Modeling and analysis of a marine plankton system with nutrient recycling and diffusion

This article describes a nutrient‐phytoplankton‐zooplankton system with nutrient recycling in the presence of toxicity. We have studied the dynamical behavior of the system with delayed nutrient recycling in the first part of the article. Uniform persistent of the system is examined. In the second part of the article, we have incorporated diffusion of the plankton population to the system and dynamical behavior of the system is analyzed with instantaneous nutrient recycling. The condition of the diffusion driven instability is obtained. The conditions for the occurrence of Hopf and Turing bifurcation critical line in a spatial domain are derived. Variation of the system with small periodicity of diffusive coefficient has been studied. Stability condition of the plankton system subject to the periodic diffusion coefficient of the zooplankton is derived. It is observed that nutrient‐phytoplankton‐zooplankton interactions are very complex and situation specific. Moreover, we have obtained different exciting results, ranging from stable situation to cyclic oscillatory behavior may occur under different favorable conditions, which may give some insights for predictive management. © 2014 Wiley Periodicals, Inc. Complexity 21: 229–241, 2015     

Examination of Contemporary Lake Sediments by Means of Thermal Analysis: The Dabie lake near Szczecin

An attempt was made to use thermal analysis (DTA, TG, DTG) for identification of the mineralogical composition of contemporary lake sediments. Sediments were investigated both in the natural state and after ignition at 300°C. Selected fractions of the sediments in the natural state were also studied. The thermoanalytical curves of mollusca shells, reed and plankton were also recorded for use in the interpretation of the thermoanalytical curves of sediments.This revised version was published online in November 2005 with corrections to the Cover Date.     

乌鲁木齐淡水原生动物的种类及分布调查初报

几年来，在对乌鲁木齐淡水浮游生物调查中，对原生动物也作了初步研究．为了对乌鲁木齐的原生动物做一个较为系统的了解，从１９９４年５月～７月在９个样点采集水样，并对分属于植鞭纲、根足纲、辐足纲、寡膜纲、动基片纲及多膜纲等６个纲的１０９种原生物进行了鉴定．同时对各样点的主要生态因素及浮游原生动物的分布特征作了进一步的分析．     

Plankton growth dynamic driven by plankton body size in deterministic and stochastic environments

In this paper, we establish a new phytoplankton–zooplankton model by considering the effects of plankton body size and stochastic environmental fluctuations. Mathematical theory work mainly gives the existence of boundary and positive equilibria and shows their local as well as global stability in the deterministic model. Additionally, we explore the dynamics of V-geometric ergodicity, stochastic ultimate boundedness, stochastic permanence, persistence in the mean, stochastic extinction, and the existence of a unique ergodic stationary distribution in the corresponding stochastic version. Numerical simulation work mainly reveals that plankton body size can generate great influences on the interactions between phytoplankton and zooplankton, which in turn proves the effectiveness of mathematical theory analysis. It is worth emphasizing that for the small value of phytoplankton cell size, the increase of zooplankton body size can not change the phytoplankton density or zooplankton density; for the middle value of phytoplankton cell size, the increase of zooplankton body size can decrease zooplankton density or phytoplankton density; for the large value of phytoplankton cell size, the increase of zooplankton body size can increase zooplankton density but decrease phytoplankton density. Besides, it should be noted that the increase of zooplankton body size cannot affect the effect of random environmental disturbance, while the increase of phytoplankton cell size can weaken its effect. There results may enrich the dynamics of phytoplankton-zooplankton models.     

Planktonic Communities and Chaotic Advection in Dynamical Models of Langmuir Circulation

A deterministic mechanism for the production of plankton patches within a typical medium scale oceanic structure is proposed and investigated. By direct numerical simulation of a simple model of Langmuir circulation we quantify the effects of unsteady flows on planktonic communities and demonstrate their importance. Two qualitatively different zones within the flow are identified: chaotic regions that help to spread plankton and locally coherent regions, that do not mix with the chaotic regions and which persist for long periods of time. The relative importance of these regions to both phytoplankton and zooplankton is investigated, taking into account variations in plankton buoyancy. In particular, species-specific retention zone structure is discussed in relation to variations in environmental forcing.     

