Photosynthesis and primary production in Lake Kasumigaura (Japan) monitored monthly since 1981

This study reports the primary production of phytoplankton determined with a ¹³C tracer, and their related variables, in Lake Kasumigaura, a shallow, hyper-eutrophic lake, and the second largest lake in Japan. Measurements were conducted monthly from August 1981 to December 2013 at four stations within the lake. Monitoring was a component of the Lake Kasumigaura Long-term Environmental Monitoring program, conducted by the National Institute for Environmental Studies (NIES) since 1977. The program collects data on water quality, and plankton and benthic communities. Lake Kasumigaura is registered as a core site of the Japan Long-term Ecological Research Network (JaLTER), which is a member of the International Long-term Ecological Research Network (ILTER). This dataset includes daily primary production (Pzd gC m^?2 d^?1) and the six parameters required to calculate Pzd: maximum photosynthesis rate (P _max gC gC^?1 h^?1); light irradiance at the junction of the initial slope (α (gC gC^?1 h^?1) (μmol photon m^?2 s^?1)^?1) and P _max of the photosynthesis vs. irradiance (P vs. E) curve (E _k μmol photon m^?2 s^?1); attenuation coefficient of photosynthetically available radiation (PAR) (K _PAR m^?1); water depth at each sampling station (Z _b , m); dissolved inorganic carbon (DIC mgC L^?1) and particulate organic carbon concentrations (POC gC m^?3); and chlorophyll a amounts (Chl.a μg L^?1). Daily primary production was calculated by obtaining a P vs. E curve over a short-term incubation (approximately 1 h) in a water tank using in situ water temperature in the laboratory, based on the field conditions of the sampling date. The dataset has been used for ecological studies as well as for management studies on water quality and ecosystems. This dataset is unique among the available published papers concerning lakes or primary production in various ecosystems, collected over a long period of time and freely available.     

Overwintering of Microcystis aeruginosa Kutz. in a shallow lake

The standing crop and photosynthetic activity of Microcystisaeruginosa Kütz. in both the plankton and sediment wereinvestigated from November 1979 to May 1982 in Lake Kasumigaura,Japan. The number of planktonic colonies of this species decreasedfrom early autumn to early spring, but increased in the sedimentduring late summer and autumn. The overwintering colonies inthe sediment were –100–1000 times greater per unitarea than those in lake water. No photoinhibition of photosynthesiscould be observed in overwintering Microcystis. The values ofthe initial slopes of photosynthesis-light (P-I) curves weresimilar to those of the summer population, although the maximumphotosynthetic rate (P_max) measured at 20°C was lower thanthat of the summer planktonic population. In winter the valuesof initial slope of the P-I curve, and the ratio of phycobilinto chlorophyll a sorted from sediment were higher than in coloniesfrom the plankton.     

Iron-stimulated toxin production in Microcystis aeruginosa.

Nitrate- and phosphate-limited conditions had no effect on toxin production by Microcystis aeruginosa. In contrast, iron-limited conditions influenced toxin production by M. aeruginosa, and iron uptake was light dependent. A model for production of toxin by M. aeruginosa is proposed.     

Interrelations between Microcystis and Cladocera in the highly Eutrophic Lake Kasumigaura,Japan

The zooplankton community in the highly eutrophic Lake Kasumigaura was investigated and its relation to a bloom of Microcystis was analyzed. The zooplankton community was dominated by small cladocerans, whose biomass and production became highest in summer, when Microcystis bloomed. The high cladoceran production is considered to depend on the production of colonial Microcystis, because the production of nannoplankton was apparently too low to ensure the cladoceran production. Microcystis cells were unsuitable as food for the cladocerans inhabiting Lake Kasumigaura, but became utilizable when decomposed. Decomposed Microcystis may be the main food for Cladocera in the lake in summer. High water temperatures occurring in summer probably promoted decomposition of the Microcystis, leading to increased production of the small cladocerans.     

Methods for prevention of mass development of the cyanobacterium Microcystis aeruginosa Kutz emend. Elenk. in aquatic systems

Methods for prevention of mass development of the cyanobacterium Microcystis aeruginosa Kutz emend. Elenk. in continental water bodies and industrial water supply systems are reviewed. The physicochemical, chemical, and biological methods for prevention of M. aeruginosa development in water bodies and water supply systems are considered; examples of successful inhibition of M. aeruginosa growth in laboratory experiments are demonstrated. The scientific problems are outlined that are to be solved for perfecting techniques for prevention of M. aeruginosa mass development in open water bodies and in closed water supply systems.     

