Monitoring of sanitary and hygienic state of water bodies in the republic of Dagestan for egg contamination of intestinal cestodes Triaenophorus Nodulosus (Pallas, 1781) and Triaenophorus Crassus (Forel, 1868)

Authors monitored the sanitary and hygienic state of the river and pond basin of the Republic of Dagestan for contamination of the cestodes Triaenophorus nodulosus (Pallas, 1781) and Triaenophorus crassus (Forel, 1868) eggs. The water pollution of 25 rivers and pond water bodies of Dagestan with eggs of the cestodes Triaenophorus nodulosus (Pallas, 1781) and Triaenophorus crassus (Forel, 1868) was studied in winter, spring, summer and autumn in control sections by researching 2 500 water samples using conventional methods in the laboratory of invasive diseases of animals and birds. For the presence of eggs of the cestodes Triaenophorus nodulosus (Pallas, 1781) and Triaenophorus crassus (Forel, 1868), using conventional methods in different seasons (winter, spring, summer and autumn), 100-200 samples of water and silt of vegetation of pond reservoirs in natural zones were examined. According to the results of the sanitary and hygienic examination of water and silt of natural and pond water bodies of the Republic of Dagestan for the contamination of the cestodes Triaenophorus nodulosus (Pallas, 1781) and Triaenophorus crassus (Forel, 1868) eggs, it is possible to state moderate and high levels of water pollution with eggs of these cestodes species. According to the sanitary and hygienic state, natural and pond water bodies of the Republic of Dagestan in all natural and climatic zones are unsuccessful foci of trienophorous fish invasion by eggs of the Triaenophorus nodulosus Triaenophorus (Pallas, 1781) and Triaenophorus crassus. (Forel, 1868).

Influence of Triaenophorus nodulosus invasion on morphobiological parameters of European perch (Perca fluviatilis L.) in Shatsk National Nature Park reservoirs

It was conducted comprehensive ichthyological and ichthyopatological research of European perch (Perca fluviatilis L.) populations in lakes of Shatsk National Nature Park and the impact of Triaenophorus nodulosus invasion on its size, weight and reproductive ability. Morphometric analysis, absolute and relative fecundity of fish were determined by the methods generally accepted in ichthyology. Clinical examination of fish (2,225 specimens, including European perch -1650 specimens) was performed during control catches. Simultaneously, the weight, size, and age of the fish were determined. Morphometric analysis was performed on 120 specimens of perch with the length of 104.4-194.8 mm and the weight of 16.4-177.6 g. Pathoanatomic autopsy of the fish was performed in the field and laboratory conditions. Parasitological studies were performed by the method of incomplete parasitological analysis. The extent and intensity of the invasion were determined. When conducting research on the parasitofauna of native fish species in the lakes of the Shatsk National Nature Park, it was found their infestation with helminths of various systematic positions (Triaenophorus nodulosus, Khawia sinensis, Raphidascaris. acus, and Philometroides lusiana). Perch was the most infected with the helminths. The invasion caused by the plerocercoid of Cestoda T. Nodulosus was the most intensive (18.2-56.3%, depending on the reservoir). There was a significant difference in the measurements of non-infested and infested with T. nodulosus fish individuals of the same age, we also registered significant lag in growth and a decrease in body weight among the infested specimens. A steady trend towards a decrease in fecundity parameters was also observed in infested fish. Thus, in non-infested individuals of 4-year perch, the highest individual absolute fecundity (IAF) was 6.7 thousand eggs against 3.1 thousand eggs in the infested perch (Lucimer lake). The lowest IAF – 3.9 thousand eggs against 2.0 thousand eggs in the infested perch specimesn was found in Chorne Velyke lake. In non-infested individuals of 5-year perch, the highest IAF index was 9.4 thousand eggs when compared to 6.8 thousand in the infested perch (Pulemetske lake). The lowest IAF was 6.3 thousand eggs (Chorne Velyke lake). The highest IAF was recorded in perch from Pulemetske lake (34.6 thousand eggs in non-infested versus 10.3 thousand eggs in infested specimens). The lowest IAF was observed in perch from Chorne Velyke lake (9.1 and 6.6 thousand eggs, respectively). There was decrease in fish size, weight and fecundity in perch infested with Tr. nodulosus, but it did not affect the reproductive fish ability.

