Photosynthetic fluorescence characteristics of six macroalgae species in seaweed beds of Gouqi Island, Zhejiang, China.

Abstract

The study of photosynthetic fluorescence characteristics of algae is important for the analy-sis of photosynthesis and carbon sequestration of algae. In July 2017, six common species of macroalgae found in Gouqi seaweed beds were collected, including Ulva pertusa, Cladophora stimpsonii, Grateloupia livida, Sargassum thunbergii, Polysiphonia urceolata, and Hizikia fusifarme. In the field, the maximal quantum yieids of photosystem2(Fv/Fm) and rapid curves (RLCs) were mea-sured by using pulse-amplitude modulated fluorometer (Diving-PAM). The results showed that the measured maximal quantum yields of U. pertusa, C. stimpsonii, G. livida, S. thunbergii, P. urceolata, and H. fusiforme were 0.702, 0.704, 0.457, 0.618, 0.421 and 0.567, respectively. The Fv'/Fm' of six species were in order of C. stimpsonii>U. pertusa>S. thunbergii＞H. fusiforme＞G. livida＞P. urceolata. The difference between each species and significant difference was found in U. pertusa, C. stimpsonii, and H. fusiforme. H. fusiforme, S. thunbergii and U. pertusa had higher Pm and α than other species, indicating their higher photosynthetic capacity and better adaptation in higher light condition. However, G. livida had higher α but lower Ik, indicating G. livida had higher photosynthetic capacity in low light condition. In a word, differences of photosynthetic capacity and light intense tolerance between the three phyla of macroalgae were found and we suggested H. fusiforme, S. thunbergii and U. pertusa had stronger photosynthetic capacity and light intense tolerance. Our results could provide theoretical basis for the seaweed bed conservation and carbon sequestration of macroalgae.