The Threats Of Human On The Great Barrier Reef

Introduction

The Great Barrier Reef is the largest, longest, and most popular complex of reefs in the world. It is located in the Pacific Ocean right off the northeastern coast of Australia and extends further than 1,250 miles with an area of about 135,000 square miles. All of the reefs are completely made up by the skeleton and skeletal waste left behind from deceased marine life. The framework is made from the calcareous remains of coral polyps and hydrocorals and are held together by coralline algae (Reef 2010). While the reef is home to thousands of breathtaking species (some of which include a variety of hard coral, fish, plants, and crustaceans) and a great place for research, it is currently at a great risk. The Great Barrier Reef is left vulnerable to numerous threats such as tourists, climate change, storms, coral bleaching, and ocean acidification. In the past decades, half of the coral population has been destroyed and global warming has caused deadly acts of coral bleaching (De’ath, Fabricius, Sweatman, & Puotinen, 2012). Many organizations and groups have been formed and have been working together for hundreds of years now in order to brainstorm new strategies and pass new legislation in efforts to save this irreplaceable ecosystem. In fact, the Great Barrier Reef has become the “most structured conservation effort” in the world and conservationists have raised over hundreds of billions of dollars in support (Johnson, Marshall, & Authority, 2007).

Inevitable Threats to the Reef

The Great Barrier Reef has been degrading over the last hundreds of years and a significant number of current events have been contributing to its downfall. Unfortunately, many of these threats are inevitable and naturally caused by the environment, so it is harder for us to control. The reef-building coral are extremely sensitive to increased sea water temperatures, ocean acidification, water pollution from runoffs, and coastal developments (Burke, Reytar, Spalding, & Perry, 2011). Climate change includes any events such as increased frequency of severe weather, rising sea temperature, ocean acidification, and rising sea levels. Severe weather such as hurricanes or tropical storms, which bring powerful rains and winds, can destroy and weaken the reef structure (De’ath et al., 2012). It is predicted that the sea level will rise an average of 15mm a year (Buddemeier & Smith 1988). Rising sea levels can have a negative effect on organisms who thrive in shallow waters, pushing them further out to sea and in deeper waters where it may be cooler in temperature and harder to find food. Rises in sea levels can also interfere with freshwater ecosystems that are located nearby, as they would be introduced to and contaminated by the ocean saltwater (Blanchon & Shaw 1995). The ocean is predicted to rise in temperature by at least 2 degrees Celsius between the years of 2050 to 2100. Corals and other essential plantation in the reef undergo heat stress when temperatures rise because they do not have the ability to adapt fast enough to these new temperatures. This causes coral to quickly die off and is known as coral bleaching (Hoegh-Guldberg, Mumby, Hooten, Steneck, Greenfield, Gomez, & Knowlton, 2007). The coral expels the algae (zooxanthellae) that is inside of their tissues, causing them to turn completely white. After they bleach, they either survive and regain their color when the temperature drops at an extremely slow rate, or they die off completely (De’ath, Lough, & Fabricius, 2009). In a recently published article by Nature in 2018, it includes information about a 2016 heatwave that killed about 30% of the coral in the Great Barrier Reef in a nine-month period (Hughes, Kerry, Baird, Connolly, Dietzel, Eakin, & McWilliam, 2018). Multiple field studies have concluded that sedimentation can degrade the coral reef at a local scale (Fabricius 2005). For example, many reefs in the Caribbean were completely destroyed by an increased amount of nutrients and sediment runoff from the land (Hughes 1994). These studies, published in 2004, indicated that high levels of dissolved inorganic nitrogen and dissolved inorganic phosphate both reduced calcification in corals by up to 50%. A decrease in coral densities were also reported (Fabricius & De’ath 2004). The increased amount of sediment and nutrients flowing in the water reduces the availability of light that the coral and sea plants use to photosynthesize, degrading the amount of food they can produce (Brodie, Kroon, Schaffelke, Wolanski, Lewis, Devlin, & Davis, 2012). Recently, it has been determined that an increased growth of microalgae also follows runoffs due to the newly increased amount of consumable nutrients. The success of many coral species is then inhibited by these microalgae which can “take over” the coral and weaken them, allowing the coral to be more susceptible to diseases or climate impacts (Moriarty, Pollard, Hunt, Moriarty, & Wassenberg, 1985). For example, in the Chesapeake Bay, eutrophication and hypoxia did not occur until the 1930s, when large plots of land were cleared for agricultural purposes, creating an increased runoff of sediment (Cooper & Brush 1993).

