14-05-2025
- Science
- South China Morning Post
Hong Kong oyster reefs' decline and restoration charted in documentary
Think of oysters and most people picture them on a bed of ice at a seafood buffet. But apart from being a Sunday brunch delicacy, these shellfish are the ocean's unsung heroes.
In their natural habitat, oysters are ecological superstars that are capable of improving water quality and stabilising shorelines.
They are hard-working, too: a single oyster can, through its gills, filter 200 litres (52 gallons) of murky water a day, creating healthy environments for marine species.
Oyster reefs – underwater structures formed by large populations of oysters that attach to hard surfaces such as rocks – once stretched along about 1,000 kilometres (620 miles) of coastline in southern China's Pearl River Estuary area, including Hong Kong.
This documentary is not just about oysters, but the bigger picture of rebalancing our relationship with the ocean
Mike Sakas, City of Shells director and producer
But over the centuries, the reefs were decimated as a result of over-harvesting, reclamation projects and pollution. A thriving limestone industry also led to their demise.
Oyster shells are 91 per cent limestone, which is used in cement and fertiliser. Limestone fuelled construction and agriculture during the 19th and 20th centuries.
