chapter 3
Why reefs are declining
Coral reefs have survived tens of thousands of years of natural change, but many of them may not be able to survive the havoc wrought by humankind.
Roughly one-quarter of coral reefs worldwide are already considered damaged beyond repair, with another two-thirds under serious threat.
threats
Major threats to coral reefs and their habitats include:
Destructive fishing practices: These include cyanide fishing, blast or dynamite fishing, bottom trawling, and muro-ami (banging on the reef with sticks). Bottom-trawling is one of the greatest threats to cold-water coral reefs.
Overfishing: This affects the ecological balance of coral reef communities, warping the food chain and causing effects far beyond the directly overfished population.
Careless tourism: Careless boating, diving, snorkeling, and fishing happens around the world, with people touching reefs, stirring up sediment, collecting coral, and dropping anchors on reefs. Some tourist resorts and infrastructure have been built directly on top of reefs, and some resorts empty their sewage or other wastes directly into water surrounding coral reefs.
Pollution: Urban and industrial waste, sewage, agrochemicals, and oil pollution are poisoning reefs. These toxins are dumped directly into the ocean or carried by river systems from sources upstream. Some pollutants, such as sewage and runoff from farming, increase the level of nitrogen in seawater, causing an overgrowth of algae, which 'smothers' reefs by cutting off their sunlight.
Sedimentation: Erosion caused by construction (both along coasts and inland), mining, logging, and farming is leading to increased sediment in rivers. This ends up in the ocean, where it can 'smother' corals by depriving them of the light needed to survive. The destruction of mangrove forests, which normally trap large amounts of sediment, is exacerbating the problem.
Coral mining: Live coral is removed from reefs for use as bricks, road-fill, or cement for new buildings. Corals are also sold as souvenirs to tourists and to exporters who don't know or don't care about the longer term damage done, and harvested for the live rock trade.
Climate change: Corals cannot survive if the water temperature is too high. Global warming has already led to increased levels of coral bleaching, and this is predicted to increase in frequency and severity in the coming decades. Such bleaching events may be the final nail in the coffin for already stressed coral reefs and reef ecosystems.
Coral reefs are fragile ecosystems that are very vulnerable to changes in ocean temperature. Their populations are rapidly declining. Global warming is one of the factors responsible for this.
Coral extinctions in the past
To find out how coral reefs might respond to climate change we can look at what has happened to them in the past.
Museum scientist Ken Johnson studies coral reefs in the Late Cenozoic era, between 30 million years ago and the present day. In this time, there were 2 occasions when many reef-corals became extinct in the Caribbean.
Different types of extinction
Reefs are made up of a number of different species of coral. In the extinction that took place 1 million years ago, coral reefs flourished but the number of species they contained dropped.
In the extinction that took place in the Oligocene period, 24 million years ago, both the overall area of coral reef and the number of species declined.
There are several theories about the cause of these coral extinctions and changes in reef growth. Some of them are based on changes in climatic conditions in the oceans.
Effects of the Central American isthmus on the reefs
Until about 4 million years ago, the Pacific and Atlantic oceans were connected, as the isthmus of Central America did not exist.
Many scientists think that the Oligocene extinction 24 million years ago was caused by increased amounts of water flowing from the Pacific into the Atlantic at that time.
Water from the Eastern Pacific is rich in nutrients that have been brought up to the surface from the deep sea. Coral reefs thrive in water with low nutrients, but they do not usually survive in nutrient-rich waters.
An increased flow of Pacific water in the Caribbean during the Oligocene would have caused the death of corals and coral reefs that were adapted to life in nutrient-poor habitats.
In the 10s of millions of years following this demise, new kinds of corals evolved that were able to live under the changed conditions. However, they were rarely able to build extensive coral reef systems.
The reefs after the isthmus closed
Once the Central American isthmus closed, the nutrient supply was cut off and reefs could once again develop. But this change in environment also caused the extinction of over half of the coral species living in the region.
Modern Caribbean reefs are constructed by relatively few species that evolved prior to the extinction. These species were not able to become dominant until the isthmus closed and new environmental conditions were established.
Coral reefs today
As the Earth warms again, coral reefs are struggling once more. Worldwide, reefs are currently declining more quickly than rainforests are being cut down. As with the Oligocene extinction, once they are gone they will be gone for a long time and, even if they recover, they will surely look very different to living reefs.
