Blue Carbon in Salt Marshes of Central Patagonia

What is Blue Carbon?

Blue carbon refers to the carbon stored in marine and coastal ecosystems such as salt marshes, mangroves, and seagrass meadows. These ecosystems capture and store large amounts of carbon in both plant biomass and sediments.

Specifically, salt marshes typically develop in estuarine and/or intertidal areas where slow water movement allows the accumulation of fine sediments, which are later colonized by halophytic vegetation. Spartina and Sarcocornia are among the most representative genera. The distribution of vegetation in salt marshes is influenced by factors such as sediment salinity, oxygen and sulfide levels, and flooding frequency.

Salt marshes are considered among the most valuable ecosystems due to the wide range of services they provide. These include opportunities for tourism, recreational activities, and education, as well as food provision, shelter, and breeding sites for many animal species. Additionally, salt marshes play a key role in coastal protection, water purification, and carbon sequestration—that is, capturing and storing carbon in soil and vegetation.

They are among the most productive environments on the planet, with annual productivity rates comparable to those of tropical forests. These ecosystems also play an important role in climate change mitigation, acting as carbon sinks that accumulate large amounts of organic carbon over centuries or even millennia—far longer than most terrestrial environments. However, when degraded, they can become sources of carbon emissions.

What are we studying?

We are assessing the carbon storage capacity in the sediments and vegetation of salt marshes within the Península Valdés Protected Area. We collect vegetation and sediment samples, analyze carbon content and stable isotopes, and estimate the proportion of local (autochthonous) versus external (allochthonous) carbon to better understand the processes of carbon capture and accumulation. We also determine biomass and vegetation cover.

Why is it important?

Despite their many benefits, salt marshes have suffered degradation due to human activity and climate change—two of the main global threats to these ecosystems. Their morphology is altered by both natural processes and anthropogenic pressures, and this transformation has accelerated significantly in recent decades, worsening their condition worldwide.

Conserving salt marshes is critical not only for biodiversity but also for climate action. These ecosystems can store more carbon per hectare than many forests, but when they are degraded, that carbon is released into the atmosphere. With global loss rates estimated between 25% and 50%, and less than 5% of original marshes remaining, understanding how they function is urgent.

Through this project, we are generating concrete data on how much carbon is stored in the salt marshes of Península Valdés and what factors influence that storage. The results will contribute to:

designing evidence-based conservation and restoration strategies,
strengthening public policies and protected area management,
and supporting international commitments to address climate change.

All information will be shared with local communities, decision-makers, regional scientific networks, and the Forum for the Conservation of the Patagonian Sea, of which ProyectoSub is a member.

Drone Mapping: A Key Tool

One of the innovations of this project is the use of aerial drone mapping. For the first time, we are conducting high-resolution spatial surveys in Patagonian salt marshes, producing detailed maps of vegetation structure and terrain geomorphology. This information supports ecological modeling, long-term monitoring, and conservation planning.

Aerial image of a salt marsh in Península Valdés

Aerial view of a salt marsh at Playa Fracasso, Península Valdés. The dominant vegetation belongs to the genus Sarcocornia, which is adapted to saline soils and periodic flooding conditions (image courtesy of Geoinformática, IPGP–CONICET).

What do we do at ProyectoSub?

At ProyectoSub, we promote applied research that generates useful information for the conservation of coastal ecosystems. In this project, our goal is to provide solid data on carbon storage in the salt marshes of Península Valdés, assessing how vegetation and local conditions influence the process.

Península Valdés is internationally recognized for its ecological value and is part of several conservation networks, including the UNESCO World Heritage List and the Western Hemisphere Shorebird Reserve Network. The information we generate will help identify which sites have the highest carbon storage potential, which plant species contribute most to this function, and what environmental conditions should be maintained or restored.

The results will be made available to protected area managers, environmental authorities, and other stakeholders involved in coastal ecosystem management and land-use planning in the region.