Table of Content

15 July 2003, Volume 14 Issue 7

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Preliminary analysis of the characteristics of red tide areas in Changjiang River estuary and its adjacent sea

ZHOU Mingjiang, YAN Tian, ZOU Jingzhong

2003, (7):  1031-1038. 

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A review was made on the main environmental characteristics such as currents and water body,diluted water and its turning direction,upwelling,front,nutrients and its sources and plankton community in the Changjiang River estuary and its adjacent sea areas which could affect the growth,migration,assembling,resting and competition of harmful algae to form red tides. Analyses were also conducted to reveal features of the red tides events recorded in this area in terms of time,location and causative species. Some preliminary results from recent cruises carried out in the investigated sea area,where red tides were frequently occurring,were introduced.

Distribution of dinoflagellate resting cysts in surface sediments from the Changjiang River estuary

WANG Zhaohui, Qi Yuzao

2003, (7):  1039-1043. 

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In order to understand the potential of algal blooms, surface sediments were collected from 12 stations in the Changjiang River estuary with longitude from 122? to 123.5癊and latitude from 29? to 32癗from April to May 2002 to investigate the distribution of dinoflagellate resting cysts. 29 different cyst morphotypes representing19 genera and 6 groups were identified.Among them, there were 11 autotrophic species and 18 heterotrophic ones. The number of species observed in each sample was low, and varied from 10 to 21. Cyst concentrations varied from 11.7 to 587 cysts per gram dry weight. Cyst concentrations and species diversity were higher in offshore areas,and increased from the west to the east, and from the north to the south within the studied area. Cysts of Alexandrium distributed widely in the Changjiang River estuary,with the maximum concentration of 40.4 cysts per gram dry weight. Cysts of harmful algal bloom causative species such as Alexandrium, Gymnodinium catenatum, Lingulodinium polyedra, Scrippsiellla trochoidea, Polykrikos kofoidii and P. schwartzii were also observed in this survey.

Species composition and ecological distribution of planktonic diatoms in the Changjiang River estuary during Spring

GAO Yahui, YU Qiubo, QI Yuzao, ZHOU Jingzhong, LU Douding, LI Yang, CHENG Changping

2003, (7):  1044-1048. 

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water samples were collected from 28 stations in typical regions where redtide frequently occurred in the Changjiang River estuary during Spring, 2002. In total, 80 diatom species and varieties belonging to 31 genera were identified, among which, genera with high species biodiversity included Coscinodiscus which contained 17 species and Pleurosigma which contained 8 species and varieties. Quantitative analysis of diatom cell density showed that Pseudo-nitzschia delicatissma (3.48×10³cells·L^-1, 28.54%),Melosira sulcata(1.43×10³cells·L^-1, 16.98%)and Pseudo-nitzschia pungens(0.71×10³cells·L^-1, 9.85%) were dominant species, which occurred at almost all stations. Higher cell density of Pseudo-nitzschia delicatissma and Pseudo-nitzschia pungens occurred at stations along123°E, while that of Melosira sulcata occurred at stations around Changjiang River at 31～32°N. The total diatom cell density ranged from 0.43×10³～23.3×10³cells·L^-1,with average of 4.61×10³cells·L^-1. At station DD15 located at 123°E and 30.5°N, the highest diatom cell density was found,which was 1.85×10⁴cells·L^-1 at surface water layer, and 2.33×10⁴cells·L^-1 at middle water layer (30m) respectively. Horizontally, the diatom cell density showed scattered distribution, while vertically,it was commonly higher at surface water layer than that at middle water layer.

Mesocosm experiment on competition between two HAB species in East China Sea

LI Ruixiang, ZHU Mingyuan, WANG Zongling, SHI Xiaoyong, CHEN Bingzhang

2003, (7):  1049-1054. 

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Skeletonema costatum and Prorocentrum dentatum are the two common HAB species in East China Sea, and Prorocentrum is more responsible for most HAB events in Spring since late 90's. The HAB caused by Skeletonema usually occurs from June to August. However, these two species will not bloom at the same time. Two mesocosm experiments were conducted in East China Sea in May 1998 and May 2002. In the experiment of May 1998, the cell number of Prorocentrum dentatum and Skeletonema costatum accounted for about 85% and 11% of total cell number of phytoplankton,respectively at the beginning of the experiment. In control mesocosm, Prorocentrum dentatum dominated the community during the whole experiment. In phosphate-enriched mesocosm, however, Skeletonema costatum showed a high competition capability. In May 2002, there were 4 bags in the mesocosm experiment. At the beginning of the experiment, the cell number of Prorocentrum dentatum accounted for 55～66 % of the total,and that of Skeletonema costatum accounted for 32～42 %. During the experiment, the growth of Skeletonema costatum was faster than that of Prorocentrum dentatum.On the 2nd day, the cell number of Skeletonema costatum exceeded that of Prorocentrum dentatum. It showed that under high nutrients conditions,Skeletonema costatum grew better than Prorocentrum dentatum,but under nutrients-limited conditions,Prorocentrum dentatum could survival better than Skeletonema costatum.

Distribution features of chlorophyll a and primary productivity in high frequency area of red tide in East China Sea during Spring

ZHOU Weihua, HUO Wenyi, YUAN Xiangcheng, YIN Kedong

2003, (7):  1055-1059. 

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The distributions of chlorophyll a and primary productivity were determined during April to May 2002 in the East China Sea. The results showed that the average concentration of chlorophyll a was 1.086 mg·m^-3 at surface layer,and that nano-and pico-phytoplankton (<20μm) dominated the phytoplankton biomass in this sea region during Spring (up to 64% of total chlorophyll a content). Ultra-phytoplankton (<5μm) consisted 27% of total phytoplankton biomass. Nutrients and feeding pressure of zooplankton affected the distribution of chlorophyll a and its size-fractionation. The average primary productivity was 10.091 mg·m^-3·h^-1,while that of red tide tracking stations R-03, RL-01 and RG-01 was 399.984 mg·m^-3·h^-1. Light and nutrients were the main factors affecting the distributions of chlorophyll a and primary productivity. The station DC-11 had a high concentration of phytoplankton biomass.The surface layer concentration of chlorophyll a and primary productivity were up to 9.082 mg·m^-3 and 128.79 mg·m^-3·h^-1, respectively,but the color of the seawater was normal.

Redescription of Prorocentrum donghaiense Lu and comparison with relevant Prorocentrum species

LU Douding, QI Yuzao, Jeanette Goebel, ZOU Jingzhong, GAO Yahui

2003, (7):  1060-1064. 

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In this paper,the detailed morphology of Prorocentrum donghaiense was studied.Taxonomic comparison was made between P.donghaiense and other relevant Prorocentrum species. The results suggested that distinct differences existed among them with respect to their conservative characteristics of morphology and cell sizes. This kind of discrepancy was far beyond that of individual variations within same species due to environmental factors. Therefore, the high biomass bloom-forming species in the East China Sea was not real Prorocentrum "dentatum" Stein, but P. donghaiense Lu that was re-described in the present paper.P. donghaiense appeared in the East China Sea,and P."dentatum" occurred in Japanese and Korean waters should be the same species.

Ecological characteristics of Prorocentrum dentatum and the cause of harmful algal bloom formation in China Sea

WANG Jinhui, HUANG Xiuqing

2003, (7):  1065-1069. 

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Large-scale harmful alga bloom (HAB) has been found in Changjiang River estuary and Zhoushan archipelago in recent three years, and the alga is Prorocentrum dentatum, which distributes in the sea areas with high salinity and (may) originates in outer sea area. Data from recent HAB rapid monitoring and ecological investigation were analyzed to study its ecological characteristics and forming inducement. The results showed that the most suitable temperature and salinity range for HAB forming was from 18℃ to 22℃ and from 21 to 31, respectively. The P. dentatum was motile and owned diurnal vertical migration bringing them the advantages in obtaining light and nutrients.Eutrophication was the preliminary condition, and water temperature,nitrate content, upwelling current,and strong competence on low phosphate environment were important to cause and maintain HAB.

Scanning electron-microscopic study on Prorocentrum dentatum from the East China Sea

LU Songhui, ZHANG Yuyu, CHEN Jufang

2003, (7):  1070-1072. 

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There is an argument whether the bloom causative species of the East China Sea is Prorocentrum dentatum or a new species. Based on the scanning electron-microscopic study, we compared the detailed surface structure of the sample from the East China Sea and Prorocentrum dentatum strain (CCMP1517) from the Provasoli-Guillard National Center for Culture of Marine Phytoplankton, USA. The results showed that these two samples belonged to one species. After reviewing literatures,it can concluded that the bloom causative species of the East China Sea is Prorocentrum dentatum, rather than a new species.

Microzooplankton herbivory during red tide-frequent-occurrence period in Spring in the East China Sea

SUN Jun, LIU Dongyan, WANG Zonglin, SHI Xiaoyong, LI Ruixiang, ZHU Mingyuan

2003, (7):  1073-1080. 

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Five typical stations in the Changjiang River estuary and adjacent waters of the East China Sea, were chosen as the sites to study phytoplankton growth and microzooplankton ingestion by on-deck-incubation dilution experiment from 25^th April to 25^th May 2002. The results showed that microzooplankton ingestion was a key process for controlling red tide event.Strombidium sulcatum,Noctiluca scintillans and Mesodinium robudium were dominant microzooplankton species. In this study, the ingestion rate of microzooplankton ranged from 0.28 to 1.13 d^-1; ingestion pressure on percentage of phytoplankton standing crop ranged from 35.14% to 811.69 %; ingestion pressure on percentage of potential production ranged from 74.04% to 203.25 %; and ingestion rate of phytoplankton carbon ranged from 9.58 to 97.91 C稬^-1穌^-1. The microzooplankton grazing rate, ingestion pressure on percentage of phytoplankton standing crop, and ingestion rate of phytoplankton carbon were higher near coastal area, but lower at open sea, and the microzooplankton ingestion pressure on percentage of phytoplankton potential production was on the contrary. Compared with the similar studies around the world, the ingestion pressure of microzooplankton in the East China Sea was at a higher level.The primary deduction was that Strombidium was the key microzooplankton species on controlling Prorocentrum dentatum,the most important red tide species in the East China Sea.

Ecological characteristics of zooplankton in frequent HAB areas of the East China Sea in Spring

XU Zhaoli, HONG Bo, ZHU Mingyuan, CHEN Yaqu

2003, (7):  1081-1085. 

