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31.
J. A. Baeza A. A. Braga L. S. López-Greco E. Perez M. L. Negreiros-Fransozo A. Fransozo 《Marine Biology》2010,157(12):2643-2653
One of the main goals of sex allocation theory is understanding sex ratio evolution. However, theoretical studies predicting
sex ratios in species with unusual sexual systems, such as protandric simultaneous (PS) hermaphroditism, are rare. In PS hermaphrodites,
juveniles first develop into functional males that mature into simultaneous hermaphrodites later in life. Here, we report
on the sex ratio (males/males + hermaphrodites) in the PS hermaphroditic shrimp Exhippolysmata oplophoroides. A 2-year study demonstrated that hermaphrodites dominated the population in two different bays. This skewed sex ratio may
be explained by limited encounter rates among conspecifics. In agreement with this idea, the density of shrimps was extremely
low (≤1 shrimp km−2) at the two study sites. Size at sex phase change and sex ratios remained relatively stable through time at the two bays.
The stability of these parameters might be explained by the rather steady population structure of this species during the
study period. A review of sex ratios in PS hermaphroditic shrimps (Lysmata and Exhippolysmata) revealed considerable variation; some species have male- and others hermaphrodite-skewed sex ratios. The conditions explaining
inter- and intra-specific sex ratio variation in protandric simultaneous hermaphroditic species remain to be addressed. 相似文献
32.
From Global to Local: Providing Actionable Flood Forecast Information in a Cloud‐Based Computing Environment
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J. Fidel Perez Nathan R. Swain Herman G. Dolder Scott D. Christensen Alan D. Snow E. James Nelson Norman L. Jones 《Journal of the American Water Resources Association》2016,52(4):965-978
Global and continental scale flood forecast provide coarse resolution flood forecast, but from the perspective of emergency management, flood warnings should be detailed and specific to local conditions. The desired refinement can be provided by the use of downscaling global scale models and through the use of distributed hydrologic models to produce a high‐resolution flood forecast. Three major challenges associated with transforming global flood forecasting to a local scale are addressed in this work. The first is using open‐source software tools to provide access to multiple data sources and lowering the barriers for users in management agencies at local level. This can be done through the Tethys Platform that enables web water resources modeling applications. The second is finding a practical solution for the computational requirements associated with running complex models and performing multiple simulations. This is done using Tethys Cluster that manages distributed and cloud computing resources as a companion to the Tethys Platform for web app development. The third challenge is discovering ways to downscale the forecasts from the global extent to the local context. Three modeling strategies have been tested to address this, including downscaling of coarse resolution global runoff models to high‐resolution stream networks and routing with Routing Application for Parallel computatIon of Discharge (RAPID), the use of hierarchical Gridded Surface and Subsurface Hydrologic Analysis (GSSHA) distributed models, and pre‐computed distributed GSSHA models. 相似文献
33.
Natalie A. Jones Pascal Perez Thomas G. Measham Gail J. Kelly Patrick d’Aquino Katherine A. Daniell Anne Dray Nils Ferrand 《Environmental management》2009,44(6):1180-1195
Participatory modeling is increasingly recognized as an effective way to assist collective decision-making processes in the
domain of natural resource management. This article introduces a framework for evaluating projects that have adopted a participatory
modeling approach. This evaluation framework—known as the “Protocol of Canberra”—was developed through a collaboration between
French and Australian researchers engaged in participatory modeling and evaluation research. The framework seeks to assess
the extent to which different participatory modeling initiatives not only modify perceptions among and interactions between
participants, but also contribute to collective decision-making. The article discusses the development of the framework and
it’s application to three case-studies, two from Australia and one from the Pacific Island of the Republic of Kiribati. The
article concludes with some comments for future use of the framework in a range of participatory modeling contexts. 相似文献
34.
Chlorination of naphthalene by Cl atoms has been studied in the gas phase. The chlorinating agent was produced by γ-radiolysis of tetrachloromethane. At low conversions only monosubstituted products are observed. Both isomers are formed, the yield of 1-chloronaphthalene exceeding that one of its isomer. The extent of the addition reaction increases with the temperature. The relative Arrhenius plot of observed rate constants is linear over the temperature range investigated (60–120 °C) and its slope corresponds to a difference of 11.0 kJ/mol between the activation energies of 2-chloronaphthalene and 1-chloronaphthalene. 相似文献
35.
The sea cucumber fishing crisis in Galapagos is an example of the potential consequences of rapid migration, growing economic competition, and weak regulatory mechanisms. In a short period of time sea cucumber fishing has become the most inflammatory issue in the Galapagos. The key factors that allowed for the efficient exploitation of the new resource were not the fishermen themselves but rather the new fishing techniques and access to credit and markets. This suggests that the annual sea cucumber crisis is due to factors more complex than simply more fishermen generating greater sea cucumber catches. This paper examines census data and fisher registries to analyze population growth in the islands. A public opinion survey is used to determine the population's attitudes toward sea cucumber fishing and regulations. Qualitative interviews explore the history of the sea cucumber boom. Information from the sea cucumber monitoring program provides estimates for the annual sea cucumber catches. 相似文献
36.
