Future Directions in Bioluminescence Research

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ABSTRACT

Bioluminescence Exercises at LEO-15: Summer 1999

Mark A. Moline¹, Paul Bissett², James Case³, Scott Glenn⁴, Christy Herren³ and Oscar Schofield⁴

1. Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA 93407
2. Florida Environmental Research Institute, 4807 Bayshore Blvd. Suite 101, Tampa, FL 33611
3. Marine Science Institute, University of California, Santa Barbara, CA 93106
4. Coastal Ocean Observation Laboratory, IMCS, Rutgers University, New Brunswick, NJ 08901

The advent of autonomous underwater vehicle (AUV) technology offers a great deal of potential to define the spatial variability of bioluminescence given the availability of small relatively compact bathyphotometers. The goal of this presentation is to discuss the results from an AUV bioluminescence survey conducted at the Long Term Ecosystem Observatory (LEO-15) during the summer of 1999. The Remote Environmental Monitoring UnitS (REMUS) AUV deployment was conducted ~5km off the coast during a Coastal Predictive Skill experiment which provided ancillary physical/optical measurements and a context in which to interpret the observed patterns. The ~300 x 500m REMUS deployment area was nested within a larger 2 x 4km grid where 24 profiles for bioluminescence and other optical and physical measurements were made.

The large scale grid showed high maximum bioluminescence potential of 3.4E11 photons/sec/L from 2 to 12m in the southern third of the grid. These patterns were consistent with warmer water being advected from the southwest towards the northeast along a clockwise coastal eddy as evident from ADCP and CODAR current data. The bioluminescence measurements were not found to correlate with absorption, scattering, attenuation or flourescence. The bioluminescence structure from the single grid profile taken within the REMUS deployment volume was consistent with the average vertical structure collected from the REMUS bathyphotometer. The two REMUS deployment volumes also showed a decoupling between bioluminescence and flourescence measurements taken from the AUV, suggesting that organisms associated with this luminescence signal were heterotrophic. The distribution of autotrophs were restricted to the upper 3.5m of the water column. The second REMUS deployment (3 hours after sunset) showed an increase in the surface bioluminescence compared to the first deployment (1 hour after sunset) with no change in the vertical structure of flourescence and may indicate vertical migration of the heterotrophic organisms.

This study provided the first successful demonstration of a REMUS bathyphotometer deployment and illustrated the utility in these new versatile technologies in providing high-resolution bioluminescence data. Future deployments of this vehicle within the LEO network and elsewhere will help to define the processes responsible for the structure of bioluminescence patterns in the coastal ocean.

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