Coral reefA coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Coral belongs to the class Anthozoa in the animal phylum Cnidaria, which includes sea anemones and jellyfish. Unlike sea anemones, corals secrete hard carbonate exoskeletons that support and protect the coral. Most reefs grow best in warm, shallow, clear, sunny and agitated water.
Coral bleachingCoral bleaching is the process when corals become white due to various stressors, such as changes in temperature, light, or nutrients. Bleaching occurs when coral polyps expel the zooxanthellae (dinoflagellates that are commonly referred to as algae) that live inside their tissue, causing the coral to turn white. The zooxanthellae are photosynthetic, and as the water temperature rises, they begin to produce reactive oxygen species. This is toxic to the coral, so the coral expels the zooxanthellae.
Marine coastal ecosystemA marine coastal ecosystem is a marine ecosystem which occurs where the land meets the ocean. Marine coastal ecosystems include many very different types of marine habitats, each with their own characteristics and species composition. They are characterized by high levels of biodiversity and productivity. For example, estuaries are areas where freshwater rivers meet the saltwater of the ocean, creating an environment that is home to a wide variety of species, including fish, shellfish, and birds.
ReefA reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic (non-living) processes such as deposition of sand or wave erosion planing down rock outcrops. However, reefs such as the coral reefs of tropical waters are formed by biotic (living) processes, dominated by corals and coralline algae.
Ecological successionEcological succession is the process of change in the species that make up an ecological community over time. The process of succession occurs either after the initial colonization of a newly created habitat, or after a disturbance substantially alters a pre-existing habitat. Succession that begins in new habitats, uninfluenced by pre-existing communities, is called primary succession, whereas succession that follows disruption of a pre-existing community is called secondary succession.
Fringing reefA fringing reef is one of the three main types of coral reef. It is distinguished from the other main types, barrier reefs and atolls, in that it has either an entirely shallow backreef zone (lagoon) or none at all. If a fringing reef grows directly from the shoreline, then the reef flat extends to the beach and there is no backreef. In other cases (e.g., most of the Bahamas), fringing reefs may grow hundreds of yards from shore and contain extensive backreef areas within which it contains food and water, examples are Philippines, Indonesia, Timor-Leste, the western coast of Australia, the Caribbean, East Africa, and Red Sea.
Coral reef fishCoral reef fish are fish which live amongst or in close relation to coral reefs. Coral reefs form complex ecosystems with tremendous biodiversity. Among the myriad inhabitants, the fish stand out as colourful and interesting to watch. Hundreds of species can exist in a small area of a healthy reef, many of them hidden or well camouflaged. Reef fish have developed many ingenious specialisations adapted to survival on the reefs. Coral reefs occupy less than 1% of the surface area of the world oceans, but provide a home for 25% of all marine fish species.
Coastal managementCoastal management is defence against flooding and erosion, and techniques that stop erosion to claim lands. Protection against rising sea levels in the 21st century is crucial, as sea level rise accelerates due to climate change. Changes in sea level damage beaches and coastal systems are expected to rise at an increasing rate, causing coastal sediments to be disturbed by tidal energy. Coastal zones occupy less than 15% of the Earth's land area, while they host more than 40% of the world population. Nearly 1.
Pioneer speciesPioneer species are hardy species that are the first to colonize barren environments or previously biodiverse steady-state ecosystems that have been disrupted, such as by wildfire. Some lichens grow on rocks without soil, so may be among the first of life forms, and break down the rocks into soil for plants. Since some uninhabited land may have thin, poor quality soils with few nutrients, pioneer species are often hardy plants with adaptations such as long roots, root nodes containing nitrogen-fixing bacteria, and leaves that employ transpiration.
Primary successionPrimary succession is the beginning step of ecological succession after an extreme disturbance, which usually occurs in an environment devoid of vegetation and other organisms. These environments are typically lacking in soil, as disturbances like lava flow or retreating glaciers scour the environment clear of nutrients. In contrast, secondary succession occurs on substrates that previously supported vegetation before an ecological disturbance.
