Disturbance of benthic species by fishing activities: a sensitivity index     

DAVID S. MACDONALD  MICHAEL LITTLE  N. CLARE ENO  KEITH HISCOCK 《水产资源保护:海洋与淡水生态系统》1996,6(4):257-268

1. Preliminary estimates of the relative sensitivity of sea bed types and benthic species to physical disturbance, particularly fishing activity, have been made in order to identify areas where further studies are required and to help formulate management plans for sites of marine conservation importance. 2. Physical disturbance is considered in the context of a single encounter with fishing gear followed by a recovery period during which there is no fishing, but with a view to qualifying, in the future, the effect of multiple fishing events. Disturbance is considered in terms of the physical action of the gear on the sea bed and the unit area over which this action occurs. 3. The effects of a wide range of gears are considered. Static gears, which can be employed on a variety of substrata, generally result in low level impacts for single fishing events and impacts are localized compared with the effects of mobile gears, which can extend over considerable areas. 4. The theoretical sensitivity of individual species is assessed on the basis of how well they cope with an encounter with fishing gear and on their likely recovery from destruction in terms of their reproductive strategies. 5. Species considered of key importance in the structuring of communities are suggested and examples of particularly sensitive species, which are therefore likely indicator species of physical disturbance, are listed. 6. Fragile, slow recruiting animals are considered to be most susceptible to disturbance, while the least sensitive species are generally fast growing and have good recruitment. ©1996 by John Wiley & Sons, Ltd.  相似文献   

Repair of Complete Dorsal Fracture of the Proximal Phalanx in Two Horses     

JULIE E. DECHANT DVM    DAVID G. MACDONALD DVM  MVSC  Diplomate ACVS  WILLIAM H. CRAWFORD DVM  MVSC  Diplomate ACVS 《Veterinary surgery : VS》1998,27(5):445-449

Simple complete dorsal fractures of the proximal phalanx were repaired in 2 mature pleasure horses with cortical bone screws placed in lag fashion. Healing occurred within 12 weeks and both horses returned to their previous performance level of light pleasure riding within 6 months of injury.  相似文献   

The abundance of juvenile yellowtail (Seriola quinqueradiata) near the Kuroshio: the roles of drifting seaweed and regional hydrography     

SHINJI UEHARA  CHRISTOPHER T. TAGGART  TAKUMI MITANI  IAIN M. SUTHERS 《Fisheries Oceanography》2006,15(5):351-362

We assess the effect of drifting seaweed (Sargassum sp.) biomass, geography and hydrography on juvenile yellowtail (Seriola quinqueradiata) abundance variation off the southeast coast of Japan, near the Kuroshio Current. The amount of drifting seaweed mats progressively increased northeastward into the cooler, coastal waters. Frontal structure indexed using a station‐to‐station ΔSST did not explain spatial variation in the seaweed mat distribution, although the western extent of the Kuroshio Current appeared to act as a boundary. Juvenile yellowtail constituted 51–62% of the fish collected in association with drifting seaweed mats in April 1996 and 1997 and 29% in June 1996. The abundance of juvenile yellowtail was positively correlated with seaweed biomass. The geographic distribution of juvenile yellowtail associated with drifting mats varied among sampling periods, being more southwesterly in April and more northeasterly in June. Simple multiple regression models based on seaweed biomass and geographic distribution (latitude) explained between 35% and 43% of the variation in juvenile yellowtail abundance in spring. Associations with spatial and temporal variations in hydrographic conditions did not contribute to explained variation in a meaningful manner. The results presented here indicate that, off the southeast coast of Japan during April, yellowtail juveniles are likely to be most abundant when seaweed biomass is high, occur offshore, and are bounded by the western extent of the Kuroshio Current near the 19–20°C SST isotherm.  相似文献   

Norway or Sitka Spruce?     