Methods for prevention of mass development of the cyanobacterium Microcystis aeruginosa Kutz emend. Elenk. in aquatic ecosystems

Methods for prevention of mass development of the cyanobacterium Microcystis aeruginosa Kutz emend. Elenk. in continental water bodies and industrial water supply systems are reviewed. The physicochemical, chemical, and biological methods for prevention of M. aeruginosa development in water bodies and water supply systems are considered; examples of successful inhibition of M. aeruginosa growth in laboratory experiments are demonstrated. The scientific problems are outlined that are to be solved for perfecting techniques for prevention of M. aeruginosa mass development in open water bodies and in closed water supply systems.     

Natural occurrence of phycoerythrocyanin-like pigment in cyanobacterial blooming samples dominated by Microcystis in Lake Kasumigaura

We describe the occurrence of phycocyanin and phycoerythrocyanin-likepigment in natural Microcystis colonies collected in Lake Kasumigaura.For differentiating pigments, the combination of simultaneousdetermination of molecular weights of and ß and subunitsby electrospray ionization mass spectrometry with HPLC separationand fluorescence measurements was used. It was suggested thatthe natural Microcystis colonies may contain the phycoerythrocyanin-likepigment, judged from the excitation and emission spectra. Measuredpigments consisted of different molecular weights of and ßsubunits, but the molecular weights of and ß subunitsin both phycocyanin and phycoerythrocyanin-like pigments werenot always identical.     

HCO-3碱度增加对铜绿微囊藻光合活性和超微结构的影响

研究了不同重碳酸盐(HCO-3)碱度2.3 mmol/L(ALK2.3)和12.4 mmol/L(ALK12.4)对铜绿微囊藻(Microcystis aeruginosa FACHB 905)生长、光合特性、丙二醛(MDA)含量和超微结构的影响.实验结果表明,与对照相比碱度增加对铜绿微囊藻生物量抑制率分别为7%(ALK2.3)和55%(ALK12.4).对光合色素Chl a含量的抑制率分别为22%(ALK2.3)和88%(ALK12.4).Chl a/PC与对照相比先升高后降低.ALK2.3前期显著抑制光合活性,其它时期没有明显影响.ALK12.4对铜绿微囊藻光合活性表现出抑制-促进-抑制的作用模式.碱度诱导MDA含量的增加,碱度越高MDA含量增加越显著.超微结构表明,碱度增加使胞内类囊体数目减少,脂质体增加.表明碱度增加抑制光合色素的合成,破坏光合机构,进而抑制藻的光合活性,增加膜脂过氧化程度,对细胞产生伤害.     

Population dynamics and production of cladoceran zooplankton in the highly eutrophic Lake Kasumigaura

The growth rate, birth rate, death rate and production of the cladocera of Lake Kasumigaura were studied. Standing crop of zooplankton seemed to be governed by predation rather than food. Maximum productivity of cladocerans was observed in late August and early September. There were differences in production between sampling stations. The highest production was recorded in the most eutrophic basin, where heavy water blooms of Microcystis aeruginosa occurred. Maximum secondary production coincided with maximum primary production, which was mainly due to M. aeruginosa. Cladocerans probably utilize decomposed or decomposing Microcystis cells and bacteria in summer. Estimates of annual production of cladocerans varied from 4.2 to 13.1 g dry wt · m^–3, and annual P:B ratios ranged from 36 to 108. The production of cladocerans in Takahamairi Bay was 2.7% of gross primary production.     

