Category: Great Barrier Reef

The Great Barrier Reef is located off the east coast of the Queensland mainland, Australia with a latitude of -18.193182° N and longitude of 147.45079° E. The reef covers 344,400 square kilometres earning the title of world’s largest reef, containing 900 islands stretching for over 2,300 kilometres and over 2,900 individual reefs. (figure 1) The reef is under great threat due to environmental and human induced issues. One of these issues being the crown-of-thorns starfish outbreaks which lead to the inability for coral to regenerate and grow within the reef due to consumption. There have been at least two distinctive plans of management for this issue including eradication by injection of lethal substances and the physical removal resulting in termination. A second common issue causing destruction to the reef is marine wildlife destruction due to human influence, implementation of laws and site closures have been enforced for tourists and recreational users to ensure safety for the reefs. Overfishing is another human induced issue negatively impacting marine life in a domino effect. Programs organised by governing bodies involving setting regulations of total allowable commercial catches and creating designated fishing zones depending on the reef’s current health.

Crown-of-thorns starfish can possess a productive role in healthy reef conditions by consuming faster-growing corals, allowing the slower-growing corals the opportunity to regenerate and catch up enhancing the coral diversity of the Great Barrier Reef. However, this intensive consumption of coral by the crown-of-thorns starfish may also apply more stress on the reefs. Especially if the reefs are already struggling to recover from recurrent bleaching events, largely impacting the restoration efforts of the reef’s coral. Once crown-of-thorns starfish become overpopulated, they begin to pose a threat not only economically with the added costs for employment, equipment and program funding but also to the World Heritage-listed Great Barrier Reef. The starfish spikes or spines contain a poisonous toxin which is harmful to both humans and marine wildlife, negatively impacting Australia’s tourism and fishing industries.

A program labelled ‘The Crown-of-thorns Starfish Control Program’ was established in the year 2012 delivering the ideal response to population outbreaks, in coordination to the Marine Parks Crown-of-thorns Starfish Strategic Management Framework. The program involves manually culling starfish by sending vessels occupied by professionally trained crews to inject either bile salts or household vinegar into the starfish both of which have lethal affects. (figure 3). Surveillance and monitoring activities are conducted to ensure culling targets are met in locations with the greatest benefit, progress is measured, and management outcomes are sustained once they are reached.

The current program put in place to restore coral reefs by lowering the population of crown-of-thorns starfish is an effective and manageable plan of action. Its regular harvest of starfish and follow up monitoring activities demonstrate the commitment to restore the coral reefs. However not all 2,900 reefs can be attended to at once meaning culling has to be prioritised depending on which reefs are in the most need and best accessible by vessels. This may become a problem if more reefs are in dire need than can be attended to.

Physical removal of the starfish from the reef is recommended by The Khaled bin Sultan Living Oceans Foundation. The physical removal involves experienced divers moving the starfish off the reef using wooden sticks, boat hooks, PVC pipe, metal spears or any other easily manipulated rod. The rods become necessary in the cases where the starfish hide in crevices suctioned onto the reef and need to be pried off in order to be removed. The starfish are placed in large canvas bags, rice/flour bags or mesh bags to be disposed of on land by burial or burning. If out at sea on a ship or boat the starfish may be placed into a large container with fresh water and left over 48 hours. Once enough time has passed disposal may be safely issued by leaving the starfish over the open ocean no less than 80.5 meters from shore (50 miles).

This management strategy is more dangerous than the previous mentioned injections as the bags may be pierced by the starfish spikes, poisoning the divers. It is still however manageable and effective as it reaches its end goal of minimising numbers of crown-of-thorns starfish in coral reefs.

Pollution to the reef although often done blindly it is not uncommon. Everyday chemicals such as sunscreen and lotions provided by tourists visiting the reef can wash off swimmers’ bodies and into the water. Although protective to us they have an opposite effect on marine wildlife causing harm to the reef’s residents and reef itself. Another issue with the large number of human encounters cause by tourism is damaging coral with physical contact. Most visitors will unintentionally touch, kick or trample coral when in the water, while scuba divers can also knock coral with their gear or kick up sediment all of which can break the coral or damage the coral tissues. (figure 4) Other risks include littering, changed animal behaviour from feeding or diver interactions, boat strikes to marine mammals and turtles and anchor damage to corals and seagrass meadows.

The Great Barrier Reef was placed on the World Heritage List in 1981 for all its colourful marine wildlife and unique ecosystem, attracting approximately two million tourists per year. The reef is a popular destination for recreational marine activities such as boating, swimming, snorkelling, fishing, turtle and whale watching and scuba diving all ways to enjoy the reefs beauty and biodiversity.

Strict laws and rules have been put into place for tourists and tourist companies to minimise human contact and preserve coral. Fines and even jail time may be issued to those who fail to comply with the stated laws. These rules include:

• Staying off the bottom of the ocean
• Do not feed the turtles or other marine wildlife
• Do not litter
• Never touching corals
• Do not harass or capture marine wildlife
• Take nothng from the reef except photos

Hфving rules and laws put into place may be helpful for people to recognise that the reef is not a touch pool, especially if consequences are put into effect. Regular monitoring would have to take place in order to maintain the effectiveness of the beforementioned consequences. Otherwise some visitors may not follow instructions as there is no punishment for their actions.

