Coordination of mass spawning behavior in corals
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Peter at work in the lab... |
Once per year, eight evenings after the August full moon, reef building corals in the Caribbean undergo a highly coordinated mass spawning event. Corals spawn at the same time every year, and each species has a unique time window it which it but none of the other species on the reef spawn. This timing is quite amazing, and for some species is predicable to within 5 minutes from year to year. How do corals know it is time to spawn? Our working hypothesis is that corals respond to lunar and solar light (but how?) and release both gametes and a chemical signal that tells other nearby individuals to also release. We are investigating behavioral, chemical, molecular and cellular components of this synchronized spawning event. Field work is performed in the Gulf of Mexico (Flower Garden Banks) and in the Dutch Antilles (Bonaire/Curacao). Our favorite species is the blushing star coral, S. intersepta.
A variety of field techniques are utilized including SCUBA (hot mixes, tri), rebreathers, ROVs and submarines.
The vast majority of coral reef fauna include planktonic larval stages in their life cycles. As plankton, larvae drift with the ocean currents before settling, metamorphosing, and beginning their juvenile life phases. Planktonic duration varies among species but is usually on the order of days to months, providing ample time for long-range dispersal. By examining the genetic variation in reef fish collected from Gulf of Mexico and Caribbean sites, we are investigating the relative importance of migration versus retention in maintaining fish and coral populations.
Future research will investigate processes of coral light sensing, larval retention on coral reefs, annual variation in recruitment, and coral spawning behavior.
Key references:
Vize, P.D., Embesi, J., Nickell, M. and Hagman, D.K. (2005). Tight temporal consistency of coral mass spawning at the Flower Garden Banks, Gulf of Mexico, from 1997 - 2003. Gulf Mex. Science, 23: 107-114.
Vize, P.D. (2006). Deep water broadcast spawning by Montastraea cavernosa, M. franksi and Diploria strigosa at the Flower Garden Banks, Gulf of Mexico. Coral Reefs, in press. This study used an ROV to monitor spawning in corals at depths of over 140 feet.
Reichman, J.R., Wilcox, T.P. and Vize, P.D. (2003). Characterization and organization of the PCP gene family in Symbiodinium from Hippopus hippopus: low levels of concerted evolution among PCP genes contribute to predicted isoform diversity and spectral tuning of chromophores. Mol. Biol. Evol. 20: 2143-2154.
Hagman, D.K. and Vize, P.D. (2003). Mass spawning by two brittle star species, Ophioderma rubicundum and O.squamosissimum, at the Flower Garden Banks, Gulf of Mexico. Bull. Marine Sci. 72, 871-876
Hagman, D.K., Gittings, S. and Vize, P.D. (1999). Fertilization in broadcast-spawning corals of the Flower Garden Banks National Marine Sanctuary. Gulf Mexico Sci. 16: 180-187
