Colleen Cavanaugh

Colleen Marie Cavanaugh is an American academic microbiologist best known for her studies of hydrothermal vent ecosystems. As of 2002, she is the Edward C. Jeffrey Professor of Biology in the Department of Organismic and Evolutionary Biology at Harvard University and is affiliated with the Marine Biological Laboratory and the Woods Hole Oceanographic Institution. Cavanaugh was the first to propose that the deep-sea giant tube worm, ''Riftia pachyptila'', obtains its food from bacteria living within its cells, an insight which she had as a graduate student at Harvard. Significantly, she made the connection that these chemoautotrophic bacteria were able to play this role through their use of chemosynthesis, the biological oxidation of inorganic compounds (e.g., hydrogen sulfide) to synthesize organic matter from very simple carbon-containing molecules, thus allowing organisms such as the bacteria (and dependent organisms such as tube worms) to exist in deep ocean without sunlight.

Early life and education

Cavanaugh was born in Detroit, Michigan, in 1953.

Cavanaugh received her undergraduate degree from the University of Michigan in 1977, where she initially studied music but ultimately majored in ecology. She says her life changed direction in her sophomore year when she heard about a course in marine ecology at the oceanographic center in Woods Hole, Massachusetts. There, her work involved wading out into chilly waters to study the mating habits of horseshoe crabs, and she described herself as "allingin love" with the relaxed camaraderie and exchange of ideas between biologists, geologists, and scientists from other disciplines. Cavanaugh took a Marine Ecology course as an undergraduate offered by the University of Michigan, stayed in Woods Hole afterwards (as her car needed repair) looking for a job, and ultimately replaced a "no show" in a Boston University undergraduate research program, which returned her to work with local horseshoe crabs.

Cavanaugh then moved to Cape Cod to work at the Marine Biological Laboratory at Woods Hole. During the next two years the focus of her attention shifted from Crustacea to bacteria, "creatures that impressed her for their ability to live anywhere."

Graduate training

Cavanaugh pursued her graduate training in biology at Harvard University, in association with the Museum of Comparative Zoology. She entered Harvard in the fall of 1979, earning an M.A. in 1981 and graduating with her PhD in biology in 1985. Her Ph.D. dissertation, entitled ''Symbiosis of chemoautotrophic bacteria and marine invertebrates'', was accepted in 1985.

Discovery of chemosynthesis in tube worms

By one account, Cavanaugh was attending a lecture by Meredith L. Jones, curator of worms at the Smithsonian Institution, shortly after she began her graduate studies. Jones was discussing the giant tube worm, a creature lacking both mouth and gut, where the challenge was to understand how it survived. Jones mentioned elemental sulfur crystals within the worms gut; Cavanaugh states that "It was at that point that I jumped up and said, 'Well, it's perfectly clear! They must have sulphur-oxidising bacteria inside their bodies'". Jones apparently told her to sit down, but provided Cavanaugh with a specimen captured by a research submarine working on the bottom of the Pacific Ocean. Cavanaugh eventually substantiated her case.

The ''Harvard Gazette'' describes Cavanaugh's pioneering study of these unique creatures:

As a first-year graduate student, she discovered what makes life possible... where the sun never shines, heretemperatures can exceed 250 degrees F, and herethe ocean exerts pressures of thousands of pounds on every square inch of an animal's body. Giant worms, huge clams and mussels, and strange shrimp thrive in such conditions because of one-celled bacteria who live on and inside them. The bacteria turn sulfur, methane, and other inedibles into organic molecules that their hosts feed on.

Cavanaugh went on to publish the results of the further work that began to substantiate the discovery, writing from the Museum of Comparative Zoology at Harvard, as first of a five author paper, a short 1981 ''Science'' report with Stephen L. Gardiner and Meredith L. Jones of the Smithsonian Institution, and Holgar W. Jannasch and John B. Waterbury at Woods Hole (see Significant publications).

Career

Cavanaugh's first appointment was as a Junior Fellowship in the Society of Fellows at Harvard University, in 1986–1989. This was followed by elevation to assistant professorship in 1989, and associate professor in 1993. In 1995, she was granted tenure as a full professor "for erdiscoveries and her reputation as a teacher and mentor." Cavanaugh was the Co-director of the Harvard Microbial Sciences Initiative for 17 years.

Research and outreach highlights

Cavanaugh has continued to build her career on the study of hydrothermal vent ecology. Cavanaugh went on to discover similar symbiotic partnerships among Solemyidae clams living in shallow eelgrass