Effect of biofilm density of grazing and growth rates of Haliotis fulgens postlarvae

摘要

Grazing rates of Haliotis fulgens postlarvae of different ages (7, 15, 30, 45 and 60 days), feeding on the cultured diatom Navicula incerta, were estimated in 10 mi sterile plastic dishes previously inoculated with different densities of the diatom(100-4,000 cells/mm~2). Postlarvae (3-7 per dish) were allowed to graze for two to three hours and video recordings were taken to estimate postlarval size and grazing rates by digital image analysis. Seawater was changed every other day and postlarvae were measured again after six to eight days to estimate growth. Grazing and growth rates of postlarvae older than 15 days increased linearly with biofilm density. The highest grazing rates for seven and 60 day-old abalone were 79 and 10,999 cells/postlarva/hour, respectively. The most important increase in grazing activity occurred between ages 45 and 60 days when postlarvae reached 1.5-2.0 mm and started the formation of the first respiratory pore. Implications for the management of production systems are discussed.