Characteristics of methanotrophic communities and their physicochemical driving mechanisms in estuarine and nearshore wetlands of Qinghai Lake

Abstract

Methanotrophic communities play a vital role in regulating methane fluxes in wetland ecosystems. This study examined the composition and environmental drivers of methanotrophs in estuarine and nearshore wetlands of the Qinghai Lake basin. Soil samples from six sites across three tributaries showed clear spatial and vertical variation in organic matter, nitrogen forms, and salinity. The Heima River estuarine wetland exhibited the highest methanotrophic diversity and functional potential. Dominant genera included Methylobacter, Methylosinus, and Methylocystis, with site-specific distributions. Redundancy analysis identified soil organic matter, nitrate nitrogen, pH, and electrical conductivity as key factors shaping community structure. These findings reveal how water-salt interactions and nutrient status influence methane-oxidizing microbes, offering insights into carbon cycling dynamics in high-altitude wetlands and supporting ecological restoration efforts in plateau regions.

Keywords: Aquatic biology; Ecology; Geomicrobiology; Microbiology.

Graphical abstract

Figure 1

Spatial variation of soil physicochemical properties and their influence on methanotrophic communities in Qinghai Lake wetlands (A–I) and (J–R) represent soil physicochemical properties in the 0–10 cm and 10–20 cm soil layers, respectively. Specifically (A, J) organic matter content; (B, K) ammonium nitrogen content; (C, L) nitrate nitrogen content; (D, M) available phosphorus content; (E, N) available potassium content; (F, O) pH value; (G, P) electrical conductivity; (H, Q) salinity; (I, R) soil bulk density; (S) the location of Qinghai Lake basin and our test plots; (T) redundancy analysis (RDA) of methane-oxidizing bacterial community and soil physicochemical factors in the 0–10 cm soil layer; (U) redundancy analysis (RDA) of methane-oxidizing bacterial community and soil physicochemical factors in the 10–20 cm soil layer. SOM represents soil organic matter, A-P represents available phosphorus, NO₃-N represents nitrate nitrogen, and BUL represents soil bulk density. Data in (A–I) and (J–R) are represented as mean ± SEM, n = 3 soil samples per site. ∗ and ^# indicate significant differences between the nearshore estuarine wetland and the estuarine wetland, respectively. ∗ and ^# indicate p < 0.05; ∗∗ and ^## indicate p < 0.01; ∗∗∗ and ^### indicate p < 0.001 (n = 3).

Figure 2

OTU distribution and β-diversity of methanotrophic communities in different soil layers of Qinghai Lake wetlands (A) OTU numbers in the 0–10 cm soil layer; (B) OTU numbers in the 10–20 cm soil layer; (C) PCoA analysis of the 0–10 cm soil layer; (D) PCoA analysis of the 10–20 cm soil layer.

Figure 3

Community structure, composition, and key taxonomic differences of methanotrophic communities in different soil layers of Qinghai Lake wetlands (A and B) Genus-level composition of soil methane-oxidizing bacterial communities in the 0–10 cm and 10–20 cm soil layers, respectively; (C, D) heatmap analysis of soil methane-oxidizing bacterial communities in the 0–10 cm and 10–20 cm soil layers, respectively; (E, F) LDA bar charts of soil methane-oxidizing bacterial communities in the 0–10 cm and 10–20 cm soil layers, respectively; (G, H) cladograms of soil methane-oxidizing bacterial communities in the 0–10 cm and 10–20 cm soil layers, respectively.