of the stromatolites reveal that the heavy REEs (HREEs) are enriched relative to the light REEs (LREEs) with highly negative Y and Ce-anomalies and positive Eu-anomalies. This refers to the stromatolites formed in predominantly oxidizing environmental conditions at partially warm lake waters. In addition, the hydromagnesite composition of the Salda Lake stromatolites indicates that they were precipitated from the waters influenced by Mg-rich meteoric waters fed from the serpentinite rocks around the Lake.

FROM TOURISM GEOGRAPHY PERSPECTIVE SALDA LAKE (TURKEY) AND NEAR SURROUNDING

Salda Lake, located within the borders of Yeşilova district of Burdur province in the Antalya Section of the Mediterranean Region, is one of Turkey's most popular tourist attractions. Located in the southwest of Turkey and encompassing many lake basins, the “Lakes Region” has been designated as the “Lakes Region Ecotourism Development Region” in the Turkey 2023 tourism strategy and attention has been drawn to the tourism potential of the lakes in the region. Located in the Lakes Region, Lake Salda draws attention with its natural beaches and water sports opportunities, rich flora and fauna, recreation areas and camping areas by the lake, various accommodation opportunities and natural beauties, healing lake waters and rich tourism diversity. Rural tourism, lake tourism, ecological tourism, winter tourism, botanical tourism, health tourism and cultural tourism are the most developed types of tourism in and around Salda Lake. In this research, the geographical location, tourism potential and main tourism resources of both Yeşilova district and Salda Lake were examined. In addition, in this article focused on tourism geography, the negative ecological and socio-economic effects of increasing human pressure and tourism activities around Salda Lake were investigated. In this study, which deals with the examination of Salda Lake and its surroundings in terms of recreation and tourism activities, the natural and human environmental factors of the region are analyzed, and the main tourism advantages and disadvantages of the region are discussed. At the beginning of the most important results obtained from this research, it has been determined that factors such as climate change, uncontrolled and intense touristic flow, increasing environmental pollution and illegal construction threaten sustainable tourism in the Salda Lake basin.

Three new Achnanthidium (Bacillariophyceae) species from Lake Salda (Anatolia, Turkey), a deep soda lake

Background and aims – Kützing separated the genus Achnanthidium from the genus Achnanthes based on two species: Achnanthes minutissima and Achnanthidium microcephalum. These two genera were distinguished by the presence of stalks in the Achnanthes genus and their absence in Achnanthidium. Before electron microscopy, the difference between Achnanthes and Achnanthidium was not clear, especially in Achnanthidium minustissimum sensu lato. The aim of the study is to describe three new species of Achnanthidium from Lake Salda. Material and methods – Lake Salda is located in southwestern Anatolia, in Turkey. The diatoms were collected seasonally from four stations in the lake between 2016 and 2020, from different substrata (epipelic, epiphytic, and epilithic). Key results – Three new species belonging to the genus Achnanthidium have been found in Lake Salda, Turkey. Based on the morphological observations, all new taxa are part of the Achnanthidium minutissimum complex. Achnanthidium barlasii sp. nov. and A. dumlupinarii sp. nov. show a high degree of similarity to each other, but can be separated based on valve outline and a denser areolation, especially in striae close to the apices of the raphe valve. Both species can be distinguished from A. minutissimum based on more separate apices and less elliptic valves. In the case of A. dumlupinarii sp. nov., large specimens show slight undulations of the valve, which is a unique feature. Achnanthidium anatolicum sp. nov. is the most characteristic based on its valve width, broadly rounded valve apices, and almost straight valves in girdle view. All newly described Achnanthidium species can be found in lentic environments, with alkaline water and high calcium ion content. Conclusion – The newly described taxa occurred in the unique habitat of a soda lake. The environment of the lake is highly alkaline, rich in magnesium and calcium, and derived from limestone and dolomitic limestone rocks.

Deoxyribonucleic Acid Extraction from Mars Analog Soils and Their Characterization with Solid-State Nanopores.

