Ecological Aspects In Functioning Of The Fish Nursery Khtmo In Connection With The Shabolatsky Estuary Ecosystem Restoration
ECOLOGICAL ASPECTS IN FUNCTIONING OF THE FISH NURSERY KhTMO IN CONNECTION WITH THE SHABOLATSKY ESTUARY ECOSYSTEM RESTORATION
V.N. Turkulova1, N.V. Novoselova2, S.N. Kosyak1
1Southern Scientific Research Institute of Marine Fisheries
and Oceanography (YugNIRO), Kerch, Ukraine
2Self-Financing Territorial Inter-Industrial Corporation
(KhTMO), Odessa, Ukraine
One of the founder of the science of ecology Yu. Odum (1975) noted the fact that «important commercial species as well as species – objects for sport fishing depend, to a large extent, on estuaries, that providing of the most significant economic justification for conservation of these habitats». In this connection the question of conservation of estuaries-lagoons and the coastal area of the sea, their biodiversity, has always been rather actual and in recent decades in particular due to the increased anthpogenic impact resulting, as a rule, in worsening of reproduction conditions, real threat for conservation of their specific diversity. In this aspect the distinctive «model» of the water area – «victim» of the human economic activity may be the Shabolatsky estuary. It belongs to the group of estuarine lagoons between the rivers of Danube and Dniester, being a lagoon of periodically open type. The estuary is constantly connected with the Dniester estuary by two fish release canals and periodically (in spring and autumn) with the sea. It is separated from the sea with the sand split 17 km long, its area is equal to 2,5-2,7 hectares, maximum depth 3,0 m, the average one 1,1 m. Hydrochemical regime is depended in the north-western part upon the impact of the fresh waters from the Dniester estuary and Akkembetsky bay, on the other hand, upon the impact of sea water masses in the south-western part. In this connection salinity varies from 4 to 22%. Along the southern coast of the water body there is a number of settlements, including sanatoria. One of them named Sergeevka, mud resort, has the greatest anthropogenic pressure.
The analysis of the state of the estuary hydrologo-hydrochemical regime, ichthyofauna specific composition and abundance, food supply for the recent
30 years (60s - 90s) revealed, that great changes took place, connected, in opinion of the authors (Shekk, Rovnin, 1991), with anthropogenic impact. Hydrologo-hydrochemical composition of water bodies have changed – as compared with 60s the salinity reduced nearly 1,5 times. The content of organic substance in the estuary has become much higher than in the water of the Black Sea. Specific composition of the main groups of organisms for feeding has faced changes. Zooplankton production reduced as much as 1,5-3times. Fish productivity in 60s made 7,1 kg/ha, in 70s - 1,5 kg/ha, in early 90s - 0,95 kg/ha. Freshwater fishes became predominant, migrating for feeding from the Dniester estuary.
Shabolatsky estuary suffered the greatest losses after the ecological disaster in late June 1992. One of the authors of its article – V.N. Turkulova – was an eye-witness of this disaster. Health resort Sergeevka discharged sewage – a mixture for washing mud tanks - into the estuary. The consequences of this act were analyzed in details in the article of Volya, Druchin, 1999, ODOYugNIRO specialists at that time, taking part in the investigation of this accident. The content of trivalent chromium increased ten and even fifteen times, phosphorus acid was found that proved the presence of chrome mixture, the content of detergents increased as much as thirty times in the water from the estuary. The total amount of the mixture discharged into the estuary, according to the experts’ assessment, exceeded 10000 tons. This resulted in reduction of diluted in water oxygen down to 0-0,2 mg/l, transparency from 2m to 0, death of about 90% of all bottom organisms, all the zooplankton, plants, mussel farms, brood stock of Pacific mullet kept in nurse-pond in the estuary. At present Shabolat ecosystem is slowly restoring.
The complex of nature protective measure counterbalance the negative impact of human economic activity on water body biocenosis. These are hydromelioration measures, namely maintenance of canal, release of juveniles of valuable commercial fish species into the estuary, grown under artificial conditions.
From the moment of the ecological disaster canals have not been operated. The absence of the direct connection with the sea resulted in increased salinity up to 29%, and smell of hydrogen sulphide was felt not only in the depth but in the coastal zone. According to our data in 1995 the average abundance of zooplankton made 2000 individuals/m3, the average biomass 300mg/m3. Since 1996 four fish canals have been operated in the estuary. Since this time salinity has not exceeded 20% in summer and has not fallen lower 12% in winter. Oxygen content did not reduce lower 5-6 mg/l.
