RESPONSES OF PLANKTONIC AND BENTHIC COMMUNITIES TO FERTILIZER AND FEED APPLICATIONS IN SHRIMP MARICULTURE PONDS     

John S. Rubright  Jim L. Harrell  Hoyt W. Holcomb  Jack C. Parker 《Journal of the World Aquaculture Society》1981,12(1):281-299

An experiment was performed to evaluate the responses of naturally occurring populations of plankton and benthos to applications of inorganic fertilizer and commercial marine ration in a shrimp grow-out facility near Angleton, Texas. Ten ponds were stocked with an average of 17,000 post-larval Penaeus stylirostris on July 8, 1980. Three of these ponds received fertilizer 19 days before stocking and again 7 days after stocking. Another 3 ponds were fed daily with Ralston Purina Experimental Marine Ration 20 beginning on the stocking day. Three other ponds received the 2 fertilizer applications and daily feed. One control pond was not given fertilizer or feed. Beginning 19 days before stocking and continuing for 14 weeks, samples were collected and quantitatively analyzed for chlorophyll, zoo-plankton and benthic organisms. Results indicated that fertilizer stimulates the production of chlorophyll and planktonic copepods. Planktonic rotifers varied independently of feed or fertilizer. Densities of planktonic polychaete larvae seemed to be related to changes in the populations of benthic adult polychaetes. The benthic community was dominated by polychaetes, harpacticoid copepods and nematodes. Polychaetes tended to be more abundant when feed was present. Harpacticoids and nematodes did not seem to be affected by experimental treatments. All benthos fell to very low densities after 50 days of the study. The best shrimp production occurred in feed and fertilized ponds, followed by feed only, fertilizer only and the control. Potential linkages between natural production and shrimp growth are discussed.  相似文献   

Encephalomyocarditis virus infection in alpacas     

TW O'Connor  DS Finlaison  LK Manning  MS Hazelton  ZB Spiers  P Pinczowski  EM Bolin  PD Kemsley  NU Horadagoda  AJ Dart  RW Cook  PD Kirkland 《Australian veterinary journal》2020,98(10):486-490

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Simultaneous Measurement of Local Gain and Electron Density in X-ray Lasers     

R Cauble  Da Silva LB  TW Barbee  P Celliers  C Decker  RA London  JC Moreno  JE Trebes  AS Wan  F Weber 《Science (New York, N.Y.)》1996,273(5278):1093-1096

X-ray lasers (XRLs) have experimental average gains that are significantly less than calculated values and a persistently low level of spatial coherence. An XRL has been used both as an injected signal to a short XRL amplifier and as an interferometer beam to measure two-dimensional local gain and density profiles of the XRL plasma with a resolution near 1 micrometer. The measured local gain is in agreement with atomic models but is unexpectedly spatially inhomogeneous. This inhomogeneity is responsible for the low level of spatial coherence observed and helps explain the disparity between observed and simulated gains.  相似文献   

DNA-functionalized nanotube membranes with single-base mismatch selectivity     

Kohli P  Harrell CC  Cao Z  Gasparac R  Tan W  Martin CR 《Science (New York, N.Y.)》2004,305(5686):984-986

We describe synthetic membranes in which the molecular recognition chemistry used to accomplish selective permeation is DNA hybridization. These membranes contain template-synthesized gold nanotubes with inside diameters of 12 nanometers, and a "transporter" DNA-hairpin molecule is attached to the inside walls of these nanotubes. These DNA-functionalized nanotube membranes selectively recognize and transport the DNA strand that is complementary to the transporter strand, relative to DNA strands that are not complementary to the transporter. Under optimal conditions, single-base mismatch transport selectivity can be obtained.  相似文献   

Humoral factors important in resistance of salmonid fish to bacterial disease. I. Serum antibody protection of rainbow trout (Salmo gairdneri) against vibriosis     

Lee W. Harrell  Howard M. Etlinger  Harold O. Hodgins 《Aquaculture (Amsterdam, Netherlands)》1975,6(3):211-219

Serum antibody is shown by passive immunization and absorption experiments to be an important component of defense mechanisms against experimentally induced vibriosis in rainbow trout (Salmo gairdneri). Antigen from heat-killed Vibrio anguillarum injected into trout with Freund's complete adjuvant induced much higher agglutinin titers than formalin-killed bacteria with or without adjuvant, or heat-killed bacteria without adjuvant. Passively transferred trout anti-Vibrio anguillarum serum provided protection against experimental vibriosis in trout for more than 2 months. Passively transferred anti-Vibrio anguillarum rabbit serum also protected trout.  相似文献   

Pigs weaned from the sow at 10 days of age respond to dietary energy source of manufactured liquid diets and exogenous porcine somatotropin     

Oliver WT  Touchette KJ  Coalson JA  Whisnant CS  Brown JA  Oliver SA  Odle J  Harrell RJ 《Journal of animal science》2005,83(5):1002-1009

