Effects of Temperature and Light on Growth Rate and Photosynthetic Characteristics of Sargassum horneri

The changing environmental factors exerted great influences on coastal macroalgal communities.To study the responses of the brown seaweed Sargassum horneri to temperature and light,S.horneri was cultured under three temperatures(20,25 and 30℃)and three light intensities(30,60,and 120μmol photons m-2 s-1)for seven days.The growth rate,chlorophyll a(Chl a)and carotenoids(Car)contents,chlorophyll fluorescence,and photosynthetic oxygen evolution rate were measured.The results show that the highest relative growth rate(RGR),maximal electron transport rate(rETRmax);the net photosynthetic rate(Pn)were observed at the lowest temperature(20℃)and highest light intensity(120μmol photons m-2 s-1);and the RGR and Pn were significantly inhibited by the highest temperature(30℃),especially at the lowest light intensity(30μmol photons m-2 s-1)(P<0.05).Additionally,the highest light intensity enhanced the non-photochemical quenching(NPQ)even under the highest temperature(30℃),indicating that the higher light intensity could induce photo-protection reaction of thalli.These results suggest that the higher temperature and lower light intensity exerted negative influences on S.horneri.     

温度、光照对小环藻生长和叶绿素a含量的影响

用单因子和正交实验方法研究了温度和光照对小环藻生长和叶绿素a含量的影响。结果表明,温度对小环藻生长和叶绿素a含量有极显著影响(P<0.01),当温度在30~40℃时比增长率和叶绿素a含量分别为0.37~0.38 d-1和1 084.4~1 214.2μg.L-1,均显著高于其他温度组。光照对小环藻生长和叶绿素a含量有极显著影响(P<0.01),当光照强度从29.25~146.26μmol.m-2.s-1时比增长率最高,为0.30~0.32 d-1;而叶绿素a含量则在9.75~58.50μmol.m-2.s-1时最高,达709.7~731.8μg.L-1,极显著高于其他照度组。正交实验结果表明:在35℃、87.75μmol.m-2.s-1条件下种群增长最快,比增长率为0.4402 d-1;在30℃、29.25μmol.m-2.s-1时,叶绿素a含量最高,为1 746.6μg.L-1。     

不同光合光子照度LED蓝光对湛江等鞭金藻生长及色素含量的影响

在实验室水温26℃、盐度31条件下,研究LED蓝光(波长450 nm)不同光合光子照度对湛江等鞭金藻(Isochrysis zhanjiangensis)细胞生长速率及色素含量的影响,结果表明,不同光合光子照度的梯度实验组藻细胞生长速率及色素含量差异具统计学意义(P0.05),在66~171μmol·m~(-2)·s~(-1)范围内,细胞相对生长速率随光子照度的增加而加快,在171μmol·m~(-2)·s~(-1)时达到最大值0.48个·d~(-1),在192μmol·m~(-2)·s~(-1)时出现下降;藻细胞的7 d色素累积量在171μmol·m~(-2)·s~(-1)下其叶绿素a、叶绿素c、类胡萝卜素及总色素的累积量均达到最大,分别是3 340.16、1 176.23、1 566.43及6 082.82μg·L-1,与其他组差异具统计学意义(P0.05)。蓝光LED下湛江等鞭金藻细胞光合作用的最佳光合光子照度约为171μmol·m~(-2)·s~(-1)。     

Effects of temperature and irradiance on early development of Chondrus ocellatus Holm(Gigartinaceae, Rhodophyta)

Chondrus is a type of commercially produced red seaweed that widely used for food and carrageen extraction. Although the natural life history of the alga had been well understood, the factors influencing development of the tetraspore and carpospore remain poorly understood. In the perspective of seedling resources, the regulation of early development is crucial for the seedling nursing; therefore, it is necessary to understand the physiological influences during its early development. In this study, we studied the effects of temperature and irradiance on the early development of Chondrus ocellatus Holm under laboratory conditions. The released tetraspores and carpospores were cultivated at different temperatures (10–28°C) and irradiances (10, 60 μmol photons m-2s-1) with a photoperiod of 12L:12D. The results indicate that both tetraspores and carpospores are tolerant to temperatures of 10–25°C, and have the highest relative growth rate at 20°C. Irradiance variances influenced the growth of the discoid crusts, and the influence was more significant with increasing temperature; 60 μmol photons m-2s-1 was more suitable than 10 μmol photons m-2s-1. The optimum temperature and irradiance for the development of seedlings was 20°C and 60 μmol photons m-2s-1, respectively.     

