Naslov
The influence of extreme floods from the River Danube in 2006 on phytoplankton communities in a floodplain lake : Shift to a clear state

Autori
Mihaljević, Melita ; Špoljarić, Dubravka ; Stević, Filip ; Cvijanović, Vanda ; Hackenberger Kutuzović Branimir

Izvornik
Limnologica (0075-9511) 40 (2010); 260-268

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Danubian floodplain; Shallow lake; Phytoplankton assemblages; Vertical distribution; Disturbed environment; State shift; Clear state

Sažetak
The influence of extreme floods from the River Danube in 2006 on the species composition and vertical distributions of phytoplankton was studied in a shallow floodplain lake, Lake Sakadaš (Kopački Rit Nature Park, Croatia) which in the last few decades was in a turbid state characterised by high phytoplankton concentrations. As a consequence of extremely high floods, the whole floodplain area (approximately 16 km2) became one lentic habitat with well developed macrophyte vegetation. Seasonal dynamics of chlorophyll a (Chl a) concentration in the lake had a characteristic pattern for the shallow lakes with dense macrophyte vegetation. Extremely low mean phytoplankton abundance and biomass were found in the conditions of very high nutrient concentrations. Dominant phytoplankton species were diatoms (species from the functional groups B, C, D and P) and chlorococcal green algae (species from the functional groups F, G, J, X1 and X3). The canonical correspondence analysis (CCA) demonstrated that nutrients and temperature were significant environmental variables for their development. The sequence of phytoplankton seasonality (summarized as B/C/D – X1/J/T/F/(P) – X1/F/(B/C) – B/C), vertical distribution of phytoplankton, as well as the domination of rapidly acclimating phytoplankton forms (R-strategists) indicated a clear, well-mixed conditions and a highly disturbed environment. Our results suggest that the occurrence of extreme flooding can be a stressor high enough for the transition from a turbid to a clear state of the floodplain lake. Possibly, cyclic shifts between alternative stable states in floodplain ecosystems can be expected as a consequence of the impact of extreme hydrological events induced by a climate change.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

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