Coral reefs are special ocean ecosystems where many marine species thrive, and upon which many more marine species are dependent. Sometimes referred to as “sea gardens,” coral reefs house exceptional biodiversity in the normally nutrient poor tropical waters. Coral reefs are found most often in tropical waters, with a great number of reefs in the Asian pacific.

The coral itself is actually a group of organisms living together, not a single organism. Coral is made up of the coral skeleton and the coral polyps, tiny little creatures that look like sea anemones and create calcium carbonate exoskeletons that make up the larger coral structure. Each generation builds upon the previous generation, and that is how the coral reefs “grow.”

To make things even more confusing, the coral polyps, though they can capture some tiny plankton, receive most of their nutrients from dinoflagellates, photosynthesizing algae, that live with the polyps in the coral. Like lichen, the two animals live so intertwined that for decades scientists assumed they were one organism. Neither can live on its own, but depend on each other for survival. The dinoflagellates depend on sunlight, and this is why most coral reefs are found in shallow waters where the sunlight can penetrate.

Like rainforests and wetlands, coral reefs have a high “recycling” rate for nutrients. This allows biodiversity to thrive, though the ecosystem is relatively low in nutrients. Producers, essentially plants that photosynthesize, form the base for any food web and are found in abundance in coral reefs, for example algae and seaweed. The producers provide food for the abundant small fish and marine life, which in turn provide meals for the larger animals.

Coral reefs are also important indicators of ocean health, and even the health of the planet overall. Coral reefs are to the earth what canaries are to the mines. Pollution is one of the top causes of coral bleaching, a phenomenon that occurs when the polyps die out and only the coral skeleton is left. The coral skeleton is simply calcium carbonate, and is white, while the polyps provide the great variety of color to coral reefs. Most of this pollution is due to poor land management and excessive chemical herbicides, pesticides, and fungicides in developed areas. As the watershed collects and delivers the water to the oceans, pollutants are also delivered.

Another risk for the coral reefs is over fishing. Tropical reef fish are popular fish for aquariums, and as a result of increasing demand for these fish in Western Europe and North America the fish are captured and sold. Chemicals such as cyanide are used to stun the fish so they are easily captured, but this chemical damages the coral reefs. These divers also destroy reefs in an attempt to scare the fish out of the reefs or capture the stunned fish. Because many of the world’s coral reefs are nearest to developing countries in Asia, it is difficult for governments and organizations to enforce protection laws.

Worldwide problems such as ocean water acidification and increased global ocean temperatures also contribute to the decay of this fragile ecosystem. Taking action to decrease land water pollutants would drastically improve ocean and coral health. Also supporting worldwide limits on fishing and fishing practices would allow only sustainable fishing to take place, protecting coral and giving fish a chance to reproduce and keep their populations at healthy levels, ensuring fish well into the future. Actions to reduce greenhouse gases would also help reduce global warming and therefore ocean warming. While many obstacles are difficult to overcome, making minor changes in everyday living can change the fate of the planet. The coral reefs are our warning system – if they can’t survive, we are on our way to inhospitable planet. But if we can protect our reefs, we can all thrive in a healthy world, and enjoy the beauty of the sea gardens for generations to come.