一类具有收获率的捕食与被捕食系统

捕食者之间为获取食物开展竞争的捕食与被捕食系统通常用ratio-dependent捕食与被捕食系统描述。本文讨论这类系统在有人为开发（即有常数收获率）时，系统的持久性问题，通过常微分方程的定性分析，得到为保持生态平衡，人为开发的最大上界。     

一类推广的Leslie-Gower型捕食-被捕食模型的动力学性质研究

探讨了一类推广的Leslie-Gower型捕食-被捕食模型的动力学性质。以HollingII型功能反应和推广的Leslie-Gower模式为基础建立了无时滞和有时滞的捕食-被捕食种间作用模型;分析了无时滞模型共生平衡点的稳定性和Hopf分支,得到了共生平衡点的稳定性条件,找到了使系统发生Hopf分支的参数临界值,建立了系统存在稳定极限环的条件;分析了时滞模型系统共生平衡点的渐近稳定性以及孕育时滞参数值变化对模型系统共生平衡点稳定性的影响,找到了时滞模型系统发生Hopf分支的参数临界值,证明了当时滞参数在临界值附近变化时,系统也将发生Hopf分支。     

环境污染中三维捕食_被捕食系统生存和绝灭的阈值

研究了一类受环境污染的3种群系统,得到了三维捕食_被捕食系统持续生存与绝灭的阈值,并由此对系统的正平衡点的稳定性进行了分析。     

一类具污染的捕食与被捕食者模型的研究

利用积分均值法,研究了一类具污染的捕食与被捕食者模型,得到了各种群平均持续生存与绝灭的阈值。     

一类捕食者—被捕食者种群模型的定性分析

利用常微分方程的定性理论,研究了两个种群具有非线性密度制约的捕食-被捕食者系统:dxdt=b0x(b1+b2x-b3x2)-b4xy,dydt=-cy+(αx-βy)y,的平衡点的性质,并证明了该系统存在唯一极限环的一个充分必要条件。     

一类食饵为Smith增长模型且基于比率的食饵-捕食模型的定性分析

研究一类食饵的增长为Smith模型且基于比率和具有第Ⅱ类功能性反映的捕食一食饵系统,对系统进行了稳定性分析,得到了奇点渐近稳定的条件和极限环存在的条件,并指出,系统的持续生存不仅与参数有关,还与其初值有关。     

一类捕食者——被捕食者种群模型的定性分析

利用常微分方程的定性理论，研究了两个种群具有非线性密度制约的捕食-被捕食者系统：dx/dt=box（b1＋b2x-b3x^2）-b4xy，dy/dt=-cy＋（ax-βy）y，的平衡点的性质，并证明了该系统存在唯一极限环的一个充分必要条件。     

一类具群体防御状态及Holling Ⅲ型功能反应的捕食系统正周期解的全局吸引性

应用微分方程比较原理,重合度理论中的Mawhin’s延拓定理和Lyapunov函数研究一类具有相互干扰和群体防御状态及Holling Ⅲ型功能反应的捕食系统正周期解的存在性和全局吸引性。推广了有关文献的研究和结果。     

西峡国土资源系统2007年度精神文明创建工作硕果累累

2007年度,西峡县国土资源系统坚持以科学发展观和构建社会主义和谐社会为指导,广泛深入开展了文明系统、文明单位创建活动,取得了显著成效。该县局被南阳市委、市政府授予“市级标兵文明单位”,该系统被县委、县政府授予“2007年度县级文明系统”,局属土地开发整理中心,国土资源评估事务所两个二级单位及西坪、寨根、石界河、军马河,二郎坪,城关等6个国土资源所同时被西峡县委,县政府授予“2007年度县级文明单位”。     

大连地下水开发模式探讨

为探讨提高大连地区水资源利用率的方法，通过分析总结大连地区滨海水文地质条件，剖析了地下含水系统的独立流域特征、开发价值特征、流动系统特征和环境水文地质的脆弱性特征。在此基础上，提出了大连水资源开发应以流域开发为指导思想、以地下水库为技术方法的加大开发地下水水资源利用模式，并进一步得出岩溶含水系统与河谷砂砾石堆积具有较大开发潜力而基岩裂隙含水系统开发难度较大的结论。     

Feeding ofAcanthocylops robustus on zooplankton

Feeding of freshwater cyclopoid copepodAcanthocyclops robustus on zooplankton was examined by a senes of feeding experiments during August–September of 1993. Study results showedA. robustus can capture and eat all type items provided from the Stary Haklovsky fishpond, a shallow eutrophic water body near Budějovice City, Czech Republic. Selection by the predator was determined largely by prey body-size and density, but was also affected by prey types. Variable but significant changes in feeding rates were found in various size distribution and concentration of prey types. Percentages of small (80–235μm) and large (445–610μm) prey consumed were 42.47 and 3.85%, respectively. Starvation did not cause statistically significant difference. The feeding onCeriodaphnia quadrangula showed significant difference between large and small prey. Feeding rate increased with increasing prey concentration.     

