What Is a Coral Reef

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What is a coral reef Reefs are naturally formed by corals, small animals known as polyps and belonging to the phylum of Cnidaria; other emblematic members of Cnidaria are jellyfishes. Coral polyps can reproduce either by budding or sexually. During the mating season, corals release sperm and eggs into the water. When both sperm and eggs meet they will form a free swimming larva that will attach to a concrete substrate, generally a coral reef. Subsequently the coral will form its surrounding shell by combining carbon dioxide with calcium. They live in colonies and therefore form this accumulation of limestone known as coral reefs. An interesting fact about corals is that they host, within their tissue, a symbiotic unicellular algae known as zooxanthellea, which accounts for the reef coloration due to pigments it contains. Zooxanthellae provide their coral host with food and oxygen and in return, the zooxanthellae receive nutrients, carbon dioxide, and an enemy-free shelter. This symbiotic relationship evolved tens of millions of years ago and has been critical to the success and evolutionary radiation of corals, and to the development of reef ecosystems. Coral reefs require shallow and clear water for optimal growth and development. When the environmental conditions are not adequate (e.g. water temperature rise), the zooxanthellae will produce free radicals, triggering the coral polyp to release its symbiont; this phenomenon is known as coral bleaching because the coral animal appears to turn white after the zooxanthellae loss. Indeed, without their zooxanthellae symbionts, which contain various photosynthetic pigments, corals are nearly transparent and the white external calcium carbonate skeleton that the coral polyps live on becomes plainly visible. If the situation lasts too long it will eventually lead to the coral death as illustrated bellow. Coral bleaching process as a response to water temperature rise, reproduced from "A reef manager's guide to coral bleaching", 2006. Photo: A reef manager's guide to coral bleaching, 2006 .

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A Quick Guide to Southeast Florida's Coral Reefs
A Quick Guide to Southeast Florida’s Coral Reefs DAVID GILLIAM NATIONAL CORAL REEF INSTITUTE NOVA SOUTHEASTERN UNIVERSITY Spring 2013 Prepared by the Land-based Sources of Pollution Technical Advisory Committee (TAC) of the Southeast Florida Coral Reef Initiative (SEFCRI) BRIAN WALKER NATIONAL CORAL REEF INSTITUTE, NOVA SOUTHEASTERN Southeast Florida’s coral-rich communities are more valuable than UNIVERSITY the Spanish treasures that sank nearby. Like the lost treasures, these amazing reefs lie just a few hundred yards off the shores of Martin, Palm Beach, Broward and Miami-Dade Counties where more than one-third of Florida’s 19 million residents live. Fishing, diving, and boating help attract millions of visitors to southeast Florida each year (30 million in 2008/2009). Reef-related expen- ditures generate $5.7 billion annually in income and sales, and support more than 61,000 local jobs. Such immense recreational activity, coupled with the pressures of coastal development, inland agriculture, and robust cruise and commercial shipping industries, threaten the very survival of our reefs. With your help, reefs will be protected from local stresses and future generations will be able to enjoy their beauty and economic benefits. Coral reefs are highly diverse and productive, yet surprisingly fragile, ecosystems. They are built by living creatures that require clean, clear seawater to settle, mature and reproduce. Reefs provide safe havens for spectacular forms of marine life. Unfortunately, reefs are vulnerable to impacts on scales ranging from local and regional to global. Global threats to reefs have increased along with expanding ART SEITZ human populations and industrialization. Now, warming seawater temperatures and changing ocean chemistry from carbon dioxide emitted by the burning of fossil fuels and deforestation are also starting to imperil corals.
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