Keywords

lake metabolism, primary production, carbon, nitrogen, phosphorus, phytoplankton, bacteria, carbon balance

Disciplines

Life Sciences

Abstract

During 2009 and 2010, we quantified monthly changes in plankton metabolism and environmental variables in the surface waters of Muskegon Lake, a Great Lakes estuary connected to Lake Michigan. Muskegon Lake’s mean (±SE) annual gross plankton primary production (GPP) and respiration (R) rates were 46 ± 9 and 23 ± 4 mg C l−1 yr−1, respectively. GPP:R ratios of 0.6 to +4.8 with a yearly mean of 2.0 ± 0.3 indicated that the surface water of Muskegon Lake was net autotrophic during all but the winter months under ice cover, when it was in a near carbon balance to slightly heterotrophic state. Approximately 5% of GPP and 12% of R occurred during the winter months, highlighting winter’s potential role in nutrient regeneration. An overall positive annual net community production (NCP) rate of 28 ± 6 mg C l−1 yr−1 makes Muskegon Lake’s surface waters a net sink for carbon on an annual basis. Annual heterotrophic bacterial production (BP) rates were 5 ± 3 mg C l−1 yr−1, suggesting a substantial fraction of GPP was likely processed through the microbial food web (2 to 76%). A stepwise multiple linear regression model revealed the plausible drivers of GPP (temperature [T], photosynthetically active radiation [PAR], total phosphorus [TP], dissolved oxygen [DO], chlorophyll a [chl a]), NCP (T, PAR, TP), R (T, DO, ammonium [NH3], soluble reactive phosphorous [SRP], dissolved organic carbon [DOC]) and GPP:R (T, PAR, SRP, DOC). Year-round measurements inform us of the strong seasonality in the carbon cycle of temperate lakes.

Original Citation

Defore, A. L., Weinke, A. D., Lindback, M. M., & Biddanda, B. A. (2016). Year-round measures of planktonic metabolism reveal net autotrophy in surface waters of a Great Lakes estuary. Aquatic Microbial Ecology, 77(3), 139–153. https://doi.org/10.3354/ame01790

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