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The exhilaration of being back in the maze of these exquisite islands and of gliding over corals among clouds of fishes is enough for now, and I simply just enjoy it. Curiosity gets the best of me in time and the imperative to be observant and record my observations takes over.

Patterns soon emerge to tell a story of corals surviving or succumbing to stress and bleaching from warmer than normal seawater.  The first hint of these patterns emerged when I traveled to Palau in 1999 during my first year working with The Nature Conservancy. Diving on this most recent trip, as my eyes adjusted to the deep shade under an eroded overhang of the mushroom shaped limestone islands, I recalled that first trip again. Here the corals were alive, dark in color, apparently healthy, and contrasted sharply with their bleached or dead counterparts on the sun drenched reef nearby.

A mosaic of the shallow reefs stretching in a patchwork of color that is dissected by the blues and greens of deeper water fringes the Rock Islands. Here, too, I was taken aback - the shallow corals on reef tops that were exposed directly to air, sun and rain at low tides and which we might expect to be more affected by hot seawater, were alive and well. The deeper corals down the reef slopes were largely dead. Baffling.

From the Rock Islands we set off north where the Conservancy has helped the Kayangel State community to set aside the entire Ngeruangel Atoll as a reserve. But first a stop in Ngeremeduu  Bay and the barrier reef offshore. There were more surprises in store. Corals in the shallow, warm, silty waters of the bay (the largest estuary in Micronesia) were few and far between, but alive and healthy. At the mouth of the bay where the water was clearer, corals were well developed, diverse, and scarcely affected by bleaching. While on the offshore barrier reef, where the water is so clear as to be almost transparent, the corals were essentially all dead.

Suddenly things fell into place. Heated seawater stresses the corals and causes them to bleach. Light seems to finish them off.  So the deeply shaded corals in the Rock Islands and those in Ngeremeduu Bay that are screened from harmful light by silty water were able to survive, as were the stress-tolerant corals on reef tops. After bleaching, corals that normally thrive in crystal clear waters were vulnerable to the harmful effects of light, and succumbed.

As a postscript, our simple observations on bleaching resistance in Palau have led to the mandate for us to build a worldwide program on coral reef conservation that is founded on the concept of resilience in the face of change. Global leaders from around the world have helped us to plan this program. It is fitting that Palau emerged from this process as the highest priority area for establishment of a nationwide network of marine protected areas built on the resilience principles that had their origins there.

 

About Dr. Rod Salm, The Nature Conservancy:
Dr. Rod Salm is currently Director, Coastal Marine Conservation , for TNC's Asia Pacific and California Division. Raised in Mozambique, Rod has spent most of his professional life in East Africa and the Western Indian Ocean and Asia, where he has more than 25 years experience in conservation of coastal and marine ecosystems. He has also worked in parts of Latin America and the Caribbean and in polar environments. Rod has published more than 170 articles and 6 books on marine ecology, taxonomy, resource management, conservation, and popular natural history.
 

Rod Salm
Director, Coastal Marine Conservation
Asia Pacific and California Division, The Nature Conservancy