Measuring and protecting Andalusian coastal carbon sinks

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When forests disappear it is easy to notice. Much less visible, and happening 4 times faster, is the loss of marine meadows which keep significant reserves of carbon out of the atmosphere. Saltmarshes, which were traditionally disregarded, are now recognised as provide important ecosystem services. LIFE Blue Natura is focusing on measuring and protecting these vital carbon sinks.

A critical feature of climate mitigation

Blue carbon, as this carbon is called, is found in mangroves, seagrasses (Posidonia) and salt marshes on coastlines throughout the world. It is part of the biosphere carbon sink formed by organisms that naturally sequester, or remove, carbon from the atmosphere.

While many coastal areas in the EU are protected by the 1992 Habitats Directive, habitats where seagrasses and salt marshes are found are some of the most threatened ecosystems on Earth. Around 67% of mangroves, 35% of tidal marshes, and 29% of seagrasses have been lost around the world in recent decades, according to the latest estimates.

The vital role blue carbon sinks play in mitigating climate change, combined with the ecological threats they face, are the basis for LIFE Blue Natura's activities in Andalusia, Spain, which encompass the Mediterranean and Atlantic coasts, including the Bay of Cadiz, the Strait of Gibraltar, and the Odiel Marshes.

An unknown scale

The Blue Natura project team, led by the Andalusian Regional Council of Environment and Planning, has made some initial estimates about the size of blue carbon deposits in the EU.  Overall these habitats extend to between 12 000 km2 and 50 000 km2 of seagrasses and 5 000 km2 of saltmarshes.

The project team presented some its results so far at the European Parliament in November 2018.

Fieldwork and mapping

Between 2016 and 2018 the team measured carbon stocks and fluxes in the designated areas. They also improved mapping of the areas and assessments of their dynamics or changes affecting them.

"We collected around 140 sediment cores of between 18 – 290cm long and 110 biomass samples from different settings," said Professor María Soledad Rodríguez Ramos from the Andalusian Regional Council. "These included tidal exposure, seagrass species, water depth, geomorphology and conservation status: healthy, degraded, or restored."

Extra information on the health of seagrasses came from the POSIMED-Andalucía (website in Spanish), a collaborative network of professional and volunteer scientists.

The team found that globally the Andalusian seagrasses currently stock 13.4 megatons of CO2 in their top 1m of sediment, and sequester around 14 384 tonnes of CO2 each year. 95.5% of this carbon sink is attributed to Posidonia meadows.

Communicating together with regional authorities

Blue Natura's work has support from a new regional climate law, approved by the Andalusian authorities in October 2018, to combat climate change.

The project is working closely with the Secretary for Climate Change, responsible for implementing this new law. The team will join a regional campaign designed to make stakeholders and the wider population aware of the changes. This will include joining meetings arranged by the regional government for the private sector on how to offset carbon emissions through conservation and restoration of these blue carbon habitats.

Blue Natura has also been running an education campaign to share its results, and in 2019 is planning to organise seminars and workshops for public servants and decision-makers, NGOs and enterprises, journalists, and researchers.

Possibilities in other regions

"We are making serious efforts to share our results and experiences with other regions by attending the most important forums on the subject, and organising dedicated meetings with partners running similar initiatives in other European countries like Italy or Greece," said María Soledad Rodríguez Ramos.

The project team is also developing tools that could be applied in other regions, especially in the Mediterranean, including a carbon credit certification standard and a guide on how to offset certification of blue carbon projects around seagrasses and salt marshes. Other regions could also apply the same methods used by the project to measure blue carbon stocks and fluxes.

Blue Natura's efforts add to the increasing estimates of blue carbon stocks worldwide. This data will help push for stronger conservation and restoration activities by quantifying in concrete terms the ecological and financial benefits of these habitats.

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