Viruses in marine sediments: a review of their effect on biogeochemistry and microbial interactions

Viruses are known to impact the flow of carbon through the environment, while also impacting the microbial community around them. While this has been reexamined in recent years in the marine water column, viral impacts on marine sediments, the microbes, and carbon contained within are due for a reassessment. This review synthesizes findings from studies on marine sediment microbial communities to examine the extent of viral contribution to biogeochemical cycling, through ecological impacts as well as through cell lysis. Viruses have been shown to increase metabolic activity within the sediment microbial community as well as increase biodiversity, improving the range and ability of microbial communities to degrade organic matter. Viruses have also been found to have more direct effects on sedimentary geochemistry, with viral-mediated cell lysis allowing for the release of organic matter into the sediment while also being able to act as reservoirs for biologically relevant chemicals such as dissolved organic phosphorus. Viruses have been shown to impact the biogeochemistry of buried marine sediment, with less attention being paid to freshwater sediments and surficial marsh sediments. The interest in viral activities in sediments can help us to understand the drivers of biotic contributions to diagenesis.