Hydrological Changes of the Amazon During the Last Glacial-Interglacial Cycle in Central Amazonia (Brazil)

1995 ◽  
Vol 82 (5) ◽  
pp. 232-235 ◽  
Author(s):  
J. M�ller ◽  
G. Irion ◽  
J. Nunes de Mello ◽  
W. Junk
Keyword(s):  
Last Glacial ◽  
Hydrological Changes ◽  
Central Amazonia ◽  
The Last Glacial

Hydrological changes of the amazon during the last glacial-interglacial cycle in Central Amazonia (Brazil)

1995 ◽  
Vol 82 (5) ◽  
pp. 232-235 ◽  
Author(s):  
J. M�ller ◽  
G. Irion ◽  
J. Nunes de Mello ◽  
W. Junk
Keyword(s):  
Last Glacial ◽  
Hydrological Changes ◽  
Central Amazonia ◽  
The Last Glacial

scholarly journals Ostracods as ecological and isotopic indicators of lake water salinity changes: the Lake Van example

2019 ◽  
Vol 16 (10) ◽  
pp. 2095-2114 ◽  
Author(s):  
Jeremy McCormack ◽  
Finn Viehberg ◽  
Derya Akdemir ◽  
Adrian Immenhauser ◽  
Ola Kwiecien
Keyword(s):  
Lake Water ◽  
Lake Level ◽  
Water Salinity ◽  
Glacial Period ◽  
Lake Van ◽  
Faunal Assemblage ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Hydrological Changes ◽  
The Last Glacial

Abstract. Ostracods are common lacustrine calcitic microfossils. Their faunal assemblage and morphological characteristics are important ecological proxies, and their valves are archives of geochemical information related to palaeoclimatic and palaeohydrological changes. In an attempt to assess ostracod ecology (taxonomic diversity and valve morphology) combined with valve geochemistry (δ18O and δ13C) as palaeosalinity indicators, we analysed sedimentary material from the International Continental Scientific Drilling Program (ICDP) Ahlat Ridge site from a terminal and alkaline lake, Lake Van (Turkey), covering the last 150 kyr. Despite a low species diversity, the ostracod faunal assemblage reacted sensitively to changes in the concentration of total dissolved salts in their aquatic environment. Limnocythere inopinata is present throughout the studied interval, while Limnocythere sp. A is restricted to the Last Glacial period and related to increased lake water salinity and alkalinity. The presence of species belonging to the genus Candona is limited to periods of lower salinity. Valves of Limnocytherinae species (incl. L. inopinata) display nodes (hollow protrusions) during intervals of increased salinity. Both the number of noded valves and the number of nodes per valve appear to increase with rising salinity, suggesting that node formation is related to hydrological changes (salinity and/or alkalinity). In contrast to Lake Van's bulk δ18O record, the δ18O values of ostracod valves do record relative changes of the lake volume, with lower values during high lake level periods. The δ13C values of different species reflect ostracod habitat preferences (i.e. infaunal vs. epifaunal) but are less sensitive to hydrological changes. However, combined with other proxies, decreasing Holocene δ13C values may indicate a freshening of the lake water compared to the low lake level during the Last Glacial period. The Lake Van example underscores the significance and value of coupling ostracod ecology and valve geochemistry in palaeoenvironmental studies of endorheic lake basins.

scholarly journals Ostracods as ecological and isotopic indicators of lake water salinity changes: The Lake Van example

2019 ◽  
Author(s):  
Jeremy McCormack ◽  
Finn Viehberg ◽  
Derya Akdemir ◽  
Adrian Immenhauser ◽  
Ola Kwiecien
Keyword(s):  
Lake Water ◽  
Lake Level ◽  
Water Salinity ◽  
Glacial Period ◽  
Lake Van ◽  
Faunal Assemblage ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Hydrological Changes ◽  
The Last Glacial

Abstract. Ostracods are common lacustrine calcitic microfossils. Their faunal assemblage and morphological characteristics are important ecological proxies, while their valves are archives of geochemical information related to palaeoclimatic and palaeohydrological changes. In an attempt to assess ostracod ecology (taxonomic diversity and valve morphology) combined with valve geochemistry (δ18O and δ13C) as palaeosalinity indicators, we analysed material from terminal and alkaline Lake Van (Turkey) covering the last 150 kyr. Despite a low species diversity, the ostracod faunal assemblage reacted sensitive to changes in the concentration of total dissolved salts in their aquatic environment. Limnocythere inopinata is present throughout the studied interval, while Limnocythere sp. A is restricted to the Last Glacial period and related to increased lake water salinity and alkalinity. The presence of species belonging to the genus Candona is limited to periods of lower salinity. Valves of limnocytherinae species (incl. L. inopinata) display nodes (hollow protrusions) during intervals of increased salinity. Both the amount of noded valves and the number of nodes per valve appear to increase with rising salinity, suggesting that node formation is related to hydrological changes (salinity and/or alkalinity). In contrast to Lake Van's inorganic δ18O record, the δ18O values of ostracod valves do record relative changes of the lake volume, with lower values during high lake level periods. The δ13C values of different species reflect ostracod habitat preferences (i.e., infaunal versus epifaunal) but are less sensitive to hydrological changes. However, combined with other proxies, decreasing Holocene δ13C values may indicate a freshening of the lake water compared to the low lake level during the Last Glacial period. The Lake Van example underscores the significance and value of coupling ostracod ecology and valve geochemistry in palaeoenvironmental studies of endorheic lakes basins.

