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1.
River discharge can deliver nutrients to the coastal zone and change the hydrologic properties of the water column. Soon after a flash flood from the Yalu River (Northeast China) in August 2010, we investigated the salinity and nutrient concentrations, as well as other environmental conditions in the Changshan Archipelago area, located approximately 100 km west of the river mouth in the northern Yellow Sea. Diluted water was mainly observed in the upper layers shallower than 15 m, with surface salinity between 18.13 and 30.44 in the eastern study area and between 28.16 and 29.72 in the western area. Surface salinity showed a significant negative correlation with concentrations of dissolved nutrients (P < 0.05), but not with that of Chlorophyll-a (Chl-a), dissolved oxygen (DO), particulate materials or pH. The average concentrations of nitrite, nitrate, and silicic acid decreased from the surface layer to bottom layer and were significantly higher in the east area than in the west area (P < 0.05). In contrast, average ammonium and phosphate concentrations were highest in the bottom layer of both areas, with no significant spatial differences. DO varied between 6.06 and 8.25 mg L-1 in the surface layer, and was significantly higher in the eastern area than in the western area in the surface and middle layers. Chl-a concentration was constantly below 4.09 μg L-1. Our work demonstrated the strong influences of Yalu River on proportions of various nutrient components in the Changshan Archipelago area. Silicic acid and total inorganic nitrogen levels were significantly elevated comparing to phosphate in the eastern area. Such changes can potentially induce phosphate limit to phytoplankton growth.  相似文献   

2.
The Yellow Sea Cold Water Mass （YSCWM） was suggested as an over-summering site of the dominant copepod species Calanus sinicus in coastal Chinese seas. Population abundance and structure were investigated by monthly sampling along three transects across the northern boundary of the YSCWM during 2009-2010. Results show that thermal stratification existed from June to October and that the vertical thermal difference increased with depth. Generally, total abundance was lowest in October and highest in June, and the female/male sex ratio was highest in February and lowest in August. Evident spatial differences in abundance were observed during the existence of the YSCWM. In June, total abundance averaged 158.8 ind/m~ at well-stratified stations, and 532.1 ind/m3 at other stations. Similarly, high abundances of 322.0 and 324.4 ind/m3 were recorded from July to August inside the YSCWM, while the abundance decreased from 50.4 to 1.9 ind/m3 outside the water mass. C. sinicus distribution tended to even out over the study area in September when the YSCWM disappeared. We believe that the YSCWM may retard population recruitment in spring and preserve abundant cohorts in summer. The summer population was transported to neritic waters in autumn. In addition to low temperatures, stable vertical structure was also an essential condition for preservation of the summer population. C. sinicus can survive the summer in marginal areas in high abundance, but the population structure is completely different in terms of C5 proportion and sex ratio.  相似文献   

3.
Using a three-dimensional coupled biophysical model,we simulated the responses of a lowtrophic ecosystem in the East China Sea(ECS)to long-term changes in nutrient load from the Changjiang(Yangtze)River over the period of 1960–2005.Two major factors aff ected changes in nutrient load:changes in river discharge and the concentration of nutrients in the river water.Increasing or decreasing Changjiang discharge induced different responses in the concentrations of nutrients,phytoplankton,and detritus in the ECS.Changes in dissolved inorganic nitrogen(DIN),silicate(SIL),phytoplankton,and detritus could be identified over a large area of the ECS shelf,but changes in dissolved inorganic phosphate(DIP)were limited to a small area close to the river mouth.The high DIN:DIP and SIL:DIP ratios in the river water were likely associated with the diff erent responses in DIN,DIP,and SIL.As DIP is a candidate limiting nutrient,perturbations in DIP resulting from changes in the Changjiang discharge are quickly consumed through primary production.It is interesting that an increase in the Changjiang discharge did not always lead to an increase in phytoplankton levels in the ECS.Phytoplankton decreases could be found in some areas close to the river mouth.A likely cause of the reduction in phytoplankton was a change in the hydrodynamic field associated with the river plume,although the present model is not suitable for examining the possibility in detail.Increases in DIN and DIP concentrations in the river water primarily led to increases in DIN,DIP,phytoplankton,and detritus levels in the ECS,whereas decreases in the SIL concentration in river water led to lower SIL concentrations in the ECS,indicating that SIL is not a limiting nutrient for photosynthesis,based on our model results from 1960 to 2005.In both of the above-mentioned cases,the sediment accumulation rate of detritus exhibited a large spatial variation near the river mouth,suggesting that core sample data should be carefully interpreted.  相似文献   

