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CO2和DIP对浒苔幼苗生长及光合特性的影响
王津果, 盛杨杰, 王续昆, 倪嘉璇, 武卉, 刘卫国, 周伟
海洋学研究 ›› 2023, Vol. 41 ›› Issue (2) : 114-122.
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CO2和DIP对浒苔幼苗生长及光合特性的影响
Effects of CO2 and dissolved inorganic phosphate on the growth and photosynthetic performance of Ulva prolifera seedlings
绿藻微观繁殖体具有快速生长和繁殖的特性,是绿潮暴发重要的种子来源。以浒苔(Ulva prolifera)微观繁殖体发育而来的幼苗为实验材料,研究不同CO2水平(400 μatm和1 000 μatm)和无机磷酸盐(dissolved inorganic phoshphate, DIP)浓度(0.32 μmol·L-1、3.62 μmol·L-1、36.2 μmol·L-1)下单因子及双因子交互作用对其生长和光合生理指标的影响。相对生长速率(RGR)、净光合速率(Pn)和呼吸速率(Rd)等生长指标显示:CO2对RGR和Pn有显著影响(p<0.05);DIP对RGR、Pn和Rd均有显著影响(p<0.05),随着DIP增加,RGR和Pn升高,Rd降低;双因子交互作用对3个指标影响均不显著(p>0.05)。最大相对光合电子传递速率(rETRmax)、饱和光强(Ek)、有效光合量子产率[Y(II)]、光能利用效率(α)等荧光参数显示:CO2对rETRmax、Ek影响显著(p<0.05); DIP浓度升高使Y(II)、rETRmax、α和Ek显著提高(p<0.05);双因子交互作用对rETRmax和Y(II)影响显著(p<0.05),对α和Ek影响不显著(p>0.05)。Chl a、Chl b和类胡萝卜素等色素指标显示:CO2、DIP以及交互作用对3个指标影响均显著(p<0.05),高CO2水平明显抑制色素的合成,并且随着DIP浓度升高,抑制程度加剧;3个指标与DIP均呈正相关。研究表明,高CO2水平和高DIP浓度会明显促进浒苔幼苗的生长,为绿潮的暴发提供了有利条件。
Micropropagules with rapid growth and reproduction are an important seed sources for the early outbreak of the green tide. In this study, the micropropagule seedlings of Ulva prolifera were collected as experimental materials, and two CO2 levels (LC, 400 μatm; HC, 1 000 μatm) and three dissolved inorganic phoshphate (DIP) concentrations (LP, 0.32 μmol/L; MP, 3.62 μmol/L; HP, 36.2 μmol/L) were set to analyze the effects of CO2, DIP and their interaction on its growth and photophysiological performance. The results of the growth indexes including relative growth rate (RGR), net photosynthetic rate (Pn) and respiration rate (Rd) showed that CO2 significantly affected on the RGR and Pn (p<0.05). DIP significantly affected on the RGR, Pn and Rd (p<0.05). Specifically, RGR and Pn were significantly positively correlated with DIP concentration (p<0.05), while Rd was significantly negatively correlated with DIP concentration (p<0.05). However, their interaction had no significant effect on RGR, Pn and Rd (p>0.05). The results of fluorescence parameters including effective quantum yield [Y(II)], maximum relative electron transfer rate (rETRmax), saturation light intensity (Ek) and light utilization efficiency indicated (α) reveal that CO2 significantly affected on the rETRmax and Ek (p<0.05), but had no significant effect on the Y(II) and α (p>0.05). DIP significantly affected all the fluorescence parameters, which were significantly promoted by the DIP concentration increase (p<0.05). And their interaction had significant effect on the rETRmax and Y(II) (p<0.05), but had no significant effect on the Ek and α (p>0.05). Pigments of Chl a, Chl b and carotenoid results showed that CO2, DIP and their interaction significantly affected the pigments contents (p<0.05). Evelated-CO2 significantly inhibited pigment synthesis (p<0.05), and the inhibitory effect was enhanced with the increasing of DIP concentration. The pigments contents were significantly positively correlated with DIP concentration (p<0.05). Our findings suggested that evelated-CO2 and higher DIP concentration obviously promoted the growth of U.prolifera seedlings, which was favorable for the green tide outbreak.
Ulva prolifera / micropropagules / CO2 / dissolved inorganic phoshphate / growth
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Using inorganic carbon measurements from an international survey effort in the 1990s and a tracer-based separation technique, we estimate a global oceanic anthropogenic carbon dioxide (CO2) sink for the period from 1800 to 1994 of 118 +/- 19 petagrams of carbon. The oceanic sink accounts for approximately 48% of the total fossil-fuel and cement-manufacturing emissions, implying that the terrestrial biosphere was a net source of CO2 to the atmosphere of about 39 +/- 28 petagrams of carbon for this period. The current fraction of total anthropogenic CO2 emissions stored in the ocean appears to be about one-third of the long-term potential.
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. 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.\n
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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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The incidence and severity of extraordinary macroalgae blooms (green tides) are increasing. Here, climate change (ocean warming and acidification) impacts on life history and biochemical responses of a causative green tide species, Ulva rigida, were investigated under combinations of pH (7.95, 7.55, corresponding to lower and higher pCO), temperature (14, 18°C) and nitrate availability (6 and 150μmolL). The higher temperature accelerated the onset and magnitude of gamete settlement. Any two factor combination promoted germination and accelerated growth in young plants. The higher temperature increased reproduction, which increased further in combination with elevated pCO or nitrate. Reproductive success was highest (64.4±5.1%) when the upper limits of all three variables were combined. Biochemically, more protein and lipid but less carbohydrate were synthesized under higher temperature and nitrate conditions. These results suggest that climate change may cause more severe green tides, particularly when eutrophication cannot be effectively controlled.Copyright © 2016 Elsevier Ltd. All rights reserved.
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. 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.
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Ocean acidification and eutrophication are two major environmental issues affecting kelp mariculture. In this study, the growth, photosynthesis, and biochemical compositions of adult sporophytes of Saccharina japonica were evaluated at different levels of pCO2 (400 and 800 µatm) and nutrients (nutrient-enriched and non-enriched seawater). The relative growth rate (RGR), net photosynthetic rate, and all tested biochemical contents (including chlorophyll (Chl) a, Chl c, soluble carbohydrates, and soluble proteins) were significantly lower at 800 µatm than at 400 µatm pCO2. The RGR and the contents of Chl a and soluble proteins were significantly higher under nutrient-enriched conditions than under non-enriched conditions. Moreover, the negative effects of the elevated pCO2 level on the RGR, net photosynthetic rate, Chl c and the soluble carbohydrates and proteins contents were synergized by the elevated nutrient availability. These results implied that increased pCO2could suppress the growth and biochemical composition of adult sporophytes of S. japonica. The interactive effects of ocean acidification and eutrophication constitute a great threat to the cultivation of S. japonica due to growth inhibition and a reduction in quality.
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