Baltic marine sediment metagenome

Metagenomes were sequenced from sediment samples collected during the International Ocean Discovery Program Expedition 347, "Baltic Sea Paleoenvironment". The sediments were retrieved from as far as 84.4 meters below the seafloor. They vary in age, organic carbon content, salinity, and other parameters that reflect the changing Baltic environment during the transition from the last ice age and throughout the Holocene. The Baltic Sea environment has a very dynamic history, having transitioned from a period of freshwater and low organic carbon deposition during the last glaciation to the modern Holocene period of brackish-marine water and high organic carbon. These climatic changes are reflected in the sediment record, and IODP 347 in 2013 was the first-ever scientific drilling expedition to the Baltic to retrieve high-resolution sediment cores documenting this history. The Baltic Sea is thus an excellent natural laboratory for understanding how microbial communities may shift in response to changing conditions in the deep subsurface.