The addition of Ulva reticulata as a feeding stimulant into artificial feed on the gonad condition of the collector sea urchin (Tripneustes gratilla Linnaeus 1758)

Dried Ulva reticulata proven acts as a feeding stimulant for the collector sea urchins (Tripneustes gratilla). This study aims were to determine the optimal dose of dried U. reticulata as a feeding stimulant into artificial feed and its effect on the gonad condition of the collector sea urchins, T. gratilla. Previously starved sea urchins (ca. 66 mm diameter, n=7) was held in 80- L aquarium volume with flow through seawater system (6.25 L/hour inlet and outlet). Sea urchins were fed one diets containing 0, 10, 20 or 30 persen of dried U. reticulata (designated Control, U-10, U-20 and U-30 respectively) ad libitum for 38 days. Each treatment was given 3 replications. Survival rate, feed consumption, and gonad condition (gonad index, biochemical composition of the gonad, gonad histology, and egg diameter) parameters were quantified and as compared to sea urchins fed a fresh macroalgae (Gracilaria lichenoides and Padina) and seagrass (Enhalus acaroides) mixture (MS). The results showed the addition of dried U. reticulata into artificial feed by 10 persen from feed weight (U-10) is the optimal dose recommended. Sea urchins treated U - 10 diet resulted in gonad index and egg diameter (5.02 persen and 82.66 µm each), are higher than the other diet treatments. Although this diet treatment not been able to homogenize the reproductive phase composition of T. gratilla.Keywords: Ulva reticulata, Feeding Stimulant, Tripneustes gratilla, Gonad Condition Jurnal Ilmu dan Teknologi Kelautan Tropis 6(1):63-79