[Coral-List] top-down, bottom-up

[Ilsa B Kuffner]

Dear Colleagues,

Relevant to the top-down, bottom-up discussion, we would like to bring 
your attention to a newly published paper concerning coral-algal 
interactions:

Kuffner IB, Walters LJ, Becerro MA, Paul VJ, Ritson-Williams R, Beach KS 
(2006) Inhibition of coral recruitment by macroalgae and cyanobacteria. 
Marine Ecology Progress Series 323: 107-117

If you wish to see the the full pdf file, it is available on the Mar Ecol 
Prog Ser website for free as an open-access article.  Simply go to:

http://www.int-res.com/abstracts/meps/v323/

and scroll down to our paper for easy downloading.  Here is the abstract:

Coral recruitment is a key process in the maintenance and recovery of 
coral reef ecosystems. While intense competition between coral and algae 
is often assumed on reefs that have undergone phase shifts from coral to 
algal dominance, data examining the competitive interactions involved, 
particularly during the larval and immediate post-settlement stage, are 
scarce. Using a series of field and outdoor seawater table experiments, we 
tested the hypothesis that common species of macroalgae and cyanobacteria 
inhibit coral recruitment. We examined the effects of Lyngbya spp., 
Dictyota spp., Lobophora variegata (J. V. Lamouroux) Womersley, and 
Chondrophycus poiteaui (J. V. Lamouroux) Nam (formerly Laurencia poiteaui) 
on the recruitment success of Porites astreoides larvae. All species but 
C. poiteaui caused either recruitment inhibition or avoidance behavior in 
P. astreoides larvae, while L. confervoides and D. menstrualis 
significantly increased mortality rates of P. astreoides recruits. We also 
tested the effect of some of these macrophytes on larvae of the gorgonian 
octocoral Briareum asbestinum. Exposure to Lyngbya majuscula reduced 
survival and recruitment in the octocoral larvae. Our results provide 
evidence that algae and cyanobacteria use tactics beyond space occupation 
to inhibit coral recruitment. On reefs experiencing phase shifts or 
temporary algal blooms, the restocking of adult coral populations may be 
slowed due to recruitment inhibition, thereby perpetuating reduced coral 
cover and limiting coral community recovery.

Sincerely, Ilsa Kuffner and co-authors

Ilsa B. Kuffner, Ph.D.
US Geological Survey
Florida Integrated Science Center
600 4th Street South
St. Petersburg, FL 33701