Population dynamics of Melanoides tuberculata (Thiaridae) snails in a desert spring,United Arab Emirates and infection with larval trematodes

A dense population of Melanoides tuberculata was found at a brackish (5.93–6.98%) desert spring in the United Arab Emirates. A total of 232–300 snails were measured and examined for larval trematodes during the period January 1990 to January 1991. The relative abundance of various size classes of the snail has shown that the mass release of young snails occurred twice a year, in April–May and September–October. Seven different forms of cercariae were found: A xiphidiocercaria, a brevifurcate cercaria, two pleurolophocercous cercariae, two gymnocephalous cercariae, and the cercaria of Philophthalmus gralli. The overall infection rate of this snail was 73.6% and ranged from 51.3 during February–March 1990 to 91.7% during January 1991. The xiphidiocercaria and the P. gralli cercaria were the most abundant and were found in 21.1% and 29.7%, respectively, of the examined snails. A relatively high rate (9.5%) of double infection was found. Cases of triple infection were also encountered.     

Monte Carlo simulation of branched alkanes and long chain n -alkanes with anisotropic united atoms intermolecular potential

The anisotropic united atoms potential for linear alkanes proposed by Ungerer (J. Chem. Phys. , 112 , 5499, 2000), called AUA4, has been used to predict several equilibrium properties (vapour pressure, vaporisation enthalpies, and liquid densities) of alkanes by Gibbs ensemble Monte Carlo simulation. In order to extend the potential to branched alkanes, potential parameters for the CH group have been determined by optimisation on the basis of equilibrium properties of isobutane, keeping the same parameters as AUA4 for the CH 3 groups. The resulting CH parameters form a regular sequence with those previously determined for CH 3 and CH 2 groups, so that a physically consistent parameter set is obtained. Simulations have been performed at temperatures ranging from 450 to 800 u K for long n -alkanes (C20, C25 and C30) and from 350 to 450 u K for four heptane isomers (n -heptane, 2-methylhexane, 2,4-dimethylpentane and 2-ethylpentane). In order to achieve internal relaxation of long chains with a good efficiency, a specific Monte Carlo move was used in which a united atom is rotated around its nearest neighbours. Equilibrium properties of long chain alkanes are well predicted, and small differences between heptane isomers are represented with a good accuracy. It is concluded that the AUA4 potential shows an interesting degree of transferability.     

The state of ethnicity and the ethnicity of the state: Ethnic politics in Southeast Asia

Attitudes about racial inequality in the United States are often viewed through the lenses of discrimination and disadvantage. However, as whiteness studies suggest, systems of racial inequality produce both disadvantage and advantage. National surveys have documented explanations for African American disadvantage but have not collected data on explanations for white advantage. African American disadvantage and white advantage are two sides of the same coin – racial inequality. To understand attitudes about racial inequality, we need to know Americans' beliefs about both sides of the racialized system. This research uses national survey data to examine explanations for both sides of racial inequality and identifies which factors are believed to be most important in explaining white advantage, finding that racial attitudes are complex and are dependent upon the specific situation and context. This research will provide a valuable contribution to both whiteness studies and race relations research.     

Larval development of two species of barracuda,Sphyraena guachancho andS. tome (Teleostei: Sphyraenidae), from southeastern Brazil

Morphological development of barracudas (Sphyraena guachancho andS. tome) is described, based on larval and juvenile specimens collected in the southeast Brazilian Bight. Preflexion larvae of the two species are similar, butS. tome larvae can be distinguished from those ofS. guachancho by having small melanophores on the midbrain and a row of melanophores along the ventral midline of the lower jaw and isthmus. Flexion and postflexion larvae ofS. tome are more slender than those ofS. guachancho. Morphology and pigment patterns ofS. tome are similar to those ofS. borealis from the north Atlantic. whereasS. guachancho larvae are similar toS. barracuda in having a fusiform body, advanced position of the pelvic fins and a heavily pigmented tail region, but differ in having a fleshy tip on the lower jaw in postflexion and juvenile stages.     

