For the past 500,000 years, Acropora cervicornis (staghorn coral) was one of the dominant reef building corals in the Caribbean. But over last few decades, A. cervicornis populations have suffered a dramatic decline (>95% mortality) throughout the entire Caribbean (Griffin et al 2012). As a result of this decline, adult populations typically have low densities and genetic diversity, resulting in a reduction in genetic connectivity for this genus. As these populations continue to decline, proactive intervention is becoming increasingly warranted
In the last decades coral gardening has become an increasing important tool in reef restoration (Lirman 2008). Coral gardening consists of growing corals in situ at a nursery site and then transplanting these coral frags back onto natural reef enviros once they have grown to an appropriate size. The corals outplanted for this study were grown in the Coral Restoration Foundation’s (CRF) coral nursery offshore of Tavernier, FL. All outplanting, measuring and data collection was completed at Molasses Reef, a spur and groove reef offshore of Key Largo, FL. Although very little A. cervicornis is found naturally at Molasses Reef today, skeletal remains and photo documentation suggests that the species was abundant until the mid 1980s.
A cervicornis is composed of low diversity, predominantly clonal populations of corals maintained by asexual fragmentation with clones shown to span distances as great as 30-50 m (Bowden-Kerby 2008). The clonal nature of the species has major implications for the restoration of this threatened coral. Because A. cervicornis fragments easily to create clonal populations, restoration is fairly simple but the highly clonal nature of the species might also present unforeseen challenges, over wide environmental gradients, as each genotype may be highly adapted to a narrow range of environmental tolerances.
Statistics still need to be run, but the data MRDF and CRF biologists collected in 2012 for the staghorn coral fragments outplanted are showing a distinct difference in growth rate amongst the three genotypes. 20 fragments of each genotype were planted. The three different genotypes used in this study are denoted by K1, K2 and K3. We had .02% mortality rate with only one coral fragment not surviving year 1 (K1). All genotypes had the lowest average growth rate from August to September (tropical storm Isaac) and K1’s and K3’s both had the highest average growth rate from May to June.
|Average % growth in one year|
Data analysis of genotype growth at various depths and locations is underway to further investigate difference in environmental tolerances.