4.
A cruise was undertaken from 3rd to 8th November 2004 in Changjiang （Yangtze） River Estuary and its adjacent waters to investigate the spatial biomass distribution and size composition of phytoplankton. Chlorophyll-a （Chl-a） concentration ranged 0.42-1.17 μg L^-1 and 0.41-10.43 μg L^-1 inside and outside the river mouth, with the mean value 0.73 μg L^-1 and 1.86 μg L^-1, respectively. Compared with the Chl-a concentration in summer of 2004, the mean value was much lower inside, and a little higher outside the river mouth. The maximal Chl-a was 10.43 μg L^-1 at station 18 （122.67°E, 31.25°N）, and the region of high Chl-a concentration was observed in the central survey area between 122.5°E and 123.0°E. In the stations located east of 122.5°E, Chl-a concentration was generally high in the upper layers above 5 m due to water stratification. In the survey area, the average Chl-a in sizes of 〉20 μm and 〈20 μm was 0.28 μg L^-1 and 1.40 μg L^-1, respectively. High Chl-a concentration of 〈20 μm size-fraction indicated that the nanophytoplankton and picophytoplankton contributed the most to the biomass of phytoplankton. Skeletonema costatum, Prorocentrum micans and Scrippsiella trochoidea were the dominant species in surface water. The spatial distribution of cell abundance of phytoplankton was patchy and did not agree well with that of Chl-a, as the cell abundance could not distinguish the differences in shape and size of phytoplankton cells. Nitrate and silicate behaved conservatively, but the former could probably be the limitation factor to algal biomass at offshore stations. The distribution of phosphate scattered considerably, and its relation to the phytoplankton biomass was complicated.  相似文献   

5.
The characteristics of seasonal variation in phytoplankton biomass and dominant species in the Changjiang River Estuary and adjacent seas were discussed based on field investigation data from 1959 to 2009. The field data from 1981 to 2004 showed that the Chlorophyll-a concentration in surface seawater was between 0.4 and 8.5 ktg dm-3. The seasonal changes generally presented a bimodal trend, with the biomass peaks occurring in May and August, and Chlorophyll-a concentration was the lowest in winter. Seasonal biomass changes were mainly controlled by temperature and nutrient levels. From the end of autumn to the next early spring, phytoplankton biomass was mainly influenced by temperature, and in other seasons, nutrient level （including the nutrient supply from the terrestrial runoffs） was the major influence factor. Field investigation data from 1959 to 2009 demonstrated that dia- toms were the main phytoplankton in this area, and Skeletonerna costatum, Pseudo-nitzschia pungens, Coscinodiscus oculus-iridis, Thalassinoema nitzschioides, Paralia sulcata, Chaetoceros lorenzianus, Chaetoceros curvisetus, and Prorocentrum donghaiense Lu were common dominant species. The seasonal variations in major dominant phytoplankton species presented the following trends： 1） Skeletonema （mainly S. costatum） was dominant throughout the year; and 2） seasonal succession trends were Coscinodiscus （spring） →Chaetoceros （summer and autumn） → Coscinodiscus （winter）. The annual dominance of S. costatum was attributed to its environmental eurytopicity and long standing time in surface waters. The seasonal succession of Coscinodiscus and Chaetoceros was associated with the seasonal variation in water stability and nutrient level in this area. On the other hand, long-term field data also indicated obvious interannual variation of phytoplankton biomass and community structure in the Changjiang River Estuary and adjacent seas： average annual phytoplankton biomass and dinoflagellate proportion both presented inc  相似文献   

