Describe the spatial patterns and dimensions of one (1) ecosystem at risk, and analyse the negative impacts of human activity on this ecosystem. One ecosystem at risk that has been studied is the coral reef; The Great Barrier Reef is located off the East coast of Northern Queensland. It stretches approximately 2300km from Papua New Guinea to Fraser Island. Overall the Great Barrier Reef system covers an area of over 348,000km2 making a vast, very complex ecosystem. There is a long history of human activity and use on and of the Great Barrier Reef. Negative impacts on the Great Barrier Reef include climate change, oil spills, tourism, overfishing, land clearing, sewage and waste disposal, coral harvesting and dredging and sand mining.
Climate change has impacted Northern Queensland and the Great Barrier Reef as it increases in sea temperature, increases in average sea level, has a change in rainfall patterns. It changes the ocean currents and circulation, which has an increase in El Nino events which cause extreme weather and can damage the reef and cause a large amount of run off from the land, causing turbidity, lowering of salinity on the reef and increased amount of sediment. Extreme weather conditions can also increase the CO2 levels which can also change the chemical structure of the Great Barrier Reef causing coral bleaching.
On-going climate change will have and has already caused many consequences for the Great Barrier Reef. This change will and has directly impacted many species of fish, invertebrate, mammals and birds along with many aquatic and terrestrial plants. There are also substantial impacts on the functioning of the reef. The biggest concern about climate change and the Great Barrier Reef is the rise in sea temperature which will affect the movement of water around the reef and the nutrient cycle on the reef which also means the chemical structure which will be altered because of the increased amount of CO2 dissolved into the water.
With this and the rising sea levels, may be enough to destroy the reef, collapsing of the reef ecosystem. Recreational fishing is also a common past-time on the reef. When boats anchor on the reef, the heavy metal anchors damage the reefs coral formations and dredge up the sea grass bed. These boats are also a source of pollution through oil and oil spills, rubbish and sewage. The Great Barrier Reef Marine Park Authority estimates that around 6000 large commercial ships transit through the Great Barrier Reef each year. These ships can carry anything from grain, minerals, bulk cargo (such as cars) and oil.
Luckily there has not been a major oil spill on the reef. Ships also have the potential to bring with them feral aquatic species by releasing ballast water which is used to balance the ship containing these aquatic animals. Commercial fishing or overfishing has been an important economic activity for Queensland’s coastal communities. Unsustainable fishing practices in the past have left many areas of the Great Barrier Reef with decreased fish stocks. While many areas of the Great Barrier Reef are now off limits to commercial fishers, various areas of the reef can still be fished. Local fishermen are now no longer a major threat to the reef as they understand the need to protect the area’s fish stocks.
However, the reef still remains threatened by illegal fishing, which is often carried out by foreign fishing trawlers, and by unsustainable recreational fishing. Tourism is one of the most important industries in Northern Queensland and the Great Barrier Reef being ranked twelfth on the ‘Wonders of the World’ list brings a lot of tourism to Australia and especially far North Queensland. The economic value of the Great Barrier Reef exceeds more than $4 billion a year. In 2005, over 1.8 million tourists visited the reef. Research conducted by the James Cook University in Cairns has shown that tourism has five main impacts on the reef ecosystem; these are coastal tourism development, island-based tourism, marine based tourism, water-based activities and wildlife interactions.
Coastal tourism development is explained as tourists mainly visit and stay at mainland Hotels, Motels and Resorts, where this places a strain on coastal environments, including estuarine river systems. Island-based tourism is the growth of tourism on islands throughout the Great Barrier Reef, which creates problems associated with sewage and rubbish discharges. Marine based tourism is where tourist boat companies make thousands of journeys out to the Great Barrier Reef each year, which brings rubbish and a potential for oil spills.
These boats also require mooring points or anchor points on the reef which can destroy the coral. Water-based activities for explain diving and snorkelling are the most popular water-based activities on the reef. Most divers are very careful and usually cause no damage to the corals. However, studies have shown that a small proportion of divers swim too close to the corals, breaking them. The more fragile corals are susceptible to this. Wildlife interactions is the interactions with aquatic animals that live on the reef, most tourism operators are very careful to ensure tourists are well informed and to be strict with these rules and make sure that the tourists do not get too close to the wild animals that live on the reef, However, once again research shows that there are still a small portion of operators and tourists that are careless and disrupt wildlife which can impact on breeding cycles and natural interactions.
Other impacts of tourism on the Great Barrier Reef include trampling of coral. This is a common occurrence where people walk on the reefs and the coral that become exposed at low tide. Souveniring of coral, shells and other elements of the reef ecosystem was also a major problem. In the past tourists and some commercial traders took large amounts of materials such as corals, mostly from the inner reef, which has now been constituted as being illegal unless the collector is correctly licensed. There are 26 major river systems that flow into the waters of the Great Barrier Reef from mainland Queensland. Approximately 25% of the land area of Queensland drains onto the reef. This runoff represents a major impact on the reef. Coastal development on land adjacent to the reef is expanding rapidly.
Tourist developments such as those found between Cairns and Port Douglas, result in large amounts of land that is being cleared. The Great Barrier Reef Marine Park Authority has information and research that the clearing of wetlands is another major issue impacting on the sustainability of the reef. Intertidal wetlands provide important habitats and nurseries for many of thousands of species that liv eon or near the reef. These wetlands also hold a large amount of water reducing the amount of fresh water the Great Barrier Reef receives each year which keeps salinity levels stable. Aquaculture is becoming a more popular form of commercial farming.
Prawns, a number of fish species and pearl and edible oysters are commercially farmed throughout the Great Barrier Reef and in ponds near or next to the reef. These farms can sometimes release chemicals and diseases that impact and cause damage to the other species of aquatic life on the reef which can also cause pollution. Conventional agriculture on the coastal plain adjacent to the reef has been of great concern for reef ecologists and marine biologists.
The use of chemical fertilisers in the farming areas of the reef can increase nutrients that promote algae growth. The algae can and already has been smothering the reef which causes a decrease in light penetration for the corals to perform photosynthesis to grow. A type of agriculture that can dramatically harm the reef includes land clearing which results in the erosion of topsoil and an increase in turbidity levels in the water. There are a large number of negative impacts on the ecosystem at risk studied, but the Great Barrier Reef Marine Park Authority, along with other smaller groups including the Aboriginal Culture have been enforcing a number of ways to protect and create awareness to tourists, fishers and all people on or visiting the reef or surroundings to keep the ecosystem as stable as they can.