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Acomprehensive oceanographic survey was made in the East China Sea (122°～123°30′E,29°～32°N) during April to May, 2002, and the zooplankton samples were collected by zooplankton net (mesh size 0.567mm).Analyses on the ecological characteristics of zooplankton such as its quantity, community characteristics, species composition and dominant species showed that 128 species of diet zooplankton were identified (16 pelagic larvae and fish juveniles were not involved). Among them, copepods occupied dominant position, including40 species, composing31.25% of diet zooplankton. The community was divided into 3 ecological types, in which,eurythermy and euryhalinity occupied dominant position. Key species,Calanus sinicus, was the first dominant species (142.10 ind·m^-3, composing68.09% of diet zooplankton abundance). The average biomass of zooplankton was 243.80 mg·m^-3 (55.53～773.92mg·m^-3),and the highest density (>500 mg·m^-3) was found in the estuary area of the Yangtze River (30°45′～31°15′N, 122°45′～123°15′E). The average biomass of diet zooplankton was 195.96 mg·m^-3 (55.53～496.09 mg·m^-3). It was also showed that the biomass value of the estuary area of the Yangtze River (the north of 30°30′N ) was higher than that of the southwest of Zhoushan waters,and that of the offshore of the estuary area of the Yangtze River (122°45′E) was higher than that of coastal waters.The mean value of diversity index (H′) was 2.12 (1.09～3.73), and the stations having low H′(<2) occupied 37.03%.The index of diversity, evenness and richness in the estuary area of the Yangtze River were low, but dominance was high. These results showed that the community structure of zooplankton in studied areas was not stable. Regression analysis results showed that main factors in relation to the characteristic distribution of zooplankton were temperature, diatom abundance, and dinoflagellate abundance.

Nutrient distribution and its controlling mechanism in the adjacent area of Changjiang River estuary

SHI Xiaoyong, WANG Xiulin, HAN Xiurong, ZHU Chenjian, SUN Xia, ZHANG Chuansong

2003, (7):  1086-1092. 

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In this paper,the nutrient distribution, its structural characteristic and controlling mechanism around the Changjiang River estuary during Autumn 1997 and Spring 1998 were discussed, and a clear seasonal variation of nutrient distribution and structure was observed in this area. The concentrations of NO₃^--N, SiO₃^2--Si, PO₄^3--P, DOP, PP and TP in Autumn 1997 were higher than those in Spring 1998, and their average concentrations were 4.97, 11.6, 0.44, 0.26, 0.82 and 1.52 μmol·L^-1, respectively. However, the concentrations of NO₂^--N, NH₄⁺-N, DON, PN and TN in Spring1998 were higher than those in Autumn 1997, with the average concentration of 0.70, 2.26, 9.88, 7.88 and 25.3 μmol·L^-1, respectively. The main form of phosphorus in Autumn 1997 was PP, with the percentage about 54%, while PO₄^3--P was the dominant fraction,with about 51% of phosphorus in Spring 1998. Both DON and PN were the main fractions of nitrogen in Autumn 1997 and Spring 1998 as well. Due to the influences of the Changjiang dilution water, the concentrations of phosphate, nitrate and silicate along the coastal area were higher than those in the outer area, except the phosphate in Spring 1998, which mainly came from Taiwan warm current. It indicated that the distribution of the nutrients in the survey area was mainly controlled by the Changjiang dilution water and the high salinity seawater from the Taiwan warm current, and the influence of Taiwan warm current on phosphate was larger in Spring than in Autumn.

Distributions of COD and petroleum hydrocarbons and their relationships with occurrence of red tide in East China Sea

ZHANG Chuansong, WANG Xiulin, SHI Xiaoyong, HAN Xiurong, SUN Xia, ZHU Chenjian, LU Rong

2003, (7):  1093-1096. 

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Based on the data of CODand petroleum hydrocarbons collected in the cruise from April 25 to May 2, 2002 in intensive red tide occurrence areas in East China Sea, the distribution of COD,and petroleum hydrocarbons and the eutrophication index(EI) were analyzed. The results showed that the EI and COD value were both high in coastal water, and decreased gradually away from shore. After the preliminary study on the relationships between correlative factors and occurrence of red tide, it was found that high EIand CODwere necessary. There would be great chances for the red tide to break out under conditions that the EIwas between2.5 and 15 and CODconcentration was between 0.8 to 1.4 mg稬^-1 in seawater, along with the favorable temperature and salinity.

Nutrient distribution and its relationship with occurrence of red tide in coastal area of East China Sea

HAN Xiurong, WANG Xiulin, SUN Xia, SHI Xiaoyong, ZHU Chenjian, ZHANG Chuansong, LU Rong

2003, (7):  1097-1101. 

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Nutrient (NO₃^--N, PO₄^3--P, SiO₃^2--Si, NH₄⁺-N,etc.) concentrations in coastal area of East China Sea were measured during April 25 to May 2, 2002,and the relationship between the spatial distribution of the nutrients and the red tide occurrence in the studied area was analyzed. The results showed that compared to the 1^st class seawater quality of the national standard, the concentrations of dissolved inorganic nitrogen (DIN) and PO₄^--P were 46% and 60% higher, respectively, showing that the studied area, especially the Changjiang River estuary and the Hangzhou Bay, was at a disadvantage of eutrophication. Furthermore, the nutrient concentrations inshore were much higher than those offshore,and the isolines nearly paralleled with the coastline, meaning that the nutrient distributions were mainly influenced by terrestrial discharges. It also showed that the relatively high concentrations of nutrients, especially DIN and PO₄^3--P, might result in the red-tide occurrence. However, the red tide did not occur in the area with the highest concentrations of the nutrients, further demonstrating that the eutrophication was not the unique environmental factor inducing red-tide occurrence.

Sediment chlorophyll in HAB(Harmful Algal Bloom) area of East China Sea

LI Xiaona, ZHOU Weihua, LIU Sumei, ZHANG Jing

2003, (7):  1102-1106. 

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The content and distribution of chlorophyll a (chl-a) and phaeopigments (pha-a) in the sediment of East China Sea was investigated in August and September ,2002.The results showed that chlorophyll a and phaeopigments had the same resource.Both chlorophyll a and phaeopigments decreased significantly with increasing depth, and would be stable to a certain depth.There are several observed leaps in the vertical distribution of chlorophyll a and phaeopigments,which might reflect the effects of bioturbation.The chlorophyll a and phaeopigments concentration on the surface of sediment varied from 0.14 to 1.17 μg·g^-1 and 0.83 to 5.58 μg·g^-1, respectively,and the mean concentrations in the top centimeter of sediment (0～0.5cm) were 0.54μg·g^-1 for chlorophyll a and 2.45μg·g^-1 for phaeopigments.The spatial distribution of benthic chlorophyll a and phaeopigments were affected by the combination of several factors such as depth (and therefore light) ,temperature, salinity and water content.As the main degradation product of chlorophyll a, phaeopigments became the main type of chlorophyll while increased to certain extent,and acounting for 80～90% of total chlorophyll.Due to the water temperature ,the surface chlorophyll a and phaeopigments concentration varied significantly with the season.Total chlorophyll a in the sediment accounted for 31% of total chlorophyll a in the water column.

Nutrient elements in the atmospheric wet deposition in Changjiang River estuary

ZHANG Guosen, CHEN Hongtao, ZHANG Jing, LIU Sumei

2003, (7):  1107-1111. 

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In order to study the effects of atmospheric wet deposition on red tide,five kinds of nutrient elements were measured with 64 rainwater samples collected at Shengsi Archipelago from May 2000 to April 2001. The results showed that there were obvious differences between monthly average concentrations,due to the different resource and precipitation.The variation of seasonal fluxes suggested that the wet deposition might cause red tide except in winter. The annual concentrations of NO₃^--N, NH₄⁺-N, NO₂^--N, PO₄^3--P and SiO₃^2--Si were 20.23, 30.14, 0.11, 0.045 and 3.43μmol·L^-1,respectively,and their annual fluxes were 2.67×10⁸, 3.98×10⁸, 0.014×10⁸, 0.0059×10⁸ and 0.45×10⁸ mol, respectively. Compared with river input,they were much more smaller.

Nutrients regeneration speed of sediment in harmful algae blooms(HAB) area of East China Sea

QI Xiaohong, LIU Sumei, ZHANG Jing, CHEN Hongtao

2003, (7):  1112-1116. 

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The fluxes of dissolved nutrients at sediment-water interface were investigated at 4 stations in the HAB area of East China Sea in May 2001 and May 2002. The benthic fluxes of nutrients were determined by incubating the sediment core samples with bottom seawater bubbled with air or nitrogen. The transfer of nutrients was more active under anoxic condition. The fluxes of dissolved nutrients were generally high at the stations close to the coast. The sediment was the source of SiO₃^2-, which accounted for 6% of primary production. For DIN and PO₄^3-, the sediment was the sink. DIN and PO₄^3- adsorbed by sediment accounted for 5.9% and 67% of the riverine DIN and PO₄^3- inputs, respectively, and the inputs of SiO₃^2- accounted for 7.8%.

Effects of terrestrial input on the harmful algal bloom area-with aluminum as an example

REN Jingling, LIU Sumei, ZHANG Jing, XIE Liang, LI Dandan, CHENG Yan, ZHU Dedi

2003, (7):  1117-1121. 

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In recent years,eutrophication and frequently occurred harmful algal blooms (HAB) become serious in the coastal area near Changjiang River estuary,and the nutrients came from Changjiang River may be the main sources for them. Aluminum could be used as a useful tracer for the terrestrial input and the movement of different water mass, since it enters into the natural water with the erosion products of soil and rock,and its residence time in the ocean is short and uneasy to be disturbed by the activities of human being. Based on our results,the concentration of dissolved Al was higher in Autumn than in Summer,and showed some relationships with the salinity and suspended particulate matter (SPM). The concentration of Al in the HABarea was higher than0.04 μmol·L^-1, which showed the significant influence from the terrestrial input. The concentration of dissolved Al decreased nearly 40% after the occurrence of HAB, and the flocculation of dissolved Al and its absorption onto the surfaces of biogenic particles might be the main reasons. There still need further study about the variation of Al forms and its mechanism during the occurrence of HAB.

Nutrient distributions and their limitation on phytoplankton in the Yellow Sea and the East China Sea

WANG Baodong

2003, (7):  1122-1126. 

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Based on field observations during1997 to 1999,the distributions of micronutrients and their limitation on the growth of phytoplankton in the Yellow Sea and the East China Sea were discussed in this paper. The results showed that there were abundant nutrients in the area of the east and northern-east of the Changjiang River estuary, and the nutrients came from the extension of the Changjiang River diluted water and the transportation of the Subei Coastal water. Besides, the maximum extension range of the nutrients in the Changjiang River diluted water was observed during the catastrophic flooding period of the Changjiang River in the summer of 1998. Based on the Redfield ratio (Si:N:P=16:16:1) in which,three essential nutrients were utilized by marine phytoplankton, the Si/N/P ratios were calculated and studied for the upper water of the Yellow Sea and the East China Sea. The results indicated that Si/N ratios were very high, which suggested that silicate was not the limiting factor for the growth of phytoplankton in the Yellow Sea and the East China Sea. However, under the influence of terrestrial runoff, especially the Changjiang River runoff which was rich in combined nitrogen and had very high N/P ratios, high N/P ratios occured in the Changjiang River estuary and its adjacent areas such as the south and southwest of the Yellow Sea, the inshore area of the East China Sea and the area east of the Changjiang River estuary in spring and summer. As a result, in contrast to general open marine systems, the systems in these areas resembled estuarine ones rather than typical marine ones. The primary production in a considerable portion of the Yellow Sea and the East China Sea might be limited by phosphate rather than nitrogen.

