Benthic metabolism as an indicator of stream ecosystem health

We tested direct and indirect measures of benthic metabolism as indicators of stream ecosystem health across a known agricultural land-use disturbance gradient in southeast Queensland, Australia. Gross primary production (GPP) and respiration (R-24) in benthic chambers in cobble and sediment habitats, algal biomass (as chlorophyll a) from cobbles and sediment cores, algal biomass accrual on artificial substrates and stable carbon isotope ratios of aquatic plants and benthic sediments were measured at 53 stream sites, ranging from undisturbed subtropical rainforest to catchments where improved pasture and intensive cropping are major land-uses. Rates of benthic GPP and R-24 varied by more than two orders of magnitude across the study gradient. Generalised linear regression modelling explained 80% or more of the variation in these two indicators when sediment and cobble substrate dominated sites were considered separately, and both catchment and reach scale descriptors of the disturbance gradient were important in explaining this variation. Model fits were poor for net daily benthic metabolism (NDM) and production to respiration ratio (P/R). Algal biomass accrual on artificial substrate and stable carbon isotope ratios of aquatic plants and benthic sediment were the best of the indirect indicators, with regression model R-2 values of 50% or greater. Model fits were poor for algal biomass on natural substrates for cobble sites and all sites. None of these indirect measures of benthic metabolism was a good surrogate for measured GPP. Direct measures of benthic metabolism, GPP and R-24, and several indirect measures were good indicators of stream ecosystem health and are recommended in assessing process-related responses to riparian and catchment land use change and the success of ecosystem rehabilitation actions.

Increased risk of psychosis in rural-born individuals: An Australian catchment-area study

The aim of the Brisbane Psychosis Study was to examine a range of candidate genetic and nongenetic risk factors in a large, representative sample of patients with psychosis and well controls. The patients (n=310) were drawn from a census conducted as part of the National Survey of Mental Health and Wellbeing. An age and sex-matched well control group (n = 303) was drawn from the same catchment area. Candidate risk factors assessed included migrant status of proband and proband's parents, occupation of father at time of proband's birth, place of birth and place of residence during the first 5 years of life (urbanicity), self-reported pregnancy and birth complications, season of birth and family history. The main analyses were group (cases versus controls) comparisons, with planned subgroup analyses (1) group comparisons for Australian-born subjects only, (2) within-patient comparisons of affective versus nonaffective psychoses. Of the individuals with psychosis, 68% had DSMIII-R schizophrenia. In the main analyses, there were no significant group differences on season of birth, place of birth, place of residency in the first 5 years, occupation of fathers at time of birth or pregnancy and birth complications. Patients had significantly more family members with schizophrenia. Significantly fewer of the patients were migrants or offspring of migrants compared to the controls. When only Australianborn subjects were assessed (n=457), the findings were essentially unchanged apart from a significant excess of cases born in rural sites (chi-square=9.54, df3, p=0.02). There were no significant differences in the risk factors for the comparison involving affective versus nonaffective psychoses. Potential explanations for the inverse urban-rural risk gradient are reviewed. The Stanley Foundation supported this project

Empirical catchment-wide rainfall erosivity models for two rivers in the humid tropics of Australia

The concept of rainfall erosivity is extended to the estimation of catchment sediment yield and its variation over time. Five different formulations of rainfall erosivity indices, using annual, monthly and daily rainfall data, are proposed and tested on two catchments in the humid tropics of Australia. Rainfall erosivity indices, using simple power functions of annual and daily rainfall amounts, were found to be adequate in describing the interannual and seasonal variation of catchment sediment yield. The parameter values of these rainfall erosivity indices for catchment sediment yield are broadly similar to those for rainfall erosivity models in relation to the R-factor in the Universal Soil Loss Equation.

Severity of hypertension in familial hyperaldosteronism type I: Relationship to gender and degree of biochemical disturbance

In familial hyperaldosteronism type I (FH-I), inheritance of a hybrid 11 beta-hydroxylase/aldosterone synthase gene causes ACTH-regulated aldosterone overproduction. In an attempt to understand the marked variability in hypertension severity in FH-I, we compared clinical and biochemical characteristics of 9 affected individuals with mild hypertension (normotensive or onset of hypertension after 15 yr, blood pressure never >160/100 mm Hg, less than or equal to 1 medication required to control hypertension, no history of stroke, age >18 yr when studied) with those of 17 subjects with severe hypertension (onset before 15 yr, or systolic blood pressure >180 mm Hg or diastolic blood pressure >120 mm Hg at least once, or greater than or equal to 2 medications, or history of stroke). Severe hypertension was more frequent in males (11 of 13 males vs. 6 of 13 females; P

Finger and A-B ridge count, and fluctuating asymmetry in psychosis: A catchment area case-control study

Dermatoglyphic measures are of interest to schizophrenia research because they serve as persistent markers of deviant development in foetal life. Several studies have reported alterations in A–B ridge counts, total finger ridge counts and measures related to asymmetry in schizophrenia. The aim of this study was to assess these measures in an Australian catchment area, case-control study. Individuals with psychosisŽns246.were drawn from a catchment-area prevalence study, and well controlsŽns229. were recruited from the same area. Finger and palm prints were taken usingan inkless technique and all dermatoglyphic measures were assessed by a trained rater blind to case status. The dermatoglyphic measures Žfinger ridge count, A–B ridge count, and their derived asymmetry measures. were divided into quartiles based on the distribution of these variables in controls. The main analysis Žlogistic regression controlled for age and sex.examined all psychotic disorders, with planned subgroup analyses comparing controls with Ž1. nonaffective psychosis Žschizophrenia, delusional disorder, schizophreniform psychosis, atypical psychosis.andŽ2. affective psychosis Ždepression with psychosis, bipolar disorder, schizoaffective psychosis.. There were no statistically significant alterations in the odds of havinga psychotic disorder for any of the dermatoglyphic measures. The results did not change when we examined affective and nonaffective psychosis separately. The dermatoglyphic features that distinguish schizophreniar psychosis in other studies were not identified in this Australian study. Regional variations in these findings may provide clues to differential ethnicrgenetic and environmental factors that are associated with schizophrenia. The Stanley Foundation supported this project.

