The Great Barrier Reef
An experienced scuba diver floats above the rainbow reefs in awe of the fish that school around him. The sunlight warms the water and provides a beautiful spotlight for the marine life to play. His air bubbles drift up towards the seaweed tangled at the surface. Turtles drift through on the beginning of a lifelong journey he is lucky to catch a glimpse of. Sometimes the view is so beautiful he feels as though he is intruding. So, he attempts to be still and avoids meddling in the lives around him. He only watches as the damselfish dip in and out of hiding places, looking for refuge when larger fish loom overhead.
|
Only 20 years later, he could swear that he got lost on his usual dive and wandered away from his beloved reef. Where assorted colorful corals once painted the seascape, now lies bleached brains and dead branches. A lone clownfish skitters through, hoping for greener pastures and a better place to find food. Plastic jellyfish float around and twirl in the current. A surgeonfish hides underneath an abandoned pair of sunglasses nestled in a groove in the dying reef. Now he is sure he must have intruded. Maybe he scared all his friends away. He hopes it is not for good.
|
The Great Barrier Reef covers an area of 348,000 square kilometers on the north-east coast of Australia. Being one of the world’s most diverse and colorful environments, this reef system holds huge scientific interest. This ecosystem provides homes for 400 types of coral, 1,500 species of fish, 4,000 types of mollusk, 240 species of birds, plus a great diversity of sponges, anemones, marine worms, and crustaceans. Additionally, this environment houses organisms like the dugong and large green turtle, both of which are threatened with extinction.
Aside from the striking biodiversity happening below sea level, the Great Barrier Reef is just as impressive above the waves. The Whitsunday Islands provide a glorious vista of green vegetated landscape that contrasts the spotty sandy beaches that spread over these caerulean waters. Furthermore, enormous mangrove forests extend the Hinchinbrook Channel, running alongside the lush, cloud-covered rainforest gullies that make up Hinchinbrook Island.
The reef, made up of 2,500 individual reefs of all different shapes and sizes, includes a wide array of cross-shelf diversity, reaching all the way from the low water mark to 250 kilometers offshore. This allows for extensive shallow inshore areas, mid-shelf and outer reefs, and areas past the continental shelf in oceanic waters at over 2,000 meters deep. In fact, almost a third of the Great Barrier Reef is beyond the seaward edge of the shallow reefs, where one can find continental slopes, deep oceanic waters, and abyssal plains.
In addition to reefs, over 900 islands help make up the Great Barrier Reef, providing above ground landscape like sandy cays and even large continental islands rising over 1,100 meters above sea level. Lying on some of these cays, are crucially important breeding colonies for marine turtles and seabirds. Specifically, Raine Island is the world’s largest green turtle breeding area. With vegetation being established on cays and continental islands, the importance of birds like the Pied Imperial Pigeon and its role in seed dispersal and plant colonization is exemplified.
Inter-reefal areas also play an important role ecologically. Half the world’s diversity of mangroves and seagrass species is found here. These shallow marine areas provide major feeding grounds for at least 30 species of whale and dolphin, holding significant importance for the endangered dugong species.
Because of this vastness, the Great Barrier Reef is one of the only few living structures visible from space. From above, one can capture the extensive myriad of reefs, coral cays, and islands.
Beneath the rolling waves, lies an abundance of spectacular coral assemblages formed by foundational hard and soft corals accompanied by thousands of species of reef fish. This kind of diverse environment produces impressive natural phenomena like spawning aggregations for local fish species, nesting turtles, the annual coral spawning, and migrating whales.
In the photograph above, rays of sunlight trickle through the ocean surface, illuminating the remarkable variety of life teeming on a tiny portion of this extensive reef. Stunning, orange Garibaldi damselfish travel in schools, wandering about the rainbow-colored reef. One in particular, marked with a black spot, drifts overtop an easily identifiable yellow brain coral. Stony corals like Acroporidae and Merulinidae can also be seen scattered around the image, providing shelter and food for fish like the black and white Chromis iomelas. In return for housing and nutrition, fish provide protection from some of the coral’s natural enemies, such as seaweeds, creating an incredible mutualistic relationship.