Avian Predation on Steelhead is Consistent with Compensatory Mortality

Numerous factors such as predation, disease, injury, and environmental conditions (e.g., river flows, hydropower operations) can influence survival rates of fish. Although mortality due to predation is commonly assumed to be additive and result in a directly proportional reduction on survival rates, compensatory processes may work to counteract or negate the effects of predation mortality on survival rates. We applied a random effects model to a long-term, mark-recapture-recovery data set on anadromous steelhead (Oncorhynchus mykiss) from the Snake River Basin in the northwestern United States to assess whether avian predation mortality constitutes an additive or compensatory source of mortality. Specifically, our assessment focused on predation mortality due to double-crested cormorants (Phalacrocorax auritus) and Caspian terns (Hydroprogne caspia) on colonies in the Columbia River estuary. In addition, we evaluated several candidate environmental indices to examine potential interactions between the effects of predation versus environmental conditions on steelhead survival rates. Average predation rates were 3.3% for the double-crested cormorant colony and 17.0% for the Caspian tern colony. For both colonies, the estimated correlation between the predation rate and survival rate of steelhead was near zero, indicating that mortality due to avian predation is compensatory. Models that included variables for river flow, juvenile migration timing, and an index of forage biomass in the ocean accounted for 56–59% of the variation in steelhead survival, whereas avian predation rates accounted for <1% of the variation. Management efforts to reduce the abundance of the bird colonies are unlikely to improve the survival or conservation status of steelhead; however, results indicate that steelhead survival could be improved by hydropower management decisions that increase river flows and reduce juvenile migration delays. © 2020 The Wildlife Society.     

The energy embodied in the first and second industrial revolutions

Understanding the nature of energy embodied in economies is essential to assessing their potential to grow or transform sustainably. As the first country to undergo industrialization, study of the United Kingdom during the Industrial Revolution is particularly important for understanding transformational processes. Historical accounts describe how exploitation of Britain's coal reserves supported the evolution of steel production, railways, and other industries; yet reconstructions of the UK's eighteenth/nineteenth century economy have found relatively small contributions from coal mining to economic growth. Here, economic input‐output models for 1841 and 1907 are used to calculate the coal embodied in capital investment, consumption, and exports. Most of the coal was embodied in consumption in 1841, with coal embodied in exports growing particularly fast by 1907. The coal embodied in capital was smaller, but the energy intensity of investment was about four times larger than the energy intensity of consumption. The coal embodied in building the capital stock, much of it used for production of materials such as iron, steel, and bricks, was important for economic growth and transformation. Using historical proxy data, it is estimated that ～1.1 billion imperial tons of coal (34,000 PJ) were used to build the UK's capital assets between 1760 and 1913. The conceptual model developed here helps to explain the role of energy in economic growth and is important to contemporary sustainable development. This article met the requirements for a gold – gold JIE data openness badge described at http://jie.click/badges .     

美国长期生态研究计划三十年:特点、效果与启示——以弗吉尼亚海岸带保护区为例

为观测和理解长时间与大范围尺度的生态变化,美国自然科学基金会于1980年启动了长期生态研究计划(LTER),30年来在站点建设、科学研究和社会服务等方面取得了巨大成就.本文将美国LTER的成功经验归纳为5个特点,即:研究网络、研究主题和数据兼容的系统性,项目时间与研究尺度的长期性,资金来源与研究内容的灵活性,国际、人文、方法与机构合作方面的拓展性,数据和教育的共享性;并以弗吉尼亚海岸保护区(VCR)为案例展示其实施效果.在此基础上提出对我国长期生态研究的建议,包括加强组织建设,建立完整网络并增强站际合作,重视数据的质量、管理和分享,增强多学科研究,扩大公共影响等.     

Midge (Chironomidae,Chaoboridae, Ceratopogonidae) assemblages and their relationship with biological and physicochemical variables in shallow,polymictic lakes

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Declarations and Statements with Respect to the 1982 UNCLOS: Potential Legal Disputes between the United States and China after U.S. Accession to the Convention

This article discusses the implications of U.S. accession to the 1982 United Nations Convention on the Law of the Sea (UNCLOS) for the future development of Sino-American relations in the areas of ocean law and politics. The declarations and understandings contained in the Senate Resolution of Advice and Consent to U.S. Accession to the UNCLOS are examined in detail in the context of previous maritime conflicts between the United States and China.     

Navigation in Marine Protected Areas: National and International Law

Abstract

World fish resources, fishing methods, and processing operations in the seafood industry are described. The fishery situation in developing countries (LDCs) is discussed, with particular reference to artisanal and other local fisheries, and examples are cited to illustrate the structure of the industry. Technology transfer from developed countries to LDCs is discussed and recommendations are presented for future technology transfer programs. It is concluded that an integrated complex of small projects with defined, attainable objectives and immediate impact on income and food supply of the LDC populations is likely to be more successful than large‐scale programs with little immediate payoff. A case study of fisheries in two developing countries, Thailand and Peru, and extensive tabulation of statistical data on catches, value of catch, and unit value of fish species groups for selected countries, with a discussion of the significance of the data, are presented in an appendix.