Effects of urbanization on California’s fish diversity: Differentiation, homogenization and the influence of spatial scale     

Michael P. Marchetti  Julie L. Lockwood 《Biological conservation》2006,127(3):310-318

Human development of freshwater ecosystems has lead to drastic changes in freshwater fish faunas, including the loss of many native species and the gain of non-natives. Typically conservation ecologists view these two opposing forces as contributing to biological homogenization, and consider homogenization as one of the principle negative consequences of urbanization. However, homogenization is only one outcome out of many that can result from the loss and gain of species. In particular, it is possible for invasions and extinctions to lead to differentiation; a process whereby two (or more) regions become less similar to one another through time. Using the freshwater fishes of California, we show that urbanization is highly positively correlated to both the endangerment of native fish and the invasion of non-native fish within watersheds. Despite this, the fish faunas of California’s watersheds have differentiated from one another through time. Furthermore, the degree of differentiation is positively correlated with measures of urbanization, which is contrary to expectation. We suggest that this result reflects: (1) the haphazard manner in which non-native fishes have been introduced into California watersheds, (2) the difficulty that both native and non-native fishes have in expanding their geographical ranges, and (3) the continued presence of vestiges of formerly distinct regional faunas. This pattern of differentiation among watersheds is likely a matter of scale, as previous work on freshwater fishes has demonstrated homogenization at both larger and smaller spatial scales. In addition the observed pattern is probably a short-term (temporal) phenomena and will disappear with continued invasion and extinction. We suggest that similar patterns may occur for other taxa that have limited natural dispersal abilities and that are idiosyncratically released as non-natives via human activities (e.g. herptiles).  相似文献   

Does the matrix matter? A forest primate in a complex agricultural landscape   总被引：1，自引：0，他引：1  

Julie Anderson  J. Marcus Rowcliffe 《Biological conservation》2007,135(2):212-222

Many threatened primates now exist in fragmented forest habitats. The survival of these populations may depend on their ability to utilise agricultural or other matrix habitats between forest fragments, but this is poorly known. Here, we systematically investigate an arboreal primate’s use of a heterogeneous matrix in a fragmented forest landscape: the Angola black-and-white colobus (Colobus angolensis palliatus) in southern Kenya. We used a novel technique, based on semi-structured interviews with local informants, to address the difficulty of sampling relatively rare but important events, such as dispersal between fragments. We found that colobus frequently travelled and foraged in indigenous matrix vegetation (such as mangrove, wooded shrubland and shrubland) up to 4 km from the nearest forest fragments. Agricultural habitats, such as perennial plantation (coconut, mango and cashew nut) were also used by colobus for travelling and foraging (in remnant indigenous trees). The probability of sighting colobus in the matrix increased with the proportion of both tall (>6 m) vegetation cover and food tree cover, but declined with distance from forest habitat. Our findings suggest that certain matrix habitats are important for C. a. palliatus, and that future primate conservation initiatives might benefit from adopting a ‘landscape-level’ approach to habitat management, particularly in fragmented forest systems.  相似文献   

Development of a Two-Phase Cosolvent Washing-Fungal Biosorption Process for the Remediation of DDT-Contaminated Soil     

Juhasz  Albert L.  Smith  Euan  Smith  Julie  Naidu  Ravendra 《Water, air, and soil pollution》2003,146(1-4):111-126

A bench scale, two-phase soil washing-biosorption process was developed for the remediation of p,p′-DDT-contaminated soil (containing 990 and 7750 mg kg^-1 of p,p′-DDT). Removal of p,p′-DDT from contaminated soil was achieved by washing the soil with low molecular weight primary alcohols (ethanol or 1-propanol). An improved efficiency of p,p′-DDT removal was observed with increasing C-chain length of the cosolvent and by increasing the cosolvent volume fraction. When 40 or 80% 1-propanol were used, greater than 93% of p,p′-DDT was desorbed from the respective soils. p,p′-DDT was partitioned from the cosolvent solutions using biomass of Cladosporium sp. strain AJR³18,501 as the sorptivematrix. When studies were conducted using a cosolvent-recycling regime (with 80% 1-propanol) greater than 95% of p,p′-DDT was removed from Soil A (990 mg kg^-1 p,p′-DDT) and Soil B (7750 mg kg^-1 p,p′-DDT) with the majority of the desorbed organochlorine repartitioning onto the fungal biomass. Less than 2.4 μg mL^-1 p,p′-DDT was detected in the cosolvent wash solution of Soil A after 80 hr: potentially the cosolvent could be further reused to treat other soil. A higher concentration of p,p′-DDT was detected in the cosolvent wash solution of soil B after 120 hr (13.3 μg mL^-1) indicating that the p,p′-DDT sorption sites on the fungal biomass were fully saturated.  相似文献   

