MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 301:109-118 (2005) - doi:10.3354/meps301109 Photoinhibition of photosynthesis is reduced by water flow in the reef-building coral Acropora digitifera T. Nakamura1, R. van Woesik2,*, H. Yamasaki1 1Center of Molecular Biosciences, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan2Department of Biological Sciences, Florida Institute of Technology, 150 West University Boulevard, Melbourne, Florida 32901-6988, USA *Corresponding author. Email: rvw@fit.edu ABSTRACT: While photosynthesis of symbiotic algae is essential for reef-building corals, excess irradiance inhibits photosynthesis through photoinhibition, which can lead to coral bleaching under elevated temperature conditions. Here we show that water flow reduces photoinhibition of in hospite endosymbionts in the coral Acropora digitifera. Diurnal monitoring of chlorophyll fluorescence, under 2 different flow regimes (<3 and 20 cm s1 flow rates) in an outdoor aquarium, showed reduced photoinhibition, but only under moderate flow conditions (20 cm s1). Experimental (laboratory) measurements, on time scales ranging from minutes to hours, showed that flow-mediated reductions in photoinhibition occurred not by enhancing recovery of the damaged photosystem, but rather through inducing differential photodamage. Moreover, experiments involving sequential light oscillations (500/20 and 1000/20 µmol photons m2 s1) at 3 flow regimes, <3, 10, and 20 cm s1, on a time scale ranging from hours to days, revealed water-velocity-dependent reductions of dynamic photoinhibition. These results, on time scales ranging from minutes to weeks, confirm that reduced water flow amplifies photodamage of algal photosynthesis under strong irradiance, which in turn affects coral tolerance to strong irradiance and temperature. KEY WORDS: Coral bleaching · Photoinhibition · Water-flow rates · Passive diffusion Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 301. Online publication date: October 11, 2005 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2005 Inter-Research.