Seven new macroalgas records for the Archipelago Diego Ramírez (56°31’S): the value of the new marine park as a sum of carbon and conservation of subantartic biodiversity

The marine ecoregions of Canals and Fjords of Southern Chile and Magellan Sub-Antarctic represent the extreme southern latitude limit for the distribution of numerous organism group. In southern Hemisphere, the most austral distribution site of kelps formation is placed at Diego Ramirez Archipelago, where Lessonia flavicans, L. searlesiana and Macrocystis pyrifera have been registered. Diego Ramirez Archipelago is located in the Drake Passage, 112 km southwest to Cape Horn. Regarding the available information for macroalgae, a total of 79 taxa has been reported, many of which show a sub-Antarctic and Antarctic affinity. Despite the biogeographic interest of the macroalgae from Diego Ramirez Archipelago, there have not been new cadasters to evaluate whether this archipelago could represent the northern boundary of the Antarctic species distribution and/or the southern boundary of Magellan species. The goal of this study is to update the cadaster of macroalgae from Diego Ramirez Archipelago, in order to find new taxa and contribute to the analysis of the biogeographic relationships of its phycoflora. From the sampling campaign at Gonzalo Island, 19 taxa of macroalgae were identified. In terms of richness by division, Chlorophyta was represented by 3 species (16%), Ochrophyta by 7 taxa (37%), and Rhodophyta by 9 taxa, representing the 47% of the identified flora. Thus, the present study combines our new registers together with the previous findings, providing an updated cadaster of macroalgae of the archipelago, suggesting a total of 86 taxa. Overall, it can be stated that all registered species of the archipelago show a sub-Antarctic affinity.