Spring Diatom Blooming Phases in a Representative Eutrophic Bay of the Three-Gorges Reservoir, China

We investigated dynamics of the phytoplankton community and abiotic factors in Xiangxi Bay of the Three-Gorge Reservoir, China, by daily sampling, a specific site during a spring algal bloom (February 23-April 28, 2005). Among the 76 taxa observed, Asterionella formosa and Cyclotella spp. were the dominants, accounting for 47.2% and 29.9% of the total abundance, respectively. We determined the five distinct developing phases of the bloom by analyzing the dissimilarity of physicochemical parameters. Simultaneously, six phytoplankton community groups were distinguished by TWINSPAN classifications. The pattern for algal community succession was similar to that for the bloom phase shift, and the structural complexity of communities significantly decreased over time. Water temperature and silicate were the main factors that related to the development of the bloom and the shifts of the phytoplankton community.

Effects of temperature on the threshold of phosphorus for algal blooms

Algal blooms, worsening marine ecosystems and causing great economic loss, have been paid much attention to for a long time. Such environmental factors as light penetration, water temperature, and nutrient concentration are crucial in blooms processes. Among them, only nutrients can be controlled. Therefore, the threshold of nutrients for algal blooms is of great concern. To begin with, a dynamic eutrophication model has been constructed to simulate the algal growth and phosphorus cycling. The model encapsulates the essential biological processes of algal growth and decay, and phosphorus regeneration due to algal decay. The nutrient limitation is based upon commonly used Monod's kinetics. The effects of temperature and phosphorus limitation are particularly addressed. Then, we have endeavored to elucidate the threshold of phosphorus at different temperature for algal blooms. Based on the numerical simulation, the isoquant contours of change rate of alga as shown in the figure are obtained, which obviously demonstrate the threshold of nutrient at an arbitrary reasonable temperature. The larger the change rate is, the more rapidly the alga grows. If the phosphorus concentration at a given temperature remains larger than the threshold the algal biomass may increase monotonically, leading to the algal blooming. With the rising of temperature, the threshold is apparently reduced, which may explain why likely red tide disasters occur in a fine summer day. So, high temperature and sufficient phosphorus supply are the major factors which result in algal growth and blowout of red tide.

真菌诱导子对青蒿发根生长和青蒿素生物合成的影响及开花与青蒿素生物合成的相关性研究

本论文主要包括以下两部分内容： 一、真菌诱导子对青蒿发根生长和青蒿素生物合成的影响 用3种真菌诱导子[大丽花轮枝孢（Verticillium dahliae Kleb.）、葡枝根霉(Rhizopus stolonifer (Ehrenb. ex Fr.) Vuill)和束状刺盘孢(Colleto trichumdematium (Pers.) Grove)]分别处理青蒿(Ar temisia annuaL．)的发根，这3种真菌诱导子均能促进发根中青蒿素的合成，其中以大丽花轮枝孢的诱导效果最好;对细胞生长均没有明显影响。经大丽花轮枝孢处理的发根中青蒿素含量达1. 12 mg/gDW，比对照(0. 77 mg/g DW)提高45%。诱导子的作用效果与诱导子浓度、诱导子作用时间及发根的生长状态有关。对大丽花轮枝孢来说，诱导子作用的最适浓度为每毫升培养基含糖0.4 mg;发根在指数生长末期对诱导作用最敏感：在加入诱导子4d后收获发根，发根中的青蒿素含量最高。 二、早花基因FPF1、co对青蒿开花时间的影响及开花与青蒿素生物合成的相关性 1．将来源于拟南芥的早花基因Flowering Promoting Factorl (FPFl)插入到植物表达载体pBI121中，构建CaMV 35S启动子控制下含FPFl基因的植物表达载体pBI121FPF/，用含有pBI121FPF/质粒的根癌农杆菌(Agrobacterium tumefaciens)LBA4404感染青蒿(Artemisia annua L.)叶片并诱导丛生芽，经卡那霉素筛选，获得转基因抗性植株。PCR、 PCR-Southem blot及Southern blot检测表明，外源基因FPFI已整合到青蒿基因组中：RT-PCR及RT-PCR Southern blot分析表明，外源基因在转录水平上已有表达。在短日照条件下，FPF1转基因植株的开花时间较对照提前20天左右，但提早开花的转基因植株与未开花的对照其青蒿素含量无明显差异，即提早开花并不能使开花植株的青蒿素含量有所提高，开花与青蒿素合成之间可能没有直接的关系。 2．将拟南芥的早花基因CONSTANS (CO)置于CaMV 35S启动子之下，通过根癌农杆菌(Agrobacterium tumefaciens)LBA4404介导转入青蒿(Artemisia annuaL．)，使之在青蒿中表达，并得到了抗性植株。PCR、PCR-Southem blot及Southemblot检测表明，外源基因co已整合到青蒿基因组中;RT-PCR及RT-PCR Southemblot分析表明，外源基因在转录水平上已有表达。在短日照条件下，co转基因植株的开花时间较对照提前2周左右，但提早开花的转基因植株的青蒿素含量与未丌花的对照无明显差异，即植株开花前青蒿素含量的提高并不是由于开花本身引起的，再次证明，开花与青蒿素合成之间可能没有直接的关系。