Long before this photo was taken, when glaciers were still abundant, sea levels dropped, and exposed flat-topped reefs made of eroded limestone. Huge rivers wandered between these uncovered reefs, carving out the present-day mosaic. Then, during interglacial time periods, sea levels rose and helped form the coral cays and continental islands that are still seen today. This reef has been uncovered and flooded by at least four glacial and interglacial cycles over the past 15,000 years. The history of this area’s outstanding evolution can be seen in the cores of some of the oldest massive corals. Other signs of evolution can be found in the large beds of Halimeda algae that represent active calcification and accretion that has been happening over thousands of years.
Since this photo was taken, the Great Barrier Reef has seen a pretty dramatic downfall, resulting in dying coral and vanishing wildlife. This decline is due to natural pressures like crown-of-thorns starfish outbreaks and human pressures like tourism, coastal developments, pollution, and climate change. Luckily, because the Great Barrier Reef is so extensive, most habitats or species groups are able to recover from disturbances and withstand some of these ongoing pressures. However, if these problems continue to grow and increase their pressure on the reefs, the damage could eventually reach a point of no return.
Climate change is currently the largest threat to the Great Barrier Reef and all other reefs around the globe. Climate change not only increases the ocean’s temperatures but also increases the ocean’s acidity levels. These huge challenges are creating severe knock-on effects and jeopardizing the Great Barrier Reef’s survival. Sea surface temperatures in areas off the coastline of Queensland have risen 0.4–0.5 °C since the late 19th century. This increase in temperature put the reefs at greater risk of heat stress and mass coral bleaching. This in turn decreases the ability of the corals to build skeletons, which provide the vast reef marine life with key habitats. Rising temperatures also cause sea levels to rise, which can lead to coastal erosion and decreased health of tidal habitats. Additionally, the oceans have absorbed nearly 30% of the excess carbon dioxide human activity has pushed into the atmosphere since the late 18th century. This extra carbon dioxide affects the ocean’s chemistry, causing the ocean to become more acidic by decreasing the water’s pH levels. Lastly, climate change has increased the frequency of severe weather events like cyclones. These new record rainfall levels and storms can destroy reef structures and send an influx of freshwater and sediment further out from the coast.
Declining coastal water quality is another significant threat to the long-term health and resilience of the Great Barrier Reef. Land-based run-off leads to increasing levels of sediment, nutrients, and contaminants in coastal waters. These factors greatly decrease the water quality, causing a serious threat to the coral reefs and the organisms that inhabit them. The Great Barrier Reef specifically receives run-off from 35 major catchments that drain into 424,000 square kilometers of coastal Queensland waters. Most sediment that flows into the reefs comes from major pastoral area catchments in Burdekin, Herbert, and Fitzroy Rivers. The more excess sediment and nutrients that enter the water, the more algal growth, smothered corals, and build-up of pollutants in marine species. It can also lead to a large reduction in the amount of sunlight getting through to the coral reef systems.
Nutrient run-off is also connected to severe outbreaks of crown-of-thorns starfish. This species of starfish is naturally occurring in this area of the world and is an important part of the ecosystem. Normally, crown-of-thorns starfish tend to eat faster growing corals, giving slower growing species a chance to claim some space of their own and furthermore, enhance the reef system’s coral diversity. However, when these spiky marine creature’s numbers rise outside the normal range, it can cause detrimental damage to the precious reefs. Excess nutrients from run-off and overfishing of this marine invertebrate’s natural predators are large factors influencing outbreaks of crown-of-thorns starfish. In a 2012 study, the Australian Institute of Marine Science found that these starfish, in addition to tropical cyclones, were the leading cause of coral loss in the Great Barrier Reef over the last 27 years.
