Title: PHOTOACCLIMATION AND INDUCTION OF LIGHT-ENHANCED CALCIFICATION IN THE MESOPHOTIC CORAL EUPHYLLIA PARADIVISA

Abstract: Depth gradient is characterized by inherent changes in light which lead to several adaptation strategies within corals and their symbionts. In this study, the strictly mesophotic coral Euphyllia paradivisa from the Red Sea served as a model to determine the strategies of acclimation to different light conditions and to study photosynthesis and calcification coupling. The coral's physiology was examined after one year of acclimation under three sets of light conditions: shallow (3m); deep (50m, native population); and total darkness. Although photosynthesis was almost similar at both light treatments under a P vs. E curve, light enhanced-calcification was evident only in shallow acclimated corals leading also to six fold larger linear extension rates. The dark treated specimens were completely bleached and photoacclimation to shallow was expressed in enhanced respiration, higher zooxanthellate densities per polyp and lower chlorophyll per cell. We discuss the adaptation mechanisms of mesophotic corals to shallow water and to the aphotic zone. We conclude that E. paradivisa can adapt to various light conditions by controlling metabolic rates and growth energy investment and therefore can survive temporal and spatial effects of low light stress. It is generally accepted that ecological advantages acquired by corals in their native habitat may jeopardize their survival in a case of abrupt environmental changes. However to the strictly mesophotic E. paradivisa in the Red Sea shallow waters may be advantageous.

Authors: Eyal G, Cohen I, Eyal-Shaham L, Ben-Zvi O, Loya Y

Presentation: Oral

Session: 29

Date: 06/21/16

Time: 17:00

Location: 308 A/B

Back