A novel approach to measuring subtidal habitat complexity

Habitat complexity plays an important role in determining benthic community structure. A diverse range of methods for its measurement have been adopted but none are convenient for use underwater where access time is at a premium. We describe a novel, calibrated, tool for rapidly measuring scale-dependent habitat complexity developed, primarily, for use underwater. This tool is based on a distance-wheel with interchangeable wheels of different sizes to allow a scale-dependent measure of distance. This technique was calibrated against a profile of known complexity, at relevant scales, and then trialed on the Loch Linnhe Artificial Reef, a replicated artificial substratum offering two different scale-dependent habitat complexities. The distance-wheel was cost-effective, simple to fabricate and enabled the rapid and straightforward measurement of perceived distance over the step-length range of 133-1020 mm.