6.
The chlorophyll a(Chl a) is an important indicator of marine ecosystems. The spatiotemporal variation of the Chl a greatly aff ects the mariculture and marine ranching in coastal waters of the Shandong Peninsula. In the current study, the climatology and seasonal variability of surface Chl-a concentration around the Shandong Peninsula are investigated based on 16 years(December 2002–November 2018) of satellite observations. The results indicate that the annual mean Chl-a concentration is greater in the Bohai Sea than in the Yellow Sea and decreases from coastal waters to off shore waters. The highest Chl-a concentrations are found in Laizhou Bay(4.2–8.0 mg/m 3), Haizhou Bay(4.2–5.9 mg/m 3) and the northeast coast of the Shandong Peninsula(4.4–5.0 mg/m 3), resulting from the combined eff ects of the intense riverine input and long residence time caused by the concave shape of the coastline. The seasonal Chl-a concentration shows a signifi cant spatial variation. The Chl-a concentrations in these three subregions generally exhibit an annual maximum in August/September, due to the combined eff ects of sea surface temperature, river discharge and sea surface wind. In the southeast coast region, however, the Chl-a concentration is lowest throughout the year and reaches a maximum in February with a minimum in July, forced by the seasonal evolution of the Yellow Sea Cold Water and monsoon winds. The interannual Chl-a concentration trends vary among regions and seasons. There are signifi cant increasing trends over a large area around Haizhou Bay from winter to summer, which are mainly caused by the rising sea surface temperature and eutrophication. In other coastal areas, the Chl-a concentration shows decreasing trends, which are clearest in summer and induced by the weakening land rainfall. This study highlights the diff erences in the Chl-a dynamics among regions around the Shandong Peninsula and is helpful for further studies of coupled physical-ecological-human interactions at multiple scales.  相似文献   

7.
The increasing riverine pollutants have resulted in nutrient enrichment and deterioration of water quality in the coastal water of Guangxi Province, China. However, the quantitative relationship between nutrient loads and water quality responses, which is crucial for developing eutrophication control strategies, is not well studied. In this study, the riverine fluxes of nutrients were quan- tified and integrated with nutrient cycling and phytoplankton dynamics by using box models for Guangxi coastal bays. The model concepts and biogeochemical equations were the same; while most model parameters were specific for each bay. The parameters were calibrated with seasonal observations during 2006--2007, and validated with yearly averaged measurements in 2009. The gen-eral features of nutrient and phytoplankton dynamics were reproduced, and the models were proved feasible under a wide range of bay conditions. Dissolved inorganic nitrogen was depleted during the spring algal bloom in Zhenzhu Bay and Fangcheng Bay with relatively less nutrient inputs. Phosphorus concentration was high in spring, which decreased then due to continuous phytoplankton consumption. Chlorophyll-a concentration reached its annual maximum in summer, but was the minimum in winter. Eutrophication was characterized by both an increase in nutrient concentrations and phytoplankton biomass in Lianzhou Bay. Either about 80% re-duction of nitrogen or 70% reduction of phosphorus was required to control the algal bloom in Lianzhou Bay. Defects of the models were discussed and suggestions to the environmental protection of Guangxi coastal bays were proposed.  相似文献   

8.
The increasing riverine pollutants have resulted in nutrient enrichment and deterioration of water quality in the coastal water of Guangxi Province, China. However, the quantitative relationship between nutrient loads and water quality responses, which is crucial for developing eutrophication control strategies, is not well studied. In this study, the riverine fluxes of nutrients were quantified and integrated with nutrient cycling and phytoplankton dynamics by using box models for Guangxi coastal bays. The model concepts and biogeochemical equations were the same; while most model parameters were specific for each bay. The parameters were calibrated with seasonal observations during 2006–2007, and validated with yearly averaged measurements in 2009. The general features of nutrient and phytoplankton dynamics were reproduced, and the models were proved feasible under a wide range of bay conditions. Dissolved inorganic nitrogen was depleted during the spring algal bloom in Zhenzhu Bay and Fangcheng Bay with relatively less nutrient inputs. Phosphorus concentration was high in spring, which decreased then due to continuous phytoplankton consumption. Chlorophyll-a concentration reached its annual maximum in summer, but was the minimum in winter. Eutrophication was characterized by both an increase in nutrient concentrations and phytoplankton biomass in Lianzhou Bay. Either about 80% reduction of nitrogen or 70% reduction of phosphorus was required to control the algal bloom in Lianzhou Bay. Defects of the models were discussed and suggestions to the environmental protection of Guangxi coastal bays were proposed.  相似文献   