Temporary site closures or exclusion zones may be put into place if it is believed to help reduce stress and improve outcomes for coral. When implicating site closures tourism companies and economic factories should be taken into consideration to ensure no losses are made.

Temporarily closing the marine park and or particular zones is and effective way of preserving wildlife as it allows periods of time for the coral to be completely untouched and undisturbed/ This can also give the coral a chance to restore itself. The only issues with park closure are the partnership or tourism losses made if people are not made aware prior to the momentary shutdown.

Overfishing has already shown a dangerously low decline in Australia’s fish stocks. Two main factors account for this issue; intensive fishing efforts by commercial and recreational fisheries, along with the low biological productivity of fish hence being unable to regenerate quickly. Almost 21% of species assessed in Australian waters were deemed overfished in 2005. In the case of a herbivorous species being overfished the amount of algae around the reefs would greatly increase posing a threat to the corals, the carnivorous species would then begin to decrease shortly after as they would have less options for food sources.

Management plans for fisheries within the Great Barrier Marine Park are made the responsibility of the Queensland Government through the Department of Agriculture and Fisheries. This includes limits to the number and size of fish allowed to be kept by recreational fishers, commercial licencing, seasonal closures, and setting of total allowable commercial catch. Areas of permitted fishing is managed in the Great Barrier Reef Park Authority by the Australian Government as a part of the 2003 Great Barrier Reef Marine Park Zoning Plan.

Controlling aspects such as the areas fishing is permitted and the requirements each fish must meet to be taken allows the fish time to reproduce and build up numbers. It also gives carnivorous fish a sufficient source of nutrients. The Australian Institute of Marine Science long-term monitoring team reported that after less than two years of the suspension of fishing (in 2005-2006) the most important commercial fish species, coral trout, had increased in abundance by about 50% on mid- and outer-shelf reefs. Thus, proving the efficiency of this program.

The Great Barrier Reef faces endangerment as a result of crown-of-thorns starfish overpopulating, feeding off and destroying vital corals, high numbers of tourism year long, restricting regeneration processes of corals and behavioural habits of wildlife, and overfishing within the reef, dooming species to endangerment and killing off food sources for carnivorous fish. Multiple management strategies have been put into effect by governing authorities of the marine park. Two separate yet equally effective methods of eradication have been issued for the decrease of crown-of-thorns starfish within the reef. The second method does pose a higher risk in getting poisoned by the starfish spikes but done carefully and by trained professionals there is no harm. The approach taken to minimising the negative impact of gross tourism to the reef is more trust related meaning its enforcement could lack if proper supervision is not provided. Laws and rules have been published to protect the reefs wildlife only if followed appropriately, the second and stricter plan of action is temporarily closing off specific sites if not the whole park. Overfishing is delt with a set list of demands each species must meet to be removed from the reef, follow ups of water patrols must be included to continue the implementation of this request. Secondly fishing area zones are controlled in the event of rehabilitating the reef in the areas that need it most, giving them time to grow back and regain nutrients.

The following research was conducted in order to assess the effect(s) caused by the depletion of a specific predator, the Green Sea Turtle, in the Andros Barrier Reef on the coral reef growth of coral reefs and survival. More specifically a cascading top down effect on the coral reef ecosystem is inferred, since Green Sea Turtles both directly and indirectly control the amount of sea-grass and algae in this ecosystem. Excess nutrition could be regarded as a liability for the coral reefs, and the Green Sea Turtle is of help by clearing up the effects of excess nutrients and seagrass growth. The depletion of the Green sea Turtle directly contributes to growth and overabundance due to their role in regulation and consumption of the sea-grass and algae. It is quite important to observe how the level of nutrient production of the coral reef is detrimental to the Green Sea turtle survival. Moreover, the algae and sea-grass have a competitive relationship with the corals, contending for nutrients, sunlight, and space. The overgrowth of algae and sea-grass on the coral reef could dispatch large patches of corals, this is why it is such a source of interest in order to magnify its effects on these biological structures.

The Andros Barrier Reef is the world’s third largest barrier reef, extending approximately 220km from the Joulter Cays, found around the Andros Island, in the Bahamas (Davenport, 2008). The reef is divided into five main zones based on architectural formation, distribution and development; the lagoon, the outer-fore reef, the inner-fore reef, reef crest, and the back reef. The Andros is not considered as a “true” barrier reef system due to the shallow lagoon depth and close proximity of the shoreline. The Andros Barrier Reef slopes into a vertical cliff, which drops to a depth of approximately 2000 feet into an ocean trench, typically called “Tongue of the Ocean”. The Andros Reef consists of small sized colonies of soft-bodied coral polyps. Their hard skeletons make up the reef exoskeleton. The main species of corals found in the Andros Reef are the smooth brain coral, staghorn coral, water gorgonia, and the sea rod.

