St. Maarten boasts the largest inland lagoon in the Caribbean, and is one of the few islands containing expansive wetlands in the drier region of the eastern Caribbean, making it a critical habitat for many animal species. The island also has holds two of the significant permanent freshwater wetlands in the Dutch Caribbean.

These areas are especially important roosting, foraging and breeding grounds for many species of wetland birds including herons, egrets, stilts and coots. Depending on water depth, the ponds and lagoon shelter populations of fish, mollusks, and small invertebrates that provide a great source of food for the birds.

Wetlands are vital for human survival. They are among the world’s most productive environments, as cradles of biological diversity that provide the water and productivity upon which countless species of plants and animals depend for survival. They also provide countless benefits or “ecosystem services” ranging from biodiversity, to flood control, groundwater recharge, and climate change mitigation.

St. Maarten’s ponds and lagoon were once fringed with extensive mangrove forests, but the majority of these have now been destroyed by development and hurricanes. Small portions of mangroves are still present at Mullet Pond and around Little Bay Pond and Fresh Pond.

Simpson Bay Lagoon

Simpson Bay Lagoon is located on the southwest coast of St. Maarten, adjacent to the Princess Juliana International Airport. About half of the lagoon lies in the French part of the island. The bay has calm waters most of the year as it faces south and is therefore protected from the northeastern winds.

Simpson Bay Lagoon is a dominant feature of St. Maarten and is one of the largest lagoons in the Lesser Antilles, covering approximately one fifth of the island (1,250 ha). Its saline water is up to 6 meters/20 feet deep, and is relatively stable.

Simpson Bay used to have the most significant stand of mangroves and seagrass beds on St. Maarten, but coastal developments and hurricanes have removed much of the forest. Red mangrove (Rhizophora mangle) is most abundant along the water’s edge. Three species of seagrass have been recorded at Simpson Bay Lagoon:

  • Manatee grass (Syringodium filiforme),
  • Paddle grass (Halophila decipiens)
  • Turtle grass (Thalassia testudinum)

The seagrass and mangrove areas that remain provide a perfect habitat for a wealth of species, including the Upside Down Jellyfish (Cassiopeia frondosa) and gastropods such Queen Conch (Strombus gigas), Common Atlantic Bubble (Bulla striata) and King Venus (Chione paphia). They also are important feeding and nesting grounds for a variety of shorebirds such as herons, plovers and sandpipers.

The Simpson Bay Lagoon provides a large protected boat harbour around which a maritime industry has grown. The environmental, recreational, and commercial value of the Simpson Bay Lagoon drives a significant portion of St. Maarten’s economy. Most of St. Maarten’s fishermen are based in Simpson Bay. The bay also serves as a landing site for commercial fishing boats that operate offshore on the Saba Bank.

Much development has taken place at Simpson Bay, and the area is now full of hotels, restaurants, shops and casinos. As a result, Simpson Bay Lagoon is extremely polluted with heavy metals, sewage, oil, and other pollutants. The seagrasses in Simpson Bay Lagoon have all but disappeared as a result of pollution, anchoring and eutrophication.

The start of the construction of the Simpson Bay Lagoon Causeway in 2012 has meant the clearing of much of the lagoon’s mangrove forest. To compensate for this loss, thousands of juvenile mangroves have been replanted in the lagoon as well as at other locations on St. Maarten. EPIC’s project “Love the Lagoon” aims to protect and restore the Simpson Bay Lagoon. Education and outreach are used to encourage the community to be good environmental stewards, reduce pollution entering the lagoon, and protect the remaining habitat.

Mullet Pond

Mullet Bay Pond in 2018.

Mullet Pond (Ramsar Site no. 2270) is a semi-enclosed area of permanent shallow marine waters within the Simpson Bay Lagoon. The site holds some of the few intact seagrass beds in the wider lagoon as well as 70% of the mangrove forest remaining on St. Maarten.

The pond has been listed as a protected wetland of international importance under the Ramsar Treaty since October 2016. The Ramsar Convention is a global commitment to maintain the ecological character of global wetland areas, including in the wider Caribbean region.

The mangroves and seagrass beds act as a major nursery area and important habitat for juvenile fish species which develop in the lagoon before moving to local coral reef ecosystems including in the Man of War Shoal Marine Park. The nationally critically endangered buttonwood (Conocarpus erectus) is found on Mullet Pond. The site is also the last remaining habitat in the wider Simpson Bay area for Anolis pogus, a species endemic to the island, and the last intact foraging grounds in the lagoon for the globally endangered green turtle (ghelonia mydas).

The mangroves provide coastal protection during hurricanes and tropical storms, and help to cycle nutrients in the larger Simpson Bay area. As well as supporting the fish stocks which local fisheries depend on, the site is also used for eco-tourism activities such as kayaking tours.

The area is under continuing pressure from development, while other threats related to dredging, recreational and tourism activities, storms and flooding and invasive alien species including the red lionfish (Pterois volitans).

Great Salt Pond

From left to right: Great Bay, Philipsburg, Great Salt Pond

Great Salt Pond is located in south-central St. Maarten, north of Philipsburg. It is bordered on all sides by downtown Philipsburg and its suburbs. It is the largest permanent saline lagoon saltwater pond on the island; it covers an area of 2.25 km² (225 ha) and is up to 10 meters/33 feet deep.

It is unprotected, and its shorelines have been completely cleared of their native mangroves and grasses for urban development. This site is primarily used for landfill and land reclamation purposes.

Birdlife International has designated Great Salt Pond as an Important Bird Area for St. Maarten (IBA AN003). The area is especially significant as a stopover site for Laughing Gulls (Larus atricilla), with up to 5,800 gulls congregating prior to the breeding season. Great Salt Pond also provides a habitat for regionally threatened species: the White-cheeked Pintail (Anas bahamensis), Caribbean Coot (Fulica caribaea) and Ruddy Duck (Oxyura jamaicensis).

Fresh Pond

Fresh Pond is a permanent freshwater pond located in northern part of Philipsburg, just west of Great Salt Pond. It covers an area of 0.02 km² (2 ha) and is up to 3 meters/6 feet deep in the center.

The southern and western edges of the pond are fringed with red mangrove trees (Rhizophora mangle); the artificial islands at each end of the pond are also vegetated with mangroves. It is a public space and therefore does not receive any form of protection since the area around it is privately owned and completely developed.

Birdlife International designated Fresh Pond as an Important Bird Area for St. Maarten (IBA AN002). Due to its low salinity, Fresh Pond supports bird species that are less common in other parts of St. Maarten and the Lesser Antilles. The area has been identified as especially significant for its breeding population of endangered Caribbean Coot (Fulica caribaea). The artificial islands at each end of the pond provide popular nesting sites for waterbirds. The tall mangrove trees in the area provide a roosting habitat for egrets and herons.

Little Bay Pond

Little Bay Pond is located 1.5km (0.9mi) east of Philipsburg and covers an area of 0.02 km² (2 ha). It is a permanent freshwater pond, up to 3 meters/10 feet deep.

The depth of the overall pond attracts many swimming and diving birds, including waterfowl and seabirds. It is bordered with aquatic grasses and mangrove trees.

Birdlife International designated Little Bay Pond as an Important Bird Area for St. Maarten (IBA AN001). The pond is significant for its population of the endangered Caribbean Coot (Fulica caribaea). Up to 22 birds have been recorded at a time and some pairs breed. A number of other waterbird species breed at the site.