Community Structure Of Invertebrate Resting Eggs In Sediments Of Fujian Coasts And Xiapu Freshwater Wetlands

Dormancy is a survival strategy adopted by many invertebrates under harsh environmental stress,and producing resting eggs is one of the forms of dormancy in invertebrates.In this study,sediments of Fujian coastal and Xiapu freshwater wetlandss were sampled to explore the diversity and distribution of invertebrate resting eggs in sediments on regional scale and local scale and the correlation between environmental factors of habitat and community structure of resting eggs,aiming to provide fundamental scientific data for exploring the distribution pattern of resting eggs in sediments of China and for illuminating coping mechanism of invertebrates for different habitats.Eleven sediment samples were collected from Fujian coasts in this study.At the same time,five rivers and five ponds were randomly selected in Xiapu freshwater wetlands,Fujian Province.The resting eggs in sediment were isolated by "sucrose suspension" method.I used "Hot Shot" method for DNA extraction of the resting eggs and LCO1490 and HCO2198 for polymerase chain reaction amplification(PCR)of a 710 bp fragment of the mitochondrial cytochrome c oxidase subunit ? gene(mt CO?).Combing molecular information and morphological features,community structure of invertebrate resting eggs in sediment was revealed by counting resting eggs of different species.The main findings were as follows:(1)Nearly 4000 morphological images of resting eggs of various groups were collected and 1000 mt CO? sequences were successfully obtained.Two hundred and nine species of resting eggs were successfully identified,including 37 species of copepods,27 species of Cladocera,45 species of rotifers and 100 species of other species.(2)The abundance and richness of resting eggs were generally low in sediment on the Fujian coasts,and the dominant species were Labidocera rotunda,Acartia pacifica,Acartia erythraea,Centropages tenuiremis,Synchaetidae 3,Caenidae.Ecological parameters including Shannon-Wiener diversity index,species richness and species abundance of resting eggs were measured.The former two were significantly correlated with p H of deep water,salinity of shallow water and salinity of deep water.In addition,there was a significant correlation between p H of sediment and richness of resting eggs,but community structure of resting eggs was independent of latitude position of sampling points in sediment on the Fujian coasts.(3)The abundance and richness of resting eggs in sediments of Xiapu freshwater wetlands were much higher than those in coasts.There was no widespread dominant species,besides the abundance and richness of resting eggs in river were lower than those in the pond.Although geographical locations of the sampling sites in Xiapu freshwater wetlands were similar,most of the environmental factors among the sampling sites were different.This may be because of human activities and environmental pollution.Based on Pearson correlation analysis,there was significant positive correlation between abundance of resting eggs and content of Chlorophyll a and Pheophorbide a in sediment,and a negative correlation between Shannon-Wiener diversity index of resting eggs and salinity of water samples.In summary,there were significant differences of species composition and distribution of resting eggs between Xiapu freshwater wetlands and Fujian coasts.Meanwhile,community structure of resting eggs was significantly correlated with some environmental factors,such as water salinity,water p H,content of Chlorophyll a and Pheophorbide a in sediment.And further more,different ecological parameters correlated with different environmental factors in different habitats.In addition,a large number of images of resting eggs in sediment were obtained,which can be of great value for establishing a morphological catalogue of resting eggs and quickly identifying the species of resting eggs.