The Great Barrier Reef is the largest reef system in the world, stretching around 2300 kilometres. It is located on the North East Australian coastline and due to its area faces both positive and negative interactions with the atmosphere. The reef lies in an area classified as Australia’s Cyclone Zone, and for many thousands of years the reef has been struck by severe tropical cyclones, that have resulted in the changing nature of the ecosystem. The degree of impact on the reef is subject to the intensity and extent of the storm, though the overall outcome of a storm is damage for the living and non-living organisms like the coral. The damage occurs due to the large storm waves that are produced from strong winds and low-pressure systems. The forceful waves rip apart the more fragile coral and create chips and imperfections in the harder coral. In severe cyclone cases the cyclone can cause a whole reef ecosystem to be buried under sediment. Tropical cyclones also bring with them heavily-induced rain cycles. The extra volume of fresh water means that the salinity of the reef ecosystem is then distorted, and could affect the growth of the coral, as coral reefs are highly specialised and need certain conditions to thrive. The turbidity of the water can also intensify and result in coral bleaching. The atmosphere can also be a constructive interaction with the Greater Barrier Reef. For example in 2006 Cyclone Larry hit the shores of North Queensland and destroyed many homes and businesses of the surrounding area. The cyclone also struck the reef, but instead of causing destructing within the ecosystem, the cyclone prevented mass coral bleaching to occur by lowering the temperature of the water.
Lithosphere
The Great Barrier Reef is aided in its functioning and transforming by the lithosphere. The reef itself produces limestone, the exoskeleton of the deceased coral polyp. This limestone is then weathered down and reallocated by the 4 biophysical environments to other parts of the reef. The limestone is then able to create new landforms like coral cay. The limestone is also used as a defence mechanism by coral against the violent and erosive waves. Like all living organisms coral die and the death of one coral could mean the birth of new coral, as new coral will use the limestone structures created by the deceased coral to grow on. Another lithospheric factor affecting coral functioning is sediment. Sediment like sand can have the effect of clouding up the water of the reef resulting in increased turbidity levels of the water. There is then less sunlight penetration into the reef, affecting the process of photosynthesis and coral bleaching is more likely to occur. Sediment can also overwhelm the coral reefs through sediment runoff. The sediment runoff could bring with it many natural and threatening chemicals that could harm the functioning of the Great Barrier Reef.
Hydrosphere
The Great Barrier Reef tends to have best coral growth when hydrosphere conditions are at their greatest. For example coral reefs tend to have optimal growth when wave energy is high. The wave energy is broken by reef through the seaward, and produces an area of peaceful, protected water behind the reef. The waters of the Great Barrier Reef tend to flow in a northerly direction most of the year, though during monsoonal, wet seasons the formation of the waters changes, and there is a reversal in the direction of the waters. This reversal allows for the cooler southern ocean current to flow into the reef. The reversal in water direction is a key component for the ecology of the reef. The waters that run from the north are warm and highly in salinity, they provide the reef with high nutrient levels and are major influences for the diversity of the ecosystem.
Biosphere
The biosphere element of the Great Barrier Reef is how the reef grows and obtains its wonderful features. One animal that has been credited for helping to develop the reef is the polyp. Polyps are simple organisms that have a stomach and their calcium carbonate exoskeleton. Within the polyp is an interdependent alga called zooxanthallae. The two organisms provide mutual benefits with the zooxanthallae providing sugars and oxygen through the process of photosynthesis and the polyp in turn supplying nutrients. Polyp regrowth occurs with the use of the deceased polyp’s exoskeleton. Although coral reproduction is different, where the coral will release their eggs into the warm, summer water, and instantaneously corals release mass amounts of sperm. The fertilised eggs develop into larvae and the larvae continue the reef-building procedure on the dead corals skeleton. The diverse range of species within the Great Barrier Reef also has an impact on its functioning. For example crustaceans are great at executing the nutrient recycling role, while the crown of thorn star fish is known for attaching itself to coral and eating it to death.
