Indian River Lagoon

Lagoon Habitat
Indian River Lagoon

The Lagoon has more species of plants and animals than any other estuary in North America, including over 2,200 animal species and over 2,100 plant species. Since it is located where the temperate and tropical zones overlap and located within the Indian River Lagoon at the confluence of freshwater and saltwater sources, the refuge is uniquely situated to support a wide variety of resident and migratory species. 

Some of the most extensive sea grass beds of the Lagoon are found within the refuge, including manatee grass, turtle grass, shoal grass and the threatened Johnson's sea grass, found nowhere else in the world. These sea grass communities provide spawning, nursery, and foraging habitat for many aquatic species, including spotted sea trout, redfish (red drum), snook, tarpon, mullet, sheepshead, pompano, seahorses, blue crabs, hermit crabs, pink shrimp, scallops, clams, marine worms, marine snails, and other crustaceans. Manatees and juvenile sea turtles are commonly found foraging in these areas. 

Oyster bars, made up of the filter-feeding mollusks, help cleanse the estuary and stabilize shorelines. They also provide habitat for other species of mollusks, crustaceans, which support some shorebirds and waterfowl.
Salt marshes with the associated tidal creeks and mud flats consist of such marsh plants as smooth cordgrass, saltgrass, saltwort and glasswort. Salt marshes also provide abundant food and cover for a wide variety of resident and transient wildlife, including fiddler crabs, marsh rabbits, many wading birds, and shorebirds.


The mangrove habitats include three true species of mangroves that play a vital role in the food chain of the Indian River Lagoon and also in the growth and development of many aquatic organisms. Microorganisms, which feed on decaying mangrove leaves, become food for shrimp, crabs, snails, and worms. They in turn become food for many species of fish, which support numerous wading birds in the refuge.

Mangrove trees contain several different communities of life from their roots to their canopy. The distinctive roots of the mangroves provide habitat for oysters and barnacles and sheltering habitat for many species of juvenile fish. The trunk and branches of the tree provide habitat for periwinkle snails, mangrove crabs, and mangrove snakes. The tree canopies provide nesting habitat for many species of birds. 

Each mangrove species have unique adaptations to survive in the harsh saltwater environment. Red mangroves are most common along the shorelines and basins. They have prop roots that help provide oxygen, exclude salt and provide a stable foundation. Their distinctive cigar-shaped propagules are actually seeds that have already germinated before hitting the ground. They excrete salt through a system of sacrificial leaves.

The black mangroves, predominant on natural islands (including Pelican Island) just above the tide line, have a lateral root system with pneumatophores that thrust above the ground, giving the appearance of standing on a bed of spikes. They excrete salt through the underside of their leaves. The white mangrove is found further ashore and excretes salt through pores at the base of their leaves.

Pelican Island National Wildlife Refuge is in a critical location to serve and support biological diversity in the Indian River Lagoon and South Florida. As a result of multiple causes and threats, many species endemic to the southern Indian River Lagoon have become extinct, endangered, or threatened under the Endangered Species Act. The refuge supports at least 14 federally threatened or endangered species. Further, the refuge also supports 45 species listed by the State of Florida as either threatened, endangered, special concern, or commercially exploited. 

Facts About Indian River Lagoon

Part of the South Florida Ecosystem, Pelican Island National Wildlife Refuge is located within the southern Indian River Lagoon.