| The algal blooms and odor problems caused by different phytoplankton outbreaks in water sources in my country are serious,and the temporal and spatial distribution characteristics are unclear.It is urgent to establish a phytoplankton succession model.Morphological characteristics and their own photosynthetic characteristics.Studying the spatiotemporal distribution of phytoplankton from the perspective of morphological and photo synthetic characteristics can analyze the important driving factors of the spatiotemporal distribution of phytoplankton and provide a theoretical basis for algae control in water sources.In order to explore how the cell morphology and photosynthetic characteristics of phytoplankton affect their temporal and spatial distribution,this study selected 45 typical water source algal species based on their cell morphology characteristics and conducted laboratory experiments to systematically measure different morphological and photosynthetic parameters.The study analyzed the correlation between cell morphology and photosynthetic characteristics,and simulated different light environments to analyze the changes in morphology and photosynthetic characteristics of typical algal species.The study also summarized the temporal and spatial variation patterns of cell morphology and photo synthetic characteristics based on the phytoplankton monitoring data from the Yuqiao Reservoir,and clarified the mechanism of temporal and spatial distribution of phytoplankton populations based on cell morphology and photosynthetic characteristics.The main conclusions of this study are as follows:(1)There is a significant correlation between the morphological parameters of phytoplankton and the photo synthetic characteristic parameters.In the experiment,the cell projection area(CPA),which reflects the light-harvesting potential of phytoplankton cells during photosynthesis,was selected as the morphological characteristic parameter of phytoplankton.A correlation model was constructed between CPA and the regulatory performance energy dissipation quantum yield(Y(NPQ)),the initial slope of the EP fitting curve(α),and the maximum electron transfer rate(ETRmax).CPA showed a positive correlation with Y(NPQ),α,and ETRmax,with P values less than 0.001.The linear model of Y(NPQ)and CPA was more stable and representative of the photo synthetic characteristic parameters.(2)Analysis of changes in morphological characteristics and photo synthetic properties of phytoplankton under different light environments.Green algae can grow well in all light environments,and the growth of three cyanobacteria cultivated under red and white light is the best.Filamentous cyanobacteria Pseudanabaena limnetica 639 grows better under green light than the other two cyanobacteria.The Y(NPQ)variation trend of cyanobacteria and green algae is relatively similar under different light environments,decreasing at the beginning of cultivation,increasing and stabilizing in the middle and later stages.However,unlike green algae,the morphological changes of cyanobacteria under different light environments lead to differences in the final stable value of Y(NPQ),with a higher Y(NPQ)under green light and a lower Y(NPQ)under red light.Pseudanabaena limnetica 639 undergoes changes in the composition of light-harvesting pigments under different light environments,making its morphological parameters more significant.The filamentous cyanobacteria with phycocyanin have a better adaptation to changes in light environment.Under green light,cell length increases,width decreases,CPA increases,and Y(NPQ)rises.Under red light,cell length decreases,width increases,CPA decreases,and Y(NPQ)decreases.The filamentous cyanobacteria adapt to changes in light environments more significantly by changing CPA,and the morphological changes under different light environments help the filamentous cyanobacteria to periodically float up and sink in the bottom and surface layers of water bodies.(3)Photosynthetic characteristic and morphology parameters of phytoplankton affect the temporal and spatial distribution of phytoplankton in the Yuqiao Reservoir.A total of 63 genera from 7 phyla of phytoplankton were found in the Yuqiao Reservoir.The dominant species of phytoplankton in the reservoir showed significant seasonal changes.Diatoms were the absolute dominant species in the reservoir except in summer,and cyanobacteria were the most abundant in summer.Green algae and golden algae were dominant only during the transitional periods in spring and autumn.The most dominant species in the Yuqiao Reservoir in spring were Microcystis,Anabaena,Chrysophyta,and Aphanizomenon;in summer,they were Microcystis,Oscillatoria,Chrysophyta,and Aphanizomenon:in autumn,they were Microcystis,Anabaena,Cyclotella,and Aphanizomenon;and in winter,they were Microcystis,Cyclotella,Chlamydomonas,and Jaaginema.Filamentous cyanobacteria are widely distributed in water sources and are in a dominant population position.The diatoms with high CPA and high Y(NPQ)in spring are the dominant community in Yuqiao Reservoir,while the cyanobacteria with low CPA and low Y(NPQ)are dominant in summer.The seasonal distribution of CPA and Y(NPQ)in Yuqiao Reservoir is the same,showing a trend of decreasing gradually from winter to summer,and then increasing gradually from summer to winter.Together,they affect phytoplankton population succession.Phytoplankton with high Y(NPQ)are suitable for survival on the surface of water,while those with low Y(NPQ)have weak photoprotection ability and live in the bottom of water.The Y(NPQ)of phytoplankton affects the spatial distribution of morphology,and the spatial distribution of phytoplankton Y(NPQ)shows a trend of decreasing with increasing depth.The spatial and temporal distribution of phytoplankton is influenced by the morphological and photosynthetic characteristics of phytoplankton. |
