Dilution experiments were performed to examine the growth rate and grazing mortality rate of size-fractionated phytoplankton at three typical stations, inside and outside the bay, in the spring and summer of 2003 in t...Dilution experiments were performed to examine the growth rate and grazing mortality rate of size-fractionated phytoplankton at three typical stations, inside and outside the bay, in the spring and summer of 2003 in the Jiaozhou Bay, China. In spring, the phytoplankton community structure was similar among the three stations, and was mainly composed of nanophytoplankton, such as, Skeletonema costatum and Cylindrotheca closterium. The structure became significantly different for the three stations in summer, when the dominant species at Stas A, B and C were Chaetoceros curvisetus, Pseudo-nitzschia delicatissima, C. affinis, C. debilis, Coscinodiscus oculus-iridis and Paralia sulcata respectively. Tintinnopsis beroidea and T. tsingtaoensis were the dominant species in spring, whereas the microzooplankton was apparently dominated by Strombidium sp. in summer. Pico- and nanophytoplankton had a relatively greater growth rate than microzooplankton both in spring and summer. The growth rate and grazing mortality rate were 0.18~0.44 and 0.12~1.47 d-1 for the total phytoplankton and 0.20~0.55 and 0.21~0.37 d-1 for nanophytoplankton in spring respectively. In summer, the growth rate and grazing mortality rate were 0.38~0.71 and 0.27~0.60 d-1 for the total phytoplankton and 0.11~1.18 and 0.41~0.72 d-1 for nano- and microphytoplankton respectively. The carbon flux consumed by microzooplankton per day was 7.68~39.81 mg/m3 in spring and 12.03~138.22 mg/m3 in summer respectively. Microzooplankton ingested 17.56%~92.19% of the phytoplankton standing stocks and 31.77%~467.88% of the potential primary productivity in spring; in contrast, they ingested 34.60%~83.04% of the phytoplankton standing stocks and 71.28%~98.80% of the potential primary productivity in summer. Pico- and nanophytoplankton appeared to have relatively greater rates of growth and grazing mortality than microphytoplankton during the experimental period. The grazing rate of microzooplankton in summer was a little bit greater than that in spring because of the relatively higher incubation temperature and different dominant microzooplankton species. Microzooplankton preferred ingesting nanophytoplankton to microphytoplankton in spring, while they preferred ingesting picophytoplankton to nanophytoplankton and microphytoplankton in summer. Compared with the results of dilution experiments performed in various waters worldwide, the results are in the middle range.展开更多
Phytoplankton group-specific growth and microzooplankton grazing were determined seasonally using the dilution technique with high-performance liquid chromatography （HPLC） in the Xiamen Bay, a subtropical bay in sou...Phytoplankton group-specific growth and microzooplankton grazing were determined seasonally using the dilution technique with high-performance liquid chromatography （HPLC） in the Xiamen Bay, a subtropical bay in southeast China, between May 2003 and February 2004. The results showed that growth rates of phytoplankton ranged from 0.71 to 2.2 d^-1 with the highest value occurred in the inner bay in May. Mierozooplankton grazing rates ranged from 0.5 to 3.1 d^-1 with the highest value occurred in the inner bay in August. Microzooplankton grazing impact ranged from 39% to 95% on total phytoplankton Chl a biomass, and 65% to 181% on primary production. The growth and grazing rates of each phytoplankton group varied, the highest growth rate （up to 3.3 d^-1 ） was recorded for diatoms in August, while the maximum grazing rate （ up to 2.1 d ^-1 ） was recorded for chlorophytes in February in the inner bay. Among main phytoplankton groups, grazing pressure of microzooplankton ranged from 10% to 83% on Chl a biomass, and from 14% to 151% on primary production. The highest grazing pressure on biomass was observed for cryptophytes （83%） in August, while the maximum grazing pressure on primary production was observed for eyanobacteria （up to 151% ） in December in the inner bay. Net growth rates of larger phytoplanktons （diatoms and dinoflagellates） were higher than those of smaller groups （ prasinophytes, chlorophytes and cyanobacteria）. Relative preference index showed that microzooplankton grazed preferentially on prasinophytes and avoided to harvest diatoms in cold seasons （December and February）.展开更多
