Importance of Coral Reefs
Corals are considered to be the "rainforests of the ocean" and contain a diverse group of organisms that rely on corals as a source of food and shelter. In addition to the hundreds of species of corals, they are home to a multitude of animals (approximately 25% of all marine life) including sponges, cnidarians, worms, crustaceans, molluscs, echinoderms, tunicates, sea turtles and sea snakes. Corals are thought to house over 4,000 species of fish alone!
Reefs are important for several different reasons:
Reefs are important for several different reasons:
- protect the shoreline, minimizing wave impacts from storms.
- provide habitats and shelter for 100s of organisms, this also helps ensure fish for commercial fishing
- attract tourist/important for tourism (provides jobs and economical growth)
- provide food for those who live close to the reef
- many potential treatments for illness and disease
Many factors are affecting coral reefs causing stress upon that ecosystem. Factors include:
- overfishing; this has upset the balance in the food chain allowing for a high level of algae growth on the corals (essentially "choking' them). Also overfishing for aquariums has become a problem
- destructive fishing techniques such as dynamite break up corals
- unsustainable tourism; careless divers, boat anchors, and untreated sewage all damage the reef
- coastal development; development may alter water flow which can affect nutrient and sedimentation influx. Also some developers are building on "reclaimed" land or dredging the water to make deep channels for boats
- Pollution; corals need clean water to thrive
- Coral disease such as the "white plague"; disease occurance has increased due to the onset of bacteria or viruses that thrive in polluted waters
- Crown of Thorns Starfish; a coral reef predator that has few predators due to overfishing
- Invasive species which affects the balance of this delicate ecosystem
- Ocean acidification; a decrease in the ocean's overall pH due to the ocean absorbing excess Carbon Dioxide out of the atmosphere. This increase in acidity can break down the coral's skeleton.
- Rising sea temperatures; this warming causes sea levels to rise and creates problems for the reefs and its organisms (these are shallow water organisms!) Excess coral stress occurs when temperatures around the coral exceed 1 degree C for more than 4 weeks.
What happens if a coral gets too stressed?
Stress can be caused by a variety of factors including a change in temperature, pH or salinity. When corals get too stressed they will expel (kick out) their zooxanthellae which results in a loss of food. The corals, essentially, starve themselves. Since the algae is the primary contributor to the coral's color, the "empty" coral appears white or bleached. Some corals can come back from stress but in severe cases (like those caused by sea surface temperatures), the coral reef will die.
Stress can be caused by a variety of factors including a change in temperature, pH or salinity. When corals get too stressed they will expel (kick out) their zooxanthellae which results in a loss of food. The corals, essentially, starve themselves. Since the algae is the primary contributor to the coral's color, the "empty" coral appears white or bleached. Some corals can come back from stress but in severe cases (like those caused by sea surface temperatures), the coral reef will die.