MIT Engineer Builds Instrument to Study Underwater Fluorescence


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Elizabeth Thomson
Email: thomson@mit.edu
Phone: 617-258-5563
MIT Resource Development

CAMBRIDGE, Mass.--While most scuba divers plunge into the underwater
world to escape urban annoyances like fluorescent light, MIT engineer
Charles Mazel dives in search of fluorescence.

Under ultraviolet light, many otherwise drab corals, anemones,
shrimps and other organisms mysteriously fluoresce in brilliant colors.
Such displays are in many circumstances still a mystery, with little
known about what causes the illumination within tissues or the function
of such brilliance.

To study this phenomenon, Dr. Mazel, a research engineer in the
Department of Ocean Engineering, designed and built a prototype
instrument to measure the spectral distributions of underwater
fluorescence. He did so in collaboration with Lydia Chan and Quoc Tran,
undergraduates in the Department of Mechanical Engineering (both have
since graduated).

The device has now caught the eye of researchers who study how
light interacts both with the sea floor and the organisms that live
there. As a result, Dr. Mazel has been using it toward research in the
waters off Southern California and Florida, and will be heading to the
Caribbean this summer.

"The light that comes into the ocean affects what grows and what
pigmentation it has, and that affects light coming off the bottom,"
explains Dr. Mazel, who is also Assistant Director of the Edgerton
Center. Thus, researchers curious about sediments, sea grasses, and
coral reefs look to light to, well, illuminate their subjects.

Much of the gathering and recording of information from marine
environments is accomplished by remote sensing. These techniques for
gathering data include photography, spectral detectors and laser-based
sensing, using platforms ranging from satellites and airplanes to
unmanned vehicles. Such methods allow scientists to rapidly acquire
large amounts of information. However, interpreting the significance of
all this data is another matter.

***********************************************************************
***** Charles Mazel's photographs of fluorescing corals will be
***** part of a two-person show at the headquarters of the National
***** Academy of Sciences in Washington, DC, this spring. Twenty of Dr.
***** Mazel's photographs will be featured in the show, which runs from
***** April 2 to June 28. For more information call (202) 334-2436.
***********************************************************************

By recording measurements of fluorescence from different sources,
Dr. Mazel hopes to understand the biological processes that affect
fluorescence and equip scientists with "a library of signatures" for
interpreting the vast quantities of data available.

The device that Dr. Mazel and colleagues built uses a light source,
filters, and fiber optics to excite the fluorescence of corals and other
organisms. A low-cost spectrometer, which measures incoming light, is
hooked up to a computer that logs and stores the spectral data. While
some instruments measure a limited range of wavelengths, this device,
which Dr. Mazel calls the Benthic Spectrofluorometer, measures the
entire spectrum of light emitted. Housed in two watertight plastic
boxes, the contraption is small enough to be strapped to a diver's wrist
or chest.

Dr. Mazel's investigation of underwater fluorescence began as a
sideline while he was pursuing his master's degree in ocean engineering
at MIT. What started out as qualitative work, limited to visual
observation and photography, turned quantitative -- measuring spectral
distributions of fluorescence -- while he was completing his PhD at
Boston University. During that time, Dr. Mazel conceived of an
instrument for making these measurements underwater instead of having to collect specimens and bring them back to the laboratory.

Dr. Mazel's MIT Sea Grant-funded research has since led to four new
related research projects. In a project funded by the Office of Naval
Research's Environmental Optics Program, Dr. Mazel and ocean engineering graduate student Eran Fux traveled this past summer to Florida's Dry Tortugas with the fluorometer to study both fluorescent and reflected light of corals as part of a multi-disciplinary team.

A Naval Research Lab contract took the researcher to Southern California in October, where he conducted measurements of light reflected from the sea bottom. Mazel also received funding to build a copy of his instrument for a scientist at Western Washington University. That work took Dr. Mazel and Mr. Fux to the Florida Keys in June.

The ONR's Environmental Optics Program has also funded Dr. Mazel to
study fluorescence in the Caribbean through photography, video, and
spectral measurement. That work will be coordinated with efforts to
better understand why coral fluoresces, and why it does so with varied
spectral characteristics, intensity and distribution.


Topics: Oceanography and ocean engineering

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