CHANGES IN THE HYDROECOLOGICAL STATUS INDICATORS OF THE TYLIHUL ESTUARY AFTER THE RECONSTRUCTION OF THE SEA-CONNECTING CHANNEL
Abstract
In 2016-2017, the connecting channel “Tylihul Estuary - Black Sea” was reconstructed with the aim of improving the hydroecological status of the estuary by increasing its external water exchange with the sea. This article is devoted to analyzing changes in the hydroecological status of the estuary based on a set of hydrological, hydrochemical, and hydrobiological characteristics of its ecosystem that occurred after the reconstruction of the connecting channel. The comparative analysis is based on data obtained from monthly hydroecological monitoring of the estuary during 2025, as well as retrospective data on its hydroecological characteristics collected prior to the channel reconstruction. It was established that the reconstruction of the connecting channel did not achieve its main objective, as no decrease in water salinity in the estuary occurred as a result of intensified bidirectional water exchange with the sea. Concentrations of mineral and organic nitrogen and phosphorus in the estuary waters increased compared to the period before the reconstruction. Phytoplankton species diversity decreased, with a predominance of marine species; fish species diversity and catches in the estuary also declined. The state of the ichthyofauna and fish productivity of the estuary did not improve and remain unstable. The main reason for this is the discrepancy between the actual morphometric characteristics of the channel and the design specifications, non-compliance with established operational rules, and additionally, the construction of a new bridge crossing over the channel, which hindered water exchange between the estuary and the sea. By the end of June 2025, the average cross-sectional area of the channel was 2.8 times smaller than the design value, and the average depth was 2.2 times less than the design specification (2.0 m and 0.91 m, respectively). The general conclusion is that the reconstruction of the “sea-estuary” connecting channel carried out in 2016-2017 did not achieve its intended goal. Recommendations are provided for measures to improve the current hydroecological status of the Tylihul Estuary.References
Tuchkovenko, Yu.S., Loboda, N.S. (eds). (2014). Vodni resursy tahidroekolohichnyi stan Tylihulskoho lymanu [Water resources andhydroecological conditions of the Tyligulskiy Liman Lagoon]. Odessa State Environmental University. Odesa: TES Publ. (in Ukr.)
Gubanova O., Tuchkovenko Y., Khokhlov, V., Stepanenko, V., & Baggett, S. (2015). The Management Story of Tyligulskyi Liman Lagoon. In: Lillebø, A.I., Stålnacke, P. & Gooch, G.D. (eds.), Coastal Lagoons in Europe: Integrated Water Resource Strategies. London, UK: IWA Publishing, pp. 87–96.
Tuchkovenko, Yu. S., Khokhlov, V. M., Loboda, N. S., Kushnir, D. V., Serga, E. M. (2022). Vplyv zmin klimatu na hidrolohichnyi i hidroekolohichnyi rezhymy lymaniv pivnichno-zakhidnoho Prychornomoria [Climate change impact on hydrological and hydroecological regimes of lagoons on the North-Western Black Sea coast]. In: Tuchkovenko, Yu.S. (ed.). Odesa: Odessa State Environmental University. (in Ukr.)
Rozengurt, M.Sh. (1974). Gidrologiya i perspektivy rekonstruktsii prirodnykh resursov odesskikh limanov [Hydrology and prospects for the reconstruction of the natural resources of the Odessa limans]. Kyiv: Naukova dumka. (in Russ.).