Previous research indicates that the neonatal pig does not alter feed intake in response to changes in the energy density of manufactured liquid diets. Also, the limited response of IGF-I to exogenous porcine ST (pST) previously observed in young pigs may be influenced by the source of dietary energy. Our objectives were to 1) determine the effect of a high-fat (HF; 25% fat and 4,639 kcal/kg ME; DM basis) or low-fat (LF; 2% fat and 3,481 kcal/kg ME; DM basis) manufactured liquid diet on pig performance; and 2) determine whether the limited response to exogenous pST in young pigs depends on the source of dietary energy. Two replicates of 60 pigs (n = 120; barrows and gilts distributed evenly), with an initial BW of 4,207 +/- 51 g, were weaned from the sow at 10 d of age and used in a randomized complete block design. Pigs were assigned by BW to one of six pens. Diets were formulated to provide a constant lysine:ME ratio and were fed on a pen basis for a duration of 9 d. On d 5, barrows and gilts within a pen were assigned randomly to receive either 0 or 120 microg of pST.kg BW(-1).d(-1) for 4 d. Pigs gained 336 +/- 9 g/d, which resulted in an ending BW of 7,228 +/- 120 g, regardless of dietary treatment (P > 0.15). Pigs fed the LF diet consumed 17% more DM per pen daily than pigs fed the HF diet (2,777 +/- 67 vs. 2,376 +/- 67 g/d, P < 0.01), but calculated ME intake did not differ between dietary treatments (P > 0.20). The G:F was 24% greater in HF- than in LF-fed pigs (P < 0.01). Plasma urea N concentrations were higher in the HF-fed pigs (11.0 +/- 0.6 mg/dL) than in pigs fed the LF diet (6.2 +/- 0.6 mg/dL; P < 0.05). Treatment with pST increased circulating IGF-I (P < 0.01) and decreased PUN (P < 0.01) concentration 32 and 25%, respectively, regardless of dietary treatment (P > 0.30). Circulating leptin averaged 1.8 +/- 0.1 ng/mL and was not affected by dietary treatment (P > 0.35) or pST (P > 0.40). These results suggest that the ST/IGF axis is responsive in the young pig and the increase in circulating IGF-I and growth is independent of the source of dietary energy. Also, young pigs respond to a lower energy density liquid diet with increased feed intake, without altering growth performance, apparently utilizing a mechanism other than circulating leptin.  相似文献   

Pasteurella anatipestifer as a cause of mortality in semiwild pen-raised mallard ducks in South Carolina     

T H Eleazer  H G Blalock  J S Harrell  W T Derieux 《Avian diseases》1973,17(4):855-857

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Characterization and Liming Effect of Wood Ash Generated from a Biomass-Fueled Commercial Power Plant     

Nutifafa Adotey  Dustin L. Harrell  Wayne P. Weatherford 《Communications in Soil Science and Plant Analysis》2018,49(1):38-49

Laboratory and greenhouse experiments were carried out to characterize and examine wood ash from a biomass-fueled commercial power plant as a lime. Experimental treatments include wood ash and two commercial limes applied at six application rates. The effective calcium carbonate equivalence (ECCE) of wood ash ranged from 22 to 49%. Wood ash increased soil pH by 0.31–3.18 over unlimed soils, and these changes in pH were similar to the effect of commercial limes. The soil pH at three weeks after wood ash application was constant through week seventeen. Wood ash increased electrical conductivity by 0.13–0.63 dS m^?1 compared to unlimed soils at three weeks after liming; however, a 39–69% decreased was observed by week seventeen. Common bermudagrass did not respond to the application of wood ash and commercial limes. The results of this study suggest that wood ash from the biomass-fueled commercial power plant with low ECCE could be a liming material.  相似文献   

Determination of Critical Soil Silicon Levels for Rice Production in Louisiana Using Different Extraction Procedures     

Wooiklee Paye  Dustin Harrell  Tapasya Babu  Yumiko Kanke  Lawrence Datnoff 《Communications in Soil Science and Plant Analysis》2018,49(17):2091-2102

While silicon (Si) fertilization is widely practiced in rice production, establishing critical soil Si levels has remained understudied. Field trials were established at 12 sites across Louisiana from 2013 to 2015 to determine critical soil Si for rice cultivation. Five silica slag (14% Si) rates at 0, 1, 2, 4, 6, and 8 Mg ha^?1 and two lime rates (2 and 4 Mg ha^?1) were arranged in randomized complete block design with four replications. Post harvest soil samples were analyzed for Si using seven extraction procedures. The critical soil Si levels established by the linear plateau model using 0.5 M acetic acid-1 hr (OAc-1) extraction procedure were 36, 41 and 50 mg kg^?1 for plant Si uptake, grain yield, and relative yield as response variables, respectively. Generally, soils having high initial Si and pH had minimal responses to Si fertilization, whereas Si content of soils with low initial Si was significantly increased.  相似文献   

Influences of trees on abundance of natural enemies of insect pests: a review     

M. E. Dix  R. J. Johnson  M. O. Harrell  R. M. Case  R. J. Wright  L. Hodges  J. R. Brandle  M. M. Schoeneberger  N. J. Sunderman  R. L. Fitzmaurice  L. J. Young  K. G. Hubbard 《Agroforestry Systems》1995,29(3):303-311

In this article we review the use of natural enemies in crop pest management and describe research needed to better meet information needs for practical applications. Endemic natural enemies (predators and parasites) offer a potential but understudied approach to controlling insect pests in agricultural systems. With the current high interest in environmental stewardship, such an approach has special appeal as a method to reduce the need for pesticides while maintaining agricultural profitability. Habitat for sustaining populations of natural enemies occurs primarily at field edges where crops and edge vegetation meet. Conservation and enhancement of natural enemies might include manipulation of plant species and plant arrangement, particularly at these edges; and consideration of optimum field sizes, number of edges, and management practices in and near edges. Blending the benefits of agricultural and forestry (windbreak) systems is one promising approach to field edge management that has additional benefits of wind protection and conservation of desirable wildlife species.Journal series 10549 of the Agriculture Research Division, University of Nebraska-Lincoln. This material was prepared with the support of USDA Agreement 91-COOP-1-6592 for the USDA/EPA Program, Agriculture in Concert with the Environment. Any opinions, findings, conclusions or recommendations expressed herein do not necessarily reflect the views of the US Department of Agriculture or the US Environmental Protection Agency.  相似文献