While Queensland continues to develop and grow, the coast and islands running alongside the reefs follow suit. Growing needs for agriculture, mining, urban progress, port development, and aquaculture can have detrimental effects on the coral reefs just offshore. Specifically, port development has been a key factor in coastal reclamation, which involves infilling areas of the ocean along the coastline and creating artificial barriers that affect water flow.
In order to manage such an expansive and globally important world heritage property, many policies and agencies were put in place. The Great Barrier Reef Marine Park Authority is an independent government agency in Australia that is responsible for the protection and management of the Great Barrier Reef Marine Park. In 1975, the Great Barrier Reef Marine Park Act was passed and then later amended in 2007 and 2008. This act now provides long-term protection and conservation for this region. Moreover, the Marine Parks Act of 2004 established that Queensland, Australia is responsible for the management of the Great Barrier Reef Marine Park as well. This act covers the area between the low and high-water mark, as well as many of the islands included in the reef system. The Federal Environmental Protection and Biodiversity Conservation Act of 1999 is a foundational outline for protecting the World Heritage values and requires any developmental proposals to undergo rigorous environmental impact assessment processes designed to mitigate any significant impacts.
Other significant programs that allow for more protection of the reef include the comprehensive Great Barrier Reef Outlook Report, the Reef Water Quality Protection Plan, the Great Barrier Reef Climate Change Action Plan, and the Reef Guardians Stewardship Programs.
These overlapping jurisdictions lead to the significance of complementary management and legislation from both governments in regard to conservation of the Great Barrier Reef. Strong cooperative partnerships now exist between not only the Australian Government and Queensland Government, but also with the commercial and recreational industries of Australia.
Long-term challenges for the Great Barrier Reef are detailed in the 2009 Outlook Report, which writes climate change as the leading issue. This report also identified loss of coastal habitats from coastal development, continued declining water quality from land-based sources, and illegal fishing and poaching as the other priority issues requiring government attention in order to stop the decline of this bionetwork. Issues that emerged after the 2009 report include new port expansions encroaching on reef habitat space, increases in shipping activity, population growth, increases in pollution, and extreme weather events like cyclones and floods.
While the Great Barrier Reef is already a robust ecosystem, humans can help build its resilience by working to improve water quality, reduce the loss of coastal habitats, and educate the population about proper fishing practices. This will give the reef a better chance of recovering from the previous damage and adapting to the threats ahead
Aside from the striking biodiversity happening below sea level, the Great Barrier Reef is just as impressive above the waves. The Whitsunday Islands provide a glorious vista of green vegetated landscape that contrasts the spotty sandy beaches that spread over these caerulean waters. Furthermore, enormous mangrove forests extend the Hinchinbrook Channel, running alongside the lush, cloud-covered rainforest gullies that make up Hinchinbrook Island.
The reef, made up of 2,500 individual reefs of all different shapes and sizes, includes a wide array of cross-shelf diversity, reaching all the way from the low water mark to 250 kilometers offshore. This allows for extensive shallow inshore areas, mid-shelf and outer reefs, and areas past the continental shelf in oceanic waters at over 2,000 meters deep. In fact, almost a third of the Great Barrier Reef is beyond the seaward edge of the shallow reefs, where one can find continental slopes, deep oceanic waters, and abyssal plains.
In addition to reefs, over 900 islands help make up the Great Barrier Reef, providing above ground landscape like sandy cays and even large continental islands rising over 1,100 meters above sea level. Lying on some of these cays, are crucially important breeding colonies for marine turtles and seabirds. Specifically, Raine Island is the world’s largest green turtle breeding area. With vegetation being established on cays and continental islands, the importance of birds like the Pied Imperial Pigeon and its role in seed dispersal and plant colonization is exemplified.
