Production of growth-enhancing particles in a plastic-lined shrimp pond

Abstract

Suspended organic particles produced in an intensive shrimp pond with an earthen substratum can significantly enhance shrimp growth. However, the role of the substratum in eliciting this effect is unknown. It was hypothesized that clay particles, derived from the substratum, are important in transferring suspended organic particles to the pond bottom where they become available to shrimp. To test this hypothesis, it was determined if suspended particles, produced in a plastic-lined pond without an earthen substratum, can improve shrimp growth. Juvenile Penaeus vannamei were reared in 120-liter microcosm tanks at a density of 40 shrimp/m 2. A 2 × 2 factorial experiment was conducted in which triplicate tanks received flow-through water from either a 337-m 2, plastic-lined pond used for intensive shrimp culture or from a seawater well. In addition, shrimp were fed either a commercial diet ad libitum or were unfed. After 14 days, there was a highly significant water source effect on shrimp growth ( P < 0.001). Growth rates of shrimp in pond water + feed (1.20 g/wk) were 62% greater than growth rates of shrimp in well water + feed (0.74 g/wk). Unfed shrimp in pond water grew 0.23 g/wk, whereas unfed shrimp in well water lost weight (−0.045 g/wk). These results indicate that algal-clay flocculation is not an important mechanism in eliciting the growth-enhancing effect of shrimp pond water and that particles suspended in pond water may not need to interact with the substratum in order to contribute to shrimp growth.