Spatial variability of E. coli in an urban salt-wedge estuary

This study investigated the spatial variability of a common faecal indicator organism, Escherichia coli, in an urban salt-wedge estuary in Melbourne, Australia. Data were collected through comprehensive depth profiling in the water column at four sites and included measurements of temperature, salinity, pH, dissolved oxygen, turbidity, and E. coli concentrations. Vertical variability of E. coli was closely related to the salt-wedge dynamics; in the presence of a salt-wedge, there was a significant decrease in E. coli concentrations with depth. Transverse variability was low and was most likely dwarfed by the analytical uncertainties of E. coli measurements. Longitudinal variability was also low, potentially reflecting minimal die-off, settling, and additional inputs entering along the estuary. These results were supported by a simple mixing model that predicted E. coli concentrations based on salinity measurements. Additionally, an assessment of a sentinel monitoring station suggested routine monitoring locations may produce conservative estimates of E. coli concentrations in stratified estuaries.     

On the feasibility of studying the exospheres of Earth-like exoplanets by Lyman-<Emphasis Type="Italic">α</Emphasis> monitoring

Observations of the Earth’s exosphere have unveiled an extended envelope of hydrogen reaching further than 10 Earth radii composed of atoms orbiting around the Earth. This large envelope increases significantly the opacity of the Earth to Lyman α (Lyα) photons coming from the Sun, to the point of making feasible the detection of the Earth’s transit signature from 1.35 pc if pointing with an 8 meter primary mirror space telescope through a clean line of sight (N _H <?10¹⁷ cm^??2), as we show. In this work, we evaluate the potential detectability of Earth analogs orbiting around nearby M-type stars by monitoring the variability of the Lyα flux variability. We show that, in spite of the interstellar, heliospheric and astrospheric absorption, the transit signature in M5 V type stars would be detectable with a dedicated Lyα flux monitor implemented in a 4–8 m class space telescope. Such monitoring programs would enable measuring the robustness of planetary atmospheres under heavy space weather conditions like those produced by M-type stars. A 2-m class telescope, such as the World Space Observatory, would suffice to detect an Earth-like planet orbiting around Proxima Centauri, if there was such a planet or nearby M5 type stars.     

Analysis of occurrence patterns and biological factors of cetaceans based on long‐term and fine‐scale data from platforms of opportunity: Madeira Island as a case study

Management and conservation issues are addressed through the identification of areas of particular importance, which requires the acquisition of baseline information on species distribution and dynamics. These types of data are particularly difficult to obtain at high resolution for large marine vertebrates like cetaceans, given that dedicated surveys are complex and logistically expensive. This study uses daily presence–absence sighting data of cetaceans collected year‐round from whale‐watching boats to support the theory that fine‐scale data obtained from platforms of opportunity can provide valuable information on species occurrence and group dynamics. Data from 7,551 (daily) sightings comprising 22 species were collected from 3,527 surveyed days over 11 years (mean of 321 days per year, SD = 17) in the pelagic environment of Madeira Island. Cetaceans were observed on 92% of the surveyed days, and a mean of 15.4 (SD = 1.5), 8.2 (SD = 2.0) and 2.1 (SD = 1.2) species were recorded per year, month, and day, respectively. There were significant differences in the number of species per month (p < .001), with the highest diversity recorded in June. At least nine species, comprising 96% of all sightings, were found to use the Madeiran waters on a regular basis, such as the Atlantic spotted dolphin (Stenella frontalis), the short‐beaked common dolphin (Delphinus delphis), the bottlenose dolphin (Tursiops truncatus), and others featured in the Red List of the International Union for Conservation of Nature as Endangered, Vulnerable, and Data Deficient. In addition, 10 species were found to use the Madeiran waters for travelling, feeding, resting, socializing and calving, which suggests that the southern and southeastern waters of Madeira Island constitute an area of interest for cetaceans. This study characterizes the cetaceans’ community structure (occurrence, aggregation sizes, behaviours, proportion of calves, and inter‐specific relationships) of a poorly studied region, providing important information for managers. Finally, the advantages and limitations of using fine‐scale data from a type of platform of opportunity that is increasing along coastlines globally are discussed.     

The effects of urbanization on ecosystem services for biodiversity conservation in southernmost Yunnan Province,Southwest China

Journal of Geographical Sciences - Urbanization can profoundly influence the ecosystem service for biodiversity conservation. However, few studies have investigated this effect, which is...     

