Multivariate Statistical Analysis Of Plankton And Environmental Factors In The Artificial Reef Area Of Bohai Bay

Bohai Bay is a typical semi-enclosed gulf located in the west of the Bohai Sea.Due to the weak hydrodynamic,pollutants were hard to transport and diffuse out of the gulf.Since2000,with the rapid development of the Bohai Sea region economy,especially the boom of the port,coastal industrial,marine aquaculture industry,a large quantity of sewage,deterioration of water quality in coastal waters,serious eutrophication and red tide disasters has come one after another,so that the ecological environment has been under severe stress.In order to know the ecological status of artificial reef area of Bohai Bay,sampling investigations were conducted which included plankton status and environmental factors for three consecutive years.This study focused on the spatial and temporal distribution of plankton and environmental factors,further the relation between them.The main results were as follows:All the environmental factors in the water showed a distinct seasonal distribution,which was higher in August,but relatively lower in May and October;among the annual changes,Tem 2015?2017>2016,Sal 2015>2017>2016,p H?TN 2016>2015>2017,CODMn?Chla2016>2017>2015,DIN?PO43--P?TP?TPHs 2017>2016>2015,DO?SS 2015>2016>2017.From the level of pollution,the content of inorganic nitrogen in most stations was more than three types of water,and the other environmental factors were first and second class quality.In the survey of 9 voyages in three years,3 species and 40 species of phytoplankton were checked.Among them,diatoms accounted for 35 species(genera),1 species of cyanobacteria,and 4 species of dinoflagellates.The average number of phytoplankton was 3.72×104cells/m3,of which diatom dominanted,and the alga also accounts for a certain proportion,and the other algae are less.The main dominant species were Coscinodiscus oculusiridis,Coscinodiscus radiatus,Skeletonema costatum,Noctiluca scintillans.The Shannon-wiener diversity index,Pielou evenness index and species richness index of phytoplankton in three years and nine voyages in 2016 were higher than those in 2015 and 2017.The results of CCA sequencing analysis showed that the key environmental factors affecting the distribution of phytoplankton were Tem?Sal?TP?PO43--P?DIN?TN and Chla.In the survey of 9 voyages in three years,23 species of zooplankton were identifiedbelonging to 7 main categories,including copepods and planktonic larvae.The average number of zooplankton was 68.50/m3,and the average number of zooplankton in 2015 years and in 2017 was higher than that in 2016.Although strong arrows the was the only hairy jaw species,but accounting for 39.92% of the total number,up to the absolute dominant species in each station.The main dominant species of zooplankton were Sagitta crassa ? Calanus sinicus? Parcaclanus parvus ?Acartia clausi.Floating survey showed that the number of zooplankton species changed little in three years,but the Shannon-wiener diversity index,Pielou evenness index and species richness index were higher in 2017 than those in 2015 and2016.The results of CCA sequencing showed that the key environmental factors affecting the distribution of zooplankton were Tem?Sal?TP?DO and Chla.