[Coral-List] Parrotfish loss drives reef decline

Pedro M Alcolado gmalcolado at gmail.com
Fri Feb 10 15:34:59 EST 2017

Hi Eugene!
But parrotfishes munch on algae growing on the coral reef rocky
bottoms where coral recruitment takes place.
Best wishes,

On 2/10/17, Eugene Shinn <eugeneshinn at mail.usf.edu> wrote:
> One might wonder if the indigenous people of Panama had fishhooks
> 1000-500 years ago? And, were they able to affect parrotfish abundance
> enough to influence coral growth?Of all the many reef cores  drilled
> during the past few decades I can’t recall seeing Parrotfish
> teeth/beaks. It would take a good eye especially since cores recovered
> using these devices are biased toward larger corals. Most uncemented
> reef sand that could contain teeth and urchin spines is flushed out and
> lost during coring. Even if the article in Nature, “Parrotfish loss
> drives reef decline” is correctly interpreted one has to wonder if the
> conclusion is a “chicken-or-egg-which-came- first issue?” Cores from
> Florida reefs show they have suffered periods of non-growth during the
> Holocene and in fact cores and seismic profiling show long strips of the
> Florida reef tract where corals did not create a coral reef during the
> past 6,000 years. With all the sea fans, sea whips, sponges, and
> occasional large head corals that populate these non-reef areas it is
> easy for the average diver to think they are swimming over true coral
> reefs. In the early days of diving I certainly made that mistake.
> Whether periods of non-growth, and its causes in the past were the same
> as the non-growth we are seeing today is problematic. People in Florida,
> unlike citizens of Pacific islands, do not catch or legally eat
> Parrotfish. In Tahiti parrotfish are often the most expensive fish on
> the restaurant menu. Because we don’t eat them we still have an
> abundance of Parrotfish and Blue Tangs that munch the abundance of algae
> growing on our mostly dead corals. There is also no competition from
> algae eating /Diadema/, which disappeared from Florida reefs (in fact
> Caribbean wide) in 1983.
> By watching and listening  keys divers can always see and hear the
> munching of Parrot fish taking bites from dead coral to get at the
> attached algae. I suspect there are more Parrots feeding on our dead
> reefs than on live reefs because they do not munch on live coral. On the
> Florida reef tract one simply cannot find dead corals that lack
> distinctive crisscrossing beak and tooth marks. Our dead reef areas are
> literally being chewed away and defecated as reef sand.Any coral polyps
> that might recruit to these dead coral surfaces will likely be swallowed
> by roving munching bands of Parrotfish and gangs of Blue Tangs. One
> might wonder that if these coral munchers were removed would the growing
> corals come back? Of course something else killed them in the first
> place and that something needs to be solved. It is highly doubtful if
> reef cores could be used to determine which came first, death of corals
> or Parrotfish removal. Gene
> --
> No Rocks, No Water, No Ecosystem (EAS)
> ------------------------------------ -----------------------------------
> E. A. Shinn, Courtesy Professor
> University of South Florida
> College of Marine Science Room 221A
> 140 Seventh Avenue South
> St. Petersburg, FL 33701
> <eugeneshinn at mail.usf.edu>
> Tel 727 553-1158
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