Barrier reefs are of high importance because they are the most diverse ecosystem on earth; the Andros Barrier reef is home to twenty-five percent of all marine species (Cranton and Sanders, 1993). Scientist have described over 164 species of fish and coral which make up the Andros Barrier Reef. The coral reef relies on herbivorous fish to maintain the balance in algae formation and growth, since these compete with the corals for sunlight, space, and nutrients which are of extreme importance for coral reef survival. If unregulated, their growth could kill large patches of coral. In the following research, the effects of the depletion of reef sharks from the Andros Coral Reef, as well as inference upon the affects in growth of juvenile fish living in the seagrass bed, are assessed. For the following, we propose that the depletion of the reef sharks on the Andros Barrier Reef will create a cascading top-down effect in the coral reef system.

The world’s ecosystem is run through its trophic level. Trophic, which is derived from the Greek word for food and/or feeding, essentially describes an organism’s position in the food chain. This position is determined by the tendency for the organism to eat or be eaten. Primary producers, which are autotrophic, utilize the sun’s energy for food and convert it to biomass. The biomass will in turn, be consumed by primary, secondary, and tertiary consumers. Each of these interactions would constitute as to what is known as an ecosystem’s trophic level. As you can see from the figure above, the trophic dynamics of an ecosystem will yield a pyramidal shape with the bulk of primary producers on the bottom and a lower amount of top predators at the top. It is important for this distribution of organisms in their respective trophic levels to remain intact, for a shift in balance would yield undesirable effects for the ecosystem.

The relationship between the organisms of any ecosystem can be visualized through the organization of their respective trophic levels in a food chain. A food chain contains four main trophic levels: primary producers, primary consumers, secondary consumers, and tertiary consumers. The primary producers are the foundation of any food chain and consist of autotrophs that synthesize organic compounds through photosynthesis. In a coral reef, common autotrophs are phytoplankton (i.e. diatoms), algae, and zooxanthellae. Feeding off this first level of organisms are primary consumers. These consumers are herbivores, and include a range of marine life such as zooplankton, grazers, and invertebrate larvae, sea urchins, crabs, and sea turtles (CoralScience.org). They play an important role in the function of the coral reef system by regulating algae. Too much algae can be detrimental to corals and the ultimate result is the dying off of corals. Specific to the Andros Barrier Reef, the Queen Angel, King Angel, Green Turtle, and Parrot Fish (The Andros Barrier Reef) are all abundant primary consumers that feed on soft coral, coral skeletons, plants, and plankton.

The next trophic level of organisms in the food web is secondary consumers and consists of corallivores, piscivores (fish feeders), plankton feeders, and organisms that feed on other benthic invertebrates (i.e. primary consumers) (CoralScience.org). Secondary consumers found in the Andros Barrier reef include the Blue Tang, the Flying Gurnard, the Rock Lobster, and the Queen Trigger. They are known to feed on plankton, small crustaceans and invertebrates, worms, and sea urchins, respectively. At the top of the food chain are tertiary consumers, large fish that essentially eat smaller fish that are below them in the food chain. Tertiary consumers may be predators but may also be non-predatory as well. In the Andros, the tertiary consumers include the Great Barracuda, feeding on herring and tuna, the Green Moray, feeding on fish and squid, the Trumpet fish, feeding on small fish, and the Reef Shark, feeding on anything, including small fish and cephalopods.

The balance of each trophic level in an ecosystem is very important to the survival of the ecosystem. When we are faced with the question of which organisms in an ecosystem play a key role in the regulation of its trophic levels, ecologists solemnly believe it to be the apex predator. The trophic stability of an ecosystem is highly dependent on predation. Predation from an apex predator keeps other trophic levels in check by controlling the population of multiple species to the right proportion, preventing prey species from causing impairment to an ecosystem by becoming excessively populous (Menge and Sutherland). By keeping multiple trophic levels from going beyond their capacities, competition is eased and this would also allow growth and speciation to occur (Dodson 1974). Removing an apex predator from an ecosystem will cause the entire ecosystem to collapse.

The aforementioned truth about predation is that it helps the ecosystem. In the Andros barrier reef, the stability and diversity of the marine environment is kept intact through interactions with its top predator. The reef shark is known as the apex predator in the Andros barrier reef. Its presence is crucial for the survival of the ecosystem, so much so, that removing it will foreshadow inevitable destruction of the ecosystem in a top-down manner (Robbins 2006). Reef sharks, as apex predators, feed opportunistically as well as on sick, old and weak fish in their prey population. This tendency keeps the reef’s population competitively “fit” and will allow diversity and speciation to take place in evolutionary time. Ecologists deem sharks to be a keystone species and the concept of an ecosystem deprived of their apex predator would cause the endangerment or extinction of many other marine species in a direct or indirect manner.

There have been many studies on the direct and indirect involvement of an apex species in an ecosystem. For the basis of our research, we will observe the study reported and conducted by the AAAS (American Association for the Advancement of Science). This organization performed a study on the impact of loss of an apex predator, specifically a shark, from its ecosystem. The group recorded the effects when the shark was scarce in the environment over long periods of time and interpreted the data over the course of several time periods. On several occasions where the declination of shark presence had taken place, there would be an increase in the number of prey organisms. Since a shark’s diet consists of several species of prey, the prey would obviously experience an increase in numbers in their absence. The niche of a shark could not be intact with their declining numbers and primary consumers start to grow as seen by the model below made by the AAAS.