9.
Nutrient enrichment experiments with nitrogen （N） and phosphorus （P） were conducted with samples from two stationsin the coastal waters of Qingdao, China, during summer to identify limiting nutrients. In late July of 2009, low P concentrations andthe maximum photochemical efficiency of photosystem II （Fv/Fm） in the initial samples together with Fv/Fm and chlorophyll a （Chl a）responses to P addition indicated P limitation at the two stations. In early August, low P levels still limited phytoplankton growth atstation A. Fv/Fm and Chl a were the highest in the NP treatments at station B, suggesting an N/P co-limitation. In mid-September,nutrient concentrations and Fv/Fm were elevated and phytoplankton communities were healthy. Greater Fv/Fm and Chl a in the treat-ments with added P than those without the addition suggested potential P limitation at station A. Lack of Fv/Fm and Chl a responsesfollowing nutrient additions indicated N and P repletion at station B. At the end of July 2010, neither N nor P was limited at station B.Additionally, Fv/Fm coupled with 24-h-long nutrient enrichment experiments can be used to detect P limitation and N/P co-limitationto natural populations. This method can be more accurate for assessing co-limitation than the use of criteria of nutrient concentrationsand ratios as indicators, and can provide more rapid results than nutrient addition bioassays using chlorophyll response as an indica-tor, when a population is potentially limited. Compared with the two conventional methods, the results based on F,/F~ can also pro-vide more detailed information about physiological states of the populations.  相似文献   

10.
The environmental problems in the Bohai Sea have become more serious in the last decade. High nutrient concentration contributes much to it. A Sino-German cooperation program has been carried out to improve the understanding of the ecosystem by observations and modelling. A three-dimensional ecosystem model, coupled with a physical transport model, is adopted in this study. The simulation for the year 1982 is validated by the data collected in 1982/1983. The simulated annual mean nutrient concentrations are in good agreement with observations. The nutrient concentrations in the Bohai Sea, which are crucial to the algal growth, are high in winter and low in summer. There are depletion from spring to summer and eleva-tion from autumn to winter for nutrients. The nutrients‘ deple tion is a response to the consumption of the phytoplankton bloom in spring. Internal recycle and external compensation affect the nutrient cycle. Their contributions to the nutrient budgets are discussed based on the simulated results. Production and respiration are the most important sink and source of nutrients. The process of photosynthesis consumes 152 kilotons-P and 831.1 kilotons-N while respiration releases 94.5 kilotons-P and 516.6 kilotons-N in the same period. The remineralization of the detritus pool is an important source of nutrient regeneration. It can compensate 23 percent of the nutrient consumed by the production process. The inputs of phosphates and nitrogen from rivers are 0.55 and 52.7 kilotons respectively. The net nutrient budget is 3.05 kilotons-P and 31.6 kilotons-N.  相似文献   

11.
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12.
Phytoplankton and environmental variables were measured monthly from July 2009 to August 2011 in the Maixi River from the estuary to Baihua Reservoir in the Maotiao River catchment,southwestern China,to understand phytoplankton community structure and environmental factors.The relationship between phytoplankton community structure and environmental factors including hydrological,meteorological,physical,and chemical variables were explored using multivariate analysis.A total of 81 taxa of phytoplankton were identified,which were mainly composed of chlorophyta,bacillariophyta,and cyanobacteria.The phytoplankton community was dominated by Pseudanabaena limnetica during summer and fall and by Cyclotella meneghiniana during winter and spring.The abundance of phytoplankton ranged from 0.24×104 cells/L to 33.45×106 cells/L,with the minimum occurring during February 2010 and the maximum during July 2009.The phytoplankton community was dominated mainly by cyanobacteria from April to September,and by bacillariophyta and pyrrophyta from October to March.Canonical correspondence analysis showed that temperature,pH values,and orthophosphate were the most important driving factors regulating the composition and dynamics of the phytoplankton community in the estuary.Cyanobacteria and euglenophyta abundance and biomass were affected mainly by temperature and pH values,while most chlorophyta and bacillariophyta were influenced by the concentrations of nutrients.  相似文献   