中国轮藻新植物和新记录

本文报道了轮藻科1新种、2新变种及4个中国新记录:不等丽藻 Nitella inaequabilis sP.nov,分叉丽藻齿网变种N.furcata var.dentireticulata var.nov.;普生轮藻等苞变种 Chara vulgaris var.aequibracteata var.nov.;裂顶丽藻 Nitella partita Nordst.;过渡丽藻N.transilis T.F.Allen;布洛丽藻 N.blowiana J.Grove;娇小丽藻 N.pulchella T.

Kinetic study of the 2-methyl-3-methoxy-4-phenylbutanoic acid produced by oxidation of microcystin in aqueous solutions

Microcystins (MCs) are a family of related cyclic hepatotoxic heptapeptides, of which more than 70 types have been identified. The chemically unique nature of the C20 beta-amino acid, (2S, 3S, 8S, 9S)-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca4,6-dienoic acid (Adda), portion of the MCs has been exploited to develop a strategy to analyze the entirety. Oxidation of MCs causes the cleavage of MC Adda to form 2-methyl-3-methoxy-4-phenylbutanoic acid (MMPB). In the present study, we investigated the kinetics of MMPB produced by oxidation of the most-often-studied MC variant, MC-LR (L = leucine, R = arginine), with permanganate-periodate. This investigation allowed insight regarding the influence of the reaction conditions (concentration of the reactants, temperature, and pH) on the conversion rate. The results indicated that the reaction was second order overall and first order with respect to both permanganate and MC-LR. The second-order rate constant ranged from 0.66 to 1.35 M/s at temperatures from 10 to 30 degrees C, and the activation energy was 24.44 kJ/mol. The rates of MMPB production can be accelerated through increasing reaction temperature and oxidant concentration, and sufficient periodate is necessary for the formation of MMPB. The initial reaction rate under alkaline and neutral conditions is higher than that under acidic conditions, but the former decreases faster than the latter except under weakly acidic conditions. These results provided new insight concerning selection of the permanganate-periodate concentration, pH, and temperature needed for the oxidation of MCs with a high and stable yield of MMPB.

Field studies on the environmental factors in controlling microcystin production in the subtropical shallow lakes of the Yangtze River

Microcystin (MC) problem made more and more care about in China, intercellular MC (Int-MC) and cellular MC (Cel-MC) were important contents to reflect the producing-MC ability by cyanobacteria and by lakes. To study the correlations between Int-MC, Cel-MC concentration and biological and environmental factors, eight cyanobacterial blooming lakes were studied in the middle and lower reaches of the Yangtze River. Microcystin-RR (MC-RR) and Microcystin-LR (MC-LR) were the primary toxin variants in our data. From the linear correlations between MC and environmental factors, cellular-YR had significant correlation with most of chemical factors except total nitrogen (TN) and the ratio of total nitrogen and total phosphorus (TN/TP), most intracellular MC analogues had significant correlations with total dissolved nitrogen (TDN), ammonium (NH4+), nitrite (NO2-), TP, total dissolved phosphorus (TDP), Microcystis. From the canonal correspondence analysis, Int-MC concentrations were closely related with the chemical and biological factors, such as TP, total organic carbon (TOC), chlorophyll a (Chl a), Microcystis biomass, et al. While Cel-MC contents, especially Cel-RR and Cel-LR, were closely related with light environmental in the lakes such as water depth and transparence.