Due to the data above, we established the notion that losing an apex from our site would cause the increase of primary and secondary consumers, often referred to as mesopredators. Notably, reduction of the reef shark population would increase the amount of green sea turtles. Although green sea turtles are important for the health of coral reefs due to their consumption of algae, their over-abundance could be harmful for coral reef diversity. From our Andros-site food web, we observed that the only species keeping the green sea turtles at bay are the reef sharks. Without a predator, the green sea turtles experience unhindered growth and reproductive rates. The increased amount of green sea turtles would place immense pressure on the primary production of sea grass beds, being their dietary staple. Carnivorous as hatchlings but shifting towards herbivory post-maturation, adult green sea turtles only graze upon sea grass beds and algae. Eventually, their potential over-population would cause depletion of the sea grass beds, placing into motion a cascade-effect ultimately dealt with by the nursery fish. Sea-grasses shelter and host many of the coral reefs’ nursery beds. It is one of the safest places for juvenile fish to grow because predators are less likely to prod around sea-grass beds as they typically opt for slightly bigger fish. With the absence of sea grass beds, nursery fish would not have a place to grow, which would cause under-population of future generations of marine life. Diversity and speciation would experience reduction, and one after another, a species would face extinction. This is an example of the top down cascading effect that removing the apex predator from the ecosystem has on the entire ecosystem. It is important to note that with the higher demand for fisheries to hunt sharks, typically for shark fin soup and culling practices, sharks are declining due to human involvement. We may soon see a situation similar to the one described above if nothing is done to alleviate the depletion of this important predator.

In conclusion, according to Robbins (2006), the removal of an environment’s apex predator would inevitably foreshadow the top-down dismantling of the trophic web due to their opportunistic feeding habits. In opposition of biased data, reef sharks do not prey selectively on exclusively sick, weak, and elderly fish; their diets are allinclusive and help to maintain equilibrium for the prevention of overpopulation and depletion of total resources. The influence of the apex predator is so imperative, that their absence permeates through the trophic web, signaling an increase of mesopredator populations. In the case of the Andros, the loss of the reef shark would cause drastic increases in the population of green sea turtles, placing an incredible amount of selective pressure on primary producers and smaller fish. Through the topdown cascade effect, the ultimate outcome displays a loss of diversity and speciation leading to extinction and the collapse of the local ecosystem. As stated above, the Andros reef’s tertiary consumers include the Great barracuda, the Green Moray, the Trumpet fish, and the Reef shark as the apex predator in an area with over 164 fish and coral species and over twenty-five percent of all marine species as described by Crandon and Sanders (1993). However, this data may prove to be insufficient, as the presence of non-apex tertiary consumers may provide a trophic web buffer for the absence of the apex predator. Necessary data includes the inter- and intra-species exhibitions of predation and food-web interaction focused on tertiary consumers as well as longitudinal observations of a reef ecosystem that has lost the apex predator, with and without strong non-apex tertiary consumers for confirmation. What would occur with the loss of an important mesopredator such as the green sea turtle? How would other dominant non-apex predators react to the absence of the apex predator? What are some viable techniques for prevention of apex-loss? In the case of total tertiary consumer loss, would relocation of a known apex-predator from a similar environment suitably substitute for the original loss?

The Great Barrier Reef is an extraordinarily diverse and complex network of organisms that each serve a purpose to form a massive ecosystem with features that are vastly different than all others. The Reef sits parallel to the cost of Queensland, Australia where it has existed in different forms for over 500,000 years. This paper will talk about how the reef formed, as well as what made the Reef what it is today, and what its biodiversity consists of, while focusing on the human effects, both positive and negative, on the Reef.

The Great Barrier Reef is one of the most vast and diverse ecosystems on earth. This officially recognized national park and world heritage site is home to thousands of different species of fish and algae which has thrived in its most current state for 6-8 thousand years. Today, in a comparative blink of an eye, we have brought this healthy and growing ecosystem to a state of decline; between the CO2 pollution, destructive, and unnecessary over-fishing, and Climate change, humans have killed off large sections of the Reef, by causing a “bleaching” of the Reef, and will likely kill off more until effective means of pollution control around the Reef can be deployed. There are many current initiatives to protect the Great Barrier Reef, including much of it being considered protected, which guards the Reef against any sort of fishing, as well as creating areas for research and tracking of endangered species that live within the Reef. Research can only go so far though, because agriculture and development will continue to kill the Great Barrier Reef, and unless we find a way to reduce pollution and climate change, my generation could be the one that sees the extinction of this incredible ecosystem unless a proper government is put in place to protect it.

At 1,600 miles long, and 133,000 square miles of total ocean coverage parallel to the coast of Australia, the Great Barrier Reef is a network of over 2,900 different interconnected coral reefs. Researchers have mapped out the Great Barrier Reef into 70 separate bioregions, which is an ecologically and geologically defined region (Australian Government, 2016). Together, these reefs make up one major ecosystem that is the largest living structure on earth. The Reef is home to a network of over 9,000 different species of marine life that each play a vital role in providing a necessary part that keeps the ecosystem going (Nova, 2016). The Great Barrier Reef is a type of coral reef formation called a barrier reef, which is characterized by parallel structures to a coastline, as well as its tendency to grow taller than the ocean surface, making it a barrier for marine travel.

