Delft University of Technology Mollusc biodiversity in late Holocene nearshore environments of the Caspian Sea A baseline for the current biodiversity crisis van de Velde, Sabrina; Wesselingh, Frank P.; Yanina, Tamara A.; Anistratenko, Vitaliy V.; Neubauer, Thomas A.; ter Poorten, Jan Johan; Vonhof, Hubert B.; Kroonenberg, Salomon B. DOI 10.1016/j.palaeo.2019.109364 Publication date 2019 Document Version Final published version Published in Palaeogeography, Palaeoclimatology, Palaeoecology Citation (APA) van de Velde, S., Wesselingh, F. P., Yanina, T. A., Anistratenko, V. V., Neubauer, T. A., ter Poorten, J. J., Vonhof, H. B., & Kroonenberg, S. B. (2019). Mollusc biodiversity in late Holocene nearshore environments of the Caspian Sea: A baseline for the current biodiversity crisis. Palaeogeography, Palaeoclimatology, Palaeoecology, 535, [109364]. https://doi.org/10.1016/j.palaeo.2019.109364 Important note To cite this publication, please use the final published version (if applicable). Please check the document version above. Copyright Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons. Takedown policy Please contact us and provide details if you believe this document breaches copyrights. We will remove access to the work immediately and investigate your claim. This work is downloaded from Delft University of Technology. For technical reasons the number of authors shown on this cover page is limited to a maximum of 10. Palaeogeography, Palaeoclimatology, Palaeoecology 535 (2019) 109364 Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo Mollusc biodiversity in late Holocene nearshore environments of the T Caspian Sea: A baseline for the current biodiversity crisis ⁎ ⁎ Sabrina van de Veldea, ,1, Frank P. Wesselingha, ,1, Tamara A. Yaninab, Vitaliy V. Anistratenkoc, Thomas A. Neubauera,d, Jan Johan ter Poortene, Hubert B. Vonhoff, Salomon B. Kroonenbergg a Naturalis Biodiversity Center, P.O. Box 9517, 2300 RA Leiden, the Netherlands b Moscow State University, Faculty of Geography, Leninskie Gory 1, 119991 Moscow, Russia c Department of Invertebrate Fauna and Systematics, Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, B. Khmelnytsky Str. 15, 01030 Kiev, Ukraine d Department of Animal Ecology and Systematics, Justus Liebig University, Heinrich-Buff-Ring 26–32 IFZ, 35392 Giessen, Germany e Department of Zoology (Invertebrates), Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, IL 60605–2496, United States f Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, 55128 Mainz, Germany g Department of Applied Earth Sciences, Delft University of Technology, 2600 GA Delft, the Netherlands ARTICLE INFO ABSTRACT Keywords: The Caspian Sea is an evolutionary island whose rich and endemic fauna have evolved in partial isolation over Biodiversity crisis the past two million years. Baseline studies of pre-20th Century communities are needed in order to assess the Mollusc assemblages severity of the current Caspian biodiversity crisis, which mostly involves invasive species. An inventory of late Pontocaspian biota Holocene shelly assemblages (c. 2000–2500 cal yr BP) from outcrops in and around Great Turali Lake (Dagestan, Invasive species Russia) shows a diverse nearshore community consisting of 24 endemic Caspian species, two invasive species Endemic species and two Caspian native species that lived in a shallow embayment with mesohaline salinities of circa 5–13 psu (parts per thousands). This pre-crisis Holocene Caspian mollusc community serves as a baseline against which modern mollusc diversity measurements can be evaluated. Examination of faunas from similar environments living today and in the past illustrates the dramatic changes in nearshore communities during the 20th Century. Our study identifies a habitat that may have served as a refuge, but that is currently under threat from invasive species. The severity of the Caspian biodiversity crisis is comparable with other well-known biodiversity crises in semi-isolated ecosystems such as the cichlid fish communities of Lake Victoria, Africa. 