Reefs at Risk

[Bob Steneck]

Dear Thaddeus,

  I've been interested to learn the results of the 1995 Keyswide Coral 
Reef Expedition.  Your results spawned some questions that perhaps you 
can answer.

1.  How can patterns of decline be determined from a single survey?  Do 
you have a way of estimating the rate of coral mortality?

2.  Since percent cover of coral varies for many reasons (including 
morphogenetic reasons) how do you sort out reefs that always have had low 
cover from those that have declined to that level recently?

3.  Are you surprised at the low acroporid abundance at 20 m?  Most 
geologists who find Acropora palmata in their cores assume they grew 
between 10 m and the surface.  In St. Croix in 1973 we had about a 12 m 
depth max for that species.  Are you sure it's absence at 20 m now 
demonstrates "the powerful effects of region-wide disturbances such as 
disease?" (Don't get me wrong, I believe Acroporids have succumbed to 
disease throughout the region)

4.  Perhaps I don't understand your figure but wouldn't that pattern 
develop if massive spawners are the dominant corals at depths of 20 m.  
If that's so, wouldn't a similar figure be generated on just about every 
reef in the Caribbean?  Excuse me if I misunderstood what you meant.

  Sincerely,

  Bob Steneck   

----------------------------
Robert S. Steneck
Professor, School of Marine Sciences
University of Maine
Darling Marine Center
Walpole, ME 04573
207 - 563 - 3146
e-mail: Steneck at Maine.Maine.EDU
The School of Marine Sciences Web site:
http://www.ume.maine.edu/~marine/marine.html