Applicability of the microfragmentation technique to propagate corals in a fisherfolk community in the Philippines

Abstract

Coral nursery implementation is becoming a highly prevalent method of coral restoration in the Philippines. These nurseries primarily focus on fast-growing branching corals and do not commonly include massive corals. This is due to the slow growth rate and morphology of these corals, which are not conducive to traditional nursery methods. Microfragmentation is a relatively new technique that has displayed positive results for massive coral propagation. This method utilizes small coral fragments (≈1-3 cm) that are mounted on platforms, then placed in ex-situ or in-situ nurseries. The fragments exhibit rapid growth, which decreases the duration of the nursery phase before transplantation. Though microfragmentation is becoming more practiced, there is no published literature specifically focused on this method in the Philippines. The present study aimed to determine if: 1) coral specimen (i.e., putative genotype) significantly influenced growth, and 2) this method was viable in a fisherfolk community in the Western Visayas of the Philippines. Five corals of opportunity (putative genotypes) of the lobe coral, Porites lobata, were fragmented with hammer and chisel by several volunteer fisherfolk. The fragments were cultured from April-August 2018 in an in-situ fixed-leg nursery at a depth of approximately 2m. Maintenance was performed weekly and measurements of growth (i.e., volume change) were conducted monthly. The fragments were then transplanted to a selected restoration site and monitored for one month. A hierarchical Bayesian log-linear regression model indicated that 59.7% of growth (volume change) variation was attributed to coral specimen (i.e., putative genotype) and 26.4% of growth variation was attributed to the individual fragment. Overall, the average monthly increase in particular specimen’s fragment volume was 23.5% per month (95% CI, 3.43% - 43.9%/month) with the greatest monthly increase for a specimen at 30.1% per month (95% CI, 19.3 – 40.3%/month). Mean tissue spreading was determined to be 43.24cm2 /month (95% CI 44.5 – 79.4 cm2 /month) and mean linear extension was estimated to be 1.55 cm/month (95% CI, 0.92 – 2.02 cm/yr). Though high growth rates for P. lobata were documented in this study, nursery maintenance was significant due to lack of resources and location of nursery. This method may be viable and highly beneficial in established coral nurseries in the Philippines, but may not be feasible in a remote fisherfolk community