Coastal Dunes
Atmosphere
The four spheres play a decisive role when it comes to the structure, extent and the complexion of coastal dunes. The most pivotal biophysical interaction is the atmosphere. The atmosphere’s main components impacting coastal dunes are wind, temperature and precipitation, as well as climate. Wind is a major contributor to shaping dunes through aeolion transport, where sand grains are picked up and transported to another location. The amount of sand removed from a dune is dependent on the size of the sand particles, velocity of the wind, nature of vegetation cover and more. For sand particles to be displaced they must be of a certain diameter, around 0.15mm. The faster the velocity of the wind the more likely sand grains will be moved, as there is more force behind the wind. The type of local vegetation and amount of vegetation on the sand dunes also impacts aeolian transport, as the vegetation becomes a barrier against the wind for the sand, and the greater the vegetation the less sand taken. Through the vegetation the dunes are able to continue to grow and increase their diversity. Temperature plays the role of influencing the rate of sand dryness, and type of vegetation on the dunes. Temperature values also determine the functioning of ocean currents. As temperature increases the dryness of sand increases resulting in only few vegetation that are able to live on the dunes, which then affects the rate of aeolian transport. Precipitation is also an atmospheric component that impacts coastal dunes, through the level of rainfall. The amount of vegetation on dunes is dependent on the level of rainfall, with regular rainfall meaning a greater variety and denser vegetation, and little to no rainfall putting the ecosystem at risk, through the little vegetation to protect the sand from aeolian transport.
Hydrosphere
Hydrological processes are one of the most significant components on earth for change to occur. The hydrological processes that have an impact on coastal dune ecosystems include wind-induced waves, longshore drift and rainfall. Wind-induced waves are important for developing coastal dunes, and combine both the hydrosphere and lithosphere. When there are periods of calmness within the ocean, this means sand is able to be transported from offshore deposits to the beaches. This gives supply to dunes where the winds transport the sand. On the other hand when there are treacherous conditions in the oceans the waves become powerful and crash into the coastline with such force that there able to remove sand from beaches and foredunes. Another hydrological process impacting coastal dunes ecosystems is longshore drift. Longshore drift is the transportation of sediment by currents that are running at parallel to the shoreline. Through longshore drift sediment is able to be produced in one location of a coastal system and then transferred to another location. Longshore drift allows dunes to be created by sediment that has been transported over a long distance. Longshore drift is quite common on the East side of Australia, with many of the islands up in Queensland having been made from sediment that came from New South Wales. The final hydrological process to impact coastal dunes is rainfall. The amount of rainfall has a bearing on the erosion of the sand. When there is high rainfall runoff starts to occur which in turn erodes at the surface of the sand, the surface is then vulnerable to the effects of atmospheric winds.
Biosphere
The biosphere influences coastal dunes through flora and fauna. There are three species to flora, primary species, secondary species and tertiary species. The primary species are those that are closest to the sea. These areas are only colonised by specialised plants that are able to handle salt spray, sand blast and strong winds. The main role of the pioneer species like Marram Grass is to stabilise any incoming sand. These species of fauna spread at a rapid pace, with strong root systems, and so their able to protect much of a sand dune from its various vulnerabilities. The pioneering plants as their referred to, are vital in reducing wind erosion and stabilising the sand, leading to a better functioning coastal dune ecosystem. The secondary species is the foredune vegetation. They are usually comprised of shrubs and small trees like the coastal wattle, and help in maintaining foredune sand mass. The tertiary species are those that go beyond the coastal moorland, like tall trees. The vegetation in this zone is protected from the atmospheric and hydrological processes affecting the ecosystem. The vegetation in this area is not fixed, with variables being the local topography and climate. The development of humus and growth of plants occur, the sunlight exposure and soil conditions start to change. When the soil becomes richer, it attracts shrub and woodland plants, thus changing the vegetation. This process is known as succession. Fauna on coastal dunes is not very evident. Not many fauna live on the dunes closest to the beach, as the conditions are too extreme for them to handle, with maybe only few crabs calling this area home. Along with crabs the only likely animal seen on dunes closest to beaches are striped skink. Towards the back of the dune systems an increasing number of bird species can be found.
Lithosphere
Question 2. Analyse the impacts due to both human-induced modifications and natural stress on both ecosystems at risk. How does each ecosystem adjust in response to natural stress?
