A group of scientists from the Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos Almirante Storni (Cimas) discovered that the alga Undaria, originally from Asia and introduced to the Argentine coasts, favors the development of marine invertebrate communities. Its large and complex structure creates new microhabitats that enhance biodiversity in intertidal ecosystems.
The finding is based on samples taken between 2021 and 2022 in the areas of Baliza San Matías and Punta Verde, within the San Matías Gulf. Researchers observed that the presence of Undaria significantly increases the quantity and variety of small species that inhabit among the rocks, many of which are essential for the diet of local fish and birds.
This brown algae is distinguished by its size —it can reach one meter in length— and by having a “holdfast” similar to a root, which allows it to attach to the substrate. On the Patagonian coast, it plays an unexpected role: reduces environmental stress during low tide periods, maintains moisture, and serves as shelter against extreme temperatures and predators.
The study also revealed that Undaria could be classified as a habitat-forming species, as its presence changes the physical structure of the coastal ecosystem and improves conditions for other species. Although its arrival was accidental, its ecological impact is being reevaluated by scientists.
A traveling alga that became a refuge
Undaria pinnatifida, commonly known as wakame, was first detected on the Argentine coast in 2014, near Puerto Madryn. Its arrival occurred through international vessels, possibly attached to the hulls of ships or as spores transported in ballast water.
Since then, it has expanded to various port locations —such as Mar del Plata, Comodoro Rivadavia, and San Antonio Oeste—, colonizing both port areas and natural environments. Its ability to adapt and reproduce has made it an established species along much of the coastline.
Although in other parts of the world Undaria is considered a problematic invader, in the San Matías Gulf its role is more complex. Researchers found that it helps to reduce coastal erosion, stabilizes the substrate, and favors the resilience of the intertidal ecosystem, especially in the face of climate change and tidal variability.
These environments —which are exposed during low tide and submerged with high tide— are critical areas for marine fauna. There, invertebrates that take refuge among the algae blades constitute the base of the food chain, supporting populations of fish and birds in the Bahía San Antonio Marine Protected Area.
The ecological benefits of Undaria
Beyond its exotic nature, Undaria offers notable environmental benefits. Its three-dimensional structure provides shade, moisture, and shelter for small organisms, which favors survival during abrupt temperature changes or sun exposure.
Additionally, it increases biological productivity in areas where bare or less complex surfaces previously predominated, allowing for greater nutrient retention and the creation of new ecological niches. This cascading effect benefits both coastal ecosystems and the fishery species that depend on them.
Globally, similar studies show that large algae like Undaria act as natural filters, capturing carbon and purifying water. In this sense, its presence on the Patagonian coast could help to mitigate the local effects of climate change and improve the quality of the marine habitat.
Although its introduction was unintentional, the case of Undaria demonstrates that even a foreign species can integrate and provide ecological balance when its impact is studied and managed appropriately. The key is to understand how its interactions transform ecosystems and what role they can play in the coastal conservation of the South Atlantic.
