Blue Carbon Ecosystems (BCEs)
Blue carbon ecosystems are coastal habitats that capture and store carbon while also supporting biodiversity. In Hong Kong, mangroves, seagrass beds, and tidal wetlands do more than absorb carbon; they stabilize shorelines, shelter marine life, and help connect land and sea.
Mangroves
By Frédéric Ducarme - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=107310307
Coastal forests that store carbon and provide shelter for a wide variety of organisms.
Found across Hong Kong's shorelines, mangroves are one of Hong Kong's most powerful blue carbon ecosystems. Their complex root systems trap sediment, slow down waves, and lock carbon into waterlogged soils that can persist for centuries. At the same time, they create shelter for juvenile fish, crabs, and other small animals. This makes them both a climate solution and a nursery for coastal wildlife.
Why it matters
Mangroves sit at the edge of land and sea, protecting coastlines against storms and erosion. When mangroves are destroyed, their stored carbon can be released and we lose a living coastal shield. Protecting mangroves means protecting biodiversity, climate resilience, and shoreline communities all at once.
Where to find them in Hong Kong
• Mai Po & Inner Deep Bay (largest and best-known)
• Ting Kok (near Yan Chau Tong)
• Tolo Harbour and other sheltered bays
Threats & management
Urban development, pollution, and climate-driven sea-level rise all threaten Hong Kong's mangroves.
Protected area status (e.g., Mai Po Ramsar Site) and restoration projects help slow their loss — but mangroves need space to move inland as sea levels rise, which requires careful coastal planning.
References
• AFCD. (n.d.). Hong Kong Mangrove Fauna. https://www.afcd.gov.hk/english/conservation/hkbiodiversity/speciesgroup/speciesgroup_mangrove.html.
• Wikramanayake, E., et al. (2020). A climate adaptation strategy for Mai Po Inner Deep Bay Ramsar site. PLOS ONE, 15(10), e0239945.
Seagrasses
Underwater meadows that hide in plain sight.
Seagrass beds are exactly what they sound like: meadows of flowering plants growing beneath the sea. They help to stabilize sediments, keep coastal waters clear, and provide nursery habitats for juvenile fish, crabs, and invertebrates. Below the surface, their roots and surrounding soils store carbon (often for centuries), making them one of the ocean's most efficient natural carbon sinks.
Why it matters
Seagrass beds are often overlooked because they are hidden beneath the water. But that's exactly why they need a voice. Yan Chau Tong Marine Park protects one of Hong Kong's most important seagrass meadows at Lai Chi Wo, showing that conservation isn't only about colourful reefs — it's also about the quiet, overlooked habitats that keep coastal food webs running.
Where to find them in Hong Kong
• Yan Chau Tong Marine Park (Lai Chi Wo — Site of Special Scientific Interest)
• Hoi Ha Wan Marine Park (seagrass patches among corals)
• Tung Ping Chau (smaller seagrass areas)
Threats & management
Seagrass beds are easily damaged by anchoring, trawling, dredging, and coastal construction. Because they grow so slowly, recovery takes years.
Marine park protections include no anchoring zones and no trawling, which are essential for management. The Lai Chi Wo seagrass bed's designation as a Site of Special Scientific Interest recognizes that some habitats are ecologically irreplaceable.
References
• AFCD. (n.d.). Seagrasses in Hong Kong: Conservation work. https://www.afcd.gov.hk/english/conservation/con_wet/con_wet_sea/con_wet_sea_con/con_wet_sea_con.html.
• AFCD. (n.d.). Yan Chau Tong Marine Park. https://www.afcd.gov.hk/english/country/cou_vis/cou_vis_mar/cou_vis_mar_des/cou_vis_mar_des_yan.html.
Mudflats & Tidal Wetlands
The quiet engine of the coastal food web
Mudflats may look empty from a distance, but they are among the most productive ecosystems on the planet. These vast, exposed flats at low tide are packed with invertebrates, such as worms, clams, snails, and small crustaceans. These feed thousands of migratory waterbirds during their long journeys. At high tide, the water returns, cycling nutrients between land and sea.
Why it matters
Mudflats and tidal wetlands are the link between land and ocean. They filter pollution, cycle nutrients, store carbon in their sediments, and support both birds and fisheries. When we drain or develop them, we lose not just a piece of shoreline, but we also lose the engine that drives the coastal food web.
Where to find them in Hong Kong
• Mai Po & Inner Deep Bay Ramsar Site (most extensive)
• Deep Bay (northwest Hong Kong)
• Smaller mudflats along Tolo Harbour and other estuaries
Threats & management
Mudflats have historically been seen as wasteland, places to fill in, drain out, or build on top of. But Mai Po proves otherwise. Protected as a Ramsar wetland of international importance, it shows that mudflats are not empty. They are feeding grounds, carbon sinks, and essential habitat for some of the world's most threatened bird species, including the Black-faced Spoonbill.
References
• Wikramanayake, E., et al. (2020). A climate adaptation strategy for Mai Po Inner Deep Bay Ramsar site. PLOS ONE, 15(10), e0239945.