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141.
Heritabilities of size traits and growth rate traits, as well as genetic, phenotypic and environmental correlations were estimated at three ages for a captive population of Pacific white shrimp (Penaeus vannamei) grown indoors. A covariate, mean size or mean growth rate during early growth in individual tanks before tagging and mixing, was introduced in the analyses to reduce the error caused by unique previous growth conditions on variance components. Heritabilities of size traits increased with age, with the h2 for TL, AL, TWt and Wi1AS being 0.15, 0.20, 0.20 and 0.22, respectively, at 17 weeks, increasing to 0.28, 0.33, 0.34 and 0.35 at 29 weeks of age. Heritabilities of growth rate traits estimated between consecutive growth periods decreased from the first (h2 for ΔTL 0.65, ΔAL 0.71, ΔTWt 0.63 and ΔWi1AS 0.84) to the second period (h2 for ΔTL 0.34, ΔAL 0.50, ΔTWt 0.54 and ΔWi1AS 0.52). Phenotypic correlations were always larger than genetic correlations for both, size and growth rate traits. Genetic correlations between size traits within age were high (rG >0.95), but those between the same size trait at different ages decreased as the age difference increased in spite of a consistently high environmental correlation (rE 0.80–0.85) between the same trait at different ages. Phenotypic and genetic correlation's between the same growth rate trait at the two different growth periods evaluated were negative or zero (rG TL –0.26, AL –0.24, Wi1AS 0.00) with the exception of total weight (rG TW 0.35) and the environmental correlations between growth periods were also low (rE 0.13–0.32).  相似文献   
142.
ABSTRACT:   Sea water environmental conditions over annual cycles were investigated and compared between two oyster farming areas, western Hiroshima Bay and Oginohama Bay (a branch of Ishinomaki Bay) in Miyagi Prefecture, to appropriately manage oyster culture or more efficiently utilize farming areas. The environmental parameters of temperature, salinity, nutrient concentrations (NO2–N, NO3–N, NH4–N, PO4–P, and SiO2–Si) and size-fractionated chlorophyll- a (<0.2, 2–20, >20µm), and abundances of microzooplankton were measured in each bay at the surface, and 2 and 5 m depth layers. Differences in the annual mean values and results with monthly paired Student's t -tests showed that salinity was lower, and temperature, nutrient (especially PO4–P) and chlorophyll- a concentrations, and abundance of microzooplankton, were higher in Hiroshima Bay than in Oginohama Bay. Differences in environmental conditions between inshore and offshore areas of each bay suggest that inflows of river water in western Hiroshima Bay and sea water from offshore had the most significant effects on the environmental conditions. It is concluded that such oceanographic and biological differences strongly affect the oyster farming system, especially regarding the optimum usage of offshore areas in Summer under clean, cold and stable seawater conditions, rather than food quantity in Hiroshima Bay, and under more abundant food conditions in Oginohama Bay.  相似文献   
143.
  1. Fish assemblages in dryland rivers have life-history strategies that have evolved in response to environmental conditions and triggers, particularly water temperatures and flow regimes. The regulation of rivers through the construction of dams, weirs and other water diversion structures has altered natural flow regimes and the associated ecological processes of river systems worldwide.
  2. Over a 3-year period, using standardized fish sampling and daily otolith ageing, the recruitment of eight freshwater fish species was monitored in response to various abiotic drivers, including hydrology and water temperatures, throughout the Macquarie River, a large regulated river system of the Australian Murray-Darling Basin.
  3. A data-driven statistical classification system is provided that groups species into reproductive guilds, based on their recruitment response to hydrology and water temperature, specifically designed for use in environmental flow management.
  4. The eight species were grouped into three distinct reproductive guilds that showed similar recruitment responses to the abiotic drivers. Murray-Darling rainbowfish, Murray cod, and eel-tailed catfish were considered as a single guild, characterized by seasonal recruitment during a relatively narrow thermal window under low to moderate stable discharges. The second group included common carp, bony herring, and golden perch, which recruited primarily in association with larger flow events. Un-specked hardyhead and Australian smelt formed a more differentiated guild, recruiting over a broad range of temperatures and discharges. Limitations associated with using a reproductive guild approach to simplify water management are discussed.
  5. This study highlighted important relationships among hydrology, water temperatures, and successful recruitment that can, in turn, be used to inform development of adaptive flow management plans and effective use of environmental water for the conservation management of native fish communities. Important considerations in the design of studies that aim to examine relationships between recruitment and abiotic drivers are also discussed.
  相似文献   
144.
