ARTIFICIAL CULTURE OF MARINE SEA WEEDS IN RECIRCULATION AQUARIUM SYSTEMS

¹ Biological and Medical Sciences Division, U. S. Naval Radiological Defense Laboratory, San Francisco, California 94135

Ulva as either sporeling or transplant could be cultured for periods of three months in closed recirculating aquarium systems. Early development of Ulva lobata sporelings proceeded normally and rapidly under conditions imposed and compared to closely related species. i. e., Ulva pertusa and Ulva lactuca. A modified Haxo-Sweeney enrichment was used. substituting B vitamins and organic phosphate for soil extract. Continuous flow ultraviolet sterilization and microfiltration were provided. The pH was maintained automatically at 7.9 ± 0.3, using Tris buffer and gaseous CO₂. Improved fluorescent illumination for 13-15 hours favored culture of sporelings and summer transplants. Irradiance was confined to the spectrum lying between approximately 380-725 mµ. and amounted to 3.7 kilolux. From field observations, photoperiod appeared closely correlated to initiation of vegetative growth during early spring. Water temperature seemed to have a greater effect on the rapid maturation of gametes and zoospores.