Ocean Life in the Condition of Climate Change

Introduction

The Great Barrier reef is one of the seven natural wonders of the world. It is considered one of the most magnificent natural sights in the world. It is located off the northeast coast of Australia, off the coast of Queensland. The Great Barrier Reef spans about 1800 miles and it can be up to 65 km wide in some parts (“About The Reef”, 2018).

Within this huge underwater ecosystem, there are over 400 kinds of coral, over 1500 species of fish, over 200 kinds of birds, and about 20 types of reptiles (“About The Reef”, 2018). Along with these animals, there is a great number of large mammals (“About The Reef”, 2018). The Great Barrier Reef is an important habitat because it is home to the endangered dugong and the large green sea turtle (“About The Reef”, 2018). It is also a breeding area for humpback whales since it is in their migration path (“About The Reef”, 2018).

 In 1981, UNESCO declared the Great Barrier Reef as a world heritage site (“About The Reef”, 2018). It was declared a world heritage site because of its natural beauty below and above the water (Centre, 2017). The GBR is one of the most complex ecosystems on the planet because of its extraordinary diversity (Centre, 2017).

The Great Barrier Reef is a major tourist attraction. Every year more than two million people travel to Australia to see the Great Barrier Reef (“About The Reef”, 2018). This means the GBR is a huge income for the people of Australia. People come to fish, research, and to just be tourists (Deloitte Access Economics, 2013). In 2012, there were almost 69,000 jobs for people in the tourism business for the GBR (Deloitte Access Economics, 2013). Tourism to the reef alone brings in about $A6 billion per year (“About The Reef”, 2018).

Even though it is one of the greatest natural wonders in the world, it is significantly threatened right now. Some of the largest threats to the Great Barrier Reef’s diversity and beauty is coral bleaching, large river runoff, ocean acidification, and stronger cyclones. Each of these threats are side effects of climate change. These will each be discussed along with their effects to the Great Barrier Reef in this paper.

Coral Bleaching

Increasing ocean temperatures is causing an increase in coral bleaching. When coral is put under a new stress, such as higher water temperatures, they release the algae that was living in it (NOAA, 2010). This causes the coral to turn white, but it does not mean the coral is dead, but it is now under more stress (NOAA, 2010). These algae are called zooxanthellae. They provide the coral with most of their energy and they are what gives the coral their color (Arc Centre of Excellence, 2016). Corals have a chance to recover from this bleaching if water temperatures go back to the normal temperature (NOAA, 2010). Coral bleaching can have severe biological implications. It can cause a decrease in coral growth, decrease in diversity, decrease hard coral cover, and a decrease in ecosystem complexity (Cantin & Lough, 2014).

In 2016, there was a global coral bleaching event and about 93% of the northern part of the GBR was bleached and later died from more heat stress (Lewis & Mallela, 2018). The 2016 ENSO was the largest recorded and that may have played a role in the GBR bleaching (Lewis & Mallela, 2018). A study done by Lewis and Mallela looked at the effects of climate on coral bleaching by using climate model CMIP5 and looking at interconnected environmental and climate factors (Lewis & Mallela, 2018). It was seen that increased ocean temperatures from the increase in greenhouse gases, had the largest impact on coral bleaching in the GBR (Lewis & Mallela, 2018). It was concluded that the risk for bleaching will increase if there continues to be an increase of greenhouse warming (Lewis & Mallela, 2018).

Ocean Acidification

As the amount of CO2 in the atmosphere increases, so does the amount of CO2 present in the ocean. This increase of CO2 in the ocean is dropping the ocean pH (IPCC, 2013). According to IPCC, since pre-industrial times, ocean pH has decreased by about 0.1 (IPCC, 2013). This small decrease may not seem like that big of a deal, but that decrease in pH is greatly affecting the calcification of marine animals. As the pH of the ocean decreases, the amount of calcium carbonate available in the ocean will decrease.

