Effects of deglaciation on the succession of methanotrophic communities in inland and tidewater glaciers in the high Arctic, Svalbard

The high Arctic region of Svalbard has undergone significant landscape transformations due to accelerated deglaciation driven by climate warming. The expansion of exposed soil surfaces during rapid deglaciation provides new habitats for plants and microorganisms and contributes to ecosystem succession. The primary succession process has the potential to impact methane flux by influencing the activities of methanotrophs and methanogens. While the primary succession of plant communities following glacier retreat has been extensively studied, microbial succession, in particular that of methanotrophs and methanogens, is still poorly understood. Moreover, previous investigations have focused on the forelands of inland or mountainous glaciers, neglecting those of tidewater glaciers that extend to the coastal line. In this study, we investigated the abundance of methanotrophs and methanogens, as well as methanotrophic communities along a 100-year soil chronosequence in the forelands of inland and tidewater glaciers in Svalbard. The abundance of methanotrophs showed a gradual increase with soil age in both glacier types, while the abundance of methanogens exhibited significant differences only in tidewater glaciers. Our results revealed clear trends in the structure of methanotrophic communities with an increase in their diversity during the deglaciation process in both glacier types. These trends were mediated by changes in soil physicochemical properties such as soil organic carbon and total nitrogen. Our findings indicate that methane oxidation may be enhanced by the increase in the abundance and diversity of methanotrophs in both glacier types throughout the successional stages, and that carbon and nitrogen contents play a crucial role in structuring the community at different stages of succession in the glacier forefield. These insights significantly contribute to our understanding of microbial dynamics during deglaciation and their implications for methane dynamics in the high Arctic.