There are almost as many microbes in a gallon of seawater as there are people on Earth. And just like people on Earth, these microbes need to work together to get food, stay healthy and defend themselves. But unlike people, which use words and text to communicate, microbes exchange information by sending and receiving molecules. We call these molecules “infochemicals” and our research project is focused on using high-tech approaches borrowed from biomedical researchers and crime-scene investigators to begin to understand the infochemical languages used by microbes in the sea. Our ultimate goal is to make or isolate the infochemicals in the laboratory, and then conduct experiments where we add the infochemicals back to seawater in an effort to try to communicate directly microbes. We suspect that some of the infochemicals will change the way that microbes behave, and this will tell us a lot about what all those microbes in the ocean are doing.
Major strides have been made in understanding the genetic and molecular bases of resource acquisition (i.e., ‘bottom-up’) and mortality (i.e., ‘top-down’) in key marine microbes. However, these advances have yet to challenge the canonical view legitimately that the species composition and biogeochemical function of microbial groups in the upper ocean are controlled by a balance of bottom-up and top-down ecosystem controls. Our project will explore the long-ago recognized, but largely unexplored potential for ‘infochemical’ signals to control microbial interactions, and, thus, biogeochemical fluxes in the open ocean. Our research will focus on the export of biogenic silica and calcium carbonate (and concomitant export of carbon and nutrients), processes that have largely eluded explanation by using classic bottom-up or top-down paradigms. Recent technological advances in mass spectrometry, cell imaging/sorting, and in situ assays for cell specific physiology will allow us to assess the function of novel infochemicals at ecologically relevant concentrations. The field component of our project will focus on plankton bloom dynamics in the North Atlantic Ocean; from the Sargasso Sea to the Norwegian Sea, North Atlantic plankton blooms compose some of the largest biological events in the ocean and drive massive fluxes of carbon and nutrients.
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