From what I have experienced, it seems that the black crappie definately thrive better in clearer water lakes with lots of vegetation. The black crappie will tend to hold to cover all of the time...unlike the white crappie who tends to roam and suspend more. Look deep in brushpiles to catch black crappie. Once you find 'em, you will be in love with the black crappie. They get some shoulders on them. I caught a 3lb black crappie back in December, and he was only 16.5" long. A white crappie of the same length wouldn't have even come close to that mark.
Another tactic that was useful to me a few months ago in a lake here in AR...14' deep with hydrilla growing up to within 5' of the surface...spider riggin over the top of the grass. It seems that the black crappie were hiding in the grass and would ambush baitfish sitting on top of the grass. The only thing about this lake is that there is lots of standing timber. So, the black crappie still had wood cover to go along with the vegetation cover. It may be worth a try in your neck of the woods.