Biophysical Interactions on the Reef
Ecosystems At Risk Reefs are important ecosystems as the are home to an immense amount of biodiversity and are essential in the cycle of life The Role of the Atmosphere Many reefs are located in the cyclone zone due to the necessary conditions they require to grow. For as long as reefs have existed they have been shaped by cyclones and intense storms. The severity of the storms and cyclones is determined by the length and intensity of the storms, which determines how much damage will be inflicted onto the reefs. The cyclones and storms generate large waves and strong winds, which do most of the damage to the reefs.
The waves have the power to rip apart soft coral and chip and damage the harder coral. Sometimes cyclones may result in large amounts of the reefs systems being buried by sediment. Reefs are very delicate and need very precise conditions to live and grow, the amount of rain that is associated with intense low systems can flood the reef with fresh water and reduce the salinity levels. During the storms the turbidly of the water also increases so the sunlight cannot reach the coral reducing its ability to produce food.
Tropical cyclone Larry (2006) showed that reefs could benefit from storms. The waves that were produced by Larry removed sediment that had accumulated and reduce the water temperature to the ideal level. The Role of the Lithosphere The role of the lithosphere in forming and transforming the reef ecosystem is very important. The reefs build themselves, this works because when the coral dies it produces limestone which the new coral grows on. The limestone is also weathered down and redistributed to other parts of the ecosystem to create a range of other landforms.
Through the production of limestone coral reefs are able to withstand the erosive power of waves. Overtime individual corals will of course die but this will allow the growth of new coral on the stable limestone structures the leave behind. Sediment is also an important influence on the reef. Sediment such as sand and mud can cloud the water creating high turbidity. High levels of turbidity can reduce the suns ability to penetrate the water and thus effecting zooxanthellae’s photosynthesis. Coral reefs may also be smothered by sediment especially were the possibility of high runoff is likely.
This is why in monsoonal areas and areas with high precipitation levels there are not many fringing reefs as they would struggle to cope with the change in salinity levels from the fresh water and the sediment increasing the turbidity levels. The Role of the Hydrosphere Coral reefs grow best in high wave energy areas. Reefs are very effective at interfering with wave energy. The structure of the reef is such that the seaward part of the reef absorbs much of the energy leaving an area of calm water behind it.
The amount of water that flows across the reefs is so enormous that it is measured in cubic kilometres. The flow of the currents is very important to the reef ecosystem. When the currents flow in a direction that they bring warm waters, high saline levels and high levels of nutrition that is a huge contributor to the biodiversity that makes the reefs so important and unique. The Role of the Biosphere There are more then 330 species of coral that can be found in any one reef. The coral is a living animal called Polyps.
Polyps are primitive organisms that consist of little more then a digestive sac and an out skeleton made from limestone. The Polyps feed by pulling food into its mouth through tentacles. Within the polyps lives an alga called zooxanthellae, the algae produces sugars and oxygen through photosynthesis. The polyps provide shelter for the algae and in return receive nutrients and the alga is also what gives the coral the distinct colours. Each coral reef begins as a single polyp, which reproduces itself to create a colony.
Apart from coral reefs are highly diverse systems made up of thousands of species. The amount of nutrients created by the plants and algae on the reef is several times that made in the open ocean. Because of the high levels of nutrients available on the reef there are thousands of fish species that feed on the nutrients produced and even the coral. Due to the abundance of fish some top order predators such as sharks and dolphins come to the reef. There are many different species living on reefs that work to keep the balance of life on the reef.