Mariculture of Marine Plants: A Critical Pathway Approach

Mariculture of seaweeds for valuable products is on the edge of commercial development in the USA. Seaweed beds have been harvested for: food, industry, use in pharmaceuticals, cosmetics, fertilizers and livestock feed. These applications far outstrip the early, primary use of the seaweed extract agar in hospitals, as a base for microbiological culture media. As the seaweed beds have diminished, cultivation techniques for seaweeds have slowly developed to meet the world´s needs. Mariculture of native seaweeds presents formidible challenges. Research to date has taken numerous and diverse approaches from simple trial and error agronomy to controlled enclosure cultivation of selected strains. The new approach described here follows a Critical Pathway viewpoint including: Ecological Studies, Strain Selection, Physiological Studies and Cultivation Trials. Results from ecological studies provide clues for prudent strain selection and are further used to select the most important factors (e.g., light, carbon, temperature) for integration into experimental designs of physiological studies. Results from physiological experiments define tolerance ranges and presumed environmental optima for potentially limiting growth factors. These results are then tested in cultivation trials. The results provide data for production models for each strain or species considered for mariculture. Such a model is the basic tool for engineering design and mariculture development. Three California seaweeds have been the focus of this Pathway Approach: two species for biomedical purposes and one kelp for the herring-eggs-on-seaweed (Kazunoku kombu) fishery. It is concluded from results of these studies that the Critical Pathway is an effective approach to mariculture development. Moreover, many seaweeds from our own coastal waters can provide the raw material, now imported or unavailable, to meet the nation´s needs for seaweed products.