Life detection on Mars is an important topic that includes a direct search for biomarkers. This requires instruments for in situ biomarker detection that are compact, lightweight, and able to withstand operations in space. Solid-state nanopores are excellent candidates that allow fast single-molecule detection. They can withstand high temperatures and be sterilized to minimize planetary contamination. The instruments are portable with low-power requirements. We demonstrate a few key results in advancing the use of nanopores for in-space applications. First, we developed modified deoxyribonucleic acid (DNA) extraction protocols to extract DNA from Mars analog soils. Second, we used silicon nitride nanopores to demonstrate the detection of extracted DNA and corresponding current characteristics. The yields and properties of extracted DNA (e.g., estimated diameters) varied somewhat by soil types, extraction methods, and nanopores used. The yields varied from a minimum of 0.9 ng DNA/g soil for a magnesium carbonate sample from Lake Salda to a maximum of 210 ng DNA/g soil for a calcium carbonate sample from Trona Pinnacles. For a given soil type, yields from different methods varied by a factor of up to 50. These observations motivate future studies with a broader range of Mars-like soils and improved instruments to increase signal-to-noise-ratio at higher measurement bandwidths.

Comparison of thresholding methods for shoreline extraction from Sentinel-2 and Landsat-8 imagery: Extreme Lake Salda, track of Mars on Earth

Lake Salda's extreme environment is geologically similar to Jezero Crater paleolake on Mars due to the formation of stromatolites and its extremely alkaline and cold water. It is critical to accurately determine the shoreline in the littoral zone where stromatolite formation occurs, in alkaline clean lakes like Salda, which contain traces of life on Mars, and in monitoring the change that occurs with climate and anthropogenic effect. The performance of global automatic thresholding algorithms on shoreline determination from NDWI and mNDWI water indices is compared in this study using Sentinel-2 and Landsat-8 images atmospherically corrected by different algorithms. Satellite images data acquired on August 12, 2020 for Sentinel-2 and August 11, 2020 for Landsat-8 on Lake Salda were used to determining the shoreline. The shoreline data measured in situ concurrently with the Sentinel-2 satellite acquisition was used as reference data. In the accuracy analysis, ground control points created inside and outside the lake at a distance of 1 pixel and 0.5 pixel to the reference shoreline for each satellite image were used. The performance of the optimal threshold values determined by each thresholding algorithm in the water index images was assessed using Kappa coefficient, Overall Accuracy (OA), %OA of Inside (%OAinside) and %OA of Outside (%OAoutside) statistics metrics. The optimal threshold values vary depending on the image and the atmospheric correction algorithm applied to the image. The NDWI index produces more accurate results in both Sentinel-2 and Landsat-8 satellite images. While atmospheric correction algorithms do not affect the results in Landsat-8 images, the Sen2Cor algorithm outperforms iCOR in Sentinel-2 images. For thresholding algorithms to be used in different water index and satellite images, Intermode, Isodata, IJ_Isodata, Minimum and Otsu algorithms in Landsat-8_LaSRC_NDWI and Landsat-8_iCOR_NDWI images, and Intermode, Minimum and Huang algorithms in Sentinel-2_Sen2Cor_NDWI images produce the best results. Because the Minimum algorithm causes significant gaps in the lake surface, the Huang and Intermode algorithms should be used for Sentinel-2_Sen2Cor_NDWI images. The 0 (zero) threshold value in the water indices images has a high accuracy only in the NDWI water indices generated from the Landsat-8 image.

‘What if this is my last chance?’: Developing a last-chance tourism motivation model

Visiting disappearing attractions before they are gone has recently become a motivation for some tourists. From this viewpoint, the purpose of this study is to identify the precursory role of environmental consciousness in the determination of motivations concerning local attractions within the scope of last-chance tourism and the impacts of such elements of motivation on place satisfaction and recommendation. To this end, the study was conducted with 352 domestic tourists visiting Lake Salda, and the research model was tested based on Partial Least Square Structural Equation Modelling. The results indicate that environmental consciousness has a positive impact on all elements of motivation. Natural reflection, last-chance experience as well as fascination also have a positive impact on place satisfaction. Likewise, joining the story of the destination, fascination and place satisfaction are shown to have a positive impact on recommendation. The findings are further examined in detail using the importance-performance map analysis method. • Environmental consciousness affects motivations including last chance experience. • Last chance experience has a positive impact on place satisfaction. • Some motivations and place satisfaction have a positive impact on recommendation. • Last chance experience comes third among the reasons for visiting Lake Salda.

