Dynamic Characteristics Of Biotic Factors In Emerged Plant-specific Aquatic Microhabitats And The Influences On The Development Of Amphibians

As the dynamic process characteristics on the micro-scale can well reflect the total variability of the habitat on the larger scales,the characteristics and changes of the micro-habitat under different environmental conditions have gradually become the focus of researchers.Hydrophytes are often used in ecological restoration projects to improve water quality conditions.However,the dynamic characteristics of habitat factors of large-scale aquatic plants are not clear at the micro-scale,and the impact of the constructed microhabitats on species conservation remains to be studied.As the most endangered animal group in the world,amphibians exhibit a series of physiological limitations related to microhabitats.It has been found that abiotic factors in aquatic habitats can affect the growth and development of amphibians,but the relationship between the dynamics of biological factors,especially microorganisms,and the development of amphibians is still unclear.Firstly,microcosmic simulation systems were constructed based on three emergent plants,Acorus calamus L.,Canna indica L.and Zizania latifolia(Griseb.)Stapf,.The dynamic characteristics of the factors in the microhabitat of emergent plants were determined through the continuous monitoring of the physical and chemical indexes of water quality and the continuous monitoring of aquatic plants,phytoplankton,zooplankton and microorganisms.Furthermore,using the Pelophylax nigromaculatus as the representative of the amphibian,changes in abiotic component and biological factors in the microcosm,as well as the physiology and development of tadpoles,were investigated simultaneously.And the influence of different emergent plant microhabitats on the early development of amphibians was explored,and the correlation between each factor and the development of amphibians was analyzed.Finally,mesoscopic experiments were carried out in agro-wet system to analyze the changes of water quality and main biological factors,and to evaluate the conservation effect of P.Nigromaculata tadpole.The main results are as follows:1.In the microcosm simulation system of different emergent plants,the dissolved oxygen and p H were stable,the physical and chemical indicators of water quality showed certain changes,and the total nitrogen finally met the Class I water standard.The presence of emergent plants affected the growth of phytoplankton,Zizania latifolia had an inhibitory effect on the density of phytoplankton,and Acorus calamus increased the diversity of phytoplankton and increase the species and quantity of zooplankton.The presence of emergent plants provided more abundant microorganisms in the habitat.Acorus calamus could make the constructed microhabitats show higher biological biodiversity.2.The microhabitats constructed by emergent plants had a certain positive effect on the growth of tadpoles,but different emergent plants had different effects on the survival,development and physiology of tadpoles.All indicators of tadpoles in the Acorus calamus group were the best.The growth rate of tadpoles in the Canna indica group was the slowest,and the death rate of tadpoles in the Zizania latifolia group was the highest.The microhabitat with good water quality and richer phytoplankton,zooplankton,and microorganisms was suitable for tadpoles to survive.Tadpoles reduced the density of Chlorophyta and Bacillariophyta through the food chain.At the same time,tadpoles changed the microbial community structure by reducing the abundance of Bacteroides and Cyanobacteria.3.A mesoscopic study on the paddy-wet system showed that Zizania Latifolia had negative effects on the survival and development of tadpoles.The monitoring results were consistent with those in the microcosmic system.The results showed that the early conservation of amphibian was not good in the microhabitat constructed by Zizania Latifolia,which suggested that the suitable plant type should be selected for ecological restoration.This paper determined the dynamic changes of phytoplankton and zooplankton and the characteristics of microbial diversity in the emergent plant microhabitats,and found the influence of microhabitat factors on the development of amphibians by studying the dynamic characteristics of biological factors in different emergent plant microhabitats and their effects on the growth and development of amphibians.The interaction between organisms of different trophic levels in microhabitats was preliminarily investigated.The results of this study provided basic data for amphibian protection and habitat construction.