Temporal dynamics of phytoplankton and nutrients during red tides

QIU Yaowen, ZHU Liangsheng, LI Jinrong, LIANG Song, QI Yuzao

2003, (7):  1127-1130. 

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The relationships between temporal dynamics of phytoplankton density and nutrients (NO₃^-,NH₄⁺,PO₄^3-,SiO₃^2-,Fe) contents in the water body at Aotou waters of Daya Bay during red tide were comprehensively analysed based on the fixed position investigation of red tide in the summer of 2000 and the several years investigation data by using grey linear regression model. The relationships between phytoplankton cell density and chlorophyll a content were also analysed. The results showed that the predicted values were well consistent with the measurement values, and their correlation coefficients were between 0.51～0.83. Red tide might break out if chlorophyll a contents in water body were larger than 5.8 μg·dm^-3. The study could provide a simple effective method to forecast red tide by sampling water samples to analyse chlorophyll a concentration,or using Sea WiFS data,and then,to calculating phytoplankton density. In addition, the primary productivity of the water areas was controlled by phosphorus.

Hydrologic distribution characteristics of HAB frequent occurrence area in the outer Changjiant River estuary

ZHU Dedi, PAN Yuqiu, XU Weiyi, CHEN Qiaoyun

2003, (7):  1131-1134. 

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Based on survey data, this paper analysed the hydrologic characteristics of HABfrequent occurrence area in the outer Changjiang River estuary.The results showed that this area is an area in which the plume front with a salinity of 17～30 in the outer Changjang River estuary,the divergent surface current of the plume front and the upwelling of the high salinity Taiwan bottom warm current are coexisted.In Spring and Summer, the diluted Changjiang River water of this area changed its flow direction under the effect of southwest-northeastward current,possibly due to the large runoff from the Changjiang River to the sea.The upwelling usually occurred at the west side slope between the first turning point and the deep slot top of the outer Changjiang River esturary. This turning point was on the north side in Spring and on the south side in Summer, but in Autumn, no turning point was existed, possibly due to the small runoff. The distribution characteristics of residual current in Spring and Summer was that the adjacent area of plume front was the convergent area of surface and bottom currents,the surface residual current in the upwelling area was at divergent,and the bottom residual current had the characteristics of converging toward the Changjiang River estuary along the deep slot.

Distribution of phytoplankton and water dynamical environmental factors in high red tide occurrence area of Changjiang River estuary

ZHU Genhai, XU Weiyi, ZHU Dedi, SHI Qingsong, ZHANG Jian

2003, (7):  1135-1139. 

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Species composition and cell abundance of phytoplankton, and its relations with environmental factors were investigated in the Changjiang River estuary of east China sea (30°50′～31°50′ N,121°50′～123°00′E). Atotal of 110 taxa belonging to 45 genera of phytoplankton in the investigation area were identified. The main species of phytoplankton resulted in red tide were Skeletonema costatum and Prorocentrum dentatum, etc. Phytoplankton abundance in the day was higher than that at night. The vertical distribution of phytoplankton in different water bodies was not obvious. The ecological groups of phytoplankton were freshwater group, estuarine and brackish water and low salinity group in the coast, high salinity and warm water group in off-sea, and widely ranging group. The abundance of phytoplankton in the Changjiang River estuary was 1.6×10³～75.2×10³ind·dm^-3. The species composition and cell abundance of phytoplankton were related to the freshwater pouring into the Changjiang River estuary. The three waters in the area affecting the distribution of phytoplankton were the Changjiang River estuary water, freshwater, and warm water from outsea.

Response of Prorocentrum minimum growth to zinc limitation

HU Hanhua, SHI Yanjun, CONG Wei, CAI Zhaoling, OUYANG Fan

2003, (7):  1140-1142. 

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Studies on the growth and physiological response of red tide alga Prorocentrum minimum to three Zn ²⁺ levels were showed that the specific growth rate and biomass were limited in low Zn ²⁺-grown cells (1.4 pmol·L^-1, which were 0.40 d^-1 and 51100 cell·ml^-1 respectively. The specific growth rate was not significantly different when the Zn ²⁺ concentration in medium was increased over 24.4 pmol·L^-1,but there was a slight decrease in biomass; however, both specific growth rate and biomass were much higher than those in low Zn ²⁺-grown cells. It was also showed that chlorophyll a synthesis was limited due to Zn ²⁺ deficient,and therefore,the cells became light saturated at higher irradiance under Zn-limited condition. Light-saturated photosynthetic rates (Pm) and photosynthetic efficiency (α) increased significantly with increasing Zn ²⁺ concentrations. It was concluded that Zn ²⁺ concentration might be one of the key factors affecting red tide blooms in eutrophication environment.

Nitrogen and phosphorus absorption and growth characteristics of Alexandrium tamarense

SHI Yanjun, HU Hanhua, MA Runyu, CONG Wei, CAI Zhaoling

2003, (7):  1143-1146. 

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The uptake of nitrate and phosphate by Alexandrium tamarense and its growth characteristics were studied in laboratory cultures, which were conducted using environmentally realistic levels of physical factors during red tide occurrences. The results indicated that the specific growth rate had little difference under three nitrate levels (low-nitrate, 0.0882 mmol稬^-1; middle-nitrate, 0.882 mmol稬^-1; high-nitrate, 2.646 mmol稬^-1).The cell yield was the lowest at low-nitrate, a maximum yield was achieved at the middle-nitrate, which increased by 44.7% and 53.6% respectively,compared with high-nitrate and low-nitrate. The cell yield increased with increasing phosphate concentrations in cultures (low-phosphate, 0.0036 mmol稬^-1; middle-phosphate, 0.036 mmol稬^-1; high-phosphate, 0.108 mmol稬^-1), and the maximum yield (17200 cell穖l^-1) was observed at high-phosphate concentration, while the maximum specific growth rate occurred at middle-phosphate. The growth conditions had a significant effect on the uptake rate of nitrate and phosphate by cells, and the cells grown in low-nitrate and low-phosphate cultures had a higher uptake rate. Further experiment suggested that lower ratio of N/Ppromoted the propagation of cells, and the supplementation of nitrate at later exponential growth phase had a positive effect to the accumulation of biomass.

Distribution and germination of Alexandrium sp.cysts in coastal areas of Southeast China Sea

GU Haifeng, LAN Dongzhao, FANG Qi, WANG Zonglin, CAI Feng

2003, (7):  1147-1150. 

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Studies on the distribution and germination of Alexandrium sp.(A. tamarense+A. catenella) cysts in coastal areas of Southeast China showed that the cysts were only found at X1 and X2 of Xiamen Harbor, whose density was quite low (0.4 ind·g^-1). In Guangxi,the cysts were found at G2 station, with a density of 2.5 ind·g^-1. There were cysts at three stations at Minjiang River estuary. The density reaches maximum value at 4～6cm sediment of M4 station, up to 6 ind·g^-1.In Changjiang River estuary,the cysts distributed widely and had the largest density, up to 23.2 ind·g^-1 at 8～10cm sediment of DG-26 station. The distribution of Alexandrium sp.cysts was relevant to sediment type, sedimentation rate and current. Light had no effect on germination. With increasing temperature, germination and survival rates also increased, while the germination time decreased. Anoxia (0.01mg O₂·L^-1 ) inhibited germination completely.Alexandrium sp. cysts could germinate throughout the year under favorable conditions.

Effects of Alexandrium tamarense and Prorocentrum donghaiense on rotifer Brachionus plicatilis population

WANG Liping, YAN Tian, TAN Zhijun, ZHOU Mingjiang

2003, (7):  1151-1155. 

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The effects of Prorocentrum donghaiense and Alexandrium sp., causative species of harmful algal bloom of East China Sea in May 2002, on rotifer Brachionus plicatilis population were studied in the laboratory. The results showed that Alexandrium tamarense(ATHK) had a lethal effect on B.plicatilis and the 48hLC₅₀ was about 1300 cell穖l^-1. The toxin comparison of different fractions showed that the algal culture and re-suspended algal cells had the adverse effects, and the alga at earlier growth phases showed a stronger impact, indicating that the inhibitory effect was related with the activity of the living algal cells. P.donghaiense at high densities(4?10⁴,5?10⁴ and 10?10⁴ cell穖l^-1) had an adverse effect on B.plicatilis population, while at low densities(1?10⁴,2?10⁴ and 3?10⁴ cell穖l^-1), the alga could be used as food for rotifer population. When the two algae were mixed, the lethal effect of A.tamarense could be decreased by P.donghaiense.The results indicated that the above HAB event could affect the micro-zooplankton population in the occurrence area of East China Sea.

Paralytic shellfish toxins in shellfish from the coast of high frequent harmful algae blooms occurrence areas in East China Sea and South China Sea

JIANG Tianjiu, CHEN Jufeng, ZOU Yinlin, LIU Jiesheng, YANG Weidong

2003, (7):  1156-1160. 

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The paralytic shellfish poisoning (PSP) toxicity levels of shellfish collected from shellfish growing zones in Zhoushan areas of East China Sea and Shenzhen areas of South China Sea during January-November 2002 were determined with AOAC bioassay method. The results showed that the toxicity levels of shellfish from Zhoushan were very low,and few shellfish samples could be detected the PSPtoxicities.The same levels appeared in the shellfish from Shenzhen, but the percentage of shellfish samples contaminated PSP was up to 30%, and the scallop Chalmys nobilis was dominated in the contaminated shellfish species.Analyses on the toxic profiles of digest gland and edible tissue extraction of scallop from Shenzhen showed that a similar suite of toxins presented in the gland and edible tissues.The high potency neo STX and low potency GTX₅ had a high proportions, up to 60.8% and 11.4%,respectively in the tissue, and the high potency GTX ¹⁺² and GTX₅ were the dominant toxins, up to 38.9% and 20%,respectively in the gland. Most of the toxin were accumulated in ingested gland of scallop,and the toxic content in gland was about 8 folds more than that in the edible tissues.

Effects of marine bacteria on the growth and toxin production of red-tide algae under different pH and salinities

SU Jianqiang, ZHENG Tianling, HU Zhong, XU Jingsen, YU Zhiming, SONG Xiuxian

2003, (7):  1161-1164. 