Extinctions in the sea
Extinctions of marine organisms are not as well-documented as extinctions of land-living animals. But that does not make them less important.
The oceans are home to 230,000 known kinds of life, but scientists think that as many as 80% of species on the planet may yet be undiscovered, the majority of which live in the ocean. Until we identify more of these species, we will not know how many of them are becoming extinct due to global warming.
Impacts on humans
The extinction of coral reefs would have a knock-on effect on species that depend on them. Fish that live on coral reefs will be threatened and fisheries on the reefs will be damaged.
Thousands of tourists visit coral reefs every year to go diving and snorkelling, and so tourism has become an important part of the local economy in some regions. Without the coral reefs, this part of the economy would collapse.
The loss of both fisheries and tourism could leave people living near coral reefs without a livelihood
Future of the reefs
Many of the changes seen in coral communities since 1980 have been natural and cyclical, says Done.
He said that crown of thorns starfish were a normal part of coral reefs, but the last 60 years had shown they tended to 'outbreak' in 15-year cycles.
While the reef has survived crown of thorn outbreaks, the unknowns of future climate change mean that it's uncertain how it will fair in the 21st century.
"We don't think the Great Barrier Reef will be at the upper end of the global temperature average. In fact, we think it will be slightly lower than the global average," says Wachenfeld, "but it will still be a big factor in uncertainty for the future of the Great Barrier Reef."
In the meantime, Wachenfeld says that all scientists can do is aim to keep the reef as healthy as possible.
"A lot of what we're doing is to make the Great Barrier Reef healthier and more resilient, to help it get through the impact of climate change."
ch of the carbon dioxide that enters the atmosphere dissolves into the ocean. In fact, the oceans have absorbed about 1/3 of the carbon dioxide produced from human activities since 1800 and about 1/2 of the carbon dioxide produced by burning fossil fuels (Sabine et al. 2004). As carbon dioxide in the ocean increases, ocean pH decreases or becomes more acidic. This is called ocean acidification.
With ocean acidification, corals cannot absorb the calcium carbonate they need to maintain their skeletons and the stony skeletons that support corals and reefs will dissolve. Already, ocean acidification has lowered the pH of the ocean by about 0.11 units (SCOR 2009). Moving the ocean's pH from 8.179 to a current pH of 8.069, which means the ocean is about 30% more acidic now than it was in 1751 (SCOR 2009). If nothing is done to reduce carbon dioxide emissions into the atmosphere, ocean acidification will increase and more and more corals will be damaged or destroyed.
Coral Reefs are huge Scuba Diving attractions. Brilliant colors like pinks, purples, yellows and reds stand out against the hues of blue. Shoals of brightly colored fish dart in and out of the different type of coral, sea anemones, sea urchins and sponges.These ecosystems are the forest of the Oceans and 25% of all marine life reside in these reefs. The rich colorful environment of coral reefs, along with it’s wealth of marine life make it the most popular type of diving destination to explore and discover. Here’s a take of the most stunning Coral Reefs and Reef areas in the World-
Chapter 4
Experiences and tourist of the reefs
Five ways to explore the Great Barrier Reef:
Whitsunday Islands, QLD
1. From the top, island hop
Party in Airlie Beach, hit the water sports on Hamilton, honeymoon on luxurious Hayman or just chill out on the soft, white sand of Whitehaven Beach on Whitsunday Island. For accommodation, you’ll find everything from five-star resorts to the back-to-nature simplicity of tents in natural settings. You can go castaway on many of Great Barrier Reef’s lush island national parks. There’s Green and Fitzroy islands near Cairns, and Dunk, Bedarra, Hinchinbrook and Orpheus islands further south. Head to Hayman, Heron and Lizard Islands for superior resorts and diving.
Great Barrier Reef, QLD
2. With flippers and a wetsuit
Check out the technicolour coral and marine life through a glass-bottomed boat from coastal hubs such as Cairns, Port Douglas, Townsville, Bundaberg, Rockhampton, Mackay, Mission Beach and Airlie Beach. Or experience the reef’s smooth seas, deep drop offs, underwater tunnels and caves with a dive school or day trip operator. Snorkel or dive the edge of the continental shelf at Agincourt Reef from Cairns, explore the SS Yongala shipwreck from Townsville and Magnetic Island and the Llewellyn shipwreck from Mackay. See sea stars, crabs corals, molluscs at Fitzroy, Capricorn and Bunker Reefs near Gladstone. Or kick through vivid coral canyons and past marine turtles near Lady Elliot and Lady Musgrave Islands. In the Whitsundays, the warm clear water and psychedelic coral reefs are just a day trip from your Airlie Beach or island resort.
