The paper deals with the studies on the cell abundance, the composition of dominant species, size fractionated biomass and productivity of phytoplankton, new production, the environmentally restricted mechanism in the...The paper deals with the studies on the cell abundance, the composition of dominant species, size fractionated biomass and productivity of phytoplankton, new production, the environmentally restricted mechanism in the Prydz Bay and the adjacent Indian sector of the Southern Ocean during the austral summer 1998/1999. The results showed that there was marked feature of spatial zonation in the sea areas investigated. In the Prydz Bay and its adjacent continental shelf, the biomass and productivity of phytoplankton were high; those of continental slope and open ocean area were obviously low. The nutrient concentration had opposite distribution trend, due to the consumption of phytoplankton. It mainly affected by the vertical stability of water column, grazing pressure of zooplankton, temperature and light etc. The results of size-fractionation showed that the average contribution of netplankton to total chlorophyll a in studied sea areas was 52.2 %, those of nano- and picoplankton were 29.4 % and 18.4 %, respectively. The average contribution of netplankton to total primary production was 52.4 %, those of nano- and picoplankton were 28.7 % and 18.9 %, separately. It is same as previous conclusion that the contribution of picoplankton to productivity is slightly larger than that to biomass of phytoplankton communities. The average new production and f-ratio were 230.6 mg/ (m(2.)d) and 0.43, respectively.展开更多
Satellite-derived phytoplankton pigment absorption （aph） has been used as a key predictor of phytoplankton photosynthetic efficiency to estimate global ocean net primary production （NPP）. In this study, an aph-bas...Satellite-derived phytoplankton pigment absorption （aph） has been used as a key predictor of phytoplankton photosynthetic efficiency to estimate global ocean net primary production （NPP）. In this study, an aph-based NPP model （AbPM） with four input parameters including the photosynthetically available radiation （PAR）, diffuse attenuation at 490 nm （Ka（490））, euphotic zone depth （Zeu） and the phytoplankton pigment absorption coefficient （aph） is compared with the chlorophyll-based model and carbon-based model. It is found that the AbPM has significant advantages on the ocean NPP estimation compared with the chlorophyll-based model and carbon- based model. For example, AbPM greatly outperformed the other two models at most monitoring sites and had the best accuracy, including the smallest values of RMSD and bias for the NPP estimate, and the best correlation between the observations and the modeled NPPs. In order to ensure the robustness of the model, the uncertainty in NPP estimates of the AbPM was assessed using a Monte Carlo simulation. At first, the frequency histograms of simple difference （fi）, and logarithmic difference （~LOG） between model estimates and in situ data confirm that the two input parameters （Zeu and PAR） approximate the Normal Distribution, and another two input parameters （aph and Ka（490）） approximate the logarithmic Normal Distribution. Second, the uncertainty in NPP estimates in the AbPM was assessed by using the Monte Carlo simulation. Here both the PB （percentage bias）, defined as the ratio of ANPP to the retrieved NPP, and the CV （coefficient of variation）, defined as the ratio of the standard deviation to the mean are used to indicate the uncertainty in the NPP brought by input parameter to AbPM model. The uncertainty related to magnitude is denoted by PB and the uncertainty related to scatter range is denoted by CV. Our investigations demonstrate that PB of NPP uncertainty brought by all parameters with an annual mean of 5.5% covered a range of -5%-15% for the global ocean. The PB uncertainty of AbPM model was mainly caused by aph; the PB of NPP uncertainty brought by aph had an annual mean of 4.1% for the global ocean. The CV brought by all the parameters with an annual mean of 105% covered a range of 98%-134% for global ocean. For the coastal zone of Antarctica with higher productivity, the PB and CV of NPP uncertainty brought by all parameters had annual means of 7.1% and 121%, respectively, which are significantly larger than those obtained in the global ocean. This study suggests that the NPPs estimated by AbPM model are more accurate than others, but the magnitude and scatter range of NPP errors brought by input parameter to AbPM model could not be neglected, especially in the coastal area with high productivity. So the improving accuracy of satellite retrieval of input parameters should be necessary. The investigation also confirmed that the SST related correction is effective for improving the model accuracy in low temperature condition.展开更多
Seabirds are good candidates as ecological indicators, especially in under-studied ecosystems since they provide insights into marine ecosystem processes and functions at various trophic levels. Our review discusses s...Seabirds are good candidates as ecological indicators, especially in under-studied ecosystems since they provide insights into marine ecosystem processes and functions at various trophic levels. Our review discusses salient points on the present status of seabirds in the Bay of Bengal Large Marine Ecosystem;despite overall low seabird numbers and biomass, this region harbors 9 species of terns, one of the most threatened bird group worldwide, which are known to breed in various marine habitats of Andaman and Nicobar islands, in addition to the coastal areas of mainland. Further, we elaborate on employing seabirds as potential indicators of this ecosystem and how they outscore other taxa in this aspect. Finally, we argue that it is essentially to fill the gaps in our knowledge about the BOBLME, mainly about the interplay between seabirds, climate change and fisheries.展开更多
文摘The paper deals with the studies on the cell abundance, the composition of dominant species, size fractionated biomass and productivity of phytoplankton, new production, the environmentally restricted mechanism in the Prydz Bay and the adjacent Indian sector of the Southern Ocean during the austral summer 1998/1999. The results showed that there was marked feature of spatial zonation in the sea areas investigated. In the Prydz Bay and its adjacent continental shelf, the biomass and productivity of phytoplankton were high; those of continental slope and open ocean area were obviously low. The nutrient concentration had opposite distribution trend, due to the consumption of phytoplankton. It mainly affected by the vertical stability of water column, grazing pressure of zooplankton, temperature and light etc. The results of size-fractionation showed that the average contribution of netplankton to total chlorophyll a in studied sea areas was 52.2 %, those of nano- and picoplankton were 29.4 % and 18.4 %, respectively. The average contribution of netplankton to total primary production was 52.4 %, those of nano- and picoplankton were 28.7 % and 18.9 %, separately. It is same as previous conclusion that the contribution of picoplankton to productivity is slightly larger than that to biomass of phytoplankton communities. The average new production and f-ratio were 230.6 mg/ (m(2.)d) and 0.43, respectively.
