Paracoenogonimus ovatus (Katsurada, 1914)

Goncharov, S. L. & Soroka, N. M., 2015, The Occurrence of Paracoenogonimus Ovatus (Trematoda, Cyathocotylidae) in Fish of Natural Reservoirs of Mykolaiv Region, Vestnik Zoologii 49 (5), pp. 421-426 : 421-422

THE OCCURRENCE OF PARACOENOGONIMUS OVATUS ( TREMATODA, CYATHOCOTYLIDAE ) IN FISH OF NATURAL RESERVOIRS

OF MYKOLAIV REGION

S. L. Goncharov 1, N. M. Soroka 2

1 Mykolaiv Regional State Laboratory of Veterinary Medicine ,

Lunacharsky, 2 A st., Mykolayiv, 5400 Ukraine

E-mail: [e-mail]

2 National University of Life and Environmental Sciences of Ukraine,

Polkovnyka Potekhina, 16 st., Kyiv, 03030 Ukraine

The Occurrence of Paracoenogonimus ovatus ( Trematoda, Cyathocotylidae ) in Fish of Natural Reservoirs of Mykolaiv Region. Goncharov, S. L., Soroka, N. M. — The article presents the original findings of Paracoenogonimus ovatus (Katsurada,1914) in fish in the Southern Bug and the Inhul rivers in Mykolaiv Region in 2012–2014. The roach ( Rutilus rutilus ), silver bream ( Blicca bjoerkna ), bream ( Abramis brama ), crucian ( Carassius gibelio ), rudd ( Scardinius erythrophthalmus ), pike ( Esox lucius ), pikeperch ( Sander lucioperca ) were found to be infected with metacercariae of P. ovatus . Metacercariae of P. ovatus are described based on the original material. The highest prevalence of infection was observed in the roach, 82.3 %, the pike was infected in the less degree, with prevalence of 15.3 %. The infection intensity was highest in the roach, up to 247 specimens; that of the pikeperch was the lowest — 17 specimens. The highest occurrence of P. ovatus was observed in the parts of the river Southern Bug in Zhovtnevy, Mykolaiv, Novoodesky Districts, whereas in Voznesenky, Pervomaysky Discticts and in the city of Mykolaiv the occurrence was the lowest. In the area of the river Inhul the parasite was observed mostly in the waters of Bashtansky District in Mykolaiv Region.

K e y w o r d s: occurrence, Paracoenogonimus ovatus , fish, intensity of infection, extensity of infection, natural reservoir, Mykolaiv Region.

Распостранение параценогонимоза ( Trematoda, Cyathocotylidae ) в природных водоемах Николаевскойобласти.ГончаровС.Л.,СорокаН.М.— В статьеприведеныданныераспространения в акваториях рек Южный Буг и Ингул относительно нового, трематодозного паразитарного заболевания рыб — параценогонимоза, которое ранее на территории Николаевской области не регистрировалось. Исследования проводили в 2012 –2014 гг. Приведены исторические факты изучения трематоды P. ovatus . Установлена инвазированость метацеркариями P. оvatus различной степени таких видов рыб, как тарань, густера, лещ, карась, красноперка, щука, судак. Наиболее пораженной была тарань, экстенсивность инвазии составила 82,3 %, наименее инвазированым оказался судак, экстенсивность инвазии которого составила 15,3 %. Интенсивность инвазии была максимальной у тарани — 247 экз., и наименьшей у судака — 17 экз. Наибольшее распространение отмечено на участках реки Южный Буг в Октябрьском, Николаевском, Новоодесском районах, в меньшей степени отмечено в Вознесенском, Первомайском районах и г. Николаеве. На участке реки Ингул концентрация инвазии наблюдалась преимущественно в акваториях Баштанского района Николаевской области.

К л ю ч е в ы е с л о в а: распространение, Paracoenogonimus ovatus , рыба, интенсивность инвазии, экстенсивность инвазии, естественный водоем, Николаевская область.