Experimental nutrient (N, P, and N+P) additions to shallow (ca. 1 m)Cymodocea nodosa (Ucria) Aschers. stands growing in patches and in a continuous meadow in a Mediterranean Bay (Alfacs Bay, NE Spain) in 1988 demonstrated mid-summer growth to be strongly P-limited, as suggested by the high N:P ratios (>35) in unmanipulated plants. P additions resulted in increased leaf P content, reduced N:P ratios, and enhanced shoot growth and turnover in both populations. These effects promoted in turn a stand response, leading to increased biomass and, therefore, increased areal productivity in the plots receiving P. The stand response was largely attributable to a doubling of shoot density, indicating enhanced rhizome growth and branching. 相似文献
37.
Agent based simulation of a small catchment water management in northern Thailand: Description of the CATCHSCAPE model 总被引:1,自引:0,他引:1
Due to mounting human pressure, stakeholders in northern Thailand are facing crucial natural resources management (NRM) issues. Among others, the impact of upstream irrigation management on downstream agricultural viability is a growing source of conflict, which often has both biophysical and social origins. As multiple rural stakeholders are involved, appropriate solutions should only emerge from negotiation. CATCHSCAPE is a Multi-Agent System (MAS) that enables us to simulate the whole catchment features as well as farmer’s individual decisions. The biophysical modules simulate the hydrological system with its distributed water balance, irrigation scheme management and crop and vegetation dynamics. The social dynamics are described as a set of resource management processes (water, land, cash, labour force). Water management is described according to the actual different levels of control (individual, scheme and catchment). Moreover, the model’s architecture is presented in a way that emphasises the transparency of the rules and methods implemented. Finally, one simulated scenario is described along with its main results, according to different viewpoints (economy, landscape, water management). 相似文献
38.
Photocatalytic degradation of lignin and lignin models, using titanium dioxide: the role of the hydroxyl radical 总被引:8,自引:0,他引:8
The role of hydroxyl radicals on the degradation of lignins during a cellulosic pulp bleaching process including a photocatalytic stage, was assessed using peroxyformic acid lignins EL1 and REL1 and two phenolic niphenyl lignin models 1 and 2. The irradiations were performed in the absence of photocatalyst TiO2 and H2O2 (condition a), in the presence of TiO2 (condition b) and in the presence of H2O2 (condition c). The experiments were conducted in alkaline (pH approximately 11) aqueous ethanol solutions with oxygen bubbling. The relative phenolic content of the irradiated solutions, which is indicative of the involvement of hydroxyl radicals, was determined by ionization absorption spectroscopy. The results obtained show that the catalyzed reaction involves both degradation of the phenolate groups by electron transfer and hydroxylation of the lignin aromatic structure. Benzyl alcohol structural elements in sodium borohydride reduced lignin REL1 and compound 2 were also found as good trapping agents for the hydroxyl radicals. The degradation of EL1 was studied by measuring its fluorescence emission by comparison to the fluorescence of compound 2. The emission spectra indicate that some biphenyl phenolate anions in EL1 are reacting under UV/visible irradiation and some others, probably polyphenolic chromophores emitting less fluorescence, are formed. 相似文献
39.
Rebecca G. Harvey Larry Perez Frank J. Mazzotti 《Journal of Environmental Planning and Management》2016,59(5):789-807
Public engagement is important to invasive species management, and recreational harvest programs are one way agencies seek to involve the public and raise awareness. We surveyed participants (n = 660) and non-participants (n = 77) in the 2013 Python ChallengeTM to understand whether this event achieved its primary goal of raising awareness of the ecological impact of Burmese pythons (Python molurus bivittatus) in south Florida. Respondents indicated a high level of ‘concern’ about the seriousness of the python problem and the need for management actions. Concern was affected positively by environmental motivations, experience of seeing pythons in the wild, older age, and female sex, but negatively by level of Python Challenge involvement. Results suggest that ‘proximate’ experience of not seeing a python may reduce concern, whereas ‘ongoing’ experience may temper concern without diminishing involvement. This research highlights the role of experience in shaping beliefs and advises diligence in public participation programs. 相似文献
40.
Groundwater in the central part of Argentina contains arsenic concentrations that, in most cases, exceed the value suggested
by international regulations. In this region, Quaternary loessical sediments with a very high volcanic glass fraction lixiviate
arsenic and fluoride after weathering. The objectives of this study are to analyze the spatial distribution of arsenic in
different hydrogeological regions, to define the naturally expected concentration in an aquifer by means of hydrogeochemistry
studies, and to identify emergent health evidences related to cancer mortality in the study area. The correlation between
arsenic and fluoride concentrations in groundwater is analyzed at each county in the Cordoba Province. Two dimensionless geoindicators
are proposed to identify risk zones and to rapidly visualize the groundwater quality related to the presence of arsenic and
fluoride. A surface-mapping system is used to identify the spatial variability of concentrations and for suggesting geoindicators.
The results show that the Chaco-Pampean plain hydrogeologic region is the most affected area, with arsenic and fluoride concentrations
in groundwater being generally higher than the values suggested by the World Health Organization (WHO) for drinking water.
Mortality related to kidney, lung, liver, and skin cancer in this area could be associated to the ingestion of arsenic-contaminated
water. Generated maps provide a base for the assessment of the risk associated to the natural occurrence of arsenic and fluoride
in the region. 相似文献