Inter-reefal areas also play an important role ecologically. Half the world’s diversity of mangroves and seagrass species is found here. These shallow marine areas provide major feeding grounds for at least 30 species of whale and dolphin, holding significant importance for the endangered dugong species.
Because of this vastness, the Great Barrier Reef is one of the only few living structures visible from space. From above, one can capture the extensive myriad of reefs, coral cays, and islands.
Beneath the rolling waves, lies an abundance of spectacular coral assemblages formed by foundational hard and soft corals accompanied by thousands of species of reef fish. This kind of diverse environment produces impressive natural phenomena like spawning aggregations for local fish species, nesting turtles, the annual coral spawning, and migrating whales.
In the photograph above, rays of sunlight trickle through the ocean surface, illuminating the remarkable variety of life teeming on a tiny portion of this extensive reef. Stunning, orange Garibaldi damselfish travel in schools, wandering about the rainbow-colored reef. One in particular, marked with a black spot, drifts overtop an easily identifiable yellow brain coral. Stony corals like Acroporidae and Merulinidae can also be seen scattered around the image, providing shelter and food for fish like the black and white Chromis iomelas. In return for housing and nutrition, fish provide protection from some of the coral’s natural enemies, such as seaweeds, creating an incredible mutualistic relationship.
Long before this photo was taken, when glaciers were still abundant, sea levels dropped, and exposed flat-topped reefs made of eroded limestone. Huge rivers wandered between these uncovered reefs, carving out the present-day mosaic. Then, during interglacial time periods, sea levels rose and helped form the coral cays and continental islands that are still seen today. This reef has been uncovered and flooded by at least four glacial and interglacial cycles over the past 15,000 years. The history of this area’s outstanding evolution can be seen in the cores of some of the oldest massive corals. Other signs of evolution can be found in the large beds of Halimeda algae that represent active calcification and accretion that has been happening over thousands of years.
Since this photo was taken, the Great Barrier Reef has seen a pretty dramatic downfall, resulting in dying coral and vanishing wildlife. This decline is due to natural pressures like crown-of-thorns starfish outbreaks and human pressures like tourism, coastal developments, pollution, and climate change. Luckily, because the Great Barrier Reef is so extensive, most habitats or species groups are able to recover from disturbances and withstand some of these ongoing pressures. However, if these problems continue to grow and increase their pressure on the reefs, the damage could eventually reach a point of no return.
Climate change is currently the largest threat to the Great Barrier Reef and all other reefs around the globe. Climate change not only increases the ocean’s temperatures but also increases the ocean’s acidity levels. These huge challenges are creating severe knock-on effects and jeopardizing the Great Barrier Reef’s survival. Sea surface temperatures in areas off the coastline of Queensland have risen 0.4–0.5 °C since the late 19th century. This increase in temperature put the reefs at greater risk of heat stress and mass coral bleaching. This in turn decreases the ability of the corals to build skeletons, which provide the vast reef marine life with key habitats. Rising temperatures also cause sea levels to rise, which can lead to coastal erosion and decreased health of tidal habitats. Additionally, the oceans have absorbed nearly 30% of the excess carbon dioxide human activity has pushed into the atmosphere since the late 18th century. This extra carbon dioxide affects the ocean’s chemistry, causing the ocean to become more acidic by decreasing the water’s pH levels. Lastly, climate change has increased the frequency of severe weather events like cyclones. These new record rainfall levels and storms can destroy reef structures and send an influx of freshwater and sediment further out from the coast.
Declining coastal water quality is another significant threat to the long-term health and resilience of the Great Barrier Reef. Land-based run-off leads to increasing levels of sediment, nutrients, and contaminants in coastal waters. These factors greatly decrease the water quality, causing a serious threat to the coral reefs and the organisms that inhabit them. The Great Barrier Reef specifically receives run-off from 35 major catchments that drain into 424,000 square kilometers of coastal Queensland waters. Most sediment that flows into the reefs comes from major pastoral area catchments in Burdekin, Herbert, and Fitzroy Rivers. The more excess sediment and nutrients that enter the water, the more algal growth, smothered corals, and build-up of pollutants in marine species. It can also lead to a large reduction in the amount of sunlight getting through to the coral reef systems.
