ArCH4ives built and expanded on a unique set of Holocene lake sediment cores spreading along major environmental gradients in Arctic landscapes, a design which aimed to control for the different catchment-specific processes that may have influenced microbial communities in the past, and isolate the influence of climate on their ecology. This interdisciplinary approach was supported by the analysis of complementary paleoecological proxies for other important components of the carbon cycle in Arctic watersheds via collaborations with international partners.
At all selected sites, including newly acquired sequences from the Godthåbsfjord region, Southwest Greenland, we used an optimised 'shotgun' sequencing approach to acquire the microbial community profiles. So far, this strategy yielded ecologically relevant information on the diversity and function of major groups of both CH4 producers (Archaea) and consumers (Bacteria: methanotrophs Type I and Type II), but also on other groups of microbes (Cyanobacteria) and higher organisms including zooplankters (Copepods, Ostracods and Cladocerans), plants (aquatic and terrestrial) and fish (Atlantic salmon, Three-spined stickleback). Changes in the community structure of CH4-microbes effectively reflected major environmental changes that occurred at the sites over the Holocene, however additional analyses are required to determine the impact of climate change alone on these changes.
These results were presented at two well-attended international conferences in the field (IAL-IAH and ArcticNet ASM2018).
