Impacts of two biomanipulation fishes stocked in a large pen on the plankton abundance and water quality during a period of phytoplankton seasonal succession

Silver and bighead carp were stocked in a large pen to control the nuisance cyanobacterial blooms in Meiliang Bay of Lake Taihu. Plankton abundance and water quality were investigated about once a week from 9 May to 7 July in 2005. Biomass of both total crustacean zooplankton and cladocerans was significantly suppressed by the predation of pen-cultured fishes. There was a significant negative correlation between the N:P weight ratio and phytoplankton biomass. The size-selective predation by the two carps had no effect on the biomass of green alga Ulothrix sp. It may be attributed to the low fish stocking density (less than 40 g m(-3)) before June. When Microcystis dominated in the water of fish pen, the pen-cultured carps effectively suppressed the biomass of Microcystis, as indicated by the significant decline of chlorophyll a in the >38 mu m fractions of the fish pen. Based on the results of our experiment and previous other studies, we conclude that silver and bighead carp are two efficient biomanipulation tools to control cyanobacterial (Microcystis) blooms in the tropical/subtropical eutrophic waters. Moreover, we should maintain an enough stocking density for an effective control of phytoplankton biomass. (C) 2008 Elsevier B.V All rights reserved

A Review of Nontraditional Biomanipulation

The aim of this review is to identify problems, find general patterns, and extract recommendations for successful management using nontraditional biomanipulation to improve water quality. There are many obstacles that prevent traditional biomanipulation from achieving expectations: expending largely to remove planktivorous fish, reduction of external and internal phosphorus, and macrophyte re-establishment. Grazing pressure from large zooplankton is decoupled in hypereutrophic waters where cyanobacterial blooms flourish. The original idea of biomanipulation (increased zooplankton grazing rate as a tool for controlling nuisance algae) is not the only means of controlling nuisance algae via biotic manipulations. Stocking phytoplanktivorous fish may be considered to be a nontraditional method; however, it can be an effective management tool to control nuisance algal blooms in tropical lakes that are highly productive and unmanageable to reduce nutrient concentrations to low levels. Although small enclosures increase spatial overlap between predators and prey, leading to overestimates of the impact of predation, microcosm and whole-lake experiments have revealed similar community responses to major factors that regulate lake communities, such as nutrients and planktivorous fish. Both enclosure experiments and large-scale observations revealed that the initial phytoplankton community composition greatly impacted the success of biomanipulation. Long-term observations in Lake Donghu and Lake Qiandaohu have documented that silver carp (Hypophthalmichthys molitrix) and bighead carp (H. nobilis) (two filter-feeding planktivorous species commonly used in management) can suppress Microcystis blooms efficiently. The introduction of silver and bighead carp could be an effective management technique in eutrophic systems that lack macrozooplankton. We confirmed that nontraditional biomanipulation is only appropriate if the primary aim is to reduce nuisance blooms of large algal species, which cannot be controlled effectively by large herbivorous zooplankton. Alternatively, this type of biomanipulation did not work efficiently in less eutrophic systems where nanophytoplankton dominated.