盐度对半叶马尾藻幼苗生长及光合色素合成的影响

在温度22±0.5℃、光照强度100μmol·m-2·s-1的光照培养箱中,以8组不同盐度培养半叶马尾藻(Sargassum hemiphyllum)幼苗(2~3 g/株),研究不同盐度对其生长发育和光合色素合成的影响。结果表明:半叶马尾藻幼苗适合存活和生长的盐度为24.84~35.28,在该盐度范围内幼苗均可正常存活和生长;幼苗最适生长盐度为30.06,质量增长率达到最大,光合色素含量达到最高;24.84~35.28中,幼苗更适合于在高盐端生长。     

Distribution and Cycling of Carbon Monoxide in the East China Sea and the Marine Atmosphere in Autumn

Carbon monoxide(CO) concentrations, sea-to-air fluxes and microbial consumption rate constants, along with atmospheric CO mixing ratios, were measured in the East China Sea(ECS) in autumn. Atmospheric CO mixing ratios varied from 96 to 256 ppbv, with an average of 146 ppbv(SD = 54 ppbv, n = 31). Overall, the atmospheric CO concentrations displayed a decreasing trend from inshore to offshore stations. The surface water CO concentrations in the investigated area ranged from 0.24 to 6.12 nmol L~(-1), with an average of 1.68 nmol L~(-1)(SD = 1.50 nmol L~(-1), n = 31). The surface water CO concentrations were affected significantly by sunlight. Vertical profiles showed that CO concentrations declined rapidly with depth, with the maximum appearing in the surface water. The surface CO concentrations were oversaturated, with the saturation factors ranging from 1.4 to 56.9, suggesting that the ECS was a net source of atmospheric CO. The sea-to-air fluxes of CO in the ECS ranged from 0.06 to 11.31 μmol m~(-2) d~(-1), with an average of 2.90 μmol m~(-2) d~(-1)(SD = 2.95μmol m~(-2) d~(-1), n = 31). In the incubation experiments, CO concentrations decreased exponentially with incubation time and the processes conformed to the first order reaction characteristics. The microbial CO consumption rate constants in the surface water(KCO) ranged from 0.063 to 0.22 h~(-1), with an average of 0.12 h~(-1)(SD = 0.062 h~(-1), n = 6). A negative correlation between KCO and salinity was observed in the present study.     

半叶马尾藻对N、P吸收速率的初步研究

在实验室条件下研究半叶马尾藻对不同浓度N、P以及不同化合态N的吸收速率。结果显示:不同浓度N、P下,半叶马尾藻对N、P的吸收速率差异有统计学意义(P0.05);半叶马尾藻对N、P的吸收速率随N、P浓度的升高而增加,最大吸收速率出现在N为200μmol/L、P为20μmol/L时,分别为2.397和0.229μmol·g-1·h-1;不同氮磷比条件下,半叶马尾藻对N、P的最大吸收速率出现在氮磷比为10时,在氮磷比为1~30范围内,氮磷比对半叶马尾藻吸收N、P速率的影响有统计学意义(P0.05);不同化合态N对半叶马尾藻吸收N、P速率的影响有统计学意义(P0.05),当NH4+-N和NO3--N共存时,半叶马尾藻对这2种化合态氮可同时吸收利用,各处理组间,对总无机N的吸收速率差异有统计学意义(P0.05),在c(NO3--N)/c(NH4+-N)为2∶1和1∶2处有两个峰值,分别为2.036、1.862μmol·g-1·h-1,对P的最大吸收速率均出现在c(NO3--N)/c(NH4+-N)值为2∶1时,为0.206μmol·g-1·h-1。因此,在粤西沿海半叶马尾藻在消除养殖水域营养盐、防治海水富营养化方面有很大优势。     

不同环境条件下无菌和自然带菌波吉卵囊藻生长的比较

比较不同温度、光照及海水相对密度条件下无菌与自然带菌波吉卵囊藻(Oocystis borgei)生长的差异。结果表明:在20℃时,无菌藻的比增长率(μ)和叶绿素a(Chla)含量分别为0.398d-1和0.117mg/L,均显著高于带菌藻(P<0.05),在28和35℃时,无菌藻和带菌藻生长无显著性差异(P>0.05);在照度为16μmol·m-2·s-1时,无菌藻平均比增长率μ和Chla含量分别为0.345d-1和0.123mg/L,均显著高于带菌藻(P<0.05),在照度为39和88μmol·m-2·s-1条件下,无菌藻和带菌藻生长无显著性差异(P>0.05);在海水密度为1.007、1.020和1.030g/mL时,无菌藻和带菌藻的生长均无显著性差异(P>0.05),μ和Chla含量分别为0.325～0.374d-1和0.085～0.133mg/L。     

