Organic Carbon Stocks in Earth's Most Remote Blue Carbon Ecosystems.

Area of Science:

• Marine ecology
• Carbon science
• Remote sensing

Background:

• Tropical coastal ecosystems are critical for blue carbon sequestration, storing substantial organic carbon (Corg) over centuries.
• Mapping these ecosystems via remote sensing faces challenges like cloud cover and inconsistent methodologies.
• High-resolution benthic habitat maps from the Global Reef Expedition provide a unique dataset for assessing remote blue carbon habitats.

Purpose of the Study:

• To systematically assess the extent of blue carbon habitats (mangrove forests, seagrass meadows, macroalgal habitats) in remote tropical marine ecosystems.
• To provide new map-based estimates of blue carbon storage in these ecosystems.
• To identify potential blue carbon hotspots and assess habitat fragmentation.

Main Methods:

• Utilized high-resolution benthic habitat maps from the Khaled bin Sultan Living Oceans Foundation's Global Reef Expedition (2005-2016).
• Mapped mangrove forests, seagrass meadows, and macroalgal habitats across 69 study areas (∼15,970 km²).
• Integrated map data with regional carbon stock data to estimate organic carbon storage.

Main Results:

• New map-based estimates quantify blue carbon habitats in 69 remote tropical study areas.
• These ecosystems store an average of 41.84 Tg Corg, with significant regional variation (4.69-176.95 Tg Corg).
• The Solomon Islands, Bahamas, and Colombia identified as potential blue carbon hotspots; French Polynesia shows high fragmentation.

Conclusions:

• Globally consistent mapping and new stock estimates address critical knowledge gaps for remote ecosystems, 82% of which were previously unassessed.
• Findings offer essential baseline data for effective management and conservation strategies for tropical blue carbon ecosystems.
• Highlights the importance of these ecosystems for climate change mitigation through long-term carbon sequestration.