Rapid environmental changes are threatening corals's survival, both now and in the future, as conditions exceed their tolerance. Many of these stressful conditions are human-caused, including warming temperatures and strengthening storms due to climate change. Replanting and restoring corals will not ultimately succeed if they are not able to withstand present and near-future conditions occurring on reefs. Thus, humans must arrest climate change and other forms of environmental degradation, and as we restore coral populations, we want to include corals that have the best chance of surviving stressful conditions.
Organisms can adapt to environmental changes via evolutionary processes, and sometimes surprisingly rapidly. However, this requires that organisms are successfully reproducing, creating new individuals with new characteristics, some of which may include increased tolerance of stressors.
Unfortunately, such reproduction fails as the population declines. SECORE’s approach to coral restoration aims to assist successful reproduction that creates these new generations of corals and provides the (otherwise lacking) raw material for natural adaptive processes. This approach embodies the current best restoration practice recommendation from the Coral Restoration Consortium Genetics Working Group (Baums et al. 2019; see below).
Meanwhile, by partnering with academic colleagues, SECORE participates in research on different approaches that aim at more actively improving the capacity of restored corals to withstand warmer, more stressful conditions.
- Symbiosis: A current collaboration with the University of Miami and Shedd Aquarium investigates techniques to steer baby corals to initiate their symbiosis with an algal partner that is especially tolerant of warm temperatures. We then follow the babies when outplanted to reefs with different temperature regimes to test if this early association with thermally tolerant symbionts might improve their resilience in later life. In September 2019, settlers of the massive coral Orbicella faveolata were inoculated with either the thermally tolerant or the more standard type of symbionts and outplanted to two reefs in Eleuthera, Bahamas to follow their growth and survival.
- Selective Breeding: The CORALASSIST project led by Dr. James Guest (Newcastle University) is testing the thermal tolerance of adult colonies in Palau and conducting controlled breeding to determine if this thermal tolerance is passed to their offspring, as well as investigating potential physiological trade-offs of this thermal tolerance trait. SECORE is collaborating to attempt propagating these crosses for restoration and outplanting.
- Gene Banking: SECORE is collaborating in planning effective strategies for assembling and fruitfully utilizing genetic banks for corals. Specifically, coral sperm banks (i.e. under cryopreservation) are seen as a key genetic tool to implement novel genetic interventions that might be developed and deemed beneficial in the future. SECOREs field teams in Curacao and Mexico are collaborating in local efforts to cryo-archive sperm samples from local coral populations.
- "Are younger corals better parents?": This life history research project is a collaboration with Dr. Iliana Baums (does reproductive success decline with age?) and could change restoration practices considerably. Corals are generally assumed to be immortal, especially species that fragment easily, like staghorn coral, as the same genetic individual may persist through many 'generations' of fragments that establish, grow, and fragment again. However, Baum's genetic studies suggest that corals accumulate mutations in their genomes over these long life spans which we suspect may eventually impair their reproductive success. SECORE's new generation of elkhorn corals at the Sea Aquarium reef (born in 2011) form a cohort of new genotypes of known age which is a key asset to test this hypothesis that younger corals indeed produce more or better quality offspring than their older neighbors. Old Age: Because natural coral recruitment has been failing over a long period of time in some Caribbean reefs, many potential parent corals that we are using in restoration efforts are extremely old. We hypothesize that over a very long life span involving millions or perhaps billions of cell divisions, small genetic mistakes may accumulate in these parents and yield offspring with lower fitness. We are testing this hypothesis in elkhorn corasl, by comparing the quality of gametes and offspring of older parent colonies with the offspring of young, 8 yr old parents resulting from SECOREs early efforts (Laboratory-bred corals reproduce in the wild).
Most importantly, almost all of these approaches require active coral breeding and thus, the techniques for effective upscaling of crossing, larval production, and outplanting that are SECOREs current developmental focus will be key to applying these intervention techniques as they are deemed ready for 'prime time'.
- Laboratory-bred corals reproduce in the wild, Sciencedaily
- Global warming impairs stock-recruitment dynamics of corals. Hughes, T.P., Kerry, J.T., Baird, A.H., Connolly, S.R., Chase, T.J., Dietzel, A., Hill, T., Hoey, A.S., Hoogenboom, M.O., Jacobson, M. and Kerswell, A., 2019. Nature 568:387.
- Best restoration practice recommendation from the Coral Restoration Consortium Genetics Working Group
- Considerations for maximizing the adaptive potential of restored coral populations in the western Atlantic. Baums IB, Baker AC, Davies SW, Grottoli AG, Kenkel CD, Kitchen SA, Kuffner IB, LaJeunesse TC, Matz MV, Miller MW, Parkinson JE, Shantz AA., 2019. Ecol Appl. 29: e01978.
- James Guest's CORALASSISTlab