The Reef is one of the world most touristic marine locations, receiving over 2 million tourists per year, and has an estimated intrinsic value of over 300 billion dollars, as well as providing over 60,000 jobs to local Australians who provide tours of the Reef’s natural geography, which is full of cliffs and valleys, as well as gentle slopes and massive plateaus, making it a go-to for both inexperienced and experienced divers. Along with the scuba diving, the Reef’s touristic appeal has made it a large area for vacation, with many hotels and other tourist-focused locations across its nearby shore, a full economy, bringing the country almost 6 billion dollars a year, has been developed around it, making the goals of protecting the Reef compete with the goals of economic stability (Deloitte Access Economics, 2013).

In 1981, the Great Barrier Reef was put on a list for world heritage sites, or areas that are to be protected and kept untouched by development, which helped with providing funding as well as interest from researchers to understand more about the reef and how we can preserve it. The goal is to allow future generations to be able to see a monument of the earths evolution before industrialization began reconstructing the planet. In 2004, it also became one of Australia’s national parks, making 33.3% of the total Reef protected against fishing, as well as making that area open for researchers to follow specific endangered species who live in the reef (Australian Government and Queensland Government, 2015). The Great Barrier Reef, even with all its protection, has already gone through a great deal of damaging events, and is declining in a way that has brought enough concern that obituaries have been famously written for it.

What is polluting the Great Barrier Reef. The industrial revolution sparked an explosion of modern technology and development, but grew quicker then we as humans could understand. Today, we are only just beginning to understand the repercussions of our uncontrollably rapid industrialization. Many of the man-made pollution effecting oceans across the world are only increased in intensity when relating them to the Great Barrier Reef (Skwirk, 2016). One of the many things effect the Great barrier is CO2. The levels of CO2 in the atmosphere today have reached historical highs, with the highest reading being 401ppm, recorded October of 2016. Carbon Dioxide in the ocean causes the pH level to drop, or get more acidic. Ocean acidification prevents the coral in the Reef to not be able to absorb calcium carbonate in the water; Calcium carbonate is what give the skeleton, that is the InnerReef, its strength, without it the structure starts to dissolve. To drop the Carbon Dioxide levels, fossil fuel consumption must decrease, and more renewable forms of energy will need to replace it, because a non-renewable form of energy is nuclear power, which is a big cause in another man-made pollutant effecting the Great Barrier Reef (Skwirk, 2016).

Nuclear reactors produce no CO2, or no other forms of air pollutants, other than depleted uranium, the only thing that they give off is heat, lots of heat. Heat is often pumped into the air, but sometimes nuclear plants will pump the CO2 into the nearby oceans, or rivers that flow into the oceans; heat can also get absorbed into the ocean from the atmosphere, and as the atmospheres temperature rise, so does the oceans temperature (Australian Government, 2016). The Great Barrier Reef Outlook report of 2009 reported rising ocean temperatures to be the most harmful long term issue facing the Great Barrier Reef. Rising temperatures, along with extreme amounts of CO2 in the ocean, is to blame for an event called “bleaching.” Coral bleaching is when the coral polyps get stressed, which means that the water conditions, such as temperature or acidity, are no longer in there range of tolerance. When a coral polyp gets stressed, it ejects an algae that symbiotically grows inside of the corals, called zooxanthellae, which has evolved to live within the coral. the zooxanthellae that lives inside the coral is the main source of food, as well as their color, so when the coral get rid of the algae inside of them, they lose their coloring, making them white in color, thus the name bleaching. This also leads to starvation and eventual death of the coral, and generally happens in to large areas all at once; Since the industrial revolution, there have been 8 major bleaching’s, the most recent one being this year.

Another serious threat the Great Barrier Reef is sediment, or runoff. Industrialization and expansion is creating large amounts of loose dirt and debris that is causing erosion of lake and river edges. This as well as rising water levels are causing an incredible amount of sediment, or solids such as sand and dirt, to get deposited into lakes and rivers, where they end up in the ocean. Sediment causes several negative impacts on the Great Barrier Reef, the first one being cloudy, or murky water (Australian Institute of Marine Science, 2016). The Reef is not only known for its beauty under water, but when above it too, which means that clouded water due to sediment influences the intrinsic value, and could damage the economy that surrounds it if it were to get out of hand. Murky water also effects the plants itself, the coral that makes up the Reef relies on photosensitive algae for food, and murky water can drastically reduce how much light can get through the water. Another problem with sediment is that it can bring bacteria or chemicals that the coral is unfamiliar with; Coral disease is a large reason why bleaching events happen so rapidly, once the corals get stressed, they become much more susceptible to disease (Australian Institute of Marine Science, 2016).

What is happening to help the Reef. There are many reasons why the Great Barrier Reef needs protection. Between the effects of climate change, CO2 in the atmosphere, and sediment, the Reef is in more danger than ever before. As the danger grows, more and more extreme measures need to be taken to ensure the longevity of this wonder of the world, for starters, it is said that CO2 in the atmosphere must be below 350ppm to stop another bleaching event from happening. There are several organizations, as well as government funded projects, designed to help return the Reef to a state of healthy growth. Some of the most well-known agencies, like UNESCO, the same agency that created the 7 wonders of the world- which the Great Barrier Reef is a part of, has completed a 35 years’ plan starting in 2015 to provide necessary data about how to properly protect the Reef (Australian Government, 2016). The most important factor of all this is the cooperation and action from the Australian government. Currently, there is no real action being taken to protect the Reef, but with both trusts and government funding, almost 300 million dollars will soon be put into the project of protecting the Great Barrier Reef and reversing the effects of pollution (Australian Government, 2016).