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The effects of strain S₁₀ isolated from sediments of Xiamen Western Sea Area on the growth and paralytic shellfish poison (PSP) production of Alexandrium tamarense at different pHand salinities were studied. The results showed that the alga grew well at pH6～8 and at salinity of 20～34. The toxicity of A. tamarense varied markedly at different pH and salinities:it decreased with increasing pH,while increased with salinity and reached its peak value at the salinity of 30, and then declined. The strain S₁₀ inhibited the growth and the PSP production of A. tamarense at different pH and salinities.It had the best inhibitory function on the growth of A. tamarense at pH7 and salinity of 34. The best inhibitory function on the PSP production of A.tamarense was at pH7, but this inhibitory function was not related to salinity.

Removal of different species of red tide organisms with an effective clay-complex system

SONG Xiuxian, YU Zhiming, GAO Yonghui

2003, (7):  1165-1168. 

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An effective clay-complex system was composed on the base of clay by added other two components Aand B. Different red tide species, such as Scrippsiella trochoidea, Amphidinium carterae and Heterosigma akashiwo, were coagulated by this clay-complex system,and the optimum conditions for removal red tide organisms were obtained by means of orthogonal test. The results showed that clay was the most important factors in this complex system to coagulate these three organisms. The removal efficiency on three species was in order of Scrippsiella trochoidea > Amphidinium carterae > Heterosigma akashiwo. At the same time, a preliminary study of mortality rate on Penaeus japonicus (length between 1.0 to 1.5cm) was conducted with this system,and the result of toxic test revealed that the mortality of aquiculture shrimp in control group (nothing added) reached to 80% after 96h, however,while that of other three groups which added clay and other two components Aand B, was below 40%.Thus,it implied that the addition of clay would be harmless to Penaeus japonicas. Furthermore, suitable concentration of components Aand Bwas not harmful for the aquiculture shrimp, but increased the removal efficiency of red tide organisms. The preliminary results showed that this clay-complex system would be available in the removal of red tide organisms in filed.

Extinguishment of harmful algae by organo-clay

CAO Xihua, YU Zhiming

2003, (7):  1169-1172. 

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Periodic and widespread algal blooms have caused a variety of problems for aquatic life and human activity throughout the world. Currently, the only remedial practice employed for removing algal blooms is to spread clay on the surface of the water.But,the algal removal efficiency by the crude minerals are not really ideal, and how to improve the capability of clays to remove algae is now the technological focus, which also is fatal to the practical value of clays. In this study, hexadecyltrimethyleamine bromide (HDTMAB), one kind of cationic organo-surfactants, was chosen to improve kaolin by surface sorption and cationic exchange, and was tested to remove Prorocentrum donghaiense, a red tide organism in Donghai Sea. The results indicated that organo-clay had an excellent ability to extinguish red tide organisms, even under the application of 0.01g稬^-1, and could subside more than 95% red tide organisms in24h. The efficient algae removal by organo-clay might be from the reversal of the surface electric charge on clay particles, the "net capture" by the long lipoid chains of HDTMAB,and the local high density of HDTMAB on particles surface, which could effectively kill algal cells.

Inhibition and elimination of chlorine dioxide on Phaeocystis globosa

ZHANG Heng, YANG Weidong, GAO Jie, LIU Jiesheng

2003, (7):  1173-1176. 

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Different densities of red tide organism,Phaeocystis globosa(STstrain) were exposed to different concentrations of chlorine dioxide.The results showed that chlorine dioxide could effectively kill and control the algae. When the algae,in the density of 2.35?10⁹ cells稬^-1,was exposured to ClO₂ above 0.74?10^-2 mmol稬^-1,it was inhibited,and eliminated under ClO₂ concentration above 2.96?10^-2 mmol稬^-1. When the density of algae was 2.35?10⁹,1.18?10⁹,4.70?10⁸ and 1.18?10⁸ cells稬^-1,the concentration of chlorine dioxide which could kill the algae efficiently in96 h was 2.96?10^-2,2.22?10^-2,1.48?10^-2 and 0.59?10^-2 mmol稬^-1,respectively. Under the same rate of inhibition or elimination,the higher the density of algae was,the lower the concentration of chlorine dioxide was to effectively control the growth of algae cell,ClO₂ could be considered as a potential algaecide to control red tide.

Povidone-iodine and isothiozolone for removing red tide algae Phaeoecystis globosa

HONG Aihua, YIN Pinghe, ZHAO Ling, HUANG Yunfeng, QI Yuzao, XIE Longchu

2003, (7):  1177-1180. 

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Studies on the removal and control of red tide algae Phaeoecystis globosa by povidone-iodine and isothiozolone algaecide showed that Phaeoecystis globosa could be killed and controlled by povidone-iodine and isothiozolone. The effective concentration of povidone-iodine was 30 mg稬^-1, and that of isothiozolone was 0.30 mg稬^-1. Using povidone-iodine and isothiozolone together could improve the effect, and the ideal composite ratio of povidone-iodine and isothiozolone was 1.0:0.15.

Spectroscopic properties of Heterosigma akashiwo under iron limitation

LI Dongxia, CONG Wei, CAI Zhaoling, SHI Dingji, OUYANG Fan

2003, (7):  1181-1184. 

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Room-temperature absorption spectra of H. akashiwo cells under iron limitation showed a chlorophyll c absorption peak at 630 nm, 2 nm blue-shifted from its normal position of 632 nm. Moreover, because of the increase in the relative carotenoid abundance compared to Chl a, there was an extra shoulder peak at 480 nm for the iron-limited cells. Their fluorescence spectra (77 K) have one prominent chlorophyll emission peak at 685 nm. By comparison with Fe-replete cells (10 μmol·L^-1), the fluorescence yield from 685 nm band increased by about 2 times in Fe deplete cells (5 nmol·L^-1),and about 1.4 times in low iron cells (100 nmol·L^-1),respectively. 48 h after Fe addition, the height of 685 nm peak was considerably decreased from that observed in low iron (100 nmol·L^-1) and iron deficient (ID) cells before Fe addition,which indicated that there was a significantly higher energy dissipation, and thus,a less effective photosynthesis under the lack of Fe.

Induction of biochemical composition in Heterosigma akashiwo under Fe stress

LI Dongxia, CONG Wei, CAI Zhaoling, SHI Dingji, OUYANG Fan

2003, (7):  1185-1187. 

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The iron-stress mediated effects on biochemical constituents of red tide alga H. akashiwo were examined in Fe-replete and iron deficiency,and low iron batch cultures. The content of all pigments decreased under iron limitation,and the cellular chlorophyll a concentration decreased by more than 2-fold compared to that under iron replete condition. This change in Chl a was accompanied by a corresponding decrease in Chl c per cell, resulting in no trend in the ratio of Chl c to Chl a. The cellular carotenoids content decreased by more than1.5-fold compared to that under iron replete condition. As a consequence, carotenoids/chlorophyll a ratio increased in Fe-deficient cells. Carbohydrate content was reduced under iron stress,and total proteins decreased with the decrease of iron concentration. Acrude fractionation of the soluble proteins demonstrated that 17 kDand 55 kDa proteins in soluble fraction were induced.

What the Prorocentrum species should be? -A review on identification of a Prorocentrum species from the East China Sea

QI Yuzao, WANG Yan

2003, (7):  1188-1190. 

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In the past decade, the Prorocentrum bloom was the most frequently occurred bloom in the East China Sea. It occurred every one year or two years, and covered huge areas. There were arguments on the identification of Prorocentrum bloom causative species. Some scientists thought the species being P. dentatum Stein, but the others thought that it was a new species, P. donghaiense Lu. For achieving the proper classification of the species, an "International Workshop on HAB Causative Species-Taxonomic View on a species of Prorocentrum in the East China Sea" was held in Shenzhen, China in November, 2002. By reviewing as much as available references, and by comparing the Prorocentrum specimen from the East China Sea with those from Japan, Korea and USA, scientists participated in this Workshop agreed that: 1) the specimens from Japanese and Korean waters, and from CCMP, USA were the same species; 2) the features of anterior projection and cell surface marking were similar to those of originally described P. dentatum Stein; 3) the major difference is the cell size. The specimens from the East China Sea were mostly less than20 μm long, whereas the size of the original described P. deatatum was larger than 50 μm; 4) the minor difference is the shape of the cell end. The original described P. deatatum was with a pointed end, whereas the cells from the East China Sea were mostly with a rounded end. There was no final agreement for the species identification at the Workshop. By summing all views of scientists from the Workshop, the authors suggested that the bloom causative species of Prorocentrum in the East China Sea, as well as so-called species of P. dentatum from other East Asian waters, should be the same species. They are all P. donghaiense Lu.

Research advance in effects of harmful algal bloom species on zooplankton

WANG Liping, YAN Tian, TAN Zhijun, ZHOU Mingjiang

2003, (7):  1191-1196. 

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The research on the effects of harmful algal bloom (HAB) algae on zooplankton has been drawn more and more attention. This paper summarized the adverse effects of HABalgae on zooplankton,which included reduced survival,inhibited growth,reduced fecundity of female, fertilization failure of eggs or hatching failure of zygote,inhibited embryo development,naupliar abnormal development or abnormality,inhibited grazing and changed behavior of zooplankton, etc. The main intoxication ways included decreased utilization of food,physiology impairment,damaged cell membrane,reduced gamete quality,and inhibited mitotic and embryo development by phycotoxins or exudations released by algae. Additionally, the lack of full nutrition,especially of polyunsaturated fatty acids in some algal species cells could also affect zooplankton growth and reproduction.

Advances in researches of aquatic ectoenzyme and its relationship with red tide

OU Linjian, HUANG Bangqin, HONG Huasheng, WANG Dazhi

2003, (7):  1197-1199. 

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Ectoenzymes play an important role in the material cycle and energy conversion in aquatic ecosystem. The researches of ectoenzyme are of significance in further understanding the marine carbon biogeochemical cycle and the countermeasures of algae under bloom conditions.In this paper, the research methods, characteristic activity and size distribution, controlling factors and their ecological significances of algal ectoenzymes were reviewed, and ectoenzyme introduced as one kind of new trophic state index.

Algorithms of multiband remote sensing for coastal red tide waters

MAO Xianmou, HUANG Weigen

2003, (7):  1200-1202. 

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The spectral characteristics of the coastal waters in East China Sea was studied using in situ measurements,and the multiband algorithms of remote sensing for bloom waters was discussed and developed. Examples of red tide detection using the algorithms in the East China Sea were presented. The results showed that the algorithms could provide information about the location and the area coverage of the red tide events.

Spectrophotometer detection of benzalkonium bromide concentration in seawater

PAN Jianyu, YIN Pinghe, ZHAO Ling, QI Yuzao, XIE Longchu

2003, (7):  1203-1204. 

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Benzalkonium bromide is a high-efficiency algaecide.Its concentration in seawater was measured by the method of spectrophotometer. The results indicated that the deposition appeared if the concentration of benzalkonium bromide in seawater was more than 50mg稬^-1,and affected the detection of benzalkonium bromide.But,there was a good linear relationship between concentration and absorbance when the concentration was lower than 50mg稬^-1 (R²=0.9996). Therefore,spectrophotometer could be used to detect benzalkonium bromide in seawater.

