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

Vicki L Stokes  Roger P Pech  Anthony D Arthur 《Biological conservation》2004,117(3):331-342

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.  相似文献   

Acute effects of wood-pulp on sockeye salmon (Oncorhynchus Nerka)     

Arthur E. Werner  Jack Robinson 《Water, air, and soil pollution》1978,9(1):69-81

Freshwater suspensions of pulp fiber in concentrations exceeding 1000 ppm at 15°C are acutely lethal to sockeye salmon fingerlings. Limited adaptation of such fish to fiber is possible but injury, at least in the short term, is irreversible. The acute lethality of various toxicants associated with industrial pulps is synergistically enhanced by the presence of fiber, and pulp storage up to 158 days at 15°C had no significant effect on the acute lethality. Highly purified fibers are less toxic in fresh than in sea water. The sensitivity to fiber of fish from two sources did not differ significantly.  相似文献   

Book reviews     

K. C. Pillai  Arthur C. Stern  T. Viraraghavan  Michel Benarie  G. F. Humphrey  D. P. Ormrod  Jan S. M. Boleij  Michael Waldichuk  Jan Smeets 《Water, air, and soil pollution》1985,26(3):307-326

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The long way down--are carbon and oxygen isotope signals in the tree ring uncoupled from canopy physiological processes?     

Offermann C  Ferrio JP  Holst J  Grote R  Siegwolf R  Kayler Z  Gessler A 《Tree physiology》2011,31(10):1088-1102

The carbon (δ(13)C) and oxygen (δ(18)O) stable isotope composition is widely used to obtain information on the linkages between environmental drivers and tree physiology over various time scales. The tree-ring archive can especially be exploited to reconstruct inter- and intra-annual variation of both climate and physiology. There is, however, a lack of information on the processes potentially affecting δ(13)C and δ(18)O on their way from assimilation in the leaf to the tree ring. As a consequence, the aim of this study was to trace the isotope signals in European beech (Fagus sylvatica L.) from leaf water (δ(18)O) and leaf assimilates (δ(13)C and δ(18)O) to tree-ring wood via phloem-transported compounds over a whole growing season. Phloem and leaf samples for δ(13)C and δ(18)O analyses as well as soil water, xylem water, leaf water and atmospheric water vapour samples for δ(18)O analysis were taken approximately every 2 weeks during the growing season of 2007. The δ(13)C and δ(18)O samples from the tree rings were dated intra-annually by monitoring the tree growth with dendrometers. δ(18)O in the phloem organic matter and tree-ring whole wood was not positively related to leaf water evaporative enrichment and δ(18)O of canopy organic matter pools. This finding implies a partial uncoupling of the tree-ring oxygen isotopic signal from canopy physiology. At the same time, internal carbon storage and remobilization physiology most likely prevented δ(13)C in tree-ring whole wood from being closely related to intra-annual variation in environmental drivers. Taking into account the post-photosynthetic isotope fractionation processes resulting in alterations of δ(13)C and δ(18)O not only in the tree ring but also in phloem carbohydrates, as well as the intra-annual timing of changes in the tree internal physiology, might help to better understand the meaning of the tree-ring isotope signal not only intra- but also inter-annually.  相似文献   

Hydrologic pathways and chemical composition of runoff during snowmelt in Loch Vale Watershed,Rocky Mountain National Park,Colorado, USA     

A. Scott Denning  Jill Baron  M. Alisa Mast  Mary Arthur 《Water, air, and soil pollution》1991,59(1-2):107-123

Intensive sampling of a stream draining an alpine-subalpine basin revealed that depressions in pH and acid neutralizing capacity (ANC) of surface water at the beginning of the spring snowmelt in 1987 and 1988 were not accompanied by increases in strong acid anions, and that surface waters did not become acidic (ANC<0). Samples of meltwater collected at the base of the snowpack in 1987 were acidic and exhibited distinct ‘pulses’ of nitrate and sulfate. Solutions collected with lysimeters in forest soils adjacent to the stream revealed high levels of dissolved organic carbon (DOC) and total Al. Peaks in concentration of DOC, Al, and nutrient species in the stream samples indicate a flush of soil solution into the surface water at the beginning of the melt. Infiltration of meltwater into soils and spatial heterogeneity in the timing of melting across the basin prevented stream and lake waters from becoming acidic.  相似文献   

