For each size of microalgae or inert feed, a specific feeding regime for Artemia
has to be developed to ensure adequate feed levels. The feeding regime developed
in this study for the microalgae Chaetoceros sp. and the inert feed Nestum resulted
in fast growth and high survival rates. Mason (1963) determined the growth
response of Artemia to various feeding regimes with Dunaliella tertiolecta. He
demonstrated that the amount of feed available per animal is the most important
variable affecting the growth of Artemia. In my experiments, the feeding regime
using Nestum gave similar results in growth, survival rate, and biomass production
to that using Chaetoceros. However, the time needed for the daily cleaning of the
culture systems of unconsumed feed was significantly higher with Nestum than with
the microalgae.
The survival rate after 11 days of culture obtained in this study (with Nestum
72%, with enriched Nestum 79%) was lower than data reported by Vanhaecke and
Sorgeloos (1989). They obtained a survival rate of 94% for Artemia from the San
Francisco Bay reared for 9 days at 25°C using Dunaliella tertiolecta as feed. For the
survival rate of Artemia fed for 11 days with enriched and unenriched Nestum, no
statistically significant differences could be determined. The wide variation of the
Artemia population estimates, because of many extremes and outliers despite a
standardized methodology of sampling and counting, made it impossible to determine
differences, if they exist at all.