Photosynthesis,growth and survival of the Mediterranean seagrass Posidonia oceanica in response to simulated salinity increases in a laboratory mesocosm system     

Lázaro Marín-Guirao  José M. Sandoval-Gil  Juan M. Ruíz  José L. Sánchez-Lizaso 《Estuarine, Coastal and Shelf Science》2011

This study aims to examine the effect of increased salinity on the photosynthetic activity of the Mediterranean seagrass Posidonia oceanica in a laboratory mesocosm system. To do this, large rhizome fragments were transplanted in a mesocosm laboratory system and maintained at 37 (ambient salinity, control treatment), 39, 41 and 43 (hypersaline treatments) for 47 days. Pigment content, light absorption, photosynthetic characteristics (derived from P vs. E curves and fluorescence parameters), and shoot size, growth rates and net shoot change were determined at the end of the experimental period. Both net and gross photosynthetic rates of plants under hypersaline conditions were significantly reduced, with rates some 25–33% and 13–20% lower than in control plants. The pigment content (Chla, Chlb, Chlb:Chla molar ratio, total carotenoids and carotenoids:Chla ratio), leaf absorptance and maximum quantum yield of PSII (F_v/F_m) of control plants showed little or no changes under hypersaline conditions, which suggests that alterations to the capacity of the photosynthetic apparatus to capture and process light were not responsible for the reduced photosynthetic rates. In contrast, dark respiration rates increased substantially, with mean values up to 98% higher than in control leaves. These results suggest that the respiratory demands of the osmoregulatory process are likely to be responsible for the observed decrease in photosynthetic rates, although alterations to photosynthetic carbon assimilation and reduction could also be involved. As a consequence, leaf carbon balance was considerably impaired and leaf growth rates decreased as salinity increased above the ambient (control) salinity. No significant differences were found in the percentage of net shoot change, but mean values were clearly negative at salinity levels of 41 and 43. Results presented here indicate that photosynthesis of P. oceanica is highly sensitive to hypersaline stress and that it likely account for the decline in leaf growth and shoot survival reported in this and previous studies in response to even small increments of the ambient salinity.  相似文献   

不同氮磷水平对缘管浒苔生长及光合作用的影响   总被引：4，自引：0，他引：4  

朱明  刘兆普  徐军田  茅云翔  姚东瑞 《海洋湖沼通报》2011,(3):57-61

近岸海域的富营养化是被广泛关注的重要海洋生态环境问题,其中N和P是富营养化过程主要的2种营养盐.本实验旨在探讨N和P对缘管浒苔的生长、光合作用以及可溶性蛋白含量的影响.结果表明:添加N和P都显著增加藻体的光合作用速率、可溶性蛋白含量,最终显著提高藻体的相对生长率.缘管浒苔对N和P的利用可以在一定范围内相互弥补.这表明缘...  相似文献   

厦门大嶝岛潮间带底栖微藻叶绿素荧光对温度和光照变化的响应     

穆文华  谢聿原  黄邦钦 《台湾海峡》2014,(3):318-325

采用PAM叶绿素荧光技术,于2013年5月在厦门大嶝岛潮间带,对不同底质类型（泥质、泥砂质和砂质）底栖微藻的光合作用特征进行了初步研究.结果显示：底栖微藻的光合系统II最大光量子效率（Fv/Fm）呈泥质（0.33）〉泥砂质（0.28）〉砂质（0.01）;底栖微藻叶绿素a含量亦呈上述变化趋势.不同温度（15-35℃）和不同光照透射率（0-100%）的短期（0.5-2.0 h）培养实验表明,底栖微藻光合作用的最适温度（27℃左右）接近于环境温度,体现了其对生长环境的适应;过高的温度（35℃及以上）会抑制光合作用活性,进而限制其生长;此外,光照实验表明底栖微藻可通过自身的运动和变化来适应光照强度的变化,不同底质类型可能存在不同的光适应策略.  相似文献   

Coupling the terrestrial hydrology model with biogeochemistry to the integrated LAND surface model: Amazon Basin applications     

Aline Anderson de Castro  Luz Adriana Cuartas  Michael T. Coe  Celso Von Randow  Andrea Castanho  Alex Ovando 《水文科学杂志》2013,58(13-14):1954-1966

