Speaker – John Paul Balmonte, Marine Science, Assistant Professor, Lehigh University, Department of Earth and Environmental Sciences (host – Ryan Paerl)  Zoom

Seminar Title – New insights into microbial remineralization of organic matter: pressure effects from surface waters to the deep sea and year-long trends in the high Arctic

Abstract – The rates at which marine microbial communities degrade, incorporate into biomass, and remineralize organic matter along spatiotemporal gradients sets the efficiency of the microbial loop and the biological carbon pump. However, these process rates are infrequently measured at certain conditions, locations, and times that are necessary to advance our understanding of microbial roles and environmental drivers in the carbon cycle. Here, I will present and focus specifically on our group’s recent efforts to quantify the effects of increasing hydrostatic pressure on various steps of marine organic matter remineralization, as well as the efficiency of these processes over an annual cycle with weekly resolution in the Arctic. The work on pressure effects spans sites from—and hydrostatic pressures relevant to—surface to hadal waters and sediments, whereas the work on the year-long, weekly resolved time series was conducted in Kongsfjorden, a fjord in Svalbard. Findings from these two separate vignettes will be discussed both in the context of their potential influences on carbon budgets as well as on their implications for the structuring of microbial communities.