Effects of water turbidity on the symbiotic zooxanthella of hermatypic corals

Abstract

Five species of reef-building coral (Acropora millepora, Acropora nasuta, Pocillopora damicornis, Galaxea fascicularis and Porites lutea) were used to study the effects of water turbidity stress on the symbiotic zooxanthella. The gradients of water turbidity were simulated using a solution containing different concentrations of inactivated Escherichia coli. The results revealed that the photosynthetic efficiency and density of the symbiotic zooxanthella were both restricted by the water turbidity, and that high turbidity corresponds to high inhibitory action. The results also showed that the tolerance of the five symbiotic zooxanthella to water turbidity differed, with the massive corals Galaxea fascicularis and Porites lutea having strong tolerance, and that of the branching corals Acropora millepora, Acropora nasuta and Pocillopora damicornis being relatively weak.