ABSTRACT

We coupled the hydrologic routing and flood dynamics model Terrestrial Hydrology Model with Biogeochemistry (THMB) to the Integrated LAND Surface Model (INLAND) and compared simulations of the discharge and flood extent area against gauge station and satellite-based information in the Amazon Basin. The coupled model represents well the seasonality of the flooding and discharge, but underestimates both of them. This can be related to an already discussed underestimate of the precipitation in the east of the Andes Mountains. A photosynthesis limitation on the flooded area was also included, showing changes in plant productivity and reduction in vegetation carbon stocks. Despite its limitations, the model proves to be a valuable tool for studies of the hydrological cycle and flood dynamics response to climate change projections, allowing it to be used to represent the feedbacks between continental surface water cycle and vegetation.  相似文献   

海水水淹下海滨木槿和蜡杨梅幼苗叶片的光合作用及其影响因子研究   总被引：1，自引：0，他引：1  

顾沈华  虞木奎  杨杰  徐建兵  孙海菁  吴统贵 《湿地科学》2013,11(3)

滩涂消浪林是中国沿海防护林体系的前沿阵地,在防浪促淤、保岸护堤和防御海洋自然灾害等方面具有重要的作用.以中亚热带泥质海岸的两种消浪树种海滨木槿(Hibiscus hamabo)和蜡杨梅(Myrica cerifera)一年生幼苗为实验材料,根据半日潮滩涂的淹水时间和淹水深度,设计5种实验处理,即在每个半日潮中,两个树种的平均淹水时间和淹水深度分别为lh和15 cm(处理1)、2h和25 cm(处理2)、3h和35 cm(处理3)、4h和45 cm (处理4)以及无水淹的对照处理(用淡水正常浇灌).在模拟海水水淹胁迫下的70d中,研究两树种幼苗向阳面叶片的光合作用日变化及其与叶片其他生理生态因子的关系,揭示其主要影响因子.结果表明,各处理下,海滨木槿幼苗叶片净光合速率(Pn)日变化(6:00～18:00)曲线为单峰曲线;在水深较浅、时间较短的水淹处理下,海滨木槿幼苗叶片Pn主要受光合有效辐射(PAR)影响,在水深较深、时间较长的水淹处理下,则主要受叶片气孔导度(G)和胞间CO2浓度(Ci)的影响;在水淹初、中期,蜡杨梅幼苗叶片Pn日变化曲线为双峰曲线,但在水淹后期,其为单峰曲线;在水深较浅、时间较短的水淹处理下,蜡杨梅幼苗叶片Pn主要受PAR和Gs影响,而在水深较深、时间较长的水淹处理下,其主要受Ci和饱和水蒸汽压亏缺影响.  相似文献   

基于蛋白组学分析杜氏盐藻对不同浓度CO₂的响应     

蔡学花  顾文辉  李元翔  王广策 《海洋科学》2018,42(9):98-106

用气体混合仪设置不同的CO_2浓度处理组,测定了杜氏盐藻(Dunaliella salina)细胞密度、碳酸酐酶活性、甘油含量等生理指标,结合蛋白质组学分析方法,比较了不同CO_2浓度下细胞内主要代谢路径蛋白表达的差异。结果表明:在一定范围内,随着CO_2浓度的升高,杜氏盐藻的生理活性及光合活性提高;而CO_2浓度过高对盐藻生长呈抑制作用; 3%CO_2浓度最适于本实验杜氏盐藻藻株的生长。随着CO_2浓度的升高,胞外碳酸酐酶活性下降。低浓度的CO_2有利于β-胡萝卜素的积累,且光系统Ⅱ(PSⅡ)光合活性在CO_2浓度0.03%～3%范围内上升, CO_2浓度达9%时降低,与光合作用相关蛋白的表达趋势接近。上述结果说明杜氏盐藻可能通过调节光合作用中叶绿素等捕光色素的合成及相关蛋白的表达笼统,以响应CO_2浓度的变化;而过高浓度的CO_2可对细胞产生氧化损害,引起热激蛋白和超氧化物歧化酶等蛋白含量的上调以应对氧化胁迫。  相似文献   