In situ Remediation of DDT-contaminated Soil Using a Two-Phase Cosolvent Flushing-Fungal Biosorption Process     

Juhasz  Albert L.  Smith  Euan  Smith  Julie  Naidu  Ravendra 《Water, air, and soil pollution》2003,147(1-4):263-274

The effectiveness of cosolvent soil flushing and fungal biosorption for the remediation of p,p′-DDT-contaminated soil was evaluated usingpacked soil columns in order to simulate an in situ soil flushing technique. Greater than 95% of p,p′-DDT (940 mg kg^-1) was desorbed from the soil by flushing with 40 or 80% 1-propanol. Increasing the cosolvent volume fraction increased the rate of p,p′-DDT removal from the soil, however, the extent of p,p′-DDT removal was not enhanced. A further enhancement in therate of p,p′-DDT removal was achieved by increasing the cosolventflow rate from 6 ml hr^-1 to 12 ml hr^-1 (pore water velocity from 18.9 to 37.8 cm hr^-1). The desorbed p,p′-DDT was removed from cosolvent wash solutions by partitioning onto fungal biomass. Biosorption of p,p′-DDT resulted in low concentrations of the organochlorine (3.3 μg ml^-1) remaining in thecosolvent effluent indicating that the cosolvent could be reused for further p,p′-DDT desorption. Using this technique, between 53 and 95 pore volumes were required to reduce p,p′-DDT concentrationsfrom 990 mg kg^-1 to below Australian and New Zealand Environmentaland Conservation Council (ANZECC) guidelines (50 mg kg^-1).  相似文献   

Statistical analysis of interactive cytotoxicity in human epidermal keratinocytes following exposure to a mixture of four metals     

Chris Gennings  Walter H. Carter  Julie A. Campain  Dong-soon Bae  Raymond S. H. Yang 《Journal of Agricultural, Biological & Environmental Statistics》2002,7(1):58-73

Exposure to mixtures of chemicals is an important and relevant environmental issue. Of particular interest is the detection and characterization of departure of biological effects from additivity. Methodology based on the assumption of additivity is used in fitting single-chemicaldata. Interactionsare determined and characterized by making comparisons between the observed and predicted responses at mixtures along a fixed ratio ray of the component substances. Two simultaneous tests are developed for testing for any departure from additivity. Multiple comparisons procedures are used to compare observed responses to that predicted under additivity. A simultaneous confidence band on the predicted responses along the mixture ray is also developed. The methods are illustrated with cytotoxicity data that arise when human epidermal keratinocytes are exposed to a mixture of arsenic, chromium, cadmium, and lead. Synergistic, antagonistic, and additive cytotoxicities were observed at different dose levels of the four-metal mixture.  相似文献   

Photodynamic action of erythrosin B as a toxic mechanism for infective larvae of bovine gastrointestinal nematodes     

J A Hawkins  M H Johnson-Delivorias  J R Heitz 《Veterinary parasitology》1986,21(4):265-270

The effect of erythrosin B on adults and 3rd stage larvae of gastrointestinal nematodes of cattle was studied by treating calves per os with 20 mg kg-1, 40 mg kg-1, and 60 mg kg-1 of the dye daily for 21 days and monitoring its effect. Erythrosin B had no detectable effect on adult nematode fecundity or viability. Data collected did indicate, however, that erythrosin B produced a consistent toxic effect on 3rd stage larvae after exposure to fluorescent light. This toxic effect was dependent upon dosage of erythrosin B administered, time of light exposure and, to a much lesser extent, the length of time the larvae were left in culture in the presence of the dye.  相似文献   

