Future Directions in Bioluminescence Research

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ABSTRACT

Overview of the last twenty years in marine bioluminescence research

James F. Case

Much of what I have to say this morning I have learned with or from Edith Widder, Mike Latz, Steve Haddock, Peter Herring, David Lapota, Mark Geiger, Cyril Johnson, Casey Moore and, more recently, Christy Herren, Carrie McDougall, Mark Moline and many in ONR, particularly Ron Tipper, Eric Hartwig, Richard Spinrad, Kenneth Ferer, and Richard Lauer.

In any historical talk on this subject homage must immediately be paid to George Clarke of Harvard/WHOI who first subjected a photomultiplier tube to great depths, seeking to measure the penetration of solar light, and instead measuring flashes of bioluminescence and thereby opening a new window on marine bioluminescence. In this talk I emphasize American efforts while recognizing the pioneering efforts of Aiken and Kelley and later of Peter Herring in Great Britain. One must also note the massive and early survey effort mounted by Russian investigators that has continued to the present with an intriguing evolutionary radiation of instrumentation development, albeit recently under difficult circumstances.

The time covered by these comments represents a period of substantial support to marine bioluminescence researchers by the Office of Naval Research as an element of its mission to increase knowledge of the oceans. An appropriate start point is the BIOWATT (1983) research initiative, "Bioluminescence and Optical Variability". This marked a radical change of attitude in ONR. A few years earlier the policy with regard to marine bioluminescence was to find ways for its elimination. In BIOWATT, against a background of modern optical and biological oceanography there was developed a broad emphasis on critical scientific and naval matters, namely:

1. Bioluminescent sources in the marine environment
2. Characteristics of the bioluminescent signal
3. The causes of bioluminescence
4. The dominant absorbers and scatters
5. Patterns of distribution of the dominant light producers
6. Factors maintaining these observed patterns of distribution

This pure science effort paralleled an extensive and long-established program of bioluminescence surveys by the Office of the Oceanographer of the Navy and by applied research on bioluminescence as related to submarine security and surveillance, led by Johns Hopkins Applied Physics Laboratory. The result was an intellectually catalytic interplay of interests from pure science to the most applied, and covering matters ranging from the chemistry of bioluminescence to the most applied techniques of measuring bioluminescence at sea.

The immense variety of bioluminescent sources in the ocean, understanding of which still leaves much to be learned, creates difficult problems for adapting to and utilizing bioluminescence in connection with naval operations. The Navy investment since 1983 in bioluminescence research, together with the work of colleagues abroad has provided a working catalog of the most significant source organisms and in, many instances detailed knowledge of their luminescent properties – color, intensity, kinetics, and modes of excitation and emission under laboratory conditions. Measuring bioluminescence from organisms in the sea in ways that accurately evaluate their potential to produce light is highly complex and perhaps has not yet been optimized. ONR support permitted development at UCSB of the HIDEX series of bioluminescence detectors. These provided for the first time excellent characterization of oceanic bioluminescence potential for mapping purposes. These are still in use by NAVO, NRL-Stennis and Harbor Branch Oceanographic Laboratory. More manageable detector systems referenceable to these instrumental behemoths have been developed to function on many different platforms including moorings and AUVs. Perhaps just over the horizon are applications of new airborne bioluminescence sensors. These promise hugely increased rates of spatial coverage for measurement of surface bioluminescence.

With these tools, and the guidance of oceanographers and modelers there emerges hope of solutions to the most difficult items in the BIOWATT task list – understanding patterns of distribution and prediction of local expressions of bioluminescence. Finally, since BIOWATT, the littoral zone has grown in importance. In this narrow strip bioluminescence clearly is an extremely relevant element of threat management.

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