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121.
Observations on growth, sexual maturity and spawning performance of pond-reared Penaeus merguiensis 总被引:2,自引:0,他引:2
This 12‐month preliminary study investigated the development of sexual characters, primary sexual maturity, ovarian maturity and spawning performance of pond‐reared Penaeus merguiensis in relation to culture conditions in south‐east Queensland, Australia. Post‐larvae of P. merguiensis were produced and cultured in two 60‐m3 tanks during the first 14 weeks. Before winter, they were harvested and stocked in three different overwintering facilities: a 200‐m2 covered pond, two 60‐m3 outdoor tanks and a 15‐m3 indoor, recirculated tank at a stocking density of 10 individuals m?2. The development of sexual characters was found to be similar to that reported previously in wild P. merguiensis. Males matured at younger ages and smaller sizes than females. Overall, the average size at primary sexual maturity of pond‐reared P. merguiensis was 23.1 mm carapace length for males (possessed spermatophores) and 29.3 mm for females (being impregnated). Water temperature and the availability of natural food strongly influenced prawn growth, maturity rate and their subsequent spawning performance. Growth, maturity rate and spawning performance of prawns in the covered pond were significantly higher than in the other overwintering facilities. Prawns started mating at 6–7 months, reached full ovarian maturation and spawned as early as about 8 (peaked at 9–11) months from hatching, producing high fecundity and viable larvae. There was a strong relationship (P < 0.001) between prawn size and fecundity. The results of this study suggest a potential for using pond‐reared broodstock P. merguiensis for hatchery production and for domestication or selective breeding programmes. 相似文献
122.
Canopy cover (CC) is a good predictor variable for plant growth parameters such as leaf area index and aboveground biomass.
A nondestructive, low-cost, and convenient method is presented for estimating CC using digital camera image analysis. CC was
estimated by the ratio of plant pixels to total pixels of digital camera image of rice field. To determine the criteria for
segmenting the rice plant from variable soil background, three mosaic images for rice plant, flooded/bare soil, and algae-infested
background were prepared from digital camera images that were taken in various field conditions. An image analysis program
was developed in Visual Basic to extract red, green, and blue (RGB) features from the mosaic images, calculate RGB-based color
indices, and compute the minimum segmentation error for separating rice plant from background. When judged by the segmentation
error, modified excessive green index (MEGI) showed the highest potential for segmenting rice plant from flooded/bare soil
background, followed by normalized green (g) and excessive green index (EGI). At the threshold MEGI value of 0.03, the segmentation
error was the lowest as 0.13%. Any single index considered was not satisfactory in segmenting rice plant from algae-infested
background. However, a discriminant function of 1.2553EGI + 0.01735G − 0.01474B was successful in segmenting rice plant from
flooded/bare soil and algaeinfested background with segmentation errors of 0.34 and 1.17%, respectively. CC for four rice
varieties from tillering to booting stage was estimated based on the threshold value of MEGI and discriminant function and
also manually using commercial software. Both estimates of CC showed good relationship of r2 = 0.94, suggesting that a digital camera could be used efficiently for measuring the CC of rice field. 相似文献
123.
Narongrit Sombatsompop Nongyao Premkamolnetr Teerasak Markpin Santi Ittiritmeechai Chatree Wongkaew Wutthisit Yochai Preeyanuch Ratchatahirun Lee Inn Beng 《Asia Pacific viewpoint》2011,52(2):207-218
This opinion article expresses two key viewpoints regarding the options for Association of South‐East Asian Nations (ASEAN) universities in pursuit of fulfilling the demand for greater research visibility and academic reputation. The first viewpoint outlines the importance of promoting research collaboration among ASEAN researchers and their international peers in increasing the visibility and impact of ASEAN research. The second viewpoint examines the ASEAN research characteristics, the challenges and existing best practices of its journal publishing landscape, the potential role of non‐ASEAN international journals in improving the profile of ASEAN research and explores the needs and benefits of establishing an ASEAN Integrated Journal Publishing Network (IJPN). It is through these combined approaches, we believe, that effective policy change, the standardisation of publishing structure, procedures, and systems to drive journal development, improvement of journal quality, and establishment of a consistent framework for measuring researcher performance will result. This article also includes a proposal for the IJPN structure and implementation plan, and highlights the key benefits of taking a collaborative approach to achieving this common goal. 相似文献
124.
