RWD vs Sparisoma

Ron Hill Ron.Hill at
Fri Sep 26 09:34:16 EDT 1997


     I would also like to add some of my own observations into this complex 
     problem (debate) although I have just joined the list-server in the 
     last few days and have not been able to follow the entire debate thus 
     far.  While in Puerto Rico (over the last 3-4 years), I also witnessed 
     the chewing of corals by parrotfish (S. viride), as discussed by Jaime 
     Garzon-Ferriera from Columbia. Although the most common occurences I 
     noted were in the shallow forereef crest and the coral species was 
     Acropora palmata.  The parrotfish chewed a horizontal strip along the 
     edge of the "branch" about 2-3 cm deep into the skeleton, 5 cm across, 
     and often the entire length of the branch (maybe 50 cm long) on 
     horizontal branches.  Another graduate student at UPR told me that 
     this was caused by parrotfish when I initially saw it.  I argued with 
     him for more than 6 months, thinking he was sadly mistaken, until I 
     saw it happening myself.

     I understand that RWD was seen to continue to eat away at the corals 
     after they had been transferred to buckets, was there any evidence 
     that this disease could infect either healthy or physically damaged 
     corals in the bucket, or could spread to healthy areas of the infected 
     coral (by jumping over heathy tissue)?  Is there a change in pH under 
     the diseased area, by any chance?  This is not uncommon under biofilms 
     in pipelines where the local environment is set up and protected by 
     the biofilm or mucus of bacteria even in very fast flowing systems.

     Keep up the flow,

     Ron Hill (recently of UPR-Mayaguez)
     Sea Grant Fellow
     National Marine Fisheries Service
     Office of Habitat Conservation

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