Studies On Biodiversity And Ecology Of Phytal Fauna With Molecular Identification

The phytal fauna on the seaweed Sargassum thunbergii was surveyed monthly over an annual cycle from November 2007 to October 2008 in the rocky intertidal zone in Taipingjiao, Qingdao. The phytal fauna on Grateloupia filicina, Chondrus ocellatus, Gymnogongrus flabelliformis, Sargassum palladium and Amphiroa zonata were also surveyed based on their growing periods. Dominant group, abundance, biomass, community structure and species diversity of phytal fauna are analyzed. The community structure and biodiversity of intertidal polychaetes were also studied with molecular identification. This is the first investigation of the phytal fauna community structure and biodiversity in twelve months systematically. It is also novel to conduct an integrated study of the systematics and ecology of phytal fauna with molecular identification.1. Sixteen faunal groups are identified from the 6 seaweeds in total. The annual average abundance of the phytal fauna is 606 inds./g dwt algae on Sargassum thunbergii. Nematodes and copepods are the most dominant, followed by gastropods and polychaetes. The abundance of April is the highest, July is the lowest. In terms of biomass, the annual average is 282×103μg/g dwt algae and the most dominant group is gastropods, followed by polychaetes and amphipods. The biomass of June is the highest, the lowest number is in February. Numbers of phytal fauna groups, abundance and biomass on Sargassum thunbergii are higher than on other seaweeds. The dominant group among months and seaweeds are different. Abundance and biomass of phytal fauna had no significant correlation with environmental factors, but the abundance of nematodes are significantly correlated with temperature and DO. The complexity of algal growth form is possibly the main determinant of faunal composition and seasonal succession.2. A total of 36 species or morpho-species of nematodes are identified on Sargassum thunbergii.Three distinct nematode community groups are recognized, July exhibits lowest nematode abundance, fewest species and lowest diversity. It is dominated by Eurystomina ophthalmophra. August, September and October exhibits higher nematode abundance, more species and higher diversity, the dominant species is Eurystomina ophthalmophra. Other months forms the third community group with the species and biodiversity between the first two groups and Enoplus cf. communis is the dominant species. Correlation analysis between diversity indices and environmental variables indicate that the number of nematode species S and Shannon-Wiener index H' is positively correlated (P<0.01), while Pielou's evenness J'and the salinity is negatively correlated (P<0.05).3. Investigates the validation of CO1 gene sequence as a DNA barcode in classification of the intertidal benthic polychaetes and also investigated the species composition and community structure of intertidal polychaetes in Qingdao. Combining morphological characteristics and 16S rDNA, some of the species living on the coast of Qingdao were assessed for their taxonomic position. In this study,22 hyplotype gene sequences of 13 polychaete species, including 10 CO1 sequences and 12 16S rDNA sequences were obtained. Sequence analysis was conducted by using MEGA4.0 software. Intra-and inter-specific distances were calculated and based on these distances, phylogenetic relationships were inferred using neighbor-joining method. The results of DNA barcoding based on the mitochondrial CO1 gene in the identification of polychaetes are basically convergent with those of morphology and 16S rDNA analysis. This study suggest that mitochondrial CO1 gene is a valid DNA barcoding gene for specie identification in polychaetes, but other genes like 16S rDNA could be used as a complementary genetic marker. For more accurate specie identification, DNA barcoding study should be integrated with morphological, zoogeographical, ecological and phylogenetic information. DNA barcoding of intertidal polychaete communities is one of the possible ways for the integrated study.