Great Barrier Reef, QLD
3. With wind in your sails
Set sail from Port Douglas for Low Isles, a secluded island jewel discovered by Captain Cook in 1770. Or charter a boat from Hamilton Island or Airlie Beach and coast through the turquoise water of the Whitsundays. Anchor overnight at picturesque moorings such as Whitehaven Beach, Cid Harbour and Butterfly Bay and visit the reefs of Black, Langford and Bird Island along the way. Stop for resort relaxation on Daydream, Hamilton or Long Islands. You can also take a bareboat from Cairns or Airlie Beach to the outer Greater Barrier Reef. Learn to sail with fully qualified staff or take on a skipper until you feel confident enough to take the wheel. You can also charter vessels from Maxi Racers to catamarans, complete with a trained crew. Or meet new people on a fully crewed overnight charter.
Daintree National Park, QLD
4. Smelling rainforest air
Trek, camp and commune with nature in the region’s national parks, which stretch from Cape York to the lush Whitsunday islands. Cruise down the Daintree River and visit Mossman Gorge in the Daintree Rainforest. Spot nocturnal wildlife and swoon at Bloomfield Falls when you reach Cape Tribulation, where the forest plunges literally to the reef. Bushwalk through gorges and subtropical and tropical rainforests in Eungella National Park, set in the mist-shrouded mountains west of Mackay. Picnic under swamp mahoganies and red gums and take in scenic lookout and rich bird and wildlife. In the Whitsunday National Park, you can walk from Tongue Bay on Whitsunday Island for great views. Or see precious rock art by the Ngaro people at Nara Inlet, Hook Island. Camp, wake to birdsong, swim on deserted beaches and smell fragrant rainforest air on Hook, Long, Cid, North and South Molle Islands to name a few.
Whitehaven Beach, QLD
5. With your adrenalin pumping
Soar over the Daintree Rainforest and the Great Barrier Reef on a scenic helicopter flight to Green Island. Spectacular Heart Reef is located on Hardy Reef in the Whitsundays and is best experienced from a seaplane or helicopter. Combine a snorkelling day trip to the reef from Cairns with a hot air balloon ride over the Atherton Tablelands. Take a luxury catamaran from Cairns and Port Douglas to the outer Great Barrier Reef. Or drift between Cairns and Townsville on a luxury three-day cruise. Stay on Airlie Beach or at a resort on Hamilton or Daydream Island and try your hand at parasailing, boating, bushwalking, sea-kayaking, fishing, snorkelling and more.
Mission Beach is a relaxed beachfront town, located mid-way between Cairns and Townsville on the Queensland coast. Overlooking the cobalt waters of the Coral Sea, Mission Beach has more than 14 kilometres of magnificent golden sandy beaches. Here two World Heritage areas, the Great Barrier Reef and Wet Tropics Rainforest form a natural environment like nowhere else on earth. Mission Beach is a gateway to the Great Barrier Reef and a perfect base for visiting nearby Dunk, Bedarra and Hinchinbrook islands. At Mission Beach, you can find either extreme adventure or an indulgent tropical escape.
The coastal village of Airlie Beach is a vibrant town filled with palm-fringed beaches, waterfront parks and alfresco dining restaurants. You are sure to instantly warm to its bohemian charm and carefree and relaxed attitude. Airlie Beach is also the gateway to the Whitsundays, the 74 pristine islands in the north of Queensland’s Great Barrier Reef where you can visit luxurious island resorts and sip cocktails by the pool, bask in the sun or relax in a spa. Queensland’s warm, tropical climate means that winters at Airlie Beach are very mild and perfect for enjoying water activities all year round.
Just a 20 minute ferry ride off the coast from Townsville, Magnetic Island's relaxed tropical lifestyle, quiet secluded beaches, unspoilt nature, abundant wildlife and easy access to the Great Barrier Reef, make it an ideal place for a day trip or longer stay.
Hervey Bay, around 300 kilometres north of Brisbane, is an aquatic paradise and one of the best places in Australia to experience nature in the wild. The safe, sheltered waters of Hervey Bay make it ideal for year round water-sports from swimming, snorkelling and scuba diving to sailing and fishing.
