Seasonal growth and diet of juvenile chinook salmon (Oncorhynchus tshawytscha) in demonstration channels and the main channel of the Waitaki River, New Zealand, 1982–1983     

G. Power 《Ecology of Freshwater Fish》1992,1(1):12-25

Abstract– Juvenile chinook salmon in the Waitaki River, New Zealand and demonstration channels, living at about 16°C, increased in length by 0.32 mm day⁻¹ between 4 November and 4 March. They gained weight quickly, accumulated large visceral fat deposits and had high conditions factors. At 1600 h, stomachs averaged half full. The number of prey tended to decline as the fish grew and consumed larger items. Initially the diet was based mainly on chironomid larvae, but by December it included a diversity of prey in more equal proportions. These included Deleatidium in the Waitaki; amphipods in the demonstration channels; various trichopterans, hemipterans, elmid beetles, zooplankton. terrestrial dipterans and a variety of other prey. There were significant differences between sites in numbers of prey consumed and these probably reflected differences in the benthos. Diets in the Waitaki differ from those in the Rakaia River and the food of juvenile salmon appears closely linked to the availability of a diverse range of possible prey.  相似文献   

Serum 5'nucleotidase activity in rats: a method for automated analysis and criteria for interpretation     

Carakostas MC  Power RJ  Banerjee AK 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》1990,19(4):109-113

A manual kit for determining serum 5'nucleotidase (5'NT, EC 3.1.3.5) activity was adapted for use with rat samples on a large discrete clinical chemistry analyzer. The precision of the method was good (within-run C.V. = 2.14%; between-run C.V. = 5.5%). A comparison of the new automated method with a manual and semi-automated method gave regression statistics of y = 1.18X -3.66 (Sy. x = 4.54), and y = 0.733X + 1.97 (Sy. x = 1.69), respectively. Temperature conversion factors provided by the kit manufacturer for human samples were determined to be inaccurate for converting results from rat samples. Analysis of components contributing to normal variation in rat serum 5'NT activity showed age and sex to be major factors. Increased serum 5'NT activity was observed in female rats when compared to male rats beginning at about 5 to 6 weeks of age. An analysis of variance of serum 5'NT, alkaline phosphatase, and GGT activities observed over a 9-week period in normal rats suggests several advantages for 5'NT as a predictor of biliary lesions in rats.  相似文献   

海子水库灌区节水型灌溉制度的制定     

赵玲爽 《中国农村水利水电》1991,(7)

本文介绍了中日双方专家团在海子水库灌区现场调查中,实测土壤水分特征值的方法,土壤水分曲线的制定和应用,负压计观测值的应用,计算节水型灌溉用水量和灌水间隔日数的方法,并用节水型频繁灌溉法制定了各作物的节水型灌溉制度,用这种方法制定的节水型灌溉制度要比我国过去用的常规法节水40%以上。  相似文献   

半导体消雷器在县级电力系统中的应用     

洪希度  陈满园 《中国农村水利水电》1993,(5)

取代传统避雷针的一种新型防雷装置——半导体消雷器已经问世。本文根据半导体消雷器的性能特征,以电力系统为应用领域,提出了将半导体消雷器组成联合保护网带的方法,总结了运用半导体消雷器的实际经验。  相似文献   

Gangrenous mastitis in dairy herds     

Power E 《The Veterinary record》2003,153(25):791-792

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Evaluation of tests for anthelmintic resistance in cyathostomes     

Pook JF  Power ML  Sangster NC  Hodgson JL  Hodgson DR 《Veterinary parasitology》2002,106(4):331-343

Resistance, especially to the anthelmintic benzimidazoles (BZ), has been reported in horse cyathostomes world-wide. Diagnosis of resistance has traditionally been made by faecal egg count reduction (FECR) trials, however, this technique has limitations. Some of the shortcomings may be resolved by refining the test or by using an in vitro test. FECR tests and the larval development assay (LDA) were performed on adult horses held on 15 different horse properties across a wide geographical area of NSW, Australia. FECR were measured before and 10-14 after days treatment with oxibendazole (OBZ), morantel (MOR) or ivermectin (IVM) at recommended dose rates. Eight properties were rejected following low pre-treatment egg counts, leaving seven in the study. On these, the majority of larvae recovered from faecal cultures were cyathostomes. Using a definition of resistance as a FECR of <90%, resistance to OBZ was present on six properties and to MOR on two properties. Resistance to IVM was not detected. An alternative method of calculating FECR based on individual horse egg counts pre- and post-treatment was developed and results from the same properties compared with the results of the LDA. For example, for the BZ, correlation coefficients of values of lethal concentration to kill 50% of population (LC50) on LDA and FECR percentages were -0.536 before and -0.704 after OBZ treatment. We conclude that the LDA has the potential to be a single visit test for detection of anthelmintic resistance in horse cyathostomes but requires further investigation and standardisation.  相似文献   

