To provide basic information for studying balancing mechanism of nutrition environment in aquaculture ponds, sediment samples were collected periodically during the breeding process of tilapia in ponds. Then various t...To provide basic information for studying balancing mechanism of nutrition environment in aquaculture ponds, sediment samples were collected periodically during the breeding process of tilapia in ponds. Then various types of nutrient content of the samples were detected and the changing rule was summarized. The results showed that dry weight of the sediment and content of TP, TN and TOC generally presented a trend of first increasing and then decreasing. The main production period of each nutrient was from July to September and the production percentage was close to 80% of the total production. The content of NH4^＋-N increased gradually and reached a peak in early August, then maintained at the peak level. NO2^--N content of the sediment in each pond was basically the same in the earlier aquaculture stage and decreased in middle stage with a big difference, then rose again in the later stage.展开更多
An artifi cial oyster shell reef was deployed in Rongcheng Bay, East China. However, the effects of this reef on the surrounding macrobenthic communities were unknown. We compared sedimentary factors, macrobenthic bio...An artifi cial oyster shell reef was deployed in Rongcheng Bay, East China. However, the effects of this reef on the surrounding macrobenthic communities were unknown. We compared sedimentary factors, macrobenthic biomass, abundance, and community composition and ecological indicators between the reef and non-reef areas over a one year period. The mean values for chlorophyll a(Chl a), total organic matter(TOM), total organic carbon(TOC), and total nitrogen(TN) content in surface sediments in the reef area were slightly higher than those in the non-reef area. The Chl a levels differed signifi cantly between the two areas, but the TOM, TOC, and TN were not signifi cantly different. The abundance of crustaceans was signifi cantly different between the two areas, but the abundance and biomass of polychaetes, echinoderms, mollusk did not differ signifi cantly. The permutational multivariate analysis of variance(PERMANOVA) revealed that the macrobenthic community differed signifi cantly through time and analysis of similarity multivariate analyses(ANOSIM) revealed that the macrobenthic community differed signifi cantly in some months. The ecological indicators revealed that the environmental quality of the reef area was slightly better than that of the non-reef area. Overall, our results suggest that the artifi cial oyster shell reef may change the macrobenthic community and the quality of the environment. Despite the lack of an effect in the short term, long-term monitoring is still needed to evaluate the effects of artifi cial oyster shell reefs on macrobenthic communities.展开更多
We studied diatom distribution from 62 samples from the uppermost 1 cm of sedimem in the South China Sea （SCS）, using grabs or box corers in three cruises between 2001-2007. Fifty six genera, 256 species and their v...We studied diatom distribution from 62 samples from the uppermost 1 cm of sedimem in the South China Sea （SCS）, using grabs or box corers in three cruises between 2001-2007. Fifty six genera, 256 species and their varieties were identified. Dominating species included Coscinodiscus africanus, Coscinodiscus nodulifer, Cyclotella stylorum, Hemidiscus cuneiformis, Melosira sulcata, Nitzschia marina, Roperia tesselata, Thalassionema nitzschioides, Thalassiosira excentrica, and Thalassiothrix longissima. Most surface sediments in the SCS were rich ill diatoms, except for a few coarse samples. Average diatom abundance in the study area was 104 607 valve/g. In terms of the abundance, ecology, and spatial distribution, seven diatom zones （Zones 1-7） were recognized. Zone 1 （northern continental shelf） is affected by warm currents, SCS northern branch of the Kuroshio, and northern coastal currents; Zone 2 （northwestern continental shelf） is affected by intense coastal currents; Zone 3 （Xisha Islands sea area） is a bathyal environment with transitional water masses; Zone 4 （sea basin） is a bathyal-to-deep sea with stable and uniform central water masses in a semi-enclosed marginal sea; Zone 5 （Nansba Islands marine area） is a pelagic environment with relatively high surface temperature; Zone 6 （northern Sunda Shelf） is a tropical shelf environment; and Zone 7 （northern Kalimantan Island shelf area） is affected by warm waters from the Indian Ocean and coastal waters. The data indicate that these diatom zones are closely related to topography, hydrodynamics, temperature, nutrients and especially the salinity. Better understanding of the relationship between diatom distribution and the oceanographic factors would help in the reconstruction of the SCS in the past.展开更多
Understanding organic matter characteristics （e.g., amount and state） of sediments is necessary for evaluating both the sediment and water environments; however, methods that have been proposed to investigate these ...Understanding organic matter characteristics （e.g., amount and state） of sediments is necessary for evaluating both the sediment and water environments; however, methods that have been proposed to investigate these characteristics are relatively expensive. This study attempted to evaluate the organic matter characteristics of littoral sediments by employing solely the loss on ignition （LOI） method, which is the most economical and accessible method in developing countries. Different types of sediments were first oven dried at 100 ~C and then continuously burned at 200, 300, 400, 500, and 600 ~C for 4 h at each temperature. The mass LOI at each temperature was calculated and compared with the 100 ℃oven-dried weight. Our results suggested that the mass LOI across the temperature range of 200-300 ℃（LOI200-300）：mass LOI at 600 ℃ （LOI600） ratio （LOI200-300/LOI600） could represent different types of sediments as well as the organic matter：organic C ratio. Compared with the sediments unaffected by wastewater, the sediments that were more influenced by the inflow of domestic wastewater had a higher LOI200-300/LOI600. Interestingly, LOI200-300/LOI600 could also represent changes in the organic matter characteristics as a function of organic matter decomposition in sediments. In conclusion, the organic matter characteristics of littoral sediments could be evaluated using solely the LOI method, particularly with LOI200 - 300/LOI600.展开更多
基金Supported by Fundamental Research Funds in Central Public Welfare Research Institutes(2015JBFM28)National Agriculture Industrial Technology(CARS-49)~~
文摘To provide basic information for studying balancing mechanism of nutrition environment in aquaculture ponds, sediment samples were collected periodically during the breeding process of tilapia in ponds. Then various types of nutrient content of the samples were detected and the changing rule was summarized. The results showed that dry weight of the sediment and content of TP, TN and TOC generally presented a trend of first increasing and then decreasing. The main production period of each nutrient was from July to September and the production percentage was close to 80% of the total production. The content of NH4^＋-N increased gradually and reached a peak in early August, then maintained at the peak level. NO2^--N content of the sediment in each pond was basically the same in the earlier aquaculture stage and decreased in middle stage with a big difference, then rose again in the later stage.
