Influence of sediments of varying grain size composition on growth, survival and burrowing activity of the Ball Sea cucumber, <i>Phyllophorus proteus</i> (Bell,1884) juveniles

Abstract

Phyllophorus proteus is a high-value sea cucumber species in Philippines but is also one of the most exploited. Hatchery-produced juveniles are used for stock enhancement as a means of restoring depleted population however biology of <i>P. proteus</i> have not yet been studied on. Burrowing incidence of ball sea cucumber <i>P. proteus</i> (Echinodermata: Holothuroidea) juveniles (4-5 length x ≤1mm width), growth, survival and their associated daily behaviour were compared in 3 different substrate collected from Sagay, Negros Occ. (A-mostly coarse), Panobolon, Guimaras (B-intermediate) and Carles, Iloilo (C-mostly fine). This was to establish the most suitable type of substrate to use in the culture system for this high-value sea cucumber. The highest incidence of burrowing was observed in sediment profile C but the difference in the mean number of burrowing individuals between treatments was statistically insignificant (p>0.05). After 4 weeks, growth of <i>P. proteus</i> juveniles was significantly higher (p<0.05) when reared on profile C (growth rate: 0.79±.13mm %d-l) than either profile B (p=0.009) (0.34±0.14 mm %d-1) or profile A (p=0.030) (0.21±0.11mm %d-1). Survival is highest in profile B (S=100%), intermediate in profile C and lowest in profile A although the difference is insignificant (p>0.05) Very fine-fine-grained sediments is the most preferred by ball sea cucumber juveniles while coarse sand seems to be unsuitable.