The influence of the lunar cycle on fertility on two Thoroughbred studfarms     

Kollerstrom N  Power C 《Equine veterinary journal》2000,32(1):75-77

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Selection for salt and drought tolerance in protoplast- and explant-derived tissue cultures of Colt cherry (Prunus avium x pseudocerasus)     

Ochatt SJ  Power JB 《Tree physiology》1989,5(2):259-266

Colt cherry (Prunus avium x pseudocerasus) callus cultures were derived from leaf protoplasts, protoplasts of root cell suspension cultures, or by direct culture of leaf and root tissues. Survival of calli cultured on basal proliferation medium containing 25, 50, 100 or 200 mN (millinormal) NaCl, Na(2)SO(4) or KCl, or iso-osmotic (with NaCl) concentrations of mannitol ranged from 1 to 15%. After six transfers on the same medium, surviving cell lines were subjected to three cycles of direct recurrent selection; i.e., in each cycle, they were cultured alternately on basal proliferation medium, and on basal proliferation medium supplemented with NaCl, KCl, Na(2)SO(4) or mannitol. Salt- or mannitol-tolerant cell lines selected in this way had smaller cells than unselected cell lines, and they grew more rapidly and had higher callus and cell survival rates than unselected cell lines when cultured in the presence of salt or mannitol. Cells lines selected for tolerance to one agent (sodium salt, potassium salt or mannitol) showed minimal tolerance to another agent. However, when plants were regenerated from salt- or mannitol-tolerant callus and new cultures derived from them, the new cultures showed tolerance to all of the salts and mannitol. Plant regeneration from the new cultures was not achieved under the conditions that led to the regeneration of the parent plants from callus.  相似文献   

Soil properties and nitrogen availability in silvopastoral plantings of Acacia melanoxylon in North Island, New Zealand     

I.L. Power  B.S. Thorrold  M.R. Balks 《Agroforestry Systems》2003,57(3):225-237

Acacia melanoxylon, a N₂-fixing timber tree occurring naturally in eastern Australia, is now promoted as a component of silvopastoral systems; but the interaction of the tree with pasture and soils has not been adequately studied. This study investigated the effects of Acacia melanoxylon on soil nitrogen (N) levels, N availability, soil pH, bulk density, organic carbon, C:N ratios and soil moisture in three separate silvopastoral sites with contrasting soil types in the North Island of New Zealand. At each site four tree stocking rates were studied (0, 500, 800, and 1700 stems ha^–1). The trees were nine years old at the time of the study. Soil samples from each study site were taken once at three depths (0 to 75 mm, 75 to 150 mm, and 150 to 300 mm), with three replicates per tree stocking rate. Soil analyses showed that although there were differences between soil types, few statistically significant differences occurred due to tree stocking rate. A greenhouse pot trial growing ryegrass (Lolium multiflorum L. cv. Concord) in soil from the A horizon of each soil type from under the trees and the open pasture found that ryegrass yield, N uptake and N supply increased with increasing tree stocking rate. Increased N supply under the trees, coupled with greater soil moisture compared to the open pasture may have accounted for the higher pasture yield under Acacia melanoxylon compared to non dinitrogen fixing tree species. This study suggested that Acacia melanoxylon in a silvopastoral system had the potential to increase soil N availability.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

Use of stable isotopes to distinguish farmed from wild Atlantic salmon, Salmo salar   总被引：2，自引：0，他引：2  

J. B. Dempson  M. Power 《Ecology of Freshwater Fish》2004,13(3):176-184

Abstract –  Stable isotopes of carbon and nitrogen ( δ ¹³C and δ ¹⁵N) were examined in wild and aquaculture origin Atlantic salmon, Salmo salar , to evaluate their utility to identify escaped farmed fish. Samples of muscle tissue obtained from wild Conne River, Newfoundland, salmon were significantly more enriched in nitrogen ( δ ¹⁵N: mean = 12.75; SD ± 0.38‰) but depleted in lipid corrected carbon ( δ ¹³C': mean = −20.51; SD ± 0.23‰) by comparison with aquaculture specimens obtained from Bay d'Espoir, Newfoundland ( δ ¹⁵N = 10.96 ± 0.19‰;  δ ¹³C' = −19.25 ± 0.17‰) resulting in a complete separation of the two groups. Aquaculture specimens differed in δ ¹³C' from analyses of commercial salmon diet by 0.24‰, within the enrichment range associated with trophic transfers, while the δ ¹⁵N values in salmon muscle were enriched by 5.01‰. Although differences occurred in direct comparisons of white muscle and adipose tissue ( N  = 49), the average δ ¹³C' and δ ¹⁵N signatures varied in absolute amounts by only 0.5‰, supporting the use of adipose tissue as a nonlethal means to determine isotopic signatures of Atlantic salmon.  相似文献