85.5 Friday, Jan. 6 Lack of Caribbean coral recruitment: A mismatch between larvae and settlement cues? DAVIES, Sarah W.*; MEYER, Eli; MATZ, Mikhail; Univ. of Texas at Austin; Univ. of Texas at Austin; Univ. of Texas at Austin email@example.com
Larval recruitment is critical for establishment and recovery of coral populations. Caribbean coral recruitment success has been low in recent years, especially in the northernmost reef in the Gulf of Mexico, the Flower Garden Banks (FGB). In contrast, recruitment success remains high among Pacific corals. We investigated whether these regional differences might be explained by the lack of appropriate Caribbean settlement cue, or by impaired cue perception by Caribbean coral larvae. We collected natural settlement cue (crustose coralline algae, CCA) from Caribbean (Florida, FGB, Bonaire) and Pacific (Great Barrier Reef (GBR), Pohnpei, Guam) locations, and tested these cues on four species of GBR corals (Acropora millepora, A. tenuis, Favia lizardensis, and Ctenactis echinata) and three FGB species (Montastrea franksi, Diploria strigosa, and Stephanocoenia intersepta). Larvae from both regions responded strongly to specific cues, suggesting that low Caribbean recruitment is not due to impaired cue perception. Caribbean CCA induced settlement in both Caribbean and Pacific species, indicating that appropriate cue is present on Caribbean reefs. Settlement cue rankings differed among species, suggesting species-specific preferences. Among Caribbean corals, we found that larvae responded more strongly to Caribbean CCA than Pacific, suggesting co-adaptation of corals and CCA. Through high-throughput 454 sequencing of small subunit (SSU) ribosomal amplicons, each CCA sample was characterized revealing high diversity among samples and a positive correlation between relative proportion of CCA sequences (of any species) and settlement response. Overall, our results indicate that lack of coral recruitment in the Caribbean does not result from absence of settlement cue or impaired responsiveness to that cue, and must therefore result from some other factor.