Phytoplankton growth rates and mortality rates were experimentally examined at 21 stations during the 2017 spring intermonsoon(April to early May)in the northern and central South China Sea(SCS)using the dilution tech...Phytoplankton growth rates and mortality rates were experimentally examined at 21 stations during the 2017 spring intermonsoon(April to early May)in the northern and central South China Sea(SCS)using the dilution technique,with emphasis on a comparison between the northern and central SCS areas which had different environmental factors.There had been higher temperature but lower nutrients and chlorophyll a concentrations in the central SCS than those in the northern SCS.The mean rates of phytoplankton growth(μ0)and microzooplankton grazing(m)were(0.88±0.33)d–1 and(0.55±0.22)d–1 in the central SCS,and both higher than those in the northern SCS with the values ofμ0((0.81±0.16)d–1)and m((0.30±0.09)d–1),respectively.Phytoplankton growth and microzooplankton grazing rates were significantly coupled in both areas.The microzooplankton grazing impact(m/μ0)on phytoplankton was also higher in the central SCS(0.63±0.12)than that in the northern SCS(0.37±0.06).The microzooplankton abundance was significantly correlated with temperature in the surface.Temperature might more effectively promote the microzooplankton grazing rate than phytoplankton growth rate,which might contribute to higher m and m/μ0 in the central SCS.Compared with temperature,nutrients mainly affected the growth rate of phytoplankton.In the nutrient enrichment treatment,the phytoplankton growth rate(μn)was higher thanμ0 in the central SCS,suggesting phytoplankton growth in the central SCS was nutrient limited.The ratio ofμ0/μn was significantly correlated with nutrients concentrations in the both areas,indicating the limitation of nutrients was related to the concentrations of background nutrients in the study stations.展开更多
The species composition and abundance of microzooplankton at 10 marine and five coastal stations(Hongdao,Daguhe,Haibohe,Huangdao and Hangxiao) in the Jiaozhou Bay(Qingdao,China) were studied in 2001.The microzooplankt...The species composition and abundance of microzooplankton at 10 marine and five coastal stations(Hongdao,Daguhe,Haibohe,Huangdao and Hangxiao) in the Jiaozhou Bay(Qingdao,China) were studied in 2001.The microzooplankton community was found to be dominated by Tintinnopsis beroidea,Tintinnopsis urnula,Tintinnopsis brevicollis and Codonellopsis sp.The average abundance of microzooplankton was highly variable among stations.Specifically,the abundance of microzooplankton was higher at inshore stations and lower in the center of the bay(St.5),bay mouth(St.9) and outside the bay(St.10).The highest average annual densities(346 ind./L) was observed at St.3,while the lowest(55 ind./L) was at St.10.Two abundance peaks were recorded in May(324 ind./L) and February(300 ind./L).The distribution of microzooplankton in three sampling layers at the 10 stations was relatively homogenous and the abundance decreased slightly as the water depth increased.At coastal stations,the highest average annual density was recorded at Hongdao Station(677 ind./L),followed by Daguhe Station(616 ind./L),Haibohe Station(400 ind./L),Huangdao Station(275 ind./L) and Hangxiao Station(73 ind./L).Furthermore,a 24-h sampling analysis conducted at Hangxiao Station revealed that the microzooplankton assemblages were characterized by a bimodal diel vertical migration pattern,with the highest densities occurring at dusk(154 ind./L),followed by dawn(146 ind./L),noon(93 ind./L) and midnight(77 ind./L).The density of microzooplankton in the Jiaozhou Bay was in the middle range of the densities of temperate coastal waters worldwide.展开更多
