Species divergence and seasonal succession in rates of mate desertion in closely related Neotropical cichlid fishes

Across animal taxa, exclusive female offspring care has evolved repeatedly from biparental care, suggesting that the latter becomes evolutionarily unstable under certain conditions. Both the attributes of a species and the environment it experiences can help to predict shifts from one particular care mode to another. Nevertheless, factors inducing differences in care strategies among closely related species, or seasonal variation within species, have been subject to surprisingly little empirical testing. Here, we report the results of a field-based study that examined both among and within species variation in mate desertion in five species of closely related Nicaraguan cichlid fish in the genera Amphilophus and Amatitlania. The results show a link between female body size and male involvement in offspring care. Specifically, the larger the species the less often males were found to provide extended care. Furthermore, we found that solitary females became more common towards the end of the breeding season. We discuss the implications of this finding in the context of previous theoretical and empirical contributions regarding the frequency of offspring desertion by males.     

A probabilistic water quality index for river water quality assessment: a case study

Available water quality indices have some limitations such as incorporating a limited number of water quality variables and providing deterministic outputs. This paper presents a hybrid probabilistic water quality index by utilizing fuzzy inference systems (FIS), Bayesian networks (BNs), and probabilistic neural networks (PNNs). The outputs of two traditional water quality indices, namely the indices proposed by the National Sanitation Foundation and the Canadian Council of Ministers of the Environment, are selected as inputs of the FIS. The FIS is trained based on the opinions of several water quality experts. Then the trained FIS is used in a Monte Carlo analysis to provide the required input-output data for training both the BN and PNN. The trained BN and PNN can be used for probabilistic water quality assessment using water quality monitoring data. The efficiency and applicability of the proposed methodology is evaluated using water quality data obtained from water quality monitoring system of the Jajrood River in Iran.     

Survey on the pesticide residues in tea in south India

Tea is considered as a ‘health beverage’ due its antioxidant properties and resultant beneficial effects on human health. Such a beverage should be free from toxic elements such as pesticide residues and heavy metals. A large scale survey of teas produced in the tea factories of south India had been carried out for a period of three years from 2006 to 2008 and 912 tea samples were analysed for the residues of certain pesticides such as dicofol, ethion, quinalphos, hexaconazole, fenpropathrin, fenvalerate and propargite which are used for pest and disease control in tea in this part of the country. The analytical data proved that only less than 0.5 percentage of tea samples had residues of these pesticides. However, residues of pesticides were below their maximum limits in tea, stipulated by the European Union, Codex Alimentarius Commission of FAO/WHO and Prevention of Food Adulteration Act of Govt. of India.     

Prevalence of heavy metal resistance in bacteria isolated from tannery effluents and affected soil

In the present study, a total of 198 bacteria were isolated, 88 from the tannery effluents and 110 from agricultural soil irrigated with the tannery effluents. Tannery effluents and soils were analyzed for metal concentrations by atomic absorption spectrophotometer. The tannery effluents and soil samples were found to be contaminated with chromium, nickel, zinc, copper, and cadmium. All isolates were tested for their resistance against Cr^6?+?, Cr^3?+?, Ni^2?+?, Zn^2?+?, Cu^2?+?, Cd^2?+?, and Hg^2?+?. From the total of 198 isolates, maximum bacterial isolates were found to be resistant to Cr^6?+? 178 (89.9%) followed by Cr^3?+? 146 (73.7%), Cd^2?+? 86 (43.4%), Zn^2?+? 83 (41.9%), Ni^2?+? 61 (30.8%), and Cu^2?+? 51 (25.6%). However, most of the isolates were sensitive to Hg^2?+?. Among the isolates from tannery effluents, 97.8% were resistant to Cr^6?+? and 64.8% were resistant to Cr^3?+?. Most of the soil isolates were resistant against Cr^6?+? (83.6%) and Cr^3?+? (81.8%). All isolates were categorized into Gram-positive and Gram-negative bacteria. In a total of 114 Gram-positive isolates, 91.2% were resistant to Cr^6?+? followed by 73.7% to Cr^3?+?, 42.1% to Zn^2?+?, 40.4% to Cd^2?+?, and 32.5% to Ni^2?+?. Among Gram-negative isolates, 88.1% were found showing resistance to Cr^6?+?, 75.0% to Cr^3?+?, and 47.6% were resistant to Cd^2?+?. Majority of these metal-resistant isolates were surprisingly found sensitive to the ten commonly used antibiotics. Out of 198 isolates, 114 were found sensitive to all antibiotics whereas only two isolates were resistant to maximum eight antibiotics at a time. Forty-one and 40 isolates which constitute 20.7% and 20.2% were resistant to methicilin and amoxicillin, respectively.     

