Environmental indicators as tools for the management of estuaries—Methodology and case study of the Tejo estuary

The need for a better management of estuaries requires an environmental characterization following a methodology that allows the comparison of distinct estuarine systems and the assessment of their evolution. The peculiar characteristics of estuaries, in particular their intrinsic variability, make this characterization difficult and there is no commonly accepted general methodology available. The approach followed in freshwater ecosystems is generally based on the concept of environmental indicators, but such a concept has not been developed for estuaries. Indeed, a different approach is needed here, due to the spatial heterogeneity and the different time scales associated with the processes that control water quality. This paper presents a proposal for a methodology that starts with observed values and uses a procedure to integrate these values in time and space in order to calculatesignificant values, upon whichnormalized indicators are built which take into account criteria based either on legal, scientific or heuristic concentration limits. A normalization is carried out in two steps: (1) application of a mathematical operator to theignificant values, (2) transformation using the concept ofpenalty curves. This methodology may be complemented with the definition ofquality classes, particularly appealing and useful, as tools to communicate with decision makers and the public in general. Water quality data pertaining to the Tejo estuary are used to test the methodology.     

A method to quantify the regularity of barred plumage patterns

Barred plumage is common among bird species. It is often interpreted as a form of crypsis because pigmentation patterns are less detectable against heterogeneous backgrounds. However, it has also been suggested that barred plumage could signal plumage condition, because it makes irregularities in the plumage perceptually salient. Little empirical work exists on the function of barred plumage, in part because we lack a way for quantifying the regularity of the pattern. Here, we present a method to analyze digital photographs of barred plumage and quantify the regularity of its pattern, and also provide software to perform the analysis. Using museum skins of five avian species, we tested under which conditions the method reliably captures differences among conspecific males in the regularity of their barred pattern. We found that measurements of regularity were highly repeatable when lighting conditions were standardized, unlike under variable illumination, and a relatively large area of barred plumage was analyzed, rather than small and non-representative subsections of plumage. The range of conditions under which the method performs well makes it adequate for use in the field, and we hope that it fosters research on the function of barred plumage as a communication signal.     

Ethical Frameworks and Farmer Participation in Controversial Farming Practices

There are a number of agricultural farming practices that are controversial. These may include using chemical fertilizers, pesticides, and herbicides, and planting genetically modified crops, as well as the decision to dehorn cattle rather than raise polled cattle breeds. We use data from a survey of Missouri crop and livestock producers to determine whether a farmer’s ethical framework affects his or her decision to engage in these practices. We find that a plurality of farmers prefer an agricultural policy that reflects principles based on rights rather than principles of utilitarianism or justice. Furthermore, after controlling for personal and farm characteristics, we find a positive correlation between farmers preferring a rights-based policy and a farmer’s use of chemical farm inputs and polled rather than horned cattle. We also find that a combination of ethical framework and farm and farmer characteristics correlate with decisions to use farm chemicals, while only farm and farmer characteristics affect the decision to plant GM crops and only a farmer’s ethical framework affects the decision to use polled cattle.     

A preconcentration procedure for the determination of cadmium in biological material after on-line cloud point extraction

In this paper, a method involving on-line preconcentration with cloud point extraction for the determination of cadmium in biological samples is presented. The procedure is based on the sorption of micelles containing Cd(II) ions and the reagent 4-(5'-bromo-2'-thiazolylazo)orcinol (Br-TAO) in a minicolumn packed with polyester. The surfactant Triton X-114 was used in the formation of micelles. After sorption, the Cd(II) ions were desorbed from the minicolumn with acid eluent and determined by flame atomic absorption spectrometry. Parameters influencing the cloud point extraction were studied. The method showed a detection limit of 0.5 μg l(-1) and an enhancement factor of 27. The accuracy was tested by determination of cadmium in certified reference materials (spinach leaves 1570a and tomato leaves 1573a) from the National Institute of Standards and Technology.     

Constructing a policy and institutional framework for an ecosystem-based approach to managing the Lower Amazon floodplain

A regional experiment in co-management is underway in the Lower Amazon that is developing the basic policy and institutional elements for an ecosystem-based approach to floodplain management. This initiative grew out of the grassroots movement of floodplain communities who, concerned with excessive commercial fishing pressure on local fisheries, took control of local lakes and implemented collective agreements regulating fishing activity. This paper describes the main elements of the evolving regional management system. This process has focused on four main dimensions of floodplain settlement and resource use: development of sustainable management systems for floodplain resources, policies and institutions for fisheries co-management, collective agreements for grazing cattle on floodplain grasslands, and a land tenure policy consistent with the objectives of the evolving co-management system. Over the last year INCRA, the National Institute for Colonization and Agrarian Reform, has begun implementation of a comprehensive new land tenure policy that could resolve structural deficiencies in the existing co-management system and provide the basis for the ecosystem-based management of the Lower Amazon floodplain. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Female and male serins (Serinus serinus) respond differently to derived song traits

We tested if male or female behavior towards manipulated song indicates intra- or inter-sexual selection of two characteristics of serin song that are extreme and evolutionarily derived in this species: high frequency and fast syllable rate. In a first experiment, we monitored vocal responses and attendance to song playbacks. Female behavior indicated a preference for high-frequency song and suggested an aggressive function for fast syllable rates, as fast songs inhibited vocal response. Males did not show discrimination of frequency or syllable rate with this experimental design. The second experiment used a simple approach/no approach design, and in this experiment, males showed stronger discrimination between stimuli than did females. Therefore, sex differences in discrimination appear not to result from differences in perceptual abilities but from differences in the context of stimulus presentation. The second experiment also supported a role of song frequency in female choice, as the effect of frequency was limited to females: males did not respond differently to song frequency and approached high-frequency songs less than females did. Results of this experiment also supported an aggressive function for fast syllable rates, as the effect of fast songs did extend to male behavior. Taken together, our results indicate that the high frequency and fast syllable rate of serin song cannot result from a single selection process: while high frequency may have evolved by inter-sexual selection, syllable rate provokes a pattern of response that is more consistent with intra-sexual selection.     

Vegetation productivity under climate change depends on landscape complexity in tropical drylands

Mitigation and Adaptation Strategies for Global Change - All Clean Development Mechanism (CDM) projects are designed to contribute to the sustainable development of the host country. Livelihood is...     

Federalism,water, and (de)centralization in Brazil: the case of the São Francisco River water diversion

Regional Environmental Change - The Brazilian Northeastern semi-arid region’s history has been characterized by drought, water scarcity, and poor living conditions. For the last...