Evaluating bloom potential of the green-tide forming alga Ulva ohnoi under ocean acidification and warming

Photoperiods have an important impact on macroalgae living in the intertidal zone. Ocean acidification also influences the physiology of macroalgae. However, little is known about the interaction between ocean acidification and photoperiod on macroalgae. In this study, a green alga Ulva linza was cultured under three different photoperiods (L: D = 8:16, 12:12, 16:8) and two different CO2 levels (LC, 400 ppm; HC, 1,000 ppm) to investigate their responses. The results showed that relative growth rate of U. linza increased with extended light periods under LC but decreased at HC when exposed to the longest light period of 16 h compared to 12 h. Higher CO2 levels enhanced the relative growth rate at a L: D of 8:16, had no effect at 12:12 but reduced RGR at 16:8. At LC, the L: D of 16:8 significantly stimulated maximum quantum yield (Yield). Higher CO2 levels enhanced Yield at L: D of 12:12 and 8:16, had negative effect at 16:8. Non-photochemical quenching (NPQ) increased with increasing light period. High CO2 levels did not affect respiration rate during shorter light periods but enhanced it at a light period of 16 h. Longer light periods had negative effects on Chl a and Chl b content, and high CO2 level also inhibited the synthesis of these pigments. Our data demonstrate the interactive effects of CO2 and photoperiod on the physiological characteristics of the green tide macroalga Ulva linza and indicate that future ocean acidification may hinder the stimulatory effect of long light periods on growth of Ulva species.

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Research on the Seasonal Succession of Green Tide and Tolerance of a Causative Seaweed Ulva ohnoi to Low Salinity and Desiccation at the North Pond of Osaka Nanko Bird Sanctuary

Journal of Japan Society of Civil Engineers Ser B2 (Coastal Engineering) ◽

10.2208/kaigan.67.i_1136 ◽

2011 ◽

Vol 67 (2) ◽

pp. I_1136-I_1140 ◽

Cited By ~ 1

Author(s):

Midori YOSHIMURA ◽

Susumu YAMOCHI

Keyword(s):

Seasonal Succession ◽

Green Tide ◽

Low Salinity ◽

The North ◽

Ulva Ohnoi

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Mitochondrial and chloroplast genome sequences of Ulva ohnoi, a green-tide-forming macroalga in the Southern coastal regions of Japan

Mitochondrial DNA Part B ◽

10.1080/23802359.2018.1483778 ◽

2018 ◽

Vol 3 (2) ◽

pp. 765-767 ◽

Cited By ~ 3

Author(s):

Shigekatsu Suzuki ◽

Haruyo Yamaguchi ◽

Masanori Hiraoka ◽

Masanobu Kawachi

Keyword(s):

Chloroplast Genome ◽

Green Tide ◽

Genome Sequences ◽

Coastal Regions ◽

Ulva Ohnoi

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Ocean acidification and nutrient limitation synergistically reduce growth and photosynthetic performances of a green tide alga <i>Ulva linza</i>

10.5194/bg-2018-1 ◽

2018 ◽

Cited By ~ 1

Author(s):

Guang Gao ◽

John Beardall ◽

Menglin Bao ◽

Can Wang ◽

Wangwang Ren ◽

...

Keyword(s):

