Aquacult Int (2006) 14:587–594 DOI 10.1007/s10499-006-9057-y ORIGINAL PAPER
Effects of water exchange regimes on growth, survival and shell normality of the hatchery reared juvenile spotted babylon (Babylonia areolata Link 1807) in a recirculating seawater system S. Kritsanapuntu Æ N. Chaitanawisuti Æ W. Santhaweesuk Æ S. Y. Natsukari Received: 23 August 2005 / Accepted: 17 May 2006 / Published online: 14 July 2006 Ó Springer Science+Business Media B.V. 2006
Abstract Growth, survival and shell normality of hatchery reared juvenile Babylonia areolata were examined at four water exchange regimes of 0, 15, 30 and 60 day intervals in a recirculating seawater system over a 120 day experimental period. Higher body weight gains and shell length increments were observed in snails held at water exchange of 15 day intervals, especially when compared with those held at water exchange of 60 and 0 day intervals (P < 0.05). Water exchange affected the final survival of B. areolata. At the end of the experiment, final survival rates were 65.47 ± 0.66%, 87.48 ± 0.67%, 86.34 ± 0.92% and 78.50 ± 3.26%
for snails held in the water exchange treatments of 0, 15, 30, and 60 day intervals, respectively, and those of shell abnormality were 97.65 ± 1.04%, 93.09 ± 2.34%, 97.08 ± 1.18% and 96.71 ± 1.84%, respectively. The present study concluded that water exchange regimes of the recirculating system influenced growth, survival, shell normality and water quality of the recirculating culture system for this species. Keywords Babylonia areolata Æ Recirculating seawater system Æ Water exchange regime Æ Growth Æ Survival
S. Kritsanapuntu Faculty of Technology and Management, Prince of Songkla University (Surat Thani campus), Surat Thani, Thailand e-mail: firstname.lastname@example.org N. Chaitanawisuti (&) Æ W. Santhaweesuk Aquatic Resources Research institute, Chulalongkorn University, Pathumwan, Bangkok, Thailand e-mail: email@example.com S. Y. Natsukari Faculty of Fisheries, Nagasaki University, Nagasaki, Japan
Aquacult Int (2006) 14:587–594
Introduction From an aquaculture point of view, the spotted babylon, B. areolata, had many biological attributes, production, and market characteristics necessary for a profitable aquaculture venture, and it was considered a promising new candidate of aquaculture species for the land-based aquaculture industry in Thailand. Growing public demand and expanding markets for spotted babylon for a healthy, tasty, and affordable food is stimulating the ‘‘boom’’ in this industry. A catastrophic decline in wild spotted babylon populations as a result of overharvesting promoted the culture of farms—spotted babylon grown in indoor systems (Chaitanawisuti et al. 2002a, b). Although large-scale rearing of B. areolata in Thailand was technically feasible using flow-through and static seawater systems in concrete/canvass ponds, the disadvantages of these systems were: they generally require large quantities of water; location of production systems must be near the sea; stock was vulnerable to external water supply and quality problems; growth rate was significantly influenced by water flow (Chaitanawisuti and Kritsanapuntu 1999). Recirculating systems were mechanically sophisticated and biologically complex and had been used for growing fish and shellfish for more than three decades. Interest in recirculating systems is due to their perceived advantages, which include: greatly reduced land and water requirements; high degree of environmental control allowing productive-cycle growth at optimum rates; the feasibility of locating areas far from the sea; and a major issue of water conservation and reuse (Losordo et al. 1998; Masser et al. 1999; Lazur and Britt 1997). Research on recirculating systems may offer an alternative to pond aquaculture technology. It provides major leaps in the intensification and technology of the culture of spotted babylon. Much of this progress is necessary to maximize profits by increasing production, lowering costs, and conserving water. However, there is a lack of studies on growing of juvenile spotted babylon to marketable sizes in recirculating systems in Thailand. The goal of the present studies was to determine the effects of water exchange regimes on growth, survival and shell normality of hatchery reared juvenile spotted babylon, B. areolata, in a recirculating seawater system.
Materials and methods Experimental animals Juvenile spotted babylons used in growth and survival experiments were produced from a private hatchery. Individuals from the same cohort were sorted by size to prevent possible growth retardation of small spotted babylons when cultured with larger ones. Initial shell length and whole-body weight of the spotted babylon averaged 1.06 ± 0.16 cm and 0.33 ± 0.02 g, respectively, and did not differ significantly among treatments [P > 0.05, analysis of variance (ANOVA)]. Juveniles were raised in tanks as described below at densities of 300 individuals m–2 or 250 snails per tank. Experimental culture systems Each 50 l plastic culture tank was an independent recirculating system with air lift pump and a biological filter tank. The bottom area of the culture tank was 0.78 m2. The biological filter tank of 20 l capacity contained shell fragments and gravel as