Early development of Costaria costata (C. Agardh) Saunders and cultivation trials

Costaria costata(C.Agardh) Saunders is one of common kelps distributed in many coastal areas worldwide;however,in China,no reports have been made on cultivation of the genus.To investigate potential cultivation of the species in the northern part of China,trials on isolation and preservation of the gametophytes were conducted using C.costata from Korea;growth and development of the gametophytes were observed.We showed that at 10±1°C,60 μmol m-2s-1 and 12:12 h(L:D),freshly released zoospores settled down wit...     

k阶卡米歇尔数的判定

k阶卡米歇尔数,在k=2,3时有简单的判定条件.给出了k≥4时类似的判定条件.利用孙子定理,通过构造Zn上的首一k次不可约多项式的方法,证明了k≥4时的充分条件也是必要条件,即n∈Ck[k≥4],如果k=2m,m≥2,则pm-1nk-1,q2m-1-1︱nk-1;如果k=2m+1,m≥2,则pm-1︱nk-1,pm+1-1︱nk-1;q2m-1nk-1.从而得出︱n∈Ck[k≥4]的两个充分必要条件.     

不同附着基质对长茎葡萄蕨藻生长及附着效果的影响

【目的】探索不同附着基质对长茎葡萄蕨藻(Caulerpalentillifera)直立枝生长及藻体附着效果的影响。【方法】对长茎葡萄蕨藻直立枝以垂直砂埋、水平砂埋、塑料网网夹、尼龙网网夹及无附着基质(对照组)五种附着方式进行实验,探究长茎葡萄蕨藻直立枝的生长、附着能力、光合特性参数及营养含量的变化。【结果】垂直砂埋处理下,藻体的新生直立枝质量、质量长度比及球状小枝的直径与其他各组相比最优(P <0.05),分别是0.313 3 g、0.086 6 g/mm和1.67 mm,是对照组的7.38、9.62、1.67倍;水平砂埋与对照组相比,藻体附着能力有显著增强(P <0.05),假根数为26,长度为30.77 mm及假根附着砂砾质量为0.566 0 g;除对照组外,各组最大光能转化效率(Fv/Fm)和实际光化学效率Y(II)值呈先下降后上升趋势,24 h后垂直沙埋藻体Fv/Fm和Y(II)最快恢复原始水平,为0.856μmol·m~(-2)·s~(-1)和0.851μmol·m~(-2)·s~(-1),显著高于其余组(P <0.05);垂直砂埋与水平砂埋处理后的藻体,其可溶性糖含量分别比对照组显著降低34.24%和33.93%(P<0.05),而网夹处理后,没有显著差异(P> 0.05)。垂直砂埋处理对藻体总蛋白含量增加有显著促进作用,是对照组的1.26倍(P <0.05)。【结论】长茎葡萄蕨藻直立枝以垂直砂埋附着方式生长最佳,以水平砂埋附着方式附着更牢固。     

Responses of Yellow Sea Cold Water Mass to Typhoon Bolaven

A two-month seabed-mounted observation(YSG1 area) was carried out in the western Yellow Sea Cold Water Mass(YSCWM) using an RDI-300 K acoustic Doppler current profiler(ADCP) placed at a water depth of 38 m in late summer, 2012. On August 2012, Typhoon Bolaven passed east of YSG1 with a maximum wind speed of 20 m s-1. The water depth, bottom temperature, and profile current velocities(including u, v and w components) were measured, and the results showed that the typhoon could induce horizontal current with speed greater than 70 cm s-1 in the water column, which is especially rare at below 20 meters above bottom(mab). The deepening velocity shear layer had an intense shear velocity of around 10 cm s-1 m-1, which indicated the deepening of the upper mixed layer. In the upper water column(above 20 mab), westward de-tide current with velocity greater than 30 cm s-1 was generated with the typhoon's onshore surge, and the direction of current movement shifted to become southward. In the lower water column, a possible pattern of eastward compensation current and delayed typhoon-driven current was demonstrated. During the typhoon, bottom temperature variation was changed into diurnal pattern because of the combined influence of typhoon and tidal current. The passage of Bolaven greatly intensified local sediment resuspension in the bottom layer. In addition, low-density particles constituted the suspended particulate matter(SPM) around 10 mab, which may be transported from the central South Yellow Sea by the typhoon. Overall, the intensive external force of the Typhoon Bolaven did not completely destroy the local thermocline, and most re-suspended sediments during the typhoon were restricted within the YSCWM.     

