Investigating fragment size for culturing reef-building corals (Porites lobata and P. compressa) in ex situ nurseries

Zac H. Forsman, Baruch Rinkevich, Cynthia L. Hunter

Research output: Contribution to journalArticlepeer-review


Culturing small propagules of coral has the potential for high yield with low environmental impact, provided that mortality is low. This study investigated the size-specific mortality and growth of minute fragments (as small as 5 polyps) of two of the most abundant reef-building corals in Hawaii (Porites lobata and P. compressa). Two ex situ nursery systems differing in cost, design complexity, and labor intensity were compared. The first nursery experiment lasted for four months in a large tank with high water motion/surge and extensive manual cleaning to remove competitive algae. The corals were then transferred to a simple low-flow tank containing sea urchins (Tripneustes gratilla) and reduced cleaning, where they were grown for six more months (Nursery II). 'Nursery I' resulted in 92% of P. lobata and 73% of P. compressa fragments surviving and nearly doubling in area, in spite of a brief infestation by a nudibranch (Phestilla sibogae) that primarily fed on larger P. compressa fragments. There was a significant positive relationship between fragment size and growth rate, and survivorship was significantly different between donor colonies (genets), but there was no evidence of size-specific mortality. 'Nursery II' on the other hand had clear size-specific mortality and higher urchin damage for smaller fragments, resulting in moderate survivorship (78% for P. lobata and 76% for P. compressa), and only a slight increase in the total area covered by coral tissue. Fragments larger than 3 cm2 were undamaged and had the highest survival and growth rates. This study illustrates how size-specific mortality can be reduced by ex situ nursery conditions.

Original languageEnglish
Pages (from-to)89-97
Number of pages9
Issue number1
StatePublished - 16 Nov 2006
Externally publishedYes

Bibliographical note

Funding Information:
We would like to thank four anonymous reviewers for their attention to detail and improvements on earlier drafts of this manuscript. We thank the Waikiki Aquarium staff, with special thanks to J. Charles Delbeek for designing the culturing tanks and providing excellent advice, to Mike Callahan for extensive assistance in building the culturing system, and to Norton Chan, Allen Nelson, Kelly Lam, and Jerry Crow for providing support. Thanks to Nadiera Sukhraj for assistance with coral culturing and to Lauren Ho and Sonoko Sakurai for assistance with data collection. This work was supported by the U.S.–Israel Bi-national Agricultural Research and Development (BARD) grant to C.L.H, and B.R.. Z.H.F. was supported by the BARD and a grant from the Hawaiian Coral Reef Initiative.


  • Coral aquaculture
  • Coral growth rates
  • Ex situ coral nursery
  • Porites
  • Size-specific mortality

ASJC Scopus subject areas

  • Aquatic Science


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