The Great Barrier Reef is one of the most interesting and complex ecosystems that we have ever studied, everything from its origins, to how it maintains its vast biodiversity is remarkable, and worth preserving. With industrialization, Energy production, and explanation, the Great Barrier Reef is in true danger. Today, with few areas on the planet untouched by human development, the challenge to maintain a piece of living history has never been greater, and without support from both the government, and private agencies, we may lose yet another bit of the story of earths evolution.

The blaring foghorn erupted behind me as the ship started to inch out of the dock. The morning light shimmered on the tropical waters, like stars shining in the night sky. We left the port of Cairns, Australia at midmorning when it was bustling with traffic, bound on course to the Great Barrier Reef. Boats of different sizes and shapes were docked in the harbor. Seaplanes were taking off and landing. As the catamaran floated slowly out of the dock, it increased in speed. In a short time, we were in the waters of the Coral Sea heading toward the Great Barrier Reef .Before traveling to the reef, I read books about it and saw amazing pictures highlighting the biodiversity of the area. As my family and I boarded the ship bound to the marine reserve, I wondered whether my image of the reef was accurate. The ship came to a halt and docked onto a platform in the middle of the ocean.

I had never snorkeled in an ocean in my life. Tourists around me slowly floated away from the platform and started snorkeling. The lukewarm tropical waters of the reef were welcoming, so I dived into the waters to discover whether my impression of the reef was accurate. Layers of thick yellow corals were stacked up deep underneath me, like cargo ready for shipment. The green waters made the ocean’s depth seem comparable to a bottomless pit.

As I dived into the reef, I observed the different sizes of the corals below my knees. There were small corals about the size of a thumb, juxtaposed to the giant corals easily the size of a boulder. A Great Barrier Clownfish snuggled with a sea anemone and the corals created a flamboyant display underneath my feet. The variety of colors was as dazzling as a rainbow’s family reunion.

In the distance, I saw cement-colored fields dotting the seafloor. I suddenly realized that the patches were bleached coral. The dead coral was very drab, and it was disturbing to see a lifeless area in the middle of a thriving ecosystem. It was the color of white chalk and there was an absence of living organisms in the patches. The sun’s warm glow that typically shimmered in the water was dissolved in the dead climate. Global warming and other man-made causes had started to destroy the Great Barrier Reef and threaten its existence. I swam back toward the living reef to enjoy its exciting climate.

My brother and I snorkeled peacefully until the time came to board the ship once again. The return ride was mainly placid and uneventful. We slowly watched the scenery change as we returned to the port . And, with the evening glow reflecting over the water’s boundless surface, I stepped onto actual land.

My view of the Great Barrier Reef has changed from my previous knowledge of this marine reserve. In science class, I had marveled at the pictures of the ecosystem. After this experience, my view of the reef is different and I now understand the impact of pollution and global warming on the coral reef and other natural ecosystems. In retrospect, my trip to the Great Barrier Reef was breathtaking, but I always wonder -will I ever see the same coral reef again?

Eutrophication is the situations where nutrient enrichment, increased algal growth and/or increased organic production rates have resulted in change in benthic community structure. This definition is derived from Bell et al. (2007) and international eutrophication assessments (Foden et. Al 2010).

This has been a problem since the first European settlers arrived in 1850s and started expanding their agricultural practices, increasing the discharge in water of contaminants. Nowadays, an increase in the fertility of the sediments and water column of the Great Barrier Reef shouldn’t surprise us, if we consider the great amount of deforestation and agricultural development along the coast of Queensland.

According to the Department of Biological Science and Centre for Marine Science, University of North Carolina at Wilmington, nutrient enrichment should be considered a major cause of coral decline.

In particular the elevated quantities of chlorophyll a along intensive and extensive phytoplankton blooms suggest that the Great Barrier Reef is significantly influenced by nutrients overload.

But how is eutrophication affecting the Great Barrier Reef?

The growth of benthic algae, heterotrophs (such as bacteria and viruses) and phytoplankton will be promoted by the increase of nutrients to a healthy coral reef region; this great growth might cause significant changes in the coral reef community structure (e.g. Bell 1992; Littler et al. 2009).

For example, the competition between phytoplankton and the zooxanthellae, microorganisms that live in symbiosis with corals, for light can interfere with coral growth.

Moreover, calcification rates and increase coral bleaching can happen as a consequence of stimulated growth of the zooxanthellae.

Benthic algae, also, can be threatening in many ways: they trap sediments, compete directly with corals for space, weaken the coral structure by entering the coral matrix and alone, or together with a variety of heterotrophs, promote CSDs, which were proven to be related to eutrophication.

Lastly, the conclusion that the nutrient pool of the Great Barrier Reef had reached a critical level for its survival some decades ago (Bell 1991, 1992; Bell and Gabric 1990, 1991; Bell and Elmetri 1995) is supported by the many applications of the ETM to the water quality and ecological data of this area and by the evident replacement of hermatypic corals with other benthos in these regions.