Assessment of Shoreline Changes using Historical Satellite Images and Geospatial Analysis along the Lake Salda in Turkey

This study was performed along the shorelines of Lake Salda in Turkey during the elapsed period from 1975 to 2019 in order to detect shoreline changes. Within this framework, geographic information system, digital shoreline analysis system, Modified Normalized Difference Water Index, and multi-temporal satellite images were utilized. The measurement of shoreline displacement was mainly divided into six analysis regions. In digital shoreline analysis system, several statistical parameters such as end point rate, linear regression rate, shoreline change envelope, and net shoreline movement were computed to measure the rates of shoreline displacement in terms of erosion and accretion. The maximum shoreline change between 1975 and 2019 was determined as 556.45 m by shoreline change envelope parameter. The maximum shoreline change was 16.35 m/year by end point rate parameter and 12.91 m/year by linear regression rate parameter. While erosion has been observed in 3rd, 4th and 6th segments, accretion has been observed in other segments. When all the transects were taken into consideration, an accretion observed. The results indicate that there is a decrease in area of the lake. Experiment results show that integrated use of multi-temporal satellite images and statistical parameters are very effective and useful for shoreline change analysis. It is thought that the structures such as irrigation pond and dam that are built on the streams that recharge the lake and average rainfall and average temperature conditions are the main reasons of the fluctuations and changes in the shorelines.

A Survey on Global Thresholding Methods for Mapping Open Water Body Using Sentinel-2 Satellite Imagery and Normalized Difference Water Index

The aim of this study is to investigate the performance of fifteen automatic thresholding methods, namely Huang and Wang’s fuzzy thresholding method, inter-mode thresholding method, isodata thresholding method, Li and Tam’s thresholding method, maximum entropy thresholding method, mean thresholding method, minimum error thresholding method, minimum thresholding method, moment-preserving thresholding method, Otsu’s thresholding method, percentile (p-tile) thresholding method, Renyi’s entropy thresholding method, Shanbhag’s thresholding method, triangle thresholding method and Yen’s thresholding method, for mapping open water body using Sentinel-2 data based on Normalized Difference Water Index (NDWI). Sentinel-2 data was acquired on 22 September 2018 and Lake Salda from Turkey was selected as a test site. Due to the lack of digital reference data of the test site, Support Vector Machine (SVM) classification was implemented to Sentinel-2 data and the classified image was utilized as reference data since previous studies proved that SVM classification provided better results than the thresholding methods. SVM classification results were evaluated using 1000 random points and the Overall Accuracy (OA) and Kappa coefficient were obtained 96.2% and 0.90, respectively. The thresholding methods were assessed using the statistical measures, namely OA, Kappa and Misclassification Error (ME). Considering the remote sensing perspective, all thresholding methods presented satisfying results having at least 92% OA for open water body extraction. The obtained accuracy results showed that minimum thresholding method was the best method among these fifteen algorithms with 0.000264 ME, 99.9355% OA and 0.9987 Kappa. On the other hand, p-tile and Shanbhag’s thresholding method provided the worst accuracy results for open water body delineation.

Biotic and Abiotic Imprints on Mg-Rich Stromatolites: Lessons from Lake Salda, SW Turkey

Modern hydrated Mg rich stromatolites are actively growing along the shallow shorelines of Lake Salda (SW Turkey). An integrated approach involving isotopic, mineralogical, microscopic, and organic/geochemical techniques along with culture-independent molecular methods were applied to various lake samples to assess the role of microbial processes on stromatolite formation. This study further explores the biosignature preservation potential of fossil stromatolites by comparing with textures, lipid profiles and isotopic composition of the modern stromatolites. Similar lipid profile and δ13C isotope values in active and fossil stromatolites argue that CO2 cycling delicately balanced between photosynthetic and heterotrophic (aerobic) activity as in the active ones may have regulated stromatolite formation in the lake. A decrease in the exopolymeric substances (EPS) profile of the mat and concurrent hydromagnesite precipitation imply a critical role for EPS in the formation of stromatolite. Consistently, a discrete, discontinuous lamination and clotted micropeloidal textures with cyanobacterial remnants in the fossil stromatolites likely refer to partial degradation of EPS, creating local nucleation sites and allowing precipitation of hydrated Mg minerals and provide a link to the active microbial mat in the modern stromatolites. Our results for the first time provide strong evidence for close coupling of cyanobacterial photosynthesis and aerobic heterotrophic respiration on hydromagnesite textures involved in the stromatolite formation of Lake Salda. The creation of photosynthesis induced high-pH conditions combined with a change in the amount and properties of the EPS and the repetition of these processes over time seems to be a possible pathway for stromatolite growth in the lake. Understanding these microbial symbioses and their mineralized records may provide new insights on the formation mechanism of Mg-rich carbonates not only for terrestrial geological records but also for planetary bodies like Mars, where hydrated Mg-carbonate deposits have been identified in possible paleolake deposits at Jezero crater, the landing site of the NASA Mars 2020 rover.