An experimental study of acoustic scattering from thermocline in shallow sea

I.IntroductionThetemperature,salinityandstaticprcssureofscawaterchangewithdepth,whichformsthcsoundvelocityvertica1distributioninthesea.Duringsummcrscason,thercaren0n-uniformthermoclinelaycrsinthedepths0fshallowseaal0ngChinacoast.Wearenowabletodeducctheimpedanccproflle(pc)byechoesofacousticwavesfr0mvarioustherm0c1ine1ayers.Thewaterdcnsityvaricsonlyslight1y,hencetheac0usticve1ocityde-Pendsmainlyonthetemperatureofseawatcr,andthercfore,itispossiblctorecordthcdepthofthermoclinelaycrsbyusingacoust…     

Well‐posedness,positivity, and time asymptotics properties for a reaction–diffusion model of plankton communities,involving a rational nonlinearity with singularity

In this work, we consider a reaction–diffusion system, modeling the interaction between nutrients, phytoplankton, and zooplankton. Using a semigroup approach in , we prove global existence, uniqueness, and positivity of the solutions. The nonlinearity is handled by providing estimates in , allowing to deal with most of the functional responses that describe predator/prey interactions (Holling I, II, III, Ivlev) in ecology. The paper finally exhibits some time asymptotic properties of the solutions.     

Fish and Plankton Interplay Determines Both Plankton Spatio-Temporal Pattern Formation and Fish School Walks: A Theoretical Study

The fascinating variety of spatio-temporal patterns in aquatic ecosystems and the understanding of the governing mechanisms of its generation and further dynamics requires ongoing experimental and theoretical studies. After introducing a certain hybrid mathematical model, this paper makes an attempt to demonstrate that the predation of a mobile planktivorous fish school on zooplankton can initiate both plankton pattern formation and fish school walks. Nonlinear interactions in the model of a fish-zooplankton-algae trophic chain prevent a simple intuitive understanding of the system dynamics. It is shown that the fish school predation and motion can give rise to plankton spiral waves. In the course of the spiral wave formation, the amplitudes of the spatially averaged plankton density oscillations are decreasing dramatically. Fish school walks are shown to resemble a fractional Brownian motions with a Hurst exponent depending on the fish predation rate.     

Printed Dielectrophoretic Electrode-Based Continuous Flow Microfluidic Systems for Particles 3D-Trapping

Inkjet-printing is used to fabricate dielectrophoretic electrodes able to trap polystyrene (PS) microparticles as well as model planktonic cells. The possibility of rapid prototyping offered by inkjet-printing allows the rational design of microchannels with tailored electric field distributions experienced by the suspended particles, which in turn provides a handle to drive them towards target regions. Specifically, this goal is achieved using two facing substrates constituting the bottom and the top walls of the channel, with a pair of interdigitated electrodes previously patterned by inkjet-printing on each side. Influence of electrode polarization (magnitude and frequency of the input signal) is investigated both theoretically, by modeling the electric field distribution inside the channel, and experimentally using confocal fluorescence microscopy. The printed device is able to sort circulating PS particles as a function of their size, with diameters ranging from 0.5 to 5 µm, as well as to separate planktonic species according to their composition (Alexandrium minutum versus Prorocentrum micans). This work paves the way for the development of large-area, microstructured dielectrophoretic electrodes able to separate the constituents of samples at flow rates up to 150 µL mn⁻¹.     

赣江中游冬季浮游生物的调查分析

2008年12月对赣江中游进行了浮游生物的调查。鉴定结果如下:浮游植物共8门30属47种,硅藻门30种,绿藻门10种,蓝藻门1种,金藻门2种,裸藻门1种,甲藻门1种,黄藻门1种,隐藻门1种。浮游动物27种,其中轮虫类11种,枝角类8种,桡足类6种,原生动物2种。进行了浮游生物多样性指数M arga lef