Project description:Background biology: Global warming has accelerated in recent decades, with the Arctic warming 2–3 times faster than the global average. As a result boreal species are expanding into the Arctic, at a pace reflecting environmental warming. Nevertheless, the poleward expansion of boreal marine species is restricted by their ability to tolerate low water temperatures, and in the case of intertidal species, sub-zero air temperatures during winter. In Greenland, however, the number of days with extreme sub-zero air temperatures has decreased by more than 50% since the 1950’s, suggesting that the low air temperature constraint is weakening. Although boreal intertidal species could potentially benefit from this warmer climate to establish populations in the Arctic, recent work has shown that local intertidal summer air temperatures in Greenland can exceed 36°C. This temperature is above the thermoregulatory capacity of many boreal intertidal species, including the highly abundant blue mussel Mytilus edulis. Therefore will further colonisation of M. edulis in Greenland be inhibited by the increasingly warm summer temperatures. Aim of experiment: Intertidal animals (Greenland blue mussel M. edulis) were sampled in situ on the first warm days of the year from the inner (warmer) and outer (cooler) regions of the Godthåbsfjorden around Nuuk (64°N) to examine the fjord temperature gradient effect. In addition, subtidal M. edulis were also collected and subjected to two acute temperature shocks of 22 and 32°C, which represented common and extreme summer air temperatures for intertidal habitats near Nuuk.
Project description:Over 20% of Earth’s terrestrial surface is underlain by permafrost that represents one of the largest terrestrial carbon pools, with an estimated ~1700 Pg of carbon (C) contained in the upper 3 m of permafrost. Models estimate that C release from thawing permafrost might represent the largest new transfer of C from the biosphere to the atmosphere as the climate warms. Here we investigated microbial community phylogeny, genetic functional potential gene expression, and protein production patterns along a natural thaw gradient, including permafrost, the seasonally thawed active layer and nearby thawed thermokarst bog, using a combination of molecular “omics” approaches: metagenomics (MG), metatranscriptomics (MT) and metaproteomics (MP). Highlights from these analyses reveal energy yielding microbial processes and potential strategies for microbial survival in permafrost soils, and linkages between biogeochemical process rates and –omics measurements. The results provide new knowledge about microbial life and activity potential in permafrost, the potential importance of iron reduction as a survival strategy under frozen conditions in mineral soils, and the importance of methanogenesis following thaw. The multi-omics strategy demonstrated here enables better mechanistic understanding of the ecological strategies utilized by soil microbial communities in response to climate change. Associated metagenomics data available at the EBI Metagenomics portal under the accession number <a href="https://www.ebi.ac.uk/metagenomics/projects/SRP052575">SRP052575</a>.
