First catalogue of benthic marine macroalgae from glacier-influenced environments of the Beagle Channel, deposited in the new Sub-Antarctic Cryptogamic Herbarium (SCH) of the University of Magallanes

Abstract

The environmental characteristics and geomorphological landscape in the sub-Antarctic Magellanic ecoregion underpin a biological diversity that evolved adapting to the microhabitats produced by these heterogeneous ecological conditions. The high level of endemism found in these biological communities is nowadays protected thanks to the creation of the Cape Horn Biosphere Reserve (CHBR), a natural laboratory at the southern end of the sub-Antarctic Magellanic ecoregion. Studies produced in this region offer a valuable knowledge of its biological, ecological and cultural facets in a state still scarcely impacted by anthropogenic activities. The retreat of glaciers present along the channels and fjords of the CHBR due to global climate change impacts the marine benthic and macroalgae communities hosted in these water bodies. European expeditions in the 18th and 19th centuries pioneered the works which provided our current knowledge about this subantarctic marine flora. Nevertheless, there is still a gap of taxonomic information of macroalgae diversity in the CHBR. To solve this gap, with support of the Cape Horn Internationional Center (CHIC), we created the Sub-Antarctic Cryptogamic Herbarium (SCH) hosted at the Antarctic and Sub-Antarctic Marine Ecosystems Laboratory (LEMAS), University of Magallanes. In 2020, the New York Botanical Garden indexed the SCH in its Index Herbariorum. This indexation granted by this world-renowned institution places the SCH's biological collection as the world's southernmost cryptogamic repository. As such, the SCH's botanical collection is currently the only gateway to the subantarctic ecosystem's biological legacy. The catalogue below provides information about the ecological and morphological characteristics of macroalgae deposited in the SCH, with particular focus on those species present in the CHBR. We identified 54 species. Among them 23 belong to the Rhodophyta division (43%), 19 species to the Chlorophyta division (35%), and 12 species to the Ochrophyta division (22%). In the context of rapid global change, involving increasingly threatened taxa due to human impact, baseline studies and records deposited at the SCH will provide an essential tool for assessing patterns of change and defining conservation practices to protect the rich biodiversity of these sub-Antarctic ecosystems.