The process of coral bleaching appears horrifying. Imagine an entire plain of multicoloured coral turning ghostly white all at once. According to the National Geographic (2010), the Caribbean has lost around 90 percent of its coral reefs, with half of all the corals lost due to bleaching (National Oceanic and Atmospheric Administration, 2014).

“When corals are stressed by changes in conditions such as temperature, light, or nutrients, they expel the symbiotic algae living in their tissues, causing them to turn completely white.”

– National Oceanic and Atmospheric Administration, National Ocean Service, ‘What is coral bleaching?’ –

The actual process of bleaching, however alarming in the way it makes coral change so drastically, does not actually kill the coral, as the definition by NOAA above states.

Coral bleaching occurs naturally when environmental conditions change, such as an increase in water temperatures (National Geographic, 2010). Like an aircraft forced to dump excess weight in an emergency, coral polyps evacuate the symbiotic zooxanthellae that live inside them. The measure does seem extreme, but there is evidence to suggest that bleaching could be a sly way of ensuring the coral’s own survival in the long run: by expelling algae that will not be able to withstand whatever environmental changes that elicited the bleaching, the coral make room for algae that could be more hardy than their previous zooxanthellae residents (National Geographic, 2010). Although the process is geared to help the coral survive, it it does make the coral more vulnerable to perishing (NOAA, 2014), along with ridding it of the colourful, life-giving zooxanthellae that reside in the coral polyps and provide energy for the coral through photosynthesis.

With human-driven climate change showing no signs of stopping, it is expected that coral bleaching will continue at an increasingly unhealthy rate. And to make matters worse for the coral of the Great Barrier Reef and other reefs around the world, another threat looms large: the crown of thorns starfish.

The menacing-looking crown of thorns starfish (or COTS, for short), unlike coral bleaching, really is as scary as it looks, and it is obvious from the first glance how the COTS got its name. The COTS is a large species of starfish, often reaching sizes of up to a full metre across, armed with anything from 7 to 23 arms bristling with venomous spines.

The COTS also has very few natural predators once it has reached maturity (although it probably has some of the weirdest predators, such as the Starry Pufferfish and the Triton’s Trumpet snail, seen devouring a COTS here). COTS larva, on the other hand, are more vulnerable to being consumed by a wider range of aquatic life, anything from crustaceans to fish (ARKive, n.d.).

Seemingly to counter this, female COTS can carry up to 60 million eggs at once (ARKive, n.d.). Multiple starfish also coordinate their spawning (just like coral do) to increase reproductive success. COTS populations can also see sudden growth spurts known as outbreaks. The sheer number of eggs one female carries means that even small populations of starfish can quickly repopulate and far exceed their previous numbers and spells disaster for coral.  (ARKive, n.d.)

COTS outbreaks have been naturally occurring on the Great Barrier Reef every so often (Great Barrier Reef Marine Park Authority, n.d.). However, once again due to human-related factors, a natural process now runs rampant and out of control. As with eutrophication (discussed in the post immediately prior), COTS outbreaks are affected by nutrients in the water. A study on the decline of coral cover in the Great Barrier Reef conducted by De’ath, Fabricius, Sweatman and Puotinen (2012) states that “water quality affects the frequency of COTS outbreaks in the central and southern GBR (Great Barrier Reef)”. What these scientists found is that nutrient-rich waters facilitated the growth of phytoplankton, which the larva of COTS feed and thrive on. Coupled with the already impressive reproductive capabilities of the starfish and the increasing frequency of outbreaks (De’ath et al., 2012), and it is clear that human activity is worsening the situation for the Reef.

The featured image you see just above is that of Airlie Beach, Queensland. Voted 34th in a lineup of the 100 Best Towns in Australia by Australian Traveller in 2009, the exclusive town, home to just over one thousand permanent residents, lives and breathes tourism, much like the rest of the Great Barrier Reef.

Tourism on natural sites such as the Great Barrier Reef is excellent in a variety of ways. First and foremost, it brings the curious tourist into direct and intimate contact with nature. Such close contact, whether it is with a gigantic humpback whale on the Great Barrier Reef, or a smaller-scale encounter with some fish swimming near shore, elicits a sense of awe and closeness with nature in humans that cannot be felt any other way.

Beyond the emotional benefits for the individual tourist and the educational value of such close experiences with nature, tourism in the Great Barrier Reef is an excellent source of revenue for the Australian Government. Take, for example, the Environmental Maintenance Charge (EMC) that is levied on tourists visiting the Great Barrier Reef. Racking up to a modest $3.50 for tourists spending more than three hours on the Reef (Great Barrier Reef Marine Park Authority, n.d.), it is only when the total number of tourists visiting the Reef is factored in that the financial contributions of tourism on the Great Barrier Reef becomes obvious. According to the GBRMPA, more than a million people visited the Reef in 2013 alone (GBRMPA, n.d.).

However, the sheer volume of people visiting the Great Barrier Reef cannot be without consequence.

With all that diving, snorkeling, boating and yachting come the challenges of keeping wildlife safe from dangers such as the slicing blades of outboard motors and collisions with boats and ships. Tourists more often than not also spend full days on the Reef, if not more, and this inevitably results in litter and human waste. One example is greywater, which is used water that has not come into contact with toilet waste, according to the Singapore’s Public Utilities Board (2014) definition. Another is bilgewater, defined by the Merriam-Webster online dictionary (n.d.) as water that collects in the bilge of the ship, its bottommost part. Such anthropogenic substances are of concern to the GBRMPA, which maintains several pages on “Responsible Reef Practices”, with one section specifically set aside to address the proper handling and disposal of these substances.

