Over the last 70 weeks we have been monitoring the growth (linear extension) of the coral transplants upon our frames and found some interesting results!
For these measurements we have coral frames under 3 different transplantation methods:
Single species Acropora formosa
Single species Acropora parahemprichii
Mixed species A formosa & A parahemprichii
For each of these methods we have three replicate frames, and each frame started with 30 coral fragments all between 8-10cm size.
Average growth in single-species frames seems to be higher than when the same species is planted on a mixed frame. This result held true for both of the species of Acropora.
Why might this be?
Generally it’s been thought that corals grow better when they are planted in close proximity to one another (Density-dependent effects on initial growth of a branching coral under restoration, Griffin et al. 2015) or in multi-species clusters (Performance of single versus mixed coral species for transplantation to restore degraded reefs, Cabaitan et al 2015).
Possibly the reason that our transplants seem to be doing the opposite and growing slower when mixed could be that these two Acropora species may hold similar roles in the ecosystem and are competing with oneanother for space and resources… therefore inhibiting each other’s growth when together.