At the icy, wind-swept tip of South America lies Inútil Bay, a remote marine environment in the Tierra del Fuego archipelago that has long guarded its underwater secrets due to severe logistical and meteorological challenges. A multi-institutional team of researchers have successfully conducted the first comprehensive exploration of the intertidal and subtidal rocky ecosystems of Inútil Bay.

The expedition, supported by the Marine Program of Rewilding Chile, brought together specialists from CADIC-CONICET and the Universidad Nacional de Tierra del Fuego (Argentina) to conduct the first survey of benthic macroalgae in a region that had never been systematically studied before.

The findings from this survey, recently published in the Biodiversity Data Journal, provide a missing piece in the biogeographical puzzle of sub-Antarctic coastal environments. Benthic marine macroalgae act as important ecosystem engineers, modifying the physical structure of coastal habitats to create complex environments that support rich marine food webs and exceptionally high levels of biodiversity.

Beyond their role as local habitat providers, these extensive algal communities contribute significantly to global climate mitigation, while also serving as sensitive indicators of environmental health and human-induced disturbances.

Operating across six distinct sampling locations along both the northern and southern coasts of the Inutil bay, the research team deployed scientific diving techniques, including the use of 25-metre line transects and photo-quadrats to document all macroalgae species distributions.

This field methodology culminated in the documentation of 72 distinct macroalgal taxa, providing a major expansion of the known phytogeographic characterisation of the Magellanic region (Chile). The survey recorded 32 taxa in the variable intertidal zone and 58 taxa in the subtidal depths, comprising a diverse assortment of green, brown, and red algae.

While canopy-forming kelp species such as Macrocystis pyrifera and Lessonia flavicans dominated the underwater landscape alongside widespread species like Ptilonia magellanica, the researchers also catalogued rare and highly unusual specimens, for example, Microzonia velutina, a little brown macroalga.

All collected specimens are preserved at the Rewilding Chile Herbarium in Puerto Varas, ensuring that this dataset remains available to support future monitoring of these ecosystems, the detection of invasive species, and conservation planning in southern Patagonia.

At the same time, we are making progress on a collaborative alliance with the National Museum of Natural History of Chile, where we have already deposited an icefish larva (Champsocephalus esox) collected on a previous expedition and the Microzonia velutina.