TY - JOUR A1 - Nazarova, Larisa B. A1 - Bleibtreu, Annette A1 - Hoff, Ulrike A1 - Dirksen, Veronika A1 - Diekmann, Bernhard T1 - Changes in temperature and water depth of a small mountain lake during the past 3000 years in Central Kamchatka reflected by a chironomid record JF - Quaternary international : the journal of the International Union for Quaternary Research N2 - We investigated chironomid assemblages of a well-dated sediment core from a small seepage lake situated at the eastern slope of the Central Kamchatka Mountain Chain, Far East Russia. The chironomid fauna of the investigated Sigrid Lake is dominated by littoral taxa that are sensitive to fluctuations of the water level. Two groups of taxa interchangeably dominate the record responding to the changes in the lake environment during the past 2800 years. The first group of littoral phytophilic taxa includes Psectrocladius sordidellus-type, Corynoneura arctica-type and Dicrotendipes nervosus-type. The abundances of the taxa from this group have the strongest influence on the variations of PCA 1, and these taxa mostly correspond to low water levels, moderate temperatures and slightly acidified conditions. The second group of taxa includes Microtendipes pedellus-type, Tanytarsus lugens-type, and Tanytarsus pallidicornistype. The variations in the abundances of these taxa, and especially of M. pedellus-type, are in accordance with PCA 2 and correspond to the higher water level in the lake, more oligotrophic and neutral pH conditions. Water depths (WD) were reconstructed, using a modern chironomid-based temperature and water depth calibration data set (training set) and inference model from East Siberia (Nazarova et al., 2011). Mean July air temperatures (T July) were inferred using a chironomid-based temperature inference model based on a modern calibration data set for the Far East (Nazarova et al., 2015). The application of transfer functions resulted in reconstructed T July fluctuations of approximately 3 degrees C over the last 2800 years. Low temperatures (11.0-12.0 degrees C) were reconstructed for the periods between ca 1700 and 1500 cal yr BP (corresponding to the Kofun cold stage) and between ca 1200 and 150 cal yr BP (partly corresponding to the Little Ice Age [LIA]). Warm periods (modern T July or higher) were reconstructed for the periods between ca 2700 and 1800 cal yr BP, 1500 and 1300 cal yr BP and after 150 cal yr BP. WD reconstruction revealed that the lake level was lower than its present level at the beginning of the record between ca 2600 and 2300 cal yr BP and ca 550 cal yr BP. Between ca 2300 and 700 cal yr BP as well as between 450 and 150 cal yr BP, the lake level was higher than it is today, most probably reflecting more humid conditions. (C) 2016 Elsevier Ltd and INQUA. All rights reserved. KW - Kamchatka KW - Chironomids KW - Palaeoclimate KW - Late Holocene KW - Temperature KW - Water depth Y1 - 2017 U6 - https://doi.org/10.1016/j.quaint.2016.10.008 SN - 1040-6182 SN - 1873-4553 VL - 447 SP - 46 EP - 58 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Nazarova, Larisa B. A1 - Grebennikova, Tatiana A. A1 - Razjigaeva, Nadezhda G. A1 - Ganzey, Larisa A. A1 - Belyanina, Nina I. A1 - Arslanov, Khikmat A. A1 - Kaistrenko, Victor M. A1 - Gorbunov, Aleksey O. A1 - Kharlamov, Andrey A. A1 - Rudaya, Natalia A1 - Palagushkina, Olga A1 - Biskaborn, Boris K. A1 - Diekmann, Bernhard T1 - Reconstruction of Holocene environmental changes in Southern Kurils (North-Western Pacific) based on palaeolake sediment proxies from Shikotan Island JF - Global and planetary change N2 - We investigated a well-dated sediment section of a palaeolake situated in the coastal zone of Shikotan Island (Lesser Kurils) for organic sediment-geochemistry and biotic components (diatoms, chironomids, pollen) in order to provide a reconstruction of the palaeoenvironmental changes and palaeo-events (tsunamis, sea-level fluctuations and landslides) in Holocene. During the ca 8000 years of sedimentation the changes in organic sediment-geochemistry and in composition of the diatoms and chironomids as well as the shifts in composition of terrestrial vegetation suggest that the period until ca 5800 cal