At a temperature of 23.0 - 24.8℃, the mixed feeding of Japanese anchovy larvae was initiated 24 h before the yolk-sac was exhausted. The point of no return （PNR） was reached on the 6th day after hatching. On the 4t...At a temperature of 23.0 - 24.8℃, the mixed feeding of Japanese anchovy larvae was initiated 24 h before the yolk-sac was exhausted. The point of no return （PNR） was reached on the 6th day after hatching. On the 4th day after hatching, the pectoral angle appeared in both fed and unfed anchovy larvae although it was more evident and sharper in the starved and the PNR stage larvae than in the fed ones. According to observations of larvae collected in the sea, the pectoral angles were evident not only in the larvae of 3.62 - 7.44 mm in standard length, but also in the larvae of 2.70 mm in standard length with remnants of yolk. The pectoral angles became diffuse when the larvae reached 7.84 mm and vanished at 9.86 mm. The pectoral angle cannot be used as a criterion to distinguish healthy from starving larvae.展开更多
Temporal changes in biological characteristics of small yellow croaker Larimichthys polyactis in the Yellow Sea were examined for the period of 1960–2008. The body size and age of small yellow croaker decreased subst...Temporal changes in biological characteristics of small yellow croaker Larimichthys polyactis in the Yellow Sea were examined for the period of 1960–2008. The body size and age of small yellow croaker decreased substantially, in particular, average length of fish in 2008 was reduced by ~85% than those occurring in 1985, and at that time ~93% of the total catch was dominated by one-year-old individuals. Correspondingly, growth parameters also varied significantly over the years, i.e., k（growth coefficient） and t_0（zero-length age） gradually increased from 0.26 and –0.58 year in 1960 to 0.56 and –0.25 year in 2008, respectively. Although, L∞（body length）sharply decreased from 34.21 cm in 1960 to 24.06 cm in 2008, and t_r（inflexion age） decreased from 3.78 year in1960 to 1.61 year in 2008. There was a great increase both in natural mortality coefficient and fishing mortality coefficient. However, according to the gray correlation analysis, changes in the biological characteristics of small yellow croaker were induced by different stressors ranked as： fishing vessel power〉feeding grade〉sea surface temperature. This study suggests that the active fishery management measures for biological characters of fish populations should be considered.展开更多
隧道凿岩台车钻孔震源实测信号具有数据杂乱、噪声干扰严重及偶发性采集异常等特点,难以直接用于模拟数据训练后的神经网络模型.针对这一问题,首先基于U-Net去噪神经网络,将互相关、Automatic Gain Control(AGC)和归一化处理作为U-Net...隧道凿岩台车钻孔震源实测信号具有数据杂乱、噪声干扰严重及偶发性采集异常等特点,难以直接用于模拟数据训练后的神经网络模型.针对这一问题,首先基于U-Net去噪神经网络,将互相关、Automatic Gain Control(AGC)和归一化处理作为U-Net神经网络的预处理层,开展信号降噪处理,有效提升了凿岩台车含噪钻孔震源与无噪地震记录间复杂映射关系的拟合效果.然后,构建了基于Generative Adversarial Nets(GAN)的对抗式迁移学习神经网络,将隧道的真实地震数据进行迁移,实现了真实数据在已训练完成的U-Net去噪神经网络中的有效应用.最后,依托实际工程对该方法进行评价.结果表明,采用提出的去噪方法,可有效去除地震记录中的噪声干扰,探测结果与实际开挖情况基本吻合,初步验证了该方法的可行性与有效性.展开更多
Laizhou Bay provides a critical spawning and nursery habitat for many fishery species,including commercially important species,such as Fenneropenaeus chinensis and Larimichthys polyactis.The bay is severely stressed d...Laizhou Bay provides a critical spawning and nursery habitat for many fishery species,including commercially important species,such as Fenneropenaeus chinensis and Larimichthys polyactis.The bay is severely stressed due to high fishing pressure and environmental changes.Based on the long-term ecosystem surveys in Laizhou Bay during the main spawning period(May) of most fishery species from 1959 to 2008,the responses of the Laizhou Bay fishery ecosystem were analyzed here,including regime shifts in species composition,biomass,species diversity,zooplankton,phytoplankton,and environmental variables.The dominant species of large-size and high economic value(e.g.Trichiurus haumela,L.polyactis) have been replaced by the short-lived,low-trophic-level planktivorous pelagic species(e.g.Setipinna taty,Engraulis japonicus) since the 1980s,and it is probable that the small-sized pelagic fishes have been recently replaced by invertebrates(e.g.Oratosquilla oratoria,Crangon affinis).The biomass of fishery resources declined continuously from 423.6 kg haul?1 h?1 in 1959 to 164.6 kg haul?1 h?1 in 1982,37.7 kg haul?1 h?1 in 1993,and less than 8 kg haul?1 h?1 in 1998-2008.Moreover,the biomass of zooplankton showed an increasing trend during 1959-2006,but showed a slight decline in 2008.The abundance of phytoplankton increased from 1959 through 1982,decreased substantially in 1993,and increased again until 2004.More recently,however,the phytoplankton abundance was very low.The sea surface temperature(SST) and sea bottom temperature(SBT) in May increased by 0.23°C a?1 and 0.16°C a?1,respectively,during 1982-2008.The salinity in May showed large fluctuations and reached its lowest values in 2004 and 2006.The ratio of dissolved inorganic nitrogen(DIN) to dissolved inorganic phosphate(DIP) increased.However,the dissolved silicon(DSi):DIP and DSi:DIN ratios decreased to a low level during 1959-2008.These changes seriously impacted primary production,and cascade effects then changed the structure and function of the fishery ecosystem.Further analysis indicated that multiple stresses caused the alterations in the structure of the Laizhou Bay fishery ecosystem.The top-down effect was identified as the main influence on the fishery species(at the top of the food chain) over the past five decades due to the increasing fishing pressure,whereas the bottom-up effect increased over the past three decades due to the strong variations in the environment.展开更多
文摘At a temperature of 23.0 - 24.8℃, the mixed feeding of Japanese anchovy larvae was initiated 24 h before the yolk-sac was exhausted. The point of no return （PNR） was reached on the 6th day after hatching. On the 4th day after hatching, the pectoral angle appeared in both fed and unfed anchovy larvae although it was more evident and sharper in the starved and the PNR stage larvae than in the fed ones. According to observations of larvae collected in the sea, the pectoral angles were evident not only in the larvae of 3.62 - 7.44 mm in standard length, but also in the larvae of 2.70 mm in standard length with remnants of yolk. The pectoral angles became diffuse when the larvae reached 7.84 mm and vanished at 9.86 mm. The pectoral angle cannot be used as a criterion to distinguish healthy from starving larvae.
