Cannibalism in the lifeboat �� collective movement in Australian plague locusts

Mass migration of locusts is an economically devastating and poorly understood phenomenon. Locust mass migration often follows rapid population growth because individuals must move to find new sources of locally depleted resources. In Mormon crickets and Desert locusts, cannibalistic interactions have been revealed as the driving force behind collective mass movement. Locusts are known to compensate for nutrient deficiencies and they themselves are a good source of nutrients such as protein. However, direct empirical evidence for an adaptive benefit of cannibalism in migratory bands has been lacking. Here, we first show that Australian plague locusts, Chortoicetes terminifera, will cannibalise vulnerable conspecifics to compensate for protein deprivation, supporting the notion that cannibalistic interactions among nutritionally deprived individuals drives collective mass movement. We then show that individuals in a group with the opportunity to cannibalise survive longer and move more than individuals without the opportunity to cannibalise. These results provide empirical support for the ??lifeboat mechanism??, which proposes that cannibalism offers the dual benefits to individuals in a group of surviving longer and travelling farther than a solitary individual without the opportunity to cannibalise.     

Mesoscale circulation in the surface layer off the southern and western Sardinia Island in 2000–2002

Five oceanographic cruises were organized in the Sardinian Sea and Channel in May 2000, March 2001, September 2001, May 2002, and November 2002 to study the characterization of the water masses, Atlantic Water (AW) and Winter Intermediate Water (WIW), and their mesoscale variability. In the Sardinian Channel, an Algerian anticyclonic Eddy (AE) was observed in May 2000, along the Tunisian coast. This induced a greater minimum salinity in a wider and deeper layer than in November 2002, when no AE was observed. Some WIW was observed below it; nevertheless, no link could be established between AEs and WIW occurrences. In the Sardinian Sea, two AEs were observed during spring 2000, and a further two during spring 2002. One AE strongly influenced shelf circulation, in contrast to the other three that were off the continental slope. In the same area, during the end of September 2001, a vertical salinity inversion occurred in the first 30–50 m of depth over the whole sampling field, and a W–NW wind induced a coastal upwelling over the western Sardinian coast (south of 41° N). This upwelling increased the salinity from ～20 to 30 m below the surface to the surface and, thereby led to a lower salinity close to the coast than offshore. This was in contrast to a classical upwelling. Consequently, in the Sardinian Sea, the general circulation, mainly driven by AEs, can meet the coastal wind-driven circulation.     

Analysis of the ph in Europe during the period 1986–1997

The annual averages (1986–1997) of pH are analysed for the most important European Monitoring and Evaluation Programme stations in Europe. The first objective is to discover the different temporal patterns and trends for the pH. To do this, a cluster analysis is developed. The trends are analysed by linear regression for the annual averages. In general, the pH shows an increasing trend significant at 0.05 level and the annual change ranging from +0.01 to +0.05 pH‐units per year for the different clusters obtained. The second objective is to examine the spatial variability of pH in precipitation through the use of principal component analysis. Six statistically significant modes of variability are obtained for the pH which represent the 84.5% of the total variance.     

Trace metals in the western Mediterranean Sea∗

Data on Cd, Pb and Cu concentrations in seawater referring to five years of field studies on the western Mediterranean Sea are reported in order to present a space and time integrated situation on the levels of these metals. Surface total metal concentrations present rather homogeneous distributions between the different areas considered, including the Tyrrhenian Sea. The metal concentrations in three areas affected by natural and industrial wastes are also discussed. The vertical distribution of the dissolved Cd, Pb and Cu in the Alboran Sea seems to be rather homogeneous, both vertically and among the stations chosen between the Strait of Gibraltar and the Island of Alboran.     

Problems of the coasts erosion in the North–Eastern Black Sea Region

The seacoasts protection does not stand standard solutions. Every part of a shore needs to be creatively approached and its hydrodynamic, lithodynamic, geological, geomorphological and other peculiarities must be thoroughly studied for each particular situation. It takes a complex scientific approach considering not only local features, but also the reaction of the whole lithodynamic system in limits of which the coast protective activity is planned with consideration of calculated hydrodynamic parameters (waves, sea level, etc.).     