13.
To solve nutrient flux and budget among waters with distinct salinity difference for water-saltnutrient budget,a traditional method is to build a stoichiometrically linked steady state model.However,the traditional way cannot cope appropriately with those without distinct salinity difference that parallel to coastline or in a complex current system,as the results would be highly affected by box division in time and space,such as the Changjiang(Yangtze) River estuary(CRE) and adjacent waters(30.75°-31.75°N,122°10′-123°20′E).Therefore,we developed a hydrodynamic box model based on the traditional way and the regional oceanic modeling system model(ROMS).Using data from four cruises in 2005,horizontal,vertical and boundary nutrient fluxes were calculated in the hydrodynamic box model,in which flux fields and the major controlling factors were studied.Results show that the nutrient flux varied greatly in season and space.Water flux outweighs the nutrient concentration in horizontal flux,and upwelling flux outweighs upward diffusion flux in vertical direction(upwelling flux and upward diffusion flux regions overlap largely all the year).Vertical flux in spring and summer are much greater than that in autumn and winter.The maximum vertical flux for DIP(dissolved inorganic phosphate) occurs in summer.Additional to the fluxes of the Changjiang River discharge,coastal currents,the Taiwan Warm Current,and the upwelling,nutrient flux inflow from the southern Yellow Sea and outflow southward are found crucial to nutrient budgets of the study area.Horizontal nutrient flux is controlled by physical dilution and confined to coastal waters with a little into the open seas.The study area acts as a conveyer transferring nutrients from the Yellow Sea to the East China Sea in the whole year.In addition,vertical nutrient flux in spring and summer is a main source of DIP.Therefore,the hydrodynamic ROMS-based box model is superior to the traditional one in estimating nutrient fluxes in a complicated hydrodynamic current system and provides a modified box model approach to material flux research.  相似文献   

14.
The characteristics of seasonal variation in phytoplankton biomass and dominant species in the Changjiang River Estuary and adjacent seas were discussed based on field investigation data from 1959 to 2009. The field data from 1981 to 2004 showed that the Chlorophyll-a concentration in surface seawater was between 0.4 and 8.5 μg dm-3. The seasonal changes generally presented a bimodal trend, with the biomass peaks occurring in May and August, and Chlorophyll-a concentration was the lowest in winter. Seasonal biomass changes were mainly controlled by temperature and nutrient levels. From the end of autumn to the next early spring, phytoplankton biomass was mainly influenced by temperature, and in other seasons, nutrient level(including the nutrient supply from the terrestrial runoffs) was the major influence factor. Field investigation data from 1959 to 2009 demonstrated that diatoms were the main phytoplankton in this area, and Skeletonema costatum, Pseudo-nitzschia pungens, Coscinodiscus oculus-iridis, Thalassinoema nitzschioides, Paralia sulcata, Chaetoceros lorenzianus, Chaetoceros curvisetus, and Prorocentrum donghaiense Lu were common dominant species. The seasonal variations in major dominant phytoplankton species presented the following trends: 1) Skeletonema(mainly S. costatum) was dominant throughout the year; and 2) seasonal succession trends were Coscinodiscus(spring) →Chaetoceros(summer and autumn) → Coscinodiscus(winter). The annual dominance of S. costatum was attributed to its environmental eurytopicity and long standing time in surface waters. The seasonal succession of Coscinodiscus and Chaetoceros was associated with the seasonal variation in water stability and nutrient level in this area. On the other hand, long-term field data also indicated obvious interannual variation of phytoplankton biomass and community structure in the Changjiang River Estuary and adjacent seas: average annual phytoplankton biomass and dinoflagellate proportion both presented increased trends during the 1950 s-2000 s.  相似文献   

