Future Directions in Bioluminescence Research

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ABSTRACT

Seasonal Correlations of Planktonic Bioluminescence with Zooplankton Biomass and Chlorophyll Fluorescence

David Lapota

SPAWAR Systems Center San Diego, CA 92152-6310

Only recently, are in situ stimulable bioluminescence measurements being evaluated as indicators of both phytoplankton and zooplankton biomass. Simple positive correlations suggest that bioluminescence may be a reasonable indicator of zooplankton biomass in diverse oceanic regimes: sub-arctic and arctic seas, Mediterranean Sea, Persian Gulf, and the Southern California Bight.

Zooplankton displacement volumes, wet weights, and the number of phyto- and zooplankters are positively correlated with bathyphotometer integrated water column bioluminescence to a depth of 100m. Positive correlation coefficients (r) ranged from 0.735 to 0.789 (p<0.001) for samples collected in Vestfjord, Norway, the Beaufort Sea, the Mediterranean Sea, and the western Pacific Ocean. Plankton wet weights were positively correlated with integrated water column bioluminescence to a lesser degree for samples collected in the Southern California Bight and the Persian Gulf (r=0.538 to 0.639, p<0.001, respectively).

Within the Southern California Bight, maximum integrated bioluminescence generally occurred earlier than maximum Chl a and maximum zooplankton wet weights during 1994-1997. When mean integrated bioluminescence values were lagged +1 season later with respect to mean integrated Chl a values, the positive correlation improved (r=0.640, p<0.10). The same improvement in a positive correlation was observed when mean integrated bioluminescence values were lagged +1 season later with respect to mean zooplankton wet weights (r=0.874, p<0.01) which might imply a cause and effect.

The strongest positive correlations between bioluminescence and chlorophyll fluorescence at all stations from 1994-1997 in the Southern California Bight were observed in winter 1995 (r=0.653), spring 1995 (r=0.499), and winter 1997 (r=0.480). It was also observed that as the water column stratifies and becomes more stable, some positive correlations improve, such as bioluminescence and temperature, bioluminescence and chlorophyll fluorescence, bioluminescence and beam attenuation, and chlorophyll fluorescence and beam attenuation.

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