Growth of Potamageton maackianus under low-light stress in eutrophic water

Decline of submersed macrophytes in Lake Donghu of China with the progress of eutrophication is assumedly due to low light stress by algae blooming. I conducted a laboratory experiment to study the impact of low-light stress on the growth of Potamogeton maackianus A. Been, a dominant submersed macrophyte of the lake before the 1970s. Plants were grown for six weeks in aquaria with Lake Donghu sediment and enriched water. Light delivered to aquaria was adjusted to simulate the typical Lake Donghu light intensities that exist at several water depths from 0.6m to 1.7m. Biomass growth of the plant was inversely related to light intensity at the simulated depths of greater than or equal to 1.0m (r = 0.96, p < 0.05, n=6) and was negative at the depths of greater than or equal to 1.4m. These results indicate that photosynthetic light saturation and compensation points of the plant in Lake Donghu should be ca. 0,9m and ca. 1.5m depths, respectively. Chlorophyll content, growth of main shoot, total shoot lengths and density of the plant all peaked at 1.2-1.3m simulated depths. These results indicate that P. maackianus responds to low light stress primarily by elongation of shoots, and increase of density. Its biomass growth and nutrient uptake rate did not correlate with the accelerated shoot growth. Below the light intensities of water deeper than 1.2-1.3m, shoot growth rate decreased. The flexible tolerant strategy of P. maackianus to low-light stress suggests that the disappearance of this plant from the lake was not mainly due to eutrophication-induced low-light stress.

Changes in the structure of a zooplankton community during a Ceratium (dinoflagellate) bloom in a eutrophic fishless pond

The community structure of zooplankton was studied in a eutrophic, fishless Japanese pond. The ecosystem was dominated by a dinoflagellate, Ceratium hirundinella, two filter-feeding cladocerans, Daphnia rosea and Ceriodaphnia reticulata, and an invertebrate predator, the dipteran Chaoborus flavicans. The midsummer zooplankton community showed a large change in species composition (the Daphnia population crashed) when a heavy Ceratium bloom occurred. It is shown that (i) the rapid density decline of D.rosea in mid-May was mainly caused by a shortage of edible phytoplankton, which was facilitated by the rapid increase in C.hirundinella abundance; (ii) the low density of D.rosea in June-July was considered to be mainly caused by the blooming of Ceratium hirundinella (which may inhibit the feeding process of D.rosea), while predation by C.flavicans larvae, the changing temperature, the interspecific competition and the scarcity of edible algae were not judged to be important; (iii) the high summer biomass of the planktonic C.flavicans larvae was maintained by the bloom of C.hirundinella, because >90% of the crop contents of C.flavicans larvae were C.hirundinella during this period. The present study indicates that the large-sized cells or colonies of phytoplankton are not only inedible by most cladocerans, but the selective effect of the blooming of these algae can also influence the composition and dominance of the zooplankton community, especially for the filter-feeding Cladocera, in a similar way as the selective predation by planktivorous fish. The large-sized phytoplankton can also be an important alternative food for ominivorous invertebrate predators such as Chaoborus larvae, and thus may affect the interactions between these predators and their zooplanktonic prey. In this way, such phytoplankton may play a very important role in regulating the dynamics of the aquatic food web, and become a driving force in shaping the community structure of zooplankton.

A colorimetric assay for screening microcystin class compounds in aquatic systems

Secondary metabolites produced by water-blooming cyanobacteria in eutrophic waters include some potent hepatotoxins, These compounds also have tumour-promoting properties, attributable to their inhibition and activation of protein phosphatases and kinases respectively. The inhibitory effect of these toxins on protein phosphatases have been employed in a commonly used radiometric assay, involving the use of a P-32-labeled substrate, for the detection and quantitation of these compounds. This paper investigates and describes a colorimetric method in which the activity of protein phosphatase 2A is determined by measuring the rate of colour production from the release of yellow p-nitrophenol using p-nitrophenyl phosphate as the substrate. Results of this study suggest that the colorimetric protein phosphatase inhibition assay is a simple, inexpensive tool for screening substances that may have tumour-promoting characteristics in aquatic systems. The detection limit of the colorimetric method is comparable to the radiometric assay. (C) 1998 Elsevier Science Ltd. All rights reserved.