β-glucanase activity in the seastar Pisaster ochraceus

Specimens of Pisaster ochraceus, an intertidal carnivorous seastar, were collected in northern Puget Sound at Post Point, near Bellingham, Washington, USA, in November 1993, and used in experimentation through September 1994. Ammonium sulfate fractions (60% precipitates) from excised pyloric caeca (digestive glands) possessed -glucanase activity directed toward such -linked substrates as carboxymethylcellulose (CMC), partially-digested cellulose (cellodextrins) and the synthetic substrate p-nitrophenyl--D-glucoside (PNDG). pH-activity and pH-stability maxima were at pH 6 and 5, respectively. No hydrolytic activity was detectable on native cellulose, native chitin or on cationic-modified celluloses such as DEAE-cellulose. Gel filtration (Sephadex G-100) of this 60% precipitate followed by DEAE-Sephadex column chromatography revealed heterogeneity of -glucanase activity, with an indication of up to 11 distinct fractions with variable activity directed toward the substrates indicated above (CMC, cellodextrins and PNDG). These fractions displayed differing ratios of hydrolytic activity on these substrates. None of the isolated fractions displayed activity toward either native cellulose or native chitin. Gut extracts from the edible mussel (Mytilus edulis), a common prey species of P. ochraceus, were shown to possess partially digested cellulose (cellodextrins). These cellodextrins were further degraded by seastar -glucanases in vitro. The digestion of the gut contents of ingested prey provides a possible adaptive explanation for the presence of -glucanase activity in a carnivore.     

Contributing institutional factors of rural environmental pollution in the process of modernization in China —In the perspective of the efficiency of environmental management system

With the development of rural pollution, its characteristic and institutional factor should be studied for pollution control through economics and sociology. Based on the data gathered from investigations by several government sectors, rural environmental pollution can be divided into two types by its sources: internal source type and external source type. The internal source type is the main component of rural pollution at present, which can be further divided into three types. Research shows that the contributing institutional factors of rural pollution issues and the effectiveness of environmental management system over rural pollution can be summarized as distinctiveness. In essence, the rural pollution issue results from the dualism of rural and urban areas’ inadaptability to rural modernization. In detail, the contributing factors can be summed up on three institutional levels. There are obvious loopholes in rural environmental management system which, in the meantime, is incapable and inadaptable to rural pollution control. There exist similar questions in the related public service system, which are intensified by inappropriate reform which brought about incompatible incentive in the recent years. However, in the eleventh five-year plan period, there are advantageous trends in the three institutional levels.     

Statistical interpolation model for the description of ground pollution due to the TCDD produced in the 1976 chemical accident at seveso in the heavily contaminated zone “A”;

The influence of NTA on chromium genetic activity was studied in the D7 strain of Saccharomyces cerevisiae. At low dose (subgenotoxic) of sodium chromate (CrVI) (5mM), NTA increased the point mutation while at higher dose (25 mM) of chromate in the presence of NTA a decrease of point reverse mutation was observed. Probably NTA affected either the uptake of Cr(VI) favouring the intracellular reduction to Cr(III), or the recombinational repair of DNA breaks induced by chromate oxiding activity.

An increase of point (reverse) mutation was obtained in the experiments with NTA and chromium chloride, suggesting the hypothesis that NTA might interact with Cr(III) forming NTA‐Cr(III) complexes able to permeate cellular membranes and bind to DNA. In addition NTA genetic inactivity was confirmed.     