Foreign direct investment (FDI) inflows have been significantly impacted by environmental regulation (ER). This study is aiming at analyzing the ER effect on the FDI inflows. By using the data of 2008–2018, we use Three-stages least square (3SLS) method to assess the connection between FDI inflows and ER. The study results reveal that in Chinese industries, technological innovation (TI) is stipulated by the ER, and as a result, FDI has been engrossed. The results further reveal that TI has been enhanced by capital penetration, and a positive effect is perceived between TI and FDI. The findings of our study also show that there is a significant association between foreign capital (FC) inflows and TI, which indicates that technological policies are effective and advanced environmental policies would intensify the relevant policies between firms. Based on the study outcomes, this research proposes some policy suggestions for constructing a attuned policy system of environmental protection and FDI by regulating the implementation of conforming strategies.  相似文献   
145.
从地理位置、水质及沉积物、红树林、珊瑚礁海岸等方面介绍亚龙湾生态自然环境特点,分析其生态旅游发展现状、形式及成效,提出对亚龙湾生态环境保护的建议。  相似文献   
146.
SUMMARY: Effects of temperature, irradiation, salinity and inorganic nitrogen concentration on two cultured strains of zooxanthellae isolated from the corals Pocillopora damicornis (strain P) and Montipora verrucosa (strain M) were studied. Each strain showed different growth responses in terms of temperature and light intensity. A maximum growth rate of strain P, 1.2 per day, was observed at 32°C under all light intensities examined (5–40 μEm−2s−1). However, its photosystem 2 activity (FRI) was higher at 28°C than at 32°C under most light intensities. In contrast, the growth rate of strain M was affected more by light intensity and was almost invariably affected at all temperatures examined (24–36°C). Both algal strains had a comparable growth rate and FRI at salinities from 20 to 35 PSU under moderate temperature and irradiant conditions. High temperature and low irradiation reduced the algal tolerance against low salinity. The gross photosynthesis per cell was not affected by the ammonium enrichment more than 5 μM per day although the cellular chlorophyll a content and cell density increased in proportion with the ammonium enrichment up to 20 μM per day. A potential response of zooxanthellae to the multiple environmental stresses was shown from these results.  相似文献   
147.
辽南滨海黄土的粒度分维值及其环境意义   总被引:1,自引:0,他引:1  
以Mastersizer2000激光粒度仪测出的粒度数据为基础,应用分形理论计算得出:七顶山马兰黄土的粒度分维值介于2.2085~2.3184之间,平均值为2.2744,相关系数为0.8835;离石黄土粒度分维值介于2.2748~2.4237之间,平均值为2.3467,相关系数为0.8920。全剖面粒度分维值在2.2085~2.4237之间,平均值为2.3187,相关系数达0.88以上,粒度分布具有分形特征(0.76μm~263.75μm的标度范围内)。分维值的大小对黄土的形成环境有良好的指示意义。本区马兰黄土比离石黄土的分维值低,说明马兰黄土沉积时东亚冬季风强盛,气候寒冷干燥,次生成壤作用弱,分选系数偏小,分选性比离石黄土稍好,自组织程度低,分维值偏低且变化幅度小;离石黄土沉积时夏季风较冬季风强盛,气候温暖湿润,后期的成壤改造作用强,分选较差,分选系数稍大,自组织程度高,分维值偏高且变化幅度大。经对比分析得出:粒度分维值反映的环境演变与磁化率、粒度所反映的环境演变一致。  相似文献   
148.
为有效保护北京市昆虫多样性,在调查和收集整理北京市昆虫物种分布名录的基础上,基于区级尺度研究北京市昆虫分布格局,通过回归模型和多层次方差分解等方法探讨昆虫丰富度与环境因子的关系。结果显示,北京市昆虫物种有29目409科5 259种,其中门头沟区昆虫物种数最多,为18目243科2 232种,东城区昆虫物种数最少,为8目34科68种,表现为山区昆虫多样性明显高于平原区和城区。影响昆虫科丰富度的主要因素为最高月降水量、森林覆盖率和昼夜温差月平均值;影响昆虫种丰富度的主要因素为路网密度、最高月降水量、昼夜温差月平均值和年平均气温。不论是在昆虫科或种阶元上,最高月降水量和昼夜温差月平均值对昆虫丰富度的解释能力最显著,说明降水和温度因子对昆虫分布有强限制性。表明昆虫丰富度及其分布格局是由不同环境因子共同作用的结果,降水和温度的变化对北京市昆虫丰富度有决定性的影响。  相似文献   
149.
150.
环境标志是以市场为介质,自愿性的以环境保护为最终目的的环境管理模式。环境标志法律制度不仅是规范环境标志及其计划的规则,规则的功能实现及良好运作也是环境标志法律制度所应考察之意。环境标志的法律属性是证明商标;环境标志使用合同是民事合同,而非行政合同。环境标志认证制度与使用制度是环境标志制度最基本的两个方面,需完善其规范构成和运行。建立完善的环境标志法律规则及确保其良好的运行及功能的实现是环境标志法律制度健全的主要内容。  相似文献   
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