Regional investment strategies (RIS) and coastal catchment initiative (CCI) project alignmnet to Great Barrier Reef Water Quality Protection Plan

The Great Barrier Reef Water Quality Protection Plan (the Reef Plan) is a joint initiative of the Australian and Queensland Governments. The Reef Plan aims to progress an integrated approach to natural resource management planning by building on the existing partnerships between the different levels of government, industry groups, the community and research providers within the Reef catchments, principally through partnerships with the regional natural resource management (NRM) bodies.

A small disturbance in the strong vortex flow

A small disturbance in the axisymmetric, bathtub-like flow with strong vorticity is considered and the asymptotic representation of the solution is found. It is shown that if the disturbance is smaller than a certain critical scale, the conventional strong vortex approximation cannot describe the field generated by the disturbance not only in the vicinity of the disturbance but also at the distances much larger than the critical scale. (C) 2001 American Institute of Physics.

A decision support process to compare Riparian revegetation options in Scheu Creek catchment in North Queensland

While riparian vegetation can play a major role in protecting land, water and natural habitat in catchments, there are high costs associated with tree planting and establishment and in diverting land from cropping. The distribution of costs and benefits of riparian revegetation creates conflicts in the objectives of various stakeholder groups. Multicriteria analysis provides an appropriate tool to evaluate alternative riparian revegetation options, and to accommodate the conflicting views of various stakeholder groups. This paper discusses an application of multicriteria analysis in an evaluation of riparian revegetation policy options for Scheu Creek, a small sub-catchment in the Johnstone River catchment in north Queensland, Australia. Clear differences are found in the rankings of revegetation options for different stakeholder groups with respect to environmental, social and economic impacts. Implementation of a revegetation option will involve considerable cost for landholders for the benefits of society. Queensland legislation does not provide a means to require farmers to implement riparian revegetation, hence the need for subsidies, tau incentives and moral suasion. (C) 2001 Academic Press.

A theoretical exploration of catchment-scale sediment delivery

This paper proposes a theoretical explanation of the variations of the sediment delivery ratio (SDR) versus catchment area relationships and the complex patterns in the behavior of sediment transfer processes at catchment scale. Taking into account the effects of erosion source types, deposition, and hydrological controls, we propose a simple conceptual model that consists of two linear stores arranged in series: a hillslope store that addresses transport to the nearest streams and a channel store that addresses sediment routing in the channel network. The model identifies four dimensionless scaling factors, which enable us to analyze a variety of effects on SDR estimation, including (1) interacting processes of erosion sources and deposition, (2) different temporal averaging windows, and (3) catchment runoff response. We show that the interactions between storm duration and hillslope/channel travel times are the major controls of peak-value-based sediment delivery and its spatial variations. The interplay between depositional timescales and the travel/residence times determines the spatial variations of total-volume-based SDR. In practical terms this parsimonious, minimal complexity model could provide a sound physical basis for diagnosing catchment to catchment variability of sediment transport if the proposed scaling factors can be quantified using climatic and catchment properties.

Genotoxicity of inorganic lead salts and disturbance of microtubule function

Lead compounds are known genotoxicants, principally affecting the integrity of chromosomes. Lead chloride and lead acetate induced concentration-dependent increases in micronucleus frequency in V79 cells, starting at 1.1 μ M lead chloride and 0.05 μ M lead acetate. The difference between the lead salts, which was expected based on their relative abilities to form complex acetato-cations, was confirmed in an independent experiment. CREST analyses of the micronuclei verified that lead chloride and acetate were predominantly aneugenic (CREST-positive response), which was consistent with the morphology of the micronuclei (larger micronuclei, compared with micronuclei induced by a clastogenic mechanism). The effects of high concentrations of lead salts on the microtubule network of V79 cells were also examined using immunofluorescence staining. The dose effects of these responses were consistent with the cytotoxicity of lead(II), as visualized in the neutral-red uptake assay. In a cell-free system, 20-60 μ M lead salts inhibited tubulin assembly dose-dependently. The no-observed-effect concentration of lead(II) in this assay was 10 μ M. This inhibitory effect was interpreted as a shift of the assembly/disassembly steady-state toward disassembly, e.g., by reducing the concentration of assembly-competent tubulin dimers. The effects of lead salts on microtubule-associated motor-protein functions were studied using a kinesin-gliding assay that mimics intracellular transport processes in vitro by quantifying the movement of paclitaxel-stabilized microtubules across a kinesin-coated glass surface. There was a dose-dependent effect of lead nitrate on microtubule motility. Lead nitrate affected the gliding velocities of microtubules starting at concentrations above 10 μ M and reached half-maximal inhibition of motility at about 50 μ M. The processes reported here point to relevant interactions of lead with tubulin and kinesin at low dose levels. Environ. Mal. Mutagen. 45:346-353, 2005. © 2005 Wiley-Liss, Inc.