Meeting Abstract

85.4  Friday, Jan. 6  Digital Reef Rugosity DUSTAN, P.*; DOHERTY, O.; PARDEDE, S. T.; VANCE, J.; COWAN, N. J.; College of Charleston, Charleston SC; Biosphere Foundation, Big Pine CA; WIldlife Conservation Society, Bogor Indonesia; College of Charleston, Charleston SC; Johns Hopkins University, Baltimore MD

Habitats with greater structural complexity contain more species due to increased niche diversity. This is especially apparent on coral reefs where individual coral colonies aggregate to give a reef its morphology, species zonation, and three dimensionality. Reef rugosity classically describes this complexity as the ratio of a straight line transect to the distance a flexible chain of equal length travels when draped along the reef. Variants of this technique including visual categories, small scale measurements, acoustic backscatter, raster satellite imagery and aerial-based lidar have characterized reef rugosity at scales ranging from microhabitats to kilometers. In most cases a positive relationship exists between fish community distribution and estimates of rugosity.

In this communication we describe a new simple digital technique to estimate reef rugosity. Digital Reef Rugosity (DRR) enables a diver to quickly, easily, and accurately measure reef topographical complexity at the centimeter scale along meter scale transects. Our data demonstrate a positive relationship between DRR and fish diversity across a number of different habitats on shallow water Balinese coral reefs and reinforce the concept that habitat complexity is a fundamental property of reef communities.

The power of DRR lies in its precision and ability to easily record digital data applicable to analysis and modeling. Since changes in the physical structure are reflections of population dynamics, DRR may become a useful quantitative community-level descriptor to explore the formation of ecological tipping points as coral reefs degrade into carbonate rubble and cease to support their fish populations.