Original paper

Limnological characteristics of a Danube oxbow-lake (Danube-Dráva National Park, Hungary)

Ágoston-Szabó, Edit; Schölldinka, Károly; Dinka, Mária

Abstract

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.

Keywords

chemical parameterslarge riverfloodplainwater level