Emergent Macrophytes Alter the Sediment Composition in a Small, Shallow Subtropical Lake: Implications for Methane Emission

Abstract

Aquatic macrophytes in shallow lakes emit high levels of methane. We hypothesize that the presence of emergent aquatic macrophytes in an artificial shallow lake promotes important input of autochthonous organic matter (OM) in sediment and higher levels of methane emission via bubbles. Samplings were performed at three sites in a small, shallow subtropical lake: (1) one station in the limnetic region and (2) -(3) two stations in the littoral region ((2) inside and (3) outside aquatic macrophyte stands). A higher concentration of OM was observed at the macrophyte station, and within this site, a higher methane concentration was observed in the sediment. These results could explain the methane ebullition values at macrophyte sites. At the macrophyte station, methane emission via bubbles contributed 17% to 56% of the total methane emission; however, at the other stations, its contribution via bubbles, was lower than 1%. This research confirmed the importance of emergent macrophytes at Polegar Lake as a source of OM in sediment and methane emission via bubbles. Further, we could confirm the positive effects of temperature on methane emission, mainly by bubbles.

The Magnitude and Drivers of Methane Ebullition and Diffusion Vary on a Longitudinal Gradient in a Small Freshwater Reservoir

“…For example, we were unable to measure transect-specific nutrient concentrations (e.g., nitrogen and phosphorus), which are known to be positively related to ebullition by stimulating phytoplankton growth (Davidson et al, 2018). We also did not quantitatively measure aquatic plant abundance, which has been 10.1029/2019JG005205 associated with CH 4 ebullition (Marinho et al, 2015) and diffusion (Attermeyer et al, 2016), though we note qualitatively that plant abundance at our transect sites was minimal. Diffusion was also likely underestimated because we assumed that diffusive rates were the same over a diel period when scaled from the short duration of time that we measured efflux.…”

Climate‐Sensitive Controls on Large Spring Emissions of CH4 and CO2 From Northern Lakes

“…Empirical activation energies were 1.00 ± 0.17 eV for diffusion, similar to ecosystem‐level estimates for wetlands and aquatic environments (0.96 ± 0.10 eV) (Yvon‐Durocher et al, ) and 1.37 ± 0.10 eV for ebullition (mean ± 95% confidence interval). Ebullition rates were highest in shallow Villasjön and the littoral areas of Mellersta Harrsjön (Figure ), perhaps because a larger fraction of insolation reaching the bottom led to warmer sediments in shallow (≤2 m) compared to deeper zones (Bastviken et al, ; Wik et al, ), and/or because of more labile carbon input from macrophytes (Marinho et al, ) and runoff (Olefeldt & Roulet, ).…”

Lagoas costeiras como um laboratório natural para o estudo do metano: ferramenta para o manejo ecossistêmico de corpos d´água

“…Essa ocorrência é justificada, pois as lagoas costeiras são ecossistemas rasos e pequenos, possibilitando a formação de extensas regiões litorâneas, que podem ser colonizadas por diferentes comunidades de macrófitas aquáticas (Figura 12). Nesses ecossistemas, essas plantas encontram condições tão favoráveis para seu desenvolvimento que tornam a região litorânea o compartimento mais produtivo do ecossistema, podendo influenciar o ambiente lacustre como um todo, além de alterarem de forma significativa a estrutura do sedimento 19,20,21 . Outro fator importante em relação a essas comunidades de plantas é que elas se desenvolvem em uma zona de transição entre o ecossistema terrestre e o aquático, regulando os fluxos de matéria e energia entre esses ambientes 22 .…”