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

2018 ◽  
Vol 15 (11) ◽  
pp. 3409-3420 ◽  
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.

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

2018 ◽  
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 &amp; 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.

scholarly journals Future CO2-induced ocean acidification enhances resilience of a green tide alga to low-salinity stress

2019 ◽  
Author(s):  
Guang Gao ◽  
Liming Qu ◽  
Tianpeng Xu ◽  
J Grant Burgess ◽  
Xinshu Li ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Salinity Stress ◽  
Reductase Activity ◽  
Photochemical Quenching ◽  
Green Tide ◽  
Negative Effects ◽  
Green Tides ◽  
High Co2 ◽  
Low Salinity ◽  
Whole Life Cycle

AbstractTo understand how Ulva species might respond to salinity stress during future ocean acidification we cultured a green tide alga Ulva linza at various salinities (control salinity, 30 PSU; medium salinity, 20 PSU; low salinity, 10 PSU) and CO2 concentrations (400 and 1000 ppmv) for over 30 days. The results showed that, under the low salinity conditions, the thalli could not complete its whole life cycle. The specific growth rate (SGR) of juvenile thalli decreased significantly with reduced salinity but increased with a rise in CO2. Compared to the control, medium salinity also decreased the SGR of adult thalli at low CO2 but did not affect it at high CO2. Similar patterns were also found in relative electron transport rate (rETR), non-photochemical quenching, saturating irradiance, and Chl b content. Although medium salinity reduced net photosynthetic rate and maximum rETR at each CO2 level, these negative effects were significantly alleviated at high CO2 levels. In addition, nitrate reductase activity was reduced by medium salinity but enhanced by high CO2. These findings indicate that future ocean acidification would enhance U. linza’s tolerance to low salinity stress and may thus facilitate the occurrence of green tides dominated by U. linza.

scholarly journals Future CO2-induced seawater acidification mediates the physiological performance of a green alga Ulva linza in different photoperiods

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7048 ◽  
Author(s):  
Furong Yue ◽  
Guang Gao ◽  
Jing Ma ◽  
Hailong Wu ◽  
Xinshu Li ◽  
...  
Keyword(s):  
Growth Rate ◽  
Ocean Acidification ◽  
Relative Growth Rate ◽  
Green Alga ◽  
Light Period ◽  
Interactive Effects ◽  
Photochemical Quenching ◽  
Green Tide ◽  
Relative Growth ◽  
Ulva Linza

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.

scholarly journals Physiological response of a golden tide alga (<i>Sargassum muticum</i>) to the interaction of ocean acidification and phosphorus enrichment

2017 ◽  
Vol 14 (3) ◽  
pp. 671-681 ◽  
Author(s):  
Zhiguang Xu ◽  
Guang Gao ◽  
Juntian Xu ◽  
Hongyan Wu
Keyword(s):  
Nitrate Reductase ◽  
Ocean Acidification ◽  
Soluble Protein ◽  
Nitrate Reductase Activity ◽  
Nitrate Uptake ◽  
Dark Respiration ◽  
Reductase Activity ◽  
Soluble Carbohydrates ◽  
Promoting Effect ◽  
Nitrate Uptake Rate

Abstract. The development of golden tides is potentially influenced by global change factors, such as ocean acidification and eutrophication, but related studies are very scarce. In this study, we cultured a golden tide alga, Sargasssum muticum, at two levels of pCO2 (400 and 1000 µatm) and phosphate (0.5 and 40 µM) to investigate the interactive effects of elevated pCO2 and phosphate on the physiological properties of the thalli. Higher pCO2 and phosphate (P) levels alone increased the relative growth rate by 41 and 48 %, the net photosynthetic rate by 46 and 55 %, and the soluble carbohydrates by 33 and 62 %, respectively, while the combination of these two levels did not promote growth or soluble carbohydrates further. The higher levels of pCO2 and P alone also enhanced the nitrate uptake rate by 68 and 36 %, the nitrate reductase activity (NRA) by 89 and 39 %, and the soluble protein by 19 and 15 %, respectively. The nitrate uptake rate and soluble protein was further enhanced, although the nitrate reductase activity was reduced when the higher levels of pCO2 and P worked together. The higher pCO2 and higher P levels alone did not affect the dark respiration rate of the thalli, but together they increased it by 32 % compared to the condition of lower pCO2 and lower P. The neutral effect of the higher levels of pCO2 and higher P on growth and soluble carbohydrates, combined with the promoting effect on soluble protein and dark respiration, suggests that more energy was drawn from carbon assimilation to nitrogen assimilation under conditions of higher pCO2 and higher P; this is most likely to act against the higher pCO2 that caused acid–base perturbation via synthesizing H+ transport-related protein. Our results indicate that ocean acidification and eutrophication may not boost golden tide events synergistically, although each one has a promoting effect.