Coral Reefs
Human Modifications
Human dependence on the Great Barrier Reef has been for many thousands of years, dating back to the times of the Aboriginal and Torres Strait Islanders. As human populations grow the demand for coral reef resources will increase as well. The main human induced modifications are over-fishing and tourism.
Over-fishing of the coral reef often occurs when there is an increase in the human population, as there is a now a greater demand for seafood and unique marine life. Fishermen usually target those fish that are closely connected with the coral, like the large wrasses and snappers. When the captures for these species decrease, the fishermen then target all species of fish using more efficient methods of capturing, like spears or mesh nets. As they fish down the food chain fishermen bring great vulnerability to the coral reef ecosystem. Through observation and research it’s proven that coral with no fish are more prone to overgrowth by macro-algae and increases in coral diseases. There is also physical damage sustained by the coral, through the anchors, nets and traps, which ends up causing more complications for the coral reef.
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Tourism is the other major human induced factor impacting coral reefs, and especially the Great Barrier Reef. Tourism is a key contributor to the Australian economy, with one of its foremost assets, the Great Barrier Reef bringing in $4 billion a year. Research performed by James Cook University of Cairns found several comprehensive impacts of tourism on the reef. The first being coastal tourism development, where many people visiting the reef want to stay as close to the reef as possible. The coastal developments and building of groynes and marinas near and around the Great Barrier Reef disrupts currents and frequently gravitates to the displacement of sediment. There is also increase tourism on the islands near the reef causing problems linked with sewage and rubbish. Marine based tourism also occurs in the Great Barrier Reef with the anchors and anchor chains of boats having catastrophic effects on the coral, like physical damage. Although operators are very careful when it comes to tourist interaction with coral animals, some tourists negatively interact with the wildlife causing complications in the breeding cycles and natural interactions.
Another human impact towards the Great Barrier Reef is land clearing. Approximately 25% of all land in Queensland drains out into the reef. The runoff is a major contributor to degradation in the reef, with agriculture; urban development and aqua culture all impacting the quality of the reef water. The rate of sediment runoff is dramatically increasing through greater urban populations moving to the reef and intensified agriculture. The increase sediment means in a reduction in light energy for photosynthesis to occur, resulting in greater disease and overtime the suppression of the reef. The increase in wetland clearing has also obstructed in the reef development. The wetlands provide many species of the reef habitats and nurseries. When the wetlands for example estuaries are destroyed these species will then need to find new environments and new nurseries disrupting equilibrium within he ecosystem. The wetlands also house a significant amount of water when heavy rainfall occurs. With depleting wetlands this means more fresh water will flow into the reef having damaging effects on the salinity levels of the reef water.
Natural Stresses
Great Barrier Reef natural stresses!!!!!!!
Coastal Dunes
Human Modifications
Humans have also have dramatic impacts on coastal dune ecosystems. The main reasons to human induced modifications are the ever growing desires of humans to live on the coasts, and the increase in human population. Coastal dunes are used by humans for mining, waste-water disposal, housing and many more. The activities create problems including sand inundation and species loss.
Coastal development is occurring all over the world, due to the demand of humans to live near water. Most coastal development involves the process of flattening the parallel dunes to build, and sometimes even the foredune. These actions result in the flow of sand inland being disrupted, and the protective barrier situated between the land and the sea vanishes. Another form of coastal development affecting coastal dunes is reclamation. Reclamation involves building a wall that is some distance off the coast and filling in behind the wall. It is done to extend the land out into water, and although it is positive for humans it is extremely harmful to dune ecosystems, as it alters the movement of sediment along the coast. The areas that are reclaimed are usually tidal floats that often provide sand for dune development and growth.
Humans also destroy the coastal dunes through the recreational practices that take place. When people try to make their way to beaches they usually along the plants. This creates holes in the dunes and invites resilient weeds who can cope with trampling to grow. Most vegetation degradation occurs in the foredune, which happens to be the most important part of the dune system, as it protects the least stable component of the dune system. The weight of vehicles and other means of transport compact the sand, resulting in the sand having less oxygen and therefore less plant growth. For example in Lake Huron, Ontario, Canada research has found that the increase number of vehicles having access to the dunes and beaches has caused the deeper sand to become compact, and surface sand to loosen. The loosened sand becomes vulnerable to wind erosion, and causes a decrease in the rate of organic decay and consequently the rate of soil formation is reduced. The research also found that where vehicles had treded on the vegetation, there was greater wind velocity, as there was less vegetation to be a force slowing the wind.
