An assessment of the impacts of timber plantations on water quality and biodiversity values of Marbellup Brook, Western Australia

Despite the fact that the establishment and maintenance of blue gum plantations can potentially result in the removal of riparian vegetation, the presence of increased levels of sediments, pesticides, and nutrients, and consequently, the loss of in-stream biodiversity, few studies exist that have looked at the impacts of timber plantations on in-stream biota. The goals of this study were thus to determine water quality, riparian condition, and in-stream biodiversity values of local streams draining blue gum plantations in the Marbellup Brook catchment in Western Australia and to compare these values with those of streams associated with other land uses. Selected water quality and habitat variables and in-stream macroinvertebrate biodiversity were measured in 2006 and 2007 at 28 sites falling into five broad categories based on the predominant land use within 200 m of each study reach. Overall, the results indicated that ??blue gum plantation?? sites often had better water quality, riparian condition, and biodiversity values than ??pasture unfenced,?? and sometimes ??pasture fenced?? sites, but water quality and biodiversity values at these sites were not as good as those associated with ??remnant?? native vegetation sites. The location of the blue gum plantation sites along the disturbance gradient investigated was attributed to both present management and past land uses in the subcatchments investigated. As this study was conducted at a time when blue gum plantations were in an on-growing phase, it was recommended that future research on the impact of blue gum plantations on waterways in southwestern Australia should include an investigation of the impacts of timber clear-cutting and extraction. Longer-term cumulative and downstream effects of blue gum plantations on local waterways also need to be investigated.     

Towards the development of a multidisciplinary understanding of the effects of toxic chemical mixtures on health

Mixtures can be divided into simple (chemicals with comparable properties—health risk assessments on the chemicals) and complex, which can be further subdivided into defined (a reasonably distinct composition, created at a specific time and place despite dissimilar components—risk assessments on the common source) and coincidental (chemicals without similar properties or constant composition in time or space—risk assessments on the receptor). Interactions recognized are: independent action, dose addition (additivity), and potentiation (synergy and antagonism). Unpredicted outcomes need recognition. New approaches in higher education and multidisciplinary investigations are essential. The community of the Society for Environmental Geochemistry and Health should help clarify points such as when transformations in mixtures may become important enough to alter the classification and the risk assessment. The multidisciplinary community is also well placed to support the integration of nonchemical influences into mixture analysis and to contribute to the investigation of cumulative and multiple exposures.     

INFLUENCES OF WATERSHED,RIPARIAN‐CORRIDOR,AND REACH‐SCALE CHARACTERISTICS ON AQUATIC BIOTA IN AGRICULTURAL WATERSHEDS1

ABSTRACT: Multivariate analyses and correlations revealed strong relations between watershed and riparian‐corridor land cover, and reach‐scale habitat versus fish and macroinvertebrate assemblages in 38 warmwater streams in eastern Wisconsin. Watersheds were dominated by agricultural use, and ranged in size from 9 to 71 km² Watershed land cover was summarized from satellite‐derived data for the area outside a 30‐m buffer. Riparian land cover was interpreted from digital orthophotos within 10‐, 10‐to 20‐, and 20‐to 30‐m buffers. Reach‐scale habitat, fish, and macroinvertebrates were collected in 1998 and biotic indices calculated. Correlations between land cover, habitat, and stream‐quality indicators revealed significant relations at the watershed, riparian‐corridor, and reach scales. At the watershed scale, fish diversity, intolerant fish and EPT species increased, and Hilsenhoff biotic index (HBI) decreased as percent forest increased. At the riparian‐corridor scale, EPT species decreased and HBI increased as riparian vegetation became more fragmented. For the reach, EPT species decreased with embeddedness. Multivariate analyses further indicated that riparian (percent agriculture, grassland, urban and forest, and fragmentation of vegetation), watershed (percent forest) and reach‐scale characteristics (embeddedness) were the most important variables influencing fish (IBI, density, diversity, number, and percent tolerant and insectivorous species) and macroinvertebrate (HBI and EPT) communities.     