Sensory bases and the mode of feeding behavior of tongue sole <Emphasis Type="Italic">Cynoglossus semilaevis</Emphasis>

We conducted behavior experiments on the roles of vision, olfaction, and the lateral line in feeding in tongue sole Cynoglossus semilaevis Günter. Chemical cues from the prey alone could not elicit any searching or attacking behavior by the fish; only when moving foods were presented, the chemical nature of the foods affected feeding. In addition, we found that normal tongue sole did not accurately recognize moving artificial prey of different shapes. Neither chemosense nor vision plays an important role in prey detection. Reactions to moving objects and the response of the oropharyngeal cavity to different foods showed that the (eyeless) tongue sole use mainly the lateral line for prey detection and capture. Gustation in the oropharyngeal cavity is essential for the fish to swallow its prey.     

Field and laboratory observations on predation and prey selectivity of the scyphomedusa Chrysaora cf. caliparea in Southeast Indian waters

Chrysaora cf. caliparea, one of the most abundant medusae species in India, seems to be an important predator in the coastal waters of Bay of Bengal. The ability of Chrysaora cf. caliparea to feed at maximum rate in high prey concentrations implies that this jellyfish can efficiently exploit dense prey patches, at least for a short period. This study presents preliminary information regarding digestion and feeding rate upon copepods in a warm water environment. The ingestion rate of the average-sized medusae Chrysaora cf. caliparea is well balanced in nature, which in turn implies that this jellyfish is tuned for optimal utilization of available prey resources. Comparison with earlier research indicates that prey escape speed is one important factor governing which prey will be captured. A full understanding of predation mechanics awaits further investigation of both predator and prey behavior. However, because of the scarcity of long-term quantitative population data most insights have to be made indirectly. Nevertheless, low abundance of Chrysaora cf. caliparea in the water column during summer (May 2007) and the overall annual abundance seem not to considerably affect the zooplankton population, especially copepods. The present work contributes to the knowledge of prey-predator relationship of the forgotten fauna in Indian waters, which is especially crucial for understanding the process of ecological recovery of coastal water environment.     

Comparison in nutritional quality between wild and cultured cuttlefish Sepia pharaonis

In this study, the proximate composition and the amino and fatty acid profi les of shrimp Litopenaeus vannamei(prey) and wild and cultured cuttlefi sh Sepia pharaonis(the latter fed the prey) were determined and compared with FAO/WHO recommendations. The resulting scores for isoleucine, phenylalanine+tyrosine, histidine, lysine, threonine, and tryptophan in cultured cuttlefi sh were ≥150. The ratio of EAA(essential amino acids)/nonessential amino acids in cultured cuttlefi sh(0.82) was higher than in the wild form(0.80). All EAA amino acid scores for cultured cuttlefi sh were higher than their wild counterparts, except for histidine and tryptophan. Both groups of cuttlefi sh possessed similar saturated fatty acid content, with the cultured containing much more total(Σ) monounsaturated fatty acids, Σ n-6 polyunsaturated fatty acids(PUFA), and eicosapentaenoic acid(C20:5 n-3) but less Σ n-3 PUFA, arachidonic acid(C20:4 n-6), and docosahexaenoic acid(C22:6 n-3) than their wild counterparts. Therefore, the present results suggest that these cultured cuttlefi sh were better than the wild form for human health. Notably, these results also indicate that the nutritional composition of these cuttlefi sh might have been signifi cantly affected by diet.     

Feedback control for ecosystem management: The case of wolf-elk-hunting dynamics in the US Mountain West

The purpose of this paper is to explore the promise of utilizing some relatively new feedback control techniques in ecosystem management. First, we set forth a basic ecological-economic model of a predator-prey-hunting system in which both the predator and prey have use(flow) and non-use(stock) value and when the predator can inflict transboundary damages. We then use new data from the US Mountain West to show how a particular feedback approach—linear parameter-varying(LPV) control—can be utilized in this context. Our LPV model is able to quantify the cost of managing disturbances that inevitably arise as a manager tries to keep the actual path of the system "close" to its optimum. The results suggest management strategies in mountain ecosystems that feature large, mammalian carnivores.     