Preliminary analysis of the characteristics of red tide areas in Changjiang River estuary and its adjacent sea

ZHOU Mingjiang, YAN Tian, ZOU Jingzhong

2003, (7):  1031-1038. 

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A review was made on the main environmental characteristics such as currents and water body,diluted water and its turning direction,upwelling,front,nutrients and its sources and plankton community in the Changjiang River estuary and its adjacent sea areas which could affect the growth,migration,assembling,resting and competition of harmful algae to form red tides. Analyses were also conducted to reveal features of the red tides events recorded in this area in terms of time,location and causative species. Some preliminary results from recent cruises carried out in the investigated sea area,where red tides were frequently occurring,were introduced.

Distribution of dinoflagellate resting cysts in surface sediments from the Changjiang River estuary

WANG Zhaohui, Qi Yuzao

2003, (7):  1039-1043. 

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In order to understand the potential of algal blooms, surface sediments were collected from 12 stations in the Changjiang River estuary with longitude from 122? to 123.5癊and latitude from 29? to 32癗from April to May 2002 to investigate the distribution of dinoflagellate resting cysts. 29 different cyst morphotypes representing19 genera and 6 groups were identified.Among them, there were 11 autotrophic species and 18 heterotrophic ones. The number of species observed in each sample was low, and varied from 10 to 21. Cyst concentrations varied from 11.7 to 587 cysts per gram dry weight. Cyst concentrations and species diversity were higher in offshore areas,and increased from the west to the east, and from the north to the south within the studied area. Cysts of Alexandrium distributed widely in the Changjiang River estuary,with the maximum concentration of 40.4 cysts per gram dry weight. Cysts of harmful algal bloom causative species such as Alexandrium, Gymnodinium catenatum, Lingulodinium polyedra, Scrippsiellla trochoidea, Polykrikos kofoidii and P. schwartzii were also observed in this survey.

Species composition and ecological distribution of planktonic diatoms in the Changjiang River estuary during Spring

GAO Yahui, YU Qiubo, QI Yuzao, ZHOU Jingzhong, LU Douding, LI Yang, CHENG Changping

2003, (7):  1044-1048. 

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water samples were collected from 28 stations in typical regions where redtide frequently occurred in the Changjiang River estuary during Spring, 2002. In total, 80 diatom species and varieties belonging to 31 genera were identified, among which, genera with high species biodiversity included Coscinodiscus which contained 17 species and Pleurosigma which contained 8 species and varieties. Quantitative analysis of diatom cell density showed that Pseudo-nitzschia delicatissma (3.48×10³cells·L^-1, 28.54%),Melosira sulcata(1.43×10³cells·L^-1, 16.98%)and Pseudo-nitzschia pungens(0.71×10³cells·L^-1, 9.85%) were dominant species, which occurred at almost all stations. Higher cell density of Pseudo-nitzschia delicatissma and Pseudo-nitzschia pungens occurred at stations along123°E, while that of Melosira sulcata occurred at stations around Changjiang River at 31～32°N. The total diatom cell density ranged from 0.43×10³～23.3×10³cells·L^-1,with average of 4.61×10³cells·L^-1. At station DD15 located at 123°E and 30.5°N, the highest diatom cell density was found,which was 1.85×10⁴cells·L^-1 at surface water layer, and 2.33×10⁴cells·L^-1 at middle water layer (30m) respectively. Horizontally, the diatom cell density showed scattered distribution, while vertically,it was commonly higher at surface water layer than that at middle water layer.

Mesocosm experiment on competition between two HAB species in East China Sea

LI Ruixiang, ZHU Mingyuan, WANG Zongling, SHI Xiaoyong, CHEN Bingzhang

2003, (7):  1049-1054. 

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Skeletonema costatum and Prorocentrum dentatum are the two common HAB species in East China Sea, and Prorocentrum is more responsible for most HAB events in Spring since late 90's. The HAB caused by Skeletonema usually occurs from June to August. However, these two species will not bloom at the same time. Two mesocosm experiments were conducted in East China Sea in May 1998 and May 2002. In the experiment of May 1998, the cell number of Prorocentrum dentatum and Skeletonema costatum accounted for about 85% and 11% of total cell number of phytoplankton,respectively at the beginning of the experiment. In control mesocosm, Prorocentrum dentatum dominated the community during the whole experiment. In phosphate-enriched mesocosm, however, Skeletonema costatum showed a high competition capability. In May 2002, there were 4 bags in the mesocosm experiment. At the beginning of the experiment, the cell number of Prorocentrum dentatum accounted for 55～66 % of the total,and that of Skeletonema costatum accounted for 32～42 %. During the experiment, the growth of Skeletonema costatum was faster than that of Prorocentrum dentatum.On the 2nd day, the cell number of Skeletonema costatum exceeded that of Prorocentrum dentatum. It showed that under high nutrients conditions,Skeletonema costatum grew better than Prorocentrum dentatum,but under nutrients-limited conditions,Prorocentrum dentatum could survival better than Skeletonema costatum.

Distribution features of chlorophyll a and primary productivity in high frequency area of red tide in East China Sea during Spring

ZHOU Weihua, HUO Wenyi, YUAN Xiangcheng, YIN Kedong

2003, (7):  1055-1059. 

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The distributions of chlorophyll a and primary productivity were determined during April to May 2002 in the East China Sea. The results showed that the average concentration of chlorophyll a was 1.086 mg·m^-3 at surface layer,and that nano-and pico-phytoplankton (<20μm) dominated the phytoplankton biomass in this sea region during Spring (up to 64% of total chlorophyll a content). Ultra-phytoplankton (<5μm) consisted 27% of total phytoplankton biomass. Nutrients and feeding pressure of zooplankton affected the distribution of chlorophyll a and its size-fractionation. The average primary productivity was 10.091 mg·m^-3·h^-1,while that of red tide tracking stations R-03, RL-01 and RG-01 was 399.984 mg·m^-3·h^-1. Light and nutrients were the main factors affecting the distributions of chlorophyll a and primary productivity. The station DC-11 had a high concentration of phytoplankton biomass.The surface layer concentration of chlorophyll a and primary productivity were up to 9.082 mg·m^-3 and 128.79 mg·m^-3·h^-1, respectively,but the color of the seawater was normal.

Redescription of Prorocentrum donghaiense Lu and comparison with relevant Prorocentrum species

LU Douding, QI Yuzao, Jeanette Goebel, ZOU Jingzhong, GAO Yahui

2003, (7):  1060-1064. 

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In this paper,the detailed morphology of Prorocentrum donghaiense was studied.Taxonomic comparison was made between P.donghaiense and other relevant Prorocentrum species. The results suggested that distinct differences existed among them with respect to their conservative characteristics of morphology and cell sizes. This kind of discrepancy was far beyond that of individual variations within same species due to environmental factors. Therefore, the high biomass bloom-forming species in the East China Sea was not real Prorocentrum "dentatum" Stein, but P. donghaiense Lu that was re-described in the present paper.P. donghaiense appeared in the East China Sea,and P."dentatum" occurred in Japanese and Korean waters should be the same species.

Ecological characteristics of Prorocentrum dentatum and the cause of harmful algal bloom formation in China Sea

WANG Jinhui, HUANG Xiuqing

2003, (7):  1065-1069. 

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Large-scale harmful alga bloom (HAB) has been found in Changjiang River estuary and Zhoushan archipelago in recent three years, and the alga is Prorocentrum dentatum, which distributes in the sea areas with high salinity and (may) originates in outer sea area. Data from recent HAB rapid monitoring and ecological investigation were analyzed to study its ecological characteristics and forming inducement. The results showed that the most suitable temperature and salinity range for HAB forming was from 18℃ to 22℃ and from 21 to 31, respectively. The P. dentatum was motile and owned diurnal vertical migration bringing them the advantages in obtaining light and nutrients.Eutrophication was the preliminary condition, and water temperature,nitrate content, upwelling current,and strong competence on low phosphate environment were important to cause and maintain HAB.

Scanning electron-microscopic study on Prorocentrum dentatum from the East China Sea

LU Songhui, ZHANG Yuyu, CHEN Jufang

2003, (7):  1070-1072. 

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There is an argument whether the bloom causative species of the East China Sea is Prorocentrum dentatum or a new species. Based on the scanning electron-microscopic study, we compared the detailed surface structure of the sample from the East China Sea and Prorocentrum dentatum strain (CCMP1517) from the Provasoli-Guillard National Center for Culture of Marine Phytoplankton, USA. The results showed that these two samples belonged to one species. After reviewing literatures,it can concluded that the bloom causative species of the East China Sea is Prorocentrum dentatum, rather than a new species.

Microzooplankton herbivory during red tide-frequent-occurrence period in Spring in the East China Sea

SUN Jun, LIU Dongyan, WANG Zonglin, SHI Xiaoyong, LI Ruixiang, ZHU Mingyuan

2003, (7):  1073-1080. 

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Five typical stations in the Changjiang River estuary and adjacent waters of the East China Sea, were chosen as the sites to study phytoplankton growth and microzooplankton ingestion by on-deck-incubation dilution experiment from 25^th April to 25^th May 2002. The results showed that microzooplankton ingestion was a key process for controlling red tide event.Strombidium sulcatum,Noctiluca scintillans and Mesodinium robudium were dominant microzooplankton species. In this study, the ingestion rate of microzooplankton ranged from 0.28 to 1.13 d^-1; ingestion pressure on percentage of phytoplankton standing crop ranged from 35.14% to 811.69 %; ingestion pressure on percentage of potential production ranged from 74.04% to 203.25 %; and ingestion rate of phytoplankton carbon ranged from 9.58 to 97.91 C稬^-1穌^-1. The microzooplankton grazing rate, ingestion pressure on percentage of phytoplankton standing crop, and ingestion rate of phytoplankton carbon were higher near coastal area, but lower at open sea, and the microzooplankton ingestion pressure on percentage of phytoplankton potential production was on the contrary. Compared with the similar studies around the world, the ingestion pressure of microzooplankton in the East China Sea was at a higher level.The primary deduction was that Strombidium was the key microzooplankton species on controlling Prorocentrum dentatum,the most important red tide species in the East China Sea.

Ecological characteristics of zooplankton in frequent HAB areas of the East China Sea in Spring

XU Zhaoli, HONG Bo, ZHU Mingyuan, CHEN Yaqu

2003, (7):  1081-1085. 

