Cultivation of Gracilaria in outdoor tanks and ponds

Abstract

This review deals with the major problems of unattached Gracilaria intensive cultivation in outdoor tanks and ponds. These problems are presented through the main variables affecting the Gracilaria annual yield and the updated solutions evolved. The physical variables include tank and pond structure, seawater characteristics such as velocity, agitation practice, exchange rate, and salinity, light characteristics such as quantity and quality, and temperature modelling. The chemical variables include nutrient composition and regime of application, and inorganic carbon supply with the pH changes involved. The biological variables include seaweed density, epiphyte competition, grazer damage, bacterial disintegration, integrated mariculture and strain selection. The experience gained in the Israeli research on Gracilaria cultivation is discussed in view of other Gracilaria and seaweed intensive cultivation research.

Abalone farming in South Africa: An overview with perspectives on kelp resources, abalone feed, potential for on-farm seaweed production and socio-economic importance

“…Some other abalone farms carry out experimental seaweed farming, building on the knowledge gained since the research on integrated seaweedabalone (initially Gracilaria gracilis and later species of Ulva) culture started in 1993 by the University of Port Elizabeth. Since then numerous studies show upon that seaweeds grow better in abalone effluents compared to natural seawater (Fourie, 1994;Friedlander and Levy, 1995;Smit, 1997;Hampson, 1998;Steyn, 2000;Robertson-Andersson, 2003;Njobeni, 2006). Seaweeds being used for on-farm cultivation come mainly from populations in sheltered waters (bays or harbours) where they grow naturally unattached.…”

Influence of depth on the growth of the seaweed <i>Gracilaria birdiae</i> (Rhodophyta) in a shrimp pond

“…Despite the experience obtained in different studies, the cultivation of Gracilaria in integrated systems is still difficult in theory and practice (Marinho-Soriano et al, 2002;Buschmann et al, 2008). Limitations in acclimation, nutrient absorption, photosynthesis and various abiotic factors leave gaps in our understanding of this group (Friedlander & Levy, 1995). This limited information prevents an effective understanding of these algae in eutrophicated environments and "in situ" studies are necessary to clarify the physiological response of the algae to environmental parameters.…”

Effects of increased CO2 levels on growth, photosynthesis, ammonium uptake and cell composition in the macroalga Hypnea spinella (Gigartinales, Rhodophyta)

“…The effect of these waste effluents (rich in C, N, and P) has been reported to enhance seaweed growth, and biofilters can thus reduce the overall environmental impact. In these cultivation systems operating under high algal densities, especially when nitrogen and phosphorus are available, the inorganic carbon sources could become limited (Bidwell et al 1985;Friedlander and Levy 1995); therefore, such highly productive units could be considered potential sinks for CO 2 . The longer-term response of photosynthesis and growth to CO 2 enrichment will depend on the availability of mineral nutrients and the way they are used by the plant because the higher growth rates will lead to an increased demand for nutrients, particularly inorganic nitrogen and phosphorus (Stitt and Krapp 1999;Xu et al 2010).…”