Published online by Cambridge University Press: 09 August 2011
Diel dissolved oxygen (DO) measurements can be used to estimate water metabolism of aquatic systems, in particular, lakes, lagoons and streams in terms of gross primary production (GPP), ecosystem respiration (Reco) and net ecosystem production (NEP). One of the main assumptions in the calculation of lake metabolism is that Reco is the same for daytime (Rdaytime) and nighttime (Rdarkhr). This study aimed at testing the equal Rdaytime and Rdarkhr assumption to estimate GPP, Reco and NEP in a littoral zone of a temperate shallow lake (Lake Yeniçağa) in northwestern Turkey with and without the assumption. Based on the equal Rdarkhr and Rdaytime assumption, values calculated for GPP and Rdaytime were different than those based on the different Rdarkhr and Rdaytime assumption (P<0.001). GPP was lower by 7.5% in July, 49.6% in September and 14.9% in October, while Reco was lower by 5.9% in July and 55.8% in September. GPP was higher by 8.9% in August and 55% in November, while Reco was higher by 7.8% in August and 23.9% in November.