RT Journal Article
SR Electronic
T1 Light-harvesting in mesophotic corals is powered by a spatially efficient photosymbiotic system between coral host and microalgae
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.12.04.411496
DO 10.1101/2020.12.04.411496
A1 Netanel Kramer
A1 Raz Tamir
A1 Or Ben-Zvi
A1 Steven L. Jacques
A1 Yossi Loya
A1 Daniel Wangpraseurt
YR 2020
UL http://biorxiv.org/content/early/2020/12/06/2020.12.04.411496.abstract
AB The coral-algal photosymbiosis fuels global coral-reef primary productivity, extending from sea level to as deep as 150 m (i.e., mesophotic). Currently, it is largely unknown how such mesophotic reefs thrive despite extremely limited light conditions. Here, we show that corals exhibit a plastic response to mesophotic conditions that involves a spatially optimized regulation of the bio-optical properties by coral host and symbiont. In contrast to shallow corals, mesophotic corals absorbed up to three-fold more light, resulting in excellent photosynthetic response under light conditions of only ~3% of the incident surface irradiance. The enhanced light harvesting capacity of mesophotic corals is regulated by average refractive index fluctuations in the coral skeleton that give rise to optical scattering and facilitate light transport and absorption by densely pigmented host tissue. The results of this study provide fundamental insight into the energy efficiency and light-harvesting mechanisms underlying the productivity of mesophotic coral reef ecosystems, yet also raise concerns regarding their ability to withstand prolonged environmental disturbances.Competing Interest StatementThe authors have declared no competing interest.