Microcystin production by Microcystis aeruginosa in a phosphorus-limited chemostat

The production of microcystins (MC) from Microcystis aeruginosa UTEX 2388 was investigated in a P-limited continuous culture. MC (MC-LR, MC-RR, and MC-YR) from lyophilized M. aeruginosa were extracted with 5% acetic acid, purified by a Sep-Pak C(18) cartridge, and then analyzed by high-performance liquid chromatography with a UV detector and Nucleosil C(18) reverse-phase column. The specific growth rate (mu) of M. aeruginosa was within the range of 0.1 to 0.8/day and was a function of the cellular P content under a P limitation. The N/P atomic ratio of steady-state cells in a P-limited medium varied from 24 to 15 with an increasing mu. The MC-LR and MC-RR contents on a dry weight basis were highest at mu of 0.1/day at 339 and 774 microg g(-1), respectively, while MC-YR was not detected. The MC content of M. aeruginosa was higher at a lower mu, whereas the MC-producing rate was linearly proportional to mu. The C fixation rate at an ambient irradiance (160 microeinsteins m(-2) s(-1)) increased with mu. The ratios of the MC-producing rate to the C fixation rate were higher at a lower mu. Accordingly, the growth of M. aeruginosa was reduced under a P limitation due to a low C fixation rate, whereas the MC content was higher. Consequently, increases in the MC content per dry weight along with the production of the more toxic form, MC-LR, were observed under more P-limited conditions.     

Uptake of 13C and 15N (ammonium, nitrate and urea) by Microcystis in Lake Kasumigaura

The uptake rate of carbon and nitrogen (ammonium, nitrate andurea) by the Microcystis predominating among phytoplankton wasinvestigated in the summer of 1984 in Takahamaira Bay of LakeKasumigaura. The V_max values of Microcystis for nitrate (0.025–0.046h^–1) and ammonium (0.15–0.17 h^–1) were considerablyhigher than other natural phytoplankton. The ammonium, nitrateand urea uptake by Microcystis was light dependent and was notinhibited with nigh light intensity. The K₁ values were farlower than the I_k values. The carbon uptake was not influencedby nitrogen enrichment. Microcystis accelerated the uptake rateby changing V_max/K _s value when nitrogen versus carbon contentin cells declined. Nitrate was scarcely existent in TakahamairiBay during the summer, when Microcystis usually used ammoniumas the nitrogen source. However, the standing stock of ammoniumin the water was far lower than the daily ammonium uptake rates.Therefore, the ammonium in this water had to be supplied becauseof its rapid turn-over time (–0.7–2.6 h).     

松花湖铜绿微囊藻无菌株和单藻株生长因素的研究

用毛细滴管洗净法从松花湖分离纯化出铜绿微囊藻(Microcystisaeruginosa)的单藻株和无菌株,研究了温度、照度、N、P、Fe各种因素对单藻株和无菌株生长的影响。结果表明,各种因素对单藻株和无菌株最大比增长率的影响差别不大,单藻株和无菌株分别在温度33℃,照度5000Lx(2000Lx)、NO3-N浓度1.2mg·L-1,PO43-P浓度0.06mg·L-1,柠檬酸铁铁浓度0.05mg·L-1(0.04mg·L-1)时,达到最大比增长率。在一定浓度范围内,随着N、P、Fe浓度的增加,单藻株比无菌株的最大增长量高得多,可见附着细菌的存在,能促进铜绿微囊藻的生长。从松花湖湖水中N、P和Fe含量以及温度和照度的情况看,松花湖的某些区域已经基本具备了水华发生的条件。     

有机磷农药对滇池微囊藻生长和摄磷效应的影响

采集滇池水体作为铜绿微囊藻培养基,研究了两种有机磷农药(甲胺磷和辛硫磷)对微囊藻生长和摄磷效应的动力学规律。结果表明,在滇池水体中添加较低浓度的甲胺磷(0.8、1.6、3.2mg/L)和辛硫磷(0.02、0.06、0.1mg/L)均能不同程度地促进微囊藻的生长,且在HGZ培养基中抑制微囊藻生长的浓度在滇池水体中却能促进微囊藻的生长。微囊藻的生长取决于细胞内磷的浓度且对磷的吸收利用存在积累性,在微囊藻生长初期,摄取各形态磷的速率较快;随后微囊藻摄取各形态磷的速率较慢。总溶解磷(TSP)和溶解反应磷(SRP)是微囊藻优先摄取的磷形态,在生长过程中微囊藻利用了大量的溶解有机磷(DOP)作为磷源加速生长。这一特点对于微囊藻成为淡水湖泊富营养化发展过程中的一种重要优势种具有极为重要的作用。     

Origins of Replication in Sorangium cellulosum and Microcystis aeruginosa.