Tuchkovenko, Y.S., Adobovskiy, V.V., Tuchkovenko, O.A. (2014). [Characteristics of variability in thermohaline conditions of the Tyligulskyi Liman lagoon in the present period]. Bulletin of Odessa State Environmental University, 17, pp. 197-204. (in Russ)
Tuchkovenko, Yu.S., Bogatova, Yu.I., Tuchkovenko, O.A. (2015). [Contemporary hydrochemical regime of Tyligulskiy liman]. Bulletin of Odessa State Environmental University, 19, pp. 126-133. (in Russ)
Tuchkovenko, Y., Khokhlov, V., Loboda, N. (2022). [Climate change impact on water balance of quasi-closed lagoons in the North-Western Black Sea coast]. Ukrainian Hydrometeorological Journal, 29, pp. 32-47. (in Ukr.) https://doi.org/10.31481/uhmj.29.2022.03
RD 52.10.243-92. (1992). Nastanova z khimichnoho analizu morskykh vod [Marine Water Analysis manual]. (in Russ). Available at: https://online.budstandart.com/ua/ catalog/doc-page.html?id_doc=77071 (Accessed: 10.03.2026)
RD 52.24.420-2006. (2006). Biokhimichne spozhyvannia kysniu u vodakh. Metodyka vykonannia vymiriuvannia skliankovym metodom [Biochemical oxygen demand in waters. Methodology for measuring by the glass method]. (in Russ). Available at: https://online.budstandart.com/ua/catalog/doc-page.html?id_doc=76349 (Accessed: 10.03.2026)
Tablicy rastvorimosti kisloroda v morskoj vode [Tables of oxygen solubility in seawater] (1976). Leningrad: Gidrometeoizdat. (in Russ)
Moncheva S., Parr B. (2014). Black Sea Monitoring Guidelines. Phytoplankton. Available at: http: www.noelsporttraits.com/index.php?main_page&id=28&chapter=50 (Accessed: 10.03.2026)
Bryantseva, Yu.V., Lyakh, A.M., Sergeeva, A.V. (2005). Raschet ob’emov i ploshchadey poverkhnosti odnokletochnykh vodorosley Chernogo morya [Calculation of volumes and surface areas of unicellular algae of the Black Sea]. Sevastopol, 2005. (in Russ)
Tsarenko, P., Wasser, S. and Nevo, E. (eds). (2006). Algae of Ukraine: diversity, nomenclature, taxonomy, ecology and geography. Vol. 1. Cyanoprokaryota, Euglenophyta, Chrysophyta, Xanthophyta, Raphidophyta, Phaeophyta, Dinophyta, Cryptophyta, Glaucocystophyta and Rhodophyta. Rugell: Gantner Verlag.
Tsarenko, P.M., Wasser, S., Nevo, E. (eds). (2009). Algae of Ukraine: diversity, nomenclature, taxonomy, ecology and geography. Vol. 2. Bacillariophyta. Rugell: Gantner Verlag.
Tsarenko, P.M., Wasser, S., Nevo, E. (eds). (2011). Algae of Ukraine: diversity, nomenclature, taxonomy, ecology and geography. Vol. 3. Chlorophyta. Rugell: Gantner Verlag.
Electronic database WoRMS (World Register of Marine Species). Available at: www.http//marinespecies.org (Accessed: 18.02.2026)
Zinova, A.D. (1967). Opredelitel zelyonyh, buryh i krasnyh vodoroslej yuzhnyh morej SSSR [Identification manual of green, brown and red algae of the Southern Seas of the USSR]. Moskva-Leningrad: Nauka. (in Russ)
Kalugina-Gutnik, A.A. (1975). Fitobentos Chyornogo moray [Phytobenthos of the Black Sea]. Kyiv: Naukova Dumka. (in Russ.)
Minicheva G., Afanasyev D., Kurakin A. (2020). Black Sea Monitoring Guidelines. Macrophytobenthos. Dnipro: Seredniak T.K.
Guiry M.D., Guiry G.M. (2026). AlgaeBase. World-wide electron. publ. Nat. Univ. Ireland, Galway. Available at: https://www.algaebase.org (Accessed: 05.02.2026)
IPNI (2026). International Plant Names Index. Publ. Int. Roy. Bot. Gardens Kew, Harvard Univ. Herbaria & Librar. and Austral. Nat. Herbar. Available at: http://www.ipni.org. (Accessed: 05.02.2026)
Kovtun, O.A. (2012). Fitobentos Tiligulskogo limana (Chernoe more, Ukraina) [Phytobentos of the Tilihul Estuary (Black Sea, Ukraine)]. LAP Saarbrucken, Deutschland: Lambert Academic Publishing. (in Russ.)
Midway, S.R., Hasler, C.T., Chakrabarty, P. (eds.). (2022). Methods for Fish Biology. 2nd ed. Bethesda, Maryland: American Fisheries Society.
Institute of Fisheries (1998). Metodyka zboru i obrobky ikhtiolohichnykh ta hidrobiolohichnykh materialiv [Methodology for collecting and processing ichthyological and hydrobiological materials]. Kyiv: Institute of Fisheries.
