Mutual effects of nitric oxide and iron on the growth of marine algae

Experiments on the effects of nitric oxide （NO） and iron on the growth of marine microalgae Skeletonema costatum were conducted. The results are as follows： exogenous NO could increase the growth rate of marine algae and raise the biomass remarkably under iron-deficient conditions. But it was a complicated process that the phytoplankton growth was influenced by NO and iron, which was controlled by the NO concentration, the nutrition level of the culture medium and the iron concentration, etc. Meanwhile, the iron concentration in the medium also has a direct influence on the growth and NO release capacity of the algae. Therefore, the effects of NO and iron on the growth of marine phytoplankton were mutual.     

Research on Measurable Nonlinear Relationship Between Phytoplankton Biomass and Environmental Factors in Bohai Bay

Based on the data of phytoplankton and environmental factors in the Bohai Bay, the dependence between the concentration of phytoplankton and environmental factors is analysed by linear correlation coefficient, rank correlation coefficient and Hoeffding test of independence .The result shows that wind-speed, air-pressure, surface temperature, field pH, salinity, DO, silicate and NO 3 have a great impact on the concentration of phytoplankton.     

不同水动力下陆相碳酸钙沉积的蓝藻钙化试验的初步研究

 地表钙华,是喀斯特地区普遍存在的一种沉积体,是陆相碳酸钙沉积的重要类型。长期以来陆相碳酸钙沉积的水动力成因观点为大多数人所熟悉(1)（2）,生物成因观点则研究较少,在实际中生物作用过程也是不可忽略的,特别是藻类的沉积作用。论文以几种典型的蓝藻为例,通过对自然界水动力条件的模拟,对蓝藻藻类进行了几种水动力条件下的碳酸钙生物沉积试验研究,对比研究了在不同水动力条件下,蓝藻钙化沉积过程。试验得出了钙藻生长与钙化沉积的最适宜水动力为0~60 rpm,在过强的水动力条件下,蓝藻的生长将受到抑制,从而降低蓝藻的钙化沉积速率。文章讨论了在瀑布条件下的陆相碳酸钙沉积是以水动力成因为主导,而在水动力条件较弱的河流中以生物成因为主导,从而提出了,陆相碳酸钙沉积的水动力-生物双成因观点。文章还探讨了在静止状态下,藻类沉积对碳酸钙沉积的贡献大小,叠层石所指示的安静的沉积环境。      

Depth profiles of volatile iodine and bromine-containing halocarbons in coastal Antarctic waters

Measurements of bromoform (CHBr₃), diiodomethane (CH₂I₂), chloroiodomethane (CH₂ICl) and bromoiodomethane (CH₂IBr) were made in the water column (5–100 m depth) of the Southern Ocean within 0–40 km of the Antarctic sea ice during the ANTXX1/2 transect of the German R/V Polarstern, at five locations between 70–72°S and 9–11°W in the Antarctic spring/summer of 2003–2004. Some of the profiles exhibited a very pronounced layer of surface sea-ice meltwater, as evidenced by salinity minima and temperature maxima, along with surface maxima in concentrations of CHBr₃, CH₂I₂, CH₂ICl and CH₂IBr. These results are consistent with in situ surface halocarbon production by ice algae liberated from the sea ice, although production within the sea ice followed by transport cannot be entirely ruled out. Additional sub-surface maxima in halocarbons occurred between 20 and 80 m. At a station further from shore and not affected by surface sea-ice meltwater, surface concentrations of CH₂I₂ were decreased whereas CH₂ICl concentrations were increased compared to the stations influenced by meltwater, consistent with photochemical conversion of CH₂I₂ to CH₂ICl, perhaps during upward mixing from a layer at  70 m enhanced in iodocarbons. Mean surface (5–10 m) water concentrations of halocarbons in these coastal Antarctic waters were 57 pmol l^− 1 CHBr₃ (range 44–78 pmol l^− 1), 4.2 pmol l^− 1 CH₂I₂ (range 1.7–8.2 pmol l^− 1), 0.8 pmol l^− 1 CH₂IBr (range 0.2–1.4 pmol l^− 1), and 0.7 pmol l^− 1 CH₂ICl (range 0.2–2.4 pmol l^− 1). Concurrent measurements in air suggested a sea-air flux of bromoform near the Antarctic coast of between 1 and 100 (mean 32.3, median 10.4) nmol m^− 2 day^− 1 and saturation anomalies of 557–1082% (mean 783%, median 733%), similar in magnitude to global shelf values. In surface samples affected by meltwater, CH₂I₂ fluxes ranged from 0.02 to 6.1 nmol m^− 2 day^− 1, with mean and median values of 1.9 and 1.1 nmol m^− 2 day^− 1, respectively.     

