Study On Age And Growth Of Freshwater Mussels And Microscopic Structure Of Shells In Poyang Lake

Poyang Lake is the first largest freshwater lake in China and with rich freshwater mussel species.But in recent decades,due to both the nature and the human activity disturbance,freshwater mussels resources were rapidly declined.Freshwater mussels are an important component of the benthic community in the freshwater ecosystem and which has important ecological functions.They move slowly with living areas relatively fixed and weak resistance to the environment change,which are one of the most vulnerable to groups.The author analyzed of the age growth,assessed the population structure and oberserved the microscopic structure of shell of mussels in Poyang Lake by using the thin section of shell for the age identifiction,so as to provide a scientific basis of freshwater mussels protection,utilization and management of resource in Poyang Lake.The main results were as follows:1.Measuring shell parameters of twenty species of freshwater mussel in Poyang Lake,analysising the relationships between the shell parameters.The relationships of shell length,height and width of twenty species of freshwater mussel is linear,and the relationship between shell length and shell weight is a power function.2.Thin section method was used to identify the age of twenty species of freshwater mussels,The results showed that the maximum age of the freshwater mussles for Lamprotula leai and Lampratula fbrosa,the maximum age for sixteen years;The smallest is Anodonta arcaeformis,the maximum age for two years.Through the relationship equation Y = In(X)+ b,the maximum age and the maximum theoretical L?.of 20 species mussels were infered.3.Shell rings and thin section were observed on two methods of identification for endangered species to identify the age and analysis the growth.Comparing two kinds of methods for(including five years)under the five years on age identification of mussel is consistent,while greater than five years differences.Growth analysis indicated that Solenaia carinatus growth faster before five years.4.Fourteen species mussel shells of prismatic layer thickness and the arrangement of the columnar structure were observed,the results showed that the prismatic layer of Schistodesmus lampreyanus is the thickest,Anodonta woodiana and Lepidodesma languilati are the thinnest.the nacreous layer "Bricks" structure,"pebble" shape,the arrangement and the size of them were listed and recorded.Results showed that Lamprotula rochechouarti,Lancelaria grayana?Unio douglasiae and Lamprotula caveata were not arranged neatly;Arconaia lanceolata,Lamprotula leai,Hyriopsis cumingii?Cristaria plicata?Cuneopsis pisciculus?Lepidodesma languilati and Schistodesmus lampreyanus were arranged neatly;only Solenaia oleivora and Cuneopsis celtiformis is messy,The biggest length of the brick is Hyriopsis cumingii,The smallest is Solenaia oleivora;The thickness of the bricks is not greater than 1 microns.