Demchenko, V., Petrovych O. (eds.) (2020). Metodychni rekomendatsii z orhanizatsii inventaryzatsii, otsinky, monitorynhu vodno-bolotnoho uhiddia mizhnarodnoho znachennia ta skladannia informatsiinoho opysu [Methodological recommendations for organizing inventory, assessment, monitoring of wetlands of international importance and compiling an information description]. Kherson: Publishing House "OLDI-PLUS"
Tuchkovenko, Yu.S. (scient. chief). (2014). Kompleksne upravlinnia vodnymy resursamy Tylihulskoho lymanu ta yoho hidroekolohichnym stanom v umovakh antropohenoho vplyvu i klimatychnykh zmin: Zvit pro NDR zakliuchnyi. DR № 0113U000696 [Integrated management of water resources in the Tyligulskiy Liman Lagoon and its hydroecological conditions in the context of anthropogenic influence and climate change: Final Report. SR 0113U000696]. Odessa State Environmental University. Odesa. (in Ukr.)
Tuchkovenko, Yu.S. (scient. chief). (2015). [Description of the modern hydrochemical and hydrological conditions of the lagoon, development of recommendations for its improvement. Part of technical-economic calculation on the project “Development of designing estimates for reconstruction of the connecting channel between the Tyligulskyi Liman Lagoon and the Black Sea in the area of Kominternivskyi district of Odesa Region”: Final Report. SR 0115U006850]. Odessa State Environmental University. Odesa. (in Ukr.)
Minicheva, G.G. (scient. chief). (2015). [Characteristics of the modern hydrobiological regime of the lagoon, development of recommendations for maintaining biological diversity and good ecological condition. Part of technical-economic calculation on the project “Development of designing estimates for reconstruction of the connecting channel between the Tyligulskyi Liman Lagoon and the Black Sea in the area of Kominternivskyi district of Odesa Region”: Final Report], Institute of Marine Biology of the NAS of Ukraine, Odesa. (in Ukr.)
Snigirov, S., Bushuev, S., Chernikov, G., Kovtun, O., Zamorov, V., Kurakin, A. (2017). [Ichthyofauna of the Tiligulskiy Lyman (Estuary) in the beginning of XXI century]. Ukrainian Journal of Ecology, 7(4), 35–45. (in Ukr.). https://doi.org/10.15421/2017_84
Zaitsev Yu.P., Aleksandrov B.G., Minicheva G.G. (Eds.) (2006). Severo-zapadnaja chast' Chernogo morja: biologija i jekologija [The North-Western part of the Black Sea: Biology and Ecology]. Kiev: Naukova Dumka, 2006, pp. 358–370. (in Russ.)
Shekk, P.V. (2015). [Characteristics of the state of ichthyofauna and the prospects of fishery use of the Tiligulskiy liman]. Bulletin of Taras Shevchenko National University of Kyiv: Biology, 3 (68), pp. 54-60.
Snigirova, A.A., Bogatova, Yu.I. (2020). [Phytoplankton of Tiligulsky liman in conditions of change of salt regime]. Marine ecological journal, 2, pp. 31-38 (in Ukr.). https://doi.org/10.47143/1684-1557/2020.2.04
Tuchkovenko Y.S., Kushnir D.V., Loboda N.S. (2015). [Estimation of the influence of water exchange with the sea conditions on the water level and salinity variability in the Tyligulskyi Liman lagoon]. Ukrainian Hydrometeorological Journal, 16, pp. 232-241. https://doi.org/10.31481/uhmj.16.2015.30 (in Russ.)
Ministry of Fisheries, USSR. (1990). Hranychno dopustymi znachennia pokaznykiv yakosti vody dlia rybohospodarskykh vodoim. Zahalnyi perelik HDK i OBRV shkidlyvykh rechovyn dlia vody rybohospodarskykh vodoim: (№12-04-11 chynnyi vid 09-08-1990) [Maximum permissible values of water quality indicators for fishery reservoirs. General list of MPC and OBRV of harmful substances for water of fishery reservoirs: (№12-04-11 effective from 09-08-1990]. (in Ukr.)
Redfield, A.C., Ketchum, B.H., Richerds, F.A. (1963). The influence of organisms on the composition of sea water. The Sea. Ed. M. N. Hill, No 4, 2, pp. 26-49.
Zotov, A.B., Bogatova, Yu.I. (2012). [Influence of the variability of organic matter content on phytoplankton abundance of the Tiligulskiy liman during the spring-summer period]. Scientific Bulletin of Uzhgorod University, 32, 24-34. (in Russ.)
