Lights out

The US Navy is helping oceanographic researchers to develop a device for studying, identifying and mapping creatures that give off chemical-based light, or bioluminescence.

The military has been interested in mapping the phenomenon for some time because when creatures are agitated by a passing submarine or swimmer their light signature can be seen from the surface, giving away the position of the vessel to the enemy.In 1918 bioluminescence gave away the location of the last U-boat sunk by the Allies in World War I.

Although light-producing creatures ranging in size from bacteria to fish are found throughout the oceans, the concentration of organisms is variable.

If navies could understand and predict the creatures’ movements, the planning of covert operations or the detection of enemy vessels could be improved.The technique could also be used to identify toxic algae and the size and migration patterns of fish stock.

‘Bioluminescence is important in revealing the position of swimmers and submarines, hence it has both offensive and defensive applications,’ said bioluminescence expert Dr Edith Widder of Florida’s Harbour Branch Oceanographic Institution, which is working with the US Navy.

She said: ‘The navy has been mapping the oceans for years and this is the final piece of the puzzle. It is also extremely important in mapping the ecology of the seas.’The equipment under development consists of two components.

The High Intake Defined Excitation BathyPhotometer, or HIDEX-BP, is a light-proofed chamber that draws in seawater past a mesh screen. The combined action of the fast-flowing water and hitting the screen causes any bioluminescent creatures to glow.

However, though the level of light can be measured, the machine cannot identify the type of creature responsible.

This is critical, as the same amount of bioluminescence might be produced by a small isolated number of jellyfish or a widely dispersed algae bloom affecting a large area.Researchers are working to couple the device with a miniature camera mounted on the front of the HIDEX-BP to form an identification device that can be used from a boat instead of mounted on an expensive submersible.

This Spatial Plankton Analysis Technique camera will be linked to a computer, and will identify the type and population density of the creatures based on their shape and amount of light produced. This will allow navies and oceanographers to identify and predict the habits of bioluminescent creatures.