Long-chain alkenones in saline meromictic lakes of the North Minusinsk depression (southern Siberia): first information and a possible connection with water level dynamics
D. Yu. Rogozin1,2, A. O. Bulkhin1,2, V. V. Zykov1, E. A. Ivanova2, A. V. Darin3, I. A. Kalugin3, O. A. Baturina4, M. R. Kabilov4
1Institute of Biophysics of SB RAS, Krasnoyarsk, Russia
2Siberian Federal University, Krasnoyarsk, Russia
3Sobolev Institute of Geology and Mineralogy of SB RAS, Novosibirsk, Russia
4Institute of Chemical Biology and Fundamental Medicine of SB RAS, Novosibirsk, Russia
Keywords: long chain alkenones, haptophyte algae, meromictic lakes, water level, climate, paleo-limnological reconstruction, 18S rDNA
Abstract
Long chain alkenones are temperature-sensitive and in some cases salinity-sensitive lipids with great potential for reconstruction of past climate because they are well preserved in sediments for a long time. These lipids are produced only by some species of Haptophyta algae. The chain length and degree of unsaturation of alkenones vary depending on environmental conditions such as temperature and salinity. We examined for the first time the sediments of saline meromictic lakes Shira and Uchum located in arid steppes of North-Minusinsk Depression (southern Siberia) for long-chain alkenones. We found the uneven vertical distributions of C37-C40 alkenones with different unsaturation indices on the sediments of both lakes. In hypolimnion of Lake Uchum the highly abundant population of the haptophytes of the order Isochrysidales was detected both by 18SrDNA deep sequencing and microscopy. The haptophyte species and composition of alkenones were similar to saline stratified lakes of northern Great Plains of North America (Sasketchewan, Canada) with similar climate and dissolved ion composition of the lakes water. The relative abundance of the C37:4 alkenone in the sediments of lakes Shira and Uchum have been changing in accordance with the water-level and salinity changes documented for the recent ca. 100 years. Therefore, we have shown that long-chain alkenones can be used as a proxy of the climate-driven water-level changes in the saline lakes of southern Siberia.
|
