Preliminary results from studies of nocturnal bioluminescence with subsurface moored photometers

Spatial and temporal patterns of bioluminescent flashes were recorded from fall 1982 through Spring 1983 by photometers moored offshore in Scripps Canyon, La Jolla, California, USA. From depths between 8 and 90 m, realtime data were transmitted by cable to a laboratory on land approximately one mile (1.7 km) away. In addition, temperature, depth and current velocity and direction were monitored either in real time by direct coupling to a laboratory-based system, or by internal data storage-systems that were retrieved at regular intervals and subsequently analyzed. Our studies showed that our field station is largely uncoupled from wave action effects usually associated with luminescence measurements made from ships. Bioluminescent activity varied greatly both during a single night and between different nights. Vertical profiling of the water column between 8 and 90 m showed evidence of vertical migration, patchiness of distribution and large-scale spatial differences in total bioluminescent activity. Currents had a major impact on patterns of bioluminescent activity; however, sometimes high levels of luminescence were recorded in complete absence of currents. Diel cycles, organism patchiness, the level of downwelling ambient light, and currents appeared to interact in controlling the levels and patterns of bioluminescence.