The maximum productivity observed for this species (12.0 g dry weighHm-2^d-1 ) occurred during continuous culture at 60% full sunlight under N-sufficient conditions. Doubling the light intensity lowered the productivity to 6.1 g dry weighHm-2^d-1. The chemical composition of N — sufficient cells (as an average percentage of total cell dry weight) was 64.2% protein, 12.6% carbohydrate, and 23.1% lipid. After 7 days of growth under N-deficient conditions, the composition was 26.8% protein, 59.7% carbohydrate, and 13.7% lipid. Therefore, this alga accumulates carbohydrates rather than lipids in response to nutrient deficiency, limiting its usefulness as a lipid production strain.

M. salina:

This alga reportedly contained high levels of lipids when grown under N-deficient conditions. The highest productivity (13.9 g dry weighHm-2^d-1) was observed under N-sufficient conditions at a light intensity of 50% full sunlight, although detailed experiments with regards to the effects of light intensity on productivity were not conducted. There was little difference in the lipid

3Reporting of productivities in g dry weight-m"2 — d"1 derives from the goal of mass culturing the algae in shallow open ponds. The objective would be to maximize biomass produced per area of pond. However, it is often difficult to compare results between experiments when the data are reported in this manner, as factors such as culture depth and vessel design would significantly affect productivity of the cultures.

content of cells grown under N-sufficient and N-deficient conditions (20.7% and 22.1%, respectively).

T. sueica:

The highest productivity observed for this strain was 19.1 g dry weight^m-2^d-1, which occurred in N-sufficient batch cultures grown under a light intensity of 60% full sunlight. N deficiency resulted in a large increase in carbohydrate content (from a mean value of 10.7% to a mean value of 47.1%). On the other hand, protein content was reduced substantially (from 67.6% to 28.3%), and the lipid content decreased from 23.1% to 14.6% in response to N deficiency.

Isochrysis sp.(Tahitian strain T-ISO):

This strain is commonly used as a feed organism in aquaculture production systems. A productivity of 11.5 g dry weight^m-2^d-1 was typical for batch cultures of this species, which was approximately 33% higher than the value recorded during semi-continuous growth (dilution of 0.15 L/d). Productivity was lowered during N-deficient growth to 5.5-7.6 g dry weight^m-2^d-1. This strain accumulated carbohydrate in response to N deficiency (from a mean value of 23.1% to 56.9%). Lipid content also increased slightly (from 28.5% to 33.4%), whereas protein content was reduced from 44.9% to 27.3%. The higher lipid content of N-deficient cells did not translate to higher lipid productivities, however, because of the lower overall productivity of the stressed cultures.

B. braunii:

Some very limited experiments were conducted with this species, which is known to accumulate hydrocarbons. A culture grown under a light intensity of 60% full sunlight had a productivity of only 3.4 g dry weight^m-2^d-1. The lipid content of these cells was 29% of the cellular dry weight; the N status of the cells was not reported, but it is assumed that the cells were grown under N-sufficient conditions.