In qualitative and quantitative composition changes took place – there appeared new types of «Black Sea» and «Caspian» complexes. Zooplankton abundance increased up to 4000 ind./m3, average biomass - 600 mg/m3. In 1998 firstly for many years there was registered spring-summer outburst of zooplankton abundance and biomass - 1100 mg/m3 and 150 thousand mg/m2 – feeding zoobenthos.
Thus, regular operation of canals (our observation were made in the area of fish nursery KhTMO) contributed to improvement of the estuary food supply, owing to this increased aboriginal fish productivity may be expected as well as successful feeding of incoming fish – Pacific mullet, Black Sea mullets.
Since 1987 in the area of fish release canals of Pilot Mullet plant EKZ (Russian acronym) on the Budak split, settlement Kurortnoye area, a line for reproduction of Pacific mullet began to be operated. Since 90s specialized fish nursery has been under the authority of KhTMO. YugNIRO and ODOYugNIRO personnel in the shortest time (1988-90) developed biotechnology for commercial production of Pacific mullet juveniles. The amount of viable juveniles increased from 12 thousand species to 3 million individuals from 1988 till 1998. Produced juveniles were released for foraging growth into the estuary and for commercial growth – into ponds. All these years brood stock from Molochny Estuary (the Sea of Azov), from the Kerch strait, from Khadzhibeysky Estuary, Palievsky Bay was used. In 2000 we have used for the first time Pacific mullet brood stock, that came for the pre-spawning feeding into Shabolatsky estuary. After hypophysis stimulation we obtained 2 million 840 thousand eggs. There were released 500 thousand of juveniles at the age of 12 days for foraging growth in Shabolatsky estuary (act of 29.06.2000). After adaptation to the water of low salinity 13 thousand fingerlings at the age of 25 days (after metamorphosis) were released into fresh water pond for commercial growth.
Since 1997 YuNIRO scientists have carried out experiments at KhTMO in order to obtain viable juveniles of one of the most valuable Black Sea fish species – Black Sea turbot. This species has a great value at the world market, as it has particular nutritive and delicious value. In European countries the analog of the Black Sea turbot is grown – so-called turbot. The attention of Russia and Ukraine has increased greatly to the Black Sea turbot, biotechnology of its cultivation is similar to European one, but has some specific features. It is planned to carry out joint studies of Ukraine and Turkey in order to grow viable juveniles of the Black Sea turbot. In 1997-1998 at fish nursery KhTMO we grew and released into estuaries – Shabolatsky and Tiligulsky, as well as into the coastal part of the sea 20 thousand juveniles at the age of 10, 15, 70 and 120 days, 4-6 and 60-80 mm long, weight 1 and 3,8mg, 1 and 6 g, respectively. It is planned to expand the spectrum of growing species on the expense of such species as flounder, Black Sea mullets – gray mullet and leaping gray mullet.
The normal operation of fish nursery and fish release canal, increase of amount of juveniles grown are depended upon some problems. The most important of them is financing. KhTMO is a private company, carrying out, in fact, governmental nature-protective program. Support of the nursery by all the ecological, inspection and other governmental services is required.
Restoration of the ecosystem in the unique water body – Shabolatsky Estuary is our common duty.
References
1. Odum Yu. The bases of ecology. - Moscow: Mir, 1975. - P. 620.
2. Dimitriev Ya.I. Use of the Black Sea estuaries for fishery purposes. – Kishinev: Shtiintsa, 1979. - P. 176.
3. Shekk P.V., Rovnin A.A. Prospects in increase of fish productivity of saline estuaries in the north-western Black Sea by the way of fish stocking with marine fish juveniles //Collection of scientific works of VNIRO. - Moscow, 1991. - P. 4-20.
4. Maslova О.N., Razumeev Yu.V., Dergaleva Zh.T. Marine pisciculture: possibilities and reality. Fisheries, №3, 1998, P. 54-56.
5. Turkulova V.N., Novoselova N.V., Krakatitsa V.V., Kosyak S.N. Cultivation of Black Sea turbot (PSETTA MAEOTICA MAEOTICA PALLAS) under the conditions of lower Dniester (Shabolatsky estuary)//Theses of the International Conference. - Kishinev, 1998. - P. 166-170.
6. Turkulova V.N., Novoselova N.V., Krakatitsa V.V., Kosyak S.N. Prospects of increase in specific diversity of ichthyofauna in the area of lower Dniester in connection with the functioning of fish nursery KhTMO. Theses of the International Conference. - Kishinev, 1999, P.229-230.
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