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Acomprehensive oceanographic survey was made in the East China Sea (122°～123°30′E,29°～32°N) during April to May, 2002, and the zooplankton samples were collected by zooplankton net (mesh size 0.567mm).Analyses on the ecological characteristics of zooplankton such as its quantity, community characteristics, species composition and dominant species showed that 128 species of diet zooplankton were identified (16 pelagic larvae and fish juveniles were not involved). Among them, copepods occupied dominant position, including40 species, composing31.25% of diet zooplankton. The community was divided into 3 ecological types, in which,eurythermy and euryhalinity occupied dominant position. Key species,Calanus sinicus, was the first dominant species (142.10 ind·m^-3, composing68.09% of diet zooplankton abundance). The average biomass of zooplankton was 243.80 mg·m^-3 (55.53～773.92mg·m^-3),and the highest density (>500 mg·m^-3) was found in the estuary area of the Yangtze River (30°45′～31°15′N, 122°45′～123°15′E). The average biomass of diet zooplankton was 195.96 mg·m^-3 (55.53～496.09 mg·m^-3). It was also showed that the biomass value of the estuary area of the Yangtze River (the north of 30°30′N ) was higher than that of the southwest of Zhoushan waters,and that of the offshore of the estuary area of the Yangtze River (122°45′E) was higher than that of coastal waters.The mean value of diversity index (H′) was 2.12 (1.09～3.73), and the stations having low H′(<2) occupied 37.03%.The index of diversity, evenness and richness in the estuary area of the Yangtze River were low, but dominance was high. These results showed that the community structure of zooplankton in studied areas was not stable. Regression analysis results showed that main factors in relation to the characteristic distribution of zooplankton were temperature, diatom abundance, and dinoflagellate abundance.

Nutrient distribution and its controlling mechanism in the adjacent area of Changjiang River estuary

SHI Xiaoyong, WANG Xiulin, HAN Xiurong, ZHU Chenjian, SUN Xia, ZHANG Chuansong

2003, (7):  1086-1092. 

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In this paper,the nutrient distribution, its structural characteristic and controlling mechanism around the Changjiang River estuary during Autumn 1997 and Spring 1998 were discussed, and a clear seasonal variation of nutrient distribution and structure was observed in this area. The concentrations of NO₃^--N, SiO₃^2--Si, PO₄^3--P, DOP, PP and TP in Autumn 1997 were higher than those in Spring 1998, and their average concentrations were 4.97, 11.6, 0.44, 0.26, 0.82 and 1.52 μmol·L^-1, respectively. However, the concentrations of NO₂^--N, NH₄⁺-N, DON, PN and TN in Spring1998 were higher than those in Autumn 1997, with the average concentration of 0.70, 2.26, 9.88, 7.88 and 25.3 μmol·L^-1, respectively. The main form of phosphorus in Autumn 1997 was PP, with the percentage about 54%, while PO₄^3--P was the dominant fraction,with about 51% of phosphorus in Spring 1998. Both DON and PN were the main fractions of nitrogen in Autumn 1997 and Spring 1998 as well. Due to the influences of the Changjiang dilution water, the concentrations of phosphate, nitrate and silicate along the coastal area were higher than those in the outer area, except the phosphate in Spring 1998, which mainly came from Taiwan warm current. It indicated that the distribution of the nutrients in the survey area was mainly controlled by the Changjiang dilution water and the high salinity seawater from the Taiwan warm current, and the influence of Taiwan warm current on phosphate was larger in Spring than in Autumn.

Distributions of COD and petroleum hydrocarbons and their relationships with occurrence of red tide in East China Sea

ZHANG Chuansong, WANG Xiulin, SHI Xiaoyong, HAN Xiurong, SUN Xia, ZHU Chenjian, LU Rong

2003, (7):  1093-1096. 

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Based on the data of CODand petroleum hydrocarbons collected in the cruise from April 25 to May 2, 2002 in intensive red tide occurrence areas in East China Sea, the distribution of COD,and petroleum hydrocarbons and the eutrophication index(EI) were analyzed. The results showed that the EI and COD value were both high in coastal water, and decreased gradually away from shore. After the preliminary study on the relationships between correlative factors and occurrence of red tide, it was found that high EIand CODwere necessary. There would be great chances for the red tide to break out under conditions that the EIwas between2.5 and 15 and CODconcentration was between 0.8 to 1.4 mg稬^-1 in seawater, along with the favorable temperature and salinity.

Nutrient distribution and its relationship with occurrence of red tide in coastal area of East China Sea

HAN Xiurong, WANG Xiulin, SUN Xia, SHI Xiaoyong, ZHU Chenjian, ZHANG Chuansong, LU Rong

2003, (7):  1097-1101. 

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Nutrient (NO₃^--N, PO₄^3--P, SiO₃^2--Si, NH₄⁺-N,etc.) concentrations in coastal area of East China Sea were measured during April 25 to May 2, 2002,and the relationship between the spatial distribution of the nutrients and the red tide occurrence in the studied area was analyzed. The results showed that compared to the 1^st class seawater quality of the national standard, the concentrations of dissolved inorganic nitrogen (DIN) and PO₄^--P were 46% and 60% higher, respectively, showing that the studied area, especially the Changjiang River estuary and the Hangzhou Bay, was at a disadvantage of eutrophication. Furthermore, the nutrient concentrations inshore were much higher than those offshore,and the isolines nearly paralleled with the coastline, meaning that the nutrient distributions were mainly influenced by terrestrial discharges. It also showed that the relatively high concentrations of nutrients, especially DIN and PO₄^3--P, might result in the red-tide occurrence. However, the red tide did not occur in the area with the highest concentrations of the nutrients, further demonstrating that the eutrophication was not the unique environmental factor inducing red-tide occurrence.

Sediment chlorophyll in HAB(Harmful Algal Bloom) area of East China Sea

LI Xiaona, ZHOU Weihua, LIU Sumei, ZHANG Jing

2003, (7):  1102-1106. 

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The content and distribution of chlorophyll a (chl-a) and phaeopigments (pha-a) in the sediment of East China Sea was investigated in August and September ,2002.The results showed that chlorophyll a and phaeopigments had the same resource.Both chlorophyll a and phaeopigments decreased significantly with increasing depth, and would be stable to a certain depth.There are several observed leaps in the vertical distribution of chlorophyll a and phaeopigments,which might reflect the effects of bioturbation.The chlorophyll a and phaeopigments concentration on the surface of sediment varied from 0.14 to 1.17 μg·g^-1 and 0.83 to 5.58 μg·g^-1, respectively,and the mean concentrations in the top centimeter of sediment (0～0.5cm) were 0.54μg·g^-1 for chlorophyll a and 2.45μg·g^-1 for phaeopigments.The spatial distribution of benthic chlorophyll a and phaeopigments were affected by the combination of several factors such as depth (and therefore light) ,temperature, salinity and water content.As the main degradation product of chlorophyll a, phaeopigments became the main type of chlorophyll while increased to certain extent,and acounting for 80～90% of total chlorophyll.Due to the water temperature ,the surface chlorophyll a and phaeopigments concentration varied significantly with the season.Total chlorophyll a in the sediment accounted for 31% of total chlorophyll a in the water column.

Nutrient elements in the atmospheric wet deposition in Changjiang River estuary

ZHANG Guosen, CHEN Hongtao, ZHANG Jing, LIU Sumei

2003, (7):  1107-1111. 

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In order to study the effects of atmospheric wet deposition on red tide,five kinds of nutrient elements were measured with 64 rainwater samples collected at Shengsi Archipelago from May 2000 to April 2001. The results showed that there were obvious differences between monthly average concentrations,due to the different resource and precipitation.The variation of seasonal fluxes suggested that the wet deposition might cause red tide except in winter. The annual concentrations of NO₃^--N, NH₄⁺-N, NO₂^--N, PO₄^3--P and SiO₃^2--Si were 20.23, 30.14, 0.11, 0.045 and 3.43μmol·L^-1,respectively,and their annual fluxes were 2.67×10⁸, 3.98×10⁸, 0.014×10⁸, 0.0059×10⁸ and 0.45×10⁸ mol, respectively. Compared with river input,they were much more smaller.

Nutrients regeneration speed of sediment in harmful algae blooms(HAB) area of East China Sea

QI Xiaohong, LIU Sumei, ZHANG Jing, CHEN Hongtao

2003, (7):  1112-1116. 

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The fluxes of dissolved nutrients at sediment-water interface were investigated at 4 stations in the HAB area of East China Sea in May 2001 and May 2002. The benthic fluxes of nutrients were determined by incubating the sediment core samples with bottom seawater bubbled with air or nitrogen. The transfer of nutrients was more active under anoxic condition. The fluxes of dissolved nutrients were generally high at the stations close to the coast. The sediment was the source of SiO₃^2-, which accounted for 6% of primary production. For DIN and PO₄^3-, the sediment was the sink. DIN and PO₄^3- adsorbed by sediment accounted for 5.9% and 67% of the riverine DIN and PO₄^3- inputs, respectively, and the inputs of SiO₃^2- accounted for 7.8%.

Effects of terrestrial input on the harmful algal bloom area-with aluminum as an example

REN Jingling, LIU Sumei, ZHANG Jing, XIE Liang, LI Dandan, CHENG Yan, ZHU Dedi

2003, (7):  1117-1121. 

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In recent years,eutrophication and frequently occurred harmful algal blooms (HAB) become serious in the coastal area near Changjiang River estuary,and the nutrients came from Changjiang River may be the main sources for them. Aluminum could be used as a useful tracer for the terrestrial input and the movement of different water mass, since it enters into the natural water with the erosion products of soil and rock,and its residence time in the ocean is short and uneasy to be disturbed by the activities of human being. Based on our results,the concentration of dissolved Al was higher in Autumn than in Summer,and showed some relationships with the salinity and suspended particulate matter (SPM). The concentration of Al in the HABarea was higher than0.04 μmol·L^-1, which showed the significant influence from the terrestrial input. The concentration of dissolved Al decreased nearly 40% after the occurrence of HAB, and the flocculation of dissolved Al and its absorption onto the surfaces of biogenic particles might be the main reasons. There still need further study about the variation of Al forms and its mechanism during the occurrence of HAB.

Nutrient distributions and their limitation on phytoplankton in the Yellow Sea and the East China Sea

WANG Baodong

2003, (7):  1122-1126. 

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Based on field observations during1997 to 1999,the distributions of micronutrients and their limitation on the growth of phytoplankton in the Yellow Sea and the East China Sea were discussed in this paper. The results showed that there were abundant nutrients in the area of the east and northern-east of the Changjiang River estuary, and the nutrients came from the extension of the Changjiang River diluted water and the transportation of the Subei Coastal water. Besides, the maximum extension range of the nutrients in the Changjiang River diluted water was observed during the catastrophic flooding period of the Changjiang River in the summer of 1998. Based on the Redfield ratio (Si:N:P=16:16:1) in which,three essential nutrients were utilized by marine phytoplankton, the Si/N/P ratios were calculated and studied for the upper water of the Yellow Sea and the East China Sea. The results indicated that Si/N ratios were very high, which suggested that silicate was not the limiting factor for the growth of phytoplankton in the Yellow Sea and the East China Sea. However, under the influence of terrestrial runoff, especially the Changjiang River runoff which was rich in combined nitrogen and had very high N/P ratios, high N/P ratios occured in the Changjiang River estuary and its adjacent areas such as the south and southwest of the Yellow Sea, the inshore area of the East China Sea and the area east of the Changjiang River estuary in spring and summer. As a result, in contrast to general open marine systems, the systems in these areas resembled estuarine ones rather than typical marine ones. The primary production in a considerable portion of the Yellow Sea and the East China Sea might be limited by phosphate rather than nitrogen.