Many infection agents, previously considered as safe and, therefore, poorly studied, are rather pathogenic in modern industrial fish farming and can yield significant economic losses. Accordingly, they require urgent examination ( Mineeva, 2013). Fish raised in pond farms (carp, common carp, grass carp, silver carp, etc.) are mostly free from larval helminthes pathogenic for humans and animals. On the contrary, commercial fish, mollusks, crustaceans are potential carriers of 27 species of helminthes that are dangerous to humans ( Davidov, 2003). Fisheries established in natural reservoirs (lakes, rivers, ponds) also require investigation of parasitic diseases of fish. However, their control in these reservoirs is limited. The knowledge of the biology and the spread of pathogenic parasitic infections contribute to the development of effective control techniques resulting in the improvement of epizootic status of fish stock and the reservoir itself ( Bauer, 1984). Trematodoses may cause significant economic losses because of death of fish or its poor salable condition for both domestic and foreign fish market (Ginetsinskaya, 1959). Trematode P. ovatus belongs to pathogenic agents that pose a potential threat to fish and human health.

Paracoenogonimus ovatus parasitizes the intestine of piscivorous birds, mammals, sea mammals and humans ( Sudarikov, 2006). Metacercariae inhabit mainly fish muscular tissue. They can also be found in the fins, heart, gills, liver, kidney, ovary, vitreous body of the eye and brain, but much less frequently (Ginetsinskaya, 1959).

Metacercariaeof P. ovatus are highlypathogenic for fish larvae; they can reach intensity of up to several thousand specimens and, therefore, may be dangerous for mammals consuming infested fish (Ginetsinskaya, 1959; Linnik, 1988).The extreme spread of the parasite was spotted in reservoirs of Russia, Poland, Germany, the Netherlands, Romania, Hungary, Finland, Latvia, Norway, Azerbaijan, Czech Republic, Slovakia, Belarus, etc. ( Davidov, 2003; Komiya, 1938). According to the results of research, the disease is most common both innatural and in artificial reservoirs in Russia (Ginetsinskaya, 1959).

At the same time, there are no data on the distribution of P. ovatus on the territory of Ukraine.

F. Katsurada (1914) first described a new species of trematodes, P. ovatus , which he isolated from the gastrointestinal tract of the laboratory mice infected with metacercariae from the muscular tissue of carp caught in the Elbe and the Alster rivers in Germany. There after, this species was described by L. Szidat during the examination of birds of the Baltic Sea ( Szidat, 1936). J. Komiya studied the parasite’s life cycle, and first pointed to the possible intermediate and final hosts of P. ovatus ( Komiya, 1938) .

In Ukraine, P. ovatus was first described by Markevich in 1951 in the mouths of the Dnieper and the Tiszaunder the name of Diplostomulum hughesi Markevitch, 1934 . Metacercariae were found in the muscular tissue of pike ( Esox lucius ) ( Markewitch, 1951). On the territory of the former USSR, the species was investigat- ed by T. Ginetsinskaya, whose major scientific interest was to determine the systematic position and taxonomic affiliation of this species based on morphological characteristics. The author also studied the clinical manifestations of paracoenogonimosis and noted that the processes of infiltration and migration were accompanied by multiple hemorrhages, which likely caused rapid (within a few hours) death of infected fry. In the author’s opinion, the formation of metacercariae lasted 30 days, with metacercariae being placed in spherical cysts with transparent hyaline membrane. The cysts had an average size of 0.376 mm (Ginetsinskaya, 1959). J. Komiya made an assumption that mollusks Viviparus viviparous and Viviparus contectus were involved into the life cycle of P. ovatus ( Komiya, 1938) . At the same time, according to O. Serbina, parthenits of P. ovatus were found in Bithynia tentaculata from the Upper Ob in Western Siberia ( Serbina, 2002). Carp, gobies, salmon, pike, herring, silverside, stickleback and even Syngnathidae were reported as hosts of P. ovatus ( Sudarikov, 2006) .

The aim of our study was to examine natural reservoirs of the Southern Bug and the Inhul rivers in Mykolayiv Region, to reveal P. ovatus and to determine possible causes of its spread .