Uncovering the role of seagrass in climate change mitigation
Global environmental change is leading to a warming of the ocean as well as increased acidification. “The Mediterranean is a hotspot of climate change, with temperatures increasing significantly,” notes SHIFT2SOLVE project co-supervisor Jean-Pierre Gattuso from Sorbonne University in France. These rising temperatures are displacing and killing fish populations, stressing coral reefs and encouraging the growth of harmful algal blooms. Higher increased acidity levels meanwhile are a threat to species including sea urchins, sea snails and oysters, whose shells are dissolving at a faster rate. This damage will likely impact not only marine biodiversity, but also the lives of coastal communities and beyond.
Seagrass to measure oceanic climate impact
The SHIFT2SOLVE project sought to advance innovative methods of identifying and measuring these threats, as a key step towards developing effective mitigation strategies. The project was supported by the Marie Skłodowska-Curie Actions (MSCA) programme. To achieve its aims, the project focused on a species of seagrass endemic to the Mediterranean – Posidonia oceanica. A major objective was to assess the impact of ocean warming and acidification on this important marine plant, in order to assess its health status and see what actions should be taken. “Posidonia plays a key role in the Mediterranean,” explains project co-supervisor Núria Teixidó, from Sorbonne University and the Anton Dohrn Zoological Station in Italy. “It provides habitats for fishes, and protects the coastline by regulating currents and waves. It also stores carbon in its very long root systems.”
Aerial drones and AI modelling
Under the guidance of Gattuso and Teixidó, MSCA fellow Jordi Boda utilised cutting-edge analysis techniques to assess the health of these seagrass populations, in order to develop predictive modelling to estimate longer-term impacts of climate change. Aerial drones were used to characterise Posidonia meadows, and deep learning and AI tools applied to train drone photos to recognise underwater vegetation habitats. “The use of aerial drones was a powerful way to study coastal areas, allowing study of larger areas,” says Teixidó. Some of this fieldwork was carried out in the waters around the island of Ischia in the Bay of Naples. CO2 vents of volcanic origin provide a unique window into potential future acidification conditions. Lab-based work was also carried out at the Institut de la Mer de Villefranche, affiliated to Sorbonne University.
Effective conservation and restoration measures
A key finding was that Posidonia appeared to tolerate increased levels of ocean acidification, performing better than originally thought. Nonetheless, the team noted damage to the leaves, suggesting elevated stress levels. “This is something that we intend to study moving forward,” adds Teixidó. Another area of future research to build upon is aerial drone analysis. These techniques have great potential in delivering in-depth knowledge of seagrass communities and coastal ecosystems. Understanding the extent of Posidonia populations, and how much carbon they store, could help to drive environmental action. Achieving a better understanding of these marine plant communities is essential in order to put in place effective conservation and restoration measures. “In the case of Posidonia, the ability to store CO2 is spectacular,” says Gattuso. “Carbon can be stored in sediment up to six metres thick – this is CO2 that is removed from the atmosphere and can be sequestered for centuries to millennia.”
Keywords
SHIFT2SOLVE, seagrass, climate change, drone, oceans, Mediterranean, acidification