Kwangho Choi Chung Il Lee Kwangseok Hwang Sang-Woo Kim Jong-Hwa Park Yeong Gong 《Fisheries Research》2008,91(2-3):281-290
Data on squid catches of Korean and Japan, water temperatures at depth of 100 m, and night-visible images of fishing boats collected in the East (Japan) Sea from 1970 to 1999 were analyzed to examine the distribution and migration of the Japanese common squid, Todarodes pacificus, in the southwestern part of the East (Japan) Sea. The main fishing grounds detected from squid catch in each grid (0.5° latitude × 0.5° longitude) by Korean squid fishery and night-visible images provided by the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) were situated in the southwestern part of the East (Japan) Sea. The distribution and migration route was illustrated from squid catch in each grid and DMSP OLS image. In years of high catches, the fishing grounds were situated mainly between Ulleung Island and the eastern coastal waters of Korea, while in years of low catches they were situated between Ulleung Island and the Yamato Bank in the central East (Japan) Sea. The center of fishing activity began moving northward from around the Korea/Tsushima strait to the northern boundary of the Tsushima Warm Current in March, reaching into the Yamato Bank in September, and then returning to the strait by February. The northward and southward migration routes differed; the northward migration route occurred closer to the mainland coast of Korea than the southward migration route did. This work suggests T. pacificus begin their northward migration almost 2 months earlier than previously suggested. 相似文献
125.
Kim Soon-Oh Jeong Jin Young Lee Woo-Chun Yun Seong-Taek Jo Ho Young 《Journal of Soils and Sediments》2021,21(8):2755-2769
Journal of Soils and Sediments - Electrokinetic (EK) soil remediation is significantly affected by the electrode configurations. Therefore, this study was conducted to compare the performance of... 相似文献
126.
In this study, changes in total factor productivity of 12 Korean offshore fisheries between 1997 and 2009 were estimated through
the Malmquist productivity index, which is a nonparametric method. Also, the cause of such changes in productivity of each
fishery was analyzed more specifically by segmenting into factors for technological progress and technical efficiency. As
a result of this analysis, the total factor productivity change of the entire offshore fisheries was −6.0 %. Changes in the
technical efficiency and technological level factors, respectively, contributed 0.2 and −6.2 % to this rate of decrease in
total factor productivity; that is, inactivity of technological progress led to the decrease in productivity of the offshore
fisheries. In addition, technological progress and technical efficiency were found to differently influence the change in
total factor productivity of each fishery. In order for each fishery to improve productivity, better rational fisheries management
policies by the government and efforts by the fishing industry and individual fishing business units must accompany factors
that promote productivity increase. 相似文献
127.
Jie-Min Lee Tsorng C. Hwang 《Aquaculture Economics & Management (Blackwell Science)》2013,17(1):47-57
ABSTRACT Policy decisions on what aquaculture products to develop require information on consumer demand for cultured species. However, information on the structure of demand for aquaculture products is limited and what few studies there are in Taiwan, where aquaculture is a major industry, suffer from methodological problems. To clear up some of these problems, we used modified nonnested testing techniques and performance forecasting to determine which generalized models could best estimate the demand for Taiwanese aquaculture products. The results of modified nonnested testing of the aquaculture demand system showed that prices predetermined and quantities predetermined could be used to estimate demand. The generalized ordinary demand model was able to better forecast performance than the generalized inverse demand model. We used the likelihood ratio test to discriminate among the four competing models for the generalized ordinary model; the AIDS model could be more suitably applied to the data. A more general model that is able to incorporate different dynamic structures (partial adjustment, first autoregressive, and static). This general framework is applied to the AIDS model. The first autoregressive AIDS model we used to calculate the own and cross-price elasticities for milkfish, tilapia, shrimp, shellfish, and carps found that price elasticities varied across fish type, that some products had high long-run own price elasticities, and that the demand for aquaculture products was largely determined by inertia. 相似文献
128.