Effect of temperature and irradiance on the growth and reproduction of Enteromorpha prolifera J. Ag. （Chlorophycophyta, Chlorophyceae）

Effect of temperature and irradiance on growth and reproduction of Enteromorpha prolifera that bloomed offshore along the Qingdao coast in summer 2008, was studied. It was showed that E. prolifera propagated mainly asexually with specific growth rate (SGR) of 10.47 at 25°C/40 μmol m-2s-1. Under this condition, gametes with two flagellate formed and released in 5 days. At the beginning of the development, the unicell gamete divided into two cells with heteropolarity, and then the apical cell developed into thalli primordial cells, whereas the basal cell developed into rhizoid primordial cells. In 8-day culture, the monoplast gamete developed into juvenile germling of 240 μm in length. Unreleased gametes can develop directly within the alga body. E. prolifera could either reproduce through lateral branching or fragmenting except apomixis revealed by Microscopic observation. On aged tissue of E. prolifera, although the degraded pigments partially remained in faded algal filaments, numerous vegetative ceils could still divide actively in the algal tissues.     

Formation and early development of tetraspores of Polysiphonia urceolata (Rhodomelaceae, Rhodophyta)

Polysiphonia urceolata is one type of potential commercial red seaweeds used for breeding and cultivation, because of its significant biochemical and biomedical application. However, the information of breeding and seedling incubation for cultivation is limited, especially the early development. In this study, tetrasporohyte and gametophyte of P. urceolata were taken as the study materials in Huiquan Bay, Qingdao, China. The cleaned and sterilized tetrasporophytes and gametophytes were pre-cultured in sterilized seawater, then nurtured at 18℃, 25 μmol photons m-2 s-1 in 12:12 h (light:dark) photoperiod. Continuous observation under microscope showed that the early development consists of bipolar division stage and seedling stage. In the division stage, tetraspores germinate into bipolar sporelings that further differentiate into a colorless rhizoidal portion and a lightly pigmented upright shoot. The lightly pigmented rhizoidal cell develops to a rhizoid and the larger pigmented cell transforms to an erect axis. In the seedling stage, several quasi-protuberances appear on the erect axis and form juvenile seedlings. The results demonstrate the culture of P. urceolata from tetraspores under laboratory conditions.     

吉富罗非鱼最适生长水温研究

为研究不同养殖水温对吉富罗非鱼摄食和生长的影响,了解吉富罗非鱼的最适生长水温,实验设计28℃、30℃、32℃、34℃4个不同温度梯度,周期45 d。结果表明:不同水温环境下吉富罗非鱼表现出不同的生长特性,养殖在30℃水体中的罗非鱼生长速度明显高于其他温度组;水温对吉富罗非鱼的特定生长率、绝对增重率、饲料转化率、摄食率有显著影响(P<0.05),之间的相关关系可以用二次回归曲线来描述,特定生长率(SGR)与水温的关系式为rSGR=-19.255+1.3794T-0.0235T2,摄食率(FR)与水温的关系式为rFR=-22.175+1.5901T-0.026 6 T2,饲料转化率(FCR)与水温的关系式为rFCR=34.041-2.2256T+0.0382 T2;吉富罗非鱼的最适生长水温为29.3℃,最大摄食率的水温为29.9℃,最高食物转化率水温为29.1℃。     

Diurnal and seasonal dynamics of soil respiration at temperate Leymus chinensis meadow steppes in western Songnen Plain,China