Temporal dynamics of phytoplankton and nutrients during red tides

QIU Yaowen, ZHU Liangsheng, LI Jinrong, LIANG Song, QI Yuzao

2003, (7):  1127-1130. 

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The relationships between temporal dynamics of phytoplankton density and nutrients (NO₃^-,NH₄⁺,PO₄^3-,SiO₃^2-,Fe) contents in the water body at Aotou waters of Daya Bay during red tide were comprehensively analysed based on the fixed position investigation of red tide in the summer of 2000 and the several years investigation data by using grey linear regression model. The relationships between phytoplankton cell density and chlorophyll a content were also analysed. The results showed that the predicted values were well consistent with the measurement values, and their correlation coefficients were between 0.51～0.83. Red tide might break out if chlorophyll a contents in water body were larger than 5.8 μg·dm^-3. The study could provide a simple effective method to forecast red tide by sampling water samples to analyse chlorophyll a concentration,or using Sea WiFS data,and then,to calculating phytoplankton density. In addition, the primary productivity of the water areas was controlled by phosphorus.

Hydrologic distribution characteristics of HAB frequent occurrence area in the outer Changjiant River estuary

ZHU Dedi, PAN Yuqiu, XU Weiyi, CHEN Qiaoyun

2003, (7):  1131-1134. 

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Based on survey data, this paper analysed the hydrologic characteristics of HABfrequent occurrence area in the outer Changjiang River estuary.The results showed that this area is an area in which the plume front with a salinity of 17～30 in the outer Changjang River estuary,the divergent surface current of the plume front and the upwelling of the high salinity Taiwan bottom warm current are coexisted.In Spring and Summer, the diluted Changjiang River water of this area changed its flow direction under the effect of southwest-northeastward current,possibly due to the large runoff from the Changjiang River to the sea.The upwelling usually occurred at the west side slope between the first turning point and the deep slot top of the outer Changjiang River esturary. This turning point was on the north side in Spring and on the south side in Summer, but in Autumn, no turning point was existed, possibly due to the small runoff. The distribution characteristics of residual current in Spring and Summer was that the adjacent area of plume front was the convergent area of surface and bottom currents,the surface residual current in the upwelling area was at divergent,and the bottom residual current had the characteristics of converging toward the Changjiang River estuary along the deep slot.

Distribution of phytoplankton and water dynamical environmental factors in high red tide occurrence area of Changjiang River estuary

ZHU Genhai, XU Weiyi, ZHU Dedi, SHI Qingsong, ZHANG Jian

2003, (7):  1135-1139. 

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Species composition and cell abundance of phytoplankton, and its relations with environmental factors were investigated in the Changjiang River estuary of east China sea (30°50′～31°50′ N,121°50′～123°00′E). Atotal of 110 taxa belonging to 45 genera of phytoplankton in the investigation area were identified. The main species of phytoplankton resulted in red tide were Skeletonema costatum and Prorocentrum dentatum, etc. Phytoplankton abundance in the day was higher than that at night. The vertical distribution of phytoplankton in different water bodies was not obvious. The ecological groups of phytoplankton were freshwater group, estuarine and brackish water and low salinity group in the coast, high salinity and warm water group in off-sea, and widely ranging group. The abundance of phytoplankton in the Changjiang River estuary was 1.6×10³～75.2×10³ind·dm^-3. The species composition and cell abundance of phytoplankton were related to the freshwater pouring into the Changjiang River estuary. The three waters in the area affecting the distribution of phytoplankton were the Changjiang River estuary water, freshwater, and warm water from outsea.

Response of Prorocentrum minimum growth to zinc limitation

HU Hanhua, SHI Yanjun, CONG Wei, CAI Zhaoling, OUYANG Fan

2003, (7):  1140-1142. 

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Studies on the growth and physiological response of red tide alga Prorocentrum minimum to three Zn ²⁺ levels were showed that the specific growth rate and biomass were limited in low Zn ²⁺-grown cells (1.4 pmol·L^-1, which were 0.40 d^-1 and 51100 cell·ml^-1 respectively. The specific growth rate was not significantly different when the Zn ²⁺ concentration in medium was increased over 24.4 pmol·L^-1,but there was a slight decrease in biomass; however, both specific growth rate and biomass were much higher than those in low Zn ²⁺-grown cells. It was also showed that chlorophyll a synthesis was limited due to Zn ²⁺ deficient,and therefore,the cells became light saturated at higher irradiance under Zn-limited condition. Light-saturated photosynthetic rates (Pm) and photosynthetic efficiency (α) increased significantly with increasing Zn ²⁺ concentrations. It was concluded that Zn ²⁺ concentration might be one of the key factors affecting red tide blooms in eutrophication environment.

Nitrogen and phosphorus absorption and growth characteristics of Alexandrium tamarense

SHI Yanjun, HU Hanhua, MA Runyu, CONG Wei, CAI Zhaoling

2003, (7):  1143-1146. 

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The uptake of nitrate and phosphate by Alexandrium tamarense and its growth characteristics were studied in laboratory cultures, which were conducted using environmentally realistic levels of physical factors during red tide occurrences. The results indicated that the specific growth rate had little difference under three nitrate levels (low-nitrate, 0.0882 mmol稬^-1; middle-nitrate, 0.882 mmol稬^-1; high-nitrate, 2.646 mmol稬^-1).The cell yield was the lowest at low-nitrate, a maximum yield was achieved at the middle-nitrate, which increased by 44.7% and 53.6% respectively,compared with high-nitrate and low-nitrate. The cell yield increased with increasing phosphate concentrations in cultures (low-phosphate, 0.0036 mmol稬^-1; middle-phosphate, 0.036 mmol稬^-1; high-phosphate, 0.108 mmol稬^-1), and the maximum yield (17200 cell穖l^-1) was observed at high-phosphate concentration, while the maximum specific growth rate occurred at middle-phosphate. The growth conditions had a significant effect on the uptake rate of nitrate and phosphate by cells, and the cells grown in low-nitrate and low-phosphate cultures had a higher uptake rate. Further experiment suggested that lower ratio of N/Ppromoted the propagation of cells, and the supplementation of nitrate at later exponential growth phase had a positive effect to the accumulation of biomass.

Distribution and germination of Alexandrium sp.cysts in coastal areas of Southeast China Sea

GU Haifeng, LAN Dongzhao, FANG Qi, WANG Zonglin, CAI Feng

2003, (7):  1147-1150. 

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Studies on the distribution and germination of Alexandrium sp.(A. tamarense+A. catenella) cysts in coastal areas of Southeast China showed that the cysts were only found at X1 and X2 of Xiamen Harbor, whose density was quite low (0.4 ind·g^-1). In Guangxi,the cysts were found at G2 station, with a density of 2.5 ind·g^-1. There were cysts at three stations at Minjiang River estuary. The density reaches maximum value at 4～6cm sediment of M4 station, up to 6 ind·g^-1.In Changjiang River estuary,the cysts distributed widely and had the largest density, up to 23.2 ind·g^-1 at 8～10cm sediment of DG-26 station. The distribution of Alexandrium sp.cysts was relevant to sediment type, sedimentation rate and current. Light had no effect on germination. With increasing temperature, germination and survival rates also increased, while the germination time decreased. Anoxia (0.01mg O₂·L^-1 ) inhibited germination completely.Alexandrium sp. cysts could germinate throughout the year under favorable conditions.

Effects of Alexandrium tamarense and Prorocentrum donghaiense on rotifer Brachionus plicatilis population

WANG Liping, YAN Tian, TAN Zhijun, ZHOU Mingjiang

2003, (7):  1151-1155. 

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The effects of Prorocentrum donghaiense and Alexandrium sp., causative species of harmful algal bloom of East China Sea in May 2002, on rotifer Brachionus plicatilis population were studied in the laboratory. The results showed that Alexandrium tamarense(ATHK) had a lethal effect on B.plicatilis and the 48hLC₅₀ was about 1300 cell穖l^-1. The toxin comparison of different fractions showed that the algal culture and re-suspended algal cells had the adverse effects, and the alga at earlier growth phases showed a stronger impact, indicating that the inhibitory effect was related with the activity of the living algal cells. P.donghaiense at high densities(4?10⁴,5?10⁴ and 10?10⁴ cell穖l^-1) had an adverse effect on B.plicatilis population, while at low densities(1?10⁴,2?10⁴ and 3?10⁴ cell穖l^-1), the alga could be used as food for rotifer population. When the two algae were mixed, the lethal effect of A.tamarense could be decreased by P.donghaiense.The results indicated that the above HAB event could affect the micro-zooplankton population in the occurrence area of East China Sea.

Paralytic shellfish toxins in shellfish from the coast of high frequent harmful algae blooms occurrence areas in East China Sea and South China Sea

JIANG Tianjiu, CHEN Jufeng, ZOU Yinlin, LIU Jiesheng, YANG Weidong

2003, (7):  1156-1160. 

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The paralytic shellfish poisoning (PSP) toxicity levels of shellfish collected from shellfish growing zones in Zhoushan areas of East China Sea and Shenzhen areas of South China Sea during January-November 2002 were determined with AOAC bioassay method. The results showed that the toxicity levels of shellfish from Zhoushan were very low,and few shellfish samples could be detected the PSPtoxicities.The same levels appeared in the shellfish from Shenzhen, but the percentage of shellfish samples contaminated PSP was up to 30%, and the scallop Chalmys nobilis was dominated in the contaminated shellfish species.Analyses on the toxic profiles of digest gland and edible tissue extraction of scallop from Shenzhen showed that a similar suite of toxins presented in the gland and edible tissues.The high potency neo STX and low potency GTX₅ had a high proportions, up to 60.8% and 11.4%,respectively in the tissue, and the high potency GTX ¹⁺² and GTX₅ were the dominant toxins, up to 38.9% and 20%,respectively in the gland. Most of the toxin were accumulated in ingested gland of scallop,and the toxic content in gland was about 8 folds more than that in the edible tissues.

Effects of marine bacteria on the growth and toxin production of red-tide algae under different pH and salinities

SU Jianqiang, ZHENG Tianling, HU Zhong, XU Jingsen, YU Zhiming, SONG Xiuxian

2003, (7):  1161-1164. 