长白山红松针阔混交林CO_2通量的日变化与季节变化

Diurnal and seasonal variation of CO_2 flux above the Korean Pine and broad_leaved mixed forest in Changbai Mountain were expounded according to the measurements by eddy covariance technique. The results showed that the diurnal variation during growing season was closely correlated with photosynthetically active radiation (PAR). The forest assimilated the CO_2 in daytime and released in night. The maximum uptake occurred about 9 o'clock of local time in clear day. Assimilation was synchronous to PAR in cloudy day. The night respiration increased with increasing of shallow soil temperature. The CO_2 flux also had obviously seasonal variation that was mainly controlled by temperature. Relationship between monthly net exchange of CO_2 and monthly mean air temperature fit cubic equation. Remarkable uptake occurred in blooming growing season,May to August,and weak respiration occurred in dormant season,October to March,and relatively big release happed in October. Assimilation and respiration were nearly balanced during the transition of growing and dormant seasons. The annual carbon uptake of the ecosystem was-184 gC·m -2 .

The dominant Ulva strain of the 2008 green algal bloom in the Yellow Sea was not detected in the coastal waters of Qingdao in the following winter

The region of Qingdao, China, experienced the world's largest green tide from May to July 2008. More than one million tons of fresh algal biomass of the green alga Ulva prolifera was harvested, while more was suspected to have sunk to the bottom. The original source of this seaweed was suspected to be from the south as revealed by satellite images. The floating biomass drifted with the water current northward and flourished in nearshore waters around Qingdao. However, direct biological evidence for "seed" source is lacking. It is still unclear whether this alga could survive the Qingdao local coastal environment and pose future danger of potential blooming. Systematic and seasonal sampling of waters in the intertidal zone at six collection sites along the Qingdao coast was conducted from December 2008 to April 2009. Forty-eight water samples were analyzed. From these, nine different morphotypes of Ulva were grown in the laboratory under standard temperature and light regimes. Growth of Ulva was observed in all water samples. However, molecular phylogenetic analyses revealed that the dominant U. prolifera strain of the 2008 bloom was absent in all the water-derived cultures during the sampling period. These results provide evidence that the dominant bloom-forming alga was unlikely able to survive the coastal waters (the minimal surface water temperature in February is 2A degrees C) in winter conditions in Qingdao, even though all the sampling locations were heavily covered by this alga in June 2008.

Effects of diatoms on reproduction and growth of marine copepods

Two hot spots in marine ecology, deleterious effects of diatoms and feeding selectivity of copepods, as well as new progress on these two issues achieved in the recent ten years, are reviewed. These two issues are considered correlated closely. Diatoms and their metabolites can induce deleterious effects on growth, reproduction and development of copepods, including increase of mortality and decrease of egg production, hatching and growth rates. Such negative effects, resulting from either chemical toxin or nutritional deficiency, can be conquered in natural environments by diverse feeding. It is therefore concluded that deleterious effects of diatoms observed in laboratory or during blooming period are only a special case that accommodation of feeding strategy of copepods is disabled. To understand their feeding strategy in natural environments is a prerequisite to explaining the mechanisms of deleterious effects caused by diatoms, and makes it possible to re-evaluate the energy flow in marine ecosystems.