Determination of Climatic Conditions Changes Impacts on Lake Salda Basin

Determination of Climatic Conditions Changes Impacts on Lake Salda Basin

Simultaneous reproduction of two killifish congeners in the highly alkaline Lake Salda (Turkey)

The reproductive ecology of Western Palaearctic killifishes is poorly documented and was addressed in this study by investigating, for the first time, two closely related endemic killifish species, namely Aphanius fontinalis and Aphanius saldae. Fish samples were collected monthly from January to October 2017 to test whether the killifishes reproduce simultaneously in the highly alkaline Lake Salda (Turkey). Variation in the mean gonadosomatic index and the frequency of hydrated oocytes indicated that the two species reproduce synchronously from April to September. The timing of reproduction was affected more by day length than by water temperature. Larvae of a parasitic nematode (Eustrongylides sp.) were also observed in the gonadal tissue of some individuals. The effects of parasite infection on basic reproductive parameters were tested in A. fontinalis. Parasite infection had no significant effect on gonad weight, but was associated with significantly decreased fecundity and oocyte diameter. In both species, fecundity was related to fish size; however, the regression model showed non-significant results for the parasite-infected A. fontinalis subsamples. Further research is needed to address the ecological and evolutionary consequences of the coexistence of A. fontinalis and A. saldae and the overlap in breeding seasons.

Evidence of Possible Recharge Zones for Lake Salda (Turkey)

This study explores the evidence of recharge locations using hydrogeochemical and physicochemical measurements in an alkaline lake, Lake Salda, in Burdur, Turkey. In-situ measurements have been performed using a conductivity–temperature–depth device to map the physicochemical dynamic of the lake. Water and sediment samples were collected on the surface and floor of the lake. A seismic study was also carried out in order to observe the geometry of the lake floor. In addition, thermal distribution was mapped using the thermal band of Landsat 7 ETM+ and Landsat 8 satellite images. Temperature and specific conductance measurements were mapped using a new technique, Empirical Bayesian Kriging (EBK), from the lake’s surface to the floor. According to interpolation maps obtained from the EBK, possible water inputs were observed close to a fault at the south-eastern part of the lake. The results of thermal band imaging also reveal the probability of a fault effecting the recharge on the surface. The results of water and sediment samples present a richness in Mg2+ and Fe2+ elements respectively on the floor of the lake. Finally, seismic results show some possible recharge zones on the floor of the lake, and sediment results indicate that there should be peridotite occurrence below the alluvium unit.

Solar forcing and climate variability during the past millennium as recorded in a high altitude lake: Lake Salda (SW Anatolia)

Climate variability is a well-known phenomenon and has been frequently, though complex, linked to solar forcing on different time scales. The importance of solar forcing related climate variability is crucial in our understanding of paleoclimate and future climate changes, as well as building climate models. Here in, we present the late Holocene (last ca 1400) climate records from Lake Salda in SW Anatolia using high-resolution micro X-ray Fluorescence (μ-XRF), magnetic susceptibility (MS), stable isotopes (δ13C and δ18O) and TOC-TIC measurements. The age model is constructed by using radionuclide (210Pb, 137Cs and 14C) dating methods. The lake's high-resolution multiproxy results revealed lake water level fluctuations associated with humid and dry spells during the last 1400 years. Periods of higher lake levels are consistent with solar maxima in total solar irradiance and vice versa. Moreover, the Lake Salda records clearly show dry Dark Ages Cold Period (DACP), humid Medieval Climatic Anomaly (MCA), dry Little Ice Age (LIA), and humid Modern Warm Period (MoWP). These records suggest that the solar forcing, through its influence on the atmospheric circulation, is the main mechanism of climate change during the DACP, MCA, LIA and MoWP in this region.