INGESTION RATE AND FEEDING-BEHAVIOR OF THE PEPPERMINT SHRIMP LYSMATA-WURDEMANNI ON ARTEMIA-NAUPLII

A laboratory study was conducted to examine the effects of food level and water temperature on the ingestion rate in the larvae of the peppe rmint shrimp Lysmata wurdemanni, a popular aquarium species. Artemia n auplii were used as the food item. Number of newly hatched Artemia nau plii consumed by the larvae (from zoea II: to zoea VII, zoea I can met amorphose to zoea II without exogenous nutrition in about one day) was measured daily at four food concentrations (2, 5, 10 and 20 Artemia n auplii/ml) and mio temperature levels (25 C and 28 C). The experiment was conducted in 500-mL beakers with three replicates for each treatme nt. The results show that the shrimp consumed significantly more food at 28 C than at 25 C (P < 0.01). Ingestion rate increased with increas ing food concentration in all larval stages and with larval developmen t except for the lowest food level (2 Artemia nauplii/ml) where insuff icient food supply limited the ingestion rate to around 35 Artemia nau plii/larva per d after zoea IV stage. The larval development rate was significantly lower (P < 0.05) in the shrimp subjected to the two lowe st food concentrations (2 and 5 Artemia nauplii/ml) in the 500-mL beak ers. But in a separate experiment conducted in the 1,400-mL beakers, t he results were reversed: both survivorship and development rate were significantly lower at the two higher food levels (6 and 12 nauplii/ml ) than those at 3 nauplii/mL, lever. During molting period, ingestion rate decreased significantly, followed by a sharp rise to the normal r ate the following day.