Marine bioluminescence: measurement by a classical light sensor and related foraging behaviour of a deep diving predator
Résumé
Bioluminescence is produced by a broad range of organisms for defense, predation or communication purposes. Southern elephant seal (SES) vision is adapted to low intensity light with a peak sensitivity, matching the wavelength emitted by myctophid species, one of the main prey of female SES. A total of 11 satellite-tracked female SES were equipped with a Time-Depth-Light 3D-accelerometers (TDR10-X) in order to assess whether bioluminescence could be used by SES to locate their prey. First, we demonstrated experimentally that the TDR10-X light sensor was sensitive enough to detect natural bioluminescence; however, we highlighted a low distance detection of the sensor. Then, we linked the number of Prey Capture Attempts (PCA), assessed from accelerometer data, with the number of detected bioluminescence events. PCA was positively related to bioluminescence, which provides strong support that bioluminescence is involved in predator-prey interactions for these species. However, the limitations of the sensor did not allow us to discern whether bioluminescence (i) provided remote indication of the biological richness of the area to SES, (ii) was emitted as a mechanic reaction, or (iii) was emitted as a defense mechanism in response to SES behaviour.