Drinking water quality assessment in Southern Sindh (Pakistan)

The southern Sindh province of Pakistan adjoins the Arabian Sea coast where drinking water quality is deteriorating due to dumping of industrial and urban waste and use of agrochemicals and yet has limited fresh water resources. The study assessed the drinking water quality of canal, shallow pumps, dug wells, and water supply schemes from the administrative districts of Thatta, Badin, and Thar by measuring physical, chemical, and biological (total coliform) quality parameters. All four water bodies (dug wells, shallow pumps canal water, and water supply schemes) exceeded WHO MPL for turbidity (24%, 28%, 96%, 69%), coliform (96%, 77%, 92%, 81%), and electrical conductivity (100%, 99%, 44%, 63%), respectively. However, the turbidity was lower in underground water, i.e., 24% and 28% in dug wells and shallow pumps as compared to open water, i.e., 96% and 69% in canal and water supply schemes, respectively. In dug wells and shallow pumps, limits for TDS, alkalinity, hardness, and sodium exceeded, respectively, by 63% and 33%; 59% and 70%, 40% and 27%, and 78% and 26%. Sodium was major problem in dug wells and shallow pumps of district Thar and considerable percent in shallow pumps of Badin. Iron was major problem in all water bodies of district Badin ranging from 50% to 69% and to some extent in open waters of Thatta. Other parameters as pH, copper, manganese, zinc, and phosphorus were within standard permissible limits of World Health Organization. Some common diseases found in the study area were gastroenteritis, diarrhea and vomiting, kidney, and skin problems.     

Modelling the long-term morphological evolution of the Clyde Estuary,Scotland, UK

The long-term morphodynamic response of the Clyde Estuary to any possible change in environmental forcing associated with global climate change and human interference is examined here using a model based on a systems approach. The model, which uses Boolean Algebra as its formal mathematical language, provides a qualitative insight into the long term morphodynamic behaviour of the estuarine system, at this level without the need for detailed and quantitative hydrodynamic and morphodynamic process knowledge or extensive data resources. The model predictions suggest that the long-term morphological changes in the Clyde Estuary largely depend on the fluvial flow of the River Clyde. Salt marshes in the upper reaches of the estuary were found to be the most vulnerable morphological feature of the estuary. In the event of increased river flow in the future, a likely situation according to climate change scenarios, saltmarshes will deplete or disappear altogether, irrespective of the sediment influx into the estuary. Changes to waves and tides will also contribute to the evolution by taking the estuary through significantly different intermediate morphological states whilst evolving towards a stable end state.     

Near-critical free-surface flows: real fluid flow analysis

An open channel flow with a flow depth close to the critical depth is characterised by a curvilinear streamline flow field that results in steady free surface undulations. Near critical flows of practical relevance encompass the undular hydraulic jump when the flow changes from supercritical (F > 1) to subcritical (F < 1), and the undular weir flow over broad-crested weirs where the flow changes from subcritical (F < 1) to supercritical (F > 1). So far these flows were mainly studied based on ideal fluid flow computations, for which the flow is assumed irrotational and, thus, shear forces are absent. While the approach is accurate for critical flow conditions (F = 1) in weir and flumes, near-critical flows involve long distances reaches, and the effect of friction on the flow properties cannot be neglected. In the present study the characteristics of near-critical free-surface flows are reanalysed based on a model accounting for both the streamline curvature and friction effects. Based on the improved model, some better agreement with experimental results is found, thereby highlighting the main frictional features of the flow profiles.     

Predator–prey models: an application for the plankton dynamics of lake Geneva

In this paper we present a hierarchical Bayesian analysis for a predator–prey model applied to ecology considering the use of Markov Chain Monte Carlo methods. We consider the introduction of a random effect in the model and the presence of a covariate vector. An application to ecology is considered using a data set related to the plankton dynamics of lake Geneva for the year 1990. We also discuss some aspects of discrimination of the proposed models.     

Confronting Management Challenges in Highly Uncertain Natural Resource Systems: a Robustness–Vulnerability Trade-off Approach

This paper presents a framework for the study of policy implementation in highly uncertain natural resource systems in which uncertainty cannot be characterized by probability distributions. We apply the framework to parametric uncertainty in the traditional Gordon–Schaefer model of a fishery to illustrate how performance can be sacrificed (traded-off) for reduced sensitivity and hence increased robustness, with respect to model parameter uncertainty. With sufficient data, our robustness–vulnerability analysis provides tools to discuss policy options. When less data are available, it can be used to inform the early stages of a learning process. Several key insights emerge from this analysis: (1) the classic optimal control policy can be very sensitive to parametric uncertainty, (2) even mild robustness properties are difficult to achieve for the simple Gordon–Schaefer model, and (3) achieving increased robustness with respect to some parameters (e.g., biological parameters) necessarily results in increased sensitivity (decreased robustness) with respect to other parameters (e.g., economic parameters). We thus illustrate fundamental robustness–vulnerability trade-offs and the limits to robust natural resource management. Finally, we use the framework to explore the effects of infrequent sampling and delays on policy performance.