New records of trematode and acanthocephalan species in frogs in Erzurum Province, Turkey

Summary A total of 32 frogs of two species (Rana macrocnemis, Pelophylax ridibundus) that were dissected in some lectures in Ataturk University Science Faculty Biology Department were investigated parasitologically even after the lectures between 2008 and 2014. 9 digenean species (Cephalogonimus retusus [Cephalogonimidae]; Diplodiscus subclavatus [Paramphistomotidae]; Gorgodera cygnoides, Gorgoderina vitelliloba [Gorgoderidae]; Haplometra cylindracea, Haematoloechus variegatus, Opisthioglyphe ranae, Skrjabinoeces similis and Skrjabinoeces breviansa [Plagiorchiidae]), 3 acanthocephalan species (Acanthocephalus ranae, Centrorhynchus sp., Pomphorhynchus laevis) were found. All the parasites are the first record for Erzurum province, Cephalogonimus retusus and Skrjabinoeces similis are the first records of the parasite fauna of Turkey.

Distribution of Pomphorhynchus laevis s.l. (Acanthocephala) among fish species at a local scale: importance of fish biomass density

Parasite distribution among hosts is a fundamental aspect of host–parasite interactions. Aggregated parasite distributions within and across host species are commonly reported and potentially influenced by many factors, whether host or parasite specific, or related to host–parasite encounter and compatibility. Yet, the respective role of each in observed parasite distributions are often unclear. Here, we documented the distribution of the acanthocephalan parasite Pomphorhynchus laevis sensu lato (s.l.) in two replicate fish host populations. Aggregated distributions were observed in both populations, within and across fish host species. We found a positive abundance–prevalence relationship across fish species, suggesting that resource availability (fish host biomass density) was the main driver of P. laevis s.l. distribution. This was supported by further positive associations between mean parasite load and fish biomass density. We found little evidence for intensity-dependent regulation within host (i.e. intra-host competition among co-infecting parasites). Furthermore, P. laevis s.l. infection had no detectable effect on fish condition indices, except on the body condition of female barbel (Barbus barbus). Therefore, P. laevis s.l. tended to accumulate with size/age within fish species, and with fish biomass density among fish species, with apparently negligible limitations due to intra-host intensity-dependent regulation of parasite, or to parasite-induced morbidity in fish. The relative availability of final hosts for trophic transmission thus appears to be the main driver of P. laevis s.l. distribution among fish.

New data on endohelminth communities of barbel Barbus barbus from the Bulgarian part of the River Danube

Summary Species diversity and composition of the parasite communities of barbel (Barbus barbus) at the infracommunity and component community levels were studied in the Lower Danube River, Bulgaria. During the two-year investigations, five parasite species have been found in 92 host fish: Bathybothrium rectangulum (Cestoda), Acanthocephalus anguillae and Pomphorhynchus laevis (Acanthocephala) and larval stages of Contracaecum sp. and Raphidascaris acus (Nematoda). Bathybothrium rectangulum and R. acus found in barbel represented new host records in Bulgaria. Parasite communities of barbel were species-poor and highly unbalanced. Pomphorhynchus laevis represented the dominant (core) species (prevalence 98.9 %), the second most frequent component parasite was Contracaecum sp. (P = 14.1 %) and remaining three species occurred only accidentally in barbels. Differences in species richness, prevalence, intensity of infection and ecological indices between individual seasons (spring, summer, autumn) were statistically significant, but considerably affected by unequal species structure of communities with highly prevailing P. laevis. Low parasite species diversity of barbel and low values of most ecological indices, when compared with previous studies in this area (or other Bulgarian parts of the River Danube) might indicate that environmental conditions are impaired and thus, not favourable for the development of barbel parasites (primarily to their intermediate host survival) in the Lower Danube River of Bulgaria.

Parasitofauna of the Caspian salmon (Salmo trutta caspius Kessler) at the salmon fish hatcheries of Azerbaijan for the period of their existence

The Caspian salmon is included in the Red List of Azerbaijan with the international status CR (Critically Endangered). The article presents the comparative analysis of the parasitofauna of the Caspian salmon (Salmo trutta caspius Kessler) during the period of its existence (1955–2015) at the hatcheries of Azerbaijan (Chaykend and Chukhur-Gabala salmon fish hatcheries). When comparing the quantitative index of parasitofauna for the first years after the creation of the salmon fish hatcheries (9 species of parasites) and studies carried out by the authors (7 species of parasites), it was revealed that the change was insignificant. However, significant changes in the species composition of the parasitofauna of the Caspian salmon were found. The parasites Chilodonella piscicola, Trichodina truttae, Eubothrium crassum, Rhabdochona gnedini, Cystidicoloides tenuissima, Piscicola geometra found in the first years of the salmon fish hatcheries were not recorded by the authors, and Bunodera luciopercae, Metechinorhynchus baeri, Pomphorhynchus laevis, Glochidium sp. revealed in recent studies were not observed in the early years. The dominant groups of parasites of the Caspian salmon were revealed. A systematic review of all parasites of salmonids found during this period is presented. Three species of parasites were noted for the first time in the territory of Azerbaijan for the Caspian salmon in the salmon fish hatcheries (trematode Bunodera luciopercae, acanthochephala Pomphorhynchus laevis and mollusk Glochidium sp.). The authors specifically noted parasites identified from 2005 to 2015 that are conditionally pathogenic for the Caspian salmon and capable to cause significant damage to the salmon hatcheries: Costia necatrix, Ichthyophthyrius multifiliis, Gyrodactylus derjavini, Metechinorhynchus baeri, Pomphorhynchus leavis, Bunodera luciopercae. The authors note that during the period of parasitological studies of the Caspian salmon in salmon hatcheries in Azerbaijan, pathogenic parasites for humans have not been found.