Golbuu, Y., Victor, S., Penland, L., Idip, D., Emaurois, C., Okaji, K., . . . Woesik, R. V. (2007). Palau’s coral reefs show differential habitat recovery following the 1998-bleaching event. Coral Reefs,26(2), 319-332. doi:10.1007/s00338-007-0200-7
Golbuu et al. examine coral species variation, recruitment, and recovery rates in Palau, Micronesia following a dramatic bleaching event in 1998. Coral bleaching is a significant threat to coral diversity and is ultimately caused by rising ocean temperatures. The authors express that it is necessary to assess these Palauan reefs to make predictions on how corals can respond to climate change in the future.
The authors examined 13 permanent study sites of varying reef habitat types in 2001, 2002, and 2004 using digital-video analysis and random transect sampling to define the presence and abundance of coral recruits. Statistical tests were used to determine significant differences in coral recruitment and cover of common coral species over time and at different habitat types and depths.
The amount of coral present increased over time in the more sheltered bays (e.g. Nikko Bay), and they supported significantly different colonies of corals than the reefs being exposed to more wave action. The more exposed reefs had high levels of new colony formation (recruitment). Therefore, Palau’s coral reefs can recover rapidly from disturbance because they’re either protected from the disturbance itself or establishing new coral colonies from larvae that came from those protected reefs.
Significance for Palau:
The authors of this study concluded that Palau’s coral reefs exhibited remarkable recovery rates after the bleaching event in 1998. In fact, several coral reefs in Palau have demonstrated an observable resistance to bleaching – either due to their toughness, their resilience, or their environment. Nikko Bay is an especially interesting reef in the context of coral bleaching resistance. Its waters are highly acidic due to a combination of coral respiration, coral skeleton formation, and lack of water movement. This extreme climate has made the corals better adapted to dramatic changes in environmental conditions. Furthermore, reefs off the rock islands can also effectively resist bleaching due to the shade given off from the islands themselves. This shading results in lower temperatures and can keep the coral alive. If these resistant reefs are protected from anthropogenic threats, they could be the key to preserving Palau’s coral species.