Ecological 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. Structural complexity is classically measured with a reef rugosity index, which is the ratio of a straight line transect to the distance a flexible chain of equal length travels when draped over the reef substrate; yet, other techniques from visual categories to remote sensing have been used to characterize structural complexity at scales from microhabitats to reefscapes. Reef-scale methods either lack quantitative precision or are too time consuming to be routinely practical, while remotely sensed indices are mismatched to the finer scale morphology of coral colonies and reef habitats. In this communication a new digital technique, Digital Reef Rugosity (DRR) is described which utilizes a self-contained water level gauge enabling a diver to quickly and accurately characterize rugosity with non-invasive millimeter scale measurements of coral reef surface height at decimeter intervals along meter scale transects. The precise measurements require very little post-processing and are easily imported into a spreadsheet for statistical analyses and modeling. To assess its applicability we investigated the relationship between DRR and fish community structure at four coral reef sites on Menjangan Island off the northwest corner of Bali, Indonesia and one on mainland Bali to the west of Menjangan Island; our findings show a positive relationship between DRR and fish diversity. Since structural complexity drives key ecological processes on coral reefs, we consider that DRR may become a useful quantitative community-level descriptor to characterize reef complexity.

Quantitative and qualitative surveys in November-to-December 2004 revealed near 100% coral mortality in the lagoon of Kanton Atoll and 62% mortality on the outer leeward reef slopes of this island as well as elsewhere throughout the Kiribati Phoenix islands in the Central equatorial Pacific Ocean. most dead colonies were in growth position. Colonies were encrusted with coralline algae indicating they had been dead for 1 to 2 years, thus dying just after an expedition by the New england Aquarium in July 2002 which declared the region one of the most pristine reefs left in the Central Pacific.Fish populations did not seem reduced to the same levels as the stony corals but only 153 species of fish were identified at the study sites. Apex predators and key indicator fish species were present suggesting little impact from overfishing. Populations of invertebrates, now dominated by sponges, were also seemingly reduced inside the Kanton Atoll lagoon. Thirty-six species of living corals were identified along 480 m 2 of transects. Five of eight coral genera represented <1% of the bottom cover. many of the living corals found were less than 10 cm in diameter suggesting recruitment has occurred since the mass mortality.bleaching Hot Spot Analysis by National Oceanographic and Atmospheric Administration / National environmental Satellite, Data, and information Service (NOAA/NeSDiS) satellite monitoring revealed a record high of 16 degree heating weeks (DHW) around the Phoenix islands between August 2002 and march 2003. The Kanton Atoll lagoon has a residence time approaching 50 days, there is no significant source of land-based pollution and there was no sign of any destructive fishing practices. Hence, the exposure to excessively high water temperatures for over six months killed the coralreef community of Kanton Atoll lagoon and caused the excessive loss of coral species and cover throughout the Phoenix island group. These observations provide further evidence that coral reefs in the most remote part of the Central Pacific Ocean are not isolated from the effects of global warming.

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