Ecological characteristics of phytoplankton in the Laizhou Bay

Phytoplankton is the primary producer of marine organisms,which not only acts as the first producer absorbing nutrients,but also as the food organisms ingested by the zooplankton and large filter-feeding animals.It plays an important role in the material circulation and energy of the ocean ecosystem exchange.In addition,phytoplankton as the primary producer of ocean ecosystem,its community similarity and diversity's changes will affect the makeup and function of ocean ecosystem directly.N and P are the foundation which phytoplankton lives on,and its content and distribution affect the number of phytoplankton deeply.Otherwise,the number of N and P absorbed by the phytoplankton also affect the content of the nutrients in some way,so it is high time for us to deeply research the correlation between the phytoplankton and the nutrients.This paper reported the results of the biological characteristics,biomass,species composition,and community structure of phytoplankton in the Laizhou Bay,analyzed the community similarity,the relation between phytoplankton's distribution and the nutrients.The results showed that there were 22 genus 45 species phytoplankton in the investigational area.Among them 20 genus 45 species were Bacillariophyta,accounted for 88.9%,and 2 genus 5 species were Pyrophyta,accounted for 11.1%.The mean value of the total number of phytoplankton was 0.16×10~(4)-20642.83×10~(4) cell/m~(3).The maximum appeared in August 2003 and its minimum appeared in May 2003.Compared with the information of history,there was a declining tendency for the phytoplankton species of the Laizhou Bay in number.Four indexes which were diversity index,abundance index,simplicity index and evenness index were used to analyze the characteristics of community structure of phytoplankton in the investigational area.The results showed that the diversity and abundance indexes were better in Laizhou Bay;the characteristics of community structure of phytoplankton were steady.On the whole,there was a positive correlation between phytoplankton and temperature,and there was a negative correlation between phytoplankton and salinity.But the correlation between phytoplankton and a certain nutrients wasn't obvious.