ПАРАЗИТОЦЕНОЗ СУДАКА (Sander lucioperca) КУРШСКОГО ЗАЛИВА

Паразитофауна судака водоемов Калининградской области изучалась фрагментарно, и данные о ней носят устаревший характер. Для оценки ихтиопатологического состояния рыбы необходим постоянный мониторинг изменений в составе паразитофауны и показателей зараженности. Проведены четырехлетние исследования паразитофауны судака, обитающего в российской части Куршского залива (Балтийское море). У судака обнаружено 18 видов паразитических орга-низмов: миксоспоридии Myxobolus dispar; микроспоридии Glugea luciopercae; моногенеи Ancyrocephalus paradoxus; цестоды Triaenophorus nodulosus, Diphyllo-bothrium latum; трематоды Bunocotyle cingulate, Diplostomum spathaceum, Tylodel-phys clavata, Bunodera luciopercae, Azygia lucii, Ichthyocotylurus platycephalus, I. variegatus, Bucephalus polymorphus; нематоды Raphidascaris acus, Camallanus lacustris; скребни Acanthocephalus lucii, Corynosoma strumosum; паразитические ракообразные Achtheres percarum. Полный паразитологический анализ проводился по методике, разработанной И. Е. Быховской-Павловской. В паразитоценозе судака преобладают паразиты со сложным жизненным циклом (со сменой промежуточных хозяев). Так, в 2016 г. их доля составила 76,5 % (13 видов); 2017 – 73,4 (11); 2018 –71,4 (10); 2019 – 73,4% (11 видов), тогда как с прямым циклом развития в 2016 г. было 23,5%; 2017 – 26,6; 2018 – 28,6; 2019 – 26,6% (по четыре вида в каждом исследуемом году) паразитов. Повышение зараженности судака трематодами может указывать на процессы эвтрофикации в водоеме. За четыре года исследований наблюдались значительные различия в составе паразитофауны и экстенсивности заражения отдельных видов паразитических организмов. Ос-новной путь заражения паразитами со сложным циклом развития – трофический. Представители класса трематод доминируют в паразитофауне судака Куршского залива (восемь видов). Наибольшая экстенсивность инвазии зарегистрирована у моногенеи Ancyrocephalus paradoxus (100% в 2019 г.), метацеркария трематоды Ichthyocotylurus platycephalus (100% в 2019 г.) и паразитического ракообразного Achtheres percarum (100% в 2016-2019 гг.).

PIKE’S (ESOX LUCIUS) PARASITOPHAUNA OF THE RIVER VYATKA

This study aims to study the pike (Esox lucius) parasitic fauna in the Vyatka River of the Kirov region. Studies were conducted at two sites in the middle of the river Vyatka in 2016–2018 The distance between them is 300 km. A total of 26 individuals were investigated. Caught specimens of fish were examined for the presence of parasites in accordance with generally accepted methods. Over the entire period of studying the pike parasite fauna in the Vyatka River, 24 different parasite species were recorded by various researchers. As a result of our research, 9 species of parasites were recorded, trematodes – 1 species – Azygia lucii, cestodes – 1 species - Triaenophorus nodulosus, nematodes – 2 species – Сamallanus lacustris, Raphidascaris acus, proboscis worm – 3 species – Acanthocephalus anguillae, Acanthocephalus lucii, Neoechinorhynchus rutili, crustaceans 1 species – Ergasilus sieboldi and glochidia 1 species – Anodonta cygnea. The total infection of pike with all kinds of parasites was 100%, with intestinal species – 66.6%. The high extensiveness of invasion is marked by crustaceans Ergasilus sieboldi – 73.1%. The study provides a comparative analysis of the parasite fauna of the common pike in the Vyatka River over 80 years. There is a tendency to reduce the species diversity of pike parasites from 24 species to 9, the disappearance of some species and the acquisition of new ones – proboscis worm Acanthocephalus anguillae with extensiveness of invasion – 15.4%, intensity of invasion – 5.3 specimen, abundance index – 0.81 specimen. The results obtained allow us to conclude that there is a significant decrease in the species diversity of pike parasites, which is probably due to the influence of the anthropogenic factor.