Coral starving and survival

[alcolado at ama.cu]

Dear Lance,,
Thanks for your reply. Acropora palmata has coevolved with
hurricanes and indeed is one of the most addapted species to
those events. Furthermore, there has not been an apparent change
in  hurricane regime trends at least in Cuba.
I am not talking about what is happening in zooplankton in the
Caribbean or globat tropical region, I am only comparing corals
exposed to different amounts of plankton availability at local scale.
The hypothesis (not  a conclussion)  is that inshore corals could be
 better fed (more zooplankton)  than  windward ocean exposed
ones  (less zooplankton available)  and so, possibly less prone to
be  affected by mortality agents.  In other words, I am not talking
about  any trend of zooplankton in the Caribbean region, that
maybe is  like the way you say (increasing?), but maybe not  if you
consider  that the probable lesser level of spawning (because of
overfishing)  could be conducting to lower zooplaknton
concentrations, given the  possible lesser amounts of eggs, larvae
and juvenile. It is really  an aspect very needed of research. It is
interesting to point aout that zooplankton concentrations are
decreasing in north cold latitudes (after comments I heard in this
coral lists just in discussions about  MacKenzie's hypothesis).
All the best,
Pedro


From:                   "Lance K.B. Jordan" <JordanL at nova.edu>
To:                     <alcolado at ama.cu>
Subject:                RE: Coral starving  and survival
Date sent:              Fri, 8 Mar 2002 14:10:55 -0500

> Dear Pedro,
>
> I am not a coral expert, nor claim to be.  But what you described
is
> typical throughout the Caribbean.  I have read that hurricanes
have
> dictated the demise of A. palmata.  Usually the main energy of
hurricanes
> occurs on the windward and exposed side of the island, hence
the dead
> palmata on the oligotrophic (clear water) side of the islands.
This, in
> my opinion, is a much more logical explanation than starvation.
>
> Corals are zooplanktivores.  Zooplankton eat phytoplankton.
Phytoplankton
> need sunlight and nutrients to subsist.  Humans have likely
increased the
> amount of nutrients in the world's oceans in addition to
overexploiting
> fisheries.  Many fishes are zooplanktivore. So, not only have
humans
> increase the food source of zooplankton (by increasing the
nutrient
> concentrations which, in turn, increased phytoplankton
populations) but
> humans have decreased the number of possible zooplankton
predators.
> Therefore, it is highly probable that, rather than the idea that the
> ocean's are starving, zooplankton concentrations have increased
in recent
> years.
>
> Your reply is welcome.
>
> Lance Jordan
>
>
>
> -----Original Message-----
> From: owner-coral-list at coral.aoml.noaa.gov
> [mailto:owner-coral-list at coral.aoml.noaa.gov]On Behalf Of
> alcolado at ama.cu
> Sent: Friday, March 08, 2002 1:16 PM
> To: coral-list at aoml.noaa.gov
> Cc: debimack at auracom.com
> Subject: Coral starving and survival
>
>
>
> Dear coral-lister,
> I decided to add a little more firewood to discussion on Debbie
> McKenzie's interesting coral starving-survival hypohesis.
> During an AGRRA assessment along the south and east of  the
> Gulf of Batabano (SW Cuba; march 2001) the Cuban-
International
> team observed a  gradient of improving condition in Acropora
> palmata (from a situation where practically all colonies were dead
> along the south) in the extent we approximate to the huge Zapata
> swamp (which is supposed to enhance plankton productivity and
> where water becomes greenish and more turbid). The two
Acropora
>  palmata  crests closest to Zapata swamp looked practically
> healthy.
> Another Cuban-International AGRRA assessment in the
> Archipelago Jardines de la Reina (SE Cuba) showed that
Acropora
> palmata in the windward crests of Cayo Caballones, exposed to
> the oligotrophic ocean were virtually dead, while a small Acropora
> palmata crest located leeward of the same key and exposed to
the
>  most biological productive shelf of Cuba (varying from
mesotrophic
> to eutrophic along a cross gradient towards mainland) was alive
> and really beautiful (mixed with dense thickets of live Acropora
> prolifera).
> Probably well fed Acropora palmata crests survived the massive
> mortality event(s) (cause unknown: coral bleaching, white band,
> patchy necrosis?) that killed the crests exposed to less nutrified
> and less productive oceanic waters.
> If so, McKenzie’s hypothesis, far from be discarded prematurely,
> has to be tested because it could explain differences in the fate
of
> some coral reefs at small scale, and also explain some
> mismatches at larger scale when correlating coral bleaching with
> sea surface temperature.
> I fully agree that higher sea surface temperatures are the primary
> cause of coral bleaching, but the fate of corals ususally is
> conditioned by other complementary factors (cloudiness, sea
> surface roughness, water transparency, etc.), very probably
> included the degree of coral starvation.
> Cheers,
> Pedro M. Alcolado
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