Dilution incubations and Calanus sinicus addition incubations were simultaneously conducted at five stations in the Yellow Sea in June of 2004 to evaluate the impact of microzooplankton and Calanus sinicus on phytopla...Dilution incubations and Calanus sinicus addition incubations were simultaneously conducted at five stations in the Yellow Sea in June of 2004 to evaluate the impact of microzooplankton and Calanus sinicus on phytoplankton based on the Chlorophyll a(Chl-a) levels.The Chl-a growth rates(k) ranged from 0.60-1.67 d-1,while microzooplankton grazed the Chl-a at rates(g) of 0.29-0.62 d-1.The addition of C.sinicus enhanced the Chl-a growth rate(Z) by 0.004-0.037 d-1 ind.-1 L.C.sinicus abundance ranged from 84.1-160.9 ind.m-3,which occupied 90.7%-99.1% of the copepod(>500 μm) population.The in-situ increase in phytoplankton by C.sinicus community was estimated to be 0.000 4-0.005 9 d-1.These results showed that microzooplankton were the main grazers of phytoplankton,while C.sinicus induced a slight increase in the levels of phytoplankton.展开更多
Preliminary studies on microzooplankton grazing were conducted with dilution method in Jiaozhou Bay from summer 1998 to spring 1999. Four experiments were carried out at St.5 located at the center of Jiaozhou Bay. Chl...Preliminary studies on microzooplankton grazing were conducted with dilution method in Jiaozhou Bay from summer 1998 to spring 1999. Four experiments were carried out at St.5 located at the center of Jiaozhou Bay. Chlorophyll a concentrations were consistently dominated by netphytoplankton(net-,>20μm), except during the autumn 1998 cruise, when they were dominated by nanophytoplankton(nano-,2-20μm). The contribution of picophytoplankton (pico-,<2μm) to total chlorophyll a concentrations(<200μm) varied considerably between cruises. Instantaneous growth coefficients(u) of phytoplankton varied from 0.098 to 1.947d -1 , with mean value of 0.902d -1 . Instantaneous coefficients(g) of microzooplankton grazing on phytoplankton ranged from 0.066 to 0.567d -1 , mean value of 0.265d -1 , which was equivalent to daily loss of 21.9% of the initial standing stock and 58.1% of the daily potential production.展开更多
Assessment of microzooplankton and copepods grazing pressure on picoplankton is a key requirement for resolving the microbial food web efficiency.Although microzooplankton grazing on picoplankton has been extensively ...Assessment of microzooplankton and copepods grazing pressure on picoplankton is a key requirement for resolving the microbial food web efficiency.Although microzooplankton grazing on picoplankton has been extensively studied,the impact of microzooplankton on different groups of picoplankton,i.e.,heterotrophic bacteria,Synechococcus and picoeukaryotes have rarely been compared.Furthermore,in the very few existing studies there is no consistent evidence of an enhancing or restraining effect of copepods on picoplankton.More studies are needed to improve our understanding of the influence of microzooplankton and copepod on picoplankton.Dilution incubations and copepod addition incubations were performed during a cruise to the southern Yellow Sea on May 16-29,2007.The bulk grazing of microzooplankton and the calanoid copepod Cal anus sinicus on phytoplankton,flagellates and picoplankton was estimated.Stations were divided into either eutrophic or oligotrophic according to the nutrient and biological parameters.Picoplankton comprised a large part of the diet of microzooplankton in the central oligotrophic area,while phytoplankton was the main food of microzooplankton in the coastal eutrophic area.In the central oligotrophic area,microzooplankton preferred grazing on Synechococcus.After copepod addition,ciliate abundance decreased while Synechococcus abundance increased(382%,64%and 64%at three experimental stations,respectively),indicating strong grazing pressure of microzooplankton on Synechococcus.Our results suggest that Synechococcus might be an essential carbon source the planktonic food web in the oligotrophic waters of southern Yellow Sea.展开更多
基金supported by the National Natural Science Foundation of China under contract Nos 40206020 and 40306025the National Fundamental Rescarch Program of China under contract No.2001CB409702.
