Effect of copper on algal-host interactions in the symbiotic coral Plesiastrea versipora

Abstract

Blue and green morphs of the scleractinian coral Plesiastrea versipora were exposed to increasing amounts of copper for periods of 12 (0-5.04 μM) to 36 d (two cycles of 0-7.55 μM). Algae were not expelled and there was no decrease in photosynthesis or chlorophyll a. Chlorophyll c decreased in only one out of four experiments. Total carotenoids increased in all the experiments. Two host signalling compounds that regulate algal carbon metabolism, host release factor (HRF) which stimulates algal photosynthate release, and photosynthesis inhibiting factor (PIF) which partially inhibits photosynthetic carbon fixation, were examined. PIF activity was slightly higher after 16 and 36 d of exposure t..