Effects of photon flux density and agricultural fertilizers on the development of <Emphasis Type="Italic">Sarcothalia crispata</Emphasis> tetraspores (Rhodophyta,Gigartinales) from the Strait of Magellan,Chile

Tetraspores of Sarcothalia crispata from San Juan Bay, Strait of Magellan, Chile, were cultivated under different combinations of photon flux densities and agricultural fertilizers in the laboratory. In the experiment, the S. crispata specimens were cultured in combinations of different photon flux densities (50, 100, 150 μmol photons m^-2 s^-1) and enriched seawater solutions (sodium nitrate + monocalcium phosphate, urea + monocalcium phosphate, ammonium nitrate + monocalcium phosphate), always adjusting the N and P concentrations to 10 and 3 mg L^-1, and in sea water as control. After 45 days, the tetrasporeling plants were found to be larger at photon flux densities of 50 and 100 μmol photons m^-2 s^-1 in the nutrient enrichment experiments; growth was greatest in the sea water enriched with ammonium nitrate and urea. An analysis of the combined effect of the photon flux density and nutrients revealed that the best combination for sporeling growth was the ammonium nitrate and urea solution at 50–100 μmol photons m^-2 s^-1.