Tree-line system: A sea bottom cultivation technology to improve the biomass production of edible seaweed Chondracanthus chamissoi (Gigartinales, Rhodophyta)

Chondracanthus chamissoi is a red seaweed of socioeconomic importance due to its use for direct human consumption; therefore, its cultivation is key to optimizing the production of this species and avoiding the exploitation of natural beds. In this study, a new background bottom culture technology, that is, the tree-line system, was evaluated. For this, a total of 18 tree-line systems were installed; the systems contained two types of substrates, which were inoculated with fragments of C. chamissoi: Halyard (H40 = 40 g m⁻¹); Raffia40 (R40 = 40 g m⁻¹); and Rafia80 (R80 = 80 g m⁻¹). Biomass production was recorded under three different harvest frequencies (30, 60, and 90 days). In addition, the epiphyte load found in the cultures was quantified. The results showed that both the frequency of harvesting and the type of substrate affect the amount of biomass produced. Monthly harvest did not favor biomass accumulation and, on the contrary, increased the epiphyte load. On the other hand, the treatment that was harvested only at 90 days obtained the highest biomass for substrates R40 and R80 with 916.02 ± 171.93 and 1017.84 ± 122.68 g m⁻¹, respectively, and with a low epiphytic load. These results are unprecedented and represent a substantial increase in the biomass production of this species, considerably higher than the results obtained in previous studies from different regions using vegetative propagation. With these results, a potential final biomass production of an entire tree-line system greater than 18 kg using a bottom sea area of 4 m² could be harvested after 90 days of cultivation.