Nutrient accumulation in trees and soil following irrigation with municipal effluent in Australia

Irrigation of tree crops is being evaluated as a method of land disposal of municipal effluent in Australia. A study was carried out from 1980-84 in which seven tree species were sprinkler-irrigated with effluent at an annual rate of 1191-1752 mm. Effective weed control and frequent irrigation resulted in good survival of all species (range 83-100%) at 12 months. Total productivity was estimated at age 4 years by measuring biomass of each species inclusive of litter and roots to a soil depth of 80 cm. Biomass production of the high-yielding species, flooded gum (Eucalyptus grandis) and Sydney blue gum (E. saligna), was around 10 kg m(-2). Percentage leaf mass of these species was small (8-9%) compared with 25% and 29% for the relatively slow-growing river she-oak (Casuarina cunninghamiana) and radiata pine (Pinus radiata). Accumulation of nutrients in the total biomass differed significantly between species and ranged from 34-54 g m(-2) for nitrogen, 4.0-10.4 g m(-2) for phosphorus, 2.1-12.2 g m(-2) for sodium, 22-34 g m(-2) for potassium, 12-61 g m(-2) for calcium and 4.7-9.3 g m(-2) for magnesium. River she-oak and river red gum (E. camaldulensis), because of their relatively large crown and litter masses, accumulated more nitrogen, phosphorus, potassium and calcium than flooded gum or Sydney blue gum. Chemical properties of soils (0-150 cm) were measured in 1980 and again in 1984. Irrigation significantly increased pH (by around 1 unit), throughout the profile. Concentrations of total phosphorus, and exchangeable sodium, calcium and magnesium were increased in the upper profile. Overall, soil chemical properties were not adversely affected by effluent irrigation over the 4-year period, though there was a trend towards more sodic conditions in the soil profile. Nutrient accumulation in soil occurred mainly in the 0-35 cm depth, coinciding with the main root zone of the trees. Renovation of the effluent was therefore estimated as the amount of each nutrient accumulated in the biomass (averaged over the seven species) plus soil (0-35 cm), expressed as a percentage of amount applied in irrigation over the 4 years; that is, nitrogen, 29%; phosphorus, 78%; sodium, 15%; potassium, 26%; calcium, 98% and magnesium, 54%.     

Effectiveness of Management Interventions to Control Invasion by Rhododendron ponticum

Rhododendron ponticum is an invasive species in many countries, including the United Kingdom, Ireland, Belgium, and France. It poses a serious threat to native flora and fauna, as it is capable of altering entire seminatural communities through its vigorous spread. Control is essential if the conservation value of some communities, such as oak woodland and lowland heath, are to be successfully maintained. Commonly used interventions are herbicide application, herbicide application postcut, and cutting (manual or mechanical) alone. Various techniques have been developed to apply these interventions, but often retreatment of the area is required, increasing the cost of control. Here, we evaluate the effectiveness of some commonly used interventions for R. ponticum control using a systematic review methodology. Eleven studies provided data for statistical analysis. Meta-analyses of captured data show that postcut application of the herbicide Glyphosate or applying the herbicides Metsulfuron-methyl or Imazapyr (no cut) can effectively reduce a R. ponticum stand. There is insufficient available experimental evidence for effectiveness of any other intervention. The systematic review process has demonstrated the lack of replicated studies with controls or long-term monitoring and increases the call for more rigorous monitoring of all conservation management interventions. The quality of experimental evidence of the effectiveness of some interventions contrasts with the acceptance of their use through dissemination of experience. The collection and objective review of experience will require active collaboration of organizations concerned with R. ponticum control.     