Coastal dunes are very specialised and tenuous. When there is an introduction in a flora and/or fauna species, this creates havoc in the dune ecosystem, as the ecosystem has certain needs to properly function. Some species were once introduced to stabilise the dunes but end up becoming the vulnerability of the dune system. One species that has caused major dune damage is the rabbit. The rabbits were introduced to Australia by the First Fleet and have been destructive ever since their introduction. Rabbits impact coastal dunes through eating the grasses and other vegetation, reducing the ground cover and they expose sand to wind erosion. An example of floral impact on the coastal dunes is the detrimental bitou bush. The bitou bush a native of Southern Africa was first introduced in the 1920’s. Once the bitou bush has entered the dune system it quickly takes over and kills all the native plants. The bitou bush is so successful due to its high-volume of seed production, large root systems and having no predators in Australia. The major problem with the bitou bush is the monoculture it creates on the dune system, with there being no diversity on the ecosystem. If the bitou bush is removed then the sand is left exposed to wind erosion, causing greater problems. Although, the problems created by leaving the bitou bush are far greater than those eliminating the bitou bush, so much of the bitou bush on the coast is being killed.
Natural Stresses
Coastal environments are constantly changing, especially coastal dunes. These changes are brought on by humans actions and natural stresses placed on the dunes. The major natural factor impacting coastal dunes is storm damage. Storm-induced waves are able to cause a great deal of damage to the structure of the dune system. The ferocious power of the storm can leave the beaches degraded with little sediment, for dune reconstruction to occur, and sometimes even erode the foredune. Structural damage comes in two main forms, one being washovers, and the other being washouts. An example of a major storm damage that has happened was in 1999 where there destruction on the coastline of Byron Bay, New South Wales. The storms were ruthless and the waves were as high as 3-metres. The storms created mass coastal erosion, with washovers taking place in several locations, generating widespread erosion in the adjacent parallel dune system. There was also recently a series of storms that occurred in Byron Bay in 2009. The strong storms meant the New South Wales Government had to fork out around$740,000 for rebuilding and repairs. The seawalls needed repairs while many houses in the area needed rebuilding and money was needed to regenerate the dunes at Belongil Beach. A further example of storms impacting coastal dunes was in Stockton Beach, Newcastle in 2007. The storms occurred over the June long weekend and resulted in approximately 100,000 cubic metres worth of sand being lost, as well as structural damage like erosion around sea walls. This caused major disturbance to the coastal dune functioning, as will take a long time to recover.
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Dune systems don’t have perfectly shaped surfaces. The dunes often have recessions and elevations along the tops of the dunes. When a storm-waves height surpasses the height of a recession in the dune, water seeps into the dune creating a washover. With consecutive, formidable storm-induced waves the washover impression deepens and widens. This results in a greater volume of water being able to spill over and flow inland. In some intense storm events like tropical cyclones, the washover may continue into the inland dunes. Luckily coastal dunes redevelop over time through constructive waves transporting sand to the beach. Although, areas hit by intense, frequent storms go through the rebuilding process much slower, due to a considerable quantity of sand being removed. Recurring, powerful storms also cause damage to the flora of the dune, further decelerating the process of regeneration. An example of how washovers have caused damage to dunes was the major storm damage that occurred at the Newcastle Port in 1974. The storm was called the ‘Sygna Storm’ due to its ability to shipwreck the MV Sygna heading for Europe. The strom has wind gusts up to 165 kilometres/per hour, and swells were up to and over 17 metres high. The impact of the storm on the dunes was the well-built foredunes had been completely flattened.
Washouts are linked with the penetration of sand barriers like those that segregate coastal lagoon from the open sea, after there has been a period of substantial rainfall. Washouts can also occur in dune systems, when there is a build-up of water in the swales that separate dunes. When there are slumps in the dunes surfaces, the water gets directed through the low points and overspills onto the beach, sometimes transport sand with it.