The genome of Sorangium cellulosum has recently been completely sequenced, and it is the largest bacterial genome sequenced so far. In their report, Schneiker et al. (in Complete genome sequence of the myxobacterium Sorangium cellulosum, Nat. Biotechnol., 2007, 25, 1281-1289) concluded that 'In the absence of the GC-skew inversion typically seen at the replication origin of bacterial chromosomes, it was not possible to discern the location of oriC'. In addition, the complete genome of Microcystis aeruginosa NIES-843 has also been recently sequenced, and in this report, Kaneko et al. (in Complete genomic structure of the bloom-forming toxic cyanobacterium Microcystis aeruginosa NIES-843, DNA Res., 2007, 14, 247-256) concluded that 'there was no characteristic pattern, according to GC skew analysis'. Therefore, oriC locations of the above genomes remain unsolved. Using Ori-Finder, a recently developed computer program, in both genomes, we have identified candidate oriC regions that have almost all sequence hallmarks of bacterial oriCs, such as asymmetrical nucleotide distributions, being adjacent to the dnaN gene, and containing DnaA boxes and repeat elements.     

铜绿微囊藻(Microcystis aeruginosa)对惠氏微囊藻(Microcystis wesenbergii)的化感作用

通过混合培养和添加过滤液两种方式观察铜绿微囊藻和惠氏微囊藻的生长曲线,探讨两种微囊藻之间的化感作用。结果表明:在混合培养条件下,两者能够形成相互抑制作用;当两者起始藻密度高于0.5×106cells.mL-1、混合比为1:1时,惠氏微囊藻的生长因化感作用而受到显著抑制(P<0.05),同时惠氏微囊藻也会对铜绿微囊藻产生一定的胁迫作用;处于对数生长期的铜绿微囊藻过滤液能抑制惠氏微囊藻的生长,且惠氏微囊藻起始藻密度低于0.5×106cells.mL-1,连续滴加该过滤液后,其生长受到极显著抑制(P<0.01)。     

Study of the dynamics of Microcystis aeruginosa and its cyanophage in East Lake using quantitative PCR

Dear Editor, East Lake,located in the middle and lower reaches of the Yangtze River,is a major source of drinking water for local residents.However,the large increase of population density and the rapid development of industry has resulted in heavy eutrophication of East Lake over the past few decades.Microcystis aeruginosa is a well-known toxic algae-blooming cyanobacterial species (Carmichael W W,et al.,2001) and a major player in the cyanobacterial water blooming in East Lake.     

Cryopreservation of a water-bloom forming cyanobacterium, Microcystis aeruginosa f. aeruginosa

A method for the Cryopreservation of Microcystis aeruginosa f. aeruginosa is described. For the five strains tested, dimethyl sulfoxide (DMSO) (3% v/v) was the only effective cryoprotectant for freezing to, and thawing from -196°C and allowed the successful recovery (>50%) of all the strains. The viability of frozen material was independent of the period of storage in liquid nitrogen. The strain NIES-44 (National Institute for Environmental Studies) had a recovery level of greater than 90% at 3–10% (v/v) DMSO in both two step and rapid cooling methods. The other three strains, NIES-87, 88 and 89 had greater than 60% of viability after freeze/thawing in presence of both 3% and 5% DMSO concentrations. On the other hand, the strain NIES-90 showed approximately 50% of viability in only 3% DMSO solution after two step cooling to and thawing from -196°C. This strain was damaged by greater than 4% DMSO and by rapid cooling to -196°C. It was found that cold shock injury and the cytotoxicity of DMSO were different at a strain level.     

Abundance and life history ofNeomysis intermedia Czerniawsky in Lake Kasumigaura

Weekly observations ofNeomysis intermedia in Lake Kasumigaura showed two major peaks in abundance during spring and autumn (more than 10⁴ individuals m^–2) and minimum levels in summer and winter (less than 10³ individuals m^–2). Their increase in abundance followed a high egg ratio, suggesting that the increase in abundance was caused by a high reproductive rate. Major contributors to mysid population decreases include fish predation and commercial fisheries, and possible horizontal migration of the mysids. N. intermedia showed two types of life history in the lake. One type (overwintering generation) has a life span of about 6–7 months and produces about 27 eggs per brood. Another, appearing from spring to autumn, matures in 3–6 weeks at a smaller size, and produces 12 eggs per brood. The reproductive season ofN. intermedia was continuous from March through November.