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Sunning darters?


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#1 Guest_FirstChAoS_*

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Posted 19 August 2014 - 12:41 AM

Sunday I went to a river (sadly cannot post pics until I fix/repair my monitor) and was surprised to see a group of tesselate darters just sitting on the bottom, out in the open, in a sunny spot. This made me wonder, will darters sun themselves to warm up? A few of them did swim up to investigate my feet when I approached.

#2 Guest_Uland_*

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Posted 19 August 2014 - 06:52 AM

Perhaps I'm wrong, but try to change your body temperature while immersed in a flowing body of water seems futile. Now sitting under a pile of dark leaves in a protected inlet seems like a great way to warm up.

#3 Michael Wolfe

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Posted 19 August 2014 - 08:06 AM

I have noticed that I often find more shiners under sunny spots. But I always assumed that it was maybe because that's where there are more gnats and other bugs in those sunny spots. Bugs that might fall in the water and be shiner food. I seem to remember some studies that indicate that many fishes eat more terrestrial insects than they do aquatic.
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#4 Guest_centrarchid_*

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Posted 19 August 2014 - 09:49 AM

Spots could be locations where eats more abundant. Need to determine if temperature different than alternative areas. Could even be cooler if spring upwelling. During cool season my bluegill will hang near surface and get dark like a bullfrog which might enable them to cheat up a degree or two to speed digestion.

#5 Guest_Skipjack_*

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Posted 19 August 2014 - 05:11 PM

I can say that gar are the only fish I can think of that obviously seem to bask in sunny spots at the top of the water. Even in flowing water.

#6 Guest_centrarchid_*

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Posted 19 August 2014 - 06:44 PM

I can feel heat coming from sunlight when in shallow water so fish likely similarly capable but does it make a difference. They might also me doing a little photosynthesis to make vitamins.

#7 Guest_fundulus_*

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Posted 19 August 2014 - 07:41 PM

That's an interesting thought, I realize I have no clue if fish can synthesize their own vitamin D or get enough from diet. Since many (most?) fish live at depths where light intensity is attenuated I'd have to think that the ability is hugely variable at best.

#8 Guest_Skipjack_*

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Posted 19 August 2014 - 08:46 PM

I have seen what Josh described. Slackwater darters hanging in sunlit pockets. I figured it had more to do with light attracting prey, but I am sure that even in flowing water that sunlight can warm to an extent as radiant heat. As Uland said he can not imagine it, nor can I, but we are warm blooded. Fishes may feel the tiniest differences.

#9 Isaac Szabo

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Posted 19 August 2014 - 11:07 PM

Yes, a fish in direct sunlight will be warmer than a fish in shade, even though the water temperature may be the same. A percentage of the direct sunlight reaching the fish will be converted into heat, warming the fish. It's really no different than why being in direct sunlight on land is warmer than being in shade, even though the air temperature is the same. When snorkeling in chilly water, I certainly notice the temperature difference between direct sunlight and shade as well as when a cloud passes in front of the sun. I have no idea to what extent fish use this to thermoregulate. I can't say I've ever really noticed more fish in the sunny spots, but it sounds like others have. If so, there could be other factors at play as well (like food). It could be an interesting area of study.

#10 Guest_gzeiger_*

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Posted 19 August 2014 - 11:39 PM

Could be it's easier to spot certain predators that would cast a shadow?

#11 Guest_don212_*

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Posted 20 August 2014 - 08:05 PM

water temps will rise a little, along with radiant warming

#12 Guest_FirstChAoS_*

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Posted 21 August 2014 - 02:07 AM

got a new monitor, uploaded the darters in the sun (and curious about my feet).

their were more of them out of the video frame, and the one in front of my flipper didn't show up in the video,

https://www.youtube....h?v=ii4XTo1qLRQ

https://www.youtube....h?v=es4LSWrrD1I




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