Sediment delivery linkages in a chaparral watershed following a wildfire

The purpose of this research is to study the temporal and spatial sediment delivery to and within the stream network following a wildfire on a chaparral watershed in Arizona, USA. Methods include interpretation of channel processes (aggradation, degradation) from sequential aerial photographs, field measurements of sediment delivery, and overland flow from ten microwatersheds having different vegetation cover (no vegetation, chaparral cover, and bare with vegetation buffer strips). The response of the watershed to the fire was very complex. The fire reduced the chaparral cover to zero in most locations and severe erosion led to filling of the channels by sediment. With vegetation recovery, sediment delivery from the watershed practically ceased. Vegetation buffer strips were mainly responsible for arresting the sediment delivered from bare hillslopes. Relatively clear water, entering the channels, caused degradation in the tributaries that delivered the sediment into the main stream at El Oso Creek. Due to high water infiltration by immense volumes of sediment deposits in the middle reach, the sediment from the tributaries was deposited as in-channel fans. In contrast, the upper reach of El Oso Creek behaved similarly to the tributaries. It aggraded after the fire and was followed by degradation. The low reach of El Oso Creek is degrading because it is still adjusting base level to the incision of the master stream. Implications of this study are that land managers, concerned to avoid severe erosion and sedimentation following disturbance, should concentrate on the establishment and enhancement of vegetation buffer strips along channel banks.     

Assigning money amounts to represent intrinsic value of precious eco-systems in developing countries

Conclusion  The need is urgent, if the ongoing rapid degradation of the remaining precious eco-systems of the developing countries are to be put under control while there is still time, for developing a procedure by which the real world intrinsic meaningfulness to people of precious eco-systems is recognized by assigning them monetary values to be considered in benefit/cost analyses. The procedures recommended by the U.S. Corps of Engineers and Resources of the Future for use in the USA seem to be much too complex for application in developing countries in the foreseeable future. Rather a very pragmatic approach is recommended based on actual experience in money outlays for such protection in USA projects, with the amounts modified to suit developing country conditions. Hopefully the IAAs (Multilateral Development Banks, Bilaterials, U.N. Agencies) will carry out the recommended R&D studies to produce a prescribed methodology recognized by economic, environmental, and political decision makers of both the IAAs and the DCs to be appropriate for use in planning and evaluating DC projects.     

Primate home-range size and metabolic needs

Summary We test the hypothesis that cross-species variation in home range size across primates is determined by the metabolic needs of the animals occupying the home range and by their diet. Metabolic needs are calculated from published records of group structure, time spent in different activities and the metabolic costs of those activities. Data from 20 species demonstrate clear relationships between home range, diet and metabolic needs. Although correlations are in the expected directions, simple models relating diet to home range size and metabolic needs do not predict the functional relationships found. This may be because the data are inadequate or because the models are wrong. An empirical relationship between relative home-range size and diet distinguishes between the arboreal and terrestrial species in the sample.     

Minor illness as a legitimate reason for absence

This study proposes that the perceived legitimacy of minor illness as a reason for absence varies according to the nature of the illness, sex, job grade/socio‐economic status and age. A measure of perceived legitimacy was constructed which incorporated illnesses commonly given as reasons for short‐term absence. Thirteen hundred civil servants provided data on an employee survey. Absence frequency data were collected for 115 of these respondents over a 55‐month period. General support was found for four of the five study hypotheses. Contrary to one hypothesis, it was found that men legitimize minor illnesses as reasons for absence more than women. Clusters of minor illnesses were identified using a factor analysis. The implications for management responses to absence and for further research into the perception of minor illness are considered. Copyright © 1999 John Wiley & Sons, Ltd.     

Sterol production and phytosterol bioconversion in two species of heterotrophic protists, Oxyrrhis marina and Gyrodinium dominans

