The source and significance of two nutrients,nitrogen and phosphorous,were investigated by a modified dilution method performed on seawater samples from the Jiaozhou Bay,in autumn 2004.This modified dilution method accounted for the phytoplankton growth rate,microzooplankton grazing mortality rate,the internal and external nutrient pools,as well as nutrient supplied through remineralization by microzooplankton.The results indicated that the phytoplankton net growth rate increased in turn from inside the bay,to outside the bay,to in the Xiaogang Harbor.The phytoplankton maximum growth rates and microzooplankton grazing mortality rates were 1.14 and 0.92 d^-1 outside the bay,0.42 and 0.32 d^-1 inside the bay and 0.98 and 0.62 d^-1 in the harbor respectively.Outside the bay,the remineralized nitrogen (K_r=24.49) had heavy influence on the growth of the phytoplankton.Inside the bay,the remineralized phosphorus(K_r=3.49) strongly affected the phytoplankton growth.In the harbor,the remineralized phosphorus (K_r=3.73) was in larger demand by phytoplankton growth.The results demonstrated that the different nutrients pools supplied for phytoplankton growth were greatly in accordance with the phytoplankton community structure,microzooplankton grazing mortality rates and environmental conditions.It is revealed that nutrient remineralization is much more important for the phytoplankton growth in the Jiaozhou Bay than previously believed.

Based on the data of the Jiaozbou Bay Ecosystem Dynamic Research,cell volume and surface area of 87 common phytoplankton species in China sea waters were calculated with assignment of the similar geometric form.The cell plasma volume,live weight,carbon mntent and nitrogen content were also calculated with the methods of Mullin et al.(1966),5trathmann(1967),Eppley et al.(1970),arid Taguchi(1976).After comparing these methods,we chose the method of Eppley et al.(1970) as the best method for calculating phytoplankton carbon content in China sea waters.

Long-term changes of phytoplankton community by water sampling method in Xiagu Sea waters of Xiamen, China, were investigated in this study. Species composition of the phytoplankton community in these waters changed greatly since the 1950s. The numbers of Dinophyta species increased significantly, although Bacillariophyta species are generally dominant. The succession of dominant species in phytoplankton community is obvious:large-size dominant species such as Biddulphia sinensis of the 1950s were gradually replaced by small-size ones such as Cyclotella striata and Nitzschia closterium, and species that still maintain dominant such as Skeletonema costatum are also small ones, leading the whole phytoplankton community of smaller size. Cell density of phytoplankton community increased greatly, among which cell density of the most dominant species Skeletonema costatum have been increasing in exponent function. Margalef index of phytoplankton community decreased, indicating decline of biodiversity of the community, and dominant character of Skeletonema costatum increased. Generally, the structure of the entire phytoplankton community is becoming more and more singular and unstable, which makes the occurrence of red tides more frequent. The succession in the phytoplankton community is related to the long-term changes in marine environment, influenced by human activities and global climate changes, especially the increases of nutrient content.

The results from the 38 cruises of phytoplankton surveys in the red tide outburst area in the Xiamen Harbor in 1987 indicate 41 species of red tide organisms among 110 species of phytoplankton identified.Species tomposition was dominant by eurytopic species and warm water species.Species diversity apparently changed with (cold and warm) seasons.There was a high diversity in warm seasons, 63 species in August.Average annual number of phytoplankton reached 1 119×10³ ind./dm³ which was 2 to 2.6 times that in 2 control monitoring stations.The number of phytoplankton in horizonal distribution displayed an obvious increasing tendency from the harbour mouth to the inner harbor.The phytoplankton number always changed with time, but with 3 peak values in the year round.The daily change of the phytoplankton number with tide exhibited a negative relativity.Moreover phytoplankton species and their number showed a vertical movement during day and night.Futhermore, 10 predominant species changed with seasons was noted in the present paper.

Remote sensing applications are important in the fisheries sector and efforts were on to improve the predictions of potential fishing zones using ocean color. The present study was aimed to investigate the phytoplankton dynamics and their absorption properties in the coastal waters of the southeastern Arabian Sea in different seasons during the year 2010 to 2011. The region exhibited 73 genera of phytoplankton from 19 orders and 41 families. The numerical abundance of phytoplankton varied from 14.235×10³ to 55.075×10⁶ cells/L. Centric diatoms dominated in the region and the largest family identified was Thalassiosiraceae with main genera as Skeletonema spp., Planktionella spp. and Thalassiosira spp. Annual variations in abundance of phytoplankton showed a typical one-peak cycle, with the highest recorded during premonsoon season and the lowest during monsoon season. The species diversity index of phytoplankton exhibited low diversity during monsoon season. Phytoplankton with pigments Chlorophyll a, Chlorophyll b, Chlorophyll c, peridinin, diadinoxanthin, fucoxanthin, β-carotene and phycoerythrobilin dominated in these waters. The knowledge on phytoplankton dynamics in coastal waters of the southeastern Arabian Sea forms a key parameter in bio-optical models of pigments and productivity and for the interpretation of remotely sensed ocean color data.

