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Project Description

The 3rd generation High-Intake Defined Excitation Bathyphotometer (HIDEX G3), is a shipboard profiling instrument package designed to measure bioluminescence and related water parameters for the US Navy.  This project is funded by the Office of Naval Research.

Intellectual Merit

Bioluminescence is a phenomenon present in all of the world’s oceans.  It occurs in marine animals big and small, from single-celled dinoflagellates to menacing angler fish.  For animals in the deep sea, it is the rule, not the exception.

Bioluminescence occurs when two chemicals, Luciferin and Luciferase are combined within a cell.  The resulting byproduct is a blue-green light.  In single-celled plankton such as dinoflagellates, this is triggered by a mechanical stimulus, such as a fish swimming through the water.

This light can be very bright, and as a result poses a tactical threat to coastal military night operations.  Glowing wakes of ships, submarines, and divers can be seen from high vantage points, sometimes even from satellites.

To quantify this phenomenon HBOI engineers have built the world’s most sensitive and sophisticated bioluminescence measurement instrument, the HIDEX G3.  The basic principle is simple … the instrument is lowered over the side of a ship.  While it descends to a maximum of 500m, a high-speed pump pulls water over a metal grid at ~18 l/s.  Once the water hits the grid, the luminescent animals flash.  That flash is recorded in a detection chamber by an array of very sensitive light sensors called Photomultiplier Tubes (PMTs).  In addition to this light data, other parameters about the water are recorded, such as salinity, temperature, depth, chlorophyll concentration, etc.  These parameters help scientists to understand the factors that cause bioluminescence to occur. This data is all compared to physical water samples and video footage collected during the cast, from a carousel sampler and intensified camera on board the HIDEX.

Broader Impacts

The predecessor HIDEX system is now the Naval Oceanographic Office’s benchmark standard for bioluminescence measurement.  The G3 instrument will help to further understand bioluminescence phenomena, allowing better forecasting of bioluminescent events for tactical purposes.  In addition, the HIDEX G3 can be used as a baseline for calibration of other bathyphotometers.  Development of HIDEX also has significant impacts on understanding the ecology of these organisms and the nature of luminescence.  Many of the organisms that cause harmful algal blooms (HABs) such as Red Tide, for example, are also bioluminescent.  The HIDEX G3 has been operating successfully in the field for 3 years, and has recently completed a one year monthly bioluminescence study from Florida to the Bahamas.