Coral reef plants exist on three types of reefs including: fringing reefs, barrier reefs, and atolls. Fringing reefs such as those located in the Bahamas are within a short distance from shore, with outward and upward growth of reef plants, coral, and organisms. Barrier reefs, such as the Great Barrier Reef off the coast of Queensland, Australia, are detached from the coastline by a lagoon, and grow parallel to the shoreline. Atolls are circular reefs that surround island lagoons and are formed atop volcanic surfaces that have sunken below sea level. Lagoons, back reefs and outer reefs offer clear water that safeguards reef plants and coral from heavy currents, so that sea grass beds and algae can perform photosynthesis and aid in the growth and defense of coral in varying water depths.
Reef plants grow in combination with coral, requiring clear, shallow water with temperatures of 75 degrees or higher. Water salinity is needed for coral and reef plants to thrive, making the saltwater of the Caribbean, Indo-Pacific, and Coastal Atlantic regions of Florida and the Florida Keys efficient habitats that benefit from a year-round tropical or sub-tropical climate due to close proximity to the equator. Coral reefs are considered to be ocean rainforests, as the shallow depths allow for sunlight to reach sea grasses and algae, promoting the process of photosynthesis.
Symbiosis refers to the mutually dependent connection between two organisms. Coral and zooxanthellae, a type of reef algae, benefit from such an association. Coral reefs are found in low depths due to the symbiotic relationship of coral and zooxanthellae. Shallow, clear water allows sunlight to reach zooxanthellae so that photosynthesis can occur in support of healthy coral. Algae live inside coral polyps and provide food and oxygen for the coral while the coral helps emit light and carbon dioxide needed for photosynthesis to occur. Protective algae share color with coral, preventing bleaching that can lead to the disease and eventual death of coral.
Coral reef sea grass plants such as sargassum and thalassia provide leaves to camouflage fish and invertebrate species that live and reproduce in nursery beds of the shallow plants. Calcareous reef algae produce calcium carbonate, and hold branching corals in place by growing in between the base of the coral, strengthening and fastening it to the seafloor. This process protects coral from being detached by tides, runoff and erosion. Mangroves are plants that grow near coastal waters and provide a habitat for other plants and fish, protecting small fish from larger predator species so that they can survive to become part of the reef fish ecosystem. Coral reef systems protect the mangrove areas from being destructed or uprooted by heavy tides and waves, allowing for the growth of marine populations.
Plants are an important food source for many ocean organisms. Zooplankton is a microorganism that feeds on algae within reef ecosystems, and coral sustains itself by preying on zooplankton. As coral becomes endangered by storm surges, human destruction, and climate changes, the food chain and ecosystem of plants and fish living within the biome are increasingly disrupted, negatively affecting economy, environment and health. Without coral and the reef plants that support and protect the delicate marine environment, the oceans will experience an imbalance in carbon dioxide, coastlines will be unprotected from wave surges and natural reef systems that act as barriers between land and the open sea will be non-existent, allowing for rises in sea level that may eventually submerge inhabited land.
