Persistence of net heterotrophy in lakes during nutrient addition and food web manipulations

By J. Cole, Michael M. Pace, Stephen R. Carpenter, J. Kitchell. 2000

502 citations recorded by the source corpus.

Net ecosystem production (NEP) is the difference between gross primary production (GPP) and community respiration (R). We estimated in situ NEP using three independent approaches (net CO2 gas flux, net O2 gas flux, and continuous diel O2 measurements) over a 4–7 yr period in a series of small lakes in which food webs were manipulated and nutrient loadings were experimentally varied. In the absence of manipulation, these lakes were net heterotrophic according to all three approaches. NEP (NEP = GPP‐R) was consistently negative and averaged −35.5 ± 3.7 (standard error) mmol C m−2 d−1. Nutrient enrichment, in the absence of strong planktivory, tended to cause increases in estimates of both GPP and R (estimated from the continuous O2 data) but resulted in little change in the GPP/R ratio, which remained <1, or NEP, which remained negative. When planktivorous fish dominated the food web, large zooplankton were rare and nutrient enrichment produced positive values of NEP by all three methods. Among lakes and years, daily values of NEP ranged from −241 to +175 mmol m−2 d−1; mean seasonal NEP was positive only under a combination of high nutrient loading and a planktivore‐dominated food web. Community R is significantly subsidized by allochthonous sources of organic matter in these lakes. Combining all lakes and years, we estimate that ~26 mmol C m−2 d−1 of allochthonous origin is respired on average. This respiration of allochthonous organic matter represents 13 to 43% of total R, and this fraction declines with increasing GPP.

Subfields: Environmental Chemistry, Nature and Landscape Conservation, Oceanography

View Paper: https://www.semanticscholar.org/paper/6c0f4951b1533b6181b2fd2b556cbda9c60fd2a8

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Citations in the corpus

Pathways of organic carbon utilization in small lakes: Results from a whole‐lake 13C addition and coupled model (2002, methodology): “Electrode drift and exchange with the atmosphere were calculated as in Cole et al. (2000).”
The Temperature Dependence of the Carbon Cycle in Aquatic Ecosystems (2010, background): “…DEPENDENCE OF THE AQUATIC CARBON CYCLE allochthonous carbon subsidies, as is frequently prevalent in freshwater, estuarine and coastal ecosystems (Cole et al. , 2000, 2002; del Giorgio and Peters, 1994; del Giorgio et al. , 1997; Pace et al. , 2004; Ram et al. , 2007), the temperature…”
Derivation of lake mixing and stratification indices from high-resolution lake buoy data (2011, background): “For example, depth of the mixed layer has been calculated as a threshold of turbulence (MacIntyre et al., 2009), a temperature gradient (Coloso et al., 2008), a density gradient (Lamont et al., 2004), or chemical gradient (Cole et al., 2000).”
Trophodynamic indicators for an ecosystem approach to fisheries (2005, unknown): “…experiments, models Used in efficiencies and system indices; accounting for system’s heterotrophy: Td (Christensen and Pauly, 1993; Christensen, 1995; Cole et al., 2000) Throughput e sum of all flows in and out of a group or system/models Index of system size in terms of flow: mostly Bu…”
Bacterial metabolism and growth efficiency in lakes: The importance of phosphorus availability (2004, background): “Several lines of evidence argue that the total respiratory breakdown of organic matter exceeds that produced by in situ primary production in most lakes (e.g., del Giorgio and Peters 1994; Cole et al. 2000).”
Seasonal shifts between autochthonous and allochthonous carbon contributions to zooplankton diets in a subarctic lake (2011, background): “Such microbial loop– mediated trophic transfer from allochthonous carbon to higher consumers has been suggested to be the main channel to couple terrestrial and aquatic carbon (Jones 1992; Cole et al. 2000).”
Depth-integrated, continuous estimates of metabolism in a clear-water lake (2008, methodology): “In situ sondes fitted with sensitive and accurate oxygen probes have become a useful tool for estimating lake ecosystem metabolism (Cole et al. 2000; Hanson et al. 2003; Lauster et al. 2006).”
Does autochthonous primary production drive variability in bacterial metabolism and growth efficiency in lakes dominated by terrestrial C inputs (2005, methodology): “2D).”
Nutrient Cycling by Animals in Freshwater Ecosystems (2002, background): “These lakes are more likely to be net sinks for CO2 (Schindler et al. 1997, Cole et al. 2000).”
Conservation from the bottom up: forecasting effects of global change on dynamics of organic matter and management needs for river networks (2011, background): “Terrestrial detritus dominates metabolism in many aquatic ecosystems, rendering them net heterotrophic (Cole et al. 2000, Mulholland et al. 2001, Duarte and Prairie 2005).”
Expanding the concept of trophic state in aquatic ecosystems: It’s not just the autotrophs (2007, background): “Further, these microbial methods miss entirely the respiratory contribution of metazoans which can be significant in some ecosystems ( Cole et al., 1988 ).”