Heading: 
UDC: 
574.58(282.256.341)

Bacterioneuston Abundance and Physicochemical Properties of the Surface Microlayer of Lake Baikal

Abstract

The aquatic surface microlayer is located at the atmosphere-hydrosphere boundary and occupies 70% of Earth's surface, covering all water bodies. The depth of the surface microlayer is about 50 μm. A special microbial community called neuston is formed there. The total bacterial abundance in the surface microlayer (SML) and underlying waters (UW) of Lake Baikal was studied using epifluorescence microscopy. Physico-chemical features of the surface microlayer of Lake Baikal were revealed for the first time. The SML was sampled throughout Lake Baikal in May-June of 2013 to 2016 and in August of 2013, 2015 and 2016. SML samples were taken from a boat, mainly during calm weather, using Garrett’s metal mesh screen (a diameter of 26.5 cm). The average values of total bacterial abundance in the SML varied through years within a range of (0.93-1.49)×106 cells/mL in May-June and (1.73-2.24)×106 cells/mL in August; in the UW, at a depth about 15-20 cm, there were (0.79 - 0.89)×106 cells/mL in May-June and (1.15-1.4)×106 cells/mL in August. Significant differences and a direct relationship between the total bacterial abundance in the surface microlayer and underlying waters of Lake Baikal in the summer period have been shown. Differences between the chemical composition of the surface microlayer and the subsurface water layer in all studied seasons were revealed. The surface microlayer was enriched with PO43-, total organic carbon and suspended particulate matter as compared with the underlying waters. A direct relationship was found between the numbers of bacteria in the surface microlayer and the suspended particulate matter concentration.

