Colleen Cavanaugh | |
---|---|
Born | 1953 (age 69–70) |
Nationality | American |
Alma mater | Harvard University |
Occupation | microbiologist |
Known for | studies of hydrothermal vent ecosystems |
Scientific career | |
Thesis | Symbiosis of chemoautotrophic bacteria and marine invertebrates (1985) |
Colleen Marie Cavanaugh is an American academic microbiologist best known for her studies of hydrothermal vent ecosystems. [1] 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. [2] 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. [3] 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. [4]
Cavanaugh was born in Detroit, Michigan, in 1953. [5]
Cavanaugh received her undergraduate degree from the University of Michigan in 1977, where she initially studied music but ultimately majored in ecology. [6] 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 "[falling] in love" with the relaxed camaraderie and exchange of ideas between biologists, geologists, and scientists from other disciplines. [3] 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." [3]
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. [6] [7] Her Ph.D. dissertation, entitled Symbiosis of chemoautotrophic bacteria and marine invertebrates, was accepted in 1985. [8]
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'". [6] Jones apparently told her to sit down, [6] 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, [where] temperatures can exceed 250 degrees F, and [where] the 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. [3]
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).
Cavanaugh's first appointment was as a Junior Fellowship in the Society of Fellows at Harvard University, in 1986–1989. [9] 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 [her] discoveries and her reputation as a teacher and mentor." [3] Cavanaugh was the Co-director of the Harvard Microbial Sciences Initiative [10] for 17 years. [11] [12]
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 beds and mudflats along the New England coast, and in shrimp near sub-sea springs in the middle of the Atlantic. [3]
Cavanaugh believes that life on Earth may have started under similar conditions and says "the idea makes sense because some of the oldest forms of free-living bacteria show signs of being heat-loving organisms." [3] Cavanaugh's work has made the scientific community rethink the "warm chicken soup" theory of life's origins in which the accumulation of organic molecules in shallow waters was a result of lightning electricity.
Cavanaugh's discoveries of the biology of the deep Pacific Ocean were made in a Cambridge, Massachusetts (Harvard) laboratory, and she worked on marine life in the laboratory and on board ships for twelve years before securing a place on the deep-diving submarine Alvin ; she went to the bottom of the Gulf of Mexico, off the Florida coast, for the first time in 1992. According to the Harvard Gazette article:
Not many people have visited with 6-foot-long, bright red worms on the boiling bottom of the ocean. It sounds like a Jules Verne fantasy, but newly tenured Professor of Biology Colleen Cavanaugh has seen these and other strange creatures on voyages to the bottom of the deep sea. [3]
She later participated in more "Extreme Expeditions"—such as a dive to a depth of 8,200 feet off the west coast of Mexico [3] to collect tube worms and their bacteria, the chemically-rich fluids that flow out of the vents, and mineral samples from the deep sea ocean floor. [13] Cavanaugh, who has been called "a scientific Captain Nemo." [3] is prominent in her field of biology. Robert Kunzig, in describing her work for a 2001 Discover magazine article, writes of her visit to "a hot crack in the Earth under the Indian Ocean":
Biologists who study the physiology of organisms are under time pressure: They must dissect the organisms before they deteriorate. Colleen Cavanaugh, a microbiologist from Harvard, needs animals that are alive and not starved; once they've been away from their vent too long, even if they've been sitting in a box on the ocean floor, they start to digest the symbiotic bacteria in which she is interested. [14]
As reported in February 2000, Cavanaugh is the discoverer of a new species of deep-dwelling mussel in the Gulf of Mexico that shares its body with symbiotic bacteria that feed on methane. [3] She joined Craig Smith of the University of Hawaii and other colleagues in a Nature report on a NOAA National Undersea Research Program study at its West Coast and Polar Regions Center (at the University of Alaska, Fairbanks), regarding how whale corpses that drop to the bottom of the ocean—and their bones in particular—play an important role in ocean floor ecology. [15] [16] [17]
The Cavanaugh Laboratory at Harvard works on a number of projects related to bacterial symbiosis in marine invertebrates from deep sea hydrothermal vents, methane seeps, and coastal reducing sediments. Researchers there have a special interest in characterizing the metabolic and genetic capabilities of symbionts, their evolutionary relationships with free-living bacteria, and the co-evolution of symbiont and host. [18]
Siboglinidae is a family of polychaete annelid worms whose members made up the former phyla Pogonophora and Vestimentifera. The family is composed of about 100 species of vermiform creatures which live in thin tubes buried in sediments (Pogonophora) or in tubes attached to hard substratum (Vestimentifera) at ocean depths ranging from 100 to 10,000 m. They can also be found in association with hydrothermal vents, methane seeps, sunken plant material, and whale carcasses.