The Whitsunday Islands is a group of 74 islands bordered by the Great Barrier Reef World Heritage Area and the sheltered waters of the Coral Sea. With palm-fringed secluded white sand beaches surrounded by clear blue waters, the Whitsunday Islands are the epitome of a tropical paradise.
The marine tourism industry is a major contributor to the local and Australian economy generating over $4.228 billion per annum in 2003. It is the largest commercial activity in the Great Barrier Reef region, playing an important role in presenting the World Heritage listed Great Barrier Reef Marine Park to a wide range of visitors.
For many visitors to coastal Queensland, the tourism fleet is their primary means of experiencing the Great Barrier Reef. There are approximately 820 operators and 1500 vessels operating in the Marine Park.
There are a diverse range of tourism operations in the Great Barrier Reef including day tours, overnight and extended tours, snorkelling, scuba diving and fishing charters, long range roving tours, aircraft or helicopter tours, bare boats (self-sail), glass-bottomed boat viewing, semi-submersibles and educational trips, cruise ships, beach hire and water sports, passenger ferries, whale watching and swimming with dolphins.
Mention New Caledonia to most people and the first reaction seems to be "expensive". However, on a recent trip there, not only did I discover that this isn't true, but for the diving and underwater enthusiast this is one of the most unique and overlooked places in the South Pacific. There aren't too many places where you can be diving or snorkeling a pristine World Heritage reef site less than thirty minutes from a major city but that's what you'll find in New Caledonia.
And pristine is a bit of an understatement. The islands of New Caledonia are surrounded by the largest lagoon in the world (24,000 square km), and the second largest barrier reef (at 1600km it's only about 200km shorter than the Great Barrier Reef). The lagoon is of such unique natural beauty that in 2008 it was given UNESCO World Heritage status. New Caledonia's main island of Grande Terre was, like New Zealand, one of the early land masses to break away from the Gondwana super-continent some 250 million years ago and evolve it's own unique flora and fauna in isolation. As a result, a vast number of the marine species in the lagoon are not found anywhere else on the planet. And the diversity is staggering; there are more than 2000 species of fish alone, with more being discovered all the time.
The other remarkable thing about New Caledonia's lagoon is - there's virtually nobody there! Tourism is surprisingly underdeveloped, with most visitors coming from France rather than Zealand or Australia. New Caledonia's wealth largely from its connections with France (it's a French province) and from large-scale mining on the main island so there is less reliance on tourism than in other parts of the South Pacific. This has created a unique culture blending French and Pacific, without an overtly touristy feel.
A good example can be found in Bonaire, a small Caribbean island. Bonaire earns about USD $23 million annually from coral reef activities, yet managing its marine park costs less than $1 million per year (Talbot F., and C. Wilkinson, 2001, Coral Reefs, Mangroves and Seagrasses: A Sourcebook for Managers). The variety of marine life and protected beaches supported by coral reefs provide an inviting setting for sightseers, sunbathers, snorkelers, and scuba divers. In fact, there are more than 8.5 million certified scuba divers in the United States who spend money on dive vacations each year. In 1997, the State of Florida earned USD $1.6 billion from coral reef and beach-related tourism. For residents of coral reef areas who depend on income from tourism, reef destruction creates a significant loss of employment in the tourism, marine recreation, and sport fishing industries.
Our dives in the Chesterfield Reefs near New Caledonia have been full of surprises. Sometimes it is hard to tell who is more surprised, us or the fish. Every time we jump in the water, we are immediately surrounded by a swarm of curious reef sharks.
Video: Crittercam POV – “Swim” with Gray Reef Sharks
It seems as though they don’t know what to make of these strange creatures and after a few minutes they conclude that we are neither predator nor prey and go about their business. However they always make an occasional drive-by just to let us know they are there and in charge of the reef.
Ask about the weather conditions. Poor visibility, strong winds & surge from waves reduce safe interaction at the reef.
Remember that even the lightest touch with hands, fins or other dive and snorkel equipment can damage sensitive coral polyps, the small living animals that make up the hard and soft corals at the reef.
Snorkelers should wear buoyancy control or snorkel vests to allow gear adjustments without standing on the coral.
Avoid contact with the ocean bottom; properly weighted divers should practice proper buoyancy control. Sandy areas that appear barren may support new growth if left undisturbed.
Please don't feed the fish; it destroys their natural feeding habits, and avoids any potential injury to you or the marine life.
