Hopefully my comment is not too far off track from the original post, but when reading this (above) I thought I'd jump in. In terms of dissolved oxygen, the O2 levels are greatly dependent on sunlight penetration, are they not? If you have murky water, for example, and its summer time- sunlight will only penetrate the first few feet of water, so photosynthesis is limited to that space, and the thermocline should also be pulled up closer to the surface due to limited light penetration, true?
And, if bass rarely go below the thermocline (baitfish feed on plankton and other things that depend on the sunlight & photosynthesis, better O2 levels, visiblity issues, etc) then, at least in quite stained water, should this not position bass fairly shallow 'naturally' as a consequence?
You factor in wind, sprng water, streams, creeks and rivers. Moving water via wave action or tumbling over rocks etc., oxygenates the upper water column. Sun light drives photosynthesis, however aquatic plants consum Do during the night. The water would need to be very dirty to reflect sun light penetration to a few feet, most off color water will still have a depth of light about 5 to 6 feet.
If the alke doesn't have deeper water, a lot of low land and natural lakes in Florida for example, restrict the bass from finding deeper water and must adapt to the water they live in. The bass in shallow lakes use heavy weed mates that provide shade that cools the water under them a few degrees. The bass will still seek the coolest water possible, under hot water conditions. If the wind stops and the heat continues to over heat the water, the bass will die off from lack of DO.
Threadfin shad eat phyto planton, gizzard shad and some other baitfish eat zoo plankton, vegetable verese animal. Most baitfish eat small water or airborne creatures that live in or near the weed cover.
The one constant that you can depend on is; bass will not be far from prey.
The thermocline (metalimnion) is located where the upper layer cools about 3 to 4 degrees within a few feet, in most lakes. The idea that lakes only have one thermocline and no DO below that layer can be miss leading. Lakes that have current can and do have multiple thermocline layers with sufficent DO level between. The lowest layer (hypolimnion) will be void of DO.
Where I fish the lakes often have 2 or more thermocline layers and bass populations living at those different depths. It's not uncommon for bass to be at 60 feet and 30 feet, moving up to spawn and at night. Like the shallow bass in Florida, the same bass have adapted to the ecosystem.
I think we are drifting way off topic.
WRB