A comparative study of the photosynthetic capacity in two green tide macroalgae using chlorophyll fluorescence.

Ying Wang,Tongfei Qu,Xianghai Tang,Xuexi Tang,Hui Xiao,Xinyu Zhao

doi:10.1186/s40064-016-2488-7

Abstract

Green tides have occurred in the Yellow Sea, China, every year from 2007 to 2015. The free-floating Ulva prolifera (Müller) J. Agardh was the causative macroalgal species. The co-occurring, attached U. intestinalis was also observed. Photosynthetic capacities were determined using chlorophyll fluorescence in situ and after 7 days lab acclimation, and a significant differences were noted. Pigment composition showed no obvious differences, but concentrations varied significantly, especially chlorophyll b in U. prolifera two times increase was observed after acclimation. The optimal photochemical efficiency of PS II (Fv/Fm) was significantly higher in U. prolifera. Photosynthetic rate (α), maximum relative electron transport rate (rETRmax), and minimum saturating irradiance (Ek), obtained from rapid light response curves (RLCs), showed almost the same photosynthetic physiological status as Fv/Fm. Quenching coefficients and low temperature (77 K) chlorophyll fluorescence emission spectra of thylakoid membranes analysis showed U. prolifera has a better recovery activity and plasticity of PSII than U. intestinalis. Furthermore, energy dissipation via non-photochemical quenching (NPQ) and state transitions showed efficacious photoprotection solution especially in U. prolifera suffered from the severe stresses. Results in the present study suggested that U. prolifera’s higher photosynthetic capacity would contribute to its free-floating proliferation, and efficacious photoprotection in addition to favorable oceanographic conditions and high nutrient levels support its growth and aggregation.

Highlights

Green tides formed by some green algae excessive growth has been reported in in many parts of the world, including Europe, America, Australia, and Asia (Taylor et al 2001; Nelson et al 2003, 2008; Sun et al 2008; Yabe et al 2009; Kim et al 2010; Zhang et al.2013; Wang et al 2012)
U. intestinalis always co-occurs with U. prolifera, but has not been recorded as a dominant species in the last four Yellow Sea green tides (Liu et al 2010a)
During the Yellow Sea green tides of the last five years, U. prolifera has formed floating entangled colonies, while U. intestinalis retained attached to the bottom

Summary

Introduction

Green tides formed by some green algae excessive growth has been reported in in many parts of the world, including Europe, America, Australia, and Asia (Taylor et al 2001; Nelson et al 2003, 2008; Sun et al 2008; Yabe et al 2009; Kim et al 2010; Zhang et al.2013; Wang et al 2012). Phylogenetic analysis has suggested that this species is a unique strain within the U. linza-proceraprolifera (LPP) clade (Leliaert et al 2009; Liu et al 2010a). Another green tide alga in the area is Ulva intestinalis, a cosmopolitan species like U. prolifera, with mass occurrences recorded in the eutrophic estuaries of Europe and North America (Baeck et al 2000; Cohen and Fong 2004). U. intestinalis always co-occurs with U. prolifera, but has not been recorded as a dominant species in the last four Yellow Sea green tides (Liu et al 2010a). During the Yellow Sea green tides of the last five years, U. prolifera has formed floating entangled colonies, while U. intestinalis retained attached to the bottom. Little information is available to explain this relationship and the effects of the different free-floating and attached life-forms

Methods

Results

Conclusion