Studies On Seasonal Distribution And DNA Fingerprint Of Phytoplankton Community In Daya Bay

Annual survey on phytoplankton community and environmental factors was carried out inDaya Bay from December2010to November2011. DNA fingerprint and genetic diversity ofphytoplankton were analyzed by PCR-DGGE. The purpose of this study is to reveal seasonalvariation of phytoplankton community structure, and to provide background information forenvironmental protection and red tide control in Daya Bay.Results showed that diatom was the main phytoplankton group, followed by dinoflagellate. Atotal of93phytoplankton taxa were identified in this survey. Forty eight taxa were observed inwinter samples. The dominant species of diatoms were Guinardia striata and Skeletonemacostatum, while Scrippsiella trochoidea was the dominant dinoflagellate in winter. Forty threetaxa were observed in spring samples, in which Chaetoceros spp. and Skeletonema costatumwere dominant diatoms, and Akashiwo sanguina was dominant dinoflagellate. Forty two taxaof phytoplankton were observed in summer samples, with the dominant diatoms of Chaetocerosspp., Leptocylindrus danicus, and Pseudo-nitzschia, the dominant dinoflagellate of Scrippsiellatrochoidea. Forth nine taxa were observed in autumn. The dominant diatoms werePseudo-nitzschia spp., Skeletonema costatum and Thalassionema nitzschioides, and thedominant dinoflagellate was Scrippsiella trochoidea. Species richness of dinoflagellates washigher in spring than those in the other three seasons. The cell numbers of phytoplankton variedgreatly among stations with remarkable seasonal variations. Cell numbers in summer were thehighest, next to autumn, and then winter and spring. While species richness was highest inautumn, next was winter, and species richness was lower in spring and summer. The number ofphytoplankton species in each station was comparable among stations, and generally speciesnumbers were higher in S2, S3and S9. The values of species diversity index and evenness werecomparable among stations as well.Fingerprints of18S rDNA V3region of single species and multi-species of seven harmfulalgal bloom (HAB) taxa were studied by denaturing gradient gel electrophoresis (DGGE). Anature sample from the Cochlodinium geminatum bloom in Zhuhai coasts in October2009wasanalyzed as well. Results showed that distinguish lanes appeared in DGGE fingerprints by theseven HAB species including Gyrodinium instriatum, Prorocentrum micans, Akashiwosanguinea, Scrippsiella trochoidea, Skeletonema costatum, Alexandrium tamarense andCochlodinium geminatum. Meanwhile four dominant species (Cochlodinium geminatum,Akashiwo sanguinea, Gyrodinium instriatum and Prorocentrum micans) were observed infingerprint of the bloom sample, which were consistent with the microscopical observation. As the same with the microscopic observation, DGGE fingerprint bands of phytoplanktonwere higher in summer and autumn, and less in spring and winter. Similarity analysis ofphytoplankton DGGE fingerprints showed that S1and S3were always clustered to one groupwith high similarity, which was consistent with the clustering results of observational data ofphytoplankton. DGGE profiles of dinoflagellates were significantly lower than those of totalphytoplankton, which was same with the results of its second largest groups of phytoplanktonunder the microscopical observations. The results suggested that DNA fingerprinting ofphytoplankton using PCR-DGGE could reflect the phytoplankton community structure andphytoplankton diversity to some extents.