Physiological indicators of nitrogen response in a short rotation sycamore plantation. II. Nitrogen metabolism

1993 ◽  
Vol 71 (6) ◽  
pp. 841-847 ◽  
Author(s):  
Timothy J. Tschaplinski ◽  
Richard J. Norby
Keyword(s):  
Amino Acids ◽  
Growth Rate ◽  
Nitrate Reductase ◽  
Nitrogen Fertilization ◽  
Free Amino ◽  
Nitrate Reductase Activity ◽  
Growth Response ◽  
Reductase Activity ◽  
Growing Season ◽  
Relative Growth

American sycamore (Platanus occidentalis L.) seedlings were grown in the field under different urea–nitrogen fertilization regimes to identify nitrogen variables that characterize the growth response. Treatments included fertilization with 50, 150, and 450 kg N/ha, periodic fertilization (three times during the growing season) at 37.5 kg N/ha, and an unfertilized control. Leaf total nitrogen concentration was a poor indicator of plant growth response to nitrogen fertilization. Salt-extractable protein, nitrate, and free amino acid concentrations all trended upward by the end of the growing season as relative growth rate declined, but treatment differences were minimal. Leaf nitrate reductase activity was consistently higher in fertilized trees before substantial leaf senescence had occurred. When leaf loss was evident, all treatments had high levels of nitrate reductase activity. Aspartic acid and glutamic acid were the most prevalent free amino acids in leaves, whereas concentrations of amine-rich amino acids were low. Although several nitrogen variables, including foliar asparagine and glycine concentrations, were positively correlated with relative growth rate (r ≥ 0.7), no single variable closely reflected treatment differences in growth response. Key words: amino acids, nitrogen, nitrate reductase, sycamore.

scholarly journals Physiological response of a golden tide alga (<i>Sargassum muticum</i>) to the interaction of ocean acidification and phosphorus enrichment

2016 ◽  
Author(s):  
Zhiguang Xu ◽  
Guang Gao ◽  
Juntian Xu ◽  
Hongyan Wu
Keyword(s):  
Ocean Acidification ◽  
Soluble Protein ◽  
Nitrate Reductase Activity ◽  
Nitrate Uptake ◽  
Dark Respiration ◽  
Reductase Activity ◽  
Soluble Carbohydrates ◽  
Promoting Effect ◽  
Pco2 Level ◽  
Nitrate Uptake Rate

Abstract. The evolvement of golden tides would be influenced by global change factors, such as ocean acidification and eutrophication, but the related studies are very scarce. In this study, we cultured a golden tide alga, Sargasssum muticum, at two levels of pCO2 (400, 1000 µatm) and phosphate (0.5 µM, 40 µM) conditions to investigate the interactive effects of elevated pCO2 and phosphate on physiological properties of the thalli. The higher pCO2 level and phosphate (P) level alone increased the relative growth rate by 40.82 % and 47.78 %, net photosynthetic rate by 46.34 % and 55.16 %, soluble carbohydrates by 32.78 % and 61.83 % respectively whilst the combination of these two levels did not promote growth or soluble carbohydrates further. The higher levels of pCO2 and P alone also enhanced the nitrate uptake rate by 68.27 % and 35.89 %, nitrate reductase activity by 89.08 % and 39.31 %, and soluble protein by 19.05 % and 15.13 % respectively. The nitrate uptake rate and soluble protein was further enhanced although the nitrate reductase activity was reduced when the higher levels of pCO2 and P worked together. The higher pCO2 level and higher P level alone did not affect the dark respiration rate of thalli but they together increased it by 32.30 % compared to the condition of the lower pCO2 and lower P. The mute effect of the higher level of pCO2 and higher P on growth, soluble carbohydrates, combined with the promoting effect of it on soluble protein and dark respiration, suggests more energy was drawn from carbon assimilation to nitrogen assimilation at the condition of higher pCO2 and higher P, probably to act against the higher pCO2 caused acid-base perturbation via synthesizing H+ transport-related protein. Our results indicate ocean acidification and eutrophication may not boost the gold tides events synergistically although each of them alone has a promoting effect.

Comparative behaviour of seedlings of sorghum and some tropical legumes in relation to leaf expansion and growth

1985 ◽  
Vol 104 (3) ◽  
pp. 625-630 ◽  
Author(s):  
R. K. Chopra ◽  
K. R. Koundal ◽  
Madhu Kansal
Keyword(s):  
Nitrate Reductase ◽  
Leaf Area ◽  
Growth Rates ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Soluble Protein Content ◽  
Leaf Area Expansion ◽  
Area Expansion ◽  
Area Development ◽  
Leaf Area Development

SummaryGrowth rates were compared of pigeonpea (Cajanus cajan), moth bean (Vigna aconitifolia), mung bean (Vigna radiata) and sorghum seedlings aged 2–5 weeks. The seedling growth rates were analysed in relation to leaf area development, net photosynthetic rate, nitrogen accumulation, nitrate reductase activity, and soluble protein content. Growth rates were highest in sorghum and lowest in C. cajan. Leaf area development was very fast in sorghum and very slow in C. cajan. Net photosynthetic rate of sorghum leaves was double that observed for the legume leaves. No significant difference was observed in nitrate reductase activity, nitrogen percentage or soluble protein content between sorghum and the legumes. In sorghum, early investment of assimilates into leaf development ensured a higher assimilation of carbon and nitrogen per plant. In the legumes, slow development of leaf area coupled with low photosynthetic rates probably resulted in slow growth of the seedlings. In the legume seedlings, vigour was related to the rates of leaf area expansion. Leaf area expansion rates were not related to the nitrogen status of the leaf in the species examined.

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