Phytoplanktonic ecological provinces of the Yellow Sea (31.20°-39.23°N, 121.00°-125.16°E) is derived in terms of species composition and hydrological factors (temperature and salinity). 173 samples were collected from 40 stations from April 28 to May 18, 2014, and a total of 185 phytoplanktonic algal species belonging to 81 genera of 7 phyla were identified by Utermöhl method. Phytoplankton abundance in surface waters is concentrated in the west coast of Korean Peninsula and Korea Bay, and communities in those areas are mainly composed of diatoms and cyanobacteria with dominant species ofCylindrotheca closterium, Synechocystis pevalekii, Chroomonas acuta, Paralia sulcata, Thalassiosira pacifica and Karenia mikimotoi, etc. The first ten dominant species of the investigation area are analyzed by multidimensional scaling (MDS) and cluster analysis, then the Yellow Sea is divided into five provinces from Province I (P-I) to Province V (P-V). P-I includes the coastal areas near southern Liaodong Peninsula, with phytoplankton abundance of 35 420×10³-36 163×10³ cells/L and an average of 35 791×10³ cells/L, and 99.84% of biomass is contributed by cyanobacteria. P-Ⅱ is from Shandong Peninsula to Subei coastal area. Phytoplankton abundance is in a range of 2×10³-48×10³ cells/L with an average of 24×10³ cells/L, and 63.69% of biomass is contributed by diatoms. P-Ⅲ represents the Changjiang (Yangtze River) Diluted Water. Phytoplankton abundance is 10×10³-37×10³ cells/L with an average of 24×10³ cells/L, and 73.14% of biomass is contributed by diatoms. P-IV represents the area affected by the Yellow Sea Warm Current. Phytoplankton abundance ranges from 6×10³ to 82×10³ cells/L with an average of 28×10³ cells/L, and 64.17% of biomass is contributed by diatoms. P-V represents the cold water mass of northern Yellow Sea. Phytoplankton abundance is in a range of 41×10³-8 912×10³ cells/L with an average of 1 763×10³ cells/L, and 89.96% of biomass is contributed by diatoms. Overall, structures of phytoplankton community in spring are quite heterogeneous in different provinces. Canonical correspondence analysis (CCA) result illustrates the relationship between dominant species and environmental factors, and demonstrates that the main environmental factors that affect phytoplankton distribution are nitrate, temperature and salinity.

The results of an investigation carried out during June 2005 to May 2007 on physico-chemical parameters, species composition and community structure of phytoplankton including Chlorophyll a (Chl-a) at the Coleroon coastal waters (Southeast coast of India) are reported. Air and surface water temperatures (℃) varied from 25.1 to 30.1 and from 24.5 to 28.5 respectively. Salinity values varied from 6 to 28.5 and the pH ranged between 7.0 and 8.3. Variation in dissolved oxygen content was from 3.1 to 7.5 mg/dm³ while the light extinction coefficient values (LEC) ranged between 3.1 and 10.1 cm. The ranges of inorganic nutrients (μmol/dm³) viz., nitrate, nitrite, phosphate and silicate were 10.1-23.4, 1.2-8.9, 0.2-3.1 and 55-125, respectively. The ranges of Chlorophyll a (μg/dm³) values was 2.0-7.5. Presently, 124 phytoplankton species representing different classes viz:Bacillariophyceae (77), Dinophyceae (19), Cyanophyceae (15), Chlorophyceae (10) and Chrysophyceae (3) were recorded. The phytoplankton cell abundance varied from 0.290 to 111.662 cells/cm3, with peak diversity (3.38 bits/ind.) during summer season. The maximum abundance was found during summer season coinciding with the stable hydrographical conditions. The seasonal distribution and abundance of phytoplankton are discussed in relation to hydrographical parameters. Canonical Correspondence Analysis (CCA) was applied in this paper for discriminating environmental factors having effect on phytoplankton community at species level. Coleroon coastal water is subjected to long term fluctuations in physico-chemical parameters depending upon the seasonal tidal amplitude and freshwater influx resulting in a continuous exchange of organic, inorganic, plant and animal matters.