To evaluate the diurnal and seasonal variations in soil respiration(Rs) and understand the controlling factors, we measured carbon dioxide(CO2) fluxes and their environmental variables using a LI-6400 soil CO2 flux system at a temperate Leymus chinensis meadow steppe in the western Songnen Plain of China in the growing season(May–October) in 2011 and 2012. The diurnal patterns of soil respiration could be expressed as single peak curves, reaching to the maximum at 11:00–15:00 and falling to the minimum at 21:00–23:00(or before dawn). The time-window between 7:00 and 9:00 could be used as the optimal measuring time to represent the daily mean soil CO2 efflux. In the growing season, the daily value of soil CO2 efflux was moderate in late spring(1.06–2.51 μmol/(m2·s) in May), increased sharply and presented a peak in summer(2.95–3.94 μmol/(m2·s) in July), and then decreased in autumn(0.74–0.97 μmol/(m2·s) in October). Soil temperature(Ts) exerted dominant control on the diurnal and seasonal variations of soil respiration. The temperature sensitivity of soil respiration(Q10) exhibited a large seasonal variation, ranging from 1.35 to 3.32, and decreased with an increasing soil temperature. Rs gradually increased with increasing soil water content(Ws) and tended to decrease when Ws exceeded the optimum water content(27%) of Rs. The Ts and Ws had a confounding effect on Rs, and the two-variable equations could account for 72% of the variation in soil respiration(p 0.01).     

Variations in soil temperature at BJ site on the central Tibetan Plateau

The temporal and spatial variation in soil temperature play a significant role in energy and water cycle between land surface and atmosphere on the Tibetan Plateau.Based on the observed soil temperature data(hourly data from 1 January 2001 to 31 December 2005)obtained by GAME-Tibet,the diurnal,seasonal and interannual variations in soil temperature at BJ site(31.37°N,91.90°E;4509 m a.s.l.)near Naqu in the central Tibetan Plateau were analyzed.Results showed that the average diurnal variation in soil temperature at 4 and 20 cm depth can be described as sinusoidal curve,which is consistent with the variation of solar radiation. However,the average diurnal variation in soil temperature under 60 cm was very weak.The average diurnal amplitude in soil temperature decreased by the exponential decay function with the increase of soil depth(R2=0.92,p<0.01).It is demonstrated that the average diurnal maximum soil temperature decreased by the exponential decay function with the increase of soil depth(R2=0.78,p<0.01).In contrast, the average diurnal minimum soil temperature increased by the exponential grow function with increasing of soil depth(R2=0.86,p<0.01).There were a linear negative correlation between the average annual maximum Ts and soil depth(R2=0.96, p<0.01),a logarithmic function relationship between the average annual minimum soil temperature and soil depth(R2=0.92,p<0.01).The average seasonal amplitude in soil temperature followed the exponential decay function with the increase of soil depth(R2=0.98,p<0.01).The mean annual soil temperature in each layer indicated a warming trend prominently.During the study period,the mean annual soil temperature at 4,20,40,60,80,100,130, 160,200 and 250 cm depth increased by 0.034,0.041, 0.061,0.056,0.062,0.050,0.057,0.051,0.047 and 0.042°C/a,respectively.     

Diurnal and seasonal variation of glacier meltwater hydrochemistry in Qiyi glacierized catchment in Qilian Mountains,Northwest China: implication for chemical weathering

In glacierized catchments, glacier runoff typically shows a strong diurnal cycle in the ablation season (June-September). To elucidate the effect of these processes on the chemical weathering, fresh snowfall and water samples were collected and studied from the supraglacial river, proglacial river, and gauging site in Qiyi glacierized catchment Qilian Mountains, Northwestern China, in the summer of 2011. The pH and electronic conductivity (EC) were determined in the field, and the concentrations of major ions (Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl^-, SO₄^2-, NO₃^-) were measured. The results indicated that EC linearly increased with increasing distance from the glacial snout, and the concentrations of major ions increased with increasing water-rock interaction time. Along the flow path of the glacier runoff, Na⁺ and Cl^- are more concentrated than other ions in the supraglacial river while Mg²⁺ and SO₄^2- are more concentrated than other ions at the gauging site. The discharge, pH, EC, and the concentrations of major ions exhibited significant diurnal variation along the flow path. On the other hand, the amplitude of variation diminished from upstream to downstream along the flow path. The chemical weathering rate (Na⁺+K⁺+Mg²⁺+Ca²⁺) was determined to be 10.9 t/yr/km². Moreover, further research indicated that the sampling method influenced the assessment of chemical weathering rates. When the sample was collected randomly in one diurnal cycle of hydrography, the estimated ionic flux could deviate -47%~73% based on estimated hourly data. In contrast, if three samples were collected at peak, base flow and the discharge decreasing rate starts to slow down in one diurnal cycle of hydrography, respectively, the deviation would be less than 15%. The smaller the diurnal variation of discharge, the smaller deviation calculated.