The effectiveness of surrogate taxa to conserve freshwater biodiversity

Establishing protected areas has long been an effective conservation strategy and is often based on readily surveyed species. The potential of any freshwater taxa to be a surrogate for other aquatic groups has not been explored fully. We compiled occurrence data on 72 species of freshwater fishes, amphibians, mussels, and aquatic reptiles for the Great Plains, Wyoming (U.S.A.). We used hierarchical Bayesian multispecies mixture models and MaxEnt models to describe species’ distributions and the program Zonation to identify areas of conservation priority for each aquatic group. The landscape‐scale factors that best characterized aquatic species’ distributions differed among groups. There was low agreement and congruence among taxa‐specific conservation priorities (<20%), meaning no surrogate priority areas would include or protect the best habitats of other aquatic taxa. Common, wideranging aquatic species were included in taxa‐specific priority areas, but rare freshwater species were not included. Thus, the development of conservation priorities based on a single freshwater aquatic group would not protect all species in the other aquatic groups.     

Areal distribution of 129I in west cumbrian solis

¹²⁹I has been released during operations at the BNFL nuclear fuel reprocessing plant at Sellafield in west Cumbria over the past thirty years with about 95% being discharged into the sea and 5% into the atmosphere. Soil samples have been taken within a 40 km radius of Sellafield to determine the extent to which the ¹²⁹I is deposited in the immediate vicinity of the plant. The ¹²⁹I content has been determined by a sensitive neutron activation technique and levels in soil were found to be elevated above global levels in all samples. The areal distribution of ¹²⁹I was consistent with direct deposition following release to the atmosphere from Sellafield and the relationship between ¹²⁹I activity and the distance from Sellafield was of a form predicted by atmospheric dispersion models. The absence of any observable return of ¹²⁹I from the sea has implications for assessments of dose.     

LONGITUDINAL AND SEASONAL WATER CHEMISTRY VARIATIONS IN A NORTHERN APPALACHIAN STREAM1

ABSTRACT: Quaker Run, a fourth order stream located in southwestern New York State, exhibits a highly unusual chemical gradient along its upper reaches. Weekly water samples showed an increase in the mean annual pH from 5.07 to 7.01 along a stretch of only 2.2 km. Mean alkalinity, calcium, magnesium, sodium, potassium, nitrate-nitrite-nitrogen, silica, and conductivity also increased appreciably over this distance. The study area receives some of the most highly acidic atmospheric deposition in the United States. Minimal buffering of these acidic inputs in the extreme upper watershed, and an abrupt downstream increase in buffering associated with changes in soil type, apparently produce the observed streamwater chemistry gradient. In contrast, a comparison between 11 midstream, downstream, and tributary sites showed relatively little variation in streamwater chemistry. In addition to the pronounced longitudinal chemistry changes along the upper portion of the stream, pronounced temporal chemistry variations were also observed at all sampling sites. High flow during snowmelt and heavy rains produced more dilute, acidic conditions, while streamwater pH and dissolved base cations were generally highest during low flow. Much of this temporal variation in streamwater chemistry is attributed to seasonal variation in residence times of soil water.     

Failure to detect fetal obstructive uropathy by second trimester ultrasound

The prenatal diagnosis, management and outcome of an hereditary obstructive uropathy is presented. Serial ultrasonic assessment of the fetal urinary tract was carried out from the early second trimester onward. Slight bilateral hydronephrosis as a first sign of obstructive uropathy was only established as late as 30 weeks of gestation. On the basis of weekly ultrasound scans, a conservative approach was adopted. In view of fetal maturity, labour was induced at 36 weeks resulting in the vaginal delivery of a male infant with moderate bilateral hydronephrosis. Neonatally, anuria developed due to bilateral obstruction of the ureters as a result of increasing bladder wall hypertrophy due to urethral valves. A bilateral uretero-cutaneostomy was carried out. The infant so far develops normally, and renal function is normal for age. Women at risk for fetal obstructive uropathy should have ultrasonic monitoring throughout pregnancy.