@article{73b809ef7362466da945feadff7b3e7b,
title = "Measuring rates of photosynthesis of two tropical seagrasses by pulse amplitude modulated (PAM) fluorometry",
abstract = "Pulse amplitude modulated (PAM) fluorometers can potentially be used for measurements of photosynthesis rates. In this work, we attempt to assess the validity of such measurements for two common tropical seagrass species using a newly marketed portable device. This was done by comparing calculated photosynthetic electron transport rates (ETRs), based on fluorescence parameters, with rates of photosynthetic O2 evolution. While a linear relationship was found for Halophila ovalis over a wide range of photon irradiances, Halodule wrightii showed a curvilinear response with apparently lower rates of O2 evolution at high irradiance. The apparent average molar ratio of O2 evolution to ETR was 0.28 for H. stipulacea and 0.57 within the linear correlation range for H. wrightii; the deviation of the latter value from the theoretical maximal ratio of 0.25 mol O2 evolved per mol electrons transported through the photosystems is discussed. Results from in situ fluorescence measurements of these two seagrasses in a shallow intertidal habitat at high natural irradiances show that photosynthesis of H. wrightii was significantly reduced at mid-day. The results demonstrate that PAM fluorometry can be used to measure photosynthetic performances in seagrasses. However, in order to quantify ETRs it may be necessary to determine the fraction of incident light absorbed by thicker-leaved species more exactly than was done in these initial trials.",
keywords = "PAM fluorometry, Photosynthesis, Seagrasses",
author = "Sven Beer and Mats Bj{\"o}rk",
note = "Funding Information: We thank Jacqueline Uku and Andreas Weil for carrying out some of the PAM fluorometry and O 2 evolution measurements. Thanks are also due to the staff of the Institute of Marine Science, Zanzibar, for help during our stay there. M.B. further wishes to thank Sida/SAREC for financial support, and S.B. thanks Robert Weil, Stockholm, for his generous support without which this research could not have been carried out. ",
year = "2000",
month = jan,
doi = "10.1016/S0304-3770(99)00020-0",
language = "אנגלית",
volume = "66",
pages = "69--76",
journal = "Aquatic Botany",
issn = "0304-3770",
publisher = "Elsevier B.V.",
number = "1",
}