Search

Eutrophication impact on key aquatic communities (phytoplankton, macrophytes and macrozoobenthos) was studied in three standing water bodies in Bulgaria (Kardzhali, Koprinka and Batak). The reservoirs had a high summer nutrient level and were between eu- and hypertrophic category. In the meso-eutrophic condition the highest number of phytoplankton species and functional diversity (Kardzhali Reservoir) and domination of functional groups (FGs) B, F, X3 and T were registered. The most intensive cyanobacterial growth was recorded in eu- to hypertrophic conditions (Koprinka Reservoir), as well as lower functional and species diversity, and domination of FGs M and J. Hydrological regime in hydroelectric reservoirs was a serious pressure for aquatic macrophytes and macrozoobenthos. Along the nutrient gradient, the Batak Reservoir had highest phytoplankton biovolume and macroinvertebrate taxa richness, well developed macrophyte community, dominated by eutrophication-tolerant species. The results suggested that measures for mitigating ecological impacts from pressures should be implemented without significant adverse effect on water use. [ABSTRACT FROM AUTHOR]

The current status of a lake can be evaluated via monitoring based on biological quality elements. Reference aquatic flora communities reflect pristine situations that exist or would exist with no or very minor disturbances from anthropogenic pressure. Phytoplankton and macrophytes were studied in 10 national lake types (L1, L3, L4, L5, L7, L8, L11, L12, L13, L17). Type-specific taxa and groups character in reference and near reference conditions were described. Abiotic parameters (water chemistry) were also discussed. Descriptor species from 25 FGs were registered in phytoplankton communities in lakes in reference and near reference conditions. Dinoflagellates (L0) cryptomonads (Y) and various benthic/periphytic taxa (MP) were distributed in almost all lake types. Character descriptor species and FGs were reported for lake types L1 and L5. Motile mixotrophic dinoflagellates (L0) and cryptomonads (Y) had highest relative biovolume in ultraoligotrophic alpine lakes (L1) due to their ability to utilize effectively scarce trophic resources. Motile euglenoids (W1, W2), small-celled colonial Cyanobacteria (K), green algae and small cryptomonads (X1, X2), coccal green algae (J) and meroplanctonic diatoms (MP) dominated phytoplankton community in riverine marshes (L5). Recorded FGs from natural lakes were also common in and their analog among heavy modified water bodies: shallow lowland reservoirs L17. Phytoplankton communities of L13 (small and medium-size semi-mountain reservoirs in the Eastern Balkans) were more similar with those of L11 (large deep reservoirs) and mountain L1, L3. Further surveys are needed in order to classify specific features of phytoplankton communities in L3, L4, L7, L11 and L12. [ABSTRACT FROM AUTHOR]

Cyanobacteria are photosynthetic prokaryotes with cosmopolitan distribution. They are major producers of primary biomass and free oxygen in most of the freshwater and marine biomes on the planet. Under certain conditions of the environment, these organisms can evolve massively and cause the so-called "water blooms". Very often these blooms are toxic due to the ability of some cyanobacteria to produce dangerous toxins (cyanotoxins) with hepatotoxic, neurotoxic or dermatotoxic effects. This determines the cyanobacteria as an ecological risk for the aquatic ecosystems as well as a threat for the health of animals and humans. Climate changes also lead to an increase in the percentage of cyanobacterial blooms. Therefore, the investigation of the species composition of this group in the Bulgarian reservoirs, the tracking of the blooms frequencies as well as the assessment of their toxic potential is of great importance. Unfortunately, such data at this stage are scarce. This study presents data on the species composition and toxic potential of Cyanobacteria during the summer months of 2017 in five reservoirs (Batak, Dospat, Shiroka polyana, Golyam Beglik and Krichim dams) in the Western Rhodope Mountain. During the investigation period, except the representatives of Cyanobacteria, seven algal phyla (Chlorophyta, Bacillariophyta, Euglenophyta, Dinoflagellata, Cryptophyta, Chrysophyta and Xantophyta) were also found in the dams. The frequency and percentage of cyanobacteria were reported. A taxonomic list of the determined cyanobacterial species is given for each water body. In addition, a quantitative characteristic for each species (density and biomass) was performed. By using ELISA tests for cyanotoxins we have analyzed the presence of microcystins/nodularins (MCs/Nod) and saxitoxins (STXs). Cyanotoxins were found in four of the studied water basins - Dospat Dam, Batak Dam, Shiroka polyana Dam and Krichim Dam. [ABSTRACT FROM AUTHOR]

This study reports data on the diversity of bryophytes in the Bulgarka Nature Park. The registered 55 species belonged to 23 families and 46 genera. Six species were with conservation status; 2 were assessed as Not Evaluated. The main threats were assessed and measures towards bryophyte conservation were proposed. [ABSTRACT FROM AUTHOR]

The object of investigation is the region of peak Malusha, Kozyata Reka river and the adjacent territories. The studied area is located in the main watershed ridge of the Shipka divide of Central Balkan Range. Identified are 621 species of vascular plants belonging to 355 genera and 88 families. A description of the floristic composition is made. Attached is the so far compiled list of the identified plant species. A table is offered with the important plant species that occur within the mountain massif. Identified are 23 plant species with international protection status, subject to conservation in the Protected Zone Balgarka BG0000399 and Protected Zone Central Balkan - buffer BG0001493. [ABSTRACT FROM AUTHOR]