基金The National Natural Science Fundation of China under contract No.41501389the Foundation of State Key Laboratory of Remote Sensing Science in China under contract No.OFSLRSS201509
文摘Satellite-derived phytoplankton pigment absorption （aph） has been used as a key predictor of phytoplankton photosynthetic efficiency to estimate global ocean net primary production （NPP）. In this study, an aph-based NPP model （AbPM） with four input parameters including the photosynthetically available radiation （PAR）, diffuse attenuation at 490 nm （Ka（490））, euphotic zone depth （Zeu） and the phytoplankton pigment absorption coefficient （aph） is compared with the chlorophyll-based model and carbon-based model. It is found that the AbPM has significant advantages on the ocean NPP estimation compared with the chlorophyll-based model and carbon- based model. For example, AbPM greatly outperformed the other two models at most monitoring sites and had the best accuracy, including the smallest values of RMSD and bias for the NPP estimate, and the best correlation between the observations and the modeled NPPs. In order to ensure the robustness of the model, the uncertainty in NPP estimates of the AbPM was assessed using a Monte Carlo simulation. At first, the frequency histograms of simple difference （fi）, and logarithmic difference （~LOG） between model estimates and in situ data confirm that the two input parameters （Zeu and PAR） approximate the Normal Distribution, and another two input parameters （aph and Ka（490）） approximate the logarithmic Normal Distribution. Second, the uncertainty in NPP estimates in the AbPM was assessed by using the Monte Carlo simulation. Here both the PB （percentage bias）, defined as the ratio of ANPP to the retrieved NPP, and the CV （coefficient of variation）, defined as the ratio of the standard deviation to the mean are used to indicate the uncertainty in the NPP brought by input parameter to AbPM model. The uncertainty related to magnitude is denoted by PB and the uncertainty related to scatter range is denoted by CV. Our investigations demonstrate that PB of NPP uncertainty brought by all parameters with an annual mean of 5.5% covered a range of -5%-15% for the global ocean. The PB uncertainty of AbPM model was mainly caused by aph; the PB of NPP uncertainty brought by aph had an annual mean of 4.1% for the global ocean. The CV brought by all the parameters with an annual mean of 105% covered a range of 98%-134% for global ocean. For the coastal zone of Antarctica with higher productivity, the PB and CV of NPP uncertainty brought by all parameters had annual means of 7.1% and 121%, respectively, which are significantly larger than those obtained in the global ocean. This study suggests that the NPPs estimated by AbPM model are more accurate than others, but the magnitude and scatter range of NPP errors brought by input parameter to AbPM model could not be neglected, especially in the coastal area with high productivity. So the improving accuracy of satellite retrieval of input parameters should be necessary. The investigation also confirmed that the SST related correction is effective for improving the model accuracy in low temperature condition.
文摘Seabirds are good candidates as ecological indicators, especially in under-studied ecosystems since they provide insights into marine ecosystem processes and functions at various trophic levels. Our review discusses salient points on the present status of seabirds in the Bay of Bengal Large Marine Ecosystem;despite overall low seabird numbers and biomass, this region harbors 9 species of terns, one of the most threatened bird group worldwide, which are known to breed in various marine habitats of Andaman and Nicobar islands, in addition to the coastal areas of mainland. Further, we elaborate on employing seabirds as potential indicators of this ecosystem and how they outscore other taxa in this aspect. Finally, we argue that it is essentially to fill the gaps in our knowledge about the BOBLME, mainly about the interplay between seabirds, climate change and fisheries.