溶藻菌群对铜绿微囊藻的溶藻效应及其作用机理研究

水华暴发是一个世界性的问题，近年来在发展中国家显得尤其严重。水华暴发给环境和公众健康带来巨大灾难，一些蓝藻产生的毒素可以造成鱼类、鸟禽和家畜的死亡，而臭名昭著的微囊藻产生的微囊藻毒素更是有强烈致癌效应。因此，寻找控制水华藻类的有效方法非常迫切。在利用物理和化学方法处理不甚理想的情况下，利用溶藻细菌控藻成为一个新的研究方向。溶藻细菌一般直接从富营养化水体中分离，杀藻活力对有害蓝藻具有较强的选择性而不危害其它生物，尤其适合在水华发生初期使用，可以在短时间内达到阻止藻类增殖的效果。本研究富集分离到一个高效溶解铜绿微囊藻的溶藻菌群，对其溶藻效应和溶藻机制进行了探索研究。 1溶藻菌群的富集筛选及其溶微囊藻效果 富集筛选得到一个有明显抑藻效果的菌群，它对铜绿微囊藻有显著溶藻效果。与对照组相比，加入富集的溶藻菌后，第4 d开始出现溶藻现象，6~8 d出现明显的溶藻效果，8 d后测得叶绿素去除率在85%以上。 2 溶藻菌群的作用范围及溶藻特性 富集分离到的溶藻菌群对铜绿微囊藻和念珠藻有显著溶藻作用，对水华微囊藻和其它几株受试微囊藻没有明显溶藻效应。该溶藻菌群不仅可以在液体中溶解铜绿微囊藻，生长在固体平板上的藻苔也有一定的溶藻效应，生成溶藻空斑。保证快速溶藻的最大稀释度可以达到1/100, 000。 3 环境因子对菌群溶藻效力的影响 试验发现，不同的pH、温度、和光照条件下，溶藻菌群溶藻效力明显不同，且不同种类的氮源对其溶藻作用也有一定影响。这些条件对该菌群溶藻作用的影响，在相当的程度上可能取决于它们对藻和细菌两者的生长状况的影响综合。 4 溶藻菌群的溶藻作用机理 溶藻菌液过滤除菌和煮沸灭菌处理后溶藻液，未见明显的溶藻效果，只有原液具有很好的溶藻效果。因此可初步确定，蓝藻细胞的溶解可能是由溶藻菌直接接触藻细胞产生的作用效果。显微镜观察发现，细菌在溶藻的过程中频繁地接触藻细胞并侵入藻细胞，破坏进而裂解杀死藻细胞。这也进一步说明了此溶藻菌是通过直接方式杀藻。 5 溶藻菌群的菌群结构解析 分离有溶藻效果的纯菌的多次尝试都没有成功。结合DGGE和16S rDNA文库综合分析发现：Rubritepida菌，假单胞菌和鞘氨醇单胞菌是存在于铜绿微囊藻中的三种伴生细菌。加入富集的溶藻菌群后，菌群结构发生明显的变化，Rubritepida菌、假单胞菌消失，混合菌群则包含未培养黄杆菌，鞘氨醇单胞菌和噬氢菌，其中黄杆菌是优势菌群，并且细菌种群结构的变化与藻细胞消亡之间有显著的相关性。通过菌种的分离鉴定与DGGE和16S rDNA文库的测序结果比较，一些未培养菌可能在溶藻过程中起重要调控作用。 6 溶藻细菌控藻应用基础 (1) 扩大规模的模拟水华实验进一步确定了细菌对微囊藻的强烈溶解作用。 (2) 铜绿微囊藻(Microcystis aeruginosa 905, zc)、微囊藻(Microcystis spp., zd)和溶藻菌群共培养试验表明，zc可以抑制zd生长，而溶藻菌群可以溶zc。 本研究是第一次报道混合菌群的溶藻效应。该溶藻菌群对带有藻际细菌的铜绿微囊藻具有高效的溶藻效力，表明它对自然界中存在的带菌铜绿微囊藻和其它一些蓝藻的生消具有一定的控制作用。对进一步研究菌藻关系与生态学作用，以及对富营养化湖泊和水库水体中蓝藻暴发的防控，该菌群具有一定的应用潜力。 Cyanobacterial blooms break out frequently all over the world, especially in developing countries. Blooms create enormous disasters to public health and to the environment. Some cyanobacterial blooms produce extremely toxic substances that have killed fish, domestic animals and birds. It has been well known that microcystins, a hepatoxin produced by Microcystis, can promote tumors in humans. So it is very important to find an effective method for controlling the growth of the bloom-forming algae. Measures for controlling such kind of algae include physical, chemic and biologic means, but the former two may damage the aquatic environment and require high-energy inputs. The alternative approach for the elimination of nuisance algae involves the application of algicidal bacteria. The algicidal bacteria, which are nontoxic to other organisms and most of which are isolated from the eutrophic lake in situ, may be potential microbial algaecides. In the initial stages of the water blooms, they are able to restrain the biomass or multiplication of the bloom-forming algae in a short time. In order to use algicidal bacteria to suppress blooms of M. aeruginosa, we isolated a bacterial culture capable of lysing the noxious cyanobacteria M. aeruginosa. In this paper we described some properties of the bacterial culture and its growth-inhibiting or algicidal effects on the growth of M. aeruginosa, and investigated its algicidal mechanisms. 1 Enrichment of a microbial culture that lyses Microcystis aeruginosa A mixed bacterial culture was isolated from a hypereutrophic pond and showed significant algicidal activity against the noxious Microcystis aeruginosa. Algae lysis would be seen obviously 4 days later when the algae culture was killed and became yellow contrast to no-addition controls, and chlorophyll a (chl-a) reduction went beyond 85% 8 days later. 2 The host range and some other algicidal feature of the mixed algicidal culture. Microcystis aeruginosa, Nostoc sp., were susceptible to the mixed algicidal culture, while the lytic effects of this mixed culture on Microcystis flos-aquae and some other tested Microcystis were feeble.The algicidal culture can not only lyse M. aeruginosa in liquid media, but aslo lyse M. aeruginosa lawns on soft agar plates and form plaques. The maximun dilution of the mixed culture required for rapid Microcystis lysis is 1/100, 000. 