Biodiversity

The biodiversity of a coral reef is pretty straightforward: It is extremely high. In fact, many scientists believe that coral reefs are the highest center for biodiversity on the planet, passing tropical rainforests! Although reefs cover less than one percent of the ocean, they are responsible for around 25 percent of all marine life known on earth. For example, coral reefs make the home for 4,000 species of fish alone. In total, millions of species call the coral reef their home.

The Carbon Cycle (Reef Style)

The carbon cycle in a coral reef is an extremely large part of the ecosystem. Essentially, carbon dioxide (g) that is formed by combustion of fossil fuels dissolves into the ocean water. Then, the phytoplankton, seagrasses, and algae take in the carbon dioxide as a part of photosynthesis to produce oxygen, and in turn the oxygen is used by consumers to breathe. The carbon dioxide they breathe out can either transform back to air or stay dissolved for the use of producers. When the animal dies, they sink to the bottom and are recycled by decomposers. Eventually, they can become part of the carbon fossil which is then brought up for anthropogenic use. This is the organic part of the carbon cycle. The inorganic part in coral reefs includes calcification, or the building of shells. Calcium ions and carbonate combine to form calcium carbonate, the building block of shells for organisms like clams and mussels. 

The Limiting Factors

Now, to get an idea of the living conditions of a coral reef, we are going to go through the abiotic and biotic factors of this ecosystem. Abiotic limiting factors include salinity of the water, temperature, depth, waves, and translucency. In coral reefs, salinity levels range from 34 to 37 parts per thousand. Temperature usually never gets below 20℃ or above 28℃, which means that almost all reefs are located in between 30°N and 30°S. Coral reefs also form where there are waves crashing because waves bring in nutrients and plankton that are vital for a reef to thrive, and these areas are usually no deeper than 45 meters. Lastly, the water must be clear enough for light to get through to wherever the reef is because it relies on phytoplankton's and algae's photosynthesis as its main source of energy. PH (around 8.4) is another factor, any changes in pH can drastically change/harm the reef environment.

Next, the biotic limiting factors of the coral reef. Biotic factors have to do with living things; for example how many sharks there are to control the populations of fish, or how much phytoplankton there is to produce enough energy for the rest of the food chain. In addition, biotic factors of a reef can be the amount of coral (coral is living), since coral forms a home for a large majority of the animals. If there is only so many coral structures, only so many fish can make a home there. Biotic limiting factors are largely predator/prey related. Either the amount of predators can control a prey population, or the amount of prey available can also control the predator population.

The Different Types of Reefs

To start off our exploration of the coral reef, let us first identify the three different types of reefs. First, perhaps the most well-known around the world is the barrier reef (Great Barrier Reef, AUS!) that is separated from the shore by a channel or lagoon.

Next, there are fringing reefs, such as those in the Bahamas. The particular fringing reef pictured below is off of the coast of Israel. Fringing reefs have very little space between them in the shoreline or practically sprout up off the shoreline.

Lastly, atoll reefs completely surround a lagoon. They are often formed over old volcano tips and are found mostly in the Pacific Ocean. Well, there ya have it! Next, we will go into the abiotic and biotic factors of these incredibly diverse reefs. Check back soon!