基金Supported by the National Marine Public Welfare Research Project(Nos.200805069,201305043)the National Natural Science Foundation of China(No.41106134)National Key Technology Research and Development Program(Nos.2011BAD13B02,2010BAC68B01)
文摘An artifi cial oyster shell reef was deployed in Rongcheng Bay, East China. However, the effects of this reef on the surrounding macrobenthic communities were unknown. We compared sedimentary factors, macrobenthic biomass, abundance, and community composition and ecological indicators between the reef and non-reef areas over a one year period. The mean values for chlorophyll a(Chl a), total organic matter(TOM), total organic carbon(TOC), and total nitrogen(TN) content in surface sediments in the reef area were slightly higher than those in the non-reef area. The Chl a levels differed signifi cantly between the two areas, but the TOM, TOC, and TN were not signifi cantly different. The abundance of crustaceans was signifi cantly different between the two areas, but the abundance and biomass of polychaetes, echinoderms, mollusk did not differ signifi cantly. The permutational multivariate analysis of variance(PERMANOVA) revealed that the macrobenthic community differed signifi cantly through time and analysis of similarity multivariate analyses(ANOSIM) revealed that the macrobenthic community differed signifi cantly in some months. The ecological indicators revealed that the environmental quality of the reef area was slightly better than that of the non-reef area. Overall, our results suggest that the artifi cial oyster shell reef may change the macrobenthic community and the quality of the environment. Despite the lack of an effect in the short term, long-term monitoring is still needed to evaluate the effects of artifi cial oyster shell reefs on macrobenthic communities.
基金Supported by the National Natural Science Foundation of China(Nos.40676026,41076079,40831160519)the Basic Research Program of China(973Program)(No.2010CB428704)
文摘We studied diatom distribution from 62 samples from the uppermost 1 cm of sedimem in the South China Sea （SCS）, using grabs or box corers in three cruises between 2001-2007. Fifty six genera, 256 species and their varieties were identified. Dominating species included Coscinodiscus africanus, Coscinodiscus nodulifer, Cyclotella stylorum, Hemidiscus cuneiformis, Melosira sulcata, Nitzschia marina, Roperia tesselata, Thalassionema nitzschioides, Thalassiosira excentrica, and Thalassiothrix longissima. Most surface sediments in the SCS were rich ill diatoms, except for a few coarse samples. Average diatom abundance in the study area was 104 607 valve/g. In terms of the abundance, ecology, and spatial distribution, seven diatom zones （Zones 1-7） were recognized. Zone 1 （northern continental shelf） is affected by warm currents, SCS northern branch of the Kuroshio, and northern coastal currents; Zone 2 （northwestern continental shelf） is affected by intense coastal currents; Zone 3 （Xisha Islands sea area） is a bathyal environment with transitional water masses; Zone 4 （sea basin） is a bathyal-to-deep sea with stable and uniform central water masses in a semi-enclosed marginal sea; Zone 5 （Nansba Islands marine area） is a pelagic environment with relatively high surface temperature; Zone 6 （northern Sunda Shelf） is a tropical shelf environment; and Zone 7 （northern Kalimantan Island shelf area） is affected by warm waters from the Indian Ocean and coastal waters. The data indicate that these diatom zones are closely related to topography, hydrodynamics, temperature, nutrients and especially the salinity. Better understanding of the relationship between diatom distribution and the oceanographic factors would help in the reconstruction of the SCS in the past.
基金the Grantin-Aid for Science Research from the Japan Society for the Promotion of Science (Nos.26820204 and 26630229)
文摘Understanding organic matter characteristics （e.g., amount and state） of sediments is necessary for evaluating both the sediment and water environments; however, methods that have been proposed to investigate these characteristics are relatively expensive. This study attempted to evaluate the organic matter characteristics of littoral sediments by employing solely the loss on ignition （LOI） method, which is the most economical and accessible method in developing countries. Different types of sediments were first oven dried at 100 ~C and then continuously burned at 200, 300, 400, 500, and 600 ~C for 4 h at each temperature. The mass LOI at each temperature was calculated and compared with the 100 ℃oven-dried weight. Our results suggested that the mass LOI across the temperature range of 200-300 ℃（LOI200-300）：mass LOI at 600 ℃ （LOI600） ratio （LOI200-300/LOI600） could represent different types of sediments as well as the organic matter：organic C ratio. Compared with the sediments unaffected by wastewater, the sediments that were more influenced by the inflow of domestic wastewater had a higher LOI200-300/LOI600. Interestingly, LOI200-300/LOI600 could also represent changes in the organic matter characteristics as a function of organic matter decomposition in sediments. In conclusion, the organic matter characteristics of littoral sediments could be evaluated using solely the LOI method, particularly with LOI200 - 300/LOI600.