Greywater, bilgewater and other unwanted waste products will not only cause harm in the form of pollution when introduced into marine environments like the Great Barrier Reef, they also upset delicate biological processes.

For example, certain substances can provide nutrients that rapidly accelerate eutrophication, a process that occurs in both freshwater and marine ecosystems when unusually large amounts of nutrients (such as phosphates or nitrates) are added introduced into water bodies (United States Geological Survey, 2014). According to Smith, Joye and Howarth (2006), eutrophication can lead to “dramatic changes in the composition and structure of aquatic food webs” through the explosion of populations of algae (see graphic above). Such nutrient enrichment is also partly to blame for population increases in the crown of thorns starfish (Acanthaster planci) that is widespread along the Great Barrier Reef and devours coral voraciously (GBRMPA, n.d.). This particular threat will be discussed in greater detail in a later post.

Another human activity that is detrimental to the Great Barrier Reef is coal mining. Just this year, the Australian government approved the creation of the largest coal mine in the country: the Carmichael Project. Valued at a whopping $5 billion and expected to create more than 5,000 jobs once underway, this approval will allow the Indian mining company Adani to dig up roughly 60 million tons of coal every year from Galilee Basin, Queensland, transport it to Abott Point port and ship it to India for use in coal-fired powerplants.

This multifaceted project also has a wide range of potential effects on the reef. Dredging of up to five million tons of seabed to prepare for coal carrying ships as well as the possibility of coal carriers running aground (as in the case of the Chinese-registered Shen Neng 1) are some of the more obvious effects. However, some of the longer term effects of the Carmichael project include exacerbating the existing problem of coral bleaching, a harmful process that is accelerated by climate change, fueled in part by coal-fired powerplants. As such, the Carmichael Project does not only result in far-reaching ramifications for the Great Barrier Reef, but all marine life in general as well. It does not make it any better that the Carmichael project, though facing fierce opposition from environmental advocacy groups like Greenpeace, is expected to churn out coal for sixty whole years.

The saying goes that mistakes are the stepping stones to success. Correcting a mistake results in learning acts as a preventative measure of sorts against similar mistakes in the future.

Sadly, some mistakes only require a single occurrence to cause irreparable damage. This post covers two mistakes that have seriously affected the Great Barrier Reef and the creatures that reside on it.

The first Case Study of an accident on the Great Barrier Reef is the case of the Shen Neng 1, a Chinese-registered bulk coal carrier. The massive ship ran aground on Douglas Shoal in the Great Barrier Reef on the 3rd of April, 2010, gouging out a massive 115,000 square-metre section of the reef (and doing moderate damage to other parts of the reef) before spewing its load of coal into the clear waters (Great Barrier Reef Marine Park Authority, 2011). Nine days elapsed before the stricken vessel was finally refloated on 12th April, 2010. Though the salvage efforts were valiant, they could not reverse the effects of the ship’s grounding.

As compiled in the GBRMPA’s Shen Neng 1 Grounding Impact Assessment, the damage caused by this one mistake is beyond extensive. Along with the damage caused by the ship physically running aground, chemicals were also introduced into the reef in this totally avoidable accident.

An example of such harmful chemicals is antifoulant paint from the Shen Neng’s hull. Antifoulant paints are engineered specifically to be toxic to sea life so as to prevent the attachment of such animals to the ship’s hull (known was ‘fouling’, which explains the naming for this kind of paint). This paint was scraped clean off the ship as it slammed into Douglas Shoal (GBRMPA, 2011). In addition, more than three tons of fuel from the Shen Neng 1 leaked into the waters of the Reef, coupled with roughly 5,000 litres of oil dispersant (which does not reduce the toxicity of the fuel). Fuel oil is also slow to be degraded by native marine microbes, which means that the toxicity of the oil remained long after the actual incident.

Given the grievous physical damage to the Reef as well as the lingering toxicity from substances originating from the Shen Neng 1, this is one mistake that cannot be allowed to happen again.

The second Case Study involves a lesser known accident on the Great Barrier Reef. This time, it involved the US Marine Corps, two AV-8B Harrier jump-jets and and four bombs.

In the year 2013, as a lead-up to exercise Talisman Sabre, two Harriers on a training mission were faced with an unexpected problem: the presence of a civilian vessel in target area around Townshend Island for their training bomb drop. Unable to complete their drop and low on fuel, the pilots of the jets were forced to jettison two 500 pound GBU-12 munitions, along with two other inert dummy bombs, into the ocean. This was done as the bombs would seriously hamper the Harriers’ ability to land safely.

The GBU-12 bombs were, thankfully,  eventually recovered following their discovery by an Australian warship (the two dummies were left where they fell, since they posed no threat to the Reef and would mean risking dangerous diving conditions to retrieve). Should the GBU-12s have exploded, each 500 pound weapon, engineered to completely annihilate tanks and other armoured targets, would have had enough strength to do considerable damage to the Reef. Fortunately, unlike the Shen Neng 1, this accident did not have a chance to leave a lasting impression.