“Think about this: if the water is the blood of our planet flowing through veinous rivers, streams, and into our oceans, what does that make coral? Our heart. We simply cannot survive without our heart; therefore, it’s mandatory we heal and protect our coral reefs now.~ Ian Somerhalder
Most of us consider “coral reefs” as warm, clear, shallow ocean habitats that are rich in life. However, it’s important to know that what are coral reefs actually; animal, mineral, or a vegetable? A coral is actually an animal that belongs to Phylum Cnidaria and lives fixed to the seabed instead of swimming free. Technically there can be two types of corals: rock hard corals and soft corals.
Reefs make up about only 0.1% of the vast ocean floor. Nevertheless, it should be emphasized that nearly 25% of all marine and aquatic life is dependent upon coral reefs for their survival. This is why they are often called “Rain forests of the Sea”.
Principle types of reefs include fringing reefs, barrier reefs, and coral atolls. Other variants include patch reefs, apron reefs, bank reefs, ribbon reefs, and table reefs. The reefs’ massive structure is formed from coral polyps; tiny invertebrate animals (i.e. no backbone) that live in colonies.
When coral polyps die, they leave behind a hard stony, branching structure made up of limestone (CaCO3). A single coral reef is about a million of these individual coral polyp shells as they stuck one on the top of the other.
Coral reefs develop in shallow warm water usually near land, and mostly in tropics. Healthy coral reefs grow horizontally from 1 cm to 3 cm per year and grow vertically anywhere from 1 cm to 25 cm per year. However, these warm-water corals are limited to growing above a depth of 40 meters because they need sunlight.
They cannot grow above sea level except for the deep and cold-water coral reefs which live at depths of 40 meters to 2000 meters in water temperature as low as 4 oC. The best temperature for coral reefs is between 18 oC to 31 oC and the best salinity is between 34-37 parts per thousand. Deep-sea corals, however, grow slowly (5 mm to 25 mm/year) but overtime they can form extensive reefs.
There are over 500 species of corals. Some look like brains, some tree-like fan,s and some like antlers of deer. These corals provide shelter for many animals in this complex habitat. The number of invertebrate species on reefs in the Northeast Atlantic Ocean can be as high as that found in shallow-water tropical reefs.
Although the number of fish species is relatively low in deep-sea corals (20 to 40 species compared to 3000 species on some tropical reefs). Coral reefs are estimated to cover an area of 284,300 sq. km in the ocean. They are found in about 100 countries and are considered to be the world’s most fragile and endangered ecosystems.
In the last few decades over 35 million acres of coral reefs have been obliterated from around 93 countries. Principle coral reefs and reef areas of the world include The Great Barrier Reef, The Belize Barrier Reef, Pulley Ridge, The New Caledonia Barrier Reef, The Andros-Bahamas Barrier Reef, The Red Sea Coral Reef and Reefs in the Maldives.
Pakistan is also blessed with coral reefs near the cleaner shores. However, public awareness of their presence and importance is still uncommon. Center of Excellence in Marine Biology of the University of Karachi has on-going programs consisting of experimental work of collecting samples, studying and classification of more than 30 species of corals found in the clean beaches of Pasni, Astola Island, and Charna Island near the provinces of Sindh and Baluchistan. Human beings are now utilizing artificial reefs to replace the coral reefs that have been destroyed due to anthropogenic activities. Most notable one of these is the ones from sunken ships which have become a habitat for reefs. Some other examples of artificially constructed reefs include tires or old appliances lined together and even discarded military equipment such as tanks and helicopters.
Coral reefs are of great economic and ecological significance. Not only they help in moderating atmospheric temperature by removing CO2 but also act as a natural barrier that helps protect 15% of the world’s coastline erosion by battering waves and storms. They provide jobs and building materials for some of the world’s poorest countries and also support the fishing and tourism industries. They support 10% of the world’s diet and untapped pharmaceutical resources for medicines.
Despite being magnificent and extremely useful, coral reefs are considered as an endangered species due to continuous destruction by human activities. Some of the major threats to coral reefs include coral mining, over-fishing, destructive fishing, practices like dynamite and cyanide fishing, ocean acidification, soil erosion, water pollution, sedimentation, mangrove destruction, coral reef bleaching, algae growth from fertilizer runoff, careless tourism and recreation, increased UV exposure from ozone depletion, coral removal for building material, aquariums and jewellery and damage from anchors, ships and tourist divers.
Our coral reefs are in crisis, dying at an alarming rate worldwide. They have survived tens of thousands of years of natural change but many of them may not be able to survive the havoc wrought by humankind.
At this stage, there is an extreme need for educating ourselves about them and ponder upon innovative solutions not only to save the coral reefs but also to make our oceans more sustainable.
Author: Rtr. Yashfeen Zahid
Rotaract Club of Karachi Innovators