The purpose of this review is to describe the contents of Pb and Zn in sediments and hydrobionts as ecological markers for the pollution assessment of freshwater objects in Bulgaria, and the data are compared with other countries and regions. Symmetry was found regarding the levels of Zn in the sediment of the Ovcharitsa and Zhrebchevo dams, which were twice the MAC for arable land (Regulation № 3 of Bulgarian legislation). Symmetry was also observed between the results for Zn and Pb in the studied sediments, and the “favorites” in terms of content were the samples from Zhrebchevo Dam and, especially, from Ovcharitsa Dam. Asymmetry was established in the accumulation of Zn in the livers of carps inhabiting Topolnitsa Dam in comparison with these in Ovcharitsa Dam. A similar asymmetry was observed for lead. The analysis of the muscles and livers of the studied fish showed an asymmetry in the accumulation of zinc, and this process was more intense in the liver. Symmetry was found in the accumulation of Pb in the liver and muscle tissues of the carp from the studied water bodies.

Diorchis thracica n. sp. (Cestoda, Cyclophyllidea, Hymenolepididae) is described from the ruddy shelduck Tadorna ferruginea (Pallas) (Aves, Anseriformes, Anatidae), collected in the vicinities of Radnevo, Stara Zagora Region, Bulgaria. The new species is differentiated from other members of Diorchis Clerc, 1903 by possessing rostellar hooks with length of 36 µm, a thick-walled cirrus-sac with strong longitudinal muscular fibres in its middle part and a copulatory vagina with two sphincters. Main morphological criteria for distinguishing species of the genus Diorchis are discussed.

The aim of the present review is to summarise the information about the species diversity of wild and synanthropic birds, which have been recorded as reservoirs of influenza in Bulgaria until 2018. A total of 17 species of wild and synantropic birds were reported. They belong to 16 genera, 11 families and 10 orders of the class Aves. A list of wild and synantropic birds – potential reservoirs of influenza in Bulgaria is also presented.

No abstract