Higher Coral Density Can Increase Growth Despite More Predators

Researchers tested how coral colony density and predators affect coral growth by creating experimental reefs in a lagoon and found that both higher coral density and predator exclusion significantly boosted growth rates. Researchers placed concrete blocks in a lagoon to create experimental reefs, transplanted small Porites coral colonies at two different densities (2 vs 8 colonies per reef), used cages to exclude predators from half the reefs, and measured coral growth over 23 days. Predator exclusion increased coral growth by 20%. Higher coral density (8 vs. 2 colonies) increased growth by 30%. The effects of density and predation were independent; they didn't interact with each other. Higher coral densities attracted significantly more predators, but this didn't reduce the growth benefits. The research shows that coral colonies benefit from living in groups, which could inform coral restoration strategies and help predict how coral populations might respond to changes in reef density and predator communities.

Citation

Shantz, A. A.; Stier, A. C.; Idjadi, J. A. (2011). Coral density and predation affect growth of a reef-building coral. Coral Reefs.

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