Hybridization/phenotypic variation in Acropora

[Judy Lang/Lynton Land]

Dear Edwin, Pedro et al.,

In contrast to the situation described below by Edwin, there is--or at
least there used to be--a small reef  crest in a relatively sheltered
location inside Discovery Bay Harbour (SW corner, just west of the
bauxite loading facility) in which. if I remember correctly,  the outer
margins of some colonies of Acropora palmata produced a morphology more
resembling A. cervicornis than A. prolifera. I presumed this was a
response to reduced rates of water flow.

Judy

On Friday, February 14, 2003, at 10:45  PM, Hernandez Edwin wrote:

> Dear Pedro and fellow listers.
>
> Just a minor observation following Pedro's posting on
> rapidly changing Acropora palmata morphology.
>
> Here in Puerto Rico, I've seen in two locations on the
> northern coast at Arrecife La Ocho, also known as El
> Escambron (San Juan), and at Vega Baja Beach (about
> 20-25 km west of San Juan) high densities of A.
> palmata colonies with mixed phenotypes.
>
> These colonies are growing on very shallow (0.5-1.5 m)
> and highly turbulent habitats. Most of the colonies
> show typical A. palmata branches in the colony
> portions under less turbulent microhabitats (lower
> part of the colony). But, those colony portions
> exposed to the prevalent turbulent conditions (upper
> branches) show typical A. prolifera forms.
>
> I've always thought that these "hybrid" morphs are the
> result of local environmental factors. Their
> distribution is limited only to the most turbulent
> zone. Thus, it would be interesting to look at the
> genetics of these known A. prolifera hybrids and those
> A. prolifera-looklike palmatas.
>
> Is this sudden increase in branchiness a strategy to
> dissipate high energy from incoming waves? Or is it
> simply a reproductive strategy to rapidly colonize,
> disperse and dominate shallow turbulent reef zones? Or
> is it an strategy of some genetic variants to try to
> fix their genes by producing larger numbers of weaker
> fragments, which will inebitably will fragment and
> disperse, thus rapidly dispersing genetic clones
> downcurrent?
>
> Moreover, this process that Pedro just described under
> aquarium conditions, which might be the same one that
> could explain my observations under field conditions,
> should be tested as a potential A. palmata propagation
> and restoking method.
>
> If palmata branches can exhibit such a rapid increase
> in branchiness under stronger water movement, then,
> wouldn't it be feasable either to propagate corals
> under flowing tank or field conditions by allowing
> single branches to rapidly produce a high number of
> new branches which can be cut and transplanted to
> repeat the process?  Just a though...
>
> Cheers,
>
> Edwin
>
> =====
> Edwin A. Hernandez-Delgado, Ph.D.
> University of Puerto Rico
> Department of Biology
> Coral Reef Research Group
> P.O. Box 23360
> San Juan, P.R. 00931-3360
> Tel (787) 764-0000, x-4855; Fax (787) 764-2610
>
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