Bonaire National Marine Park - LAC - FAUNA

Lac, with its combination of mangrove forest, seagrass beds and the coral dam, which act as a border between the open ocean and Lac, is one of the most biodiverse wetlands in the Caribbean.
When you visit Lac, the diversity of birds, fish, and other life will attract your attention immediately. Each area of Lac -- the mangrove forest, the open water area and the coral dam -- forms a different habitat where specific organisms live. These organisms use the specific circumstances of the habitat to their advantage; most are perfectly adapted to the habitats in which they live.

Click on the links to find a short description of the three different areas and an introduction to the fauna you will find in each area.

The mangrove forest:
The mangrove stands are particularly important as nesting and roosting areas for birds. The entire mangrove forest is a protected bird sanctuary. The brown pelican (Pelecanus occidentalis), the great blue and great white heron (Ardea herodias), the frigate bird (Fregata magnicicensis) and the royal tern (Sterna maxima) are the most common species in this area, but most of the bird species present in Washington Slagbaai National Park can also be observed in the mangroves during the right times of day or seasons. Flamingos (Phoenicopterus ruber) often feed in the open shallows, the saltier parts of this system.

Most of the fish on Bonaire’s reefs spend at least some portion of their lives within these mangroves. While some studies show that fish will move to an alternate habitat if no mangrove area is available, this results in fewer fish, which are smaller in size. (Ref.: University of Exeter Marine Spatial Ecology Lab).

The similarity of the results of two research studies of Lac, conducted in 1992 and in 2000, (see Research and monitoring) supports the idea that the mangroves and seagrass beds are important nurseries for many reef fish species as well as various invertebrates. All these creatures find haven from predators and shelter from storms. All of them feed on and add to the rich soup of the submerged (detritus) food web. The mangroves provide a location where fish and invertebrate larvae, while in the floating planktonic stage, arrive on incoming currents for settlement.

Values: - not important; () doubtful; x minor importance; xx medium importance; xxx major importance (adapted from van der Velde et al. 1992)

Other creatures that attract attention immediately, when you are snorkeling or kayaking between the mangroves, are the upside-down jellyfish (Cassiopeia xamachana) and the flat mangrove oyster, the leaf oyster (Lopha folium).

The upside-down jellyfish is present throughout the whole mangrove system but are usually concentrated in shallow bays and inlets. Its fringe of stinging tentacles and grape-like oral arms faces up to absorb sunlight to nourish the symbiotic algae embedded in its tissues. The upside-down jellyfish are usually yellowish brown with white markings, but can appear in different color variations (brownish, greenish, purple, etc.).

The flat mangrove oysters make use of the mangrove roots to cling together and form a big siphon filter. These bivalves are often covered with debris and encrusted with a camouflage of sponges, algae, and tunicates.

Different species of insects and fruit bats transport pollen to fertilize the pale yellow, less than one-inch (red) mangrove flower. A single pencil-shaped green seedling up to eleven inches long develops from the fruit of this flower. These organisms are important for the survival of the mangrove forest in Lac.

The open water area:
The bottom of the open area of the bay is primarily covered by a combination of seagrass, macro-algae, and sand mounds, which are mainly created by marine worms like the Southern Lugworm (Arenicola cristita) and other bottom organisms.
The seagrass beds are especially important for the internationally protected creatures the Hawksbill sea turtle (Eretmochelys imbrotica), theGreen turtle (Chelonia mydas) and the Queen Conch (Strombus gigas).

Sea turtles, especially Green sea turtles, are one of the very few animals that eat seagrass. Seagrass is a rich source of calcium and other minerals important for a healthy carapace development.
Seagrass needs to be constantly cut short to be healthy and to help it grow across the floor of the open Lac area, rather than just growing longer grass blades. Sea turtles act as grazing animals that cut the grass short and help maintain the health of the seagrass beds. Seagrass beds are important because they provide breeding and developmental grounds for many species of fish, crustaceans (e.g. crabs, mud and pink shrimp and lobster), mollusks (Queen Conch) and shellfish. Even juvenile seahorses (Hippocampus erectus) and juvenile lobsters (Panulirus argus) are found in the seagrass beds but are rarely spotted.

Around sunset big predators, such as Tarpons (Megalops atlanticus) and Great Barracudas (Sphyraena barracuda), enter the open area of Lac to prey on smaller fish. Even Spotted Eagle Rays (Aetobatus narinari) visit Lac to dig in the sand for mollusks.

The Coral dam:
Snorkelling on the coral dam of Lac is an unforgettable experience. Most of the reef fish you find in the rest of the Marine Park are present in this area of Lac in a juvenile, intermediate or terminal phase. Greater densities of various reef fish species are to be found here as well. Schools of up to ten Porcupine fish (Diodon hystrix) or Rainbow Parrotfish (Scarus guacamala) gathered around one single brain coral head are not an unusual occurrence.

The coral at the coral dam of Lac is in pristine condition. Corals are by far the most abundant animals on Bonaire. If you want to have a close look, the coral dam at the end of Awa Blanku is the best place for a snorkelling trip.

Corals are ocean animals that look like plants and stay rooted to one place like plants. Some are branching, some are fan-shaped, and some are shaped like brains.

Coral reefs are really active communities under the waves. The corals are tiny creatures (polyps) living on and in the reefs. These animals live together in colonies in the sea. Every single polyp extracts calcium from seawater and deposits this beneath itself as a limestone skeleton (exoskeleton). The polyps of one coral head are all linked together into one giant colony. As the corals die, new generations arrive and settle on top. Little by little, the reef builds up this way. Over time, gaps in the exoskeletons fill in and the reef turns to limestone, which is visible all around the island of Bonaire.

The limestone structures produced by ‘stony’ corals provide a perfect home for tiny bottom dwelling animals as well as being a safe haven for the dazzling array of reef fish you see swimming above the reefs.