1. Introduction thousand (‰)). Currently, the Caspian Sea water level is 27 m below global sea level (Arpe et al., 2018). The biggest inland water body on Earth is the Caspian Sea, with a The Caspian Sea has a volatile history of large-scale and rapid lake surface area of 371,000 km2. It is an anomalohaline lake, whose water level change (Badyukova and Kalashnikov, 2009; Fedorov, 1978; level and salinity regimes are determined by a balance of runoff and Ignatov et al., 1993; Kaplin and Selivanov, 1995; Kosarev and evaporation (Kosarev and Yablonskaya, 1994; Krijgsman et al., 2019). Yablonskaya, 1994; Krijgsman et al., 2019; Kroonenberg et al., 2007, The Caspian Sea can be subdivided into three basins: the northern, 2000; Rychagov, 2002; Svitoch, 2014; Varuschenko et al., 1987; middle and southern Caspian basin. Each basin is characterized by its Yanina, 2012), which greatly affected the extent of the lake. During the own temperature, depth, salinity and ecology features and faunas. The last major high-stand in the Late Pleistocene lake levels rose up to 50 m Caspian Sea is disconnected from the open ocean, and various rivers above global sea level (77 m above current Caspian Sea water level), contribute to the inflow of fresh water to the basin. Most of the water and an overflow gateway existed north of the Caucasus towards the (80%) derives from the Volga River, resulting in a strong north-south Black Sea (early Khvalynian transgression: Chepalyga, 2007; Yanina, salinity gradient in the lake (Kostianoy et al., 2005). Near the mouth of 2014). The major cause of the transgression event was the surface the river the salinity is 0 psu, the average of the rest of the basin is runoff increase from the catchment area during the period of degla- around 11–13 psu (practical salinity unit: dissolved salts in parts per ciation (Arslanov et al., 2016; Sorokin et al., 2018). In contrast, at the ⁎ Corresponding authors. E-mail addresses: [email protected] (S. van de Velde), [email protected] (F.P. Wesselingh). 1 Frank P. Wesselingh and Sabrina van de Velde are joint first author. https://doi.org/10.1016/j.palaeo.2019.109364 Received 11 June 2019; Received in revised form 2 September 2019; Accepted 2 September 2019 Available online 07 September 2019 0031-0182/ © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/). S. van de Velde, et al. Palaeogeography, Palaeoclimatology, Palaeoecology 535 (2019) 109364 time of the last big regression in the early Holocene (the Mangyshlak (Fig. 1) located south of Makhachkala along the middle Caspian coast of regression: Bezrodnykh and Sorokin, 2016; Yanina, 2014) the level of Dagestan (Russia). The Turali fauna provides a baseline for the pre- the Caspian Sea was about 100 m below the global sea level (73 m crisis nearshore Caspian community, which serves as a reference point below the current Caspian Sea water level). The extreme lowstand of for comparison with present-day communities. By investigating the the Mangyshlak has been ascribed to the colder, more continental cli- depositional environment and documenting the composition of the matic conditions during the Boreal (Arslanov et al., 2016). During the fauna we aim to provide a habitat-constrained biodiversity baseline for late Holocene two additional minor highstands were reached; −25 m the composition of shallow-water mollusc faunas prior to the drastic (compare to −27 m of present-day Caspian Sea) around 2600 cal yr BP, alterations that took place in the 20th Century. and −26 m during the Little Ice Age (Kroonenberg et al., 2007). The Derbant regression during the Warm Medieval period corresponded to a 2. Study area lowstand of around 32 m (Kroonenberg et al., 2007). Coinciding with those huge changes, the Caspian endemic fauna has 2.1. Geographic context undergone a protracted series of diversifications and extinctions during the Quaternary, including several major turnover events (Krijgsman The middle Caspian Basin is a deep (maximum depth 788 m), well- et al., 2019; Nevesskaja, 2007; Svitoch and Yanina, 2001; Yanina, mixed basin with only minor summer water stratification resulting in 2014). The last natural turnover event of the Caspian Sea biota con- rather uniform salinities across the entire depth range. Salinities are curred in the early Holocene during the Mangyshlak regression typically about 11–13 psu, apart from deltaic areas of rivers draining (Krijgsman et al., 2019: 10–8 ka) when the Khvalynian fauna became the north-eastern Caucasus where salinities can be locally depressed. replaced by the late Holocene Novocaspian fauna. The pre-20th Century The coastal morphology of the western shore of the middle Caspian Novocaspian faunas (< 7 ka) are characterized by the abundance of Basin is largely determined by wave-action, rapid sea-level change, endemic cardiid and dreissenid bivalve species (of the genera Didacna, tectonic uplift, as well as local input of terrigenous erosive products Monodacna, Adacna, Hypanis and Dreissena) and endemic hydrobiid from the Caucasian hinterlands. During the