Quantitative extraction of macro-invertebrates from temperate and tropical leaf litter and soil: efficiency and time-dependent taxonomic biases of the Winkler extraction   总被引：2，自引：0，他引：2  

Frank-Thorsten Krell  Arthur Y.C. Chung  Emma DeBoise  Paul Eggleton  Alessandro Giusti  Kelly Inward  Sylvia Krell-Westerwalbesloh 《Pedobiologia》2005,49(2):175-186

Winkler extractors, a simple device presumed to extract macro-invertebrates efficiently from soil and litter samples, is being used increasingly in ecological surveys and functional studies of soil macro-invertebrate communities. In this study the extraction efficiency and taxonomic bias of the Winkler extraction are evaluated for extraction periods of 3 h up to 7 weeks, calibrated by hand-sorting after 7 weeks. The method extracts most macro-invertebrates completely or to a proportion of over 90% except Isopoda, Diplopoda and Mollusca. However, for an exhaustive result, a long extraction period of several weeks is necessary. For the most speciose group (adult beetles) and for the commonly most abundant group (ants), a short extraction of 3 days was sufficient to get 70% of the individuals and nearly all species. Three days was also sufficient to recover the rank abundance order of beetle families, while for ‘higher taxa’ and for Chilopoda species, 4 and 3 weeks were necessary, respectively. Optimum extraction times for the abundant macro-invertebrate groups and possible adjustment factors for the soil macro-invertebrates of temperate woodlands are proposed to compensate the taxonomic bias caused by short extraction periods. However, for recording an accurate snapshot of the soil and litter fauna at a particular time, shorter extraction periods are advisable because of the short life cycle of many soil invertebrates causing emergence of later stages or a second generation during longer extraction periods. The problem of contamination of samples is also discussed.  相似文献   

Clusters of hyperactive neurons near amyloid plaques in a mouse model of Alzheimer's disease     

Busche MA  Eichhoff G  Adelsberger H  Abramowski D  Wiederhold KH  Haass C  Staufenbiel M  Konnerth A  Garaschuk O 《Science (New York, N.Y.)》2008,321(5896):1686-1689

The neurodegeneration observed in Alzheimer's disease has been associated with synaptic dismantling and progressive decrease in neuronal activity. We tested this hypothesis in vivo by using two-photon Ca2+ imaging in a mouse model of Alzheimer's disease. Although a decrease in neuronal activity was seen in 29% of layer 2/3 cortical neurons, 21% of neurons displayed an unexpected increase in the frequency of spontaneous Ca2+ transients. These "hyperactive" neurons were found exclusively near the plaques of amyloid beta-depositing mice. The hyperactivity appeared to be due to a relative decrease in synaptic inhibition. Thus, we suggest that a redistribution of synaptic drive between silent and hyperactive neurons, rather than an overall decrease in synaptic activity, provides a mechanism for the disturbed cortical function in Alzheimer's disease.  相似文献   

Co-funding in Canada: another view     

Carty AJ 《Science (New York, N.Y.)》2005,309(5736):874-875

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Ephedra-free is not danger-free     

Marcus DM  Grollman AP 《Science (New York, N.Y.)》2003,301(5640):1669-71; author reply 1669-71

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Wireless solar water splitting using silicon-based semiconductors and earth-abundant catalysts     

Reece SY  Hamel JA  Sung K  Jarvi TD  Esswein AJ  Pijpers JJ  Nocera DG 《Science (New York, N.Y.)》2011,334(6056):645-648

We describe the development of solar water-splitting cells comprising earth-abundant elements that operate in near-neutral pH conditions, both with and without connecting wires. The cells consist of a triple junction, amorphous silicon photovoltaic interfaced to hydrogen- and oxygen-evolving catalysts made from an alloy of earth-abundant metals and a cobalt|borate catalyst, respectively. The devices described here carry out the solar-driven water-splitting reaction at efficiencies of 4.7% for a wired configuration and 2.5% for a wireless configuration when illuminated with 1 sun (100 milliwatts per square centimeter) of air mass 1.5 simulated sunlight. Fuel-forming catalysts interfaced with light-harvesting semiconductors afford a pathway to direct solar-to-fuels conversion that captures many of the basic functional elements of a leaf.  相似文献