Thanks to the high ambient light intensities and water temperatures, available nutrients are easily converted to organic matter by phytoplankton, particularly in the inter-reef regions (Furnas er al. 2005).This large quantity of nutrients determines the water quality status and the impacts of benthic organisms.

Measurements of phytoplankton biomass as chlorophyll a are 2-3 times higher in inshore waters of the central and southern Great Barrier Reef (0.3-0.7 mg 1−1 ) compared to the northern areas (o.2 mg 1-1) (Brodie et al. 2007); these values are believed to reflect nutrient enrichment, associated with eutrophication caused by coastal human activities.

Moreover, the discharge of land sourced nitrogen and phosphorus flux in the Great Barrier Reef cause than increase in the extensive phytoplankton blooms (Brodie and Mitchell 2005, 2006); these changes in phytoplankton population have often been observed in different marine environments which were exposed to anthropogenic eutrophication.

The results of Bell and Elmetri (1995) also shows that there would be an increase in the production of smaller secondary producers, because of a great decrease in the diatom-flagellate ratio, and this could destabilize the food chain.

Furthermore, there is scientific evidence that the growth of dangerous corallivore such as COTS (and probably Drupella spp.) will be encouraged by changes in phytoplankton class structure.

As far as the problem of chlorophyll a is concerned, evaluations of time-series and spatial data from Kaneohe Bay (Hawaii) and Barbados were used to create the Eutrophication Threshold Model (ETM) for coral reefs. Further studies and applications of the ETM suggested that ETC-Chl a (~0.2–0.3 mg m−3) is an alarming value in regions where settlement of POM and a build-up of DOM are promoted, as well as in regions with many coral species easily affected by POMs.

The Great Barrier Reef has been severely damaged over the past 50 years by an increase in growth of coarallivores, such as COTS. This is also proved by large scale-monitoring data on the impact of COTS on the Great Barrier Reef (Sweatman et al. 2008; Osborne et al. 2011) and that circa 42% of coral loss in the Great Barrier Reef since 1985 is caused by them (De’ath et al. 2012).

It has been proved by findings that COTS larval growth is encouraged in the lower ETC-Chl a range 0.2–0.3 mg m−3, therefore showing that a chronic state of eutrophication would be defined more accurately at a range of >0.2 mg m−3 and that the proliferation of COTS in directly caused by the degree of eutrophication.

Furthermore, significant damage has occurred to the Great Barrier Reef over the past 50 years due to the proliferation of corallivores (e.g., COTS). Large-scale monitoring data show that COTS have impacted most regions of the GBR (Sweatman et al. 2008; Osborne et al. 2011); it is estimated that 42 % of all coral loss in the GBR since 1985 is due to COTS (De’ath et al. 2012). As said before, there is experimental evidence that demonstrates the critical Chl a concentration for survival and growth COTS larvae is within the lower ETC-Chl a range ~0.2–0.3 mg m−3 and thus supports the hypothesis that the outbreaks of COTS can be linked directly to the degree of eutrophication.

Figure 1, comparison of cross-shelf variation of chlorophyll a data (R&G 17, 35; F&M, 49) in Central GBR lagoon with suggested eutrophication threshold values .

Figure 2, summary of long-term GBR monitoring data (AIMS 2012); the image shows regions of chronic eutrophication by annual mean chlorophyll a values >0.2 mg m−3

As showed by long-term monitoring by the Australian Institute of Marine Science, the quantity of hermatypic corals in the Great Barrier Reef has decreased by ~51 % since 1985.

The principal causes of this are the outbreak of corallivores, like the crown-of-thorns starfish and COTS, and coral skeletal diseases; this has been proved to be a consequence of anthropogenic development, and in particular to eutrophication (GBRMPA 2010; Brodie and Waterhouse 2012 ;Kuta and Richardson 2002; Aeby et al. 2011; Haapkyla et al. 2011).

This theory was also proved by controlled laboratory and field-based studies, which showed that adding nutrients increased the rate of growth of COTS and host tissue loss loss (Bruno et al. 2003; Voss and Richardson 2006).

Moreover, as Voss and Richardson (2006) proved that small increases in N and P concentrations to values around the Nutrient Threshold Concentrations (NTCs; Bell 1992; Bell et al. 2007) increased the rate of expansion of BBD.

The quantity of hard corals in the GBR region has reduced by >70 % since development of the coastal catchments. The principal causes of their loss are attributed to the widespread growth of COTS and CSDs, and it is now widely accepted that this is attributable to eutrophication.

Much of the increased eutrophication is caused by the increased loads of nutrients discharged from coastal developments, especially phosphorus, nitrogen and chlorophyll a.

Authorities have recently taken significant action aimed at reducing runoff nutrient loads. However, further action is required to minimize the impacts of point-source discharges and particularly of P-PO4 rich discharges.

Also further investigations on the links between eutrophication and the proliferation of CSDs and coral bleaching need to be conducted.

Some reefs in regions characterized by annual mean Chl a concentrations in the lower range of the proposed ETCs namely ETC-Chl a ~0.2–0.3 mg m−3 show good resistance to physical damage but the available evidence suggests that CSDs and COTS will proliferate in such waters and therefore the eutrophication trigger values for Chl a will need to be decreased to ~0.2 mg m−3 for sustaining coral reef communities.