Canopy interception of atmospheric chloride ion during precipitation processes in the subalpine Picea asperata plantation in the upper reaches of the Yangtze River北大核心CSCD

Increasing concentrations of chloride ions (Cl-) in the atmosphere is one of the most important global environmental factors influencing processes in terrestrial ecosystems. To understand the roles played by plantations in intercepting atmospheric Cl- in mountainous regions, a one-year field observation of precipitation and throughfall was conducted in a subalpine artificial Picea asperata plantation in western Sichuan and the dynamics of Cl- concentrations in rainfall, snowfall, and throughfall, and canopy interception on atmospheric Cl- were investigated from August 2015 to July 2016. During the observational year, 27 rainfalls and 6 snowfalls were observed and sampled. The average concentration of Cl- in the precipitation was 1.33 mg/L and the average concentrations of Cl- in rainfall and snowfall were 1.41 mg/L and 0.98 mg/L, respectively. Correspondingly, the total input of Cl- by the precipitation processes was 7.56 kg/hm2, which included 6.31 kg/ hm2 by rainfall and the remainder by snowfall. In one entire year, the total canopy interception of Cl- was 2.61 kg/hm2 and the average interception rate was 38.08%. During the rainy season, the canopy interception of Cl- was 2.20 kg/hm2 and the average rate was 38.90%, whereas during the snow season, the canopy interception of Cl- was 0.41 kg/hm2 and the average rate was 34.39%. The maximum and minimum interception rates occurred in August and September, respectively. Significantly negative correlation was found between the interception rate of Cl- and precipitation. In summary, the P. asperata plantation in the subalpine forest region of western Sichuan exerts an important role in intercepting atmospheric Cl-, which is of great significance for maintaining and improving the environment of the water conservation region in the upper reaches of the Yangtze River. Furthermore, changes in the precipitation pattern caused by global changes might affect the role of the artificial forest canopy interception on atmospheric Cl-. © 2018 Science Press. All rights reserved.     

Two distinct forms of the chitin-degrading enzyme N-acetyl-β-d-glucosaminidase in the Antarctic krill: specialists in digestion and moult

In the Antarctic krill Euphausia superba two forms of the chitinolytic enzyme N-acetyl-β-d-glucosaminidase (NAGase, EC 3.2.1.52) have been described, previously identified as NAGase B and NAGase C. Here, we demonstrate the organ-specific distribution and physiological relevance of both forms using a polyclonal antibody preparation which allows them to be distinguished immunologically. While NAGase B was localized in the integument and displayed a pattern of activity related to the moult cycle, the activity of NAGase C was independent of the moult cycle and was predominantly found in the gastrointestinal tract. Accordingly, NAGase B played a significant role in chitin degradation during the krill's moult, whereas NAGase C participated in the digestion of chitin-containing dietary components. Chromatographic elution profiles of isolated organs confirmed the immunological results by displaying characteristic organ-specific patterns in NAGase activity. The molecular characteristics of the moulting form, NAGase B, may further indicate a vesicular transport of moulting enzymes from the epidermis into the ecdysial space. Based on our results we develop a hypothesis explaining the concurrent processes of simultaneous chitin degradation and chitin synthesis occurring during moult. Received: 30 December 1998 / Accepted: 23 April 1999     

Inorganic pollution in water—the analyst's viewpoint†

Inorganic pollution comprises both major and minor constituents, although only 12 chemical elements may be considered major components. Twenty‐eight elements constitute a group of common minor elements and an additional 13 elements comprise a group of less common minor constituents. Reliable quantitative data are required on the occurrence of these substances in a wide variety of water types, usually at extremely low concentrations. The analysis of standard reference water samples provides information on the overall reliability of water‐quality data. Although most major constituents may be determined with acceptable reliability, determinations of certain minor constituents lack comparable precision; for example, determinations of boron, nickel, and chromium. Few precision data are available on the determination of the less common trace elements. Several comparatively new analytical techniques, such as flameless atomic absorption spectrophotometry, voltammetry, and emission spectroscopy with plasma excitation, appear capable of providing improved sensitivity.     