ADJUSTMENT IN RESPONSE TO CHANGE
Question 3. Compare and contrast the vulnerability and resilience of the two ecosystems at risk.
Question 4. Evaluate the traditional and contemporary approaches to management and protection of both ecosystems.
The two ecosystems at risk, coral reefs and sand dunes, are both highly specialised, and for this reason there have been many traditional and contemporary management strategies used to sustain them, and keep them as risk free as possible.
Coral Reefs
Traditional Management Strategies
Traditional management approaches were mostly used by the Aboriginal and Torres Strait Islanders. The Aboriginals focused on preserving the reefs and maintaining equilibrium in the ecosystem. The first traditional management plan was season hunting. Season hunting involves hunting only occurring at specific designated times of the year, for example summer. This strategy guarantees that there will be flora and fauna available for the future generations, as well as not severely impacting the process in the food web. The Aboriginals and Islanders only took what resources they needed from the reef, which helped in maintaining dynamic equilibrium in the reef. The strategy has close links to ecological sustainability, as it focuses on protection and fostering the ecosystem.
Another impressive traditional management tactic used by the Aboriginals in maintaining the reefs was restrictions on fish sizes. This practice involves only catching fish of a certain length of above. Through this practice the fish of the Great Barrier Reef are given the chance to reproduce at least once before their caught. This lets the ecosystem maintain levels of fauna and as much equilibrium as possible. Add more.
Third Traditional Management Strategy
Contemporary Management Strategies
Coral reefs are also maintained through contemporary management strategies, with one being zoning. Zoning involves establishing what can be done and where it can be done. The purpose of zoning is to diminish stress placed on certain areas of the reef and maintain their ecological sustainability. An example of zoning is allowing commercial fishing to occur in some parts of the reef, while tourism developments can occur in the outer reef area. If imposed properly zoning is a very successful tool in managing and protecting the reefs, as well as allowing present generation’s to access its natural resources without compromising the reef for future generations.
Another way in which reefs can be preserved is through benchmark data. Benchmark data is comparing the ecosystem that is at risk with the ‘standard’ of that ecosystem. Benchmark data helps in understanding whether the reef ecosystem is at the standard that it should be to be regarded as healthy. For example the standard level globally for the amount of dissolved nitrogen in the water of coral reefs is 0.014ppm. This knowledge would help in knowing if there is too much nitrogen or not enough nitrogen in the water, and humans may then be able to influence its level of nitrogen. Benchmark data is important in interpreting the risk factor the reef ecosystem has.
The managing of tourism on the reef is also a significant factor of contemporary management strategies. Tourism generally has a negative impact on the reef, so it’s important that these tourists learn more about the reefs and the need to manage them. The Great Barrier Reef Marine Park Authority (GBRMPA) makes all tourists pay a certain fee when visiting the reefs, so they can reinvest the money into education about the reefs and to manage them. One of the major issues regarding tourism in reefs is the concentration on certain areas. For example, around 85% of all Great Barrier Reef tourism occurs in the areas of Cairns and Whitsunday Islands. Though they only make up 7% of the entire Great Barrier Reef putting immense risk on these areas. Tourism in the Great Barrier Reef is usually a day trip and mostly spent on reef pontoons. Over the years there have been many pontoon accidents and so the GBRMPA decided to ban all pontoon activity unless granted otherwise. The GBRMPA has also imposed speed limits in the reef as a way of managing the risks of the reefs. As there are thousands of boats passing through the reef every day, the GBRMPA made speed limits for boats so that the risk faced by the reefs be minimised. Tourism also impacts the wildlife and breeding cycles. Fauna have certain places and times when they are breeding and sometimes humans disturb their cycles, creating disequilibrium in that area. For example research found that many bird species that regularly bred on Michaelmas Cays had stopped breeding due to the growing tourist activity on the island. The Queensland Parks and Wildlife Service (QPWS) are in charge of most islands on which birds breed, and so if there irregularities in bird breeding on an island due to human activity, then the QPWS permanently close the island from humans.
