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Bex

does torch with high lumens will harm sea animals?

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Hi all, 

Just wondering, does torch with high lumens like 15k will harm sea animals or distress them ?

 

Cheers,

Bex

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Hi Bex

I'm not sure you can generalise but it certainly disturbs some.

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Posted (edited)

@Lewis88: the linked description of the PhD thesis says, that very strong flashes (stronger than normal UW flashes) have practically no effect on a certain seahorse species (only at very high flash frequency and duration of exposure, a little effect on feeding behaviour is observed). This conforms previous studies that say that UW flashes are pretty undisturbing the animals. Not so the focus light (but red focus light is also save for many animals).

Totally different the lamps, already at much lower intensities than 40k lumen (at 40k lumen maybe they get grilled :sorry:): I do not know of systematic studies, but when using them, one can observe regularily that many animals are disturbed by the permanent light (less as by touching, but they are). Less, if any, effect has red light, that most UW animals cannot perceive...

 

Wolfgang

Edited by Architeuthis

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A really interesting summary, Lewis88 and, I guess, puts some myths to bed. 

Anecdotally, during a year in the Lembeh Straits watching people photo-bombing one particular Gorgonian at 25m, a small group of Bargibanti cleared off. I couldn't help but feel at the time that it was the sheer volume of flashes they were experiencing that made them leave - but it could well have been touching of the fan itself. Certainly the whole area around the coral head was degraded by the sheer volume of divers who visited. 

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That is pretty sad Tim,

In all honesty one must have the most excellent technique to engage in macro photography without some impact on the surrounding area.  

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4 hours ago, Chris Kippax said:

That is pretty sad Tim,

In all honesty one must have the most excellent technique to engage in macro photography without some impact on the surrounding area.  

Yep, totally agree, Chris.

But even then, sheer traffic volumes end up damaging things: sand kicked up, increased, rapid water movement from folks finning, just lack of caution and care.

We ended up not taking people to that part of the reef to try and help it recover. It was pretty depressing though to see this amazing, big Gorgonian with 5-6 Bargibantis on it... and then a few months later a slightly ragged, sad looking fan in a bashed up area. Really sad. 

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1 hour ago, TimG said:

We ended up not taking people to that part of the reef to try and help it recover. It was pretty depressing though to see this amazing, big Gorgonian with 5-6 Bargibantis on it... and then a few months later a slightly ragged, sad looking fan in a bashed up area. Really sad. 

This is really sad to hear. I fear not so uncommon at frequented dive sites. As you say and also the cited study shows, this was not the work of strobe energy, but of careless and just too many people...

I also must add a sad anecdote: on my last diving trip in March to Raja Ampat I had to observe a dive guide, who was not just pointing to a pigmy sea horse with his rod, but used it to place it in right position for the photographer...:vava:

 

Wolfgang

 

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From personal experience id say even a low lumen constant light has MUCH more of an effect on marine life than a strobe.

Even something dim like a 3,000 lumen lots of marine life actively distances itself from you or turns away.  10,000+ is significantly worse.

With a strobe, although its much more powerful its over very quickly.  I suspect some animals simply dont even see the flash - theres no reaction at all (lionfish, bannerfish, barracuda etc).  Some clearly DO see it and blink (turtles octopus, cuttlefish etc) but do not turn away or try to leave the area.

I guess its like a person, take a photo of me with a camera flash its unlikely to annoy me.  But shine a really bright light constantly in my face and im far more likely to get annoyed or turn away.

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I certainly notice many fish will move on when I point my focus light at them, so I have taken to turning the light on only when I need it.   This light is rated at 700 lumens and has a 60°beam.  I am toying with going back to my older torch of 350 lumens - not much output you might say but it's certainly  more than adequate for focusing at macro distances when I'm under overhangs or in caves.  Shooting video of course is a different issue as you need much more light and a few more lumens helps penetrate poor viz and deeper into overhangs for focus and spotting lights. 

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https://www.nature.com/articles/s41598-018-37356-2

To be fair, when this paper was first referenced in the diving press, there were marine scientists who wrote to disagree with the results.

Also, its flash/strobe, not video lights.

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