Threats to the Reef by Human-Related Activities

The Great Barrier Reef is also threatened by human related activities. Recreational fishing is permitted in the reef, and much of Australia’s revenue is due to commercial charters and speed boats taken by tourists (over $1 billion annually) (Craik 1981). However, overfishing continues to be a problem and threatens the marine life in the Great Barrier Reef. Overfishing can also lead to outbreaks of a variety of species that are indirectly harmful to coral. One organism that feeds on coral is the crown-of-thorns starfish Acanthaster planci. This has been another contributor to the recurrent mass mortality of coral since 1960 and these organisms occur in mass outbreaks that occur frequently (Ormond, et al., 1990). A theory has been published that blames overfishing for causing these outbreaks of starfish. Species that prey on the larval or juvenile stages of these starfish are extremely limited or gone and the population of Acanthaster planci can not be controlled (Steven 1988). A type of deadly fishing method, called blast fishing, is sometimes used in tangent with explosives in efforts to stun or kill schools of fish. Since blast fishing is limited to shallow waters, the blasts can cause serious harm to coral nearby, shattering their multiple colonies and tissues (Fox, Mous, Pet, Muljadi, & Caldwell 2005). The use of anchors and fishing nets left behind by fishing boats destroy the reef. The abandoned gear, usually nets, can latch, entrap, or detach coral and other plants, eliminating their ability to photosynthesize and inhibiting their ability to grow (Uthicke, Welch, & Benzie 2004). Ocean acidification occurs when oceans absorb additional amounts of carbon dioxide, which are formed by pollution caused by humans such as the burning of fossil fuels. In a study published by Nature in 1999, the concentration of carbon dioxide in Earth’s atmosphere is well over 380 ppm, which is 80 ppm more than the maximum values of the past 740,000 years (Petit, Jouzel, Raynaud, Barkov, Barnola, Basile, & Delmotte, 1999). This extra amount of carbon dioxide alters the chemical composition of the water, decreasing its pH level. This is deadly for many corals because their capacity to create coral skeletons, which house many forms of marine life, decrease. The phenotypes and genotypes of the coral currently in the Great Barrier Reef do not have enough time to adapt fast enough to the new environmental conditions (Hoegh-Guldberg, Mumby, Hooten, Steneck, Greenfield, Gomez, & Knowlton, 2007).

Conservation Efforts

There have been a great number of institutions established and many efforts put into place in order to save the Great Barrier Reef from destruction. The Great Barrier Reef Marine Park was established in 1975 and protects the reef from damaging activities. Laws such as prohibiting fishing are strictly enforced by this establishment. There are also specific zones within the park that are extremely protected and tourism access is prohibited. The park supports key educational facilities such as the Authority’s Reef HQ Aquarium, which has achieved a large reduction in energy use due to upgraded pumps and systems and solar power, in an effort to conserve energy (Day 2002). The Park has also established networks of “no-take areas” that have significantly improved biodiversity in the reef. Overall, more than 33% of the Great Barrier Reef Marine Park is now in these “no-take areas” (Fernandes, Day, Lewis, Slegers, Kerrigan, Breen, & Innes, 2005). Many other smaller conservation groups and foundations have also been created in tandem with the park in efforts to massively increase the amount of support from the public in saving the reef.

Conclusion

The Great Barrier Reef is evidently a beautiful landmark and ecosystem that millions of people love. Coral reefs protect our coastlines from damaging effects of ocean waves and the tide. They provide an abundance of habitats for some of the most diverse and intricate marine organisms. Coral reefs are also the source of nitrogen and other essential nutrients for marine life food chains and help the ecosystem by recycling nutrients (Nagelkerken, Van der Velde, Gorissen, Meijer, Van’t Hof, & Den Hartog, 2000). However, with the reef being threatened on a constant basis, most of the fate of the Great Barrier Reef lies in our hands and we must do everything possible in order to keep it in the best shape possible.