Functional morphology of the olfactory organ of the tongue sole, Cynoglossus semilaevis

The morphology and structure of the olfactory organ of Cynoglossus semilaevis Günther are described. The oval olfactory sacs on both sides differ in size and in the number of lamellae, with those on the abocular side having smaller sacs and fewer lamellae than those on the ocular side. On the ocular side, the average ratio of sac length to eye diameter is 2.1 (i.e.>1) with an average of 91 lamellae, while on the abocular side, the values were 1.7 (i.e.>1) and 69, respectively. In addition, the surface morphology varies in different parts of the lamella. The frontal part, near the anterior nostril, is a non-sensory margin with cilia-free epidermal cells. Within this is an internal ciliated sensory area, which is intercalated with ciliated receptor cells and a few ciliated non-sensory cells. Additionally, some dense ciliated non-sensory cells make up a non-sensory area, which also contains cilia-free epidermal cells distributed in patches. In the rear of the olfactory sac near the posterior nostril, the lamellae differ in morphology from those of the frontal olfactory sac but are similar in having few ciliated receptor cells. In other words, the surface of the lamellae in the rear part of the olfactory sac is mainly non-sensory. At present, four types of lamellae (I, II, III and IV) have been recognized in relation to the pattern of the sensory epithelium. In this study, the frontal and rear lamellae resembled types I and IV, respectively, but are referred to as types I′ and IV′ because they are slightly less developed. Data on the ratio of length of lamellae to eye diameter, number of lamellae and the type of surface pattern of the lamellae show that the development of the olfactory system of C. semilaevis facilitates prey capture.     

Feeding habits and ontogenetic diet shifts of Bombay duck,Harpadon nehereus

Based on two bottom trawl surveys conducted in autumn 2000 and 2001, a total of 1106 stomach samples of Bombay duck Harpadon nehereus between 23–278 mm fork length were collected and analyzed. The results show that Bombay duck prey items consisted of 11 groups or 32 species, of which Apogon lineatus, Leptochela gracilis, Acetes chinensis, and Euphausia pacifi ca were the dominant prey species. Ontogenetic variations were found in feeding habits and feeding activity of Bombay duck. Feeding activity was highest in fi sh smaller than 50 mm, lowest in fi sh between 50 and 99 mm, and then increased with increasing size thereafter. As Bombay duck size increased, fi sh prey increased in importance, whereas euphausiids and decapods decreased in importance. Different trophic guilds were observed in feeding habits across the examined size range. Bombay duck smaller than 50 mm were zooplanktivores, mainly feeding on zooplankton and fi sh larva; those between 50 and 149 mm were generalist predators, mainly feeding on pelagic shrimps, demersal shrimps and fi shes; and those larger than 150 mm were piscivores, mainly feeding on fi shes.     

Experimental clearance rates of Aurelia coerulea ephyrae and medusae,and the predation impact on zooplankton in Jiaozhou Bay

The population explosion of jellyfish Aurelia coerulea occurred in Jiaozhou Bay,China in 2009.The potential predation impact of A.coerulea on zooplankton was investigated.Population clearance potential and residence time(t_(1/2)) for copepods were calculated from laboratory clearance rates and measurements of jellyfish size and abundance from May to August 2009 in Jiaozhou Bay.Clearance rates varied widely with prey organisms,but they were not significantly different among various prey concentrations.Medusae captured rotifers,fish larvae and hydromedusae more efficiently than fish eggs,copepods and chaetognaths.Ephyrae captured rotifers and hydromedusae more efficiently than fish larvae and copepods.Clearance rate linearly increased with the cro s s sectional area of A.coerulea(size from 0.3 to7.1 cm).Water temperature also had a marked effect on clearance rate and this was related to the increased beat freque ncy as water temperature increased.In early May 2009,A.coerulea potentially cleared the volume of water in the Bay less than 0.001 times a day,but this value was estimated to be more than 0.3 times a day in July.The t_(1/2) for copepods was less than 6 d in June and July.Abundances of copepods,hydromedusae and chaetognaths were extremely low in 2009 compared to 2008 and 2010(jellyfish non-bloom years).Large predation pressure by the A.coerulea population occurred to control zooplankton communities in Jiaozhou Bay.A.coerulea,when present at a high population level,can be a keystone species in Jiaozhou Bay and control the trophic structure here.     

Medusa consumption and prey selection of silver pomfret Pampus argenteus juveniles

The current study explored Aurelia aurita and Rhopilema esculent um consumption by silver pomfret juveniles, as well as their prey selection between the two jellyfi sh species. Silver pomfret juveniles weighing 1±0.1 g actively preyed on both the species. Their daily A. aurita consumption was 11.6 times their own body weights regardless of the size of A. aurita medusae. Their daily R. esculent um consumption was 13, 9.1, 5, and 4.1 times their own body weights when the R. esculentum medusae were 10, 20, 30, and 40 mm in bell diameter, respectively. The survival rates of the R. esculent um were higher than those of the A. aurita. When the R. esculent um medusae were more than 30 mm in bell diameter, their survival rate exceeded 92%. Silver pomfrets serve as a type of potential predators on A. aurita in coastal waters, and they have little infl uence on R. esculent um with a size exceeding 30 mm. Besides, A. aurita may be able to be used as fi sh prey in silver pomfret artifi cial breeding.