MACDONALD  J. A. B. 《Forestry》1967,40(2):129-138

The deep and wide continental range and climate occupied bythe European species Picea abies is contrasted with the long,narrow, and humid coastal strip which the American species Piceasitchensis inhabits. Norway is the more plastic spruce and cansuffer thinner soils and much more drought, but neither spruceis a shallow rooter where soils are good and deep. Of the two,the litter of Sitka is less harmful to the soil. To date thereis no evidence that height for height Norway is more stableunder high wind pressures, but the belief that it is less sensitiveto frost than Sitka is well established. Sitka is far superiorto Norway for planting at high altitudes and in exposed placesand on Molinia peatlands in Britain, which accounts for thevast preponderance of the American species used in the westand north of the British Isles. The present popularity of Norwayspruce with foresters and timber merchants is admitted, butthe point is made that in planting it where Sitka could growwell, only some 75 per cent, of the volume will be secured.Finally, the types of site which each spruce requires and alsowhich each cannot take are considered in detail. A plea is madefor mixtures in certain circumstances, and the belief expoundedthat only deeper and better cultivation of the hardpacked materialunder-lying thin soils will make it possible to extend considerablyour acreage of really stable crops of these high-volume producers.  相似文献   

EVALUATION OF MAGNETIC RESONANCE SAFETY OF VETERINARY RADIOFREQUENCY IDENTIFICATION DEVICES AT 1 T     

MARTIN A. BAKER  IAIN MACDONALD 《Veterinary radiology & ultrasound》2011,52(2):161-167

Implants containing metallic components have the potential to become heated or move within the patient while in the magnetic resonance (MR) environment. Despite containing a ferromagnetic core and having been in use for over 20 years, no information is available on the safety of veterinary radiofrequency identification devices during MR examinations. These devices are the most commonly encountered metallic implants in dogs and cats undergoing MR imaging. Three commercial veterinary microchips were evaluated for safety in the MR environment at 1 T. Parameters tested were translational force, torque, heating, artifact production, and function. Translation and torque were larger than that expected from normal activity under normal gravity. No significant heating was observed. Signal void artifacts may affect diagnosis if they are too close to the area of clinical importance. Microchip function was unaffected by routine clinical MR imaging. Capsule formation around devices is a major factor in counteracting translation and torque. Our findings support that is acceptable for patients to undergo MR imaging with this 1 T system following an interval of 3 months postimplantation to allow capsule growth. Because of the complex interactions involved, these observations may not be translatable to MR scanners of different field strength and/or manufacturer. Further safety testing of these and other radiofrequency identification devices is therefore recommended at different field strengths and equipment specifications.  相似文献   

THIRTY YEARS' DEVELOPMENT OF AFFORESTATION TECHNIQUES ON DIFFICULT GROUND TYPES IN SOUTH-WEST SCOTLAND     

MACDONALD  J. A. B. 《Forestry》1953,26(1):14-21

The development of ploughing, draining, planting, and the useof turfs and of phosphate is considered in detail for each oftwo main types. For Molinia lands, the 1952 technique securesadequate drainage and a very considerable turnover of turf,and here the spruces Picea abies Karst. and P. sitcbensis Carr.remain the first choice. For Calluna lands, the developmentof methods and the choice of species is more difficult. Thespruces refuse to grow pure and unnursed on the poorer Callunatypes and the use of Scots pine (Pinus sylvestris L.), P. contortaDoug., the Mountain pine (P. uncinata Ramond), Japanese larch(Larix leptolepis Gord.), and Douglas fir (Pseudotsuga taxifoliaBrit.) is discussed. The main requirements for successful afforestationof these ground types are summarized.  相似文献   

Replication of infectious pancreatic necrosis virus in trout leucocytes and detection of the carrier state     

K.K-Y. YU  R.D. MACDONALD  ANNE R. MOORE 《Journal of fish diseases》1982,5(5):401-410

Abstract. The exact cellular site of replication of infectious pancreatic necrosis virus (IPNV) in carrier fish is unknown. In order to determine if IPNV replicates in trout leucocytes, we purified leucocytes from normal (non-carrier) trout and separated the cells into an adherent and a non-adherent population. IPNV replicated in less than 0-01 % of the adherent leucocytes with a yield of about 400 p.f.u./cell. IPNV also became associated with less than 0.07% of the non-adherent leucocytes; either IPNV did not replicate in these cells or the yield was, at best, only a few p.f.u./cell. Trout persistently infected with IPNV (carrier fish) were tested for the presence of IPNV in leucocytes by co-cultivating with a sensitive fish cell line; this same population of trout was also tested for IPNV by organ sampling using standard methods. Ninety-eight per cent of the trout were positive for IPNV by organ sampling, but only 75 % yielded IPNV from leucocytes. Thus a blood sample from a living fish can be used to detect the presence of IPNV.  相似文献   

