Direct seeding of mass-cultured coral larvae is not an effective option for reef rehabilitation
Edwards, Alasdair J.
Guest, James R.
Heyward, Andrew J.
Villanueva, Ronald D.
Baria, Ma. Vanessa
Bollozos, Iris S. F.
Date of Issue2015
Nanyang Environment and Water Research Institute
Advanced Environmental Biotechnology Centre (AEBC)
Large-scale rearing of coral larvae during mass spawning events and subsequent direct introduction of competent larvae onto denuded reefs (‘larval seeding’) has been proposed as a low-tech and affordable way of enhancing coral settlement and hence recovery of degraded reefs. While some studies have shown positive short-term effects on settlement, to date, none have examined the long-term effects of larval seeding for a broadcast-spawning coral. Here, we test whether larval seeding significantly increases coral recruitment rates both in the short (5 wk) and longer (~6 mo to 1 yr) term. Larvae of Acropora digitifera were reared ex situ, and ~1 million larvae were introduced to 7 artificial reefs (ARs) while 7 others were left unseeded. Settlement tiles deployed on both seeded and control ARs were retrieved for examination 5 and 30 wk after seeding. In addition, the presence of visible coral recruits on the AR surfaces was monitored before and for ~13 mo post-seeding. Density of acroporid spat was significantly higher on seeded tiles than on controls 5 wk after seeding, but this effect had vanished by 30 wk. Comparison of the densities of new visible Acropora recruits between seeded and control ARs showed no significant difference ~13 mo after seeding. Larval seeding therefore had no long-term effect due to high post-settlement mortality (which appeared to be density-related). Results suggest that reef-rehabilitation methods that aim to harness coral sexual reproduction might better focus on rearing juveniles through early post-settlement mortality bottlenecks.
Marine ecology progress series
© 2015 Inter-Research. This paper was published in Marine Ecology Progress Series and is made available as an electronic reprint (preprint) with permission of Inter-Research. The published version is available at: [http://dx.doi.org/10.3354/meps11171]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.