Behavioural responses of eel (Anguilla anguilla) approaching a large pumping station with trash rack using an acoustic camera (DIDSON)     

Olvin Alior van Keeken  Ralf van Hal  Hendrik Volken Winter  Ingrid Tulp  Arie Benjamin Griffioen 《Fisheries Management and Ecology》2020,27(5):464-471

European eel, Anguilla anguilla L., migrating to the sea encounter many man‐made structures that can hamper and delay migration or induce mortality. Studying small‐scale behavioural movements in front of these man‐made structures could provide insight in further mitigating adverse effects. The behaviour of eel approaching a trash rack in front of a large pumping station was investigated using a dual‐frequency identification sonar (DIDSON). Eels approaching the trash rack swam through the rack (40.5%) but also showed turning behaviour at (44.7%) or in front of the rack (14.7%). Eels approaching the rack had varying body positions, predominantly head or tail first, but also curled up into a ball or drifted sideways. After turning in front or at the trash rack, eels showed upstream and downwards swimming towards the canal bottom. The results suggest a stepwise response to potential cues, when firstly the body position is changed in such a way that secondly, later on, enhances eventual fast upstream escapement when perceived necessary. Implications for management of these behavioural observations are discussed.  相似文献   

Biodiversity effects on soil processes explained by interspecific functional dissimilarity     

Heemsbergen DA  Berg MP  Loreau M  van Hal JR  Faber JH  Verhoef HA 《Science (New York, N.Y.)》2004,306(5698):1019-1020

The loss of biodiversity can have significant impacts on ecosystem functioning, but the mechanisms involved lack empirical confirmation. Using soil microcosms, we show experimentally that functional dissimilarity among detritivorous species, not species number, drives community compositional effects on leaf litter mass loss and soil respiration, two key soil ecosystem processes. These experiments confirm theoretical predictions that biodiversity effects on ecosystem functioning can be predicted by the degree of functional differences among species.  相似文献   

Community Structure and Fishery Management: a New Zealand Case Study     

Hal B. Levine  Marlene W. Levine 《Asia Pacific viewpoint》1983,24(1):50-68

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A comparison of the effects of the nematodes Radopholus similis and Pratylenchus goodeyi on growth,root health and yield of an East African highland cooking banana (Musa AAA-group)     

Hal Talwana  PR Speijer  CS Gold  RL Swennen  D De Waele 《国际虫害防治杂志》2013,59(3):199-204

We combined two protein-marking enzyme-linked immunosorbent assays (ELISA) with a predator gut content ELISA to monitor the movement and feeding activity of commercially-purchased Hippodamia convergens Guèrin-Mèneville (Coleoptera: Coccinellidae) under realistic field conditions during two field seasons in central Arizona. The protein-marking ELISAs were used to differentiate released H. convergens from the native beetles. Commercially purchased beetles marked with rabbit immunoglobulin G (IgG) were released into cotton fields and chicken IgG marked beetles were released into adjacent cantaloupe fields. Results showed that the total native beetle abundance in each crop was about the same size. The recovery rates after 15 days for the released beetles were less than 1.0% over all the releases, indicating that they dispersed readily from the release site. Of the recaptured beetles containing rabbit IgG (cotton), 82.2% were recovered in cotton and 11.8% moved to cantaloupe. Of those containing chicken IgG (cantaloupe), 66.5% were recovered in cantaloupe and 33.5% moved to cotton. A predator gut content ELISA was used to determine if there were differences in the frequency of predation of released versus indigenous H. convergens on the silverleaf whitefly, Bemisia argentifolii Bellows &; Perring (Homoptera: Aleyrodidae). The proportion of beetles containing whitefly antigens was always higher for the released beetles than for their native counterparts. Our results demonstrate an approach to combine protein marking and predator gut content ELISAs that allows the simultaneous comparison of feeding and intercrop movement of native and commercially-obtained biological control agents.  相似文献   

Inferences for genotyping error rate in ancestry identification from simple sequence repeat marker profiles     

Hongmei Zhang  Hal Stern 《Journal of Agricultural, Biological & Environmental Statistics》2009,14(2):170-187

Genotyping errors can cause difficulties in a variety of scientific analyses including enetic mapping of diseases, ancestry identification, and gene environment interaction etection. This work develops maximum likelihood approaches to estimating genotyping rror rates in the context of calculating ancestry probabilities from simple sequence epeat (SSR) marker profiles. The likelihood function is based on the probabilities for bserved alleles at each marker locus given ancestral genetic profiles. Simulations are sed to demonstrate and evaluate the likelihood approach to inferences. Simulation results ndicate that the quality of inferences is impacted by the relationship (parents or randparents) of the closest ancestors. We apply the methods to a data set of maize SR marker profiles provided by Pioneer Hi-Bred International, Inc. where the results ndicate a low error rate.  相似文献   

Immune response in mice infected by Encephalitozoon cuniculi and suppressed by dexamethasone     

Valencáková A  Halánová M  Bálent P  Dvoroznáková E  Jamborová E  Lesník F  Neuschl J  Páleník L  Cisláková L 《Acta veterinaria Hungarica》2004,52(1):61-69

Several indicators of immune response were observed in immunocompetent mice of the ICR line and those suppressed by dexamethasone upon their experimental infection with the microsporidia of Encephalitozoon cuniculi. The mice were infected by one-shot intraperitoneal administration of 5 x 10(7) pathogenic spores. On Days 7, 14, 28 and 42 after infection, peripheral blood leukocyte phagocytic activity was determined and compared, including phagocytic index and the blastogenic response in spleen cells to mitogenic activation by concanavalin A and phytohaemagglutinin. The results point to the fact that E. cuniculi itself can cause a significant decrease in phagocytic activity of phagocytic leukocytes in the early stages of infection as well as a remarkable decrease in the proliferative response of spleen cells to T-cellular mitogens.  相似文献   

不同种植密度对杂交抗虫棉生长发育及产量构成的影响   总被引：5，自引：0，他引：5  

王海洋  陈建平  蔡立旺  王为  王永慧  戚永奎  施庆华  潘宗瑾  高进 《江西农业学报》2014,(9):27-30

通过田间试验研究了不同种植密度(1.8万~5.4万株/hm2)对抗虫杂交棉中棉所75生长发育、产量及产量构成因素的影响。结果表明:随着种植密度的增大,棉花的全生育期会略缩短,株高先降低然后略增高,单株干物重、总果节数和单株果枝台数均减少,而单位面积总干物重却增加;随着密度的增大,棉株成铃向上部、向内围集中,而且单株成铃数明显减少,铃重、单位面积总铃数和单位面积籽棉产量均呈先增加后减少的趋势,而霜前花率则呈上升的趋势;最适宜的种植密度为3.6万株/hm2,此时籽棉产量最高,达4292.0 kg/hm2。  相似文献