文摘Dilution experiments were performed to examine the growth rate and grazing mortality rate of size-fractionated phytoplankton at three typical stations, inside and outside the bay, in the spring and summer of 2003 in the Jiaozhou Bay, China. In spring, the phytoplankton community structure was similar among the three stations, and was mainly composed of nanophytoplankton, such as, Skeletonema costatum and Cylindrotheca closterium. The structure became significantly different for the three stations in summer, when the dominant species at Stas A, B and C were Chaetoceros curvisetus, Pseudo-nitzschia delicatissima, C. affinis, C. debilis, Coscinodiscus oculus-iridis and Paralia sulcata respectively. Tintinnopsis beroidea and T. tsingtaoensis were the dominant species in spring, whereas the microzooplankton was apparently dominated by Strombidium sp. in summer. Pico- and nanophytoplankton had a relatively greater growth rate than microzooplankton both in spring and summer. The growth rate and grazing mortality rate were 0.18~0.44 and 0.12~1.47 d-1 for the total phytoplankton and 0.20~0.55 and 0.21~0.37 d-1 for nanophytoplankton in spring respectively. In summer, the growth rate and grazing mortality rate were 0.38~0.71 and 0.27~0.60 d-1 for the total phytoplankton and 0.11~1.18 and 0.41~0.72 d-1 for nano- and microphytoplankton respectively. The carbon flux consumed by microzooplankton per day was 7.68~39.81 mg/m3 in spring and 12.03~138.22 mg/m3 in summer respectively. Microzooplankton ingested 17.56%~92.19% of the phytoplankton standing stocks and 31.77%~467.88% of the potential primary productivity in spring; in contrast, they ingested 34.60%~83.04% of the phytoplankton standing stocks and 71.28%~98.80% of the potential primary productivity in summer. Pico- and nanophytoplankton appeared to have relatively greater rates of growth and grazing mortality than microphytoplankton during the experimental period. The grazing rate of microzooplankton in summer was a little bit greater than that in spring because of the relatively higher incubation temperature and different dominant microzooplankton species. Microzooplankton preferred ingesting nanophytoplankton to microphytoplankton in spring, while they preferred ingesting picophytoplankton to nanophytoplankton and microphytoplankton in summer. Compared with the results of dilution experiments performed in various waters worldwide, the results are in the middle range.
基金The National Natural Science Foundatisn of China under contract Nos 40730846 and 40521003the National Basic Key Research Program of the Ministry of Science and Technology of China (China GLOBEC-IMBER Program) under contract No.2006CB400604
文摘Phytoplankton group-specific growth and microzooplankton grazing were determined seasonally using the dilution technique with high-performance liquid chromatography （HPLC） in the Xiamen Bay, a subtropical bay in southeast China, between May 2003 and February 2004. The results showed that growth rates of phytoplankton ranged from 0.71 to 2.2 d^-1 with the highest value occurred in the inner bay in May. Mierozooplankton grazing rates ranged from 0.5 to 3.1 d^-1 with the highest value occurred in the inner bay in August. Microzooplankton grazing impact ranged from 39% to 95% on total phytoplankton Chl a biomass, and 65% to 181% on primary production. The growth and grazing rates of each phytoplankton group varied, the highest growth rate （up to 3.3 d^-1 ） was recorded for diatoms in August, while the maximum grazing rate （ up to 2.1 d ^-1 ） was recorded for chlorophytes in February in the inner bay. Among main phytoplankton groups, grazing pressure of microzooplankton ranged from 10% to 83% on Chl a biomass, and from 14% to 151% on primary production. The highest grazing pressure on biomass was observed for cryptophytes （83%） in August, while the maximum grazing pressure on primary production was observed for eyanobacteria （up to 151% ） in December in the inner bay. Net growth rates of larger phytoplanktons （diatoms and dinoflagellates） were higher than those of smaller groups （ prasinophytes, chlorophytes and cyanobacteria）. Relative preference index showed that microzooplankton grazed preferentially on prasinophytes and avoided to harvest diatoms in cold seasons （December and February）.