References

Atlas Baykala [Lake Baikal: Atlas]. Omsk, Roskartografiya Publ., 1993. 160 p. (in Russian).
Balashov A. I., Zaitsev Yu. P., Kogan G. M., Mikhailov V. I. K izucheniyu nekotorykh kom-ponentov khimicheskogo sostava vody na granitse okean-atmosfera [A study of some chemical components of sea water at the sea-air interface]. Okeanologiya, 1974, vol. 14, no. 5, pp. 817−822 (in Russian).
Galach’yants A. D., Bel’kova N. L., Sukhanova E. V., Galach’yants Yu. P., Morozov A. A., Parfenova V. V. Taxonomic composition of Lake  Baikal bacterioneuston communities. Microbiology, 2017, vol. 86, no. 2, pp. 241–249.
Maksimov V. V., Schetinina E. V. Microbiological Characteristic of Pelagic Waters of Lake Baikal According to Data of Total Number of Microorganisms. J. of Siberian Federal University. Biology, 2009, vol. 2, no. 3, pp. 263−270 (in Russian).
Mikhailov I. S., Zakharova Yu. R., Galachyants Yu. P., Usoltseva M. V., Petrova D. P., Sakirko M. V., Likhoshway Ye. V., Grachev M. A. Similarity of structure of taxonomic bacterial communities in the photic layer of Lake Baikal’s three basins differing in spring phytoplankton composition and abundance. Doklady Biochemistry and Biophysics, 2015, vol. 465, pp. 413–419.
Nikitin V. M. Bakterioneyston [Bacterioneuston]. In: Ekologiya Yuzhnogo Baikala [Ecology of Southern Baikal]. Irkutsk, Sibirskoye otdeleniye AN SSSR Publ., 1983, pp. 68−77 (in Russian).
Parfenova V. V., Shimaraev M. N., Kostornova T. Ya., Domysheva V. M., Levin L. A., Dryukker V. V., Zhdanov A. A., Gnatovskii R. Yu., Tsekhanovskii V. V., Logacheva N. F. On the vertical distribution of microorganisms in Lake Baikal during spring deep-water renewal. Microbiology, 2000, vol. 69, no. 3, pp. 357–363.
Romanenko V. I., Kuznetsov S. I. Ekologiya mikroorganizmov presnykh vodoemov [Microorganisms Ecology in Freshwater Bodies]. Leningrad, Nauka Publ., 1974. 194 p. (in Russian).
Severo-zapadnaya chast' Chernogo morya: biologiya i ekologiya [North-western part of the Black Sea: biology and ecology]. Kiev, Naukova Dumka Publ., 2006. 703 p. (in Russian).
Shimaraev M. N., Granin N. G. On the stratification and the mechanisms of convection in Lake Baikal. Doklady Akademii nauk SSSR, 1991, vol. 321, no. 2, pp. 381–385 (in Russian).
Agogue H., Casamayor E. O., Joux F., Obernosterer I., Dupuy C., Lantoine F., Catala P., Weinbauer M. G., Reinthaler T., Herndl G. J., Lebaron P. Comparison of samplers for the biological characterization of the sea surface microlayer. Limnology and Oceanography: Methods, 2004, no. 2, pp. 213–225.
Cunliffe M., Whiteley A. S., Newbold L., Oliver A., Schäfer H., Murrell J. C. Comparison of bacterioneuston and bacterioplankton dynamics during a phytoplankton bloom in a fjord meso-cosm. Applied and Environmental Microbiology, 2009, vol. 75, no. 22, pp. 7173–7181.
Cunliffe M., Upstill-Goddard R., Murrell C. Microbiology of aquatic surface microlayers. FEMS Microbiology Reviews, 2011, vol. 35, no. 2, pp. 233–246.
Hörtnagl P., Perez M. T., Zeder M., Sommaruga R. The bacterial community composition of the surface microlayer in a high mountain lake. FEMS Microbiology Ecology, 2010, vol. 73, no. 3, pp. 458–467.
Joux F., Agogué H., Obernosterer I., Dupuy C., Reinthaler T., Herndl G. J., Lebaron P. Microbial community structure in the sea surface microlayer at two contrasting coastal sites in the northwestern Mediterranean Sea. Aquatic Microbial Ecology, 2006, vol. 42, no. 1, pp. 91–104.
Khodzher T. V., Domysheva V. M., Sorokovikova L. M., Golobokova L. P. Methods for monitoring the chemical composition of Lake Baikal water. In: Novel methods for monitoring and managing land and water resources in Siberia. Cham, Springer Publ., 2016, pp. 113–132.
Khodzher T. V., Domysheva V. M., Sorokovikova L. M., Sakirko M. V., Tomberg I. V. Current chemical composition of Lake Baikal water. Inland Waters, 2017, vol. 7, no. 3, pp. 250–258.
Kuznetsova M., Lee C. Enhanced extracellular enzymatic peptide hydrolysis in the seasur-face microlayer. Marine Chemistry, 2001, vol. 73, no. 1–2, pp. 319–332.
Kuznetsova M., Lee C., Aller J., Frew N. M. Enrichment of amino acids in the sea-surface microlayers at coastal and open ocean sites in the north Atlantic ocean. Limnology and Oceanography, 2004, vol. 49, no. 5, pp. 1605–1619.
Obernosterer I., Catala P., Reinthaler T., Herndl G. J., Lebaron P. Enhanced heterotrophic activity in the surface microlayer of the Mediterranean Sea. Aquatic Microbial Ecology, 2005, vol. 39, no. 3, pp. 293–302.
Porter K. G., Feig Y. S. The use of DAPI for identifying and counting aquatic microflora. Limnology and Oceanography, 1980, no. 25, pp. 943–948.
Santos L., Santos A. L., Coelho F. J. R. C., Gomes N. C. M., Dias J. M., Cunha A., Almeida A. Relation between bacterial activity in the surface microlayer and estuarine hydrodynamics. FEMS Microbiology Ecology, 2011, vol. 77, no. 3, pp. 636–646.
Santos A. L., Baptista I., Gomes N. C. M., Henriques I., Almeida A., Correia A., Cunha A. Contribution of chemical water properties to the differential responses of bacterioneuston and bacterioplankton to ultraviolet-B radiation. FEMS Microbiology Ecology, 2014, vol. 87, no. 2, pp. 517–535.
Sarmento H., Casamayor E. O., Auguet J.-C., Vila-Costa M., Felip M., Camarero L., Gasol J. M. Microbial food web components, bulk metabolism, and single-cell physiology of pi-coneuston in surface microlayers of high-altitude lakes. Frontiers in Microbiology, 2015, vol. 6, Article 361, pp. 1–12.
Wetzel R. G., Likens G. E. Limnological analyses. New York, Springer, 2000. 429 p.
Zhang Z., Liu L., Wu Z., Li J., Ding H. Physicochemical studies of the sea surface mi-crolayer: I. Thickness of the sea surface microlayer and its experimental determination. J. Colloid Interface Science, 1998, vol. 204, no. 2, pp. 294–299.
Zhang Z., Liu L., Liu C., Cai W. Studies on the sea surface microlayer. II. The layer of sud-den change of physical and chemical properties. J. Colloid Interface Science, 2003, vol. 264, no. 1, pp. 148–159.

стр. 379
Short text (in English): 
Full text (in Russian):