15.
Fu  Dongyang  Luan  Hong  Pan  Delu  Zhang  Ying  Wang  Li’an  Liu  Dazhao  Ding  Youzhuan  Li  Xue 《中国海洋湖沼学报》2016,34(4):871-884
This study investigated the ef fects of two typhoons(Nari and Wipha) on sea surface temperature(SST) and chlorophyll- a(Chl- a) concentration. Typhoons Nari and Wipha passed through the Yellow Sea on September 13, 2007 and the East China Sea(ECS) on September 16, 2007, respectively. The SST and Chl- a data were obtained from the Aqua/Terra MODIS and NOAA18, respectively, and the temperature and salinity in the southeast of the study area were observed in situ from Argo. The average SST within the study area dropped from 26.33°C on September 10 to a minimum of 22.79°C on September 16. Without the usual phenomenon of ‘right bias', the most striking response of SST was in the middle of the typhoons' tracks, near to coastal waters. Strong cooling of the upper layers of the water column was probably due to increased vertical mixing, discharge from the Changjiang River estuary, and heavy rainfall. During the typhoons, average Chl-a increased by 11.54% within the study area and by 21.69% in the off shore area near to the southeast ECS. From September 1 to 13, average Chl-a was only 0.10 mg/m~3 in the of fshore waters but it reached a peak of 0.17 mg/m~3 on September 18. This large increase in Chl-a concentration in of fshore waters might have been triggered by strong vertical mixing, upwelling induced by strong typhoons, and sedimentation and nutrient infl ux following heavy rainfall.  相似文献   

16.
A three-dimensional ecosystem model, using a PIC （Particle-In-Cell） method, is developed to reproduce the annual cycleand seasonal variation of nutrients and phytoplankton biomass in Laizhou Bay. Eight state variables, i.e., DIN （dissolved inorganicnitrogen）, phosphate, DON （dissolved organic nitrogen）, DOP （dissolved organic phosphorus）, COD （chemical oxygen demand）,chlorophyll-a （Chl-a）, detritus and the zooplankton biomass, are included in the model. The model successfully reproduces the ob-served temporal and spatial variations of nutrients and Chl-a biomass distributions in the bay. The nutrient concentrations are at highlevel in winter and at low level in summer. Double-peak structure of the phytoplankton （PPT） biomass exists in Laizhou Bay, corre-sponding to a spring and an autumn bloom respectively. Several numerical experiments are carried out to examine the nutrient limita-tion, and the importance of the discharges of the Yellow River and Xiaoqinghe River. Both DIN limitation and phosphate limitationexist in some areas of the bay, with the former being more significant than the latter. The Yellow River and Xiaoqinghe River are themain pollution sources of nutrients in Laizhou Bay. During the flood season, the algal growth is inhibited in the bay with the YellowRiver discharges being excluded in the experiment, while in spring, the algal growth is enhanced with the Xiaoqinghe River ex-cluded.  相似文献   

17.
Investigations from August, 1985 to July , 1986 showed that the high concentration area of PO4-P , SiO3-Si and NO3-N gradually reduced with the reduction of the area of the Changjiang River diluted water from summer, autumn to winter , and that the seasonal distributions and variations of the nutrients concentrations were mainly controlled by the river flow and were also related to the growth and decline of phytoplankton . The conservation of SiO3-Si and NO3-N in the estuary in the flood season was poorer than that in the dry season .. The behaviour of PO4-P in the estuary shows that aside from -biological removal, buffering of PCU-P is possible in the estuary . The highest monthly average concentrations and annual average concentrations in the river mouth were respectively 0.88 and 0.57 umol/L for PO4-P,191.5 and 96.2 umol/L for SiO3-Si, and 81.6 and 58.6 umol/L for NOs-N . The Changjiang's annual transports of PO4-P , SiO3-Si and NO3-N to the sea were about 1.4×104tons , 204.4×104 tons and 63.6×104  相似文献   