The fate of dinobuton and dinoseb on growing apples     

David R. Hawkins  Valerie H. Saggers 《Pest management science》1974,5(4):497-504

After topical application of dinobuton or dinoseb to apple fruits approximately 75% and 72% respectively of the applied material was lost after 28 days. From apples treated with dinobuton the unchanged compound was the major component present up until 8 days but at later times the amounts of polar transformation products and water-soluble compounds predominated. Only small amounts of dinoseb were found at all times. A similar pattern of results was obtained from apples treated with dinoseb. The maximum amounts of material absorbed through the fruit skin were 3% from dinobuton-treated apples and 7% from dinoseb-treated applies.  相似文献   

Dactylomegaly, a type of club foot (talipes) in a herd of Shorthorn cattle     

C D Hawkins  J Grandage 《Australian veterinary journal》1983,60(2):55-56

Enlarged dew claws associated with syndactyly and/or deviation of the adjacent major digit are reported from 9 heifers in a herd of 800. The anomaly created a club-footed appearance.  相似文献   

Collection of bronchoalveolar lavage fluid in cats, using an endotracheal tube   总被引：1，自引：0，他引：1  

E C Hawkins  D B DeNicola 《American journal of veterinary research》1989,50(6):855-859

Bronchoalveolar lavage fluid was collected from 12 anesthetized cats by use of an endotracheal tube and syringe adapter. The safety of the technique was evaluated by monitoring mucous membrane color, capillary refill time, pulse rate, respiratory rate, ECG, and arterial blood gas tensions and by necropsy findings. Group A consisted of 3 cats that were administered (by lavage) 4 aliquots of 20 ml of saline solution during anesthesia for placement of femoral artery catheters. Group B consisted of 4 cats that were administered a smaller total volume of saline solution (3 aliquots of 5 ml/kg of body weight) during a separate anesthetic period, other than the one for placement of catheters. Group C consisted of 5 cats administered 3 aliquots (5 ml/kg) of saline solution during a separate anesthetic period and administered supplemental oxygen for 5 to 10 minutes before and for 20 minutes after the lavage procedure. Group-A cats had a prolonged recovery period that was attributed to the lengthy anesthetic period required for placement of femoral catheters. The effect was eliminated in the cats of the other groups in which the lavage procedure itself accounted for only 5 to 10 minutes of anesthetic time. Evaluation of mucous membrane color, capillary refill time, ECG, pulse, and respiratory rate revealed no persistent abnormalities. Transient increase in pulse and respiratory rate was seen in some cats. Blood gas analysis revealed noticeable decrease in arterial oxygen pressures (Pao2) after the lavage procedure. In group-C cats, oxygen supplementation allowed the maintenance of normal or above normal Pao2.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Digestion of bentiromide and absorption of xylose in healthy cats and absorption of xylose in cats with infiltrative intestinal disease     

E C Hawkins  S M Meric  R J Washabau  E C Feldman  J M Turrel 《American journal of veterinary research》1986,47(3):567-569

The digestion of bentiromide and the absorption of D-xylose was measured in 17 clinically healthy cats. The plasma xylose concentrations of the healthy cats were compared with values from 9 cats with diffuse infiltrative intestinal disease. The cats were administered 16.7 mg of bentiromide/kg and 0.5 g of xylose/kg via a stomach tube. Plasma samples were obtained before administration and 30, 60, 90, and 120 minutes after administration. The maximum mean plasma p-aminobenzoic acid concentration occurred at 60 minutes, with a value of 386 +/- 134 micrograms/dl (mean +/- SD). The maximum mean plasma xylose concentration also occurred at 60 minutes, with a value of 26.0 +/- 9.2 mg/dl. Plasma concentrations of p-aminobenzoic acid and xylose were lower in healthy cats than those reported for healthy dogs. There was no significant difference between xylose concentrations in healthy cats and cats with infiltrative intestinal disease.  相似文献