[Coral-List] The myth of 100% coral cover

Dean Jacobson atolldino at yahoo.com
Sun Mar 18 02:17:55 EDT 2012


I have a creeping/sinking baseline question.

On the coral-free-for-all, there was a comment that 100% coral cover is very rare, supported with a quote from a Veron email to the effect that "there is no reason why coral would so dominate the substrate"  In other words, total, 100% coral cover is a myth.  My experience is limited to a very few regions (Puerto Galera on Mindoro, where soft coral and crinoids dominate, and Palau and Maui), in addition to my home in the RMI.  My visits over the past decade to a dozen Marshallese atolls have convinced me that over 50% live cover is typical, on average (actually closer to 75%) and some reefs, such as along the southern shore of Rongelap Rongelap, 95-100% coral cover is the average for many hundreds of meters, excluding the deep, narrow grooves or canyons.  The reason for this, I would assume, is high recruitment, clean water and very limited disturbance/mortality (there has been an extremely low human presence on this atoll for several decades, due to
 fallout from the Bikini atoll Bravo H-bomb test).  

Such high coral covers appear to be rule in much of the Marshalls where storm damage, fatal bleaching, COTS outbreaks and human-associated pollution is minimal.

There are exceptions, such as Ebon's COTS-devastated lagoon, and Likiep atoll. where, i.e. in the South Pass, Microdictyon algae grows profusely, possibly due to upwelling nutrients; this green algae has vanished on Majuro in proximity to human settlement, it is clearly intolerant to pollution.   I have hundreds of images that document 100% coral cover in the RMI, and Zoe Richards has Rongelap survey data as well.

My question, in the global context, is the RMI an anomaly, in your experience?

Dean Jacobson
College of the Marshall Islands

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