This study was designed to compare the effect of two exchange rates （ERs; 0.5 m^3 feed/kg and 1.5 m^3 feed/kg） in re-circulating aquaculture systems （RAS） on water quality and fish growth profiles on fish stocks ...This study was designed to compare the effect of two exchange rates （ERs; 0.5 m^3 feed/kg and 1.5 m^3 feed/kg） in re-circulating aquaculture systems （RAS） on water quality and fish growth profiles on fish stocks （200 indiv/m^3 of 251.4 g e 20.67 g） of gilthead bream, Sparus aurata. Water quality, fish growth, specific growth rate （SGR） and feed conversion ratio under the two ERs were examined for a period of six months. Inorganic nutrient in RAS, temperature, dissolved oxygen and pH were measured daily. Feeding regime effect was also determined on the fish quality and organoleptic characteristics and thus opts to energy optimization of the system. The fish reared under the 1.5 m^3 feed/kg ER demonstrate enhanced growth, the daily SGR and the conversion ratio. Sensory test analysis revealed differences in the organoleptic characteristics between the two experimental fish stocks with considerably high acceptance scores for fish reared at high ER. Nutrient concentrations： ammonia, nitrate, nitrite and phosphate were lower in RAS of the highest ER when compared to those reared under the 0.5 m3/kg feed. Results suggest an ER of 1.5 m^3 feed/kg improved both fish quality and growth profile of the gilthead bream.展开更多
Numerous efforts have been made to characterize forest carbon （C） cycles and stocks in various ecosystems. However, long-term observation on each component of the forest C cycle is still lacking. We measured C stock...Numerous efforts have been made to characterize forest carbon （C） cycles and stocks in various ecosystems. However, long-term observation on each component of the forest C cycle is still lacking. We measured C stocks and fluxes in three per- manent temperate forest plots （birch, oak and pine forest） during 2011-2014, and calculated the changes of the components of the C cycle related to the measurements during 1992-1994 at Mr. Dongling, Beijing, China. Forest net primary production in birch, oak, and pine plots was 5.32, 4.53, and 6.73 Mg C ha-1 a-1, respectively. Corresponding net ecosystem production was 0.12, 0.43, and 3.53 Mg C ha-1 a-1. The C stocks and fluxes in 2011-2014 were significantly larger than those in 1992-1994 in which the biomass C densities in birch, oak, and pine plots increased from 50.0, 37.7, and 54.0 Mg C ha-1 in 1994 to 101.5, 77.3, and 110.9 Mg C ha a in 2014; soil organic C densities increased from 207.0, 239.1, and 231.7 Mg C ha-1 to 214.8, 241.7, and 238.4 Mg C ha-l; and soil heterotrophic respiration increased from 2.78, 3.49, and 1.81 Mg C ha-1 a-1 to 5.20, 4.10, and 3.20 Mg C ha-1 a-l. These results suggest that the mountainous temperate forest ecosystems in Beijing have served as a carbon sink in the last two decades. These observations of C stocks and fluxes provided field-based data for a long-term study of C cycling in temperate forest ecosystems.展开更多
文摘This study was designed to compare the effect of two exchange rates （ERs; 0.5 m^3 feed/kg and 1.5 m^3 feed/kg） in re-circulating aquaculture systems （RAS） on water quality and fish growth profiles on fish stocks （200 indiv/m^3 of 251.4 g e 20.67 g） of gilthead bream, Sparus aurata. Water quality, fish growth, specific growth rate （SGR） and feed conversion ratio under the two ERs were examined for a period of six months. Inorganic nutrient in RAS, temperature, dissolved oxygen and pH were measured daily. Feeding regime effect was also determined on the fish quality and organoleptic characteristics and thus opts to energy optimization of the system. The fish reared under the 1.5 m^3 feed/kg ER demonstrate enhanced growth, the daily SGR and the conversion ratio. Sensory test analysis revealed differences in the organoleptic characteristics between the two experimental fish stocks with considerably high acceptance scores for fish reared at high ER. Nutrient concentrations： ammonia, nitrate, nitrite and phosphate were lower in RAS of the highest ER when compared to those reared under the 0.5 m3/kg feed. Results suggest an ER of 1.5 m^3 feed/kg improved both fish quality and growth profile of the gilthead bream.
基金supported by National Natural Science Foundation of China(31321061,31330012)National Basic Research Program of China on Global Change(2014CB954001)
文摘Numerous efforts have been made to characterize forest carbon （C） cycles and stocks in various ecosystems. However, long-term observation on each component of the forest C cycle is still lacking. We measured C stocks and fluxes in three per- manent temperate forest plots （birch, oak and pine forest） during 2011-2014, and calculated the changes of the components of the C cycle related to the measurements during 1992-1994 at Mr. Dongling, Beijing, China. Forest net primary production in birch, oak, and pine plots was 5.32, 4.53, and 6.73 Mg C ha-1 a-1, respectively. Corresponding net ecosystem production was 0.12, 0.43, and 3.53 Mg C ha-1 a-1. The C stocks and fluxes in 2011-2014 were significantly larger than those in 1992-1994 in which the biomass C densities in birch, oak, and pine plots increased from 50.0, 37.7, and 54.0 Mg C ha-1 in 1994 to 101.5, 77.3, and 110.9 Mg C ha a in 2014; soil organic C densities increased from 207.0, 239.1, and 231.7 Mg C ha-1 to 214.8, 241.7, and 238.4 Mg C ha-l; and soil heterotrophic respiration increased from 2.78, 3.49, and 1.81 Mg C ha-1 a-1 to 5.20, 4.10, and 3.20 Mg C ha-1 a-l. These results suggest that the mountainous temperate forest ecosystems in Beijing have served as a carbon sink in the last two decades. These observations of C stocks and fluxes provided field-based data for a long-term study of C cycling in temperate forest ecosystems.