基金The National Key Research and Development Program of China under contract No.2019YFC1407805the National Natural Science Foundation of China under contract Nos 41876134 and 41676112+2 种基金the University Innovation Team Training Program for Tianjin under contract No.TD12-5003the Tianjin 131 Innovation Team Program under contract No.20180314the Changjiang Scholar Program of Chinese Ministry of Education to Jun Sun under contract No.T2014253。
文摘Phytoplankton growth rates and mortality rates were experimentally examined at 21 stations during the 2017 spring intermonsoon(April to early May)in the northern and central South China Sea(SCS)using the dilution technique,with emphasis on a comparison between the northern and central SCS areas which had different environmental factors.There had been higher temperature but lower nutrients and chlorophyll a concentrations in the central SCS than those in the northern SCS.The mean rates of phytoplankton growth(μ0)and microzooplankton grazing(m)were(0.88±0.33)d–1 and(0.55±0.22)d–1 in the central SCS,and both higher than those in the northern SCS with the values ofμ0((0.81±0.16)d–1)and m((0.30±0.09)d–1),respectively.Phytoplankton growth and microzooplankton grazing rates were significantly coupled in both areas.The microzooplankton grazing impact(m/μ0)on phytoplankton was also higher in the central SCS(0.63±0.12)than that in the northern SCS(0.37±0.06).The microzooplankton abundance was significantly correlated with temperature in the surface.Temperature might more effectively promote the microzooplankton grazing rate than phytoplankton growth rate,which might contribute to higher m and m/μ0 in the central SCS.Compared with temperature,nutrients mainly affected the growth rate of phytoplankton.In the nutrient enrichment treatment,the phytoplankton growth rate(μn)was higher thanμ0 in the central SCS,suggesting phytoplankton growth in the central SCS was nutrient limited.The ratio ofμ0/μn was significantly correlated with nutrients concentrations in the both areas,indicating the limitation of nutrients was related to the concentrations of background nutrients in the study stations.
基金Supported by the Knowledge Innovation Project of Chinese Academy of Sciences (No KZCX2-403)a Joint Project of the Natural Science Foundation of China and Guangdong Province (No U0633006)
文摘The species composition and abundance of microzooplankton at 10 marine and five coastal stations(Hongdao,Daguhe,Haibohe,Huangdao and Hangxiao) in the Jiaozhou Bay(Qingdao,China) were studied in 2001.The microzooplankton community was found to be dominated by Tintinnopsis beroidea,Tintinnopsis urnula,Tintinnopsis brevicollis and Codonellopsis sp.The average abundance of microzooplankton was highly variable among stations.Specifically,the abundance of microzooplankton was higher at inshore stations and lower in the center of the bay(St.5),bay mouth(St.9) and outside the bay(St.10).The highest average annual densities(346 ind./L) was observed at St.3,while the lowest(55 ind./L) was at St.10.Two abundance peaks were recorded in May(324 ind./L) and February(300 ind./L).The distribution of microzooplankton in three sampling layers at the 10 stations was relatively homogenous and the abundance decreased slightly as the water depth increased.At coastal stations,the highest average annual density was recorded at Hongdao Station(677 ind./L),followed by Daguhe Station(616 ind./L),Haibohe Station(400 ind./L),Huangdao Station(275 ind./L) and Hangxiao Station(73 ind./L).Furthermore,a 24-h sampling analysis conducted at Hangxiao Station revealed that the microzooplankton assemblages were characterized by a bimodal diel vertical migration pattern,with the highest densities occurring at dusk(154 ind./L),followed by dawn(146 ind./L),noon(93 ind./L) and midnight(77 ind./L).The density of microzooplankton in the Jiaozhou Bay was in the middle range of the densities of temperate coastal waters worldwide.
