This is the first record of Dyschiriodes (Eudyschirius) gracilis gracilis (O. Heer, 1837) (Coleoptera: Carabidae: Scaritinae) from Bulgaria. It was collected in the Srebarna Reserve in NE Bulgaria ...via light attraction. Considering its current distributional range, we may suggest that D. gracilis gracilis is to be found in Croatia and Romania too.
Black bullhead
Ameiurus melas
(Actinopterygii: Siluriformes) is an alien fish species of North American origin, which has expanded its invasive geographical range in Europe. In 2017–2019, 32 black ...bullhead specimens from the Lake Srebarna Biosphere Reserve, Bulgaria, were examined for monogenean parasites. Two species of monogeneans were recorded and identified on the basis of morphological and molecular data:
Ligictaluridus pricei
(Ancyrocephalidae), with prevalence 100% and intensity 2–32 (mean 13.3 ± 6.8), and
Gyrodactylus nebulosus
(Gyrodactylidae), with prevalence 72.0% and intensity 1–15 (mean 7.4 ± 4.3). Partial 18S rDNA and the ITS1 region of
L. pricei
were sequenced. For
G. nebulosus
, sequenced genes included the partial 18S rDNA and the entire ITS1–5.8S rDNA–ITS2 region as well as the mitochondrial COI gene. Both recorded monogenean species are specific parasites of North American ictalurid fishes and alien to Europe. The present study is the first record of
L. pricei
from Bulgaria and the first record of
G. nebulosus
from Europe and the Palaearctic Region.
We give the results from the first investigation focused on the land snail fauna in Srebarna Nature Reserve in Bulgaria. A total of 23 localities were studied and 27 species of terrestrial gastropods ...were found, 23 of which were new observations for the Reserve.
Altogether 180 specimens of Perca fluviatilis (L.) from Srebarna Lake, North-eastern Bulgaria, were examined for helminths during spring, summer and autumn of 2005 – 2006. Of them, 143 (79.4 %) perch ...were infected with helminths. Thirteen helminth species were found: metacercariae of Bolbophorus confusus, Diplostomum pseudospathaceum, D. spathaceum, Ichthyocotylurus pileatus, Posthodiplostomum cuticola and Tylodelphys clavata; cestode Proteocephalus percae; acantocephalans Acanthocephalus anguillae and A. lucii and nematode larvae Contracaecum microcephalum, Eustrongilides excisus, E. tubifex and Rhaphidascaris acus. The digenean T. clavata was dominant species of the perch component community. Little seasonal differences were found in the prevalence, abundance and mean infection of helminths. Eustrongilides tubifex reported from the territory of Bulgaria for the first time, represent the new geographical records and new species of Bulgarian helminth fauna.P. fluviatilis was reported as a new host record for two digeneans, namely Diplostomum pseuspathaceum and Posthodiplostomum cuticola, the cestode Proteocephalus percae, the acantocephalan Acantocephalus anguillae and the nematodes Contracaecum microcephalum and E. tubifex from the territory of Bulgaria. P. fluviatilis was reported as a new host record for D. pseudospathaceum, P. cuticola, C. microcephalum and E. tubifex from Balkan peninsula.
Results of an analysis of phytoplankton samples, collected between 1982 and 1995 from Srebarna Lake, a biosphere reserve, in north-eastern Bulgaria, are presented. The lake is polymictic, and ...strongly eutrophied. It has undergone an anthropogenically-forced succession. In 1994, a restoration of the lake was commenced when a canal connecting it to the Danube River was built.Special attention is paid to the shifts in the qualitative composition of the phytoplankton (240 species), in the number of dominant species and assemblage structure, as well as to the changes in structural parameters and phytoplankton abundance during lake enrichment. The generalised changes involved a shift from a chlorococcal dominated-phytoplankton, rich in phytoplankton groups, to a chroococcal and oscillatoralean one, poor in algal groups. With recovery, from hypertrophy to eutrophy, more algal groups contributed to the phytoplankton, and dominance of chlorococcal genera resumed. An increase in total phytoplankton abundance with advancing eutrophication and a decrease during early oligotrophication were detected. The values of structural parameters were related to nutrient input and changed after restoration. However, the stages of phytoplankton development along the trophic gradient and back were not exactly reversed.
The results of pollen analysis of two sediment cores from lake Srebarna (northeast Bulgaria) are presented. On the basis of the palynological data and the radiocarbon dates a reconstruction of the ...past flora and vegetation is made. For the first time a continuous palaeosuccession is established for the area of the Danubian Dobrudza and the Ludogorie district of northeast Bulgaria: a dominance of mixed xero- and mesophilous oak woods with Carpinus betulus, Ulmus, Tilia, Corylus during the Atlantic period; mixed oak woods with increasing importance of Tilia, Ulmus, Acer and a considerable presence of Carpinus betulus and Fagus during the Sub-boreal period; degradation of the woodland vegetation and transition to secondary plant communities with Carpinus orientalis and herbs during the Sub-atlantic period.
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