Photoacclimation, growth and distribution of massive coral species in clear and turbid waters

Abstract

Massive coral species play a key role in coral reef ecosystems, adding significantly to physical integrity, long term stability and reef biodiversity. This study coupled the assessment of the distribution and abundance of 4 dominant massive coral species, Diploastrea heliopora, Favia speciosa, F. matthaii and Porites lutea, with investigations into species-specific photoacclimatory responses within the Wakatobi Marine National Park of southeast Sulawesi, Indonesia, to determine the potential of photoacclimation to be a driver of biological success. For this, rapid light curves using pulse amplitude modulated (PAM) chlorophyll a fluorescence techniques were employed with additional manipulations to circumvent differences of light quality and absorption between species and across environmental gradients. P. lutea was examined over a range of depths and sites to determine patterns of photoacclimation, and all 4 species were assessed at a single depth between sites for which long-term data for coral community structure and growth existed. Light availability was more highly constrained with depth than between sites; consequently, photoacclimation patterns for P. lutea appeared greater with depth than across environmental gradients. All 4 species were found to differentially modify the extent of non-photochemical quenching to maintain a constant photochemical operating efficiency (qP). Therefore, our results suggest that these massive corals photoacclimate to ensure a constant light-dependent rate of reduction of the plastoquinone pool across growth environments.KEY WORDS: Chlorophyll a fluorescence ⋅ Zooxanthellae ⋅ PAM ⋅ Photoacclimation ⋅ Massive coral ⋅ Indo-Pacific Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 369: [77][78][79][80][81][82][83][84][85][86][87][88] 2008 adjustments that arise following a change in light environment (Falkowski & LaRoche 1991) and is genetically constrained (MacIntyre et al. 2002). Zooxanthellae (in hospite and isolated) photoacclimate in the same way as for many other microalgae, by adjusting various cellular constituents including pigmentation and number of 'reaction centres' for light harvesting (Falkowski & Dubinsky 1981, Iglesias-Prieto & Trench 1994. However, these patterns of photoacclimation have been largely deduced using cultures of zooxanthellae isolated from their coral host. Quantifying zooxanthellae photoacclimation in hospite is more problematic. In particular, the methods employed are often destructive to the coral and thus not practical to describe broad ecosystem processes (Falkowski & Dubinsky 1981). These techniques also require removal of the corals from their habitat and may thus perturb their natural physiological state (Jones & Hoegh-Guldberg 2001). Instead, researchers have turned towards the use of nondestructive chlorophyll a (chl a) fluorescence induction techniques, which are popular for examining phytoplankton and higher plant photophysiology, to investigate coral photophysiology; in particu...

Utility of Photochemical Traits as Diagnostics of Thermal Tolerance amongst Great Barrier Reef Corals

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The Future of Coral Reefs Subject to Rapid Climate Change: Lessons from Natural Extreme Environments

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Screening by coral green fluorescent protein (GFP)-like chromoproteins supports a role in photoprotection of zooxanthellae

“…Even at the scale of a single shallow-water colony, there are large variations in light exposure of the coral's tissues controlled by factors such as seasonal and diel changes in surface irradiance, changes in the absorbing and scattering materials in the water column, orientation of the tissue surface relative to the incident irradiance and wave-focusing effects (Falkowski et al 1990;Veal et al 2010;Kaniewska et al 2011). The shallow-water environments where reefbuilding corals thrive are typified by irradiances often greater than photon fluxes of *300-750 lmol m -2 s -1 that saturate photosynthesis of the algal symbionts in hospite (Gorbunov et al 2001;Levy et al 2004;Hennige et al 2008). As such, some shallow-water corals live in Communicated by Biology Editor Dr. Anastazia Banaszak…”