By Janine Mergler of Families Magazine
The Great Barrier Reef is the world’s most extensive coral reef ecosystem. With around 3,000 individual reef systems, its entirety covers an area of 344,400 square kilometres. This article explores the 5 biggest threats to the Great Barrier Reef and what is being done to combat them.
See Also:
- A Sustainable Blue Economy: Circularity and Ocean Resources
- Circular Blue Economy: Current Practices and Future Plans
- BlueWaveID: The App That Identifies Cetaceans
- Max Romey, Ocean Plastics, and a Circular Footwear Industry
Increasing Water Temperature
The surface temperature of the Great Barrier Reef has increased by 0.8°C since the late 19th century. Water temperature in the Great Barrier Reef is linked to climate change. As greenhouse gas emissions increase, so too will the Reef’s water temperature.
Why is this a threat to the Great Barrier Reef?
Fun fact – the reef is a living entity. Coral may look like a rock garden filled with colourful plants, but it is actually made up of millions of marine invertebrates. These invertebrates have vibrantly coloured tentacles to trap food and nutrients, and they protect their soft bodies by creating a limescale exoskeleton from ocean minerals.
Coral invertebrates are not able to regulate their body temperature. They are also fixed in place, so they cannot move elsewhere when the water temperature becomes higher or lower than they can tolerate. A higher water temperature leads to stress and a phenomenon known as coral bleaching. Whilst coral can survive some instances of coral bleaching, prolonged or frequent bleaching leads to death.
If all the coral should die, over 9,000 known species will lose their home, and many species would cease to exist.
What is being done about it?
Reducing greenhouse gas emissions requires a global effort. There is no quick way to reverse the climate damage already done, so coral must adapt to survive.
Marine biologists are working to help coral adapt to warmer temperatures. Scientists have discovered that certain probiotics – good bacteria – can help coral stay healthy enough to survive periods of stress and become more resilient. The Great Barrier Reef Foundation is supporting research to determine which probiotics are best suited to each species of coral to offer the best chance of survival.
Credit: NASA/Kjell Lindgren – https://www.flickr.com/photos/nasa2explore/24150324632/
Poor Water Quality
It may be hard to believe, but agriculture, horticulture and gardening are direct threats to the Great Barrier Reef’s water quality.
How is this a problem?
Pesticides, herbicides, and fertilisers find their way into creeks, stormwater drains and rivers, eventually discharging into our oceans. This is known as land-based run-off, and when it occurs in catchments close to the reef, it can have a devastating effect on marine life.
These chemicals and nutrients affect the delicate balance of reef organisms. They can kill beneficial bacteria, cause harmful algae to bloom, and poison marine life.
Other factors effecting water quality in the reef include:
- Flood plumes – sediment from flooding reduces the amount of light available for coral to grow.
- Personal care products – chemical and plastic microbead pollution from sunscreens, deodorants, shower gels, moisturisers etc. enters the water from nearby waste treatment plants, or directly from tourists enjoying reef activities.
- Marine debris – litter in the water can trap marine life or be mistaken for food.
What is being done about it?
The Australian and Queensland governments are implementing the Reef 2050 Water Quality Improvement Plan. The Plan aims to improve land management practices with trials of more efficient fertilisers and resilient crops.
Teach kids about sustainability of the reef now to improve the reef for future generations. Choosing to use organic products, reduce plastic use, and minimise waste will have a sustained positive impact.
Crown-of-Thorns Starfish
Crown-of-thorns starfish are native to the Great Barrier Reef, and adults feed exclusively on live coral.
Why are they a problem?
Crown-of-thorns starfish usually live in small numbers feeding on small areas of coral. Every so often, conditions on the reef become optimal for the starfish population to grow and reproduce rapidly. The starfish can spread over vast areas of the reef, devouring all the coral and destroying the habitat and food supply of other marine life.
Optimal conditions for crown-of-thorns starfish occur when:
- Excess nutrients from land-based run-off provide extra nutrients for the starfish larvae to survive.
- The number of the starfish’s natural predators is reduced through over fishing or pollution.
- Sufficient live coral is available to support outbreak numbers.
What is being done about them?
The Marine Park Authority runs a Crown-of-thorns Starfish Control Program which encourages marine park users to report sightings of the starfish. Rangers and crews then conduct a culling exercise to reduce starfish numbers in the area.
The Program aims to control starfish numbers to achieve a sustainable ecological balance.
Credit: depositphotos.com
Ocean Acidification
Greenhouse gas emissions increase carbon dioxide in the atmosphere. Carbon dioxide dissolves in the ocean to form carbonic acid, which lowers the pH of the water and makes it more acidic.
Why is this a problem?
We mentioned earlier that live coral protects itself by building a limescale exoskeleton. Calcium carbonate is a main component of limescale, but it dissolves if the pH of the water drops too low. Coral is highly vulnerable to predators without its protective exoskeleton.
Certain fish species lose their ability to detect predators in more acidic waters, too. When acidic water causes a reduction in coral and certain fish, the entire food web and marine ecosystem is at risk.
What is being done about it?
The best way to reduce ocean acidification is to reduce greenhouse gas emissions, but that will take a long time. In the meantime, scientists are developing techniques to manipulate the chemistry of seawater in localised areas of the reef to restore the pH balance.
Industry
Governments often focus on economic growth through industry, and Industry is one of the biggest threats to the Great Barrier Reef.
How did industry become one of the biggest threats to the Great Barrier Reef?
Farming, construction, and mining already has a negative impact on the reef through land-based run-off, greenhouse gas emissions, and pollution. Large scale industry is frequently an international business. Raw materials and finished products are traded globally, and much of that is moved on huge cargo ships.
The majority of Queensland’s exports are shipped through ten ports located in the Great Barrier Reef World Heritage Area. As production increases, more and bigger ships are required.
Shipping has a negative impact on the Great Barrier Reef because:
- The ocean floor must be dredged to create sufficient depth for ships to pass safely through.
- Ships’ engines create underwater noise that can interfere with marine life.
- There is risk of pollution from fuels, fumes, and human waste.
What is being done about it?
The Australian and Queensland Governments’ Reef 2050 Plan continues to investigate strategies to reduce the impact of shipping on marine life, including the establishment of a national strategy to reduce vessel strike on turtles and large marine mammals, and the expansion of the designated “Particularly Sensitive Sea Area”.
What can you do to help the Great Barrier Reef?
Heavy import and export industries are not the only industry present in the Great Barrier Reef. Reef tourism contributes over $5 billion annually to the Australian economy.
As one of the Seven Wonders of the Natural World, the Great Barrier Reef attracts over 2 million visitors every year, keen to see its brilliant colours and spectacular marine life for themselves. The reef stretches 2,300km along Queensland’s coastline, from the tip of Cape York right down to Bundaberg, offering plenty to explore. Visitors to Cairns can enjoy the reef at its tropical best, whilst Airlie Beach is the perfect place from which to visit the Whitsundays and Whitehaven Beach.
Choosing the Great Barrier Reef as your next holiday destination provides immediate help by helping to sustain the industries most concerned with its conservation. To help in the long term, consider ways in which you can reduce your own carbon footprint and encourage governments to reduce their greenhouse gas emissions.
About the Author
After moving from London to Brisbane, Janine Mergler brought the Families Magazine brand to life locally in 2013 to create a sense of work/life balance while raising her son. Her tenacious, genuine approach allows her to really get to know her staff, her audience and her business partners. Janine believes in education, equality and engaging families in positive, authentic experiences.