Seagrasses are a specialized group of marine plants most often found in shallow, sheltered marine or estuarine waters.
In coral reef ecosystems, they occur within the protected back reef (lagoon) zone, where extensive meadows of these plants are often interspersed with areas of bare sand.
This forms a distinctive habitat type that serves as home or primary foraging ground for many species of coral reef fishes and invertebrate animals.
Seagrasses are fast growing plants capable of high production rates, making these meadows a key element in coral reef food webs. Also, by trapping suspended sediments and slowing water movement, seagrass meadows benefit nearby coral reefs by reducing sediment loads in the water.
Seagrass meadows play a key role in the lives of many reef animals, including fishes. Compared to coral reefs, seagrass habitats have little physical complexity. While still small, juvenile fishes of many species are able to utilize the limited shelter available in seagrass beds to good advantage. However, for larger fishes there is scarce shelter here above the grass blades save for the occasional sponge, octocoral, isolated coral colony, or occasional patch reef.
Thus, the animals active here by day are mainly small invertebrates and small fishes that rely heavily on concealment during daylight hours, typically either through camouflage or burrowing. At night however, many of the larger reef fishes that shelter by day on nearby patch reefs or outer reef zones forage here under the cover of darkness.
Seagrass meadows provide food and shelter for some of the most highly valued (commercially) species of invertebrates, including most notably conch and spiny lobster. They enhance the overall diversity and abundance of some of the invertebrate animals that serve as a primary food source for some coral reef fishes, particularly snappers and grunts. In addition, they also serve as habitat for some types of sea turtles.
Readers seeking more information on seagrasses are referred to our “Additional Resources” section, which contains lists of recommended readings specific to the topic of coral reef plants.