I have a new BB 9780 and I was trying to search through the options and settings to see if there was a way to adjust the transparency on the "bars" at the top and bottom of the Home Screen.

The bars are a lot darker than on my old Curve and basically obscure the top and bottom thirds of whatever wallpaper image I choose.

Is there a way to increase the transparency?

No, that's not an adjustable setting.
You'd need to find (or make) a new theme that has it pre-set to your liking.