Coastal Dunes
Traditional Management Strategies
Very little is known on the traditional Aboriginal ways of the management of coastal dunes. There is archaeological proof that the Aborigines did frequent the dunes but would have only been used as camp sites or for special ceremonial occasions. The findings of middens, which are mounds of shells that indicate a seafood-based meal had occurred, are indicators to the type of marine environment in the area, and the time that the Aborigines used the resources. ASK MISS ABOUT MANAGEMENT THROUGH MIDDENS. Another traditional management strategy though to be used by the Aborigines was the use of totems. Totems are animals assumed as an emblem to an individual or family. For many Aborigines the totems were an animal ancestor of theirs. Their role was to look after and try to preserve their totem. They were not allowed to eat their totem animals or harm it in anyway. This management strategy helped in making sure species were not overhunted. The most known form of Aboriginal management of coastal dunes was back-burning or cool burning. Back-burning occurred through fires or fire stick farming, and would occur during cool periods so the fires would not get out of hand and kill the whole ecosystem. ASK MISS ABOUT MANAGEMENT THROUGH FIRES.
Contemporary Management Strategies
For successful dune protection to occur, the natural functioning of the dune must be sustained, while allowing humans to use the coastal dune ecosystem in a sustainable manner.
As dune restoration is extremely costly many bodies of power have used strategies that protect the current dunes, and keep them in the best possible condition. One strategy imposed is land-use controls. Through state and local governments there is the ability to have stricter planning laws on human activities, as undertakings on the coastal ecosystem like residential development has extremely negative consequences on the dunes. Local governments have the power to accept or decline any development applications on the dunes. With this power given to local governments the dune system, and specifically the foredune would be able to function in a more natural state.
Fencing is another management strategy against human activities, especially trampling from beach users. Dune fences are usually built around the foredune area, and assist in stopping people from trampling the dune vegetation. Particularly when the vegetation is immature and fragile, as it’s at its most vulnerable state. The fences are made of timber and wire, allowing wind and sand sediment easy access in and out. Along with fencing, fenced access ways are used for people to get to and from the beach. Fenced access ways are built through the dune, and at an angle to the prevailing wind as it minimises funnelling. They are fenced off to further protect the vegetation. With the fenced access ways many dunes have board and chain paths. The chain and board paths help the coastal dunes through reducing trampling by humans, as well as the timber slats being an obstacle to wind erosion to the exposed sand.
http://www.mrstevennewman.com/geo/Stockton/nature_change/Washover.JPG
Rise in mean annual sea temperature
Water temperature is one of the most important variables determining ecosystem function in the marine environment. External temperature controls metabolic rates, which, during non-stress conditions, increase with increasing temperatures in all but warm-blooded organisms. Consequently, persistent warmer temperatures can accelerate life history and population parameters such as growth and reproductive age, and ecosystem properties such as rates of calcification and community metabolism, until they reach a level where temperature stress accumulates and rates start to decline75.
While warmer sea temperatures increase growth rates in some organisms such as fleshy macroalgae, they may slow down growth in others because of the relative lower nutrient concentrations in warmer compared to cooler water. At higher temperatures, water column productivity accelerates, depleting the standing stock of dissolved and particulate nutrients including phyto- and zooplankton (McKinnon et al. chapter 6). For example, kelp and other temperate brown macroalgae grow most prolifically at cooler temperatures where nutrient concentrations are higher than in warmer nutrient-depleted waters18, while the productivity of other macroalgae might increase at higher temperatures (DiazPulido et al. chapter 7). Similar responses are likely to occur in other species groups, exemplifying that shifts in the relative abundances of species are to be expected, with profound but yet poorly understood consequences for ecosystem properties and species interactions. Altered reproductive timing has been linked to rising mean annual sea temperature. Of particular concern is a potential desynchronisation of the mass-spawning event of corals that occurs annually in the GBR. Thousands of coral species from unrelated taxa synchronise their annual spawning based on sea temperature and moon phase5. The role temperature plays is demonstrated at Magnetic Island off Townsville, where waters are approximately 1°C warmer than in the surrounding region and a proportion of species spawn one month earlier on this reef than conspecifics in cooler waters near-by. Similarly, reproduction of fishes on the GBR appears to be triggered by increasing sea temperature in at least some tropical reef fishes16,17,98,49, including coral trout102. Increased temperature could cause an earlier start to the breeding season in these species, and possibly a longer breeding season if thermal limits for reproduction are not exceeded.
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