Elmotrack

I've experienced these little bugs. They're little flies or silverfish or springtails. (even though they don't really seem to fly) They likely come from eggs dormant in the bark or were attracted to the food, but likely the bark.

If you have any live plants in soil, they could have come from that and gotten into your turtle enclosure. They could also grow in the turtle poo too.

They are a bugger of a thing to get rid of.

However, just to make sure, take a close look at one of those bugs to make sure it's not a mite or a tick. Reptiles are prone to those. Type mite or tick into a search engine for an image of one. If it is mites or ticks, which from the sound, I highly doubt, but if so, you'll have to clean the tank top to bottom, change everything inside, and you'll need to get a treatment solution from your petstore. But again, it doesn't sound like that's the problem, so there's really not an actual harm to the turtles.

If the conditions are too moist in the bark, this is what helps these buggers (the flies) multiply.

But no they won't really harm your turtle.
They're just annoying and they are hard to get rid of.

It'll take a thorough cleaning. Remove and (replace with new) all plant material too, including any branches and bark. Thoroughly disinfect the water dish, top and bottom.

You might consider using moss or sand as a substrate. They absorb moisture better and keep in humidity.
I actually like the pine fresh cat litter too. Some turtles are stinky. However, if you mist your turtles' tank all over, pine fresh would not work well. If you don't mist, and just use a water dish, then pine fresh would be very easy and very absorbent for turtle waste.
Those indoor-outdoor green carpets are good too, and easy to keep clean. Cut a few pieces to fit, and exchange them out when you clean the tank. Clean the carpet and put it back in rotation. And they'll be better with moisture.

Or, you could add a small lizard or tree frog and let them have at those pesky bugs. But really, even a hundred frogs won't put a dent in those bugs.

And lastly on those little flies, they will get out of your turtle tank and infest the rest of your house if you have live plants, or have any kind of organic matter outside of the fridge, ie… potatoes, fruit, etc…. So, cleaning the turtle tank pronto will help keep them from spreading.