基金The National Basic Research Program(973 Program)of China under contract No.2015CB453303the Aoshan Scientific and Technical Innovation Program under contract No.2015ASKJ02-05the Taishan Scholar Project Special Fund
文摘Temporal changes in biological characteristics of small yellow croaker Larimichthys polyactis in the Yellow Sea were examined for the period of 1960–2008. The body size and age of small yellow croaker decreased substantially, in particular, average length of fish in 2008 was reduced by ~85% than those occurring in 1985, and at that time ~93% of the total catch was dominated by one-year-old individuals. Correspondingly, growth parameters also varied significantly over the years, i.e., k（growth coefficient） and t_0（zero-length age） gradually increased from 0.26 and –0.58 year in 1960 to 0.56 and –0.25 year in 2008, respectively. Although, L∞（body length）sharply decreased from 34.21 cm in 1960 to 24.06 cm in 2008, and t_r（inflexion age） decreased from 3.78 year in1960 to 1.61 year in 2008. There was a great increase both in natural mortality coefficient and fishing mortality coefficient. However, according to the gray correlation analysis, changes in the biological characteristics of small yellow croaker were induced by different stressors ranked as： fishing vessel power〉feeding grade〉sea surface temperature. This study suggests that the active fishery management measures for biological characters of fish populations should be considered.
文摘隧道凿岩台车钻孔震源实测信号具有数据杂乱、噪声干扰严重及偶发性采集异常等特点,难以直接用于模拟数据训练后的神经网络模型.针对这一问题,首先基于U-Net去噪神经网络,将互相关、Automatic Gain Control(AGC)和归一化处理作为U-Net神经网络的预处理层,开展信号降噪处理,有效提升了凿岩台车含噪钻孔震源与无噪地震记录间复杂映射关系的拟合效果.然后,构建了基于Generative Adversarial Nets(GAN)的对抗式迁移学习神经网络,将隧道的真实地震数据进行迁移,实现了真实数据在已训练完成的U-Net去噪神经网络中的有效应用.最后,依托实际工程对该方法进行评价.结果表明,采用提出的去噪方法,可有效去除地震记录中的噪声干扰,探测结果与实际开挖情况基本吻合,初步验证了该方法的可行性与有效性.
基金supported by Special Fund for Agro-scientific Research in the Public Interest(Grant No.200903005)National Basic Research Program of China(Grant Nos.2011CB409805 and 2010CB951204)Taishan Scholar Program of Shandong Province
文摘Laizhou Bay provides a critical spawning and nursery habitat for many fishery species,including commercially important species,such as Fenneropenaeus chinensis and Larimichthys polyactis.The bay is severely stressed due to high fishing pressure and environmental changes.Based on the long-term ecosystem surveys in Laizhou Bay during the main spawning period(May) of most fishery species from 1959 to 2008,the responses of the Laizhou Bay fishery ecosystem were analyzed here,including regime shifts in species composition,biomass,species diversity,zooplankton,phytoplankton,and environmental variables.The dominant species of large-size and high economic value(e.g.Trichiurus haumela,L.polyactis) have been replaced by the short-lived,low-trophic-level planktivorous pelagic species(e.g.Setipinna taty,Engraulis japonicus) since the 1980s,and it is probable that the small-sized pelagic fishes have been recently replaced by invertebrates(e.g.Oratosquilla oratoria,Crangon affinis).The biomass of fishery resources declined continuously from 423.6 kg haul?1 h?1 in 1959 to 164.6 kg haul?1 h?1 in 1982,37.7 kg haul?1 h?1 in 1993,and less than 8 kg haul?1 h?1 in 1998-2008.Moreover,the biomass of zooplankton showed an increasing trend during 1959-2006,but showed a slight decline in 2008.The abundance of phytoplankton increased from 1959 through 1982,decreased substantially in 1993,and increased again until 2004.More recently,however,the phytoplankton abundance was very low.The sea surface temperature(SST) and sea bottom temperature(SBT) in May increased by 0.23°C a?1 and 0.16°C a?1,respectively,during 1982-2008.The salinity in May showed large fluctuations and reached its lowest values in 2004 and 2006.The ratio of dissolved inorganic nitrogen(DIN) to dissolved inorganic phosphate(DIP) increased.However,the dissolved silicon(DSi):DIP and DSi:DIN ratios decreased to a low level during 1959-2008.These changes seriously impacted primary production,and cascade effects then changed the structure and function of the fishery ecosystem.Further analysis indicated that multiple stresses caused the alterations in the structure of the Laizhou Bay fishery ecosystem.The top-down effect was identified as the main influence on the fishery species(at the top of the food chain) over the past five decades due to the increasing fishing pressure,whereas the bottom-up effect increased over the past three decades due to the strong variations in the environment.
