Limnological characteristics of a Danube oxbow-lake (Danube-Dráva National Park, Hungary)
Ágoston-Szabó, Edit; Schölldinka, Károly; Dinka, Mária
Spatial and temporal changes in the water chemical parameters and chlorophyll-a concentration were investigated in Külső-Béda oxbow-lake of the Danube and compared with that of the main channel in 2007-2008. The oxbow-lake water differed from that of the main arm with regards to concentrations of the C, N and P forms. The NO3--N, PO43--P, TDN, TDP concentrations were remarkably lower, while the concentrations of DOC, TDC, TOC and of chlorophyll-a were higher in the oxbow-lake than in the main channel. The differences between the NO3--N and PO43--P concentrations of the main arm and oxbow-lake decreased with increasing river discharge. The phytoplankton biomass significantly correlated with the TP (r=0.90), NO3--N (r=-0.45) concentrations and TDN:TDP ratio (r=-0.47), NO3--N:PO43--P ratio (r=-0.55), which suggested P limitation of phytoplankton growth. Significant positive correlation was found between the chlorophyll-a and SPM, POC. The phytoplankton biomass negatively, while NO3--N concentration positively correlated with the water discharge of the main arm. The limnological characteristics of BDU were dependent on the water regime of the main channel.