D.R. Martinez-Ponce, R. Searcy-Bernal
Abstract:
This article describes attempts to estimate grazing rates of haliotid postlarvae. Two similar experiments with Haliotis rufescens postlarvae of different ages (2-30 days) were conducted. Postlarvae were placed into 10-mL containers previously inoculated with the benthic diatom Navicula incerta. Two hours later, video recordings at different magnifications on an inverted microscope were performed. Images were analyzed digitally to estimate grazed areas and diatom density, which were combined to calculate grazing rates. Individual grazing rates ranged from 20 to 724 cells/hour during the first month of postlarval life. Grazing activity was minimal during the first week but increased abruptly after the second or third week after a shell length of 0.47 mm was attained. The potential application of the quantitative assessment of grazing rates for optimizing abalone postlarval culture is discussed.
(Univ Autonoma Baja California, Inst Invest Oceanol, Apartado Postal 453, Ensenada 22860, Baja California, Mexico)