PRELIMINARY STUDIES ON THE TOLERANCE TO TEMPERATURE AND SALINITY IN SAGITTA CRASSA

The tolerance to quickly-changed temperature and salinity,and gradually-changed temperature and salinity in Sagitta crassa were studied.The survival rate is 75% when the temperature changes from 15℃ to 1℃,but the survival rate is only 5% when the temperature changes from 15℃ to 30℃.The LTD(24)of sudden upper limit temperature is 27.2℃.When the temperature gradually changes from 20℃ to 25℃、30℃ and 35℃,the survival rate is 85%,10% and 0% respectively.When the temperature gradually changes from 20℃ to 15℃,10℃ and 5℃,the survival rate is 100%、95%、80% respectively.When the salinity suddenly changes from 31 to 20 and 40,the survival rate is 100%.With the increase of salinity changing range,the survival rate of Sagitta crassa decreases;The LTD(24)of sudden upper limit salinity is 45,and the lower limit is 13.3.The survival rate changes from 90% to 0 %,when the Salinity changes from 46 to 52.Also,the survival rate changes from 95% to 0 % when the salinity changes from 13 to 6.The LTD(24)of gradual upper limit salinity is 48.7 and the LTD(24)of gradual lower limit salinity is 9.3.The results suggest that Sagitta crassa may be a eurythermal,psychrophilic species and euryhaline near coastal regions.