Moreover, nutrient enrichment will stimulate the growth of phytoplankton, benthic algae and heterotrophs; this exponential growth can change significantly the coral reef community structure. The addition of nutrients to a healthy coral reef region will stimulate the growth of phytoplankton, benthic algae and heterotrophs (e.g., bacteria, viruses); this excessive growth can cause significant changes in the coral reef community structure.

Furthermore, the increased growth of the zooxanthellae can cause a decrease in calcification rates and increase coral bleaching.

Benthic algae, also, can be threatening in many ways: they trap sediments, compete directly with corals for space, weaken the coral structure by entering the coral matrix and alone, or together with a variety of heterotrophs, promote CSDs, which were proven to be related to eutrophication.

However, according to the Department of Biological Science and Centre for Marine Science, University of North Carolina at Wilmington over-enrichment cannot be cause of a widespread coral reef degradation, because other factors can cause significant damage to corals.

Also, most of the evidence came from laboratory studies, in which corals were exposed to high levels of nutrients for short periods. A limitation of these studies is the high nutrient concentration used to get results in periods of few weeks or a month: e.g. 20 to 200 mg Nitrate. These concentrations are much greater than the highest levels measured on polluted coral reefs.

Moreover, most of the experiments were not designed with the purpose of analyzing the effects of eutrophication on corals; therefore, the results must be interpreted with care.

It is also needed further research on the validity of the pollutants that are actually being targeted, but trying to lower the quantity of chlorophyll a is certain to reduce eutrophication in the Great Barrier Reef.

Lastly, a great limitation in detecting improvements in practices and measurable results in the Great Barrier Reef health is detecting the effect of time lags and the signal of change in the system.

Good Morning members of the Raise Your Voice youth forum. Just like you, I fear for the future. A future in which if we do not solve our climate crisis and stop being so arrogant to pretend that climate change isn’t a problem, much of our beloved earth will be changed forever. I, just like many of you, have had the privilege to visit our wonderful reef, a privilege that will not be granted to the newer generations if nothing is done to save the reef. Saving the reef is a priority and should not and will not be brushed aside as a small issue. Reducing direct human impacts such as dredging, is crucial in saving our reef, as well as doing all we can to reduce the effects climate change is having on The Great Barrier Reef as well as all coral reefs around the world.

Addressing how the reef is affected through the impact of climate change and direct human activity, is the first step in saving our beloved reef. Coral bleaching and dredging are both solvable problems that are causing major damage to the reef. As of 2019, The Great Barrier Reef has lost over 50% of coral of in the last 30 years due to coral bleaching. Coral bleaching occurs when unnaturally hot, acidic waters, triggered by climate change, starves a reef’s coral by killing algae, coral’s primary food source. Dredging near reefs also have major impacts the coral. Dredging is the act of removing silt and other sediments from the ocean floor and occurs near The Great Barrier reef so that large bulk carriers can access ports. This has devastating effects on coral reefs as the sediments generated through dredging destroy coral tissue, resulting in the death of numerous coral fragments. But what does this matter? Shouldn’t we be focusing on much more important issues than the saving a coral reef?

Reefs provides essential protection to over 25% of all marine organisms and is the source of essential nutrients, such as nitrogen, for marine food chains. Losing such an important part of the environment could have potentially terrifying consequences. Over 80% of the oxygen we breath comes from our oceans, however, healthy oceans are dependant on having healthy reefs. In order for us to keep breathing, we need coral reefs. And what is worst, if we do nothing, coral reefs can be expected to gone by 2050.

Just talking about the problems with coral reefs, however, is not going save The Great Barrier Reef as well as all the other reefs around the world. We need solutions. What can be done to stop dredging and how can we reduce the effects of climate change? At first it might seem impossible. How can a single person do anything to prevent these seemingly unsolvable issues? Well as it turns out we do not need to do much. The first step in tackling our climate crisis should be to make small changes in our everyday life. Small changes such as unplugging chargers when you are not using them and taking the train to school instead of driving, all can limit your carbon footprint. By reducing the amount of carbon dioxide we release into the atmosphere, we could, as a population, limit the effects of climate change.

In terms of saving the reef directly, all we need to do is show our support. This can be done through visiting the reef one holiday or even just simply raising awareness through have conversations about the impacts we are having on the reef.

Sadly, not all people will agree on the urgency of saving coral reefs. Even after being explicitly told why we need the reef and how we can save it, some people will still disagree. For those few people I say: We need to save The Great Barrier Reef, not just because it is an essential part of ocean and not just because it provides shelter and nutrients for much of marine life, but because we owe it to the new generations. We owe them the opportunity to experience this magical reef for themselves and for it not to just become a fairy tale because we were to lazy to do anything.

Ultimately, I urge you to take action and save our beautiful reef. Even if it is just having a conversation, if we all do our part in raising awareness, we will be able to do take our children to the Great Barrier Reef and show it to them in all its beauty. Overall, we need to show our support to the reef through reducing our carbon footprint and educating people on the effects human activity is having on The Great Barrier Reef. I hope that one day I can see the reef again, I hope that in 100 years’ time, coral reefs all around the world be full of life and colour, just as they have been for us.