Bottlenecks to coral recovery in the Seychelles

Chong-Seng, K.M., Graham, N.A.J., and Pratchett, M.S. (2014) Bottlenecks to coral recovery in the Seychelles. Coral Reefs, 33 (2). pp. 449-461.

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Abstract

Processes that affect recovery of coral assemblages require investigation because coral reefs are experiencing a diverse array of more frequent disturbances. Potential bottlenecks to coral recovery include limited larval supply, low rates of settlement, and high mortality of new recruits or juvenile corals. We investigated spatial variation in local abundance of scleractinian corals in the Seychelles at three distinct life history stages (recruits, juveniles, and adults) on reefs with differing benthic conditions. Following widespread coral loss due to the 1998 bleaching event, some reefs are recovering (i.e., relatively high scleractinian coral cover: 'coral-dominated'), some reefs have low cover of living macrobenthos and unconsolidated rubble substrates ('rubble-dominated'), and some reefs have high cover of macroalgae ('macroalgal-dominated'). Rates of coral recruitment to artificial settlement tiles were similar across all reef conditions, suggesting that larval supply does not explain differential coral recovery across the three reef types. However, acroporid recruits were absent on macroalgal-dominated reefs (0.0 ± 0.0 recruits tile−1) in comparison to coral-dominated reefs (5.2 ± 1.6 recruits tile−1). Juvenile coral colony density was significantly lower on macroalgal-dominated reefs (2.4 ± 1.1 colonies m−2), compared to coral-dominated reefs (16.8 ± 2.4 m−2) and rubble-dominated reefs (33.1 ± 7.3 m−2), suggesting that macroalgal-dominated reefs have either a bottleneck to successful settlement on the natural substrates or a high post-settlement mortality bottleneck. Rubble-dominated reefs had very low cover of adult corals (10.0 ± 1.7 %) compared to coral-dominated reefs (33.4 ± 3.6 %) despite no statistical difference in their juvenile coral densities. A bottleneck caused by low juvenile colony survivorship on unconsolidated rubble-dominated reefs is possible, or alternatively, recruitment to rubble-dominated reefs has only recently begun. This study identified bottlenecks to recovery of coral assemblages that varied depending on post-disturbance habitat condition.

Item ID: 33423
Item Type: Article (Refereed Research - C1)
Keywords: Scleractinian corals, phase shifts, larval supply, recruitment, degradation, rubble, macroalgae
ISSN: 1432-0975
Funders: Australian Research Council (ARC), Western Indian Ocean Marine Science Association, Seychelles Fishing Authority (SFA)
Projects and Grants: Western Indian Ocean Marine Science Association Marine Research Grant
Date Deposited: 28 May 2014 01:51
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 50%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 50%
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