Easing bottlenecks in the early life history of coral

As a practical matter, the implementation of many proposed ‘novel interventions’ would involve active breeding/propagation of improved corals and establishing them in reef populations at large scales. Corals must navigate... [ view full abstract ]

As a practical matter, the implementation of many proposed ‘novel interventions’ would involve active breeding/propagation of improved corals and establishing them in reef populations at large scales. Corals must navigate many complex life history steps to successfully recruit on a reef and any of these stages may represent a bottleneck in certain circumstances. With years of experience and development, procedures have been developed to successfully assist many of these stages including prediction of spawning time, capturing and fertilizing gametes, larval culture, and settlement in most regions and with many species.  The big remaining challenge is survivorship of settlers after placement on the reef.  Both K- and r- type strategies may be hypothesized to address this restoration challenge, either investing in costly post-settlement care for grow-out to a more survivable size, or attempting to overcome high mortality with massive, low-investment propagule inputs.  However, it seems that neither of these strategies lends itself to the tremendous upscaling of coral restoration goals now being contemplated.  Another approach is to design specialized settlement substrates (‘seeding units’) that can provide acceptable settlement habitat along with features (e.g. materials, coatings, or shapes) that enhance survivorship for small settlers on the reef.  This challenge is at the forefront of current restoration research, leveraging both ecological and engineering expertise.