Professor of Organismic and Evolutionary Biology
Harvard University, Department of OEB
"Darnit, I'm A Biologist Not An Engineer: Or...How I Learned To Stop Worrying and Love Deep Sea Biology"
Abstract: The discovery of hydrothermal vents was a turning point in humankind’s understanding of the nature and extent of habitats in Earth’s biosphere. For the last forty years, biologists have studied the intricate relationships that exist among microbes, animals, and the geochemical conditions at hydrothermal vents, hydrocarbon seeps, and other sulfidic habitats.
Despite being one of the most physically and chemically challenging habitats on Earth, vents are home to an extraordinary community of microbes and animals, all of whom depend on the vent chemicals for life. Unlike forests and other terrestrial habitats, in which plants or algae form the base of the food chain, most hydrothermal vents are too deep for sunlight to reach. However, the microbes that live around vents use chemical energy instead of sunlight for energy and carbon fixation, and as such form the base of the food chain in these environments. They grow to high densities within, upon, underneath the vents, and support a lush and vibrant community of animals.
Studying these communities is, at best, a challenge. Many of these habitats are located where pressures reach 250 atmospheres (~3,700 PSI). Balance a minivan on one square inch of your palm, and you’ll see what it means to be under pressure. Temperatures range from near freezing to over 350° C (662° F); approximately the temperature inside your oven while it’s in self-clean mode. Accordingly, the earlier studies were limited by the technologies of the day. Outstanding discoveries were made, from finding the first animal-microbial symbioses to describing the 80 meter tall hydrothermal sulfide “vents”. Not surprisingly, there remains a paucity of data on the physiology and activity of many vent endemic organisms, from the diverse if not enigmatic microbes to the abundant and charismatic tubeworms. Even the spatial and temporal dynamics of vent-derived chemicals is poorly bounded. Gathering these data and placing them into the local and regional context is of paramount importance, especially as we work to understand the factors that govern our ocean’s health. For example, we now know that entire ocean circulates through the hydrothermal vent systems every 70,000 to 200,000 years. Accordingly, vents are responsible for significant proportions of Iron that are in our ocean, a key element needed by all life. They are likely key in providing trace nutrients such as copper and other metals as well. However, the microbes and animals found at vents, which are numerous and highly active, may influence the extent to which these compounds reach the overlying water.
To address these and other long-standing questions, the Girguis lab focus on conducting “omics-informed” experiments to measure metabolic activity (including carbon, sulfur and nitrogen metabolism) in a variety of organisms. We also develop tools to make in situ geo-referenced geochemical measurements around these associations. When appropriate, we extend the application of these technologies to other environs. All together our research efforts are furthering our understanding of the relationship among animals, microbes, and their abiotic surroundings. It is our plan to focus our efforts on regions devoid of deep sea exploration, to bring our technologies to people who do not have access to such tools, and to present our data in the most comprehensible way to those who are responsible for the policies that govern the fate of our ocean and, ultimately, our biosphere.