Nanominerals, mineral nanoparticles, and Earth systems 总被引:4,自引:0,他引:4
Hochella MF Lower SK Maurice PA Penn RL Sahai N Sparks DL Twining BS 《Science (New York, N.Y.)》2008,319(5870):1631-1635
Minerals are more complex than previously thought because of the discovery that their chemical properties vary as a function of particle size when smaller, in at least one dimension, than a few nanometers, to perhaps as much as several tens of nanometers. These variations are most likely due, at least in part, to differences in surface and near-surface atomic structure, as well as crystal shape and surface topography as a function of size in this smallest of size regimes. It has now been established that these variations may make a difference in important geochemical and biogeochemical reactions and kinetics. This recognition is broadening and enriching our view of how minerals influence the hydrosphere, pedosphere, biosphere, and atmosphere. 相似文献
129.
Chen ZY Jing D Bath KG Ieraci A Khan T Siao CJ Herrera DG Toth M Yang C McEwen BS Hempstead BL Lee FS 《Science (New York, N.Y.)》2006,314(5796):140-143
A common single-nucleotide polymorphism in the brain-derived neurotrophic factor (BDNF) gene, a methionine (Met) substitution for valine (Val) at codon 66 (Val66Met), is associated with alterations in brain anatomy and memory, but its relevance to clinical disorders is unclear. We generated a variant BDNF mouse (BDNF(Met/Met)) that reproduces the phenotypic hallmarks in humans with the variant allele. BDNF(Met) was expressed in brain at normal levels, but its secretion from neurons was defective. When placed in stressful settings, BDNF(Met/Met) mice exhibited increased anxiety-related behaviors that were not normalized by the antidepressant, fluoxetine. A variant BDNF may thus play a key role in genetic predispositions to anxiety and depressive disorders. 相似文献
130.
Jianzhong?ChengEmail authorView authors OrcID profile Yunlong?Li Weichang?Gao Yi?Chen Wenjie?Pan Xinqing?Lee Yuan?Tang 《Biology and Fertility of Soils》2018,54(3):373-383
An experiment was conducted with tobacco (Nicotiana tabacum L.) grown in a Cd- and Pb-contaminated calcareous soil amended with 0.0, 1.0, 2.5, and 5.0% (w/w) tobacco stalk biochar (BC). The BC amendment significantly increased organic matter, total C, N, P, and K contents of soil, and the C/N ratio. Bioavailable metal concentrations (DTPA extraction) decreased by increasing BC application rate. The 5.0% BC amendment significantly decreased the DTPA-extractable Cd and Pb by 10.4 and 13.6%, respectively. Correspondingly, the bioaccumulation and translocation factors of Cd and Pb also decreased by increasing the BC addition rates and this indicated that BC inhibited the uptake and transfer of both Cd and Pb by tobacco plants. Moreover, high-throughput sequencing revealed that BC increased Chao1 richness, Shannon’s diversity and Simpson’s diversity of bacterial communities of soil. The relative abundance and genera composition of Adhaeribacter, Rhodoplanes, Pseudoxanthomonas, and Candidatus Xiphinematobacter increased under BC treatments, while those of Kaistobacter, Lacibacter, and Pirellula decreased. Overall, BC increased soil nutrients (C, N, P, and K contents), enhanced bacterial diversity indexes and richness, and changed the bacterial community composition, which may all have contributed to reduce the mobility and bioavailability of both Cd and Pb in a calcareous soil. 相似文献