A study done by D’Olivo et al., analyzed 41 coral cores from Porites colonies from seven different reefs from the central portion of the Great Barrier Reef (D’Olivo et al., 2013). These samples were taken from inner, mid, and outer-shelf reefs. It was seen that growth rates were significantly correlated with calcification rates (D’Olivo et al., 2013). Porites were seen to maintain constant calcification by decreasing their growth outwards and increasing their density, so their core could be stronger (D’Olivo et al., 2013). This means the coral aren’t growing as much as they normally would since they don’t have as much calcification occurring.

In a study done by Meyer et al., it was seen that an increase of dissolved inorganic carbon and dissolved organic carbon caused from climate change, will decrease dark calcification of coral (Meyer et al., 2016). This will lead to a slower growth rate of corals and it will lead to a loss of hard substrate and later reef erosion (Meyer et al., 2016). So the increase of carbon in the ocean, causing ocean acidification, will have an effect on the life of corals throughout the reef.

Water Quality

Poor water quality is one of the biggest threats to the reef. There are 35 major reservoirs that feed into the waters of the GBR (gbrmpa.gov, 2017). This means there are 424,000 kilometers of land that drain into the GBR (gbrmpa.gov, 2017). Most of the water draining into the reef comes from farms and pastures. It is estimated that there has been an increase of 37,000 tons/year of nitrogen, 6.3 tons/year of phosphorus, and 17,000 kg/year of herbicides discharged into the Great Barrier Reef (Brodie & Pearson, 2016). It is predicted that in La Niña years, there will be larger rain falls which will lead to more river runoff into the ocean (Brodie & Pearson, 2016). This will continue the decline of water quality in the reef.

The increase in the flow of nutrients, sediment, and pesticides into the reef can overwhelm the corals near the coast and that can have a negative effect on the resilience of the reef (gbrmpa.gov, 2017). The poor water quality leads to reduced light availability for corals so it slows the growth of the corals, the nutrient runoff from land leads to an increase of crown of thorns outbreaks, coral disease, and it increases the coral’s sensitivity to bleaching (Brodie & Pearson, 2016). The increase in nitrogen and phosphorus can lead to a higher growth of algae and less diversity of coral (gbrmpa.gov, 2017). Some of these pollutants can stay in the ocean for years and that will end up effecting animals higher up on the food chain, not just the corals (14).

In a study done by Mallela et al., it was seen that the increase of phosphorus runoff into the ocean decreases the strength of the reefs. It has been seen that the phosphorus runoff into the ocean has doubled worldwide caused by agriculture, soil erosion, deforestation, and sewage runoff (Mallela et al., 2013). The phosphorus contamination leads to negative impacts for the coral reefs. The contamination can lead to decreased calcification, decreased reproduction, and a weaker framework development (Mallela et al., 2013). It has been seen that the coastal reefs in the Great Barrier Reef are regularly exposed to the phosphorus runoff and that has had long term impacts to the life of the reef (Mallela et al., 2013).

Cyclones

The Great Barrier Reef is not only made up of coral reefs, but also sea grass meadows. There is strong evidence that there is a decrease in seagrass meadows now present in the GBR (Brodie & Pearson, 2016). This decrease can be accounted for by an increase in strength and frequency of cyclones as well as larger river run offs (Brodie & Pearson, 2016). Research has shown that sea grass meadows have declined 38% since the 1980s (Brodie & Pearson, 2016). There is also a decrease in reproduction of the sea grass in the meadows and that declines the recovery and growth of the meadows (Brodie & Pearson, 2016).

In 2011, there were major river runoffs and a category 5 cyclone that had a large effect on the sea grass meadows in the Great Barrier Reef (Brodie & Pearson, 2016). Along with the natural affects, port dredging is also having a negative effect on the sea grass (Brodie & Pearson, 2016). Under the current and increasing climate, it is predicted that there will be more frequent and stronger cyclones (Brodie & Pearson, 2016). This not only affects the sea grass, but also the corals. The coral reefs are already under pressure from the decrease in calcification and bleaching, so the weaker corals won’t be able to withstand the stronger cyclones (Brodie & Pearson, 2016). This will lead to a continued decrease in coral reefs.