The movement of pre-adapted cool taxa in north-central Amazonia during the last glacial

2017 ◽  
Vol 169 ◽  
pp. 1-12 ◽  
Author(s):  
Carlos D'Apolito ◽  
Maria Lúcia Absy ◽  
Edgardo M. Latrubesse
Keyword(s):  
North Central ◽  
Last Glacial ◽  
Central Amazonia ◽  
The Last Glacial

Hydrological changes in eastern europe during the last 40,000 yr inferred from biomarkers in Black Sea Sediments

2013 ◽  
Vol 80 (3) ◽  
pp. 502-509 ◽  
Author(s):  
Frauke Rostek ◽  
Edouard Bard
Keyword(s):  
Black Sea ◽  
Ice Cores ◽  
Russian Plain ◽  
The Black Sea ◽  
Permafrost Degradation ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Hydrological Changes ◽  
The Last Glacial

The Black Sea is connected to a large drainage area including the European Russian Plain, part of the Alps and southeastern Europe. To study the hydrological changes in this basin over the last 40,000 years, we measured specific terrigenous biomarkers for wetland vegetation in well-dated sediments from the northwestern Black Sea, spanning the last glacial period (lacustrine phase) and the Holocene (marine phase). Low abundances of these biomarkers are observed during the North Atlantic ice melting and cooling events known as Heinrich Events 4 to 2, the Last Glacial Maximum and the Younger Dryas Event. Increased biomarker inputs characterize the mild climate phases known as Dansgaard–Oeschger Interstadials, the Bølling/Allerød and Preboreal Warmings indicating increased erosion due to permafrost degradation, higher primary productivity and/or wetland extension in the drainage basin. The final retreat of the Fennoscandian Ice Sheet from the Russian Plain occurs during the early part of Heinrich Event 1 and is characterized by increased biomarker concentrations in a typical series of four deglacial clay layers. For the last glacial period, the correspondence in timing between the biomarker records and the atmospheric CH4 record from ice cores, suggests an important CH4 contribution due to boreal permafrost thawing and wetland emission.

Reconstructions of the past distribution of Testudo graeca mitochondrial lineages in the Middle East and Transcaucasia support multiple refugia since the Last Glacial Maximum

2021 ◽  
pp. 10-17
Author(s):  
Oguz Turkozan
Keyword(s):  
Middle East ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Testudo Graeca ◽  
Last Glacial ◽  
The Past ◽  
Precipitation Seasonality ◽  
Multiple Refugia ◽  
The Last Glacial Maximum ◽  
The Last Glacial

A cycle of glacial and interglacial periods in the Quaternary caused species’ ranges to expand and contract in response to climatic and environmental changes. During interglacial periods, many species expanded their distribution ranges from refugia into higher elevations and latitudes. In the present work, we projected the responses of the five lineages of Testudo graeca in the Middle East and Transcaucasia as the climate shifted from the Last Glacial Maximum (LGM, Mid – Holocene), to the present. Under the past LGM and Mid-Holocene bioclimatic conditions, models predicted relatively more suitable habitats for some of the lineages. The most significant bioclimatic variables in predicting the present and past potential distribution of clades are the precipitation of the warmest quarter for T. g. armeniaca (95.8 %), precipitation seasonality for T. g. buxtoni (85.0 %), minimum temperature of the coldest month for T. g. ibera (75.4 %), precipitation of the coldest quarter for T. g. terrestris (34.1 %), and the mean temperature of the driest quarter for T. g. zarudyni (88.8 %). Since the LGM, we hypothesise that the ranges of lineages have either expanded (T. g. ibera), contracted (T. g. zarudnyi) or remained stable (T. g. terrestris), and for other two taxa (T. g. armeniaca and T. g. buxtoni) the pattern remains unclear. Our analysis predicts multiple refugia for Testudo during the LGM and supports previous hypotheses about high lineage richness in Anatolia resulting from secondary contact.

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