──From May to November of 1 995,. P. chinensis were used experiments using excessive artifical di- ets as organic pollutants. Twenty about 8 , 10 or 1 2cm body length P. chinensis.. were put into the test pond and control pond. After 2～ 3 weeks , susceptibilities to pathogenic bacteria the number of haemocyte and lysozyme , SOD. PO activities were compared. The results were as follows. Susceptibilities to Vitrio para- haemolyticus , were 1～ 3 times that of the control pond shrimp (Table 1 ) , the haemocyte number of the test shrimps decreased about 50% , the SOD. PO and 1ysozyme activities of the test pond decreased a bout 22%, 50% and 28%～86% compared with those of the control pond (Table 2). Additionally it has been proved that in the test pond following the excessive artifical diets degreded , the DO content decreased , NH3-N increased markedly. So the conclusion could be drawn : organic pollution affects aquatic environment , decreases immune level , enhances susceptibilities to pathogen bacteria .
Acta Oceanologica Sinica
Penaeus chinenses, organic pollution , anti-disease ability . immune level