Exploring chemical cues for coral settlement and their applicability to coral restoration pipelines

Our objectives and outcomes of this project have important management implications for coral reefs. The use of tetrabromopyrrole (TBP) to settle corals eliminates the need to pre-condition substrates and has the potential to increase recruit survival and decrease labor time and cost for restoration practitioners. TBP can be used for ex-situ settlement prior to grow-out for subsequent outplanting or to prime larvae for settlement prior to deployment during direct seeding activities. In both cases, larvae can be exposed to TBP for as little as 1 hour and then rinsed to remove the majority of the TBP prior to introducing larvae to a settlement substrate. Understanding the effects, or lack thereof, of TBP treatment on coral microbiomes will allow resource managers to better assess the applicability of this method to sexual propagation pipelines for coral restoration. The use of TBP during settlement could vastly increase propagation success, efficiency and output, but as the use of TBP increases in sexual restoration in corals we want to ensure there are no adverse effects on coral recruits.
 

Identification of waterborne compounds effective at inducing coral larval settlement will fill an important knowledge gap for coral restoration efforts. These studies will help identify which organisms within the environment facilitate settlement; these organisms could then be incorporated into outplanting efforts. Once the structures of the settlement-inducing compounds are known, they could be chemically synthesized for in situ and ex situ applications. Not only will their discovery provide new tools for inducing settlement during sexual propagation, a challenging life history stage, but it will also inform managers about optimal reef conditions for coral recruitment success.