Abstract
Species of the genus Gracilaria are widely distributed around the world, and many are wild harvested and cultivated for phycocolloid production (agar) and human food. This study investigated the growth performance of three color strains of Gracilaria domingensis in an integrated organic system. The three chromatic variants (red, green, and brown) were cultured in a shrimp farm at two depths (surface and 20 cm). The highest relative growth rates were obtained in the first week of cultivation for all three strains studied. Although the growth rates and biomass were slightly higher at a depth of 20 cm, significant differences were not observed at different depths (p < 0.05). The growth of the three strains varied significantly over time (p < 0.001). The maximal growth values obtained were 11.25 ± 1.50% day−1 (red), 12.76 ± 3.96% day−1 (green), and 7.86 ± 1.75% day−1 (brown). The mean growth rates for the whole period were 4.63 ± 6.97, 3.38 ± 9.09, and 2.16 ± 6.61% day−1 for the red, green, and brown strains, respectively. The pigment content (chlorophyll a, phycocyanin, and phycoerythrin) of the three strains studied was higher at a depth of 20 cm, while the maximum electron transport rate (ETRmax) and photosynthetic efficiency were higher at the surface. The high growth rates obtained in this study demonstrate the great potential of this species for integrated organic farming. Moreover, the ecological success shown by the red strain suggests that this strain is the most suitable for integrated cultivation.
Highlights
Species of the genus Gracilaria are widely distributed around the world, and many are wild harvested and cultivated for phycocolloid production and human food
The high growth values achieved by the three strains in the first weeks of the experiment are in agreement with previous results with other Gracilaria species (Nelson et al 2001; Yang et al 2006; Samocha et al 2015)
The mean RGR of the three strains of G. domingensis obtained for the whole period (2–4% day-1) was higher than those found in other Gracilaria species tested in shrimp ponds in Brazil (Marinho-Soriano et al 2002, 2009; Oliveira et al 2012)
Summary
Species of the genus Gracilaria are widely distributed around the world, and many are wild harvested and cultivated for phycocolloid production (agar) and human food. The high growth rates obtained in this study demonstrate the great potential of this species for integrated organic farming. Several Gracilaria species have been cultivated on a large scale in many countries, which has been mainly attributed to high growth rates and easy vegetative propagation. Strain selection should be based on such important criteria as adaptability to a wide variety of environmental factors, high growth rates, nutrient removal efficiency, and economic potential (Neori et al 2004). Integrated multi-trophic aquaculture (IMTA) has been shown to be a very promising method for seaweed production This practice is based on the use of one species’ waste to provide food for another (Chopin et al 2008; Wu et al 2015). IMTA has the potential to contribute to a positive, sustainable image, and improved social acceptability (Barrington et al 2010)
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