基金Supported by the National Natural Science Foundation of China(No.40876085),the National Natural Science Foundation of China(No.40821004)the National Basic Research Program of China(973 Program)(No.2006CB400604)the Knowledge Innovation Program of Chinese Academy of Sciences(No.KZCX2-YW-213-3)
文摘Dilution incubations and Calanus sinicus addition incubations were simultaneously conducted at five stations in the Yellow Sea in June of 2004 to evaluate the impact of microzooplankton and Calanus sinicus on phytoplankton based on the Chlorophyll a(Chl-a) levels.The Chl-a growth rates(k) ranged from 0.60-1.67 d-1,while microzooplankton grazed the Chl-a at rates(g) of 0.29-0.62 d-1.The addition of C.sinicus enhanced the Chl-a growth rate(Z) by 0.004-0.037 d-1 ind.-1 L.C.sinicus abundance ranged from 84.1-160.9 ind.m-3,which occupied 90.7%-99.1% of the copepod(>500 μm) population.The in-situ increase in phytoplankton by C.sinicus community was estimated to be 0.000 4-0.005 9 d-1.These results showed that microzooplankton were the main grazers of phytoplankton,while C.sinicus induced a slight increase in the levels of phytoplankton.
文摘Preliminary studies on microzooplankton grazing were conducted with dilution method in Jiaozhou Bay from summer 1998 to spring 1999. Four experiments were carried out at St.5 located at the center of Jiaozhou Bay. Chlorophyll a concentrations were consistently dominated by netphytoplankton(net-,>20μm), except during the autumn 1998 cruise, when they were dominated by nanophytoplankton(nano-,2-20μm). The contribution of picophytoplankton (pico-,<2μm) to total chlorophyll a concentrations(<200μm) varied considerably between cruises. Instantaneous growth coefficients(u) of phytoplankton varied from 0.098 to 1.947d -1 , with mean value of 0.902d -1 . Instantaneous coefficients(g) of microzooplankton grazing on phytoplankton ranged from 0.066 to 0.567d -1 , mean value of 0.265d -1 , which was equivalent to daily loss of 21.9% of the initial standing stock and 58.1% of the daily potential production.
文摘Assessment of microzooplankton and copepods grazing pressure on picoplankton is a key requirement for resolving the microbial food web efficiency.Although microzooplankton grazing on picoplankton has been extensively studied,the impact of microzooplankton on different groups of picoplankton,i.e.,heterotrophic bacteria,Synechococcus and picoeukaryotes have rarely been compared.Furthermore,in the very few existing studies there is no consistent evidence of an enhancing or restraining effect of copepods on picoplankton.More studies are needed to improve our understanding of the influence of microzooplankton and copepod on picoplankton.Dilution incubations and copepod addition incubations were performed during a cruise to the southern Yellow Sea on May 16-29,2007.The bulk grazing of microzooplankton and the calanoid copepod Cal anus sinicus on phytoplankton,flagellates and picoplankton was estimated.Stations were divided into either eutrophic or oligotrophic according to the nutrient and biological parameters.Picoplankton comprised a large part of the diet of microzooplankton in the central oligotrophic area,while phytoplankton was the main food of microzooplankton in the coastal eutrophic area.In the central oligotrophic area,microzooplankton preferred grazing on Synechococcus.After copepod addition,ciliate abundance decreased while Synechococcus abundance increased(382%,64%and 64%at three experimental stations,respectively),indicating strong grazing pressure of microzooplankton on Synechococcus.Our results suggest that Synechococcus might be an essential carbon source the planktonic food web in the oligotrophic waters of southern Yellow Sea.
