Ảnh hưởng kết hợp giữa mật độ với chất đáy lên sinh trưởng và tỷ lệ sống của ấu trùng nghêu lụa (<i>Paphia undulata</i> Born, 1780) giai đoạn sống đáy tại Khánh Hòa

Abstract

    This study was carried out to determine the combined effects of different densities (2, 4, 6 and 8 individuals/cm²) and bottom substances (sand, sand-muddy, non-bottom substance) on the growth and survival rate of short-necked clam at the spat larval stage to seed in Nha Trang, Khanh Hoa. The experimented shortnecked clam (average length of 0.21 ± 0.012 mm) were conducted in the Styrofoam buckets and fed with algae of Nannochloropsis oculata, Chlorella sp., Isochrysis galbana in the period of 25 days. The results showed that there were significant combined effects of density with the bottom substance on the growth and survival rate of this clam (p<0.05). The absolute growth rate of clam was the highest (0.0832 ± 0.013 mm/day) at the density of 2 individuals/cm² combined with non-bottom substance treatment. The clams were cultured at a density of 4 individuals/cm² combined with the bottom substance of sand-muddy showed the highest survival rate (86.63 ± 2.06 %). In contrast, the treatments at the higher rearing density of 6 and 8 individuals/cm² combined with the bottom substance of sand showed the lowest growth rate and survival rate (p<0.05).

Key words: bottom substance, density, growth rate, short-necked clam, survival rate