Seasonal and temperature dependence of photosynthesis and respiration for two co-occurring broad-leaved tree species with contrasting leaf phenology

We measured the seasonal and temperature responses of leaf photosynthesis and respiration of two co-occurring native New Zealand tree species with contrasting leaf phenology: winter-deciduous fuchsia (Fuchsia excorticata J. R. Forst & G. Forst) and annual evergreen wineberry (Aristotelia serrata J. R. Forst & G. Forst). There was no difference in the amount of nitrogen per unit leaf area (Narea, range 40-160 mmol m-2, P = 0.18) or specific leaf area (S, range 8-27 m2 kg-1, P = 0.87) in summer leaves of wineberry or fuchsia. The amount of nitrogen per unit leaf area and S varied significantly with height of leaves in the canopy for both species (r2 range 0.61-0.87). Parameters describing the maximum rates of rubisco carboxylation (Vcmax) and electron transport (Jmax) were related significantly to Narea, and were 60% higher on average in spring and summer leaves than in autumn and winter leaves for both species. The seasonal effect remained significant (P < 0.001) when Narea was included in a regression model, indicating that seasonal changes were not only due to changes in Narea. Values for Vcmax and Jmax were 30% lower in wineberry leaves than in fuchsia leaves on average, although the difference ranged from 15% in summer leaves to 39% in autumn leaves. Activation energies describing the temperature dependence of Vcmax and Jmax in wineberry were 111 and 114% of corresponding values for fuchsia (Ea (Vcmax) = 39.1 kJ mol-1, Ea (Jmax) = 32.9 kJ mol-1). Respiration at night was the same (P = 0.34) at 10 degrees C for both species (R10 = 0.7 micromol m-2 s-1), although activation energies (E0) were higher in wineberry than in fuchsia (47.4 and 32.9 kJ mol-1 K-1, respectively). These results show that rates of photosynthesis are higher in winter-deciduous fuchsia than in annual evergreen wineberry.     

Water quality changes in sudbury area lakes: A comparison of synoptic surveys in 1974–1976 and 1981–1983

A survey was carried out during the summers of 1981–1983 to re-sample 209 Sudbury, Ontario area lakes originally sampled in 1974–1976. Between the study periods, SO₂ emissions from the Sudbury metal smelters were reduced by ～ 50%. Observed water quality changes included increases in pH and decreases in SO₄ ^?, Ni, and Cu concentrations. The degree of observed changes showed a general relationship to distance from the Sudbury smelters, indicating that reduced contaminant deposition from Sudbury sources was responsible for the observed improvements. Although changes in water quality have occurred in many Sudbury area lakes over the course of this study, many lakes remain acidic and metal-contaminated.     

Foraging behaviour and habitat use by Antechinus flavipes and Sminthopsis murina (Marsupialia: Dasyuridae) in response to predation risk in eucalypt woodland

We examined the foraging behaviour and habitat use of two species of small Australian mammal (Antechinus flavipes and Sminthopsis murina) in response to predation risk in remnant eucalypt woodland. Predation risk was manipulated by providing refuge in the form of ground level wire netting to reduce risks from avian and mammalian predators. Giving-up-densities (GUD) using artificial food trays (20 mealworms in 1.5 l vermiculite) quantified the foraging behaviour in response to predation risk, by measuring the quitting harvest rate. Both A. flavipes and S. murina had lower GUDs (number of mealworms remaining) under the netting than in the open, most likely because these areas have lower predation risk. Animals also made greater visits to tracking tunnels under the netting compared to in the open. Tracking animal movements using fluorescent pigments also revealed preference for natural microhabitats that were structurally complex with animals moving most where logs and rock crevices were present. These results suggest that small mammals may use habitat structure to reduce their risks of predation. If future studies are able to demonstrate commensurate population-level responses, manipulation of habitat may be a useful management option to complement the direct control of exotic predators such as foxes and feral cats.     

Phenolic composition of champagnes from Chardonnay and Pinot Noir vintages

Nineteen phenolic compounds including hydroxybenzoic acids, hydroxycinnamic acids, flavonoids, phenolic alcohols, and phenolic aldehydes have been identified and quantified in two monovarietal champagnes, Chardonnay and Pinot Noir, by using a reverse-phase high-performance liquid chromatography (HPLC) system coupled with diode array detection. The identification of four hydroxycinnamic tartaric esters (caftaric, coutaric, fertaric, and 2-S-glutathionylcaftaric acids), two flavanonols (astilbin and engeletin), and some other compounds was confirmed by HPLC coupled with mass spectrometry. Caftaric acid and tyrosol were the major phenols. Hydroxybenzoic acids and flavonoids were present at low concentrations. The phenolic compositions of 2000 and 2001 Chardonnay and Pinot Noir vary quantitatively according to the year and the variety, but the chemical natures of the molecules are the same. The total phenolic content determined by colorimetric measurement ranges from 176 to 195 mg/L of gallic acid equivalent and is similar to that described in white wines.     

The evaluation of permethrin for wood preservation

The toxicity of the synthetic pyrethroid permethrin (NRDC 143) to a range of wood destroying insects has been investigated. In tests using Hylotrupes bajulus, Anobium punctatum, Lyctus brunneus and Reticulitermes santonensis permethrin showed a similar order of toxicity to that of gamma-BHC. Although the toxicity of permethrin to adult A. punctatum was of the same order as that of gamma-BHC, the toxicity to larvae was rather lower. The implications of these results are discussed and it is concluded that, subject to further field evaluation, permethrin could provide an alternative to gamma-BHC and dieldrin in wood preservatives.     

Transstadial and intrastadial experimental transmission of Ehrlichia canis by male Rhipicephalus sanguineus

The acquisition and transmission of rickettsial pathogens by different tick developmental stages has important epidemiological implications. The purpose of this study was to determine if male Rhipicephalus sanguineus can experimentally acquire and transmit Ehrlichia canis in the absence of female ticks. Two trials were performed where nymphal and male R. sanguineus were simultaneously acquisition fed on the same infected donor hosts, and transstadially or intrastadially exposed male ticks were fed on separate pathogen-free dogs as a test for transmission. A single-step p30-based PCR assay was used to test canine and tick hosts for E. canis infections before and after tick feeding. E. canis was detected after either intrastadial or transstadial passage in male ticks, the organism remained detectable in both tick groups after transmission feeding, and both tick groups transmitted the rickettsia to susceptible dogs. Infection of dogs via tick feeding resulted in milder clinical signs and lower antibody titers than intravenous inoculation of carrier blood, but further investigation is needed to understand the mechanisms responsible for this observation. These results demonstrate that male R. sanguineus can take multiple feedings, and that they can both acquire and transmit E. canis in the absence of female ticks. This tick development stage could be important in transmission of E. canis, and perhaps related pathogens, between vertebrate hosts under natural and experimental conditions.