tailieunhanh - Ảnh hưởng của một số yếu tố sinh thái lên quá trình phát triển phôi và cá bột cá chẽm mõm nhọn

The experiments were implemented during the spawning season from April to October 2007 in Nha Trang, Khanh Hoa under laboratory conditions. There were no significant differences of embryo development time when eggs were incubated at salinity of 20 ppt and 30 ppt. The salinity of 10 ppt was not suitable for embryo development. The surival rate of 3 - day larvae at 30 ppt group was higher than that of 20 ppt group. | 150 NGHIÊN CỨU KHOA HOC KY THUAT Anh HƯỞNG CUA MỘT SO YEU TO SINH THAI LEN QUA TRÌNH PHAT TRIEN phoi va ca BỘT CA CHEM MOM NHON Psammoperca waigiensis ECOLOGICAL FACTORS EFFECTING ON EMBRYO AND LARVAL DEVELOPMENT OF SAND BASS Psammoperca waigiensis Pham Quốc Hung Vu Thị Thanh Nga Nguyen Tường Anh Nguyen Đình Mao Khoa Nuôi Trong Thuy San Đai hoc Nha Trang Đai hoc Khoa hoc Tự nhien Đai hoc Quoc Gia TpHCM ABSTRACT The experiments were implemented during the spawning season from April to October 2007 in Nha Trang Khanh Hoa under laboratory conditions. There were no significant differences of embryo development time when eggs were incubated at salinity of 20 ppt and 30 ppt. The salinity of 10 ppt was not suitable for embryo development. The surival rate of 3 - day larvae at 30 ppt group was higher than that of 20 ppt group. No significant differences of embryo development time hatching rate and abnormal larvae rate were found when eggs were incubated at the density of 250 500 and 1000 eggs L. However the length of larvae and yolk sac size were different among the treatments. The greatest length and yolk sac size of larvae were observed at the incubating density of 1000 eggs L. On the other hand the smallest length and yolk sac size of larvae were identified at the treatment of 500 eggs L. The survial rate of 2-day larvae was not different among the three density treatments. Regarding to the exchange water treatments no significant differences of embryo development time hatching rate and abnormal larva rate were observed during the incubating period. There were however slightly differences of length and yolk sac size of larvae. The highest survival rate was found at the treatment of 50 water exchange daily. Under no aerator conditions the duration of embryogenesis was 16h10 the hatching rate was 42 and the abnormal larva rate was . However the survial of larvae just lasted until day 2. MỞĐẦU Qua trình phat triển phoi ơ ca xương được xac định từ khi trứng thu tinh .