植被大气间能量储存分项对能量闭合率的影响分析     

田志伟  王维真  王介民 《冰川冻土》2016,38(3):794-803

植被大气间能量储存分项对能量闭合的影响在地表能量平衡研究中有重要意义。以张掖市盈科灌区玉米农田为研究区,在采用TDEC（Thermal Diffusion Equation+Correction）方法修正土壤热通量的基础上,分析了植被大气间能量储存分项对能量闭合率的影响。结果表明：能量储存分项对于能量闭合率具有一定的提升作用,平均提升幅度约为5.18%。能量储存分项对能量闭合率的影响与有效能量（R_n-G）相关。各能量储存分项对能量闭合率的贡献从大到小依次为：光合作用 >植被冠层热储存 >空气热储存 >空气湿度变化≈露水焓变,其中后两项量级极小,可在相关研究中忽略。量级较大的前三项能量分项具有明显的单峰日变化趋势,其中光合作用项相对另两分项在时间上有所滞后。此外,不同天气条件下（如有云和无云）能量储存分项对于能量闭合率的影响不同,有云时其影响相对较大。  相似文献   

The photokinetics of thermo‐tolerance in Symbiodinium     

Alison Jones  Ray Berkelmans 《Marine Ecology》2012,33(4):490-498

There is currently much debate about the ecological advantages for reef corals of hosting multiple types of the symbiotic dinoflagellate Symbiodinium. Amongst these is their apparent capacity to tolerate higher than normal water temperatures. There is strong photokinetic evidence that the trait of heat‐tolerance in plants is accompanied by energetic tradeoffs but little such evidence yet exists for corals. We use rapid light curves (RLCs) to investigate the photokinetic basis for thermo‐tolerance in the reef coral Acropora millepora with symbionts of contrasting thermal tolerance for which there are measured differences in energetics. Our results show that under non‐stressful temperatures, corals with heat‐tolerant type D Symbiodinium had a 41% lower maximum relative electron transport rate (rETRmax) and lower light absorption efficiency (α) due to lower cell Chl a content compared with corals with heat‐sensitive type C2 symbionts. Our results provide support for a photokinetic link between heat tolerance and deficits in holobiont (coral + symbiont) growth, lipid stores and reproduction. Reduced electron transport rate and light absorption capacity may be genotype‐specific attributes that enable clade D symbionts and their cnidarian hosts to cope with temperature stress but they inherently influence the photosynthetic function of the symbionts and thus have negative downstream effects on the coral.  相似文献   

Micronutrient effects on cyanobacterial growth and physiology     

John G. Rueter  Richard R. Petersen 《新西兰海洋与淡水研究杂志》2013,47(3):435-445

Trace metals play crucial roles in the carbon and nitrogen metabolism of cyanobacteria. Physiological responses to metal limitation and toxicity in culture have shown that iron is important for photosynthesis and energy distribution in the cell while both iron and molybdenum are biochemically involved in nitrate reduction and nitrogen fixation. Nitrogen fixation is also relatively sensitive to copper toxicity. Consequently, factors that affect the supply rate, chemical speciation, or the recycling of trace metals can alter patterns of primary productivity and nitrogen metabolism. Overall, three trace metal dependent processes may contribute towards dominance: efficient use of limiting light, nitrogen fixation, and production of extracellular iron binding compounds.  相似文献   

基于遥感沿海湿地植被生产力估算研究     

相栋  王云峰  栾青  靳宁  赵永强  田国珍 《山西气象》2010,(4):13-17

植被净第一性生产力是评价地表植被状况的重要指标之一,对分析和评价全球以及区域生态环境、碳循环等变化具有重要作用.植被净第一生产力的研究方法很多,本文主要运用TM影像近红外和红光通道组成的标准化差植被指数（NDVI）,借助CASA模型机理以及气象学方法,建立盐城区域净第一性生产力（NPP）遥感估算模型,并以核心区-丹顶鹤自然保护区湿地为应用案例,分析了核心区2005年间8月份净第一性生产力的变化.分析结果表明,研究区8月份的湿地各种植被NPP分别为：人工芦苇和盐蒿为1184.863266 g/m2,芦苇为1083.435262g/m2,米草为822.766878g/m2.若以NPP为衡量标准,人工芦苇和盐蒿的净第一性生产力最高.  相似文献