Animals

Even though the effects on coral in the GBR are of great concern, the animals in the GBR are also affected by the threats to the Great Barrier Reef. Sea turtles and dugongs are the animals that are most affected by the changes happening to the reef and its the environment.
          
The Great Barrier Reef is home to one of the largest populations of sea turtles in the world. With the increase in global temperatures, these turtles are beginning to be in danger. Sea turtles have temperature dependent sex determination (Jensen et al., 2018). This means the sex of a sea turtle is determined based on the incubation temperature of the egg during development (Jensen et al., 2018). Females are born in warmer temperatures, while males are born in cooler temperatures. This is starting to become a problem because climate change is causing global temperatures to increase. By 2100, it is estimated there will be an increase in global temperature by 2.6°C (Jensen et al., 2018). This may cause a higher mortality for sea turtle eggs as well as a higher female offspring production (Jensen et al., 2018). The study done by Jensen et al. showed this was happening at the GBR. The study shows there was a strong female sex bias throughout the GBR. In the cooler regions of the GBR, there is about 65-69% of the population are female (Jensen et al., 2018). In the warmer regions, there was over 90% of the sea turtle population that was female (Jensen et al., 2018). This is of great concern because it is highly probable for there to be complete feminization of sea turtles in the future (Jensen et al., 2018).

The Great Barrier Reef is home to dugongs. Dugongs are sea mammals that are slow breeding and live a long time (Leong, 1998). They feed on the seagrass meadows in the shallow waters of the Great Barrier Reef and they are extinct in most places of the world (Leong, 1998). Since the GBR is one of the few places in the world that the dugongs live in, the presence of the dugongs helped the GBR become a World Heritage listing (Leong, 1998). This means there is an international responsibility to save the species (Leong, 1998). As of 2011, there are only 600 left in the GBR (Brodie & Pearson, 2016). This decline is caused by the increase in fishing near the reef and the loss of sea grass habitat (Brodie & Pearson, 2016).

As talked about earlier in the paper, the sea grass meadows of the GBR are decreasing because of cyclones and river runoff. If there is no change to the water quality or the intensity or frequency of cyclones, there is a chance of the dugong’s habitat being lost. That may lead to the extinction of the dugongs. That is one of the reasons why it is so important for the river runoff to be limited.

Impacts to Humans

As stated earlier, the Great Barrier Reef is a huge economic benefit to the people of Australia. From tourism alone, the reef brings in close to $A6 billion a year to Australia. Tourism accounts for about 91% of the regions value and employment (Deloitte Access Economics, 2013). So the GBR is a very important aspect of the Australian economy. If the GBR were to completely die or not lose its World Heritage title, there will be a huge decrease in tourism and that will greatly impact the economy of the east side of Australia.

Within the past five years, there has been a steady decrease of international tourists to the region Australia with access to the GBR (Deloitte Access Economics, 2013). This lead to a decrease of about 23% in the amount of money spent by the tourists (Deloitte Access Economics, 2013). If this decline continues to happen, it will have a huge impact on the Australian economy near the GBR. It can also put thousands of people out of jobs.

Mitigation

Most of the threats to the Great Barrier Reef will require a worldwide change, such as slowing the warming of the ocean from the increase of greenhouse gases or decreasing the amount of carbon dioxide present in the atmosphere. There are a few things that can be done locally to help save the GBR. The Reef 2050 Long-Term Sustainability Plan was created by the Australian and Queensland governments. The goal of this plan is to make sure the Great Barrier Reef remains one of the natural wonders of the world and to improve the state of the reef (Australian Government, 2015). The Reef Plan 2050 takes into the consideration of cultural and ecological knowledge to create the best plan to protect the Great Barrier Reef (Australian Government, 2015). There will be a review and revision to the Reef Plan 2050 every five years, beginning in 2020 (Australian Government, 2015). This will allow more scientific research to help better the plan (Australian Government, 2015). From the outlook report 2014, there are still major challenges to the Great Barrier Reef. These include climate change, illegal fishing, and land-based runoff (Australian Government, 2015).

