Dr. Otaiza-O'Ryan, Ricardo

Several seaweed species are commercialized worldwide both due to high demand for food and feed and as a raw material for the extraction of phycocolloids such as agar, carrageenan, and alginates that are used broadly in the food, cosmetic, and pharmaceutical industries. Chile is the world’s leading marine seaweed biomass producer when it comes to the exploitation of natural kelp beds. This extraction pressure has persisted for decades and has resulted in a reduction in natural stocks along the benthic ecosystems of the Chilean coast. Over the last three decades, several strategies aimed at restoring seaweed stocks have been implemented (i.e., sexual and asexual reproduction, the use of spore-type propagules or fragments of thalli, and entire thallus transplants). Success rates have varied, but the biological feasibility of such strategies has been demonstrated for several species. However, technological improvements must be achieved to move from small-scale, pilot experiments to cost-effective restocking strategies that are easy to transfer to fisher communities and another end-user, scalable to marine field conditions, and socio-ecologically sustainable. Researchers in other geographic areas have explored similar pathways for developing kelp restocking strategies and have tackled the research gaps regarding its massification. This work summarizes the research activities carried out in recent decades in the search for sustainable strategies to restore algal stocks in Chile.

Gelidium lingulatum is a frequent species at low intertidal levels of wave-exposed, rocky shores in central Chile. It is harvested from natural stands by artisanal fishermen and sold as raw material for the extraction of the valuable phycocolloid agar.Mass cultivation of this species has not been developed. In this study, we describe a device that allows seeding fragments of G. lingulatum to be used to increase biomass or to repopulate areas damaged by natural or anthropogenic disasters. The device consists of a nylon rivet and a mesh-washer that is pushed in perforations drilled on the rocky shore, holding the seaweed fragments appressed to the substratum favoring secondary attachment. Seeding was done on three sites in each of three localities within the Biobío Region (southern Chile), considering also the type of substratum (rock, calcareous crusts, and barnacles). The transplant units were installed in (austral) winter, 2016, and evaluated in spring and summer 2017. Results showed that, except for human intervention, most seeded fragments grew successfully as new patches and growth rates of up to 1.2% day−1 were recorded. Some significant differences were detected among sites and among substrata, but these can be interpreted as differences in the environmental conditions at the small spatial scale where the patch was growing. This device is simple and inexpensive and our results show that it is effective in producing new patches of G. lingulatum, such that it can be easily applied in repopulation or restoration programs.