Field assessment of two methods for planting the agar-containing seaweed, Gracilaria, in Northern Chile

• Published in: Aquaculture Vol. 59; no. 1; pp. 31 - 43
• Main Authors: Pizarro, Alfonso, Barrales, Hugo
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.12.1986; Elsevier Science
• Subjects: Animal, plant and microbial ecology; Applied ecology; Aquaculture; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Gracilaria; Marine; ISE, Chile; South America; Growth; Atlantic Ocean; Algae; Biomass; Marine environment; America; South Atlantic; Bay; Chile; Culture; Thallophyta; Aquaculture
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/0044-8486(86)90076-1

Two simple methods for mass field cultivation of Gracilaria in Northern Chile were assessed. Thalli fragments were tied either to small rocks or to sand-filled polyethylene tubes to form 120-m 2 stands, on a shallow (3–5 m depth) sandy marine bottom with an underlying sandstone substratum. Short-term (6 months) thalli growth and resistance to wave action were evaluated on both stands, and the behaviour of these artificial beds was compared with that of a small undisturbed natural Gracilaria bed (ca. 3 ha) near the experimental area. A pilot artificial bed of 2500 m 2 was also established beside the experimental stands, for long-term assessment of the method using sand-filled tubes. Sand displacement and surfacing of the sandstone substratum due to moderate water turbulence caused a continual decline of the natural bed, but had no apparent effect on the artificial beds. Biomass increment in these plantations was 2600–2800% (fresh weight) in a 6-month period. Intense water turbulence at the end of this period had a significantly less destructive effect on the experimental and pilot beds planted with sand-filled tubes. Three years after the establishment of the pilot bed, natural recolonization had increased its area four-fold, in spite of intense and uncontrolled harvesting during the last year. This behaviour was attributed to the generation of a dense underground thalli system in this bed, due to the strong attachment provided by the sand-filled tubes. At this time (July 1985) underground biomass doubled the standing stock. Under the conditions tested in this study, the sand-filled tube method was the most feasible from a technological point of view.