ABSTRACT: Symbiotic reef corals exude large volumes of mucus when exposed to environmental conditions that challenge the integrity of the coral-algae endosymbiosis. Here, the physiological consequences of CO2-limitation within the ‘dark’ photosynthetic reactions of the algal endosymbionts (‘zooxanthellae’) are investigated as the possible cause of the release of 2 different forms of mucus: mucus-polysaccharide and mucus-lipid. This mechanism may explain why the experimental addition of specific host-derived free amino acids (commonly referred to as ‘host factors’) enhances photosynthate release and carbon fixation rates from in vitro zooxanthellae. Furthermore, it reinforces the often-ignored importance of the coral host in maintaining the stability and functioning of the intact symbiosis in the face of environmental stress, even supporting the possibility that disruption to host-controlled processes ultimately triggers the breakdown of the symbiosis leading to the mass expulsion of zooxanthellae (‘coral bleaching’).
KEY WORDS: Coral bleaching · Host release factor · Photoinhibition · Lipogenesis
Full text in pdf format | Cite this article as: Wooldridge SA
(2009) A new conceptual model for the enhanced release of mucus in symbiotic reef corals during ‘bleaching’ conditions. Mar Ecol Prog Ser 396:145-152. https://doi.org/10.3354/meps08310
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