东南极格罗夫山地区的土壤特征及其环境研究

The Grove Mountains, including 64 nunataks, is situated on an area about 3200km2 in the inland ice cap of east Antarctica in Princess Elizabeth land (72o20'-73°101S, 73°50'-75o40'E), between Zhongshan station and Dome A, about 450km away from Zhongshan station (69°22'S, 76°22'E). Many workers thought there was no pedogenesis in the areas because of the less precipitation and extreme lower temperature. However, during the austral summer in 1999-2000, the Chinaer 16 Antarctic expedition teams entered the inland East Antarctica and found three soil spots in the Southern Mount Harding, Grove Mountains, East Antarctica. It is the first case that soils are discovered in the inland in East Antarctica. Interestingly, the soils in this area show clay fraction migration, which is different from other cold desert soils. In addition, several moraine banks are discovered around the Mount Harding. The soil properties are discussed as below. Desert pavement commonly occurs on the three soil site surfaces, which is composed of pebbles and fragments formed slowly in typical desert zone. Many pebbles are subround and variegated. These pebbles are formed by abrasion caused by not only wind and wind selective transportation, but also salt weathering and thaw-freezing action on rocks. The wind blows the boulders and bedrocks with snow grains and small sands. This results in rock disintegration, paved on the soil surface, forming desert pavement, which protects the underground soil from wind-blow. The desert pavement is the typical feature in ice free zone in Antarctica. There developed desert varnish and ventifacts in this area. Rubification is a dominant process in cold desert Antarctic soils. In cold desert soils, rubification results in relatively high concentrations of Fed in soil profile. Stained depth increases progressively with time. The content of Fed is increasing up to surface in each profile. The reddish thin film is observed around the margin of mafic minerals such as biotite, hornblende, and magnetite in parent materials with the microscope analyzing on some soil profiles. So the Fed originates from the weathering of mafic minerals in soils. Accumulations of water-soluble salts, either as discrete horizons or dispersed within the soil, occur in the soil profiles, and the salt encrustations accumulate just beneath surface stones in this area. The results of X-ray diffraction analyses show that the crystalline salts consist of pentahydrite (MgSO4-5H2O), hexahydrite (MgSO4-6H2O), hurlbutite (CaBe2(PO4)2), bloedite (Na2Mg(S04)2-4H2O), et al., being mainly sulfate. The dominant cations in 1:5 soil-water extracts are Mg2+ and Na+, as well as Ca2+ and K+, while the dominant anion is SO42-, then NO3-, Cl- and HCO3-. There are white and yellowish sponge materials covered the stone underside surface, of which the main compounds are quartz (SiO2, 40.75%), rozenite (FeSOKkO, 37.39%), guyanaite (Cr2O3-1.5H2O, 9.30%), and starkeyite (MgSO4-4H2O, 12.56%). 4) The distribution of the clay fraction is related to the maximum content of moisture and salts. Clay fraction migration occurs in the soils, which is different from that of other cold desert soils. X-ray diffraction analyses show that the main clay minerals are illite, smectite, then illite-smectite, little kaolinite and veirniculite. Mica was changed to illite, even to vermiculite by hydration. Illite formed in the initial stage of weathering. The appearance of smectite suggests that it enriched in magnesium, but no strong eluviation, which belongs to cold and arid acid environment. 5) Three soil sites have different moisture. The effect moisture is in the form of little ice in site 1. There is no ice in site 2, and ice-cement horizon is 12 cm below the soil surface in site 3. Salt horizon is 5-10 cm up to the surface in Site 1 and Site 2, while about 26cm in site 3. The differentiation of the active layer and the permafrost are not distinct because of arid climate. The depth of active layer is about 10 cm in this area. Soils and Environment: On the basis of the characteristics of surface rocks, soil colors, horizon differentiation, salt in soils and soil depth, the soils age of the Grove Mountains is 0.5-3.5Ma. No remnants of glaciations are found on the soil sites of Mount Harding, which suggests that the Antarctic glaciations have not reached the soil sites since at least 0.5Ma, and the ice cap was not much higher than present, even during the Last Glacial Maximum. The average altitude of the contact line of level of blue ice and outcrop is 2050m, and the altitude of soil area is 2160m. The relative height deviation is about 110m, so the soils have developed and preserved until today. The parental material of the soils originated from alluvial sedimentary of baserocks nearby. Sporepollen were extracted from the soils, arbor pollen grains are dominant by Pinus and Betula, as well as a small amount Quercus, Juglans, Tilia and Artemisia etc. Judging from the shape and colour, the sporepollen group is likely attributed to Neogene or Pliocene in age. This indicates that there had been a warm period during the Neogene in the Grove Mountains, East Antarctica.