旅游活动对黄龙景区磷酸盐浓度和水藻生长的影响

由于其独特的钙华景观,黄龙风景区从1992年被联合国教科文组织列入世界自然遗产名录以来,每年吸引数以十万甚至百万计的国内外游客前来游览;然而,可能由于旅游活动的影响,近年来黄龙钙华景观出现了诸多形式的退化,水藻加速生长钙华黑化即是其表现形式之一。为了阐明这一退化现象是否与旅游活动有关,从2010年5月底到11月初的丰水时段,采用野外自动监测和室内分析相结合的方法,对溪流水藻叶绿素含量和水中的磷酸盐浓度变化进行了研究。结果发现,随着景区游客人数的增减,水中磷酸盐浓度呈现出与之一致的变动趋势;同时,叶绿素与磷酸盐间也呈现出明显一致的变动趋势。因此,我们认为,旅游活动增加了黄龙景区的磷酸盐浓度,并促进了水藻的生长,这很可能是黄龙水藻近年来加速生长的重要原因,值得引起有关方面的高度关注。     

Trophic ecology of the sea urchin Spatangus purpureus elucidated from gonad fatty acids composition analysis

Irregular sea urchins such as the spatangoid Spatangus purpureus are important bioturbators that contribute to natural biogenic disturbance and the functioning of biogeochemical cycles in soft sediments. In the coastal waters of the Balearic Islands S. purpureus occurs in soft red algal beds, and can reach high densities. The diet of S. purpureus is unknown and it is particularly difficult to analyze the stomach contents of this group; therefore, we analyzed the fatty acid (FA) composition of the gonads and potential food resources in order to assess the trophic relationships of this species. The FA profiles of the gonads of S. purpureus agree well with the FA composition of the potential trophic resources (algae and sediment) and reveals changes between localities with different available resources. Three polyunsaturated FAs mainly contributes in the composition in the S. purpureus gonads: eicosapentaenoic acid (C20:5n-3) and arachidonic acid (C20:4n-6), both abundant in the macroalgal material, and palmitoleic acid (C16:1n-7), which is characteristic of sediment samples. Trophic markers of bacterial input and carnivorous feeding were significantly more abundant in sea urchins caught on bottoms with less vegetation. The current study demonstrates that the FA content of S. purpureus gonads is a useful marker of diet, as differences in the profiles reflected the variations in detritus composition. The results of this study show that this species has omnivorous feeding behavior; however, viewed in conjunction with available abundance data the results suggest that phytodetritus found within algal beds is an important carbon source for this species.     

古尔班通古特沙漠南缘典型沙垄藻类的时空分布

 通过研究春、夏 、秋3季古尔班通古特沙漠典型沙垄藻类物种多样性、种类组成和生物量的变化,分析了典型沙垄中藻类的时空分布特征。结果表明:①地貌部位和不同土层对物种多样性指数影响极显著(P<0.01); 在垂直层次中,藻类物种多样性指数由表及里逐渐降低。②在不同地貌部位和季节中,藻类的种类组成亦表现出一定的差异。垄间低地和背风坡球形藻类和丝状藻类丰富,迎风坡以丝状藻类占优势,垄顶藻类的种类和数量都有明显的下降。③地貌部位、垂直层次和季节对藻类生物量的影响均极显著(P<0.01)。藻类在沙漠典型沙垄的分布具有空间异质性,将影响到生物结皮的发育,使其处于不同的发育阶段,而它们在生物结皮中的地位和作用亦不同。     

The study on the effect of NO on the growth of Chaetoceros curvisetus

1 INTRODUCTION As a recently recognized information molecule in campaign of the “Molecule of the Year” by Sci- ence magazine, nitric oxide (NO) has attracted much attention from biologists and many other field scien- tists, for its very important physio…