| Author/Editor | Ognjanova-Rumenova, Nadja; Botev, Ivan; Velle, Gaute; Brancelj, Anton | |
| Title | Environmental changes in the Rila mountains, southwestern Bilgaria, as recorded by the sediments of a remote lake | |
| Type | članek | |
| Source | In: Catalan J, Curtis CJ, Kernan M, editors. Patterns and factors of biota distribution in remote European lakes. Stuttgart: Schweizerbart science publishers, | |
| Publication year | 2010 | |
| Volume | str. 295-318 | |
| Language | eng | |
| Abstract | Chemical and biological sedimentary records of the high alpine lake Bubreka, RUa Mountains, Bulgaria, were used to reconstruct palaeoecological conditions and to determine the phases in the ontogeny of the lake. Sediment cores taken in 2000 were dated by 210Pb and 137Cs and analysed for percentage of dry weight (%DW), loss-on-ignition (LOI), pigrnents, diatoms, chrysophyte stomatocysts, cladocerans, chironomids and spheroidal carbonaceous particles (SCPs). The studies on Lake Bubreka show that high mountain lakes are good sites for the study of the evolution and effects of the long range transport of atmospheric pollutants from the industriallow1ands to mountain regions. Four distinct successional phases can be described in the lake history during the last - 250 years, revealing comp lex interactions between anthropogenic impact and climate. Phase 1 (ca. AD 1762-1834) is characterised by stable oligotrophical conditions. During Phase 2 (ca. AD 1834 -1928) there is a change from oligotrophic to mesotrophic conditions. Phase 3 (ca. AD 1928 - 1994 ± 2) shows an increase in LO! due to the high proportion of organic material. The shorter ice cover period in the lake may have created conditions more suitable for the growth of phyto- and zooplankton and changed the overall primary production from benthos to plankton. In Phase 4 (ca. AD 1994 ± 2 - 2000) there is increased LO!, increasing percentages of periphytic diatoms, less favorable conditions for cladocerans, and rheophilic chironomid assemblages which indicate rapid input of nutrients causing mesotrophication. The SCP record and comparisons with other European mountain lakes suggest there is a mode rate impact from atmospheric deposition compared with similar lakes elsewhere in Europe. | |
| Descriptors | ECOSYSTEM FRESH WATER GEOLOGIC SEDIMENTS DIATOMS CHIRONOMIDAE CRUSTACEA CHLOROPHYLL CAROTENOIDS CARBON NITROGEN SULFUR BULGARIA |