Any worm that lives in a marine environment is considered a marine worm. Marine worms are found in several different phyla, including the Platyhelminthes, Nematoda, Annelida, Chaetognatha, Hemichordata, and Phoronida. For a list of marine animals that have been called "sea worms", see sea worm.
In biochemistry, chemosynthesis is the biological conversion of one or more carbon-containing molecules and nutrients into organic matter using the oxidation of inorganic compounds or ferrous ions as a source of energy, rather than sunlight, as in photosynthesis. Chemoautotrophs, organisms that obtain carbon from carbon dioxide through chemosynthesis, are phylogenetically diverse. Groups that include conspicuous or biogeochemically-important taxa include the sulfur-oxidizing Gammaproteobacteria, the Campylobacterota, the Aquificota, the methanogenic archaea, and the neutrophilic iron-oxidizing bacteria.
A hydrothermal vent is a fissure on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hotspots. Hydrothermal deposits are rocks and mineral ore deposits formed by the action of hydrothermal vents.
A cold seep is an area of the ocean floor where hydrogen sulfide, methane and other hydrocarbon-rich fluid seepage occurs, often in the form of a brine pool. Cold does not mean that the temperature of the seepage is lower than that of the surrounding sea water. On the contrary, its temperature is often slightly higher. The "cold" is relative to the very warm conditions of a hydrothermal vent. Cold seeps constitute a biome supporting several endemic species.
Riftia pachyptila, commonly known as the giant tube worm and less commonly known as the Giant beardworm, is a marine invertebrate in the phylum Annelida related to tube worms commonly found in the intertidal and pelagic zones. R. pachyptila lives on the floor of the Pacific Ocean near hydrothermal vents, the vents provide a natural ambient temperature in their environment ranging from 2 to 30 °C, at the same time it can tolerate extremely high hydrogen sulfide levels. These worms can reach a length of 3 m, and their tubular bodies have a diameter of 4 cm (1.6 in).
The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 metres or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combination of low temperatures, darkness and high pressure. The deep sea is considered the least explored Earth biome, with the extreme conditions making the environment difficult to access and explore.
Gammaproteobacteria is a class of bacteria in the phylum Pseudomonadota. It contains about 250 genera, which makes it the most genus-rich taxon of the Prokaryotes. Several medically, ecologically, and scientifically important groups of bacteria belong to this class. It is composed by all Gram-negative microbes and is the most phylogenetically and physiologically diverse class of Proteobacteria.
The Endeavour Hydrothermal Vents are a group of hydrothermal vents in the north-eastern Pacific Ocean, located 260 kilometres (160 mi) southwest of Vancouver Island, British Columbia, Canada. The vent field lies 2,250 metres (7,380 ft) below sea level on the northern Endeavour segment of the Juan de Fuca Ridge. In 1982, dredged sulfide samples were recovered from the area covered in small tube worms and prompted a return to the vent field in August 1984, where the active vent field was confirmed by HOV Alvin on leg 10 of cruise AII-112.
A deep-sea community is any community of organisms associated by a shared habitat in the deep sea. Deep sea communities remain largely unexplored, due to the technological and logistical challenges and expense involved in visiting this remote biome. Because of the unique challenges, it was long believed that little life existed in this hostile environment. Since the 19th century however, research has demonstrated that significant biodiversity exists in the deep sea.
A trophosome is a highly vascularised organ found in some animals that houses symbiotic bacteria that provide food for their host. Trophosomes are located in the coelomic cavity in the vestimentiferan tube worms and in symbiotic flatworms of the genus Paracatenula.
Marine microorganisms are defined by their habitat as microorganisms living in a marine environment, that is, in the saltwater of a sea or ocean or the brackish water of a coastal estuary. A microorganism is any microscopic living organism or virus, that is too small to see with the unaided human eye without magnification. Microorganisms are very diverse. They can be single-celled or multicellular and include bacteria, archaea, viruses and most protozoa, as well as some fungi, algae, and animals, such as rotifers and copepods. Many macroscopic animals and plants have microscopic juvenile stages. Some microbiologists also classify viruses as microorganisms, but others consider these as non-living.
