Coral Reef Plants

On healthy reefs, coral reef plants are inconspicuous and appear heavily outnumbered by an abundance of animal life.

This is in stark contrast to familiar terrestrial biomes such as forests, prairies, jungles, etc. - biomes heavily dominated by a rich abundance of plant life that forms the base of their food chains.

Where then on coral reefs is the plant life that ultimately must provide nutritional support for the rich abundance and variety of animal life found in coral reef biomes?

In truth, coral reef plant life is actually abundant and widely distributed throught the entire reef ecosystem. But unlike coral reef animal life (which is readily apparent to the snorkeler or scuba diver), the true abundance and distribution of coral reef plant life can only really be appreciated by looking at coral reefs at macro (ecosystem) and micro-scale levels.

Main Types of Coral Reef Plants

There are three very different types of plants widely associated with coral reef ecosystems: marine algae, seagrasses, and mangroves.

A. Marine Algae

A variety of forms of marine algae are always present in coral reef ecosystems; in fact, a few types are essential to the survival of corals and the formation of coral reefs.

Coral reef algae. Courtesy NOAA

Within those parts of coral reef ecosystems where most hard coral growth is found (the reef face and reef crest), plant life exists only in the form of marine algae.

Most of this algal growth exists in the form of tiny microalgae. Macroalgae is also present, but in terms of biomass macroalgae is a relatively minor component of the plant life of healthy reefs.

The singular exception to this generality are the coralline algae, a specialized type of macroscopic red algae that actually helps build coral reefs and is a generally present in considerable amounts. It is this type of algae that often forms a prominent algal ridge on the perimeter reefs of oceanic atolls.

Marine algae forms a major link in coral reef food chains; many coral reef fishes and invertebrate animals utilize algae as their primary food source.

Because of their prominence as coral reef plants, we have devoted an entire separate page to coral reef algae.

B. Seagrasses

Seagrasses are an ecologically important component of many coral reef ecosystems.

Seagrasses. Courtesy NOAA

Like mangroves, the distribution of seagrasses is restricted to the protected waters of the lagoon, where they form a highly productive (and often extensive) habitat-type that supports a broad diversity of other forms of animal and plant life.

Seagrass meadows can form critical nursery grounds for reef fishes, conch, spiny lobster and other commercially valuable species.

C. Mangroves

Mangroves. Courtesy NOAA

Mangroves are shoreline plants, and thus are often (except on fringing reefs) quite distant from the main biomass of hard corals that form the massive reef crest and fore reef.

However, when present these plants have the capacity to considerably enhance the abundance and diversity of reef fishes and other types of marine life throughout the coral reef ecosystem.

A more thorough treatment of mangroves and seagrasses is provided on our page on the "back reef zone", which discusses mangrove forests and seagrass meadows as coral reef habitat types unto themselves.

Summary

Coral reef plants are in truth omnipresent in coral reef ecosystems, but it is only within the shallow, sheltered back reef zone do we find two kinds of obvious plant-dominated habitat-types (mangrove forests and seagrass meadows) of the size and extent that we associate with those that characterize most terrestrial ecosystems. These two major types of plant assemblages are discussed in greater detail on another page of our web site (back reef zone)

An ecosystem-scale perspective on the respective contributions of all three types of coral reef plants to overall energy production and nutritional support of the coral reef community is discussed in greater detail in our section on the coral reef food web.