‘Coral reef plants’ is a term commonly used to describe both flowering plants and algae present in coral reefs. Plants serve a vital role in the ecosystem, providing oxygen to others they share symbiosis with, such as corals, as well as eliminating waste and transforming it into glucose and other compounds essential for the ecosystem.
Seagrasses are one of the two types of green plants to contribute extensively to the ecosystem of a reef. They form vast meadows in the protected waters at the back of a reef, providing a home as well as a foraging ground to many species of fishes, marine reptiles like turtles and even mammals such as manatees.
The other group of flowering coral reef plants are mangroves, a type of shrub uniquely capable of tolerating – even thriving in – salt water. They have adpted specialized salt-filtering roots for this exact purpose. The complex system of roots under a mangrove forest serves as a breeding and nursing ground for young reef fishes. Mangroves are likewise vital in the formation of new islands and shorelines within a coral reef lagoon.
More commonly knowns as seaweeds, these algae are extensively present in coral reef ecosystems and are categorized into three main types:
Green algae: Abundant in shallow water areas, these algae can be found clinging onto rocks and corals, as well as directly on the ocean floor. Green algae are classified as “green plants”, along with all land plants.
Red Algae: The most common of this type of algae are crustose coralline algae, which construct exoskeletons made of calcium carbonate just like most corals. These coral reef plants directly contribute to the formation of reefs.
Brown Algae: These less common algae are vital to the ecosystem both as food and as habitats and hiding places for small fish and other creatures.
Forming the largest part of the biomass of algae in a reef, Zooxanthellae are microscopic forms living in symbiosis with coral polyps. They provide the coral with oxygen and compounds such as glucose, and help dispose of the waste (which contains many organic products essential for photosynthesis) in exchange for a safe heaven within the coral’s exoskeleton and carbon dioxide produced by the corals. The compounds supplied by the Zooxanthellae are vital to the coral’s efforts of building calcium carbonate – the building blocks of the hard exoskeleton, the actual reef.
Coral reef plants are critical for the ecosystem and the survival of the reef, acting as primary producers, homes, food and waste disposal.