2023 Volume 46 Issue 5 Pages 149-155
Gross primary production (GPP) and ecosystem respiration (ER) , as well as chlorophyll a (Chl a) and nutrient concentrations, were measured in the central part of Lake Teganuma in both 2018 and 2021. The autotrophic and heterotrophic communities showed high activity levels during summer and fall, which were strongly affected by water temperature. Net ecosystem production (NEP = GPP − ER) was positive throughout the study period, with an average GPP/ER ratio of 4.0. The mean GPP value (9.4 mgO2 L−1 d−1) was approximately six times higher than the threshold GPP (GPP at GPP = ER: 1.6 mgO2 L−1 d−1) . Therefore, the central part of Lake Teganuma was autotrophic. The variations in GPP and NEP were closely related to changes in Chl a concentration, which explains approximately 40% of the variance in GPP and NEP.