yr BP was characterized by a warm and humid climate (corresponds to middle Holocene optimum) with climate cooling thereafter. A warm period reconstructed from ca 900 to at least ca 580 cal yr BP corresponds to a transition to a Nara-Heian-Kamakura warm stage and can be correlated to a Medieval Warm Period. After 580 cal yr PB, the lake gradually dried out and climatic signals could not be obtained from the declining lacustrine biological communities, but the increasing role of spruce and disappearance of the oak from the vegetation give evidences of the climate cooling that can be correlated with the LIA. The marine regression stages at the investigated site are identified for ca 6200-5900 (at the end of the middle Holocene transgression), ca 5500-5100 (Middle Jomon regression or Kemigawa regression), and ca 1070-360 cal yr BP (at the end of Heian transgression). The lithological structure of sediments and the diatom compositions give evidences for the multiple tsunami events of different strengths in the Island. Most remarkable of them can be dated at around ca 7000, 6460, 5750, 4800, 950 cal yr BP. The new results help to understand the Holocene environmental history of the Southern Kurils as a part of the Kuril-Kamchatka and Aleutian Marginal Sea-Island Arc Systems in the North-Western Pacific region. KW - Kurils KW - North-Western Pacific KW - Palaeoclimate KW - Sea level KW - Diatoms KW - Chironomids KW - Pollen Y1 - 2017 U6 - https://doi.org/10.1016/j.gloplacha.2017.10.005 SN - 0921-8181 SN - 1872-6364 VL - 159 SP - 25 EP - 36 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Nazarova, Larisa B. A1 - de Hoog, Verena A1 - Hoff, Ulrike A1 - Dirksen, Oleg A1 - Diekmann, Bernhard T1 - Late Holocene climate and environmental changes in Kamchatka inferred from the subfossil chironomid record JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - This study presents a reconstruction of the Late Holocene climate in Kamchatka based on chironomid remains from a 332 cm long composite sediment core recovered from Dvuyurtochnoe Lake (Two-Yurts Lake, TYL) in central Kamchatka. The oldest recovered sediments date to about 4500 cal years BP. Chironomid head capsules from TYL reflect a rich and diverse fauna. An unknown morphotype of Tanytarsini, Tanytarsus type klein, was found in the lake sediments. Our analysis reveals four chironomid assemblage zones reflecting four different climatic periods in the Late Holocene. Between 4500 and 4000 cal years BP, the chironomid composition indicates a high lake level, well-oxygenated lake water conditions and close to modern temperatures (similar to 13 degrees C). From 4000 to 1000 cal years BP, two consecutive warm intervals were recorded, with the highest reconstructed temperature reaching 16.8 degrees C between 3700 and 2800 cal years BP. Cooling trend, started around 1100 cal years BP led to low temperatures during the last stage of the Holocene. Comparison with other regional studies has shown that termination of cooling at the beginning of late Holocene is relatively synchronous in central Kamchatka, South Kurile, Bering and Japanese Islands and take place around 3700 cal years BP. From ca 3700 cal years BP to the last millennium, a newly strengthened climate continentality accompanied by general warming trend with minor cool excursions led to apparent spatial heterogeneity of climatic patterns in the region. Some timing differences in climatic changes reconstructed from chironomid record of TYL sediments and late Holocene events reconstructed from other sites and other proxies might be linked to differences in local forcing mechanisms or caused by the different degree of dating precision, the different temporal resolution, and the different sensitive responses of climate proxies to the climate variations. Further high-resolution stratigraphic studies in this region are needed to understand the spatially complex pattern of climate change in Holocene in Kamchatka and the surrounding region. KW - Kamchatka KW - Holocene KW - Chironomids KW - Palaeoclimate KW - Temperature Y1 - 2013 U6 - https://doi.org/10.1016/j.quascirev.2013.01.018 SN - 0277-3791 VL - 67 IS - 9 SP - 81 EP - 92 PB - Elsevier CY - Oxford ER -