Nutrient run-off is also connected to severe outbreaks of crown-of-thorns starfish. This species of starfish is naturally occurring in this area of the world and is an important part of the ecosystem. Normally, crown-of-thorns starfish tend to eat faster growing corals, giving slower growing species a chance to claim some space of their own and furthermore, enhance the reef system’s coral diversity. However, when these spiky marine creature’s numbers rise outside the normal range, it can cause detrimental damage to the precious reefs. Excess nutrients from run-off and overfishing of this marine invertebrate’s natural predators are large factors influencing outbreaks of crown-of-thorns starfish. In a 2012 study, the Australian Institute of Marine Science found that these starfish, in addition to tropical cyclones, were the leading cause of coral loss in the Great Barrier Reef over the last 27 years.
While Queensland continues to develop and grow, the coast and islands running alongside the reefs follow suit. Growing needs for agriculture, mining, urban progress, port development, and aquaculture can have detrimental effects on the coral reefs just offshore. Specifically, port development has been a key factor in coastal reclamation, which involves infilling areas of the ocean along the coastline and creating artificial barriers that affect water flow.
In order to manage such an expansive and globally important world heritage property, many policies and agencies were put in place. The Great Barrier Reef Marine Park Authority is an independent government agency in Australia that is responsible for the protection and management of the Great Barrier Reef Marine Park. In 1975, the Great Barrier Reef Marine Park Act was passed and then later amended in 2007 and 2008. This act now provides long-term protection and conservation for this region. Moreover, the Marine Parks Act of 2004 established that Queensland, Australia is responsible for the management of the Great Barrier Reef Marine Park as well. This act covers the area between the low and high-water mark, as well as many of the islands included in the reef system. The Federal Environmental Protection and Biodiversity Conservation Act of 1999 is a foundational outline for protecting the World Heritage values and requires any developmental proposals to undergo rigorous environmental impact assessment processes designed to mitigate any significant impacts.
Other significant programs that allow for more protection of the reef include the comprehensive Great Barrier Reef Outlook Report, the Reef Water Quality Protection Plan, the Great Barrier Reef Climate Change Action Plan, and the Reef Guardians Stewardship Programs.
These overlapping jurisdictions lead to the significance of complementary management and legislation from both governments in regard to conservation of the Great Barrier Reef. Strong cooperative partnerships now exist between not only the Australian Government and Queensland Government, but also with the commercial and recreational industries of Australia.
Long-term challenges for the Great Barrier Reef are detailed in the 2009 Outlook Report, which writes climate change as the leading issue. This report also identified loss of coastal habitats from coastal development, continued declining water quality from land-based sources, and illegal fishing and poaching as the other priority issues requiring government attention in order to stop the decline of this bionetwork. Issues that emerged after the 2009 report include new port expansions encroaching on reef habitat space, increases in shipping activity, population growth, increases in pollution, and extreme weather events like cyclones and floods.
While the Great Barrier Reef is already a robust ecosystem, humans can help build its resilience by working to improve water quality, reduce the loss of coastal habitats, and educate the population about proper fishing practices. This will give the reef a better chance of recovering from the previous damage and adapting to the threats ahead
References
UNESCO World Heritage Centre. “Great Barrier Reef.” UNESCO, United Nations Educational, Scientific, and Cultural Organization, whc.unesco.org/en/list/154/.
“Threats to the Reef.” Great Barrier Reef Foundation, 2020 Great Barrier Reef Foundation, www.barrierreef.org/the-reef/threats.
“Threats to the Reef.” Great Barrier Reef Foundation, 2020 Great Barrier Reef Foundation, www.barrierreef.org/the-reef/threats.