|
|
Biodiversity of chironomid fauna in mountain lakes and streams influenced by acidification and recovery from acidification.
Černocká, Veronika ; Stuchlík, Evžen (advisor) ; Frouz, Jan (referee)
This thesis examines the influence of acidification on the largest group of macroinvertebrates in mountain lakes and running waters - chironomids. The diversity of chironomids has been associated with temperature, the concentration of dissolved oxygen in the water, the amount of nutrients, and also with the ability to survive in conditions (e.g. extreme pH) that are not suitable for other taxa. Because of this the family Chironomidae has become a dominant group of macrozoobentos in many assemblages affected by acidification. The Bohemian Forest lakes and the Tatra Mountain lakes belong to the most frequently studied locations, which were affected by acidification. The peak of acidification was in the 1980s. It turned out that, during the acidification, the number of chironomids changed and also the species composition of their assemblages. The main reason was a change of trophic status, which chironomids reflected more than a change of pH. A decrease in the number of species occurred after the pH dropped below 5. Until then, only their relative abundance had been affected. Chironomids are also influenced by the toxic effect of Al. The most important factor affecting chironomids fauna is not the value of pH, but the change of food supply. Acid stream food webs are often viewed as being...
|
|
|
Seasonal development, long-term changes and effect of extreme events on macrozoobenthos of acidified brooks in headwater catchments of Litavka, the Brdy Mountains
Beneš, Filip ; Tátosová, Jolana (advisor) ; Peltanová, Jana (referee)
This Master thesis was focused on seasonal development of macrozoobenthos for season 2009-2010, its long-term changes and effects of extreme events on acidified brooks in headwater catchments of the Litavka river in the Brdy Mountains (the Czech Republic). The extreme events are considered: drought, floods and deforestation. Changes in composition of macrozoobenthos were compared with the previous research, which was provided there for season 1999-2000. Headwater catchment of the Litavka river consist of two streams: strongly acidified Litavka-krmelec (LK) and slightly acidified Litavka-hlavní (LH), which is taken as a reference stream. Measured pH levels of LK were in range of 4,00-4,22 (with median 4,10) and concentration of reactive aluminium (R-Al) were in range of 1381-2187 µg.L-1 (with median 1692 µg.L-1 ). Measured pH levels of LH were in range of 4,74-6,22 (with median 5,62) and concentration of reactive aluminium (R-Al) were in range of 8-400 µg.L-1 (with median 33 µg.L-1 ). Concentrations of R-Al are observed due to toxic forms of Al3+ ions on aquatic organisms. The significant differences in composition of macrozoobenthos were also observed. On strongly acidified study site LK were not present acidosensitive groups, such as mayflies, molluscs and some species of caddisflies. All of these...
|
guest ::
