THE FIRST DATED PREGLACIAL DIATOM RECORD IN LAKE LADOGA, NW RUSSIA

65-6

Sedimentological processes and environmental variability at Lake Ohrid (Macedonia, Albania) between 640 ka and present day

Lake Ohrid (FYROM, Albania) is thought to be more than 1.2 million years old and hosts more than 200 endemic species. As a target of the International Continental Scientific Drilling Program (ICDP), a successful deep drilling campaign was carried out within the scope of the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) project in 2013. Here, we present lithological, sedimentological, and (bio-)geochemical data from the upper 247.8 m of the overall 569 m long DEEP site sediment succession from the central part of the lake. According to an age model, which is based on nine tephra layers (1st order tie points), and on tuning of biogeochemical proxy data to orbital parameters (2nd order tie points) and to the global benthic isotope stack LR04 (3rd order tie points), respectively, the analyzed sediment sequence covers the last 640 ka

Spatial competition in a global disturbance minimum; the seabed under an Antarctic ice shelf

The marine habitat beneath Antarctica's ice shelves spans ∼1.6 million km2, and life in this vast and extreme environment is among Earth's least accessible, least disturbed and least known, yet likely to be impacted by climate-forced warming and environmental change. Although competition among biota is a fundamental structuring force of ecological communities, hence ecosystem functions and services, nothing was known of competition for resources under ice shelves, until this study. Boreholes drilled through a ∼ 200 m thick ice shelf enabled collections of novel sub-ice-shelf seabed sediment which contained fragments of biogenic substrata rich in encrusting (lithophilic) macrobenthos, principally bryozoans – a globally-ubiquitous phylum sensitive to environmental change. Analysis of sub-glacial biogenic substrata, by stereo microscopy, provided first evidence of spatial contest competition, enabling generation of a new range of competition measures for the sub-ice-shelf benthic space. Measures were compared with those of global open-water datasets traversing polar, temperate and tropical latitudes (and encompassing both hemispheres). Spatial competition in sub-ice-shelf samples was found to be higher in intensity and severity than all other global means. The likelihood of sub-ice-shelf competition being intraspecific was three times lower than for open-sea polar continental shelf areas, and competition complexity, in terms of the number of different types of competitor pairings, was two-fold higher. As posited for an enduring disturbance minimum, a specific bryozoan clade was especially competitively dominant in sub-ice-shelf samples compared with both contemporary and fossil assemblage records. Overall, spatial competition under an Antarctic ice shelf, as characterised by bryozoan interactions, was strikingly different from that of open-sea polar continental shelf sites, and more closely resembled tropical and temperate latitudes. This study represents the first analysis of sub-ice-shelf macrobenthic spatial competition and provides a new ecological baseline for exploring, monitoring and comparing ecosystem response to environmental change in a warming world

PALEOLIMNOLOGICAL TRANSECT (PLOT) PROJECT: THE PREGLACIAL TO POSTGLACIAL HISTORY OF THE RUSSIAN ARCTIC BASED ON THE PRELIMINARY POLLEN RESULTS

14-1

THE PROJECT PLOT (PALEOLIMNOLOGICAL TRANSECT) - OVERVIEW AND PRELIMINARY RESULTS ON THE PREGLACIAL TO POSTGLACIAL HISTORY OF THE RUSSIAN ARCTIC

70-7

The Hominin Sites and Paleolakes Drilling Project:Inferring the environmental context of human evolution from eastern African rift lake deposits

Funding for the HSPDP has been provided by ICDP, NSF (grants EAR-1123942, BCS-1241859, and EAR-1338553), NERC (grant NE/K014560/1), DFG priority program SPP 1006, DFG-CRC-806 “Our way to Europe”, the University of Cologne (Germany), the Hong Kong Research Grants Council (grant no. HKBU201912), the Peter Buck Fund for Human Origins Research (Smithsonian), the William H. Donner Foundation, the Ruth and Vernon Taylor Foundation, Whitney and Betty MacMillan, and the Smithsonian’s Human Origins Program.The role that climate and environmental history may have played in influencing human evolution has been the focus of considerable interest and controversy among paleoanthropologists for decades. Prior attempts to understand the environmental history side of this equation have centered around the study of outcrop sediments and fossils adjacent to where fossil hominins (ancestors or close relatives of modern humans) are found, or from the study of deep sea drill cores. However, outcrop sediments are often highly weathered and thus are unsuitable for some types of paleoclimatic records, and deep sea core records come from long distances away from the actual fossil and stone tool remains. The Hominin Sites and Paleolakes Drilling Project (HSPDP) was developed to address these issues. The project has focused its efforts on the eastern African Rift Valley, where much of the evidence for early hominins has been recovered. We have collected about 2 km of sediment drill core from six basins in Kenya and Ethiopia, in lake deposits immediately adjacent to important fossil hominin and archaeological sites. Collectively these cores cover in time many of the key transitions and critical intervals in human evolutionary history over the last 4 Ma, such as the earliest stone tools, the origin of our own genus Homo, and the earliest anatomically modern Homo sapiens. Here we document the initial field, physical property, and core description results of the 2012–2014 HSPDP coring campaign.Publisher PDFPeer reviewe

The first dated preglacial diatom record in Lake Ladoga: long-term marine influence or redeposition story?

Preglacial environments in Lake Ladoga, the largest European lake, located within the limits of the Scandinavian glaciations, are very poorly investigated compared to postglacial ones. They were primarily reconstructed based on the studies of terrestrial boreholes and outcrops, often incomplete and poorly dated. Previous diatom studies established that during the Eemian marine transgression, the Ladoga basin became a part of the marine Baltic-White Sea connection. However, the environments established in Lake Ladoga after the regression of the Eemian Sea are not known. This article discusses the first Early Weichselian (MIS5, ~ 118–80 ka) diatom record in Lake Ladoga obtained within the frame of the Russian-German research project PLOT. Low concentrations and selective preservation of diatoms in the preglacial sediments point to unstable high-energy environments. The presence of marine diatoms is thought to result from reworking of marine Eemian sediments, rather than direct marine influence. We argue that post-Eemian environments in Lake Ladoga were neither marine nor glaciolacustrine, as previously suggested. The Early Weichselian diatom record formed in a shallow-water part of a lake affected by inflowing streams transporting large amounts of eroded material. No analogues of the preglacial environments can be found in the postglacial Lake Ladoga. Our record demonstrates close similarity to other Early Weichselian diatom records in the Ladoga region suggesting their formation under the same conditions. Similar trends in concentrations of diatoms, diatom fragments and other siliceous microfossils reflect changing sediment supply, hydrodynamics or reworking intensity. Their lower values ~ 118–113 and ~ 90–80 ka could reflect the Early Weichselian cooling stages, while their increase between ~ 113 and 90 ka might indicate enhanced erosion intensity and increased sediment supply corresponding to the climate amelioration

THE FIRST DATED PREGLACIAL DIATOM RECORD IN LAKE LADOGA, NW RUSSIA

65-6