Chemical cues for habitat selection by Caribbean coral larvae

As natural habitats are increasingly lost or degraded, there is a need to determine the mechanisms that organisms use to locate suitable habitats and to identify if adaptation is possible to new or altered locations. The importance of chemical cues during the settlement process is becoming well recognized for many invertebrate larvae, including coral larvae; however, the chemical nature of these cues is poorly understood. Coral settlement studies have mostly focused on surface-bound chemical cues and the role these play once contacted by settling larvae. Although coral larvae do not possess the same chemical detection systems or similar swimming ability as fish larvae, chemical cues can both positively and negatively influence their substrate preferences. We will describe methods developed and used to understand the types of compounds released by coral reef organisms as extracellular metabolites, with an emphasis on those compounds involved in settlement site selection by coral larvae. Understanding these chemical cues could facilitate settlement and recruitment of coral larvae for restoration purposes.