Study on water quality of a pond for keeping of scallop seedlings in Laizhou,Shandong Province
LI Xilei;YU Xiao;YANG Junli;CUI Longbo;College of Life Science,Yantai University;
In the course of harvest season,we selected scallop which was with good growth condition and larger individuals to cultivate indoors,and we stimulated them to spawn eggs at the same time. The spawning interval was 20 days at the two time. The larva of scallop can be transferred to seedling preservation pond for about 40 days after about 20 days of indoor cultivation. Scallop seedling preservation is a temporary culture stage before scallop is cultured into the sea,which can improve the adaptability of scallop and the survival rate of the seedling breeding. So the quality of water environment in seedling preservation pond would directly affect the quality and yield of scallop in that year. In general,the water temperature of seedling preservation pool should be stable above 13℃,the temperature difference of seedling pond should be less than 2℃,the salinity difference should be 5,the chemical oxygen demand should be less than 3 mg/L,and the p H should be stabilized in the range of 8. 0 to 8. 4. All the same,the death of scallop occurred in the process of scallop seedling preservation. In particular,the growth of the second batches of seedlings was slow and the survival rate was low. The death of scallop may be caused by poor water quality or its own weak constitution. In order to comprehend the environmental quality of scallop seedling culture,investigation were conducted on the pool of scallop seedlings in Laizhou from April to May of 2017. The results showed that the organic pollution assessment index is less than 1. The environment was in good condition and was basically uncontaminated. The nutritional state index was more than 1,and the phenomenon of eutrophication was frequent. And the comprehensive environmental quality evaluation index was less than 0. 75,and showed mild pollution. Chemical oxygen demand and inorganic nitrogen was the greatest contributors to all kinds of pollution. There were a total of 52 species of planktonic algae were identified in the survey,with the largest number of Bacillariophyta,such as Gyrosigma sp.,Thalassiothrix sp.,Nitzschia sp.,Cymbella sp.,Diploneis sp.,Pinnularia sp.etc. The dominant species was stable and diversified, the biodiversity was abundant, and the ecological structure was more stable. On the whole,the environmental quality of the pool was suitable for the cultivation of scallop seedlings. But the seedling preservation activities made the environment of the seedling preservation pool deteriorate,the water quality dropped,and the inappropriateness of the seedling preservation environment led to the death of scallop seedlings. So it is necessary to recognize the present situation of environmental quality,pay attention to the existing problems and take effective measures to improve it. The results of seedling preservation showed that the death rate of the two groups of seedlings appeared earlier and the mortality rate was higher,which was influenced by the health of scallop seedlings and the quality of environment.Therefore,we should select the fine varieties with good growth state and larger physique as parent of shellfish.
【CateGory Index】： X824
【CateGory Index】： X824