River runoff into the ocean is the greatest source of pollution to the ocean and the Great Barrier Reef (Australian Government, 2015). So far there has been a better quality of river run off. The pesticide load has been reduced by 28%, sediment load has decreased by 11% and total nitrogen load has decreased by 10% compared to the measurements in 2009 (Australian Government, 2015). With the continual decrease in pollutants into the reef, it will take some time before the effects are seen (Australian Government, 2015). The Reef 2050 Long-Term Sustainability Plan is aiming to reduce the nitrogen load by 80% and reducing sediment loads by 50% by 2025 (Australian Government, 2015). To do this, the Reef 2050 Long-Term Sustainability Plan sets to work with industries to practice better water quality management, requiring farmers to work under an “environmental risk management plan”, and working with local governments to improve water quality in urban areas (Australian Government, 2015). There is an additional $A100 million to use on the improvement of water quality (Australian Government, 2015).

Climate change is the biggest threat to the GBR through increased temperatures and ocean acidification (Australian Government, 2015). An international effort as well as a local effort is needed to help protect the reef (Australian Government, 2015). To do this, Australia has set a goal to reduce emissions to 5% of what they were in 2000 by 2020 (Australian Government, 2015). Australia has set a budget of $A2.55 billion for helping businesses and household with these reductions in emissions (Australian Government, 2015).

As stated earlier, Australia relies heavily on seaborne trade for their economy, but in order to save the Great Barrier Reef, it is important to make sure the ports and dredging are ecologically stable. So far there is now a permanent ban on disposal of capital dredge near and in the Great Barrier Reef (Australian Government, 2015). There used to be five projects proposing disposal of capital dredge near the GBR and now there are none (Australian Government, 2015). Also, the government will restrict new port developing near or in the GBR and if there is a new port development, it must be consistent with the Great Barrier Reef Marine Park Act, the Queensland Marine Parks Act, and their regulations and zoning plans (Australian Government, 2015). To decrease the amount of disposal of dredge, there will be a mandatory reuse of port related capital dredge spoil and an increase of on land disposal of capital dredge at Abbot point (Australian Government, 2015). There will also be a decrease in the support by the government of trans-shipping that affect the GBR.

Since one of the threats to the GBR is over fishing and illegal fishing, the Reef 2050 Plan set aside $A10 million to buyback fishing licenses (Australian Government, 2015). There will also be new net free zone across the reef (Australian Government, 2015). To make sure there is a continual diverse ecosystem, the Reef Plan 2050 has allocated $A2 billion for research and management of the reef (Australian Government, 2015). This allows there to be partnerships with private and public research and bringing the two together to allow for better success of the research (Australian Government, 2015). This plan understands the importance of research and that research is necessary to keep the reef healthy for the future (Australian Government, 2015).

There are a few nonscientific boundaries that affect the mitigation of the Great Barrier Reef. There are quite a few things that positively affect the Australian economy but will harm the GBR. One of these things is industrial development. If there continues to be an increase in port development, there will continue to be risks to the reef (Benham, 2017). But without the development of the ports, there will be a negative effect to the populations living in those areas (Benham, 2017).

The problem is deciding what is more important, the protection of the reef or the economic and social benefits from the port developments. Also, seaborne trade greatly affects the GBR, but it has a huge economic impact on Australia and other countries. Controlling seaborne trade and limiting it to certain areas is something that will require the help of many countries and it may affect Australia’s economy as well as other countries.

Overall, the Great Barrier Reef will be in danger if action is not taken soon. Australia has the greatest responsibility for caring for the reef, but it will take work from all over the world to save the reef and get its quality back to where it was.

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