Substrate is a critical environmental factor affecting the activity of bivalves. To examine the effect of the substrate component on the growth and survival of juvenile sunray surf clam(Mactra chinensis Philippi), a s...Substrate is a critical environmental factor affecting the activity of bivalves. To examine the effect of the substrate component on the growth and survival of juvenile sunray surf clam(Mactra chinensis Philippi), a series of short-term experiments were conducted using a variety of substrates with different ratios of sand to mud. The experimental group cultured without substrate showed poor survival, with all juveniles died after day 20. The juveniles cultured in mud without sand showed a lower survival rate(25.54% ± 0.40% on day 45) than those in other groups. The juveniles cultured in sand without mud, or the mixtures of sand and mud with a ratio of 1:1 and 2:1, respectively, exhibited modest survival at day 45. Maximal weight gain rate(WGR), shell length growth rate(LGR), and specific growth rate(SGR) were observed when the sand concentration was 61.97%, 77.69%, and 64.64%, respectively. As the fast growth and high survival were observed when the sand to mud ratio was 1:1(50% sand) and 2:1(67% sand), a sand concentration of more than 50% is optimal. The optimal concentration of sand in the substrate for rearing juvenile sunray surf clams was 67% which resulted in the fastest growth and highest survival. These results can be used to developing a nursery/farming technique of improving the yield of sunray surf clams.展开更多
The effects of nitrogen(N) addition on microbial biomass, bacterial abundance, and community composition in sediment colonized by Suaeda heteroptera were examined by chloroform fumigation extraction method, real-time ...The effects of nitrogen(N) addition on microbial biomass, bacterial abundance, and community composition in sediment colonized by Suaeda heteroptera were examined by chloroform fumigation extraction method, real-time quantitative polymerase chain reaction, and denaturing gradient gel electrophoresis(DGGE) in a salt marsh located in Shuangtai Estuary, China. The sediment samples were collected from plots treated with different amounts of a single N fertilizer(urea supplied at 0.1, 0.2, 0.4 and 0.8 g/kg(nitrogen content in sediment) and different forms of N fertilizers(urea,(NH_4)_2SO_4, and NH_4NO_3, each supplied at 0.2 g/kg(calculated by nitrogen).The fertilizers were applied 1–4 times during the plant-growing season in May, July, August, and September of 2013. Untreated plots were included as a control. The results showed that both the amount and form of N positively influenced microbial biomass carbon, microbial biomass nitrogen, and bacterial abundance. The DGGE profiles revealed that the bacterial community composition was also affected by the amount and form of N.Thus, our findings indicate that short-term N amendment increases microbial biomass and bacterial abundance,and alters the structure of bacterial community.展开更多
This study examines the impacts of short-term(6 months) fertilization on the community structure and abundance of ammonia-oxidizing betaproteobacteria(β-AOB) and the potential nitrification rate in sediment colonized...This study examines the impacts of short-term(6 months) fertilization on the community structure and abundance of ammonia-oxidizing betaproteobacteria(β-AOB) and the potential nitrification rate in sediment colonized by S uaeda heteroptera in a saltmarsh located in Shuangtai estuary, China. The sediment samples were collected from plots treated with different amounts of an N fertilizer(urea supplied at 0.1, 0.2, 0.4, and 0.8 g/kg(nitrogen content in dry sediment)), and with different forms of N fertilizers(urea,(NH4) 2 SO 4, and NH_4NO_3, each supplied at 0.2 g/kg). The fertilizers were applied 1–4 times during the plant-growing season in May, July, August and September of 2013. Untreated plots were included as a control. As revealed in denaturing gradient gel electrophoresis of the 16 S r RNA gene, the β-AOB community responded to both the amount and form of N. Real-time quantitative PCR indicated that both abundance and potential nitrification rate of β-AOB increased after N addition, regardless of concentration and form(except NH_4NO_3). These results provide evidence that short-term N application influences the sediment β-AOB community, β-AOB abundance and potential nitrification rate in a saltmarsh ecosystem.展开更多
