Purports to develop a multiscale model to measure "the refuge effect" of a marine reserve by analyzing conditions in a relatively pristine marine reserve to compare with less pristine nearby marine park environments. Uses the Tortugas Ecological Reserve within Dry Tortugas National Park (Fla.) as a case study to demonstrate these components of a refuge effect assessment: improved habitat characterization, determination of biological boundaries, and effectiveness of a large MPA in supporting ecosystem recovery.