Methane and Primary Productivity in Lakes: Divergence of Temporal and Spatial Relationships

Abstract

In lakes, the production and emission of methane (CH 4) have been linked to lake trophic status. However, few studies have quantified the temporal response of lake CH 4 dynamics to primary productivity at the ecosystem scale or considered how the response may vary across lakes. Here, we investigate relationships between lake CH 4 dynamics and ecosystem primary productivity across both space and time using data from five lakes in northern Wisconsin, USA. From 2014 to 2019, we estimated hypolimnetic CH 4 storage rates for each lake using timeseries of hypolimnetic CH 4 concentration through the summer season. Across all lakes and years, hypolimnetic CH 4 storage ranged from <0.001 to 7.6 mmol CH 4 m −2 d −1 and was positively related to the mean summer rate of gross primary productivity (GPP). However, within-lake temporal responses to GPP diverged from the spatial relationship, and GPP was not a significant predictor of interannual variability in CH 4 storage at the lake scale. Using these data, we consider how and why temporal responses may differ from spatial patterns and demonstrate how extrapolating cross-lake relationships for prediction at the lake scale may substantially overestimate the rate of change of CH 4 dynamics in response to lake primary productivity. We conclude that future predictions of lake-mediated climate feedbacks in response to a shifting distribution of trophic status should incorporate both varying lake responses and the temporal scale of change. Plain Language Summary Many lakes produce substantial amounts of methane, a potent greenhouse gas. Previous research has found that more methane is produced from lakes with high algal biomass. However, little is known about how methane dynamics from a single lake respond to annual changes in algal biomass. By examining lake methane dynamics and metrics of algal biomass from five lakes across 5 years, we find that within-lake responses of methane dynamics do not align with the across-lake patterns we see when comparing different lakes. Within-lake methane responses were different between lakes and were undetectable in some lakes. Understanding the temporal scale of how lakes respond to changes in algal biomas is important for predicting the role of lakes for producing methane under future environmental change scenarios.

Lake Sediments From Littoral and Profundal Zones are Heterogeneous but Equivalent Sources of Methane Produced by Distinct Methanogenic Communities—A Case Study From Lake Remoray

“…The literature shows that methane production rates depend on the amount, nature, and composition of OM inputs (Berberich et al, 2020;Bertolet et al, 2020;Duc et al, 2010;Grasset et al, 2018). In a controlled experiment, West et al ( 2012) found higher methane production rates following algal biomass input than terrestrial carbon addition whereas methanogenesis potential was similar between conditions.…”

Lake Sediment Methane Responses to Organic Matter are Related to Microbial Community Composition in Experimental Microcosms

“…It is worth noting that we also tested for effects of preexisting OM conditions on ΔCH 4 production, as previous work has hypothesized that temporal response of lake CH 4 production to eutrophication may be related to current or historical trophic state (Bertolet et al, 2020;Yang et al, 2020). However, we found that there were no significant correlations between the strength of the response and metrics of preexisting OM availability (sediment OM % and water column chl a; Table 2).…”

“…Lake CH 4 production and emission are consistently positively related to lake primary productivity and trophic status, but, in both laboratory and field scenarios, there exists large variation in the magnitude of the temporal response of CH 4 dynamics to increases in OM (West et al, 2015;Yakimovich et al, 2018;Bertolet et al, 2020;Yang et al, 2020). Understanding sources of FIGURE 1 | First two principal coordinates of the methanogen community composition (A) and the non-methanogen community composition (B).…”

“…Thus, the global eutrophication of inland waters is expected to increase lake CH 4 emissions (Davidson et al, 2018;DelSontro et al, 2018;Sepulveda-Jauregui et al, 2018;Beaulieu et al, 2019). However, the magnitude of the response of lake CH 4 dynamics to increases in autochthonous OM has been shown to differ across lakes at both the laboratory (West et al, 2015) and ecosystem (Bertolet et al, 2020) scales. Determining sources of variation in the relationship between autochthonous OM and lake CH 4 production is thus essential for constraining future predictions of lake CH 4 dynamics.…”

Spatial heterogeneity of methane concentration, diffusion and production potential, and methanogen community abundance and diversity in sediments from Lake Remoray (France)

“…The literature shows that methane production rates depend on the amount, nature and composition of OM inputs [20,[53][54][55]. In a controlled experiment, West et al (2012) found higher methane production rates following algal biomass input than terrestrial carbon addition whereas methanogenesis potential was similar between conditions.…”