The different responses of growth and photosynthesis to NH4+ enrichments between Gracilariopsis lemaneiforrnis and its epiphytic alga Ulva lactuca grown at elevated atmospheric CO2

• Published in: Marine Pollution Bulletin
• Main Authors: Ji, Zhiwei, Zou, Dinghui, Gong, Jingyu, Liu, Chunxiang, Ye, Changpeng, Chen, Yuning
• Format: Report
• Language: English
• Published: PERGAMON-ELSEVIER SCIENCE LTD 2019
• Subjects: Eutrophication; Ammonium enrichments; Elevated CO2; Macroalgae; Gracilariopsis lernaneifonnis; Ulva lactuca; Environmental Sciences & Ecology; Marine & Freshwater Biology; Environmental Sciences; OCEAN ACIDIFICATION; AMMONIUM TOXICITY; INORGANIC CARBON; NITROGEN; GIGARTINALES; MECHANISMS; RHODOPHYTA; Ocean acidification
• Online Access: http://ir.ihb.ac.cn/handle/342005/31267; https://doi.org/10.1016/j.marpolbul.2019.04.049

We investigated how elevated CO2 affects the responses of Gracilariopsis lemaneiformis and Ulva lactuca to NH4+ enrichments. All algae were incubated under four nutritional conditions (zero addition, 100, 500, and 2500 mu M NH4+), and two CO2 levels (390 ppm and 1000 ppm). The growth, photosynthesis, and soluble protein contents of both species increased under the eutrophication condition (100 mu M NH4+). However, the growth and carotenoid contents of the two species declined when NH4+ concentration increased. Under the super eutrophication condition (2500 mu M NH4+), all indexes measured in G. lemaneiformis were suppressed, while the growth and photosynthesis in U. lactuca changed indistinctively, both compared with the control. Moreover, under the super eutrophication condition, elevated CO2 reduced the suppression in the growth of G. lemaneiformis, but decreased the growth of U. lactuca. Nonetheless, G. lemaneifonnis displayed much lower growth rates than U. lactuca under the super eutrophication and elevated CO2 condition.