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Web Ecology An open-access peer-reviewed journal
Web Ecol., 17, 1-7, 2017
https://doi.org/10.5194/we-17-1-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
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24 Jan 2017
Salt tolerance's toll: prolonged exposure to saline water inflicts damage to the blood cells of dice snakes (Natrix tessellata)
Vanya Koleva1, Yurii Kornilev2,3, Ivan Telenchev4, Simeon Lukanov5, Berna Hristova6, and Nikolay Natchev1,3 1Department of Biology, Faculty of Natural Science, Shumen University, 115, Universitetska St, 9700 Shumen, Bulgaria
2National Museum of Natural History, Sofia, 1 Tsar Osvoboditel Blvd., 1000 Sofia, Bulgaria
3Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Althanstraße, 1090 Vienna, Austria
4Department of Ecology and Environmental Protection, Faculty of Biology, Sofia University, 9 Dragan Tzankov Blvd., 1000 Sofia, Bulgaria
5Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, Blvd. Tzar Osvoboditel 1, 1000 Sofia, Bulgaria
6Department of Organic Chemistry and Technology, Faculty of Natural Science, Shumen University, 115, Universitetska St, 9700 Shumen, Bulgaria
Abstract. Dice snakes (Natrix tessellata, Laurenti, 1768) inhabit oligohaline and brackish waters along the Bulgarian Black Sea coast, where they often forage at sea. Under these conditions, this species should tolerate highly variable blood plasma sodium concentrations for extended time periods, but the effect of high sodium concentrations to blood cell morphology and physiology is largely unknown. In this experiment, we placed adult dice snakes in waters with different salinity for 84 h, representing the three typical saline concentrations in which dice snakes live and forage: 0.2 ‰ NaCl, fresh water, 16 ‰ NaCl, Black Sea water and 36 ‰ NaCl, World Ocean water. We collected blood through cardiocentesis after exposure to each treatment and used Giemsa's solution for staining the formed elements. We registered numerous nuclear abnormalities (nuclear buds, lobes and blebs) in the blood cells of all investigated specimens. In the snakes placed in the waters with high saline concentration (16 and 36 ‰ NaCl) we found numerous cells with ruptured membranes. These snakes also showed increased mitochondrial activity compared to those in fresh water (1.85 and 2.53 times higher, respectively). Our data suggest that even though dice snakes show a remarkable tolerance to waters with increased salinity, prolonged exposure to it induces significant physiological stress in N. tessellata, which poses a clear limit for their ability to stay in the sea for a long time.

Citation: Koleva, V., Kornilev, Y., Telenchev, I., Lukanov, S., Hristova, B., and Natchev, N.: Salt tolerance's toll: prolonged exposure to saline water inflicts damage to the blood cells of dice snakes (Natrix tessellata), Web Ecol., 17, 1-7, https://doi.org/10.5194/we-17-1-2017, 2017.
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Short summary
Dice snakes live in freshwater but are able to spend prolonged periods in sea water for food foraging. However, it is unclear whether foraging in salty sea water has a physiological cost. Our experimental data suggest that even though dice snakes show a remarkable tolerance to waters with increased salinity, prolonged exposure induces significant physiological stress (increased metabolism, membrane rupture), which should limit their ability to stay in them for long periods of time.
Dice snakes live in freshwater but are able to spend prolonged periods in sea water for food...
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