Light Emitting Diode (LED) and Light Emitting Plasma (LEP) found to be highly suitable for coral aquaculture
As part of an experimental coral nursery set up by EcoDeco, biologists measured the growth of twenty scleractinian coral species under six different light treatments to optimise aquaculture. Corals (n=10) were cultured under LED (Light Emitting Diode) and LEP (Light Emitting Plasma) at irradiances of 40-60, 125-150 and 275-325 μmol m-2 s-1 over a 69-day interval. Growth was determined by measuring colony weight increase over time. A new paper in Aquaculture contains part of the project data, more specifically the growth results of Galaxea fascicularis, a model species in coral research.
G. fascicularis grew well under all conditions, with significantly higher growth under LEP at the two highest irradiance levels applied. Corals cultured under LED, with an emission skewed towards the blue part of the light spectrum, exhibited slightly lower growth rates. This finding may be the result of suboptimal water flow rates experienced by the corals, which was below 10 cm s-1 during the experiment. High intensity blue light may induce oxygen and heat accumulation in coral tissue under low water flow regimes, resulting in less efficient photosynthesis and possibly cellular damage. This, in turn, may impede coral growth. Under strong water flow (above 10-20 cm s-1), blue LED's may perform equally well as, or even outcompete, balanced light spectra including LEP. Either way, both LED and LEP lighting have shown to be very suitable for coral aquaculture. At present, both technologies have similar energy efficiencies and are still in development. Time will tell what technology will dominate the future of coral aquaculture.
Tim Wijgerde, M.Sc. is a Ph.D. candidate at Aquaculture and Fisheries, Department of Animal Sciences, Wageningen University. His research focuses on the heterotrophy of scleractinian corals. He is also the founder and editor of CoralScience.org, a website for accessible coral reef research articles and a partner with AdvancedAquarist.com.