Effect of Biofloc Feeding on Growth and Survival Rate of Marphysa sanguinea (Polychaeta: Eunicidae) Juveniles

Abstract

Effect of biofloc feeding on growth and survival rate of Marphysa sanguinea (Polychaeta: Eunicidae) juveniles

War War Phoo

Department of Fisheries Biology, The Graduate School Pukyong National University

Abstract

The rockworm Marphysa sanguinea (Montagu, 1815) (Polychaeta: Eunicidae), one of the economically valuable species, has been increasing in demand for fishing bait as well as living food resource for fin fish and shrimp. Rockworm farms have recently started developing in order to understand and promote to complete the artificial seed production techniques. The aim of this study was to demonstrate the suitability of biofloc feeding of M. sanguinea juveniles. Two experiments were conducted for three months in biofloc feeding using M. sanguinea juveniles at Fisheries Science and Technology Center (FSTC), Pukyong National University. The first experiment of biofloc feeding was carried out with five feeding rates (3%, 6%, 9%, 12% and 15% of total body weight) with four replicates. Biofloc was fed everyday with shrimp feed powder 50% of crude protein (DongA One Corporation) and glucose in 1.55 of C/N ratio. The stocking density was 300 inds/bottle of 20 L capacity, in total 20 bottles were used with a mean initial weight of 0.057 ± 0.009 g of each worm. Worms were fed at the rate of 3% of body weight at the beginning. After 3 months of rearing, worms showed mean final weight of 0.084 ± 0.02 g, specific growth rate of 0.21 and the survival rate of 81.9 % in 15% feeding rate. However, 100% survival rate was found in 9% feeding rate with mean final weight (0.046 g) and specific growth rate (0.052) were lower than those of the initial weight. This result showed that out of five different feeding rates, 15% feeding rate was found with high growth rate and 3% and 9% feeding rates with high survival rates. The second experiment was conducted on the effects of stocking density on the growth and the survival rate of M sanguinea in 16 bottles; one bottle of 20 L capacity. The experiment was conducted in a feed supply system of 16 bottles connected to a 400 L of acrylic tank mixed with biofloc fed shrimp feed powder and glucose. Juvenile worms (average weight 0.179 ± 0.017 g) were stocked into 16 bottles with different densities (100, 200, 400, 800 inds/bottle) with four replicate bottles per treatment. Feeding rate were corresponding to 0.05 g, 0.07 g, 0.08 g and 0.16 g according to 3% of body weight in each treatment, respectively. Water exchanged at the rate of about 0.55, 1.11, 2.22 and 4.44% in every day. Specific growth rate (%/day) was during 12 weeks in all treatments and harvested biomass increased proportionally to stocking density (0.613, 0.019, 0.099 and 0.601%/day increasing stocking density, respectively). The results demonstrated that the growth and survival rate of M. sanguinea juvenile were significantly affected by different stocking densities (p ˂0.05).