3 Influences of environmental factors such as pH, temperature, illumination, and the nitrogen source on the lytic activity of the mixed bacterial culture on Microcystis aeruginosa. In our investigations, it was shown that the lytic activity of the mixed bacterial culture on Microcystis aeruginosa was straightly correlated with pH, temperature, illumination, as well as the nitrogen source in the medium. The impacts of these environmental factors on the algicidal activity of the mixed bacterial culture, to a certain extent, may depend on both the algal and the bacterial growth rates under the tested environmental conditions. 4 The mechanisms of algal cell lysis by the algicidal bacteria Death was detected when the mixed bacterial culture was added to the algal culture, but not when only the culture filtrate or autoclaved bacterial culture was added. This indicates that the mixed bacterial culture did not release extracellular products inhibitory to Microcystis aeruginosa. In addition, under the microscope, we observed frequent contacts btween bacteria and algae cells, and some bacteria can even penetrate into target algal cells and destroyed them. These results may suggest that the bacterium kill the alga by direct contact. 5 Molecular Characterization of the algicidal bacterial culture Attempts for isolation of pure bacterium or bacteria from the enrichment culture responsible for Microcystis lysis have so far been failed. Based on PCR-DGGE (denaturing gradient gel electrophoresis) and 16S rDNA clone library analysis, Rubritepida sp., Pseudomonas sp. and Sphingomonas sp., as accompanying bacteria, were existed in M. aeruginosa. The bacterial community in M. aeruginosa showed significant change after adding the enrichment culture, where uncultured Flavorbacterium sp., Sphingomonas sp. and Hydrogenophaga sp. were observed, and the uncultured Flavorbacterium sp. became a dominant species. The obvious correlation can be seen between change of bacterial population and extinction of M. aeruginosa. Compared identification of pure bacterium with sequencing of DGGE bands and the clone distribution of the clone libraries, it was inferred that some uncultured bacteria were probably play an important role in controlling the growth and abundance of M. aeruginosa. This report is the first example of a mixed bacterial culture with the ability to lyse M. aeruginosa. 6 Further study for algae control by applications of algicidal bacteria (1) Algae lysis would be seen obviously 6 days later when the algae culture was killed and became yellow contrast to no-addition controls, and chlorophyll a (chl-a) was reducted to a low level 20 days later in the simulated water bloom experiments. (2) The growth of Microcystis sp. (zd) was restrained by Microcystis aeruginosa 905 (zc) when they were co-cultured together, and zc was lysed by the algicidal bacterial culture. This report is the first example of a mixed bacterial culture with the ability to lyse M. aeruginosa, and its algicidal activity remained high against non-axenic tested M. aeruginosa, suggesting that bacteria in the natural environment could play a role in controlling the growth and abundance of M. aeruginosa and other cyanobacteria. Such bacteria could also potentially be used as agents to prevent the mass development of cyanobacteria in eutrophic lakes and reservoirs.

