The increase of nutrient availability allows the microalgae to have a biochemical
composition that is more similar to the nutritional requirements of Artemiu. There was a
strong correlation between the protein content of the microalgae and the survival, growth
and reproduction of Artemiu as maximum values for all parameters were obtained with
cultures containing maximum protein per cell (94.3 pg). Similar results have been
obtained when Artemiu were fed Spirulinu, as a high protein concentration (58%)
produced better growth and survival (Johnson, 1980). Despite the good correlation
obtained between growth and protein content of the algal food, the relationship
protein/carbohydrate/lipid in the diet cannot be discarded as a factor controlling the
development of Artemiu, since lipids as well as proteins are the main nutrients required
during the early developmental stages of Artemiu, whereas carbohydrate together with
protein are more important for juveniles and adults (D’ Agostino, 1980). Therefore the
relative proportion of these three components should be considered for the obtainment of
optimal growth. In the case of T. suecica, maximal protein content coincided with
maximal cellular caloric value, 3.69 X lop6 J per cell, both obtained with 8 mg atom N
1-l (Fabregas et al., 1995). The lower growth obtained with algae cultured with 16 mg
atom N 1-l may be the result of lower cellular protein content and caloric value,
although the intracellular accumulation by the microalgae of any micro-nutrient at a
toxic level with this high nutrient concentration cannot be discarded.