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101.
The hypothesis that the presence of fish farming zones affects the water quality and plankton communities was investigated in an Aegean Sea fish farm during February, June, September and January 2000–2001. In the spatial coverage, a total of 12 stations were sampled; three of them were reference stations. A variance analysis was applied to the measurements made at the stations near the fish farms and at the control stations. While no significant differences in concentrations of nutrients, chlorophyll a, particulate organic carbon and particulate organic nitrogen were detected between the stations and the control sites within one season, significant differences were detected between the parameter values measured except for total dissolved phosphorus and dissolved organic phosphorus at different seasons. The seasonal differences were also significant with regard to the biodiversity. Together with these temporal differences in general, there was a higher diversity of species at the control site as compared with the other stations in September, which was the key season to detection of significant changes. The most important consideration is that it is not sufficient to take the instantaneous values for the physico‐chemical variables; rather, it is necessary to monitor the biological parameters in order to define the differences in the ecosystem. 相似文献
102.
广州精通教育基地校园二期环境设计,延续与强化校区总体规划设计精神,充分结合校区的地形地貌,以人为本,因地制宜,抓住校园文化内涵,将校园精神贯穿于环境设计的各个部分,形成极近自然的校园景观环境。 相似文献
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以盐碱化湖泊和池塘水进行凡纳滨对虾(Litopenaeus vannamei Boone,1931)幼虾生长试验,探讨碱水环境对虾体重生长速度与Ca2 、Mg2 、Ca2 Mg2 质量浓度及(1/2Ca2 )/(1/2 Mg2 )的关系,为碱水水域养殖提供科学依据.结果表明,在碱度为10.32~38.50 mmol/L、盐度1.02~3.34g/L、pH 8.5~9.5的水环境中,体长为10~20 mm的幼虾饲养27 d的体重生长速度为(0.95 0.18)mg/d,存活率(47.5±14.5)%.不同水环境存活率差异显著(P<0.01),体重生长速度差别不明显(P>0.05).体重生长速度与环境因子问的相关性不明显.通过驯化提高幼虾对水环境的综合适应能力,是碱水水域养殖对虾的重要途径. 相似文献
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Processes of collating a European fisheries database to meet the objectives of the European Union Water Framework Directive 总被引:1,自引:0,他引:1
U. BEIER & E. DEGERMAN A. MELCHER C. ROGERS H. WIRLÖF 《Fisheries Management and Ecology》2007,14(6):407-416
Abstract FIsh Database of European Streams, a common database for the FAME project, was merged using existing data on electric fishing and environmental data. FIsh Database of European Stream is a relational database with eight tables. Metrics based on classification of fish species into guilds were calculated, and provided in separate tables. FIsh Database of European Stream contained information about 150 freshwater fish species, from 12 countries, 17 ecoregions, 40 main river regions, 2651 rivers and 8228 sites. Examples of data coverage and use are given. Relationships between environmental variables were illustrated using principal component analysis, which resulted in three environmental components – latitude, size and altitude. Environmental component scores were correlated with fish metrics used in the European Fish Index. Results exemplify how fish guilds reflect gradients in environmental variation. Benefits and problems concerning standardisation and data availability at the global level are discussed. 相似文献
107.
Abstract – Temperature fluctuation has been shown to affect somatic growth rates and metabolic functions of fish, but little is known about the effects of fluctuating temperatures on life-history traits. We examined these effects on female Japanese medaka ( Oryzias latipes ) reared from hatch to maturity at two mean temperatures (27 and 30 °C) with diel temperatures either held constant or allowed to fluctuate ±5 °C. Feeding regimes were manipulated to equilibrate medaka growth rates in all treatments. Age and length at maturity decreased as a result of thermal fluctuation, whereas there was no effect of temperature fluctuation on the proportion of fish attaining maturity or on the number of eggs produced by a mature female. We hypothesise that short-term high temperatures associated with temperature fluctuation decreases development time, whereas reduced energy conversion efficiency at higher temperatures does not allow for increased egg production. 相似文献
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蒋仕伟 《四川畜牧兽医学院学报》2008,(3):6-8
当今世界,欧洲环境治理绩效突出。究其原因,环境政策发挥了指导性作用。而这对于环境形势目最严峻的中国具有十分重要的借鉴意义。文中对欧洲环境政策发展历程、原则及挑战进行了细致分析,以供相关研究机构和学者参考。 相似文献