| The chemotaxonomy based on pigment is a powerful tool to classify marine phytoplankton. It is convenient to analyze numbers of samples continuously. It is the method of choice for researching the variation of phytoplankton community structures and undergoing marine ecological investigation macroscopically. The knowledge of marine phytoplankton compositions could be enriched by finding nanoplankton and picoplankton species based on pigment analysis which may not be observed by traditional method.A classical HPLC pigment analysis method was selected and a series of quality assurance procedures were employed to insure accurate and precise results. Qualitative and quantitative analysis of pigments in surface seawater samples collected from Dec. 2003 to Oct. 2004 in Jiaozhou Bay, China were made based on this validated method. 33 kinds of pigments were detected in 123 samples. The major pigments were chlorophyll a, fucoxanthin, peridinin, chlorophyll b, zeaxanthin, 19'-hexanoyloxyfucoxanthin, 19'-butanoyloxyfucoxanthin, prasinoxanthin and alloxanthin. 8 phytoplankton classes were estimated in these samples according to the pigments detected: diatoms, dinophyceae, chlorophyceae, chrysophyceae, haptophyceae, cyanobacteria, prasinophyceae and cryptophyceae.Among the mathematical algorithms in phytoplankton chemotaxonomy, it was found that the method of matrix factorization which is represented by CHEMTAX has the quality of calculating all phytoplankton classes, convenience and outputting reasonable results. The influence of input pigment ratios, phytoplankton classes' initialization and the structure of pigment ratio matrix to the output results of CHEMTAX were discussed, and the calculated results of phytoplankton community structure of Jiaozhou Bay were obtained in these processes. It was showed that the major phytoplankton in Jiaozhou Bay is diatoms, cryptophyceae and prasinophyceae.The sum of the average contribution of chlorophyll a of these three classes is 90%. Diatoms are the most important class in Jiaozhou Bay. The average contribution of diatoms to chlorophyll a pool is 70%.Two peaks of its chlorophyll a contribution were formed in winter (Feb. 2004) and spring (May 2004), and the value was 85% and 77% respectively. The spatial distribution of chlorophyll a contribution of diatoms is characterized by the higher value area in shore and lower value area in northwest of investigating sea area. The lower value area has the trend of extending from the mouth of the bay near the southeast shore to the central section of the bay, especially in the month of season conversion. The temporal and spatial distribution characters were matched with the historical trend.12 species (14 strains) of cultured diatoms were selected for the preliminary study of classifying of diatoms through the combination of diagnostic pigment ratios in this research. 3 pigment ratios, i.e. chlorophyll c-i\ chlorophyll c\, focoxanthin: total chlorophyll c and diadinoxanthinrdiatoxanthin, were found by cluster analysis and discrimination analysis. 12 diatom species were classified into 4 groups which are matched with the biological classification basically. A new road to the classification of phytoplankton was provided by this method.Prasinophyceae containing prasinoxanthin is a kind of ultraplanktonic photosynthetic eukaryotic algae which is very important in the primary production of the coastal sea area. Prasinoxanthin is its diagnostic pigment and can be used to judge its presence and calculate the abundance. The diagnostic pigments of prasinophyceae were detected for the first time in Jiaozhou Bay and this is the first time in China seas too. The existence of Micromonas pusilla which was discovered before in Jiaozhou Bay was recognized by molecular biological experiment. Large quantities of 2-5um diameters, spherical, without flagellum and draped in different degree were found by SEM. It was judged synthetically that ultraplanktonic prasinophyceae containing prasinoxanthin in Jiaozhou Bay were mainly 2-5um diameters coccoid species, the possible genus are Ostreococcus, Prasinococcus, Pycnococcus, Prasinoderma and Micromonas. The contribution of them to total chlorophyll a was estimated by the ratio of prasinoxanthin to chlorophyll a reported in a literature. The average-4-contribution of ultraplanktonic prasinophyceae containing prasinoxanthin to the total chlorophyll a pool is 8.5% and 17.0% in May 2004 and Aug. 2004 respectively, and the highest value is 25.9% and 36.3% respectively in certain stations. 80% of prasinoxanthin were found existed in the size fraction of 2-20u.m, and more than 50% of chlorophyll a of under 20u.m fraction were contributed by ultraplanktonic prasinophyceae containing prasinoxanthin. The contribution of this highly abundant phytoplankton which is ignored in traditional biological investigation to primary production in coastal sea area is existed for a certainty and could cause significant influence. It deserves further research.
|
PDF Full Text Request