Collaborative Research: Spawning and Fertilization in the Caribbean Coral Montastraea Annularis Sensu Lato

Florida State University, Tallahassee FL

Investigators

Abstract

Members of the Montastraea annularis complex are the major reef building corals in the Caribbean, and they have been a model system for studies of the ecology and geology of coral reefs. Three taxa have been described (M annularis, M ftanksi and M faveolata), although their status as separate species has been questioned. Since the 1980's, these corals, along with several others, have declined drastically in abundance at many sites. In order for M annularis to persist and recover, it must reproduce. However, almost nothing is known about the reproductive success of this or any Caribbean coral. The major focus of this proposal is to provide a comprehensive understanding of the spawning behavior, gamete compatibilities and fertilization rates of the three members of the M annularis complex. Data collected previously from Panama suggest that differences in spawning times and gametic compatibility are sufficient to maintain reproductive boundaries among the three taxa. These barriers have the additional consequence of increasing the distance between potential mates on many reefs. Fertilization rates in the field appear to be quite low, most likely because of the distances between spawning conspecifics. Selfed crosses are generally unsuccessful. Preliminary work has established research protocols for collecting these types of data, but the bulk of the data collection over a range of spawning conditions lies ahead. We propose to accomplish this through a five-year program in Panama. Laboratory experiments will determine how gamete longevity and gamete concentration influence fertilization success. This provides important information for determining the consequences of asynchronous spawning. Field studies will document the spawning times of each taxon and the fertilization rates and gamete concentrations in the water column during spawning events. Drogues that simulate gamete dispersal will be used to determine the patterns of dispersal under a variety of conditions in order to get a more robust understanding of how gametes can be advected from the reef. This work will provide the first information on in situ rates of fertilization success and the mechanisms that influence fertilization rates for any Caribbean hard coral. The importance of this species to coral reef communities and the recent declines in this coral make the proposed study all the more timely.