Growth Rate ◽

Ocean Acidification ◽

Nutrient Limitation ◽

Nitrate Reductase Activity ◽

Reductase Activity ◽

Green Tide ◽

Soluble Protein Content ◽

Green Tides ◽

P Limitation ◽

Adult Plants

Abstract. Large-scale green tides have been invading the coastal zones of the western Yellow Sea annually since 2008. Meanwhile, oceans are becoming more acid due to continuous absorption of anthropogenic carbon dioxide and intensive seaweed cultivation in Chinese coastal areas is leading to severe regional nutrient limitation. However, little is known the combined effects of global and local stressors on the eco-physiology of bloom-forming algae. We cultured Ulva linza under two levels of pCO2 (400 and 1000 μatm) and four treatments of nutrient (nutrient repletion, N limitation, P limitation, and N & P limitation) to investigate the physiological responses of this green tide alga to the combination of ocean acidification and nutrient limitation. For both sporelings and adult plants, elevated pCO2 did not affect the growth rate when cultured under nutrient replete conditions but reduced it under P limitation; N or P limitation by themselves reduced growth rate. P limitation resulted in a larger inhibition in growth for sporelings compared to adult plants. Sporelings under P limitation did not reach the mature stage after 16 days of culture while those under P repletion became mature by day 11. Elevated pCO2 reduced net photosynthetic rate for all nutrient treatments but increased nitrate reductase activity and soluble protein content under P replete conditions. N or P limitation reduced nitrate reductase activity and soluble protein content. These findings indicate that ocean acidification and nutrient limitation would synergistically reduce the growth of Ulva species and may thus hinder the occurrence of green tides in a future ocean environment.

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Expected CO2-induced ocean acidification modulates copper toxicity in the green tide alga Ulva prolifera

Environmental and Experimental Botany ◽

10.1016/j.envexpbot.2016.12.007 ◽

2017 ◽

Vol 135 ◽

pp. 63-72 ◽

Cited By ~ 25

Author(s):

Guang Gao ◽

Yameng Liu ◽

Xinshu Li ◽

Zhihua Feng ◽

Zhiguang Xu ◽

...

Keyword(s):

Ocean Acidification ◽

Copper Toxicity ◽

Ulva Prolifera ◽

Green Tide

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Differential Photosynthetic Response of a Green Tide Alga Ulva linza to Ultraviolet Radiation, Under Short- and Long-term Ocean Acidification Regimes

Photochemistry and Photobiology ◽

10.1111/php.13083 ◽

2019 ◽

Vol 95 (4) ◽

pp. 990-998 ◽

Cited By ~ 2

Author(s):

Jing Ma ◽

Wen Wang ◽

Liming Qu ◽

Xiaoyan Liu ◽

Zhiqin Wang ◽

...

Keyword(s):

Ultraviolet Radiation ◽

Ocean Acidification ◽

Green Tide ◽

Photosynthetic Response ◽

Ulva Linza ◽

Short And Long Term

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Ocean acidification and nutrient limitation synergistically reduce growth and photosynthetic performances of a green tide alga <i>Ulva linza</i>

Biogeosciences ◽

10.5194/bg-15-3409-2018 ◽

2018 ◽

Vol 15 (11) ◽

pp. 3409-3420 ◽

Cited By ~ 20

Author(s):

Guang Gao ◽

John Beardall ◽

Menglin Bao ◽

Can Wang ◽

Wangwang Ren ◽

...

Keyword(s):

Growth Rate ◽

Ocean Acidification ◽

Nutrient Limitation ◽

Nitrate Reductase Activity ◽

Reductase Activity ◽

Green Tide ◽

Soluble Protein Content ◽

Green Tides ◽

P Limitation ◽

Adult Plants

Abstract. Large-scale green tides have been invading the coastal zones of the western Yellow Sea annually since 2008. Meanwhile, oceans are becoming more acidic due to continuous absorption of anthropogenic carbon dioxide, and intensive seaweed cultivation in Chinese coastal areas is leading to severe regional nutrient limitation. However, little is known about the combined effects of global and local stressors on the eco-physiology of bloom-forming algae. We cultured Ulva linza for 9–16 days under two levels of pCO2 (400 and 1000 µatm) and four treatments of nutrients (nutrient repletion, N limitation, P limitation, and N–P limitation) to investigate the physiological responses of this green tide alga to the combination of ocean acidification and nutrient limitation. For both sporelings and adult plants, elevated pCO2 did not affect the growth rate when cultured under nutrient-replete conditions but reduced it under P limitation; N or P limitations by themselves reduced growth rate. P limitation resulted in a larger inhibition in growth for sporelings compared to adult plants. Sporelings under P limitation did not reach the mature stage after 16 days of culture while those under P repletion became mature by day 11. Elevated pCO2 reduced net photosynthetic rate for all nutrient treatments but increased nitrate reductase activity and soluble protein content under P-replete conditions. N or P limitation reduced nitrate reductase activity and soluble protein content. These findings indicate that ocean acidification and nutrient limitation would synergistically reduce the growth of Ulva species and may thus hinder the occurrence of green tides in a future ocean environment.

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