Checklist of the parasites of European eel Anguilla anguilla (Linnaeus, 1758) (Anguillidae) in Poland

The present paper lists all parasite species of the European eel Anguilla anguilla (Linnaeus, 1758), recorded in Poland, in both its saltwater and freshwater habitats. The list has been drawn up, based on data acquired since 1844. The majority of included parasite species are presented with fish infection parameters together with data on their developmental stages and occupied microhabitats, localities and dates of collection of the eels themselves. The database includes 62 parasite taxa (including 50 species, nine identified to the genus level and three to higher taxa), representing at least 47 genera and 39 families. The most frequently-noted parasites of the European eel are the cestode Bothriocephalus claviceps, the nematodes Anguillicoloides crassus, Camallanus lacustris and Raphidascaris acus and the acanthocephalan Acanthocephalus lucii. Four alien species have been noted from this host: A. crassus, the monogeneans Pseudodactylogyrus anguillae and Pseudodactylogyrus bini and the acanthocephalan Paratenuisentis ambiguus. The present list includes both new host records and earlier records not included in previous lists of parasites of eels.

Metazoic parasites of Siberian roach Rutilus rutilus lacustris (Pallas) in the Tobol river

The article describes the problems of the Ob-Irtysh basin (the Tyumen region), which is a natural focus of opisthorchosis. Localized in the bile ducts of the liver, the pathogen of opisthorchosis poses a risk to the human body. Parasitic community of Siberian roach inhabiting the Tobol Riverwas studied in the autumn period of its life cycle. There were examined 24 fish species of different sexes at the age of 0+ to 4+. There was registered the roach invasion by 9 species of para-sites belonging to 6 systematic groups: Monogenea - 2, Cestoda - 1, Trematoda - 4, Nematoda - 1, Bivalvia - 1, Copepoda - 1. Parasitization of gills by monogeny Dactylogyrus crucifer with inva-sive extensiveness of 83.3% and Paradiplozoon homoion homoion with invasive extensiveness of 16.7% has been stated. Diplostomum chromatophorum parasitizes in the lens of the eye, in total 18 of the examined fish are invaded. Opisthorchis felineus was found in muscles with invasive exten-siveness of 29.2%. Immature specimens of Sphaerostoma bramae were found in the intestines of nine fish examined. Mesentery of 4 fish species and liver of 1fish species examined are affected by Raphidascaris acus at a larval stage. The dominant parasite in the study is Rhipidocotyle campanula. Trematode at the metacercaria stage was found on the gills and fins, the overall infection rate comes to 70.8%. Also, Ergasilus sieboldi parasitizes on the gills and fins of the examined roach species. Depletion of the species composition of parasites is observed in the autumn period of the roach life cycle.

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.

Parasites of the spiny loach Cobitis taenia Linnaeus, 1758 (Pisces: Cobitidae) from Saratov Reservoir

Objective of research. To study the species composition of the parasite fauna and the infestation rate of the spiny loach Cobitis taenia Linnaeus, 1758 from Saratov Reservoir. Materials and methods. The material was collected in the Mordovo-Kol’tsovsky area of the Reservoir (the middle part of the reservoir) in 2009 and 2014–2015. Fishing was carried out by a hydrobiological net. Totally 47 individuals of spiny loach were investigated by the method of full parasitological autopsy. Collection, fixation and office studies were carried out using the standard technique; diagnostics of species composition of parasites — by identification guides. To estimate the rate of fish invasion, we used the common parasitological indices: extensity of invasion, intensity of invasion and the index of abundance of parasites. Results and discussion. 7 species of parasites belonging to 5 classes: Monogenea — 1, Cestoda — 1, Trematoda — 3, Nematoda — 1, Bivalvia — 1 were found in the spiny loach Cobitis taenia Linnaeus from Saratov Reservoir. The species composition of parasites and the level of host infestation directly depend on the lifestyle and nutrition of fishes. Eating the infected benthic and weed bed invertebrates (oligochaetes, larvae and adult insects), the spiny loach becomes infected with 3 species of helminths. 4 species of parasites infect the host using the active infestation way. Most of the parasites found in fish from different families and groups are wide specific. The parasite fauna includes 1 species, narrow specific for the spiny loach (monogenea Gyrodactylus latus Bychowsky, 1933) and 1 species specific for loaches (fam. Cobitidae) — metacercariae of Holostephanus cobitis Opravilova, 1968. For 4 species of parasites, the spiny loach is the final (definitive) host, for 3 — intermediate. The dominant species in the composition of the parasite fauna C. taenia is the trematode H. cobitidis (mtc.); the extensity of infection with it reaches 97,9%, the abundance index is 10,8 ind. Fluke larvae infect fishes (using the active way) penetrating through the skin. The most pathogenic for spiny loach parasites are the monogenea G. latus, metacercariae of trematodes H. cobitidis and Paracoenogonimus ovatus Katsurada, 1914, the larva of the nematode Raphidascaris acus Bloch, 1779.

Do eel parasites reflect the local crustacean community? A case study from the Rhine river system

In 2003, the parasite fauna of 197 European eelsAnguilla anguilla, captured at three different locations (Laufenburg, Karlsruhe and Beneeden Leeuwen) in the River Rhine, was analysed. The eels harboured a total of 18 species, among them the protozoa (Myxidium giardi, Myxobolus kotlaniandTrypanosoma granulosum), acanthocephalans (Acanthocephalus anguillae, Acanthocephalus lucii, Echinorhynchus truttae, Pomphorhynchus laevis), nematodes (Paraquimperia tenerrima, Pseudocapillaria tomentosa, Camallanus lacustris, Raphidascaris acus, Spinitectus inermisandAnguillicola crassus), cestodes (Bothriocephalus clavicepsandProteocephalus macrocephalus) and monogeneans (Pseudodactylogyrussp.). The parasite fauna at the different locations is discussed with respect to the crustacean fauna present at these locations. The investigation shows that changes in the composition of the crustacean fauna, due to the anthropogenic breakdown of a biogeographic barrier, are reflected in the composition of the intestinal eel parasite fauna.