The effects of air exposure on the desiccation rate and photosynthetic activity of Thalassia hemprichii and Enhalus acoroides
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The effects of air exposure on the desiccation rate and photosynthetic activity of Thalassia hemprichii and Enhalus acoroides were studied using chlorophyll fluorescence. The desiccation rate of T. hemprichii was higher than that of E. acoroides, while the critical threshold of relative water content (RWCcritical) showed opposite trend. Neither the desiccation rate nor RWCcritical of T. hemprichii was significantly affected by temperature, while the desiccation rate of E. acoroides was affected significantly. For both species, the effective photochemical efficiency of PSII decreased gradually above the RWCcritical, while declined rapidly below the RWCcritical. After initial air exposure, the relative maximum electron transport rate of both seagrasses increased gradually to a maximum and then decreased to initial value near the RWCcritical. Therefore, short-term air exposure above the RWCcritical is beneficial for both seagrasses, and the RWCcritical should be considered when examining the response of seagrass photosynthesis to air exposure and selecting transplantation sites.
KeywordsRelative Water Content Photosynthetic Capacity Electron Transport Rate Seagrass Meadow Desiccation Rate
This research was supported by the National Natural Science Foundation of China (Nos. 41306108, 41076069 and 40776086), the Natural Science Fund of Guangdong (Nos. S2013040013155), the Project of Environmental Quality Evaluation of Seagrass Bed in South China Sea (No. DOMEP (MEA)-01-03), the Public Science and Technology Research Funds Projects of Ocean (No. 201305030), and the Knowledge Innovation Program of the Chinese Academy of Sciences (No. SQ201219). We express our thanks to Mr Li Lei for their help in field sampling. We would like to thank Dr Zhang Li and Shen Pingping for their help in checking flaws in English language usage. We also would like to thank the editors and reviewers for their comments and suggestions to the manuscript.
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