Transport of butyltins at the water‐air interface and the adsorptive behavior of tributyltin in the surface microlayer

The transfer dynamics and enrichment phenomena of monobutyltin chloride(MBT), dibutyltin chloride(DBT) and tributyltin chloride(TBT) at the water‐surface microlayer (SM) interface were studied. The transport processes of the three compounds at the interface are very fast in the estuarine environment. The mass transfer coefficients are 1.54 m/h for MBT, 2.16 m/h for DBT, 1.56 m/h for TBT. The effect of various factors, including pH, salinity, suspended particulate and temperature, on the adsorptive behavior of TBT in the water's surface microlayer was also studied.     

Seven years from the first application of polyaluminium chloride in the Czech Republic – effects on phytoplankton communities in three water bodies

This study determines the efficiency of polyaluminium chloride application on phytoplankton species as a consequence of five reservoir restorations in the Czech Republic during the years 2005 and 2008, including the first ever large-scale application. Although polyaluminium chloride has been used in water treatment plants across the world, information about its application toward cyanobacterial blooms in nature is poor. Although the application of polyaluminium chloride did not cause any fundamental long-term changes in the composition of phytoplankton species or phosphorus load, instead causing fast and acute removal of the phytoplankton community, it may act as an algicidal compound with fast removal efficiency. All treated water bodies described in our study remained unaffected by cyanobacterial blooms and the hygienic limit for the purposes of recreation was not exceeded in any particular season. This article should serve as notice of the advantages and disadvantages of polyaluminium chloride application, and also warn against the uniform usage of this chemical as a method of reducing phytoplankton species in all types of water bodies where cyanobacteria are present. Moreover, data about the effects on non-target (invertebrates) species and microcystin release from cyanobacterial cells are also mentioned.     

Characterizing the vegetation community in the provenance slope with high-frequency debris flow北大核心CSCD

In order to explore the characteristics and species diversity of the vegetation growing in the provenance slope with high-frequency debris flow, we selected the slopes on the north and south sides of the valley in the Jiangjiagou watershed as the research object. The structural characteristics and quantitative compositions of the communities of vegetation growing on different positions of the slopes were investigated. The species composition, important value, species diversity, and ground and underground biomass of the different communities on the slope were statistically analyzed, and the correlations of the ground and underground biomass with the diversity were determined. The results showed that: of the total 49 species found, the herbs were the dominant flora, of which 33 were found on the northern slope and 23 were found on the southern slope. There were significant differences in the species composition and composition of the important values along the different positions on the slope, being mainly affected by the pioneer herbaceous plants. We found that Heteropogon contortus, Eulaliopsis binata, Arthraxon hispidus, and Sesbania cannabina were highly adaptable to debris flow. These four species are common to the area and can be used as the main configuration species for future ecological restoration. There were differences in the community characteristics and species diversity at different positions on the slope. For the southern slope of the valley, the Shannon-Wiener diversity index was in the order: stable zone (2.311) > instable zone (2.161) > deposit zone (2.036), and in the order: deposit zone (2.626) > stable zone (1.338) > instable zone (1.057) for the northern slope. There were significant differences in the biomass, being in the order: stable zone > instable zone > deposit zone, with higher values in the northern slope than in the southern slope. Based on the aforementioned results, we suggest that the restoration of vegetation in the area of the provenance slope having high-frequency debris flow should focus on the prevention and protection of the instable zone of the slope by natural processes of recovery. The deposit zone needs rational remediation measures. We should introduce local shrub and arbor to increase the species composition and promote the development of plant communities with vertical structures. © 2018 Science Press. All rights reserved.     

