Adaptation of the Arctic limnosystems to the climate change

Under current rapid climate change in the Arctic, especially lakes have important parameters for the ecosystems safety. Hydrological regime of a lacustrine catchment mostly is a result of talik - lake body thermic and water interaction. Flat big lake can form a new hydrographical system consisting of small lakes chain. The level of initial lake surface can be declined by thermokarst cracks; but during long time water income will be saved due to thawing permafrost and ground water inflow. Talik stores a sufficient water temperature of deep lake layers for ecosystems. So, in lakes of the Lena River delta the water temperature under 2 meters of ice thickness was 0,1-2°C and reached 23°C in summer, although hydrochemical parameters changed in a big value especially in winter. DOC, that is significant for the limnosystems, values from 4.6 to 33.7 mg/l under ice and 3.5-6.6 - in summer. αCDOM(440) in April 2018 differs in the rate of 0.91-11.16 nm^-1 in winter and 0.42-5.12 - in summer. Electrical conductivity of water had value from 23 to 120 μS/cm - in summer and 140-277 - in winter.

Radio dating of the top layer of lacustrine sediments gives age 2810±240 cal. kyr BP on the 35 cm of core of thermokarst lake in the Lena River Delta; the deposition rate is 0.13 mm per year. The Yamal lake had quick deposition rate of sediments: the age 145.64 ± 9.98 years (²¹⁰Pb) was on the 14 cm of a core; a deposition rate - 0.89 ± 0.06 mm/year. Talik depth is about 25 m under Yakutian lake and 10 m - under Yamal lake. Therefore, in consideration of the dating and deposition rate results talik can be recognized as one of the main factors of a high resilience of Arctic lakes and is a buffer of an ecosystem: it saves a lake thermic regime, biogeochemical elements exchange as well as water income.

The projects have been supported by RFBR 18-05-60291 and 19-05-00683, Resource educational center "Chemistry" and Scientific program 1 of SPBU. DOC, CDOM, nutrience analyses were done in OSL AARI.