St. Maarten Private Eye

The Simpson Bay Lagoon and its Ecological Value
Love the Lagoon, Environmental Protection in the Caribbean

By Rueben J Thompson - EPIC

The Simpson Bay Lagoon is situated in the south-western part of Sint Maarten and consists of a large surface of brackish water (mixture of fresh and saltwater). There are two little islands in the Lagoon, Little Key is the smallest island and is situated on the Dutch side and Great Key is on the French side.

The Lagoon has always served as a nursery for shrimp, lobster, conch and many species of juvenile reef and deep seafish. Grunts, groupers and other commercially valuable fish are dependent on the mangroves in the Simpson Bay Lagoon for breeding (spawning) and their early growth.

Many species of migratory as well as resident birds are dependent on the Lagoon for food and shelter. Several species of birds are in fact known to breed in the Lagoon, these species include: Yellow-crowned Night Heron (Nyctanassa violacea), Snowy Egret (Egretta thula), Mangrove Cuckoo (Coccyzus minor), Green Heron (Butorides striatus) and Wilson’s Plover (Charadrius wilsonia).

The Lagoon is an area where large seagrass beds occur. In the shallow areas of slow flowing currents these seagrass beds reduce the water’s velocity to almost nothing and act as huge natural filters removing particles from the water and depositing them as fine sediment. Seagrasses experience rapid growth in lagoons due to the relatively shallow waters which allow for ample sunlight to reach the beds and minimal currents which prevent shearing of seagrass blades. This rapid growth makes seagrass beds highly productive and suitable as feeding and nursery grounds. These ecosystems therefore attract a great diversity of wildlife, such as the great barracuda, stingrays, marine turtles, sea stars, sea cucumbers, sea urchins and the queen conch. It has even been reported that the Simpson Bay Lagoon was once home to the West Indian Manatee.

Although much of the Lagoon’s surrounding mangroves have been cleared, parts of its shoreline still host a significant amount of mangroves. Mangrove ecosystems have significant ecological, environmental and socio-economic functions and values. Mangrove communities usually occur in sheltered shores and in areas where sediment is gradually trapped forming mud banks. In short, the functions of mangroves include:
• Soil formation by trapping debris;
• Filtering land run-off and trapping terrestrial organic matter;
• Maintenance of coastal water quality;
• Shoreline protection
• Nursery areas and feeding grounds for juvenile reef and pelagic (deep sea) fish;
• Important habitat and feeding grounds for a range of other marine animals.

Four species of mangroves can be found on the shorelines of the Simpson Bay Lagoon: Red Mangrove (Rhizophora mangle), Black Mangrove (Avicennia germinans), White Mangrove (Laguncularia racemosa) and Button Wood (Conocarpus erecta). Red mangrove is easily recognized by its distinctive arching roots. Black mangrove, which often grows more inland, has root projections called pneumatophores, these snorkel like roots help to supply the plant with air in submerged soils. White mangroves often grow even further inland with no outstanding root structures. Button Wood grows in the higher laying areas behind the mangrove stands surrounding the lagoon. Compared to the rest of the Simpson Bay Lagoon, the Mullet Bay Pond area and parts of the French side of the lagoon house a fairly high density of Mangroves.

EPIC is often approached by people who wonder if the Lagoon is still worth saving. The answer is simple: Yes! The Simpson Bay Lagoon is still a very important Habitat. Now that you have read about the ecological importance of the Simpson Bay Lagoon. Make sure you read the next Lagoon Log for information on the different Environmental threats the Lagoon faces.

Rueben J. Thompson
Project Manager
Love the Lagoon
Environmental Protection in the Caribbean (EPIC)

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