AB 7:153-157 (2009)  -  doi:10.3354/ab00148

Photosynthetic responses of Halophila stipulacea to a light gradient. II. Acclimations following transplantation

Yoni Sharon1,2,*, João Silva3, Rui Santos3, John W. Runcie4, Mark Chernihovsky2, Sven Beer1

1Department of Plant Sciences, Tel Aviv University, Tel Aviv 60078, Israel
2The Interuniversity Institute for Marine Sciences, POB 469, Eilat 88103, Israel
3ALGAE - Marine Plant Ecology Research Group, Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
4School of Biological Sciences, University of Sydney, New South Wales 2006, Australia

ABSTRACT: Halophila stipulacea is the dominant seagrass in the Gulf of Aqaba (northern Red Sea), where it grows from the intertidal to depths exceeding 50 m. Its successful growth under such a broad irradiance gradient shows either a high plasticity or is caused by longer-term adaptations to the various depths, possibly resulting in the formation of ecotypes. In April 2008 we transplanted shoots of this seagrass between the extreme depths of its distribution at the study site (8 and 33 m) in order to evaluate its acclimation potential to various irradiances. We compared photosynthetic parameters derived from light response curves generated by PAM fluorometry (so-called rapid light curves, RLC) and measured chlorophyll a and b concentrations. RLCs from the shallow (~400 µmol photons m–2 s–1 at midday) and deep (~35 µmol photons m–2 s–1 at midday) sites were characteristic for high- and low-light growing plants, respectively, and the transplanted seagrasses acclimated to their new environments within 6 d, at which time their RLCs resembled those of the original plants growing at the depths to which they had been transplanted. Concentrations of both chlorophyll a and b decreased or increased when the plants were transferred to high- vs. low-light environments, respectively, but the chlorophyll a:b ratios remained constant. These fast changes in photosynthetic responses and light absorption characteristics in response to changing light environments points to Halophila stipulacea as being a highly plastic seagrass with regard to irradiance, which may partly explain its abundance across a wide range of irradiances along the depth gradient that it occupies.

KEY WORDS: Acclimation · Depth gradient · Halophila stipulacea · Irradiance · Photosynthesis · Pigments · Seagrass

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Cite this article as: Sharon Y, Silva J, Santos R, Runcie JW, Chernihovsky M, Beer S (2009) Photosynthetic responses of Halophila stipulacea to a light gradient. II. Acclimations following transplantation. Aquat Biol 7:153-157

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