The use of the random amplified polymorphic DNA technique to identify mating groups in the Fusarium section Liseola     

B. K. AMOAH  M. V. MACDONALD  N. REZANOOR  & P. NICHOLSON 《Plant pathology》1996,45(1):115-125

The random amplified polymorphic DNA (RAPD) technique was used to determine the mating groups of several members of the Fusarium section Liseola recovered from maize, rice and sorghum collected from different locations in Ghana. Three mating groups were identified, A, D and F, of which all A and F isolates were confirmed by mating studies. Fertile crosses were also obtained in crosses involving two of the isolates identified as belonging to the D population. Variability within the A population isolated from seeds and stem-bases of maize was investigated to determine whether the sub-structuring of this population was related to the host tissue from which the isolates were obtained. The relative merits of the RAPD procedure, compared to the mating procedure, for determining the mating affiliations of isolates and for more detailed analyses of isolates within a population, as well as its possible advantages over established RFLP methodologies are discussed.  相似文献   

Flea Control: An Overview of Treatment Concepts for North America   总被引：2，自引：0，他引：2  

JOHN M. MACDONALD 《Veterinary dermatology》1995,6(3):121-130

Résumé— L'approche d'un contrôle anti puces souligne Pimportance de la communication entre le vétérinaire et le propriétaire d'un animal de compagnie, communication qui implique la connaissance de chaque cas de figure individuel. Une revue des antiparasitaires usuels est brièvement présentée incluant les principes actifs et leur classification. Les concepts de mise en place d'un programme de contrôle anti puces qui sont présentés incluent aussi bien les aspects de contrôle des puces à l'intérieur des habitations et dans le milieu exérieur, que les produits et méthodes utilisées pour traiter l'animal. Les produits les plus récents utilisés dans la lutte antipuces sont présentés, comme les régulateurs de croissance des insectes, les inhibiteurs de croissance des insectes, les traitements utilisant des nématodes, et les composés à base de borate. [MacDon-ald, J. M. Flea control: an overview of treatment concepts for North America (Contrôle antipuces: revue des concepts de traitement en Amérique du Nord). Resumen— El enfoque al control de pulgas pone de manifiesto la importancia de la interrelación entre el veterinario y el propietario del animal, siendo necesario un conocimiento de las condiciones especiales en casos individuales. Se presenta una breve revisión de los parasiticidas más comunes, con un listado de los compuestos activos y su clasificación. Se presentan los principios para el diseño de un programa de control de pulgas, incluyendo el control dentro y fuera de la vivienda, asi como productos y métodos para tratar el animal. Se revisan los productos más recientes utilizados para el control de pulgas como reguladores del crecimiento de insectos, reguladores del desarrollo de insectos, tratamiento de nemátodos y compuestos de borato. [MacDonald, J. M. Flea control: an overview of treatment concepts for North America (Control de pulgas: un repaso a los principios sobre tratamiento en Norte-América). Abstract— The approach to flea control emphasizes the importance of interrelationships between veterinarian and pet owner requiring knowledge of the unique environment of individual cases. A review of common parasiticides is briefly presented listing active ingredients and their classification. Concepts of developing a flea control program are presented that include aspects of inside and outside flea control as well as products and methods used to treat the pet. Newer products used in flea control are reviewed including insect growth regulators, insect development inhibitors, nematode treatment and borate compounds.  相似文献   

NOTES ON FORESTRY IN SICILY     

MACDONALD  JAMES 《Forestry》1955,28(2):81-93

An account, by a delegate from Great Britain to the eleventhCongress of the International Union of Forest Research Organizationsheld in Rome in 1953, of some aspects of the work being undertakenby the Government of Sicily to restore fertility to degradedsoils and thereby prosperity to the island by the control oftorrents and by afforestation in the torrid climate of the mountainsof southern Europe.  相似文献