Jackson v JH Watson Property Investment Ltd.

Comments on the Chancery Division decision in Jackson v JH Watson Property Investment Ltd on whether a landlord was liable in nuisance to a long leaseholder in respect of damage caused to the demised property by a building defect which pre-dated the grant of the lease or whether the principle of caveat lessee applied. Considers whether the defect amounted to "disrepair" within the meaning of the landlord's repairing covenant.

Case history and persistence of the non-indigenous diatom Coscinodiscus wailesii in the north-east Atlantic

The introduction of non-indigenous marine plankton species can have a considerable ecological and economic effect on regional systems. Their presence, however, can go unnoticed until they reach nuisance status and as a consequence few case histories exist containing information on their initial appearance and their spatio-temporal patterns. Here we report on the occurrence of the non-indigenous diatom Coscinodiscus wailesii in 1977 in the English Channel, its subsequent geographical spread into European shelf seas, and its persistence as a significant member of the diatom community in the north-east Atlantic from 1977-1995.

Identification of genetically and oceanographically distinct blooms of jellyfish

Reports of nuisance jellyfish blooms have increased worldwide during the last half-century, but the possible causes remain unclear.Apersistent difficulty lies in identifying whether blooms occur owing to local or regional processes. This issue can be resolved, in part, by establishing the geographical scales of connectivity among locations, which may be addressed using genetic analyses and oceanographic modelling. We used landscape genetics and Lagrangian modelling of oceanographic dispersal to explore patterns of connectivity in the scyphozoan jellyfish Rhizostoma octopus, which occurs en masse at locations in the Irish Sea and northeastern Atlantic. We found significant genetic structure distinguishing three populations, with both consistencies and inconsistencies with prevailing physical oceanographic patterns. Our analyses identify locations where blooms occur in apparently geographically isolated populations, locations where blooms may be the source or result of migrants, and a location where blooms do not occur consistently and jellyfish are mostly immigrant. Our interdisciplinary approach thus provides a means to ascertain the geographical origins of jellyfish in outbreaks, which may have wide utility as increased international efforts investigate jellyfish blooms. © 2013 The Authors.

Loss-of-Mains Detection by Internet Based ROCOF

This paper considers the enhancement of loss-of-mains detection by use of a differential rate-of-change-of-frequency relay to reduce nuisance tripping and improve sensitivity to small excursions in frequency. The telecommunications media which might carry the differential ROCOF signal are reviewed with a focus on channel latency, bandwidth and security.

Loss-of-Mains Protection System by Application of Phasor Measurement Unit Technology with Experimentally Assessed Threshold Settings

Loss-of-mains protection is an important component of the protection systems of embedded generation. The role of loss-of-mains is to disconnect the embedded generator from the utility grid in the event that connection to utility dispatched generation is lost. This is necessary for a number of reasons, including the safety of personnel during fault restoration and the protection of plant against out-of-synchronism reclosure to the mains supply. The incumbent methods of loss-of-mains protection were designed when the installed capacity of embedded generation was low, and known problems with nuisance tripping of the devices were considered acceptable because of the insignificant consequence to system operation. With the dramatic increase in the installed capacity of embedded generation over the last decade, the limitations of current islanding detection methods are no longer acceptable. This study describes a new method of loss-of-mains protection based on phasor measurement unit (PMU) technology, specifically using a low cost PMU device of the authors' design which has been developed for distribution network applications. The proposed method addresses the limitations of the incumbent methods, providing a solution that is free of nuisance tripping and has a zero non-detection zone. This system has been tested experimentally and is shown to be practical, feasible and effective. Threshold settings for the new method are recommended based on data acquired from both the Great Britain and Ireland power systems.