Cindy Lee Van Dover is the Harvey Smith Professor of Biological Oceanography and chair of the Division of Marine Science and Conservation at Duke University. She is also the director of the Duke University Marine Laboratory. Her primary area of research is oceanography, but she also studies biodiversity, biogeochemistry, conservation biology, ecology, and marine science.
Bathymodiolus thermophilus is a species of large, deep water mussel, a marine bivalve mollusc in the family Mytilidae, the true mussels. The species was discovered at abyssal depths when submersible vehicles such as DSV Alvin began exploring the deep ocean. It occurs on the sea bed, often in great numbers, close to hydrothermal vents where hot, sulphur-rich water wells up through the floor of the Pacific Ocean.
Microbial symbiosis in marine animals was not discovered until 1981. In the time following, symbiotic relationships between marine invertebrates and chemoautotrophic bacteria have been found in a variety of ecosystems, ranging from shallow coastal waters to deep-sea hydrothermal vents. Symbiosis is a way for marine organisms to find creative ways to survive in a very dynamic environment. They are different in relation to how dependent the organisms are on each other or how they are associated. It is also considered a selective force behind evolution in some scientific aspects. The symbiotic relationships of organisms has the ability to change behavior, morphology and metabolic pathways. With increased recognition and research, new terminology also arises, such as holobiont, which the relationship between a host and its symbionts as one grouping. Many scientists will look at the hologenome, which is the combined genetic information of the host and its symbionts. These terms are more commonly used to describe microbial symbionts.
Nicole Dubilier is a marine microbiologist and director of the Symbiosis Department at the Max Planck Institute for Marine Microbiology since 2013 and a Professor of Microbial Symbioses at the University of Bremen. She is a pioneer in ecological and evolutionary symbiotic relationships between sea animals and their microbial partners inhabiting environments that harbour low nutrient concentrations. She was responsible for the discovery of a new form of symbiosis between two kinds of bacteria and the marine oligochaete Olavius algarvensis.
Charles R. Fisher "Chuck" is a marine biologist, microbial ecologist, and leader in the field of autotrophic symbiosis in deep sea cold seeps and hydrothermal vents. He is Professor Emeritus and Distinguished Senior Scholar of Biology at Pennsylvania State University. Dr. Fisher has authored/coauthored over 100 publications in journals such as Nature, Oceanography, and PNAS among others. He heads the Fisher Deep-Sea Lab at Penn State, which primarily investigates the physiological ecology of the major chemoautotrophic symbiont-containing fauna in the deep ocean environment. The lab works closely with other interdisciplinary researchers on expeditions to research sites at cold seeps in the Gulf of Mexico and hydrothermal vent sites on the East Pacific Rise, the Juan de Fuca Ridge, and in the Lau back-arc Basin.
The hydrothermal vent microbial community includes all unicellular organisms that live and reproduce in a chemically distinct area around hydrothermal vents. These include organisms in the microbial mat, free floating cells, or bacteria in an endosymbiotic relationship with animals. Chemolithoautotrophic bacteria derive nutrients and energy from the geological activity at Hydrothermal vents to fix carbon into organic forms. Viruses are also a part of the hydrothermal vent microbial community and their influence on the microbial ecology in these ecosystems is a burgeoning field of research.
All animals on Earth form associations with microorganisms, including protists, bacteria, archaea, fungi, and viruses. In the ocean, animal–microbial relationships were historically explored in single host–symbiont systems. However, new explorations into the diversity of marine microorganisms associating with diverse marine animal hosts is moving the field into studies that address interactions between the animal host and a more multi-member microbiome. The potential for microbiomes to influence the health, physiology, behavior, and ecology of marine animals could alter current understandings of how marine animals adapt to change, and especially the growing climate-related and anthropogenic-induced changes already impacting the ocean environment.
Peter R. Girguis is a professor in the department of Organismic and Evolutionary Biology at Harvard University, where he leads a lab that studies animals and microbes that live in extreme environments. He and his lab also develop novel underwater instruments such as underwater mass spectrometers. Girguis was the founder and Chief Technology Officer of Trophos Energy from 2010 to 2012, which focused on commercializing microbial fuel cell technologies. The company was bought by Teledyne Benthos in 2012. Girguis currently serves as a board member of the Ocean Exploration Trust and the Schmidt Marine Technology Partners.
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