[Coral-List] Do corals need fish to remain healthy?

Eugene Shinn eshinn at marine.usf.edu
Fri Feb 20 09:53:51 EST 2009

Bill Precht, Program Manager at the Florida Keys National Marine 
Sanctuary  recently made me aware of a new paper titled, "Macroalgae 
Has No Effect on the Severity and Dynamics of Caribbean Yellow Band 
Disease." Ivana Vu et. al, 2009, published in PloS Feb 09 Vol 4 Issue 
2. The paper is the result of an ingenious  manipulative field study 
in Puerto Rico. As the title implies it shows, that various 
Macroalgae have no effect on CYBD in Montastraea faveolata . This 
conclusion contradicts the widely repeated mantra that these algae 
stimulate coral disease by serving as a reservoirs of pathogens  and 
that their proliferation on reefs is due to removal of herbivorous 
fishes. In other words, remove fish (overfishing) that eat algae and 
the algae will grow and cause decline of coral.
When I read the paper I was reminded of a recent conversation with 
Harold Hudson of Reef Tech  who described to me what he recently saw 
in Roatan. "It was the biggest healthiest staghorn coral forest I 
have seen in many years", he said.  What caught his eye also was that 
there were essentially no fish! Not even the ubiquitous Damsel fish 
that normally thrive among staghorn branches. It was wonderful to 
hear that such healthy staghorn fields still exist but isn't it odd 
that it is thriving  without the usual tropicals, surgeon, and parrot 
fish? Similar observations have been recorded by J. Keck et al., 
"Unexpectedly high cover of Acropora cervicornis on offshore reefs in 
Rotan (Honduras)" published in Coral Reefs, DOI 
10.1007/s00338-005-0502-6  and also confirmed in a paper by B. Riegl 
et al, Offshore refuge and metapopulation resilience explains high 
local densisty of an endangered coral (Acropora cervicornis). In 
Marine Pollution Bulletin.  Many of us can remember the luxurious 
corals on the North coast of Jamaica before the early 1980s at a time 
when the area had already been fished out. Apparently what ever 
started the general Caribbean decline in the late 1970s and early 
1980s remains  somewhat elusive but widespread.  I suggest we need 
more straight-forward in-the-field experiments such as the Puerto 
Rico study cited at the beginning.  May be we should  rethink the 
commonly cited association between fishing and coral health??  Gene

No Rocks, No Water, No Ecosystem (EAS)
------------------------------------ -----------------------------------
E. A. Shinn, Courtesy Professor
University of South Florida
Marine Science Center (room 204)
140 Seventh Avenue South
St. Petersburg, FL 33701
<eshinn at marine.usf.edu>
Tel 727 553-1158---------------------------------- 

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