Corals are tiny animals that live in colonies and derive nourishment and energy from a symbiotic relationship with zooxanthellae algae. Coral reefs are formed over the course of thousands of years as limestone skeletons constructed by corals accumulate and form a structural base for living corals. Coral reefs are one of the richest, most diverse and most productive ecosystems in the world.
WHY CORAL REEFS ARE CALLED RAIN FORESTS OF OCEAN
1. Just like tropical rainforests perform important functions in terrestrial ecosystems by hosting millions of species, regulating temperatures and absorbing co2 and greenhouse
gasses, coral reefs also perform important functions in marine ecosystems.
2. Coral reefs cover less than one percent of the ocean floor and yet support an estimated 25 percent of all known marine species.
3. The variety of species living on coral reefs is greater than almost anywhere else in the world.
Scientists estimate that more than one million species of plants and animals are associated with coral reef ecosystems.
4. Corals are one of the most productive ecosystems on Earth, providing important services to humankind including fisheries, coastal protection, medicines, recreation, and tourism.
5. Because of this diversity and the essential function they perform in the marine ecosystem coral reefs are called rainforests of oceans.
FACTORS INFLUENCING CORAL LIFE
1. Natural factors: Coral reefs require ample sunlight to perform photosynthesis, warm water temperature, and salinity over 20ppm. Sediment-free water and a hard stable bottom for substrate attachment.
2. Anthropogenic factors:
a) Overfishing and Destructive Fishing Methods: Overfishing by commercial producers in shallow waters and unsustainable and destructive fishing methods such as dynamite fishing are not only depleting species of fish vital to the health of the reef ecosystem but also affecting the physical structure of reefs.
b) Climate Change: A warming ocean is causing thermal stress that is contributing to coral bleaching and infectious disease. Over 2016 and 2017, the Great Barrier Reef suffered back-to-back bleaching, leaving half of the shallow water corals dead.
c) Tourism: Unsustainable and irresponsible tourism practices like an increase in careless tourists, not being educated on how to safely interact with the reefs, tourists dumping waste into the water causing water pollution etc are affecting coral life.
d) Pollution: The drastic increase in urban and industrial waste, oil pollution due to oil spills, and the throwing of trash in the ocean are taking a huge toll on coral reefs either through eutrophication or by decreasing access to sunlight.
CORAL BLEACHING
1. When corals are stressed by changes in conditions such as temperature, light, or nutrients, they expel the symbiotic algae living in their tissues, causing them to turn completely white. This phenomenon is called coral bleaching.
2. The leading cause of coral bleaching is climate change. A warming planet means a warming ocean, and a change in water temperature can cause coral to drive out algae.
3. Coral may bleach for other reasons, like extremely low tides, pollution, too much sunlight, or the addition of freshwater due to precipitation or storm-generated runoff.
4. Coral bleaching matters because once these corals die, reefs rarely come back. With few corals surviving, they struggle to reproduce, and entire reef ecosystems, on which
people and wildlife depend, deteriorate.
5. According to the National Oceanic and Atmospheric Association, between 2014 and 2017 around 75% of the world’s tropical coral reefs experienced heat stress severe enough to trigger bleaching. For 30% of the world’s reefs, that heat stress was enough to kill coral.
Limiting global average temperature to well below 2°C above pre-industrial levels, sustainable tourism and fishing practices and efforts to clean our oceans, are some of the urgent steps we need to take to preserve this extremely important marine ecosystem.