A novel radial basis function neural network principal component analysis scheme for PMU-based wide-area power system monitoring

A novel model-based principal component analysis (PCA) method is proposed in this paper for wide-area power system monitoring, aiming to tackle one of the critical drawbacks of the conventional PCA, i.e. the incapability to handle non-Gaussian distributed variables. It is a significant extension of the original PCA method which has already shown to outperform traditional methods like rate-of-change-of-frequency (ROCOF). The ROCOF method is quick for processing local information, but its threshold is difficult to determine and nuisance tripping may easily occur. The proposed model-based PCA method uses a radial basis function neural network (RBFNN) model to handle the nonlinearity in the data set to solve the no-Gaussian issue, before the PCA method is used for islanding detection. To build an effective RBFNN model, this paper first uses a fast input selection method to remove insignificant neural inputs. Next, a heuristic optimization technique namely Teaching-Learning-Based-Optimization (TLBO) is adopted to tune the nonlinear parameters in the RBF neurons to build the optimized model. The novel RBFNN based PCA monitoring scheme is then employed for wide-area monitoring using the residuals between the model outputs and the real PMU measurements. Experimental results confirm the efficiency and effectiveness of the proposed method in monitoring a suite of process variables with different distribution characteristics, showing that the proposed RBFNN PCA method is a reliable scheme as an effective extension to the linear PCA method.

Campanha de comunicação de Ambient Media para a marca Leroy Merlin

Trabalho de projeto apresentado à Escola Superior de Comunicação Social como parte dos requisitos para obtenção de grau de mestre em Publicidade e Marketing.

Letter health consultation : foundry slag used for road rock, Washington County, Iowa (2008)

A resident within one of the counties in your region has expressed some concern regarding potential adverse health effects from dust and material that may be found within foundry slag that has been used as a replacement for road rock. This consultation includes a comparison of nuisance issues from dust generated from a road constructed of foundry slag and dust generated from a road constructed from typical road rock. This consultation also includes a discussion of the potential health effects of exposure of heavy metals from incidental ingestion of foundry slag.

Simulation-Based Finite and Large Sample Tests in Multivariate Regressions.

In the context of multivariate linear regression (MLR) models, it is well known that commonly employed asymptotic test criteria are seriously biased towards overrejection. In this paper, we propose a general method for constructing exact tests of possibly nonlinear hypotheses on the coefficients of MLR systems. For the case of uniform linear hypotheses, we present exact distributional invariance results concerning several standard test criteria. These include Wilks' likelihood ratio (LR) criterion as well as trace and maximum root criteria. The normality assumption is not necessary for most of the results to hold. Implications for inference are two-fold. First, invariance to nuisance parameters entails that the technique of Monte Carlo tests can be applied on all these statistics to obtain exact tests of uniform linear hypotheses. Second, the invariance property of the latter statistic is exploited to derive general nuisance-parameter-free bounds on the distribution of the LR statistic for arbitrary hypotheses. Even though it may be difficult to compute these bounds analytically, they can easily be simulated, hence yielding exact bounds Monte Carlo tests. Illustrative simulation experiments show that the bounds are sufficiently tight to provide conclusive results with a high probability. Our findings illustrate the value of the bounds as a tool to be used in conjunction with more traditional simulation-based test methods (e.g., the parametric bootstrap) which may be applied when the bounds are not conclusive.

Exact Tests for Contemporaneous Correlation of Disturbances in Seemingly Unrelated Regressions.

This paper proposes finite-sample procedures for testing the SURE specification in multi-equation regression models, i.e. whether the disturbances in different equations are contemporaneously uncorrelated or not. We apply the technique of Monte Carlo (MC) tests [Dwass (1957), Barnard (1963)] to obtain exact tests based on standard LR and LM zero correlation tests. We also suggest a MC quasi-LR (QLR) test based on feasible generalized least squares (FGLS). We show that the latter statistics are pivotal under the null, which provides the justification for applying MC tests. Furthermore, we extend the exact independence test proposed by Harvey and Phillips (1982) to the multi-equation framework. Specifically, we introduce several induced tests based on a set of simultaneous Harvey/Phillips-type tests and suggest a simulation-based solution to the associated combination problem. The properties of the proposed tests are studied in a Monte Carlo experiment which shows that standard asymptotic tests exhibit important size distortions, while MC tests achieve complete size control and display good power. Moreover, MC-QLR tests performed best in terms of power, a result of interest from the point of view of simulation-based tests. The power of the MC induced tests improves appreciably in comparison to standard Bonferroni tests and, in certain cases, outperforms the likelihood-based MC tests. The tests are applied to data used by Fischer (1993) to analyze the macroeconomic determinants of growth.

