Lights and sea creatures

[Phenol]

As HID and high-power LED lights are becoming cheaper and more common, I was wondering if there were any concerns about their effect on the behaviour patterns of the fishes and other creatures encountered during night dives.

For example, I suspect a group of divers wielding Light Cannons etc. (not to mention photo/video strobes) probably turns night into day for the 30 min - 1 h they explore a section of a reef. Are there "safe" lights out there that do not unduly stress the animals while ensuring the divers know where they are and where they are going?

 

[Diver0001]

Are there "safe" lights out there that do not unduly stress the animals while ensuring the divers know where they are and where they are going?

Yes, bright lights stress the animals. I made a light once with a 50w Halogen bulb and many of the animals in our locals waters fled from it. I now have a 10w HID light and it's much better for critter watching. I suspect that the more powerful HID lights are also not ideal for watching the animals.

I've heard that aquarium keepers use blue (black) lights to illuminate aquaria for night watching. I doubt that this would be very useful for divers.

R..

 

[Fr3d]

Probally nothing to really worry about, but should watch out for photosensitive marine animals, ie jellyfish. While doing an experiment which involved submerging a light trap just below the surface for 30mins, we ended up with approx 800 individual jellyfish similar to those in the link below :11:

http://www.medusozoa.com/images/carybdea_sp.jpg

 

[Blacthorn]

Has anyone tried using a red filter on the light? I know that with VERY deep submersibles when they use red the animals arent' able to see that spectrum. Shallower critters should be able to see that spectrum, but it might still be less upsetting to them, it would also not cast as far underwater I would think with the way that water absorbs red.

 

[maractwin]

Personally, I do night dives with a relatively dim light. I usually just use the focus assist light on my camera rig. It upsets fish less, allowing me to see more. I do carry a high power light clipped to my BC in case of emergency. But the only time I've actually used that was to pass it off to another diver whose battery had failed.

-Mark

 

[Damselfish]

Animals out at night don't seem to be thrilled about any sort of light, lots slink away or whatever. (Unless of course they use yours to hunt by. :sharks I'm sure it bothers some more than others, or is more dangerous for some.

I don't use any more light than I need, turning a night dive into a day dive kinda defeats the point of a night dive for me. I also try not to shine any hotspot of a light directly on things, use the outer part of the beam instead.