18.
We investigated the abundance of different picophytoplankton groups and the phytoplankton pigment ratio in relation to environmental factors such as nutrients and suspended solids along a salinity gradient in the Changjiang River Estuary. The average numbers of Synechococcus spp.(Syn) and picoeukaryotes(Euk) were(2.7 ±5.1) ×103 and(1.1±1.4) ×103 cells m L-1, respectively. Prochlorococcus spp.(Pro) was only found in the high-salinity brackish water with the concentration of 3.0×103 cells m L-1. Syn and Euk numbers both tended to increase offshore and Syn showed a larger variation in cell abundance than Euk. The contribution of picophytoplankton to total phytoplankton biomass increased with increasing salinity and decreasing nutrient concentrations from the estuary to the open ocean. The response of different picophytoplankton groups to environmental variables was different. Water temperature was more important in its control over Euk than over Syn, while nutrients were more important in their influence over Syn than over Euk. Phytoplankton pigment ratios were different in the three different ecological zones along the salinity gradient(i.e., freshwater zone with 0-5 range, fresh and saline water mixing zone with 5-20 range, and high-salinity brackish water zone with 20-32 range), where three different phytoplankton communities were discovered, suggesting that phytoplankton pigment ratios can be considered as a complementary indicator of phytoplankton community structure in the Changjiang River Estuary.  相似文献   

19.
Phytoplankton blooms occurring in the Jiangdong Reservoir of Jiulong River, Fujian Province, South China, are a potential source of contamination of the drinking water of Xiamen （Amoy） City. To understand the main factors governing phytoplankton composition and succession, we sampled phytoplankton and measured environmental parameters in the reservoir, weekly or biweekly from Jan. 2010 to Feb. 2012. We identified 123 species of phytoplankton from 7 phyla and 74 genera. The major phyla were Chlorophyta, Bacillariophyta, Cryptophyta, Cyanophyta, and Dinophyta. The main trend in the succession of phytoplankton was from prevalence of Cryptophyta-Bacillariophyta communities to those of Chlorophyta-Cyanophyta. High cell concentrations of Cryptophyta, predominantly Komma caudate, Cryptomonas marssonii, and Cryptomonas erosa, were present in winter, associated with low river discharge and cold water. Bacillariophyta, primarily Cyclotella meneghiniana, Aulacoseira granulata, and Aulacoseira granulata var. angustissima, dominated in early spring, coinciding with high turbulence and low irradiance. During early summer and autumn, Chlorophyta, comprising Scenedesmus quadricauda, Dictyosphaerium ehrenbergianum, and Pandorina sp. were prevalent during conditions of warmer water temperatures and low turbulence. Cyanophyta, with dominance ofPseudanabaena mucicola, Merismopedia tenuissima and Raphidiopsis sp. increased throughout the summer, coinciding with higher water temperatures and lower nutrient concentrations. Dinophyta content was occasionally high during winter and summer. Peridiniopsis penardii （Dinophyta） bloomed during winter 2009, with a persistently high biomass recorded into early spring. Canonical correspondence analysis indicated that phytoplankton communities were influenced by river discharge, irradiance, water temperature, and nutrient concentrations.  相似文献   

20.
The South China Sea(SCS), which is the largest marginal sea in the western tropical Pacific, plays an important role in regional climate change. However, the research on the phytoplankton community structure(PCS) response to the upwelling remains inadequate. In January 2014, the upwelling simulation experiment was performed in the western SCS. Results indicate that the nutrient-rich bottom water not only increased the total Chlorophyll a(Chl a) concentrations, but would potentially altered the PCS. Due to new nutrients added, microphytoplankton had more sensitivity response to nutrient uptake than other phytoplankton groups. The variation of nutrients induced by formation, weakening and disappearance of upwelling resulted in phytoplankton species succession from cyanophyta to bacillariophyta. It may be the leading factor of the changes in PCS and size-fractionated Chl a. The initial concentration of DIP less than 0.1 μmol L-1 could not sustain the phytoplankton growth. This indicates that phosphorus may be the limiting factor in the western SCS.  相似文献   

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