Ecosystems at Risk - The Great Barrier Reef
By Rhiannon Stewart-White

Introduction: Every ecosystems functioning is dependent on the Earths four complex overlapping spheres, (the atmosphere, lithosphere, hydrosphere and the biosphere.) These linkages enable ecosystems to work in a state of dynamic equilibrium. An ecosystem is the intense link of biotic and abiotic environments. A major ecosystem and tourist attraction in Australia is The Great Barrier Reef, which roughly covers an amazing 2300 kilometres making it the Worlds largest reef. The reef is home to an extremely wide range of animal and plant species and is known for its diversity. The reef is the largest living organism on the planet.

The Biosphere

The independent spheres of the earth interact together causing the functioning of diverse ecosystems. Changes in one sphere can cause changes in other spheres. The biosphere is created and maintained by the interactions with the gases from the atmosphere, the minerals of the lithosphere, and water of the hydrosphere.

Atmosphere

The atmosphere is a blanket of a combination of gases, such as; nitrogen, oxygen, water vapor, carbon dioxide, ozone, and more small quantities of other gases that surround the Earth protecting it from excessive amounts of radiation reaching the Earths surface. Thereby it allows life to thrive on our planet. The atmosphere is the main cause of climatic factors that contribute to ecosystems functioning. The determination of how well an ecosystem runs is based on the temperature, the movements of air masses and pressure systems and amount of rainfall that the environment is exposed to. Although the atmosphere has the main effect on ecosystems, the hydrosphere and lithosphere also interact and impact the functioning of an ecosystem.
Due to the location of the Great Barrier Reef, it faces both positive and negative interactions with the atmosphere. The reef lies in an area classified as Australia’s Cyclone Zone, an area hit by many fierce storms in its past. The degree of impact on the reef is subject to the intensity and extent of the storm. The damage occurs due to large storm waves that are produced from strong winds and low-pressure systems. The forceful waves rip apart the more fragile coral and create chips and imperfections in the harder coral. In severe cyclone cases the whole reef ecosystem may be put under sediment. Tropical cyclones are known for having heavily-induced rain cycles (hydrosphere). The extra volume of fresh water means that the salinity of the reef ecosystem is then distorted, and affects coral growth. The atmosphere can also be a constructive interaction. For example in 2006 Cyclone Larry hit the shores of North Queensland. The cyclone struck the reef, but instead of causing destruction within the ecosystem, the cyclone prevented mass coral bleaching from occurring by lowering the temperature of the water. Atmospheric pressures lead to greater functioning ecosystems through adaptation. Below is a diagram of the carbon cycle.

Lithosphere

The lithosphere is the upper portion of the Earth’s mantle; it’s the solid outer shell of the Earth’s surface. The lithosphere is made up of plates, these plates move against each other, causing some regions of the Earth's surface to rise and others to fall. The Great Barrier Reef has two main lithospheric processes that occur in the ecosystem, Earth movements and weathering and erosion.
Earth movements that have affected the Great Barrier Reef in the past are processes such as subsidence. Subsidence is the process of the lithosphere sinking due to the amount of sediment settling or a greater weight being placed on the reef. Sediment like sand can have the effect of clouding up the water of the reef resulting in increased turbidity levels of the water. There is then less sunlight penetration into the reef, affecting the process of photosynthesis and coral bleaching is more likely to occur.
Weather and erosion are also