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The effects of strain S₁₀ isolated from sediments of Xiamen Western Sea Area on the growth and paralytic shellfish poison (PSP) production of Alexandrium tamarense at different pHand salinities were studied. The results showed that the alga grew well at pH6～8 and at salinity of 20～34. The toxicity of A. tamarense varied markedly at different pH and salinities:it decreased with increasing pH,while increased with salinity and reached its peak value at the salinity of 30, and then declined. The strain S₁₀ inhibited the growth and the PSP production of A. tamarense at different pH and salinities.It had the best inhibitory function on the growth of A. tamarense at pH7 and salinity of 34. The best inhibitory function on the PSP production of A.tamarense was at pH7, but this inhibitory function was not related to salinity.

Removal of different species of red tide organisms with an effective clay-complex system

SONG Xiuxian, YU Zhiming, GAO Yonghui

2003, (7):  1165-1168. 

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An effective clay-complex system was composed on the base of clay by added other two components Aand B. Different red tide species, such as Scrippsiella trochoidea, Amphidinium carterae and Heterosigma akashiwo, were coagulated by this clay-complex system,and the optimum conditions for removal red tide organisms were obtained by means of orthogonal test. The results showed that clay was the most important factors in this complex system to coagulate these three organisms. The removal efficiency on three species was in order of Scrippsiella trochoidea > Amphidinium carterae > Heterosigma akashiwo. At the same time, a preliminary study of mortality rate on Penaeus japonicus (length between 1.0 to 1.5cm) was conducted with this system,and the result of toxic test revealed that the mortality of aquiculture shrimp in control group (nothing added) reached to 80% after 96h, however,while that of other three groups which added clay and other two components Aand B, was below 40%.Thus,it implied that the addition of clay would be harmless to Penaeus japonicas. Furthermore, suitable concentration of components Aand Bwas not harmful for the aquiculture shrimp, but increased the removal efficiency of red tide organisms. The preliminary results showed that this clay-complex system would be available in the removal of red tide organisms in filed.

Extinguishment of harmful algae by organo-clay

CAO Xihua, YU Zhiming

2003, (7):  1169-1172. 

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Periodic and widespread algal blooms have caused a variety of problems for aquatic life and human activity throughout the world. Currently, the only remedial practice employed for removing algal blooms is to spread clay on the surface of the water.But,the algal removal efficiency by the crude minerals are not really ideal, and how to improve the capability of clays to remove algae is now the technological focus, which also is fatal to the practical value of clays. In this study, hexadecyltrimethyleamine bromide (HDTMAB), one kind of cationic organo-surfactants, was chosen to improve kaolin by surface sorption and cationic exchange, and was tested to remove Prorocentrum donghaiense, a red tide organism in Donghai Sea. The results indicated that organo-clay had an excellent ability to extinguish red tide organisms, even under the application of 0.01g稬^-1, and could subside more than 95% red tide organisms in24h. The efficient algae removal by organo-clay might be from the reversal of the surface electric charge on clay particles, the "net capture" by the long lipoid chains of HDTMAB,and the local high density of HDTMAB on particles surface, which could effectively kill algal cells.

Inhibition and elimination of chlorine dioxide on Phaeocystis globosa

ZHANG Heng, YANG Weidong, GAO Jie, LIU Jiesheng

2003, (7):  1173-1176. 

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Different densities of red tide organism,Phaeocystis globosa(STstrain) were exposed to different concentrations of chlorine dioxide.The results showed that chlorine dioxide could effectively kill and control the algae. When the algae,in the density of 2.35?10⁹ cells稬^-1,was exposured to ClO₂ above 0.74?10^-2 mmol稬^-1,it was inhibited,and eliminated under ClO₂ concentration above 2.96?10^-2 mmol稬^-1. When the density of algae was 2.35?10⁹,1.18?10⁹,4.70?10⁸ and 1.18?10⁸ cells稬^-1,the concentration of chlorine dioxide which could kill the algae efficiently in96 h was 2.96?10^-2,2.22?10^-2,1.48?10^-2 and 0.59?10^-2 mmol稬^-1,respectively. Under the same rate of inhibition or elimination,the higher the density of algae was,the lower the concentration of chlorine dioxide was to effectively control the growth of algae cell,ClO₂ could be considered as a potential algaecide to control red tide.

Povidone-iodine and isothiozolone for removing red tide algae Phaeoecystis globosa

HONG Aihua, YIN Pinghe, ZHAO Ling, HUANG Yunfeng, QI Yuzao, XIE Longchu

2003, (7):  1177-1180. 

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Studies on the removal and control of red tide algae Phaeoecystis globosa by povidone-iodine and isothiozolone algaecide showed that Phaeoecystis globosa could be killed and controlled by povidone-iodine and isothiozolone. The effective concentration of povidone-iodine was 30 mg稬^-1, and that of isothiozolone was 0.30 mg稬^-1. Using povidone-iodine and isothiozolone together could improve the effect, and the ideal composite ratio of povidone-iodine and isothiozolone was 1.0:0.15.

Spectroscopic properties of Heterosigma akashiwo under iron limitation

LI Dongxia, CONG Wei, CAI Zhaoling, SHI Dingji, OUYANG Fan

2003, (7):  1181-1184. 

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Room-temperature absorption spectra of H. akashiwo cells under iron limitation showed a chlorophyll c absorption peak at 630 nm, 2 nm blue-shifted from its normal position of 632 nm. Moreover, because of the increase in the relative carotenoid abundance compared to Chl a, there was an extra shoulder peak at 480 nm for the iron-limited cells. Their fluorescence spectra (77 K) have one prominent chlorophyll emission peak at 685 nm. By comparison with Fe-replete cells (10 μmol·L^-1), the fluorescence yield from 685 nm band increased by about 2 times in Fe deplete cells (5 nmol·L^-1),and about 1.4 times in low iron cells (100 nmol·L^-1),respectively. 48 h after Fe addition, the height of 685 nm peak was considerably decreased from that observed in low iron (100 nmol·L^-1) and iron deficient (ID) cells before Fe addition,which indicated that there was a significantly higher energy dissipation, and thus,a less effective photosynthesis under the lack of Fe.

Induction of biochemical composition in Heterosigma akashiwo under Fe stress

LI Dongxia, CONG Wei, CAI Zhaoling, SHI Dingji, OUYANG Fan

2003, (7):  1185-1187. 

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The iron-stress mediated effects on biochemical constituents of red tide alga H. akashiwo were examined in Fe-replete and iron deficiency,and low iron batch cultures. The content of all pigments decreased under iron limitation,and the cellular chlorophyll a concentration decreased by more than 2-fold compared to that under iron replete condition. This change in Chl a was accompanied by a corresponding decrease in Chl c per cell, resulting in no trend in the ratio of Chl c to Chl a. The cellular carotenoids content decreased by more than1.5-fold compared to that under iron replete condition. As a consequence, carotenoids/chlorophyll a ratio increased in Fe-deficient cells. Carbohydrate content was reduced under iron stress,and total proteins decreased with the decrease of iron concentration. Acrude fractionation of the soluble proteins demonstrated that 17 kDand 55 kDa proteins in soluble fraction were induced.

What the Prorocentrum species should be? -A review on identification of a Prorocentrum species from the East China Sea

QI Yuzao, WANG Yan

2003, (7):  1188-1190. 

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In the past decade, the Prorocentrum bloom was the most frequently occurred bloom in the East China Sea. It occurred every one year or two years, and covered huge areas. There were arguments on the identification of Prorocentrum bloom causative species. Some scientists thought the species being P. dentatum Stein, but the others thought that it was a new species, P. donghaiense Lu. For achieving the proper classification of the species, an "International Workshop on HAB Causative Species-Taxonomic View on a species of Prorocentrum in the East China Sea" was held in Shenzhen, China in November, 2002. By reviewing as much as available references, and by comparing the Prorocentrum specimen from the East China Sea with those from Japan, Korea and USA, scientists participated in this Workshop agreed that: 1) the specimens from Japanese and Korean waters, and from CCMP, USA were the same species; 2) the features of anterior projection and cell surface marking were similar to those of originally described P. dentatum Stein; 3) the major difference is the cell size. The specimens from the East China Sea were mostly less than20 μm long, whereas the size of the original described P. deatatum was larger than 50 μm; 4) the minor difference is the shape of the cell end. The original described P. deatatum was with a pointed end, whereas the cells from the East China Sea were mostly with a rounded end. There was no final agreement for the species identification at the Workshop. By summing all views of scientists from the Workshop, the authors suggested that the bloom causative species of Prorocentrum in the East China Sea, as well as so-called species of P. dentatum from other East Asian waters, should be the same species. They are all P. donghaiense Lu.

Research advance in effects of harmful algal bloom species on zooplankton

WANG Liping, YAN Tian, TAN Zhijun, ZHOU Mingjiang

2003, (7):  1191-1196. 

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The research on the effects of harmful algal bloom (HAB) algae on zooplankton has been drawn more and more attention. This paper summarized the adverse effects of HABalgae on zooplankton,which included reduced survival,inhibited growth,reduced fecundity of female, fertilization failure of eggs or hatching failure of zygote,inhibited embryo development,naupliar abnormal development or abnormality,inhibited grazing and changed behavior of zooplankton, etc. The main intoxication ways included decreased utilization of food,physiology impairment,damaged cell membrane,reduced gamete quality,and inhibited mitotic and embryo development by phycotoxins or exudations released by algae. Additionally, the lack of full nutrition,especially of polyunsaturated fatty acids in some algal species cells could also affect zooplankton growth and reproduction.

Advances in researches of aquatic ectoenzyme and its relationship with red tide

OU Linjian, HUANG Bangqin, HONG Huasheng, WANG Dazhi

2003, (7):  1197-1199. 

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Ectoenzymes play an important role in the material cycle and energy conversion in aquatic ecosystem. The researches of ectoenzyme are of significance in further understanding the marine carbon biogeochemical cycle and the countermeasures of algae under bloom conditions.In this paper, the research methods, characteristic activity and size distribution, controlling factors and their ecological significances of algal ectoenzymes were reviewed, and ectoenzyme introduced as one kind of new trophic state index.

Algorithms of multiband remote sensing for coastal red tide waters

MAO Xianmou, HUANG Weigen

2003, (7):  1200-1202. 

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The spectral characteristics of the coastal waters in East China Sea was studied using in situ measurements,and the multiband algorithms of remote sensing for bloom waters was discussed and developed. Examples of red tide detection using the algorithms in the East China Sea were presented. The results showed that the algorithms could provide information about the location and the area coverage of the red tide events.

Spectrophotometer detection of benzalkonium bromide concentration in seawater

PAN Jianyu, YIN Pinghe, ZHAO Ling, QI Yuzao, XIE Longchu

2003, (7):  1203-1204. 

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Benzalkonium bromide is a high-efficiency algaecide.Its concentration in seawater was measured by the method of spectrophotometer. The results indicated that the deposition appeared if the concentration of benzalkonium bromide in seawater was more than 50mg稬^-1,and affected the detection of benzalkonium bromide.But,there was a good linear relationship between concentration and absorbance when the concentration was lower than 50mg稬^-1 (R²=0.9996). Therefore,spectrophotometer could be used to detect benzalkonium bromide in seawater.