While coral reefs ring a bell in most people’s mind, oyster and shellfish reefs are probably less known and even less understood. Hong Kong was home to shellfish reefs that have rapidly declined over the last 150 years changing the marine ecology of its waters. The Shellfish Reefs at Risk Report (2009) indicates that with 85% global loss, shellfish reefs are the most endangered marine habitat on the planet.
And to put in context the ecosystem functions these reefs perform, they not just provide shelter for crabs and snails but also are a nursery habitat for juvenile fishes and provide a surface for other organisms to grow including baby oysters.
They also provide feeding ground for larger fish and are a rich nutrient source for seafloor animals. They help in denitrification by removing excess nutrients, clearer water results in seagrass recovery and reduces the resuspension of fine sediment improving water clarity. They reduce wave energy protecting shorelines and human developments.
However, to start with some basics, it is important to understand what exactly a shellfish reef is. Well, these are three-dimensional biogenic structures created by habitat building bivalves like oysters and mussels. These structures are formed through the continuing deposition of shell material which is in turn degraded at varying rates and these are keystone species of estuaries and bays.
Also, not all shellfish are habitat forming like for instance clams. Bivalve shellfish that basically build on each other to create 3D structures is what is important from an ecosystem perspective. Intertidal areas with large freshwater inputs from rivers tend to be muddy environments which have estuarine oysters, as seen in the western waters of Hong Kong.
The transitional waters (becoming more saline) have mixed shellfish and different types of oysters, for example those from the Ostrea genus that tend to be more abundant in deeper waters and have been around since the time of the dinosaurs. They are more ancient than mangroves and seagrasses.
Hong Kong Oyster Reefs Exhibit in Pak Nai
The Hong Kong Government’s Environment and Conservation Fund has helped TNC establish the first permanent Hong Kong OysterReefs Exhibit in Pak Nai to help children and guests understand the environmental significance of oyster habitats. You can email to make a reservation along with your name and time slots (2:00 – 4:00 p.m. or 4:00 – 7:00 p.m.)
Read the story that first appeared in The Scared Groves Blog by The India Story Agency here: