Late Pleistocene-Holocene and Recent Ostracoda of the Laptev Sea and their importance for paleoenvironmental reconstructions

Abstract

-This work is the first detailed description of the Late Pleistocene-Holocene and Recent Ostracoda of the Laptev Sea. A total of 45 species in 22 genera and 13 families have been identified. All these species are described monographically. Three different ecological assemblages of ostracodes corresponding to different combinations of environmental parameters have been established; they are restricted to three regions of the sea: western-central, eastern, and southern. The recent ostracode assemblages of the Laptev Sea have been compared with those from other Arctic areas and are most similar to those of the Beaufort and Kara seas. Data on recent Ostracoda are used for paleoenvironmental reconstructions on the eastern shelf and western continental slope of the Laptev Sea. For this purpose, ostracodes from five sections obtained from these parts of the sea have been examined. The oldest sediments, which are of Late Pleistocene age (15.8 cal. ka BP), have been recovered in a core from the western continental slope. These yielded five ostracode assemblages, which correspond to different paleoenvironments and replaced each other in the course of the rapid postglacial sea-level rise, thus showing variations in the Atlantic water inflow from the west and freshwater discharge from the subaerially exposed shelf. On the outer shelf of the eastern part of the sea, the rapid sea-level rise in the Early Holocene (lowermost dating 11.3 cal. ka BP) led to a rapid transition from assemblages of brackish-water nearshore environments to those of modernlike normal marine environments; modern environments were established about 8.2 cal. ka ago. Since the core sections from the inner shelf correspond to the time when the level of the sea had already reached its modern values, the changes in the taxonomic composition of ostracode assemblages primarily mirror variations in river runoff. STEPANOVA Holocene the sedimentation rates remained quite stable, varying from 1.2 mm/yr in the Lena River valley to 0.1 mm/yr in the Khatanga River valley (Bauch et al., 2001b). DOI:In marine sediments, the changes caused by sealevel rise and variations in river discharge and water parameters are reflected in downcore variations of fossil benthic assemblages, such as ostracodes, mollusks, and foraminifers; among these, ostracodes are the most sensitive to environmental changes, water depth and salinity. Analysis of ostracode assemblages allows reconstructing paleoenvironments in great detail. Since this group is so important for paleoreconstructions, we have undertaken a comprehensive study of recent and fossil ostracodes from the Laptev Sea, data on which still remain quite scarce. This work is based on new materials obtained in the framework of the cooperative RussianGerman projects "Laptev Sea System" and "Laptev Sea System-2000." CHAPTER 1. MATERIALS AND METHODS In this study we investigated samples obtained by Taldenkova and, partly, by the author from sediment core sections PS51/138-12(10), PS51/135-4, PS51/080-13(11), and PS51/92-12(11...

Deep-sea Benthic Ostracodes from Multiple Core and Epibenthic Sledge Samples in Icelandic Waters

“…6.5-6) Note: Comprehensive synonymy and detailed discussion are found in Swanson and Ayress (1999) and Stepanova (2006) and Yasuhara et al (2009c).…”

Deglacial sea level history of the East Siberian Sea and Chukchi Sea margins

“…6). In the Laptev and Kara seas, Rabilimis is found in modern samples of similar depths (Stepanova, 2006). These nearshore ostracode species are either absent or occur in low numbers at deeper sites in the Laptev and Kara seas.…”

“…The primary sources of ostracode taxonomy and ecology were Stepanova (2006), Yasuhara et al (2014), and Gemery et al (2015) and the references therein. The study by Gemery et al (2015) gives the modern depth range and ecological data for 1340 modern surface samples from the Arctic and subarctic seas.…”

Central Arctic Ocean paleoceanography from ∼ 50 ka to present, on the basis of ostracode faunal assemblages from the SWERUS 2014 expedition

“…The modern circum-Arctic distribution of R. mirabilis is confined to shallow (< 200 m) water depths (Fig. 6a, b, and c; Hazel, 1970;Neale and Howe, 1975;Taldenkova et al, 2005;Stepanova, 2006;Gemery et al, 2015) and Table 5 lists historical occurrences. R. mirabilis can also tolerate a range of salinities, explaining its presence in regions near river mouths with reduced salinity (Fig.…”

“…gov/paleo-search/). The primary sources of taxonomy and ecology were papers by Cronin et al (1994Cronin et al ( , 1995Cronin et al ( , 2010, Gemery et al (2015), Joy and Clark (1977), Stepanova (2006), Stepanova et al (2003Stepanova et al ( , 2007Stepanova et al ( , 2010, Whatley et al (1996Whatley et al ( , 1998, and Yasuhara et al (2014).…”