The Yellow Sea is located between the China Mainland and the Korean Peninsula, representing a typical shallow epicontinental sea. The Yellow Sea Cold Water Mass (YSCWM) is one of the most important physical features in the Yellow Sea. The characteristics of vertical profiles and seasonal variations of biogenic elements in the YSCWM may lead the variations of nutrient availability (e.g., phosphorus) and phosphorus stress of phytoplankton. In this study, the authors surveyed the seasonal variations of phytoplankton phosphorus stress with emphasis on the effect of the YSCWM during the four cruises in April and October 2006, March and August 2007. Using both bulk and single-cell alkaline phosphatase activity (APA) assays, this study evaluated phosphorus status of phytoplankton community, succession of phytoplankton community and ecophysiological responses of phytoplankton to phosphorus in the typical region of the YSCWM. With the occurrence of the YSCWM, especially the variations of concentration of dissolved inorganic phosphorus (DIP), the results of bulk APA appeared corresponding seasonal variations. Along Transects A and B, the mean APA in August was the highest, and that in March was the lowest. According to the ELF-labeled assay’s results, seasonal variations of the ELF-labeled percentages within dominant species indicated that diatoms were dominant in March, April and October, while dinoflagellates were dominant in August. During the four cruises, the ELF-labeled percentages of diatoms except Paralia sulcata showed that diatoms were not phosphorus deficient in April 2006 at all, but suffered from severe phosphorus stress in August 2007. In comparison, the ELF-labeled percentages of dinoflagellates were all above 50% during the four time series, which meant dinoflagellates such as Alexandrium and Scrippsiella, sustained perennial phosphorus stress.

Analysis of high-resolution 4 km sea surface temperature, Chlorophyll a (Chl a), and wind datasets provides a detailed description of the spatio-temporal seasonal succession of phytoplankton biomass in the Red Sea and Gulf of Aden. Based on Moderate Resolution Imaging Spectroradiometer on-board aqua platform (MODIS Aqua) data andsynoptic observations in the Red Sea, Chl a varies from north to south, with the northern part appearing to be oligotrophic. This is likely due to the absence of strong mixing and low nutrient intrusion in comparison to the southern part during winter. In the Gulf of Aden, the emergence of upwelling cell is clearly evident along the coast of Yemen, and is only distinct from the summer-autumn seasons. Most notable is the pulsating nature of the upwelling, with warm and cold events clearly distinguished with phytoplankton response to this physical forcing also evident. The phytoplankton biomass distribution varies considerably between the two regions of study. In both study areas, water temperature and prevailing winds control nutrient concentrations.

The West Pacific Ocean is considered as the provenance center of global marine life and has the highest species diversity of numerous marine taxa. The phytoplankton, as the primary producer at the base of the food chain, effects on climate change, fish resources as well as the entire ecosystem. However, there are few large-scale surveys covering several currents with different hydrographic characteristics. This study aimed to explore the relationships between the spatio-temporal variation in phytoplankton community structure and different water masses. A total of 630 water samples and 90 net samples of phytoplankton were collected at 45 stations in the Northwest Pacific Ocean (21.0°–42.0°N, 118.0°–156.0°E) during spring and summer 2017. A total of 281 phytoplankton taxa (>5 μm) belonging to 61 genera were identified in the study area. The distribution pattern of the phytoplankton community differed significantly both spatially and temporally. The average abundances of phytoplankton in spring and summer were 797.07×10² cells/L and 84.94×10² cells/L, respectively. Whether in spring or summer, the maximum abundance always appeared in the northern transition region affected by the Oyashio Current, where nutrients were abundant and diatoms dominated the phytoplankton community; whereas the phytoplankton abundance was very low in the oligotrophic Kuroshio region, and the proportion of dinoflagellates in total abundance increased significantly. The horizontal distribution of phytoplankton abundance increased from low to high latitudes, which was consistent with the trend of nutrient distributions, but contrary to that of water temperature and salinity. In the northern area affected by the Oyashio Current, the phytoplankton abundance was mainly concentrated in the upper 30 m of water column, while the maximum abundance often occurred at depths of 50–75 m in the south-central area affected by the Kuroshio Current. Pearson correlation and redundancy analysis (RDA) showed that phytoplankton abundance was significant negatively correlated with temperature and salinity, but positively correlated with nutrient concentration. The phytoplankton community structure was mainly determined by nutrient availability, especially the N:P ratio.