Seeding of fragments of the agarophyte Gelidium lingulatum (Rhodophyta, Gelidiales) for the repopulation of lower levels of wave-exposed, intertidal rocky shores

Abstract

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.