Naslov
Bioassay in Eutrophication Monitoring of Lake Sakadaš (Nature Park Kopački Rit)

Autori
Horvatić, Janja ; Mihaljević, Melita

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Shallow lakes 2002-Abstracts / Judit Padisak - Balatonfuered : Veszprem University Press, 2002

Skup
International Conference on Limnology of Shallow Lakes

Mjesto i datum
Balatonfüred, Mađarska, 25.05.2002. - 30.05.2002

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
algal growth potential (AGP); Chlorella kessleri; nitrates; phosphates; microphytoplankton biomass

Sažetak
Comparative evaluation of the trophic state of Lake Sakadaš, the deepest lake in the wetland ecosystem of the Nature Park Kopački Rit, was done using the miniaturized bioassay method, as well as according to physical and chemical water parameters and seasonal succesions of phytoplankton. Sampling was done at monthly intervals from March till Dec. of 1999. The algal growth potential (AGP) of culture Chlorella kessleri FOTT et NOV. was investigated. AGP in original water samples from Lake Sakadaš and the influence on the AGP due to adding nitrates (final conc. of 0.180 ; 0.360 ; 0.723 g l-1) and phosphates (final conc.of 0.028 ; 0.056 ; 0.169 g l-1) were determined. Water dynamics is the main ecological factor in the Lake Sakadaš. According to dynamics of flooding, during 1999 two periods can be distinguished: inflow of water to the wetland from the Danube with a high water level (March-July) and outflow of water from the lake to the Danube with decreasing of water level (August- December). High Secchi depth (1.1-3.6 m), low amount of phytoplankton (2.43-45.02 &#956 ; ; g l-1 chl-a) with predominance of Dinobryon and diatoms (Asterionella, Melosira) was the characteristic of the period of low water level and indicated oligo-mezotrophic and low eutrophic conditions. Results of AGP based on the maximal biomass of C. kessleri in original water samples (32-63 mgl-1DW) proved the oligotrophic till mesoeutrophic conditions. Results of AGP in conditions of increasing phosphates (all three conc. stimulated the growth of C. kessleri) proved the low level of phosphates in Lake Sakadaš. The algal blooms of Peridinium and Euglenophyceae (69.88 - 86.85 &#956 ; ; g l-1 chl-a) and low Secchi depth (0.59-1.03 m) was the main characteristic of the eutrophic conditions in the period of low water level. Results of AGP based on the maximal biomass of C. kessleri (till 92 mgl-1 DW) in original water samples proved the mezo-eutrophic conditions while AGP was unchanged in conditions with increasing of phosphates. According to statistical analysis it can be concluded that phosphates were not a limiting factor of C. kessleri growth. Based on the AGP results in conditions of increasing nitrates, there is an evident increase in the C. kessleri growth. It can be concluded that nitrates controlled the eutrophication of Lake Sakadaš during the whole investigation period. Regarding the given results, the method of bioassay will be introduced and tested in the long-term period for the monitoring of eutrophication of Lake Sakadaš.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

POVEZANOST RADA