Evolution of the plankton paleome in the Black Sea from the Deglacial to Anthropocene

Abstract

The complex interplay of climate shifts over Eurasia and global sea level changes modulates freshwater and saltwater inputs to the Black Sea. The dynamics of the hydrologic changes from the Late Glacial into the Holocene remain a matter of debate, and information on how these changes affected the ecology of the Black Sea is sparse. Here we used Roche 454 next-generation pyrosequencing of sedimentary 18S rRNA genes to reconstruct the plankton community structure in the Black Sea over the last ca. 11,400 y. We found that 150 of 2,710 species showed a statistically significant response to four environmental stages. Freshwater chlorophytes were the best indicator species for lacustrine conditions (>9.0 ka B.P.), although the copresence of previously unidentified marine taxa indicated that the Black Sea might have been influenced to some extent by the Marmara Sea since at least 9.6 ka calendar (cal) B.P. Dinoflagellates, cercozoa, eustigmatophytes, and haptophytes responded most dramatically to the gradual increase in salinity after the latest marine reconnection and during the warm and moist midHolocene climatic optimum. According to paired analysis of deuterium/hydrogen (D/H) isotope ratios in fossil alkenones, salinity increased rapidly with the onset of the dry Subboreal after ∼5.2 ka B.P., leading to an increase in marine fungi and the first occurrence of marine copepods. A gradual succession of dinoflagellates, diatoms, and chrysophytes occurred during the refreshening after ∼2.5 ka cal B.P. with the onset of the cool and wet Subatlantic climate and recent anthropogenic perturbations.amplicon pyrosequencing | ancient plankton DNA | D/H ratios in alkenones | paleoenvironment

Volume 364: Chicxulub: Drilling the K-Pg Impact Crater

“…The diversity of microbial life will be quantified and compared with geological and geochemical data to answer questions such as was the microbiology shaped by the post-impact hydrothermal system, and did organic matter get trapped within hydrothermal minerals? The deep biosphere will be investigated using culturing, molecular biological analyses of DNA, searching for biosignatures such as hopanoids and other lipids/biomolecules, and paired analyses of paleome (the genome of an extinct species) and lipid biomarkers (Cockell et al, 2005;Coolen and Overmann, 2007;Coolen et al, 2013). Iron isotopes will also be used to detect biosignatures because they are particularly useful for studies of ancient, severely metamorphosed and/or altered rocks (Yamaguchi et al, 2005).…”

“…Study of biomarkers at the molecular level (high-pressure liquid chromatography [HPLC] and liquid chromatography-mass spectrometry [LC-MS]) and pigments (chlorophylls, bacteriochlorophylls, and their degradation products) from photosynthetic organisms (algae and photosynthetic bacteria) may indicate changes in and evolution of photosynthetic organism populations after impact. It is expected that both marine and terrestrial organic matter have accumulated in the post-impact sedimentary rock and that the paired stratigraphic analysis of the paleome and lipid biomarkers and their isotopic compositions using precisely dated core material will provide detailed insights into post-impact environmental conditions and the recovery and evolution of surface and deep subsurface life (Coolen et al, 2007(Coolen et al, , 2013. Of interest is the ocean chemistry and temperature immediately following the impact and any indicators of climatic recovery.…”

Planktonic foraminifera-derived environmental DNA extracted from abyssal sediments preserves patterns of plankton macroecology

“…In marine sediments, the presence of eDNA sequences has been reported from organic-rich layers in the Mediterranean dating back to 217 ka (Coolen and Overmann, 2007) and 125 ka (Boere et al, 2011), in sediments covering the last 11.4 kyr in the Black Sea (Coolen et al, 2013), and in up to 32.5 kyr old deposits in the Atlantic (Lejzerowicz et al, 2013;Pawłowska et al, 2014). Recently, Kirkpatrick et al (2016) showed that the abundance of planktonic DNA was decreasing within 100-200 ka in sediments of the Bering Sea but traces were still detected in sediments up to 1.4 Ma.…”

The effects of growth phase and salinity on the hydrogen isotopic composition of alkenones produced by coastal haptophyte algae

“…These two effects act in concert so that alkenone δD becomes less negative as salinity increases. As such, the δD of alkenones recovered from sediment cores has been used to estimate changes in past surface salinity, for example, in the Eastern Mediterranean (van der Meer et al, 2007), the Black Sea (van der Meer et al, 2008;Coolen et al, 2013) and the Agulhas region (Kasper et al, 2014).The reason for this correlation between salinity and fractionation is presently not clear. One hypothesis for the increase in fractionation factor observed with increasing salinity is that at higher salinities water transport across cell membranes is reduced as the cell maintains osmotic potential and that this reduced transport decreases the effective size of the pool of internal cell water from which hydrogen can be fixed (Sachse and Sachs, 2008).…”