基于电流理论识别多物种扩散廊道的优先度——以西南西双版纳为例（英文）

Ecological corridor networks can efficiently improve regional landscape connectivity. Corridors for multiple faunal species movements are receiving increasing attention and graph theory is considered a promising way to explore landscape connectivity. In Xishuangbanna, the circuit theory was applied to explore the corridor networks for biodiversity for the first time. In addition, disturbances caused by the road network and the protection efficiency of National Nature Reserves and planned area for corridors were evaluated. Results indicated that the regional corridor networks could be estimated using a modified circuit method and Zonation model. Spatially, the key corridors were concentrated in the central-western, southeastern and northern regions. We detected 66 main intersections between key corridors and the road buffer. Of these points, 65% are forest, 23% grassland and 12% farmland. More than half of the area of National Nature Reserves constituted the top 50% of the corridors, and the planned corridor areas could efficiently protect some key corridors. However, these reserves only protected about 17% of regional key corridors, and the corridor conservation area in the western and northern regions were absent. The issues addressed in our study aided in the elucidation of the importance of regional landscape connectivity assessments and operational approaches in conservation planning.     

Assessment of coastal management options by means of multilayered ecosystem models

This paper presents a multilayered ecosystem modelling approach that combines the simulation of the biogeochemistry of a coastal ecosystem with the simulation of the main forcing functions, such as catchment loading and aquaculture activities. This approach was developed as a tool for sustainable management of coastal ecosystems. A key feature is to simulate management scenarios that account for changes in multiple uses and enable assessment of cumulative impacts of coastal activities. The model was applied to a coastal zone in China with large aquaculture production and multiple catchment uses, and where management efforts to improve water quality are under way. Development scenarios designed in conjunction with local managers and aquaculture producers include the reduction of fish cages and treatment of wastewater. Despite the reduction in nutrient loading simulated in three different scenarios, inorganic nutrient concentrations in the bay were predicted to exceed the thresholds for poor quality defined by Chinese seawater quality legislation. For all scenarios there is still a Moderate High to High nutrient loading from the catchment, so further reductions might be enacted, together with additional decreases in fish cage culture. The model predicts that overall, shellfish production decreases by 10%–28% using any of these development scenarios, principally because shellfish growth is being sustained by the substances to be reduced for improvement of water quality. The model outcomes indicate that this may be counteracted by zoning of shellfish aquaculture at the ecosystem level in order to optimize trade-offs between productivity and environmental effects. The present case study exemplifies the value of multilayered ecosystem modelling as a tool for Integrated Coastal Zone Management and for the adoption of ecosystem approaches for marine resource management. This modelling approach can be applied worldwide, and may be particularly useful for the application of coastal management regulation, for instance in the implementation of the European Marine Strategy Framework Directive.     

The Rotation of a Non-Rigid, Non-Symmetrical Earth II: Free Nutations and Dissipative Effects

The study of the rotation of a non-rigid, non-symmetrical Earth with a heterogeneous and stratified liquid core was recently accomplished by González and Getino (1997) through the Hamiltonian formalism. In this work that model is extended by including the effect of the dissipation arising from the mantle–core interaction due to the viscous and electromagnetic coupling. A canonical transformation to a new set of non-singular variables is performed, in order to avoid small divisors in the system of equations. Numerical estimations of the effect of the dissipation are given in form of tables and graphics, and the significance of this effect is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Behaviour of a new type of Runge–Kutta methods when integrating satellite orbits

Recently, González, Martín and Farto have developed new numerical methods (RKGM methods) of Runge–Kutta type and fixed step size for the numerical integration of perturbed oscillators. Moreover, it seems natural to study the behaviour of these new methods for the accurate integration of orbital problems after the application of linearizing transformation, such us KS or BF due to the fact that in these variables, the structure of the problem is of the form of perturbed oscillators, for which the methods constructed are indicated. In this paper, we check the efficiency of these new methods when integrating the satellite problem. The RKGM methods show a very good behaviour when they compete with other, classical and special, methods. This revised version was published online in July 2006 with corrections to the Cover Date.     

Population biology of the portunid crab Callinectes arcuatus Ordway in the Gulf of Nicoya,Costa Rica,Central America

Tropical blue crabs Callinectes arcuatus were collected by trawling in the Gulf of Nicoya on the Pacific coast of Costa Rica, Central America. The gulf population was generally dominated by females. Adult females were common in the upper, more estuarine regions of the gulf during rainy season, but appeared to migrate to the lower gulf during dry season for spawning. Biomass varied with seasonal changes in abundance, but was generally similar to biomass of C. sapidus in Chesapeake Bay. Analysis of size frequency indicated that the population is numerically dominated by adults during January and February and that juveniles are common during the remainder of the year. Extrapolation of available data suggests that female crabs reach maturity in approximately one year after hatching.