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Thursday, July 31, 2008

Threats, water quality, run-off and climate change

Bleached Corals

The Great Barrier Reef is a vast interlinking web of life. All the plants and animals on the Reef play a part in keeping this web healthy and strong, and the relationships between different organisms on the Reef have been built and maintained over many thousands of years. Humans are relative newcomers to the Reef, and we've brought some big changes. Many things that we humans do on the Reef and on land have the ability to threaten the Reef's fragile ecosystem.On the Great Barrier Reef, careful management has made sure that most of our activities do not threaten the long-term health of the Reef's ecosystem.

Research has shown that tourism does not exert much pressure on the Great Barrier Reef because it is thinly spread over such a vast area. In addition, tourism operators have a vested interest in the health of the Reef, and act as watchdogs, alerting management authorities early if they see something going wrong.Fishing on the Reef is carefully managed by the Great Barrier Reef Marine Park Authority and Queensland Department of Primary Industries, so as to ensure that it will be sustainable for many generations to come.
Ironically, the biggest threats to the Reef mainly come from human activities on land.

Water quality and run-off
Sediments and nutrients, fertilisers, pesticides, toxic chemicals, sewage, rubbish, detergents, heavy metals and oil run through rivers and out to the Great Barrier Reef lagoon, where they are able to threaten plants and animals on the Reef. Land users and governments are now working together to try and improve the quality of water flowing onto the Great Barrier Reef as part of the Reef Water Quality Protection Plan.

Climate change
The Earth is getting warmer, and is now higher than it has been for 2000 years. A large body of research suggests that this is due to the greenhouse gases being released into the atmosphere by activities done by humans such as burning fossil fuels and deforestation. Even small changes in temperature can have a drastic effect on the natural environment. Even the rising of the Sea's temperature by just 1 or 2 degrees centigrade can cause coral bleaching as well as death, on a worldwide scale.

Tuesday, July 29, 2008

Threats to Coral Reefs

Corals and coral reefs are extremely sensitive. Slight changes in the reef environment may have detrimental effects on the health of entire coral colonies. These changes may be due to a variety of factors, but they generally fall within two categories: natural disturbances and anthropogenic disturbances. Although natural disturbances may cause severe changes in coral communities, anthropogenic disturbances have been a part of the vast majority of decreases in coral cover and the general colony health when coral reefs and humans occur together.

One of the greatest threats to coral reefs is human expansion and development. As human expansion and development continue to alter the landscape, the amount of freshwater runoff increases. This terriginous runoff may carry large amounts of sediment from land-clearing areas at times, high levels of nutrients from agricultural areas or septic systems, as well as many pollutants such as petroleum products or insecticides. Whether it is direct sedimentation onto the reef or an increase in the turbidity of the water due to eutrophication, it still decreases in the amounts of light able to reach the corals which may cause bleaching. In addition, this will increase the amounts of nutrients that enhance the growth of other reef organisms such as sponges which may outcompete the corals for space on very crowded reefs.

In addition to runoff, outflows from water treatment plants and large power plants are mainly the cause of the severe damage to coral reefs. Sewage treatment facilities greatly increase the nutrient levels which surround their outflow pipes while large power plants alter water temperatures by discharging extremely hot water into the coastal waters. And with all these factors, the basis of the continuing of the degradation of coral reefs is increasingthe size of the human population.

As the human population increases, so does the harvest of resources from the sea. Due to overfishing, the population of fish that live among the reefs have been greatly decreased in some areas of the world. The removal of large numbers of reef fish has made the ecosystems of the coral reef to become unbalanced, allowing more competitive organisms, such as algae, which were once controlled by large fish populations, to dominate the corals and fish on reefs in many regions.