The production of dimethylsulfoniopropionate （DMSP） and its cleavage products （DMS） are well studied in phytoplankton worldwide. However, less is known about their sources, distributions, and impacts in the coast ...The production of dimethylsulfoniopropionate （DMSP） and its cleavage products （DMS） are well studied in phytoplankton worldwide. However, less is known about their sources, distributions, and impacts in the coast of China. We examined the production of DMSP and DMS in Phaeocvstis globosa Scherffel and other benthic macroalgae from the South China coast in relation to environmental conditions. P. globosa was a harmful marine microalgal species and its bloom took place in the eutrophic waters along the South China Sea frequently. It also produced high content of DMSP at different growth stages, with the highest concentration usually observed in the stationary period. Moreover, the production of DMSP in P. globosa was significantly affected by salinity and temperature with the highest contents associated with high salinity （e.g. 40） and low temperature （e.g. 20℃）. In field benthic macroalgae, there was also a marked difference in the DMSP of various species or different samples of the same species. Chlorophyll a contents were also determined for each macroalgal species. The highest chlorophyll a （238.7 ng/g fresh weight） was recorded in Chlorophyta Ulva lactuca at Guishan Island （Zhuhai）, while the lowest value （1.5 ng/g fresh weight） was found in Rhodophyta Gracilaria tenuistipitata in Zhanjiang. Further correlation analysis indicated that there was no significant relationship between the content of DMSP and chl-a in macroalgae samples （P〉 0.05）. All the results suggested that the production of DMSP in marine algae was not only species- and stage-related, but also greatly affected by various environmental factors.展开更多
The effects of varying nitrogen （N）： phosphorus （P） ratios on the growth and N-uptake and assimilation of the harmful dinoflagellates Prorocentrum minimum and Prorocentrum donghaiense were examined in turbidistat...The effects of varying nitrogen （N）： phosphorus （P） ratios on the growth and N-uptake and assimilation of the harmful dinoflagellates Prorocentrum minimum and Prorocentrum donghaiense were examined in turbidistat culture experiments. Algal cultures were supplied with media containing PO4^3- in various concentrations to obtain a wide range of N：P ratios. Experiments to determine rates of N uptake and assimilation of different N sources （NO^3-, NH4^＋, urea and glycine by P. minimum and NO3^-, NH4^＋ by P. donghaiense） were conducted using ^15-N tracer techniques at each N：P ratio. The growth rates suggested nutrient limitation at both high and low N：P ratios relative to the Redfield ratio. On a diel basis, the growth of both species was regulated by the light-dark cycle, which may be a result of regulation of both lightdependent growth and light-independent nutrient uptake. Maximum growth rates of both species always occurred at the beginning of light phase. In P-rich medium （low N：P ratio）, both species had higher N assimilation rates, suggesting N limitation. Low assimilation coefficients at high N：P ratios suggested P limitation of N uptake and assimilation. NO3 ^-and NH4^＋ contributed more than 90% of the total N uptake of P. minimum. Reduced N sources were more quickly assimilated than NO3^-. Highest average daily growth rates were recorded near an N：P ratio of 12 for both species. The N uptake rates of cultures at N：P ratios near Redfield ratio were more balanced with growth rates. The linkage between growth rates and N uptake/assimilation rates were conceptually described by the variation of cell N quota. The N：P ratios affect the N uptake and growth of Prorocentrum spp., and may regulate their bloom progression in eutrophic ecosystems.展开更多
We studied the phagotrophic ability of dinoflagellate strain Karenia mikimotoi KM-Lu （isolated from the South China Sea）, using fluorescent microspheres, bacteria isolated from the culture of K. mikimotoi and a mari...We studied the phagotrophic ability of dinoflagellate strain Karenia mikimotoi KM-Lu （isolated from the South China Sea）, using fluorescent microspheres, bacteria isolated from the culture of K. mikimotoi and a marine microalgae lsochrysis galbana. We found that K. mikimotoi cultured under conditions of high light intensity could ingest fluorescent microspheres （diameters 0.5 and 2.0 lain） and fluorescence-labeled bacteria and microalgae. Under a low light intensity, however, only fluorescent microspheres （diameter 0.5 μm） and fluorescence-labeled microalgae were ingested. K. mikimotoi showed better growth by ingesting living marine bacteria or microalgae I. galbana than the controls, either in nutrient-depleted or nutrient-replete conditions. In nutrient-depleted conditions, the growth ofK. mikirnotoi was more significant with L galbana as the prey item. In conclusion, the harmful dinoflagellate K. mikimotoi from the South China Sea has apparent phagotrophic ability, and some marine bacteria and microalgae may promote the growth of K. mikimotoi.展开更多
基金Supported by the National Natural Science Foundation of China (No. 41006092)Natural Science Foundation of Guangdong Province (No. 1015030101000002)
文摘The production of dimethylsulfoniopropionate （DMSP） and its cleavage products （DMS） are well studied in phytoplankton worldwide. However, less is known about their sources, distributions, and impacts in the coast of China. We examined the production of DMSP and DMS in Phaeocvstis globosa Scherffel and other benthic macroalgae from the South China coast in relation to environmental conditions. P. globosa was a harmful marine microalgal species and its bloom took place in the eutrophic waters along the South China Sea frequently. It also produced high content of DMSP at different growth stages, with the highest concentration usually observed in the stationary period. Moreover, the production of DMSP in P. globosa was significantly affected by salinity and temperature with the highest contents associated with high salinity （e.g. 40） and low temperature （e.g. 20℃）. In field benthic macroalgae, there was also a marked difference in the DMSP of various species or different samples of the same species. Chlorophyll a contents were also determined for each macroalgal species. The highest chlorophyll a （238.7 ng/g fresh weight） was recorded in Chlorophyta Ulva lactuca at Guishan Island （Zhuhai）, while the lowest value （1.5 ng/g fresh weight） was found in Rhodophyta Gracilaria tenuistipitata in Zhanjiang. Further correlation analysis indicated that there was no significant relationship between the content of DMSP and chl-a in macroalgae samples （P〉 0.05）. All the results suggested that the production of DMSP in marine algae was not only species- and stage-related, but also greatly affected by various environmental factors.