The kinetics and efficiency of sterol production and bioconversion of phytosterols in two heterotrophic protists Oxyrrhis marina and Gyrodinium dominans were examined by feeding them two different algal species (Rhodomonas salina and Dunaliella tertiolecta) differing in sterol profiles. R. salina contains predominantly brassicasterol (?99%) and <2% cholesterol. The major sterols in D. tertiolecta are ergosterol (45–49%), 7-dehydroporiferasterol (29–31%) and fungisterol (21–26%). O. marina fed R. salina metabolized dietary brassicasterol to produce 22-dehydrocholesterol and cholesterol. O. marina fed D. tertiolecta metabolized dietary sterols to produce cholesterol, 22-dehydrocholesterol, brassicasterol and stigmasterol. G. dominans fed either R. salina or D. tertiolecta metabolized dietary sterols to make cholesterol, brassicasterol and a series of unknown sterols. When protists were fed R. salina, which contains cholesterol, the levels of cholesterol were increased to a magnitude of nearly 5- to 30-fold at the phytoplankton-heterotrophic protist interface, equivalent to a production of 172.5 ± 16.2 and 987.7 ± 377.7 ng cholesterol per mg R. salina carbon consumed by O. marina and G. dominans, respectively. When protists were fed D. tertiolecta, which contains no cholesterol, a net production of cholesterol by the protists ranged from 123.2 ± 30.6 to 871.8 ± 130.8 ng per mg algal C consumed. Cholesterol is not only the dominant sterol, but a critical precursor for many physiologically functional biochemicals in higher animal. As intermediates, these heterotrophic protists increase the amount of cholesterol at the phytoplankton–zooplankton interface available to higher trophic levels relative to zooplankton feeding on algae directly.     

Genus-specific associations of marine sponges with group I crenarchaeotes

Sponges have rich and diverse associated microbial communities, which may have important functions in their metabolism. A survey of the archaeal communities of 23 poriferan species, focusing on the family Axinellidae, was conducted over the period 2002–2004 using 16S rDNA gene libraries created with archaeal-specific primers. The 28S rDNA sequences of the sponge hosts were also obtained. Of 23 species, 19 showed evidence of archaeal communities from group C1a (marine group I; Crenarchaeota), with three of these also showing evidence of Archaea from group E2 (marine group II; Euryarchaeota). Within the Crenarchaeota, two strongly supported sponge-specific clades were identified corresponding to the sponge family Axinellidae, and a novel sponge clade denoted clade C. These findings suggest that these archaea have evolved closely with their sponge hosts and are likely to play an important role in their metabolism.

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Comparative lipid dynamics of euphausiids from the Antarctic and Northeast Pacific Oceans

To better understand the feeding and reproductive ecology of euphausiids (krill) in different ocean environments, lipid classes and individual lipid components of four different species of euphausiids from Northeast Pacific (temperate species) and Southern Ocean (Antarctic species) were analyzed in animals from multiple life stages and seasons. The dominant krill species in the Northeast Pacific Euphausia pacifica and Thysanoessa spinifera, were compared to the two major Antarctic species, Euphausia superba and E. crystallorophias. Analysis comprised total lipid and lipid classes together with individual fatty acid and sterol composition in adults, juveniles, and larvae. Antarctic krill had much higher lipid content than their temperate relatives (10–50 and 5–20% of dry mass for Antarctic and temperate species, respectively) with significant seasonal variations observed. Phospholipids were the dominant lipid class in both temperate krill species, while neutral storage lipids (wax esters and triacylglycerols for E. crystallorophias and E. superba, respectively) were the major lipid class in Antarctic krill and accounted for up to 40% of the total lipid content. Important fatty acids, specifically 16:0, 18:1ω9, 20:5ω3, and 22:6ω3, were detected in all four krill species, with minor differences between species and seasons. Detailed lipid profiles suggest that krill alter their lipid composition with life stage and season. In particular, larval Antarctic krill appear to utilize alternate food resources (i.e., sea-ice associated organisms) during austral winter in contrast to juveniles and adults (i.e., seston and copepods). Lipid dynamics in krill among krill in both systems appear closely linked to their life cycle and environmental conditions including food availability, and can provide a more complete comparative ecology of euphausiids in these environmentally distinct systems.     

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.     

Photochemical Conversion of NO to NO2 by Hydrocarbons in an Outdoor Chamber

Significant differences occur between results of chamber work conducted outdoors versus work conducted indoors under constant light intensity. Under outdoor conditions at constant [NO_X]_O, lower [HC]o resulted in lower [NO₂]_max and NO₂ dosage during the daylight hours. The percent reduction in [NO₂]_max was a function of the [HC]₀ reduction and the [NO_X]_O level. Under all experimental conditions the 10 hour N0₂ average to maximum N0₂ concentration ratio appeared to be constant at 0.73 during the daylight hours. A regression equation relating [NO_x]_max to [NO_X]_O, [HC]_O, and measures of solar radiation accounted for 92% of the variance in the data. Although there is unavoidable confoundment between [HC]₀ and solar radiation, the HC term in this regression equation can introduce ±20 % change in [N0₂]_max - This variation can be partially offset or enhanced by variations in solar radiation.