Scientific drilling projects in ancient lakes: integrating geological and biological histories

Sedimentary sequences in ancient or long-lived lakes can reach several thousands of meters in thickness and often provide an unrivalled perspective of the lake's regional climatic, environmental, and biological history. Over the last few years, deep drilling projects in ancient lakes became increasingly multi- and interdisciplinary, as, among others, seismological, sedimentological, biogeochemical, climatic, environmental, paleontological, and evolutionary information can be obtained from sediment cores. However, these multi- and interdisciplinary projects pose several challenges. The scientists involved typically approach problems from different scientific perspectives and backgrounds, and setting up the program requires clear communication and the alignment of interests. One of the most challenging tasks, besides the actual drilling operation, is to link diverse datasets with varying resolution, data quality, and age uncertainties to answer interdisciplinary questions synthetically and coherently. These problems are especially relevant when secondary data, i.e., datasets obtained independently of the drilling operation, are incorporated in analyses. Nonetheless, the inclusion of secondary information, such as isotopic data from fossils found in outcrops or genetic data from extant species, may help to achieve synthetic answers. Recent technological and methodological advances in paleolimnology are likely to increase the possibilities of integrating secondary information, e.g., through molecular dating of molecular phylogenies. Some of the new approaches have started to revolutionize scientific drilling in ancient lakes, but at the same time, they also add a new layer of complexity to the generation and analysis of sediment core data. The enhanced opportunities presented by new scientific approaches to study the paleolimnological history of these lakes, therefore, come at the expense of higher logistic, communication, and analytical efforts. Here we review types of data that can be obtained in ancient lake drilling projects and the analytical approaches that can be applied to empirically and statistically link diverse datasets for creating an integrative perspective on geological and biological data. In doing so, we highlight strengths and potential weaknesses of new methods and analyses, and provide recommendations for future interdisciplinary deep drilling projects

Thalassiobeckiaceae – a new family of the class Centrophyceae (Bacillariophyta)

A new freshwater genus Thalassiobeckia studied in light (LM) and scanning electron microscope (SEM) from the Pliocene sediments of Lake Baikal has been considered in the composition of the new monotype family Thalassiobeckiaceae in the class Centrophyceae (Bacillariophyta). Both new taxa are diagnosed by a combination of following morphological features: a) the presence of loculate areolae with internal cribra and external foramina; b) the arrangement of areolae on the valve face in radiating non-fasciculated striae; c) the presence of the marginal ring of tubular processes on the valve mantle; d) the availability of several rimoportulae on the valve face/mantle junction and e) the availability of one-several valve face fultoportula.Новый пресноводный род Thalassiobeckia, изученный в световом (СМ) и сканирующем электронном микроскопе (СЭМ) из плиоценовых отложений озера Байкал, рассматривается в составе нового монотипного семейства Thalassiobeckiaceae в классе Centrophyceae (Васillariophyta). Оба новых таксона характеризуются сочетанием следующих морфологических признаков: а) присутствием локулярных ареол с внутренним крибрумом и наружным фораменом; b) расположением ареол и лицевой поверхности створки в радиальных рядах, не образующих пучки; c) присутствием краевого кольца трубковидных выростов на загибе створки; d) наличием нескольких двугубых выростов на границе лицевой части створки и загиба и (е) одного-нескольких выростов с опорами на лицевой части створки

Comparison of diatom successions from Mazovian (Poland) and Alexandrian (Belarus) lacustrine interglacial deposits

Comparative analysis of two profiles (Gvoznitsa, Malorita district, southwestern Belarus and Krępiec, Lublin Upland, eastern Poland) of Alexandrian and/or Mazovian (=Likhvinian, Holsteinian) age shows different diatom successions which are correlated with pollen data. Various species of Cyclotella, Stephanodiscus and Aulacoseira predominate at Gvoznitsa, while the diatom flora at Krępiec is more diverse and includes also Synedra, Asterionella, and Fragilaria taxa. Certain apparently extinct taxa of Cyclotella (C. comta var. lichvinensis (Jousé) Loginova, C. comta var. pliocaenica Krasske, C. temperiana (Loginova) Loginova, C. michiganiana var. parvula Loginova (C. parvula Loginova), are typical of the Mazovian and/or Alexandrian Interglacial