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The Sea of Marmara is the connection between the vast Black Sea-Caspian Sea basin (Pontocaspian) and the Global Ocean via the Mediterranean Sea. Its water levels and water conditions has widely varied over times. Combining two cores in the Sea of Marmara (Turkey) and using organic-walled dinoflagellate cyst assemblages as the main proxy (combined with alkenones, diatoms and benthic foraminifera), allow qualitatively reconstructing water conditions during Marine Isotopic Stage (MIS) 6 and 5, such as salinity and oxygen level. A clear main marine phase is illustrated in MIS 5e. A minor marine incursion occurred during MIS 5c, mostly supported by alkenone data. The rest of the record indicates brackish Pontocaspian conditions, with more Spiniferites inaequalis in MIS 6 and more S. cruciformis in the non-marine parts of MIS 5. At the MIS 6/MIS 5 transition, an earlier initial marine flooding in the Sea of Marmara (dinocyst assemblages) in comparison to the Black Sea was highlighted. The marine reconnection occurred at different moments as seen in the terrestrial vegetation reconstructed from pollen analysis linking the two seas. The sapropels of the Sea of Marmara form when marine water penetrates at depth from the Aegean Sea beneath a layer of lower salinity water. Variations of the residence time of the marine deep water in a stratified Sea of Marmara are potentially an important factor underlying hypoxia/anoxia and sapropel deposition. When combining surface water proxies with benthic foraminifera (test assemblages and presence of inner organic lining), it appears that the successive MIS 5 sapropels formed under decreasing salinity and oxygen availability conditions as the marine inflow was increasingly restricted. Understanding the hydrologic evolution of the Sea of Marmara during MIS 5 implies taking into account that the Bosphorus and Dardanelle straits are hydrodynamically coupled and may not be simplified as on/off switches based on present day sill depths. • Dinocyst analyses of last interglacial and previous glacial in the Sea of Marmara on two long cores. • Marine phase in MIS5e (dinocysts, benthic foraminifera, alkenones) minor in MIS5c • BrackishPontocaspian conditions for rest of sequence although different in MIS6 & 5. • Earlier marine flooding at beginning of MIS5e in Sea of Marmara than in Black Sea. • Three sapropels highlight decreasing anoxic conditions over time. [ABSTRACT FROM AUTHOR]

The Caspian Sea, the largest land–locked water body worldwide, has undergone water level changes much larger than that of the oceans and within decades only. In this paper, we review the Caspian Sea level observations since the beginning of instrumental measurements (AD 1880). We summarize and discuss different aspects of the Caspian Sea levels including a) history of sea level observations with a critical appraisal of their modes of measurements and data accuracy, b) long-term, seasonal and short-term sea level changes, c) forecast of sea level, and d) impact of sea level changes. The Caspian seasonal and short-term water level changes (sub-annual) occur due to river flooding, meteorological forcing, steric changes, tsunami and tidal effects, which range from a few centimetres in a half day (i.e. the tide) up to 4 m in 5–7 days during severe storm surges. Long-term water level changes (i.e. multiyear to multidecadal) are mainly attributed to water budget; two prominent elements of which are riverine influx and evaporation from the water surface. From the mid-twentieth century, water withdrawal for human activities is also incorporated in the Caspian Sea water budget. The long-term mean water level change ranged over 3 m during instrumental observations. It rose at a rate of 15 cm y−1 during the period of 1978–1995 and dropped at a rate of 8 cm y−1 since 1996. During sea level rise, coastal inundation happened leading to huge economic loss; however, it improved some coastal wetland ecosystem services. Current sea level fall causes wetland reduction and desiccation. The sea level falls of the 1960s and 1970s enhanced vertical mixing; however, during both last rise and fall of the water level, the Caspian marine environment had limited vertical circulation, leading to oxygen deficiency in deep areas. Adding to anthropogenic influence, global warming through changes in precipitation, evaporation and wind regime will have significant impact on the Caspian Sea level already at the end of the current century. Despite of the importance of the local, regional and global impacts of Caspian Sea level changes, forecasts still have great uncertainty and were not successful yet. [ABSTRACT FROM AUTHOR]

Abstract: Palynological analyses (pollen and dinocysts) of a sediment core taken in the Kara-Bogaz Gol have been used to reconstruct rapid and catastrophic environmental changes over the last two centuries (chronology based on 210Pb). A natural cyclicity (65 years) of water level changes in the Caspian Sea (CS) and in the Kara-Bogaz Gol (KBG) and anthropogenic factors (building of a dam separating the CS and the KBG waters) combine to induce rapid changes in water levels of the KBG, in the salinity of its waters and in vegetation cover of its surroundings. The impact of low water levels on the dinocysts is marked by a lower diversity and the survival of two species that are typical of the KBG, the Caspian Sea species present in the KBG having disappeared. During periods of higher water levels (AD 1871–1878), the lake is surrounded by a steppe-like vegetation dominated by Artemisia; whereas during periods of low water levels (AD 1878–1913 and AD 1955–1998), the emerged shore are colonised by Chenopodiaceae. The period of AD 1913–1955 corresponding to decreasing water levels has an extremely low pollen concentration and a maximum of reworking of arboreal taxa. During the last low-level period, humans responded by abandoning the shores of the bay. What happened to the KBG can be used as an example of what may happen in the future for the Aral Sea. A problem of reworking of Tertiary dinocysts into modern deposits has been detected owing to the knowledge of the modern dinoflagellate assemblages recently made available through a water survey. A comparison to modern surface pollen samples from Central Asia (Anzali, Caspian Sea south and central basins, Aral Sea, Lake Balkhash, Lake Issyk-Kul and the Chinese Tien-Shan range) allows us to establish the potential reworking of at least five arboreal pollen taxa possibly by run-off and dust storms. [Copyright &y& Elsevier]

During most of the Holocene, the Faiyum Depression in Middle Egypt was connected to the Nile River and contained an extensive freshwater lake. Geochemical analysis of a lacustrine sediment core (Qaru-9) from the depression provides evidence of changes in Nile sediment discharge related to changes in Ethiopian African Monsoon (EAM) precipitation, and allows us to reconstruct changes in Nile River runoff, vegetation and erosion in both the near and far catchment. Major and trace elements reveal significant changes in clastic sediment provenance, with sources oscillating between (i) a Blue/Atbara Nile fluvial contribution during the African Humid Period (AHP) and in the late Holocene (i.e. c. 10–7.5 & c.4–0 ka cal BP, respectively), (ii) a White Nile contribution between c. 7.5–4 ka cal BP with aeolian contributions and carbonate deposits occurring during local arid and wetter conditions, respectively. We also use geochemical data to assign variations in the paleowater properties of the Faiyum Lake (i.e. redox condition, paleosalinity and paleoproductivity) throughout the Holocene. Changes in pollen and algal remains in early to mid Holocene sediments confirm a deep freshwater lake prior to c. 10–8 ka cal BP but diminishing water levels after this period. The Faiyum Lake was a deep freshwater lake between 10 & 6 ka cal BP with fluctuating lake levels between 6–4 ka cal BP and during the late Holocene. In the later period, an abrupt drop in lake level occurred followed by increasing salinity as hydrological modifications occurred. • Blue Nile influxes silt to Faiyum during AHP and late Holocene. • White Nile influxes c. 7.5–4 ka cal BP. • A deep freshwater lake existed c. 10–8 ka and became shallow after this period. • Pollens confirm a deep freshwater lake early-mid Holocene and drop later. • In late Holocene, salinity increased in the lake as hydrological modifications. [ABSTRACT FROM AUTHOR]