Simulations of the flow in the Mahakam river–lake–delta system,Indonesia

Large rivers often present a river–lake–delta system, with a wide range of temporal and spatial scales of the flow due to the combined effects of human activities and various natural factors, e.g., river discharge, tides, climatic variability, droughts, floods. Numerical models that allow for simulating the flow in these river–lake–delta systems are essential to study them and predict their evolution under the impact of various forcings. This is because they provide information that cannot be easily measured with sufficient temporal and spatial detail. In this study, we combine one-dimensional sectional-averaged (1D) and two-dimensional depth-averaged (2D) models, in the framework of the finite element model SLIM, to simulate the flow in the Mahakam river–lake–delta system (Indonesia). The 1D model representing the Mahakam River and four tributaries is coupled to the 2D unstructured mesh model implemented on the Mahakam Delta, the adjacent Makassar Strait, and three lakes in the central part of the river catchment. Using observations of water elevation at five stations, the bottom friction for river and tributaries, lakes, delta, and adjacent coastal zone is calibrated. Next, the model is validated using another period of observations of water elevation, flow velocity, and water discharge at various stations. Several criteria are implemented to assess the quality of the simulations, and a good agreement between simulations and observations is achieved in both calibration and validation stages. Different aspects of the flow, i.e., the division of water at two bifurcations in the delta, the effects of the lakes on the flow in the lower part of the system, the area of tidal propagation, are also quantified and discussed.     

Kelvin–Helmholtz instability in the presence of variable viscosity for mudflow resuspension in estuaries

The temporal stability of a parallel shear flow of miscible fluid layers of different density and viscosity is investigated through a linear stability analysis and direct numerical simulations. The geometry and rheology of this Newtonian fluid mixing can be viewed as a simplified model of the behavior of mudflow at the bottom of estuaries for suspension studies. In this study, focus is on the stability and transition to turbulence of an initially laminar configuration. A parametric analysis is performed by varying the values of three control parameters, namely the viscosity ratio, the Richardson and Reynolds numbers, in the case of initially identical thickness of the velocity, density and viscosity profiles. The range of parameters has been chosen so as to mimic a wide variety of real configurations. This study shows that the Kelvin–Helmholtz instability is controlled by the local Reynolds and Richardson numbers of the inflection point. In addition, at moderate Reynolds number, viscosity stratification has a strong influence on the onset of instability, the latter being enhanced at high viscosity ratio, while at high Reynolds number, the influence is less pronounced. In all cases, we show that the thickness of the mixing layer (and thus resuspension) is increased by high viscosity stratification, in particular during the non-linear development of the instability and especially pairing processes. This study suggests that mud viscosity has to be taken into account for resuspension parameterizations because of its impact on the inflection point Reynolds number and the viscosity ratio, which are key parameters for shear instabilities.     

Leading from the front? Social networks in navigating groups

In many group-living animals, leadership by only a fraction of the group members can be important for group navigation. It has been shown that subgroups of informed individuals can steer the remainder of the group without direct communication, resolving conflicts of interest through individual-to-individual interactions. We present a model for the navigation of collectively moving groups that includes preferential interactions between individuals as a way of imposing social network structures, known to be present in many species. We show that effective leadership can occur when leaders do not occupy frontal spatial positions and when navigation tendency is appropriately balanced with social position. Our model also shows that small minorities can dominate movement decisions if they have navigational knowledge combined with influential social network positions. Our findings highlight the mechanistic importance of social networks for the movement decisions of animal groups. We discuss the implications of our research for interpreting empirical observations.     

Can incomplete information lead to under-exploitation in the commons?

This paper analyzes the protection of a common pool resource (CPR) through the management of information. Specifically, we examine an entry deterrence model between an incumbent perfectly informed about the initial stock of a CPR and an uninformed potential entrant. In our model, the appropriation of the CPR by the incumbent reduces both players' future profits from exploiting the resource. In the case of complete information, we show that the incumbent operating in a high-stock common pool overexploits the CPR during the first period since it does not internalize the negative external effect that its first-period exploitation imposes on the entrant's future profits. This inefficiency, however, is absent when the commons totally regenerate across periods. Under incomplete information, we identify an additional form of inefficiency. In particular, the incumbent operating in a low-stock CPR underexploits the resource in order to signal the low available stock to potential entrants, deterring entry.