Growth and Survival Rate of Marphysa sanguinea (Polychaeta: Eunicidae) Juveniles by Tidal Water Drainage

Abstract

A study was conducted to evaluate the effect of different time exposures by tidal water drainage on growth and survival of Marphysa sanguinea, the abundance of copepods and relationship between copepod abundance and survival rate of M. sanguinea. Triplicate groups of worms (initial weight 0.19 ± 0.17g) were reared under five different time exposures (0hr, 1hr, 2hrs, 3hrs, 4hrs and 5hrs) for 120 days in a semi-recirculating system. Oyster shells (70%, 5 mm in diameter) and sand (30%, 2 mm in diameter) were used together as sediment. After the culture period, there were no significant differences in weight gain (WG) and specific growth rate (SGR) among juvenile M. sanguinea reared at 0hr, 1hr, 2hrs, 4hrs and 5hrs exposure to tidal water drainage. Survival rate of juvenile M. sanguinea reared at 3hrs and 4hrs was significantly higher than those of the control (0hr) (p>0.05). However, there were no significant differences among the survival rates of juvenile M. sanguinea reared at 0hr, 1hr, 2hrs and 5hrs and also among those of 1hr, 2hrs, 3hrs, 4hrs and 5hrs. The lowest copepod numbers were recorded at 5hr exposure and the lowest number was recorded at 0hr exposure of M. sanguinea juveniles to tidal water drainage. The copepod abundance reduced with increasing time exposure, however, at 5hrs time exposure, survival rate reduced. Therefore, it could be concluded that the optimum exposure time to tidal drainage for M. sanguinea could be between 3hrs to 4hrs for maximum survival.