基金supported by the earmarked fund for Modern Agro-industry Technology Research System (CARS48)grants from the ‘863’ Project of China (2012 AA10AA400)
文摘Substrate is a critical environmental factor affecting the activity of bivalves. To examine the effect of the substrate component on the growth and survival of juvenile sunray surf clam(Mactra chinensis Philippi), a series of short-term experiments were conducted using a variety of substrates with different ratios of sand to mud. The experimental group cultured without substrate showed poor survival, with all juveniles died after day 20. The juveniles cultured in mud without sand showed a lower survival rate(25.54% ± 0.40% on day 45) than those in other groups. The juveniles cultured in sand without mud, or the mixtures of sand and mud with a ratio of 1:1 and 2:1, respectively, exhibited modest survival at day 45. Maximal weight gain rate(WGR), shell length growth rate(LGR), and specific growth rate(SGR) were observed when the sand concentration was 61.97%, 77.69%, and 64.64%, respectively. As the fast growth and high survival were observed when the sand to mud ratio was 1:1(50% sand) and 2:1(67% sand), a sand concentration of more than 50% is optimal. The optimal concentration of sand in the substrate for rearing juvenile sunray surf clams was 67% which resulted in the fastest growth and highest survival. These results can be used to developing a nursery/farming technique of improving the yield of sunray surf clams.
基金The National Natural Science Foundation of China under contract No.41171389the Public Science and Technology Research Funds Projects of Ocean under contract No.201305043Program for Liaoning Excellent Talents in University under contract No.LR2013035
文摘The effects of nitrogen(N) addition on microbial biomass, bacterial abundance, and community composition in sediment colonized by Suaeda heteroptera were examined by chloroform fumigation extraction method, real-time quantitative polymerase chain reaction, and denaturing gradient gel electrophoresis(DGGE) in a salt marsh located in Shuangtai Estuary, China. The sediment samples were collected from plots treated with different amounts of a single N fertilizer(urea supplied at 0.1, 0.2, 0.4 and 0.8 g/kg(nitrogen content in sediment) and different forms of N fertilizers(urea,(NH_4)_2SO_4, and NH_4NO_3, each supplied at 0.2 g/kg(calculated by nitrogen).The fertilizers were applied 1–4 times during the plant-growing season in May, July, August, and September of 2013. Untreated plots were included as a control. The results showed that both the amount and form of N positively influenced microbial biomass carbon, microbial biomass nitrogen, and bacterial abundance. The DGGE profiles revealed that the bacterial community composition was also affected by the amount and form of N.Thus, our findings indicate that short-term N amendment increases microbial biomass and bacterial abundance,and alters the structure of bacterial community.
基金Supported by the National Natural Science Foundation of China(No.41171389)the Public Science and Technology Research Funds Projects of Ocean(No.201305043)the Program for Liaoning Excellent Talents in University(No.LR2013035)
文摘This study examines the impacts of short-term(6 months) fertilization on the community structure and abundance of ammonia-oxidizing betaproteobacteria(β-AOB) and the potential nitrification rate in sediment colonized by S uaeda heteroptera in a saltmarsh located in Shuangtai estuary, China. The sediment samples were collected from plots treated with different amounts of an N fertilizer(urea supplied at 0.1, 0.2, 0.4, and 0.8 g/kg(nitrogen content in dry sediment)), and with different forms of N fertilizers(urea,(NH4) 2 SO 4, and NH_4NO_3, each supplied at 0.2 g/kg). The fertilizers were applied 1–4 times during the plant-growing season in May, July, August and September of 2013. Untreated plots were included as a control. As revealed in denaturing gradient gel electrophoresis of the 16 S r RNA gene, the β-AOB community responded to both the amount and form of N. Real-time quantitative PCR indicated that both abundance and potential nitrification rate of β-AOB increased after N addition, regardless of concentration and form(except NH_4NO_3). These results provide evidence that short-term N application influences the sediment β-AOB community, β-AOB abundance and potential nitrification rate in a saltmarsh ecosystem.