Simulation-Based Finite-Sample Tests for Heteroskedasticity and ARCH Effects.

A wide range of tests for heteroskedasticity have been proposed in the econometric and statistics literature. Although a few exact homoskedasticity tests are available, the commonly employed procedures are quite generally based on asymptotic approximations which may not provide good size control in finite samples. There has been a number of recent studies that seek to improve the reliability of common heteroskedasticity tests using Edgeworth, Bartlett, jackknife and bootstrap methods. Yet the latter remain approximate. In this paper, we describe a solution to the problem of controlling the size of homoskedasticity tests in linear regression contexts. We study procedures based on the standard test statistics [e.g., the Goldfeld-Quandt, Glejser, Bartlett, Cochran, Hartley, Breusch-Pagan-Godfrey, White and Szroeter criteria] as well as tests for autoregressive conditional heteroskedasticity (ARCH-type models). We also suggest several extensions of the existing procedures (sup-type of combined test statistics) to allow for unknown breakpoints in the error variance. We exploit the technique of Monte Carlo tests to obtain provably exact p-values, for both the standard and the new tests suggested. We show that the MC test procedure conveniently solves the intractable null distribution problem, in particular those raised by the sup-type and combined test statistics as well as (when relevant) unidentified nuisance parameter problems under the null hypothesis. The method proposed works in exactly the same way with both Gaussian and non-Gaussian disturbance distributions [such as heavy-tailed or stable distributions]. The performance of the procedures is examined by simulation. The Monte Carlo experiments conducted focus on : (1) ARCH, GARCH, and ARCH-in-mean alternatives; (2) the case where the variance increases monotonically with : (i) one exogenous variable, and (ii) the mean of the dependent variable; (3) grouped heteroskedasticity; (4) breaks in variance at unknown points. We find that the proposed tests achieve perfect size control and have good power.

Testing Mean-Variance Efficiency in CAPM with Possibly Non-Gaussian Errors : An Exact Simulation-Based Approach

In this paper we propose exact likelihood-based mean-variance efficiency tests of the market portfolio in the context of Capital Asset Pricing Model (CAPM), allowing for a wide class of error distributions which include normality as a special case. These tests are developed in the frame-work of multivariate linear regressions (MLR). It is well known however that despite their simple statistical structure, standard asymptotically justified MLR-based tests are unreliable. In financial econometrics, exact tests have been proposed for a few specific hypotheses [Jobson and Korkie (Journal of Financial Economics, 1982), MacKinlay (Journal of Financial Economics, 1987), Gib-bons, Ross and Shanken (Econometrica, 1989), Zhou (Journal of Finance 1993)], most of which depend on normality. For the gaussian model, our tests correspond to Gibbons, Ross and Shanken’s mean-variance efficiency tests. In non-gaussian contexts, we reconsider mean-variance efficiency tests allowing for multivariate Student-t and gaussian mixture errors. Our framework allows to cast more evidence on whether the normality assumption is too restrictive when testing the CAPM. We also propose exact multivariate diagnostic checks (including tests for multivariate GARCH and mul-tivariate generalization of the well known variance ratio tests) and goodness of fit tests as well as a set estimate for the intervening nuisance parameters. Our results [over five-year subperiods] show the following: (i) multivariate normality is rejected in most subperiods, (ii) residual checks reveal no significant departures from the multivariate i.i.d. assumption, and (iii) mean-variance efficiency tests of the market portfolio is not rejected as frequently once it is allowed for the possibility of non-normal errors.