基金supported by the University of Maryland Center for Environmental Science (UMCES), Horn Point Laboratory. This is UMCES contribution number 4503
文摘The effects of varying nitrogen （N）： phosphorus （P） ratios on the growth and N-uptake and assimilation of the harmful dinoflagellates Prorocentrum minimum and Prorocentrum donghaiense were examined in turbidistat culture experiments. Algal cultures were supplied with media containing PO4^3- in various concentrations to obtain a wide range of N：P ratios. Experiments to determine rates of N uptake and assimilation of different N sources （NO^3-, NH4^＋, urea and glycine by P. minimum and NO3^-, NH4^＋ by P. donghaiense） were conducted using ^15-N tracer techniques at each N：P ratio. The growth rates suggested nutrient limitation at both high and low N：P ratios relative to the Redfield ratio. On a diel basis, the growth of both species was regulated by the light-dark cycle, which may be a result of regulation of both lightdependent growth and light-independent nutrient uptake. Maximum growth rates of both species always occurred at the beginning of light phase. In P-rich medium （low N：P ratio）, both species had higher N assimilation rates, suggesting N limitation. Low assimilation coefficients at high N：P ratios suggested P limitation of N uptake and assimilation. NO3 ^-and NH4^＋ contributed more than 90% of the total N uptake of P. minimum. Reduced N sources were more quickly assimilated than NO3^-. Highest average daily growth rates were recorded near an N：P ratio of 12 for both species. The N uptake rates of cultures at N：P ratios near Redfield ratio were more balanced with growth rates. The linkage between growth rates and N uptake/assimilation rates were conceptually described by the variation of cell N quota. The N：P ratios affect the N uptake and growth of Prorocentrum spp., and may regulate their bloom progression in eutrophic ecosystems.
基金Supported by the National Natural Science Foundation of China (Nos. 40606029, 40821004)the National Basic Research Program of China (973 Program) (No. 2010CB428705)a project of the Chinese Academy of Sciences (No. KZCX2-YW-Q07-04)
文摘We studied the phagotrophic ability of dinoflagellate strain Karenia mikimotoi KM-Lu （isolated from the South China Sea）, using fluorescent microspheres, bacteria isolated from the culture of K. mikimotoi and a marine microalgae lsochrysis galbana. We found that K. mikimotoi cultured under conditions of high light intensity could ingest fluorescent microspheres （diameters 0.5 and 2.0 lain） and fluorescence-labeled bacteria and microalgae. Under a low light intensity, however, only fluorescent microspheres （diameter 0.5 μm） and fluorescence-labeled microalgae were ingested. K. mikimotoi showed better growth by ingesting living marine bacteria or microalgae I. galbana than the controls, either in nutrient-depleted or nutrient-replete conditions. In nutrient-depleted conditions, the growth ofK. mikirnotoi was more significant with L galbana as the prey item. In conclusion, the harmful dinoflagellate K. mikimotoi from the South China Sea has apparent phagotrophic ability, and some marine bacteria and microalgae may promote the growth of K. mikimotoi.
文摘小三毛金藻(Prymnesium parvum Carter)是一种半咸水害藻，其代谢产物中含有几种毒素，可使鱼贝类中毒致死。1920年这种藻在荷兰沿海岛屿的咸水湖中首次发现，以后陆续在波罗地海区域(Bursa，1938)、丹麦(Ottersfrom等，1940)、以色列(Reich等，1947)、保加利亚(Valkanov，1964)、英格兰(Linolnshire River Board，1965)和苏联乌克兰(Шемчук等，1973)等地海湾、
